The overall performance for H2/CO2 and H2/CH4 separation transcendsthe Robeson upper bounds and ranks among the most powerful H2-selective membranes. The versatility of this strategy is demonstratedby synthesizing different types of LA-α-CD-in-COF membranes.Covalent organic framework (COF) membranes have emergedas a promisingcandidate for energy-efficient separations, but the angstrom-precisioncontrol of the channel size in the subnanometer region remains a challengethat has so far restricted their potential for gas separation. Herein,we report an ultramicropore-in-nanopore concept of engineering matreshka-likepore-channels inside a COF membrane. In this concept, α-cyclodextrin(α-CD) is in situ encapsulated during the interfacial polymerizationwhich presumably results in a linear assembly (LA) of α-CDsin the 1D nanochannels of COF. The LA-α-CD-in-TpPa-1 membraneshows a high H Approaches including staggered stacking,39 oriented growth,40 and hybridizationwith other microporous nanomaterials42 have beenexplored to reduce the effective pore size of COF membranes towardthe ultramicroporous range, mainly aiming at improving the molecularsieving mechanism. Even so, to realize a tuning of the channel sizewith Angstrom-precision still remains a great challenge, and therefore,the COF membrane performance for gas separation is often limited.Covalent organic frameworks(COFs) are an emerging class of porous crystalline polymers connectedby organic building units through covalent bonds into highly orderedand periodic network structures.44 Such nanocomposite materials often possess synergistic functionalities,providing significantly enhanced properties in comparison to thoseof their individual counterparts.48 COFs having a 1D pore channelor a 3D “cage-like” pore system are ideal host matrixesfor accommodating nanoentities such as metal nanoparticles, quantumdots, organic and metal–organic molecules, biomacromolecules,metal–organic polyhedra, porous organic cages, and metal–organicframeworks (MOFs).52 The encapsulation of these nanoentities in COFs has led to the developmentof functional materials for adsorption and separation, sensing, heterogeneouscatalysis, energy harvesting, and molecular release systems.55 One representative group is the β-CD (β-cyclodextrin)-decoratedCOF nanochannels which enable an enantioselective transport of aminoacids.56 Another example is the COF nanocompositemembrane which contains a unit cell-sized MOF, exhibiting a more precisemolecular sieving for selective H2 separation.57 Thus, the construction of hybrid COFs as host–guestcomplex offers a rich playground to design gas separation membranematerials.Host–guest inclusion complexes are an interesting configurationin which a small “guest” molecule is included withinthe interior of a porous macromolecular “host” compound.2-preferential transport pathways, which are expected to exhibit anexcellent H2 permeance and high selectivity in mixed-gaspermeation. The pore-in-pore strategy provides another way to tunethe pore environment of COFs for advanced molecular-separation membranes.Inspired by the host–guest hybrid nanocomposites,in thisstudy, we present a pore-in-pore engineering concept of packing linearcyclodextrin (CD) polymers into the 1D nanochannels of 2D COF to fabricatehierarchical-structured COF membranes. These membranes have matreshka-likeultramicropore-in-nanopore channels consisting of fast and Hp-phenylenediamine(Pa-1) (TpPa-1) membrane. The α-CD is a cylinder-shaped macromolecule,composed of six glucose units, which not only has a tiny cavity diameter(0.47–0.53 nm) but also a desirable molecular dimension ofabout 1.37 nm  smaller thanthe 1D nanopore channels of the TpPa-1 (∼1.8 nm).59 Moreover, the α-CD molecules could be assembled into linearpolymers through a preprogrammed cross-linking reaction (linear assembly(LA)).61 The packing of linear α-CD polymersinto the TpPa-1 nanochannel would create numerous selective transportpathways for the targeted gas components in the resulting membrane.This strategy is demonstrated via the preparation of the LA-α-CD-in-TpPa-1membrane  alkaline solution to allowthe reaction between the encapsulated α-CD molecules with theepoxide ring of ECH, resulting in glyceryl bridges between neighboringα-CD molecules in the confined space of 1D COF channel. It shouldbe noted that also reactions between ECH and nonreacted COF monomers might happen because the COFstructure is rather difficult to get 100% perfect during the membraneformation. These potential reactions would immobilize α-CDsonto the COF pore walls and promote the formation of linearly orientedα-CDs inside the COF pores. Finally, the LA-α-CD-in-TpPa-1membrane was obtained after a rinsing treatment.To realizethe pore-in-pore concept, α-cyclodextrin (α-CD) is selectedas the building block for ultramicropore channels inside the 2D ketoenamine-linked1,3,5-triformylphloroglucinol (Tp) 2O3 diskbecame crimson after the COF synthesis due to the characteristic colorof TpPa-1  mapping , indicating no detectable LA-α-CD-in-TpPa-1formed in the bulk ceramic substrate.The white α-Al surface 1a. MoreoFigure S1) and the prepared self-supporting COF layer , mainly due to the thinner thicknessof about 1.5 μm and much smaller amount compared to the Al2O3 disk which led to the dominating diffractionsignals of the Al2O3 corundum substrate.63 There are no obvious characteristicdiffraction signals of α-CD  in the LA-α-CD-in-TpPa-1 membrane, probably due to the lowcontent (about ∼11.8 vol%) and molecular-level distributionof α-CD molecules assembled inside the 1D nanochannels of TpPa-1.Otherwise, the diffraction peaks of the α-CD aggregates withthe cage-type structure65 should have been detectedas we have proven by studying a powder mixture of α-CD and TpPa-1. Attenuated Total Reflectance-FourierTransformed InfraRed (ATR-FTIR) spectra . The intensity of these two peaks in the LA-α-CD-in-TpPa-1membrane is relatively weak because of the low content of LA-α-CDin the TpPa-1 layer. Spatial arrangement of the LA-α-CD in themembrane could be exposed by fluorescence spectroscopy on the basisof the host–guest interaction between LA-α-CD (and/orα-CD) and a fluorescence probe such as rhodamine B. It followsfrom Figure S5 that red fluorescence can be clearlyobserved on the whole surface and cross-section of the LA-α-CD-in-TpPa-1membrane as compared to the α-CD-free TpPa-1 membrane, evidentlyindicating the existence of LA-α-CD (and/or α-CD).As shown in Figure S6b corresponding to Figure S6a) both display the evenly distributedether linkages (C–O–C) over the LA-α-CD-in-TpPa-1membrane as compared to the TpPa-1 powders  and TpPa-1 membrane without α-CD , confirming the uniformity of LA-α-CD (and/orα-CD) incorporated inside the TpPa-1 layer on a macroscopicscales. The full XPS survey spectra  indicate the presence of nitrogen, carbon, and oxygen in the LA-α-CD-in-TpPa-1membrane. The high-resolution spectrum of deconvoluted N1s  shows the characteristicenergy peaks of TpPa-1 matrix. From the high-resolution spectra ofO1s . It is worth noting thatthe BET surface areas of both TpPa-1 and LA-α-CD-in-TpPa-1 arecomparable to that of the reported TpPa-1 powders and TpPa-1 membranesin the literature.67 However, due to the large amounts of staggered and thus interruptedpore channels, the nitrogen adsorption is affected, and the LA-α-CD-in-TpPa-1and TpPa-1 layers usually show relatively low BET values comparedto powder samples . Notably,the experimental pore size distribution of the LA-α-CD-in-TpPa-1layer is concentrated in the ultramicroporous region of 0.3–0.5nm compared with the α-CD-free TpPa-1 . This finding could serve as compelling evidence for theLA of α-CD molecules to be the linear channel-type α-CDstructure in the compact TpPa-1 layer. These results collectivelydemonstrate the successful generation of the ultramicropore-in-nanoporeLA-α-CD-in-TpPa-1 membrane with the designed matreshka-likepore-channel structure (Raman and X-ray photoelectron spectroscopy (XPS)were performedto further detect the membrane structure. Surface and cross-sectionalRaman mappings .However, inside the confined space of the 1D channels of 2D COF, itcould be rationally inferred that the most possible case is the statisticallychannel-type linear arrangement in which α-CD molecules areconnected together and stacked on top of each other (head-to-heador head-to-tail orientation) by cylindrical columns . Moreover, the α-CD molecules in the linearLA-α-CD polymers may not be strictly aligned. In addition, determiningthe number of α-CD molecules assembled is indeed interestingbut also extremely difficult mainly due to the tiny size and contentwhich is often below the detection limit. We have tried a varietyof methods such as high-resolution scanning tunneling microscopy (STM)to figure out the specific shape of LA-α-CD in the membrane,but the results were negative owing to the low image contrast causedby the similar elemental composition to the TpPa-1. Despite this,whatever the length , the pore-in-porestructures induced by various channel-type LA-α-CD will be conduciveto creating selective transport pathways in the 1D pore channels ofCOF for the targeted gas molecules such as H2 through themembrane.It is worth mentioning that there are several possiblecases ofstructural arrangement for the LA-α-CD molecules . The fluxes of the single gases H2, CO2, CH4, C3H6, and C3H8 as well as equimolar (1:1) binarymixtures of H2 with CO2, CH4, C3H6, and C3H8 were testedat room temperature (298 K) and 1 bar, respectively. It can be seenthat the LA-α-CD-in-TpPa-1 membrane shows a single componentH2 permeance of 3077.3 GPU, which is much higher than thoseof the other gases . Thisdemonstrates the superior H2-permselective properties ofthe LA-α-CD-in-TpPa-1 membrane, which is expected to displaya desirable separation performance in mixed-gas permeation. The realselectivities (or separation factors) of the LA-α-CD-in-TpPa-1membrane for equimolar H2/CO2, H2/CH4, H2/C3H6, and C3H8 gas pairs can reach 34.8, 38.1, 144.6, and 169.2,respectively. A significant improvement in separation selectivityis observed as compared to that of the TpPa-1 membrane without LA-α-CD. Meanwhile, the LA-α-CD-in-TpPa-1membrane still has a high H2 permeance of ∼3000GPU during the mixed-gas permeation. This result further suggeststhe formation of an ultramicroporous structure with fast and selectivetransport channels for H2 in the LA-α-CD-in-TpPa-1membrane ratio from XPS), thereby leading to only a small mass transfer resistance.We also investigated the effect of the α-CD concentration inthe precursor solution on the membrane performance . As the α-CD concentration increases, theH2 permeance decreases gradually. Simultaneously, the separationselectivity of H2/CH4 went up first and thenstarted to descend when the α-CD concentration reached 2.1 mg/mL.A higher concentration of α-CD makes the COF layer more rigidand brittle, which is prone to have crack defects during the solventevaporation and drying process , resulting in a drop of selectivity.Gas-separation performance was measured following the Wicke–Kallenbachmethod 3aby pla2/CO2 and H2/CH4 mixtures was scarcely deteriorated.Considering practical applications, gas permeation was also conductedat higher temperature to investigate the thermal stability of ourmembrane. We find a gradual decline of selectivity in H2/CO2 separation with the increase of testing temperature, which is due to the strongeractivated diffusion of CO2 than H2 . Damage to the membranestructure, in terms of a thermal decomposition of TpPa-1 and α-CD,can be excluded from the data. The membrane remains stable at 180°C, and no performance degradation was observed after a continuousoperation over 70 h . In contrast,the α-CD-in-TpPa-1 membrane without LA chain formation throughECH treatment was also prepared and subjected to a long-term gas-permeationstudy. Both H2 permeance and separation selectivity ofthe H2/CO2 mixture descend during the testingprocess . A shifting and jogglingof the unbound α-CDs inside the COF nanopores interrupts andblocks the selective gas transport through the α-CDs, whichslowly form nonselective diffusion channels in the membrane. Thisfinding also indicates that an LA is critical and necessary to obtaina robust membrane for selective H2 separation followingour pore-in-pore concept.In addition, the LA-α-CD-in-TpPa-1 membraneexhibits a goodrunning stability during a 60 h long continuous gas-permeation measurement3d becaus2 and CO2 increased,and meanwhile, the H2/CO2 separation factordecreased first from 33 at 1 bar to 17 at 1.2 bar and then leveledoff with the further increase of feed pressure . The decrease of separation selectivity is probablyrelated to the flexibility of the channel-type LA-α-CD structure,which might slightly dilate the transport channels formed betweenthe inner wall of COF pore and the exterior wall of LA-α-CDunder pressurization, causing the penetration of more CO2 molecules. It is noteworthy that the cases such as structural damageand defects could be reasonably ruled out because the LA-α-CD-in-TpPa-1membrane exhibited an excellent pressure resistance even at 6 barin a cross-flow nanofiltration test  by using the water and Na2SO4 aqueous solutionas the feed, respectively . Moreover, the rejection rate can reach >99% toward variouswater-solubleorganic dyes with a molecule size larger than 1.1 nm  and also >80% toward monovalent,divalent, and trivalent ions  with hydrated ions diameters ranging from 0.6 to 1nm . However, under the same conditions, the TpPa-1membrane shows low rejections for some dyes such as acid fuchsin (29.2%),rose bengal (36.8%), and methylene blue (8.3%) and also exhibits lowrejection for some salts such as NaCl (48.3%). The obtained pore-sizedistributions  by rejectingneutral solutes of polyethylene glycol (PEG) with different molecularweight verified the ultramicropores (about 0.44 nm) of the LA-α-CD-in-TpPa-1membrane. In addition, the possibility of LA-α-CDα-CD-in-TpPa-1instead being a mixed matrix COF membrane with α-CD inclusionscan be rationally excluded based on the effective nanofiltration performance. These resultsfurther indicate the compacted structure and narrowed pore size inthe LA-α-CD-in-TpPa-1 membrane after incorporation of LA-α-CD.Despite a decline, the value of H2/CO2 separationselectivity keeps above 15 with the pressurization, and also the separationselectivity could be recovered to the previous value of about 30 afterrelease of the pressure. These findings suggest the good pressure-resistantproperty of the host–guest LA-α-CD-in-TpPa-1 membrane.Besides temperature, feed pressureis also an important factorinfluencing the membrane performance. For our LA-α-CD-in-TpPa-1membrane, the permeances of both H2/CO2 and H2/CH4 versus H2 permeance for our LA-α-CD-in-TpPa-1membrane and other types of membranes (see the detailed comparisonin Tables S3 and S4). In contrast to othermembranes, the LA-α-CD-in-TpPa-1 membrane exhibits high valuesin terms of both permeance and selectivity, demonstrating an anti-trade-offphenomenon. The overall performance far exceeds the Robeson upper-boundlimits for H2/CO2 and H2/CH4 mixtures,68 respectively, and belongsto the most powerful COF membranes. The excellent performance togetherwith the good stability could also provide circumstantial evidenceof fast and H2-preferential transport pathways within thelinear α-CD polymer-tailored COF nanochannels.Figures S27–S29) by using a similarsynthesis protocol as for the LA-α-CD-in-TpPa-1 membrane. Thegas permeation measurements were conducted at room temperature byusing an equimolar H2/CH4 mixture as feed . It can be seen that all of the membranesexhibit a very good H2 permeance higher than 2800 GPU.The H2/CH4 separation selectivities of the LA-α-CD-in-TBPa-1membrane, LA-α-CD-in-TBBD membrane, and LA-α-CD-in-TpBDmembrane could reach 30.6, 20.6, and 21.5, respectively. Moreover,their comprehensive performances are also competitive and higher thanmost of the existing COF gas membranes without α-CDs,30 illustrating the potential and broad applicability of this pore-in-porestrategy.To demonstratethe versatility of the pore-in-pore design concept,we prepared three other types of LA-α-CD-in-COF membranes . The simulationsshow two preferential transport pathways for H2 moleculesin the LA-α-CD-in-TpPa-1 channels,  and at the LA-α-CDs surface .These strong adsorptive interactions retard the transport of CO2 molecules and result in a low CO2 permeation,simultaneously narrowing this gap for the mobile H2 molecules.As shown in 2 molecules (18 out of 30 molecules)in the feed chamber could pass through the LA-α-CD-in-TpPa-1membrane to the permeate chamber within 1000 ps, accompanied by only13.3% of the CO2 molecules (4 out of 30 molecules), demonstratinga faster H2 permeation. Further, the H2 diffusioncoefficient could be calculated from the linear fitting of the MSDin 2 diffusivity. Thisfinding signifies that the simulated separation selectivity is 1.8times the experimental measurement (about 35). On the contrary, inan TpPa-1 channel without LA-α-CD , the transport of CO2 molecules atthe pore wall is retarded. However, at the center of the pore channelsthe diffusion of CO2 molecules is not affected. In thiscase, a large proportion of CO2 molecules together withH2 molecules can pass through the membrane. As expected,47% of the H2 molecules (14 out of 30 molecules) passedthrough but were accompanied by 43% of the CO2 molecules(13 out of 30 molecules) at the same time. Here, the calculated H2 diffusion coefficient is about 23 times larger than the CO2 one , which is 1.6times the corresponding experimental measurement (D(H2)/D(CO2) ≈ 14.5).However, a difference in performance between experimental measurementand MD simulation can be expected since the modeling structure cannotbe strictly consistent with that of the real membrane structure onthe macroscopic scale. For example, the low content of α-CDand the not strictly aligned ultramicropore structure will probablyresult in relatively low H2/CO2 selectivitiesin the experimental measurements. Despite this, the quotients of measuredselectivity and simulated selectivity for the LA-α-CD-in-TpPa-1membrane (∼1.8) and TpPa-1 membrane (∼1.6) are veryclose to each other. Meanwhile, the result of the simulated selectivityfor the LA-α-CD-in-TpPa-1 membrane being higher than that forthe TpPa-1 membrane is basically in agreement with the experimentalmeasurements. Likewise, the H2 molecules permeate fasterthrough the LA-α-CD-in-TpPa-1 channels along the same pathwaysmentioned above in the presence of CH4 molecules, as comparedto the permeation process inside the TpPa-1 channels . The simulations indicatethat the performance improvement of the pore-in-pore membrane is mainlyattributed to the competitive diffusion mechanism in the confinedultramicropore channels rather than to rigid size-sieving effects.Furthermore, these results imply that increasing the LA-α-CDcontent within the COF nanopores and maintaining the ordered structureof the host–guest confinement is crucial for the membrane discriminationaccuracy for molecular–selective gas separations.Apparently, the engineering of pore-in-pore channels by packingof linear CD polymers contributes to the improvement in gas-separationperformance of the COF membrane. To elucidate the separation mechanismon a microscopic scale, molecular dynamics (MD) simulations were carriedout to investigate the permeation behavior of equimolar Hmembrane S31. The membrane S31. The membrane S31. The 2 and CH4 but renderspreferential transport pathways for the H2 molecules. Owingto the competitive diffusion mechanism in the confined ultramicroporechannels, the linear assembly-α-CD-in-TpPa-1  and p-phenylenediamine(Pa-1)) membrane displays an ultrahigh H2 permeance andsignificantly enhanced separation selectivity for gas mixtures ascompared to the starting TpPa-1 membrane without α-CD inclusion.The excellent overall performances combined with a high stabilityrecommend the pore-in-pore COF membranes for advanced H2 purification and production. In consideration of a certain generalizability,this research complements the existing design strategies of ultramicroporousCOF membranes and could facilitate their advancement in the fieldof precise molecular separations. The preparation of linear arrangementsof guest species in the nanochannels of COFs is also of interest forthe preparation of functional host–guest materials.We have developed a pore-in-pore strategyfor packing linear α-cyclodextrin(α-CD) polymers into the COF nanochannels to engineer COF membraneswith a matreshka-like pore structure suitable for gas separation.The formation of ultramicropore-in-nanopore channels retards the diffusionof bulky molecules such as COp-phenylenediamine (Pa-1) , benzidine (BD) ,1,3,5-triformylphloroglucinol (Tp) , 1,3,5-triformylbenzene(TB) , acetic acid , α-cyclodextrin, 3-aminopropyltriethoxysilane , epichlorohydrin , ethanol , sodium hydroxide , hydrochloricacid , polyethylene glycols with various molecularweights . Sodiumchloride , sodium sulfate , sodium carbonate ,and gadolinium chloride  were providedby Sinopharm Chemical, China. Dyes including chrome black T, methylblue, acid fuchsin, congo red, rose bengal, and methylene blue (MEB)were supplied by Shanghai Macklin Biochemical Technology, China. Porousasymmetric α-Al2O3 disks  as substrateswere purchased from Fraunhofer IKTS, Germany.All chemicals and materialswere used as received without further purification: 2O3 substrate was activated by usingHCl aqueous solution (1 M), and then the surface was modified withAPTES (2 mM in toluene) at 110 °C for 2 h under argon. The LA-α-CD-in-TpPa-1membrane was synthesized via an α-CD-embedded interfacial polymerizationfollowed by a linear assembly (LA). First, 24 mg of Pa-1 and 20 mg of α-CD were dissolved into 12 mL ofultrapure water, and then 2 mL of acetic acid aqueous solution (3M) was added to form the solution A. After that, 31.5 mg of Tp wasdissolved into 14 mL of toluene to form solution B. It should be notedthat both solution A and solution B were prepared under argon atmosphere.Before interfacial polymerization, the amino-α-Al2O3 substrate was thoroughly immersed into solution A untilit was saturated. Subsequently, the amino-α-Al2O3 substrate was fixed in between solution A and solution Bwith a homemade device, which was then horizontally placed at 120°C for 72 h to allow the growth of the α-CD-in-TpPa-1 layeronto the amino-α-Al2O3 substrate. Aftercooling, the formed α-CD-in-TpPa-1 membrane was washed withwater and ethanol and dried at 120 °C overnight. Finally, theα-CD-in-TpPa-1 membrane was soaked into the prepared ECH alkalinesolution  solution) at 50 °Cfor 8 h to cross-link the packed α-CDs. This process is namedas LA in this study. The LA-α-CD-in-TpPa-1 membrane was obtainedafter a thorough rinsing by ultrapure water. It should be pointedout that the α-CD used was structurally stable in the weak acidicenvironments during the interfacial polymerization, and the membranewas stable in the alkaline environments during the cross-linking ofthe packed α-CDs because of the short immersion time.The porousα-AlFor comparison, the TpPa-1 membrane without α-CD and the α-CD-in-TpPa-1membrane were synthesized by using a similar procedure as mentionedabove. Three other types of LA-α-CD-in-COF membranes were preparedby using a similar protocol as for the LA-α-CD-in-TpPa-1 membrane.The main difference is that the LA-α-CD-in-TBPa-1 membrane wassynthesized from 24 mg of Pa-1, 20 mg of α-CD, and 24 mg ofTB; the LA-α-CD-in-TBBD membrane was synthesized from 27.6 mgof BD, 20 mg of α-CD, and 16 mg of TB; the LA-α-CD-in-TpBDmembrane was synthesized from 27.6 mg of BD, 20 mg of α-CD,and 21 mg of Tp.–1, a voltage of 40 kV, and current of 40 mA. X-rayphotoelectron spectroscopy (XPS) spectra were recorded on a ThermoScientific K-Alpha+ spectrometer using Al Kα radiation as theenergy source at a voltage of 15 kV and current of 15 mA. The pressurein the instrumental chamber was about 5 × 10–9 mbar. The binding energies were calibrated on C 1s (284.8 eV). Attenuatedtotal reflectance-Fourier transformed infrared spectra (ATR-FTIR)in a wavenumber region of 400–4000 cm–1 witha resolution of 0.4 cm–1 were obtained by usinga spectrometer (Agilent Technologies Cary 630 FTIR). The ATR-FTIRspectrum of the membrane samples was obtained from the powders shavedoff from the selective layer on the α-Al2O3 substrate. Raman spectra were acquired by a Horiba LabRAM HR Evolutioninstrument using an Ar+ laser at 514.5 nm. Fluorescence imaging wasrecorded on an Olympus IX71 microscope at an excitation wavelengthof 546–560 nm. Before measurement, membrane samples were submergedin an aqueous rhodamine B solution and subjected to the treatmentsincluding rinsing with water and drying. N2 adsorption–desorptionmeasurements were performed at 77 K on a Micromeritics ASAP2460 surfacearea and pore distribution analyzer instrument. Before the adsorptionexperiments the powdered samples were vacuum degassed at 120 °Cfor 10 h. The isotherms were analyzed by using the Brunauer–Emmett–Tellermethod and the t-plot micropore volume method.Micromorphologies of the membranesand powdered samples were observed by using a JEOL JSM-6700F instrumentwith a cold field emission gun operating at 2 kV and 10 mA. Beforemeasurement, all samples were coated with a 15 nm thick gold layerin vacuo to reduce the charging effects. Energy-dispersive X-ray spectroscopy(EDXS) mapping and elemental analysis of the membrane cross sectionwere conducted on the scanning electron microscopy (SEM) at 15 kV,10 mA and 15 mm lens distance. For transmission electron microscopy(TEM) measurements, a small drop of aqueous solution of mashed membrane,LA-α-CD, or α-CD was dripped on an ultrathin carbon supportfilm and dried, and then the specimen was observed with a JEM2100Fmicroscope. X-ray diffractometer (XRD) patterns were recorded on aBruker D8 Advance diffractometer  at room temperature, and each XRD pattern was acquiredfrom 3° to 35° of the diffraction angles at a rate of 0.01°sFigure S13) sealed with rubber O-rings. N2 was used as the sweep gas set at 50 mL min–1 during the measurement process, and the pressures at both sideswere kept at about 1 bar. It should be noted that the feed pressureis always a little bit larger than the permeate side to avoid thepossibility of back flow of the sweep gas. Before gas permeation,an on-stream activation was carried out at 393 K to get rid of potentialsolvent molecules inside the pores of the membrane by using an equimolarH2/CO2 mixture as the feed. For the measurementof single gas permeation, both feed and sweep flow rates were setat 50 mL min–1. For the measurement of mixed-gaspermeation, a series of equimolar (1:1) binary gas mixture includingH2/CO2, H2/CH4, H2/C3H6, and H2/C3H8 were applied to the feed side of the membrane, andthe feed flow rate of each gas was kept constant at 25 mL min–1. A calibrated gas chromatograph (HP 6890B) was usedto detect the component concentration on the permeate side of themembrane when the measurement system ran stable.The prepared membrane wasplaced inside a laboratory-made gas-permeation apparatus (i (Pi) was calculated as follows (Ni represents the permeation rate of component i (mol s–1), A is the effectivemembrane area (m2), and Δpi is the partial pressure difference of component i (Pa). Fi denotesthe molar flux of component i (mol m–2 s–1). Permeance of each membrane was calculatedby the average of five data points. The GPU is the unit of gas permeance(1GPU = 3.3928 × 10–10 mol m–2 s–1 Pa–1).The permeanceof component  follows 11where Ni (Pi) divided by the permeance of component j (Pj) in thesingle-gas permeation. The real selectivity  of an equimolar binary gas mixture (or separation factor)was calculated as follows . A dye aqueous solution (100 mg/L) or a salt aqueous solution(1000 mg/L) as the feed was circulated by using a plunger pump, andthe operating pressure was set at 4 bar. The measurement began whenthe filtration system reached a steady state after a period of operation.The water flux (L m–2 h–1) andpermeance (L m–2 h–1 MPa–1) were calculated by normalizing the permeate volume collected duringthe time t. The concentration of dyes and salts inthe feed (Cif) and permeate(Cip) was monitored bya UV–vis detector (UV BlueStar A) and a conductivity meter(KEDIDA CT3030), respectively. Accordingly, the rejection  of the dyes or saltswas calculated as follows  composed of nine-layered nanosheets with a thickness of approximately2.7 nm along the z-axis was conducted as shown in Figure S31a. Based on the most possible caseof statistically channel-type linear arrangement that we have analyzed,the atomic structure of LA-α-CD-in-TpPa-1 is built by incorporatinga linear α-CD polymer consisting of three cross-linked α-CDsinto one nanochannel of the TpPa-1, as illustrated in Figure S31b. To some extent, it represents theelementary mass transfer unit in the 1.5 μm-thick LA-α-CD-in-TpPa-1membrane. MD simulation was carried out by a Materials Studio software6.0 package with a COMPASS force field.70 A typicalsimulation box with a dimension of 45.1 Å × 45.1 Å× 139.4 Å was established and separated into two chambersby the TpPa-1 layer or LA-α-CD-in-TpPa-1 layer from the middle.An equimolar mixture of H2/CO2 or H2/CH4 (30 molecules for each component) was added to theleft chamber, and a vacuum was applied on the right. An NVT  ensemble was employed forsimulation, and system optimizing was implemented before diffusionsimulation. The initial velocities were random, and the Andersen thermostatwas employed to maintain a constant simulation temperature of 298.0K. The MD simulation was performed for 1 ns with a time step of 1fs using the Forcite module. The diffusion coefficient is relatedto the mean square displacement (MSD) and simulation time. The diffusioncoefficients of the H2, CO2, and CH4 were calculated from the slope of the straight line fitted fromthe MSD versus simulation time .The eclipsed atomicstructure of TpPa-1 (


Pancreatic ductal adenocarcinoma remains one of the most serious malignancies and a leading cause of cancer-related deaths worldwide. There are no effective screening methods available so far, even for high-risk individuals. At the time of diagnosis, impaired glucose metabolism is present in about 3/4 of all patients. Several types of diabetes mellitus can be found in pancreatic cancer; however, type 2, pancreatic-cancer-associated type 3c, and diabetes mellitus associated with non-malignant diseases of the exocrine pancreas (with a reduction or loss of islet-cell mass) are the most frequent ones. This paper proposed a distinct approach to older subjects with new-onset diabetes mellitus with possible pancreatic cancer. It could improve the current unsatisfactory situation in diagnostics and subsequent poor outcomes of treatment of pancreatic ductal adenocarcinoma.Background: Pancreatic ductal adenocarcinoma (PDAC) is associated with a very poor prognosis, with near-identical incidence and mortality. According to the World Health Organization Globocan Database, the estimated number of new cases worldwide will rise by 70% between 2020 and 2040. There are no effective screening methods available so far, even for high-risk individuals. The prognosis of PDAC, even at its early stages, is still mostly unsatisfactory. Impaired glucose metabolism is present in about 3/4 of PDAC cases. Methods: Available literature on pancreatic cancer and diabetes mellitus was reviewed using a PubMed database. Data from a national oncology registry (on PDAC) and information from a registry of healthcare providers  were obtained. Results: New-onset diabetes mellitus in subjects older than 60 years should be an incentive for a prompt and detailed investigation to exclude PDAC. Type 2 diabetes mellitus, diabetes mellitus associated with chronic non-malignant diseases of the exocrine pancreas, and PDAC-associated type 3c diabetes mellitus are the most frequent types. Proper differentiation of particular types of new-onset diabetes mellitus is a starting point for a population-based program. An algorithm for subsequent steps of the workup was proposed. Conclusions: The structured, well-differentiated, and elaborately designed approach to the elderly with a new onset of diabetes mellitus could improve the current situation in diagnostics and subsequent poor outcomes of therapy of PDAC. Pancreatic cancer remains one of the most serious malignancies and a leading cause of cancer-related deaths worldwide . Accordihttps://pubmed.ncbi.nlm.nih.gov) (accessed on 9 April 2023), there are nearly 4200 records on “pancreatic cancer + diabetes mellitus”. Our aim was not to provide a comprehensive literature review or to try to create a meta-analysis based on the very heterogeneous studies available so far. We focused instead on providing an explanation of the different types of diabetes mellitus associated with pancreatic cancer and outlining a possible future basis for PDAC screening and/or diagnosis at the early stage of the disease.At the time of PDAC diagnosis, impaired glucose metabolism is present in about 3/4 of all patients ,10,11,12First of all, it is important to briefly review the current terminology, with particular emphasis on the difference between screening, early diagnosis, and diagnosis at an early stage of PDAC.Screening refers to the use of simple tests across a healthy population to identify those individuals who have a disease but have been asymptomatic in relation to that particular disease so far. Based on the existing evidence, average-risk population screening can only be advocated for cervical, breast, and colorectal cancer .Many different methods and possible markers for PDAC screening have been proposed, including microRNA and other non-coding RNAs, cell-free DNA (cfDNA), circulating tumor DNA (ctDNA), lipidomic profiling and other metabolomics, combined spectroscopy analyses , exosomes, S100 proteins, CEMIP  and other proteomics, different enzymatic activities , or multiple metabolites  ,52,53,54Average-risk sporadic PDAC is responsible for about 90% of all cases of pancreatic cancer. The rest comprises high-risk subjects with a family history of PDAC (at least two first-degree relatives with PDAC), underlying inherited diseases  and/or patients with known genetic mutations investigated due to another indication  ,65,66,67A unique prospective long-term follow-up study enrolled 354 individuals at high risk for PDAC (based on genetic factors or family history). Overall, 24 of 354 patients (7%) had neoplastic progression (14 PDAC and 10 high-grade dysplasia) over a 16-year period. Magnetic resonance imaging (MRI) and endoscopic ultrasound (EUS) were the two major methods used for a follow-up ,65,66,68The Japanese Pancreas Society, AGA , and ASGE  have recently published guidelines on screening and early diagnosis of PDAC in high-risk subjects ,69,70,71European evidence-based guidelines are available for the diagnosis and management of pancreatic cystic neoplasms . MucinouThe preferred staging system used for all pancreatic cancers is the TNM classification  of the combined American Joint Committee on Cancer and the Union for International Cancer Control . High-grEarly detection does not necessarily mean diagnosis of early-stage PDAC. Early diagnosis programs aim at reducing the proportion of patients who are diagnosed at a late stage. They have three main components: increased awareness of the first signs of cancer ; improved accessibility and affordability of diagnosis and treatment services, and improved referral from the first to secondary and tertiary levels of care . Unique Great attention has been paid to the relationship between diabetes mellitus and pancreatic cancer. Many large studies have addressed this issue. A Nurses’ Health Study and a Health Professionals Follow-Up Study (with repeated assessments over 30 years) enrolled 112,818 women and 46,207 men. In total, 1116 incident cases of pancreatic cancers were identified. New-onset diabetes mellitus (HR 2.97) accompanied by weight loss  was associated with a substantially increased risk of developing pancreatic cancer. Older age, previous “healthy weight,” and no intentional weight loss elevated this risk further . DiabeteMajor shortcomings of a substantial amount of studies are caused by the fact that they do not distinguish (define) particular types of diabetes mellitus, mainly type 2, from others. Notably, “pancreatogenic diabetes mellitus” ,88,89 isAccording to the American Diabetes Association (ADA), diabetes mellitus is classified into four major groups: type 1, type 2, specific types, and gestational diabetes mellitus . Apart fRegarding a practical clinical approach, the current pathophysiology basis should be maintained as it is determinative for both diagnosis and therapy. Thus several types of diabetes mellitus can be found in PDAC; however, type 2, PDAC-associated type 3c, and diabetes mellitus associated with non-malignant diseases of the exocrine pancreas (with a reduction or loss of islet-cell mass) are more frequent ,97 . It is characterized by insulin resistance as the first event, resulting in hyperinsulinemia ,94. LongBased on a meta-analysis, therapy of type 2 diabetes using metformin could reduce the risk of PDAC by 18% compared with other treatments . HoweverPDAC-associated type 3c diabetes mellitus has a typical onset in older subjects (over 60 years of age) . This tyPDAC-associated type 3c diabetes is characterized by a decreased secretion of insulin and increased insulin resistance ,101. ThiThe pathogenesis of pancreatic cancer-associated diabetes has not been fully elucidated yet; see References ,101 for Insulin resistance in PDAC is presumed to occur at the postreceptor level. In searching for the exact mechanism, islet amyloid polypeptide (IAPP) was proposed as a putative mediator. The serum level of IAPP was higher in pancreatic cancer patients than in the diabetic population or healthy controls . IAPP isOne-third to one-half of type 3c diabetes mellitus might be resolved, or at least improved, after successful surgical resection of PDAC, despite the reduction of islet-cell mass resulting from the surgery . A studyThis type of diabetes mellitus is characterized by decreased insulin secretion and normal insulin sensitivity. It is a secondary complication of different advanced chronic non-malignant diseases of the pancreas, usually preceded or associated with the exocrine pancreatic insufficiency, with a reduced or lost islet-cell mass  . Alone, We strive to propose a set of investigations that would be feasible, accessible, and affordable on a broad population basis (not just for research purposes). The diagnosis of PDAC-associated type 3c diabetes, when the pancreatic disease is not overt, can be challenging. Therefore, new-onset diabetes in subjects over the age of 60 and associated with weight loss should prompt consideration of this type of diabetes. Rapid progression of hyperglycemia or an early need for insulin should also prompt to consider this diagnosis .Diagnosis of PDAC-associated type 3c diabetes mellitus is based on a decrease in insulin production  and an increase in insulin resistance , see https://www.omnicalculator.com/health/homa-ir, (accessed on 27 June 2023) The normal value of HOMA-IR is <2.5 [0) + log(G0)], where I0 is the fasting insulin (mU/mL), and G0 is the fasting glucose concentration (mg/dL). The normal value of QUICKI is >0.45 [Several insulin resistance indices were proposed ,133,134. is <2.5 . QUICKI is >0.45 .An increased glucagon/insulin ratio is another marker of insulin resistance . InvestiAt present, there is no feasible, effective, and reliable population-based program for the diagnostics of PDAC. Continuously rising incidence and ongoing poor outcomes in PDAC treatment mean that a new strategic approach is required urgently. A program based on a distinct attitude to subjects with new-onset diabetes mellitus of different types might be one way, at least according to data from the Czech Republic . The incidence of pancreatic cancer in the Czech Republic is the 3rd highest in Europe, with 2332 (2018) and 2466 (2020) new cases per year . The median age at diagnosis was 70 (interquartile range 63–78) . IncidenLess than 20% of newly diagnosed PDAC patients undergo surgical resection with curative intent ,144. AboNew-onset diabetes mellitus, together with significant weight loss, serves as an important early discriminating factor . A fullyShould transabdominal ultrasound be recommended as the first step in the vast majority of new-onset diabetes mellitus cases, such an approach needs to be supported by a feasibility estimation and capacity balance sheet. According to the Institute of Health Information and Statistics of the Czech Republic, about 3,000,000 transabdominal ultrasound investigations are performed in the Czech Republic per year, with a slightly increasing trend within the past five years  . Even inLast but not least, it is necessary to mention the irreplaceable role of multidisciplinary teams. All PDAC cases must be evaluated and appraised by a multidisciplinary team (MDT) that can decide the further course, follow-up, and planned therapy.We are aware of the possible limitations of our concept. A prospective multicenter study is needed to validate the efficacy of this approach. Prompt access to CT imaging (pancreatic protocol) and/or MRI and/or EUS (with fine-needle aspiration/biopsy) might be a limiting factor. Our concept does not cover younger patients and/or subjects without diabetes mellitus or individuals with prediabetes .A structured, well-differentiated, and elaborately designed approach to older patients (over 60 years of age) with new-onset diabetes mellitus could improve the current unsatisfactory situation in diagnostics and subsequent poor outcomes of treatment of PDAC. Our concept includes such an algorithm. Further studies are warranted.


Arabidopsis thaliana as queries. These 286 NLR genes contained at least one NBS domain and LRR domain. Phylogenetic and N-terminal domain analysis showed that these NLRs could be separated into four subfamilies (I-IV) and their promoters contained many cis-elements in response to defense and phytohormones. In addition, transcriptome analysis showed that 22 NLR genes were up-regulated after infected by Green Peach Aphid (GPA), and showed different expression patterns. This study clarified the NLR gene family and their potential functions in aphid resistance process. The candidate NLR genes might be useful in illustrating the mechanism of aphid resistance in peach.Resistance genes (R genes) are a class of genes that are immune to a wide range of diseases and pests. In planta, NLR genes are essential components of the innate immune system. Currently, genes belonging to NLR family have been found in a number of plant species, but little is known in peach. Here, 286 NLR genes were identified on peach genome by using their homologous genes in The online version contains supplementary material available at 10.1186/s12870-023-04474-7. The plant innate immunity system ensures normal growth during pathogen infection . Plants NRG1 (DQ054580.1) in tobacco and ADR1 (AT1G33560.1) in Arabidopsis thaliana can both regulate the accumulation of the defense hormone salicylic acid during the immune response, and ADR1 can also be used as “auxiliary NBS-LRR” to transduce specific NBS-LRR receptors during ETI [Physcomitrella patens, Marchantia polymorpha, and sphagnum fallax respectively, but the functions of these bryophyte-specific NLR subclasses have not yet been explored [NLR genes are the most important R genes in plants . The pro1 AT1G3350.1 in ArG1 DQ05450.1 in toexplored –11.Arabidopsis thaliana, it was identified that the NBS domain usually contains 8 conserved motifs [tomato I-2 resulted in continuous activation [RPM1 and other NLR genes in Arabidopsis thaliana showed that the proteins were inactivated [Listeria and Streptococcus, can integrate into host cells by encoding proteins with LRR domains [The NB-ARC structure (NBS) domain, belongs to the signal transducing ATPase multi-structural domain (STAND) superfamily , which hd motifs , includid motifs . Kinase tivation . In the ctivated . The leuctivated . Therefo domains .Rpi-blb2 confer broad-spectrum resistance to pathogen isolates in potato [Mi-1.2 is similar to Rpi-blb2, it has specific resistance to root knot nematodes and aphids in tomato [Adnr1 [RMES1 locus which contains five NLR genes on sorghum genome were predicted, and proven resistance to Melanaphis sacchari [Dp-fl locus, which confers resistance to Dysaphis plantaginea contains 19 genes acting as R-genes, 2 of which are NLRs in Malus pumila [Plants rely on NLR protein to respond to invasive pathogens and activate the immune response, so as to obtain resistance to bacteria, viruses, nematodes and pests . In prevn potato . Mi-1.2 n tomato . In gramo [Adnr1 . The RMEsacchari . In addis pumila .Myzus persicae, GPA) is the most harmful pest during peach production. It can stab and suck the new shoots and leaves, resulting in curling leaves, growth limitations. It can also secrete honeydew to spread viruses between species. In the last decades, several genetic loci conferring resistance to aphids have been identified and mapped on peach genome. Most of genes belong to the resistance genes encoding NLR proteins [Rm3 locus were identified [Peach is the fourth largest deciduous fruit crop in the world and has valuable nutrition . Green Pproteins . In peacentified . HoweverIn this study, we analyzed the NLR gene family in peach. A total of 286 NLR genes were identified, and their chromosome location, phylogenetic relationship, gene structure, conserved domains and promoter cis-elements were analyzed. Transcriptome analysis showed that the expression of 22 identified NLR genes was significantly up-regulated after GPA infestation. The results would provide a basis for further study on the function of NLR genes in aphid resistance.Arabidopsis thaliana were used as queries to find out the candidate genes in peach using the NCBI-Blastp toolkit. Then, their protein domains were further analyzed, especially the number of NBS and LRR domain. Finally, 286 NLR genes were selected in this study, which showed at least one NBS and LRR domain. These NLR genes are unevenly distributed on peach chromosomes, most of which are present on chr.1 (14.3%), chr.2 (25.52%) and chr.8 (27.27%)  to 2026 (Prupe.7G065400), with an average length of 1055. The molecular weight ranged from 48041.58 Da (Prupe.4G236500) to 230015.7 Da (Prupe.7G065400), with an average of 120157.56 Da. The isoelectric point of these NLR proteins ranged from 5.14 (Prupe.8G110800) to 9.61 (Prupe.3G040800), with an average value of 6.99, indicating that peach NLRs are mostly neutral protein , which included 153, 104, 11, 18 peach NLR genes respectively  phylogenetic tree was constructed using protein sequences of peach NLRs and 20 reported NLR genes in According to the differences in N-terminal domain, the subfamilies I-III were mainly characterized as CNL, TNL and RNL respectively, although some NLRs without N-terminal domain were also clustered in subfamily I and II Fig. . By furtPrupe.4G236500) has 3 Exons and no UTRs, much simpler than the longest (Prupe.2G118000) (4 Exons and 3 UTRs). .Gene structure analysis of NLR gene family showed that peach NLR genes contained many Exon and UTRs, and there were significant differences among different subfamilies. The average numbers of Exon and UTRs of these NLR genes was 4.69 and 4.47. Besides, the numbers in subfamily I  was mostly less than II  Table , while mPrupe.1G389500/Prupe.7G138500, Prupe.1G541300/Prupe.8G077100, Prupe.2G055200/Prupe.2G066600, Prupe.2G057100/Prupe.2G068000, Prupe.2G040500/ Prupe.2G053700, Prupe.2G043000/ Prupe.2G504200, Prupe.2G045200/Prupe.2G055200, Prupe.2G055200/Prupe.2G068900, Prupe.2G057100/Prupe.2G068000) were identified, indicating duplication was a major mode of gene expansion . A total of 1289 results were predicted, including 20% in cytoplasm, 17% in plasma membrane, 15% in chloroplast, and relatively few in other organelles , which had the closest phylogenetic relationship with three types Arabidopsis thaliana NLR genes respectively were cloned into the pCAMBIA1300 vector fused with GFP reporter. The results showed that all three types of NLR were localized both in nucleus and cytoplasm . Totally, 14 types of cis-elements were mainly enriched in these promoters, including 5 types of plant hormones response elements , 3 types of stress response elements  and 6 types of growth related response elements  . Among the total elements, plant hormone elements accounted for 35.3%, stress response elements accounted for 48.6%, and growth related elements accounted for 16.1%. In addition, heat map showing the number of cis-elements in each NLR genes was further constructed, and the results showed that the most enriched cis-element was light. Hormone associated element were also greatly enriched in these promoters, such as MeJA, ABA, SA, which indicated that NLR might participate in stress triggered signaling pathways. However, no significant differences in the number and distribution of promoter elements between different subfamilies were found  showed much higher expression levels than the others , and then rapidly decreased to the normal level. Only a few genes showed lower expression . The expression of most genes not infected by aphids did not change significantly with time, only 3 genes  were highly expressed , Oryza sativa (508), Glycine max (429), Solanum tuberosum (438), Populus (416), Gossypium spp (355) [TIR-LRR, NBSCC-LRR and NBS-LRR  , 45. Phyine max 49, Solanupp (355) . AccordiPopulus 46, GossypThe localization of plant NLR proteins might be associated with the localization of effectors . In geneMost of plant immune responses are accompanied with the release of phytohormones . SalicylPrupe.1G217900, Prupe.1G545200, Prupe.2G060400, Prupe.4G224500, Prupe.5G019000, Prupe.7G065500, Prupe.7G138600, Prupe.8G023100 and Prupe.8G023800 were highly expressed after 3 h of GPA infection. Prupe.2G022500, Prupe.2G283300, Prupe.5G025600 and Prupe.7G139100 were highly expressed after 6 or 12 h GPA infection. Tissue specific expression analysis showed that peach NLR genes was mainly expressed in root, leaf and stem, indicating their roles in disease and insect resistance . Using NLR genes in Arabidopsis thaliana as queries, the homologous NLR genes in peach were identified using Blastp tools in NCBI and the NBC and LRR domains were checked manually to get the final set of peach NLR genes. Structural domains were analyzed using Pfam (http://pfam-legacy.xfam.org/) [The protein sequences of NLR genes in am.org/) . Physicoam.org/) .https://phytozome-next.jgi.doe.gov/) and chromosome length information were download from JGI . The chromosome annotation of peach NLR gene family members were extracted using TBtools and mapped on chromosome [The peach genome annotation file  [http://gsds.gao-lab.org/) [https://meme-suite.org/meme/tools/meme) was used to predict and analyze the conserved protein motifs [Arabidopsis thaliana were analyzed using MCScanX software and mapped using TBtools [The phylogenetic tree of peach NLRs was constructed using MEGA11 software, and was viewed using evolview online website (olview/) . Chromosab.org/) . Gene stn motifs . The basn motifs . Genome- TBtools .pCAMBIA1300 vector fused with GFP under CaMV 35 S promoter , Then, the recombined constructs were transferred into Agrobacterium tumefaciens GV3101 for transient overexpression in tobacco leaves using previously described methods [Three peach NLR genes represent the main types of TNL, CNL and RNL were selected according to the phylogenetic tree. Their CDS sequences were obtained from NCBI and were cloned into  methods . GFP rephttps://www.rosaceae.org/) and submitted to PLANTCARE database for promoter element prediction [The promoter sequences of 286 peach NLR genes (2 kb upstream of the 5’UTR) were download from Genome Database for Rosaceae  and first-strand cDNA was synthesized using PrimeScript first-strand cDNA synthesis kit . Real-time quantitative polymerase chain reaction (qRT-PCR) was performed on ABI7500 system using SYBR premix ExTaq  with the following procedure: 95 °C for 5 min, followed by 45 cycles at 95 °C for 10 s, 58 °C for 10 s and 72 °C for 20 s. The relative expression level was calculated by 2T method . PrimersBelow is the link to the electronic supplementary material.Supplementary Material 1


The reason for the enhancing tribological performance was that, on the one hand, PEEK fibers have a high strength and modulus which can enhance the specimens at lower temperatures; on the other hand, molten PEEK at high temperatures can also promote the formation of secondary plateaus, which are beneficial for friction. The results in this paper can lay a foundation for future studies on intelligent RBFM.Resin-based friction materials (RBFM) are widely used in the fields of automobiles, agriculture machinery and engineering machinery, and they are vital for safe and stable operation. In this paper, polymer ether ketone (PEEK) fibers were added to RBFM to enhance its tribological properties. Specimens were fabricated by wet granulation and hot-pressing. The relationship between intelligent reinforcement PEEK fibers and tribological behaviors was investigated by a JF150F-II constant-speed tester according to GB/T 5763-2008, and the worn surface morphology was observed using an EVO-18 scanning electron microscope. The results showed that PEEK fibers can efficiently enhance the tribological properties of RBFM. A specimen with 6 ωt% PEEK fibers obtained the optimal tribological performance, the fade ratio was −6.2%, which was much higher than that of the specimen without the addition of PEEK fibers, the recovery ratio was 108.59% and the wear rate was the lowest, which was 1.497 × 10 Phenolic resins are widely used in the industries of adhesives, flame retardant materials and friction materials because of their excellent acid resistance, mechanical properties and high temperature resistance ,2. HowevPEEK is a kind of semi-crystalline polymer that has an excellent temperature resistance (the glass transition temperature is 143 °C and the melting point is 343 °C) . Its thePEEK has good tribological properties. As a reinforcement, Crosslinking Solidification between PEEK and the phenolic matrix has a negative influence for tribological properties and temperature perception, thus limiting its further application . In addi3AlC2/Cu composites with a sandwich structure. During friction, GO and Ti3AlC2 synergistically promote the formation of a continuous, compact and lubricating tribo-layer on the worn surface and enhance the wear resistance. Lekai Li [An effective method for the structure design of composites is the granulation technique . The comLekai Li  investigThis paper presents an intelligent friction material that can regulate the microstructure of the friction interface through the perception of temperature. The specimens are fabricated by step feeding, wet granulation and particle coating technology and hot-pressing, which can physically isolate the phenolic resin from PEEK fibers to prevent crosslinking solidification. Specimens were subjected to tribological tests and worn surface characterization to study the relationship between the tribological behavior and the PEEK fiber content, which could provide data information for product development in industry and lay a foundation for the development of intelligent tribological materials.The content of RBFM in this paper is shown in PEEK fibers were treated with Silane Coupling Agent . The composition of the SCA solution is shown in The first step was the mixing of raw materials. Fibers including PEEK fibers, Sepiolite fibers and Compound Mineral fibers were thrown into an Electrical Blender  for 3–5 min to increase dispersion. After dispersion, all the other compositions except for phenolic resin were thrown into a Compact Rake Blender  for 8–10 min to obtain the mixture of the raw materials.The second step was wet granulation, which can separate PEEK fibers and phenolic resin physically to avoid crosslinking solidification. The third step was hot-pressing. Granules were molded for 10 min at 160 °C under 45 MPa by a hot compression machine , according to our previous study ,20,21. TThe tribological performance of RBFM was tested using a Constant-Speed Tester  according to GB/T 5763-2008. μ of the specimens was calculated according to Equation (1) [f represents the friction force (N); NF is the normal pressure (N); r is the distance between the rotation center and the sample center; n is the number of revolutions (5000); A is the surface area (A = 625 mm2); d1 and d2 are the initial and final thickness of the sample, respectively.The COF tion (1) , and thetion (1) .(1)μ=fFFadeF) and recovery ratio (RecoveryF) are calculated according to Equation (3) and Equation (4), respectively.μCF100° and μCF350° represent the COF in the fade test at 100 °C and 350 °C, respectively, and μR100°C represents the COF in the recovery test at 100 °C.The tribological test was divided into two stages: a fade test and recovery test. The fade ratio  at 20 kV.The microscopic morphology of the PEEK fiber is shown in The result of the fade test was summarized in From the results in From the result in Combining the results in Combining the results in As shown in The result of the wear rate is shown in −7 cm3 × (N × m)−1, which was 51.1% lower than that of RBFM-1.In summary, the addition of 6 ωt% PEEK fibers provides the best compromise of tribological properties. On one hand, the addition of 6 ωt% PEEK fibers leads to a higher fade resistance and recovery performance, which can ensure the stability of the braking; on the other hand, it can also significantly improve the service life of RBFM and ensure the safety of braking.Friction is determined by the contact area condition, which is composed of hard materials and the compaction of wear debris around them  ,47. PlatThe microscopic morphology of the worn surface of RBFM-1 was shown in The microscopic morphology of the worn surface of RBFM-2 is shown in In summary, intelligent RBFM were fabricated by wet granulation, which could perceive the friction interface temperature and regulated the microstructure of the friction interface during braking. Specimens with 6 ωt% PEEK fibers had the best fade resistance and the lowest wear rate, and the stability of the COF was greatly improved. The main reason is that the high strength and modulus of the PEEK fibers enhanced the strength of the RBFM at lower temperatures, and the molten PEEK at high temperatures could effectively adhere wear debris, thus promoting the formation of secondary plateaus, which provided stable and continuous friction. Thus, PEEK fibers are a promoting intelligent reinforcement of RBFM. In the near future, a further study will be conducted to investigate the mechanical properties of PEEK fibers-reinforced RBFM.


Single use ureteroscopes are a technological innovation that have become available in the past decade and gained increased popularity. To this end, there are now an increasing number of both benchside and clinical studies reporting outcomes associated with their use. Our aim was to deliver a narrative review in order to provide an overview of this new technology.A narrative review was performed to gain overview of the history of the technology's development, equipment specifications and to highlight potential advantages and disadvantages.Findings from preclinical studies highlight potenial advantages in terms of the design of single use ureteroscopes such as the lower weight and more recent modifications such as pressure control. However, concerns regarding plastic waste and environmental impact still remain unanswered. Clinical studies reveal them to have a non inferior status for outcomes such as stone free rate. However, the volume of evidence, especially in terms of randomised trials remains limited. From a cost perspective, study conclusions are still conflicting and centres are recommended to perform their own micro cost analyses.Most clinical outcomes for single use ureteroscopes currently match those achieved by reusable ureteroscopes but the data pool is still limited. Areas of continued debate include their environmental impact and cost efficiency. All study types were eligible for inclusion. Bibliographic databases searched included PubMed/MEDLINE, Google scholar and Scopus. Reference lists and relevant grey literature such as conference abstracts were also searched. Search terms included ‘single use’, ‘disposable’, ‘ureteroscopy’, ‘retrograde intra‐renal surgery’ and ‘minimally invasive surgery’. The results have been summarised in a narrative format the following key areas identified: history and development, equipment specifications, equipment properties/findings from clinical studies, cost, environmental impact and future perspectives.3One of the earliest reports of flexible URS was by Marshall et al. in 1964 where an impacted ureteric calculus was visualised.4The lighting system is LED in the majority of the models with source integrated in the handle, but there are few exceptions such as Shaogang that has an external fibre optic cable attachment.4.1Within a short time period, numerous modifications have been introduced. Most models are now available with the option of the articulated lever executing either standard or reverse  deflection according to preference. Similarly, some models such as WiScope are available in left‐ and right‐handed versions. Certain models now have an autolock function that can be applied at the surgeon's discretion, for example, once deflected in lower pole. Such ergonomic improvements are welcomed given that 39% of endourologists have been reported to experience orthopaedic problems in their hand and/or wrist.Of note too, is the development of SU semi‐rigid ureteroscopes such as the RIWO D‐URS™ , which has a hybrid function in that the tip is flexible. It has an outer diameter of 9 Fr, and a special feature is that it houses three channels consisting of an outflow channel, a working channel (3.6 F) for accessories and a dedicated channel for the laser fibre (1.6 Fr). To date, formal studies are lacking, which report its use in a clinical setting.4.2Essential scope features include manoeuvrability, optical characteristics , working channel flow, deflection (including when working channel occupied) and durability . A number of in vitro simulation studies have been performed assessing these properties. Dragos et al. compared four different SU models with four of the main RU models in use.4.3n = 49) found that outcomes were comparable for all the same variables with the exception of SFR, which favoured the SU group . More recently, Ali et al. recorded results from a randomised study of 242 patients.To date, there have only been three randomised controlled trials (RCTs) comparing SU versus RU ureteroscopes. The first was a trial by Qi et al. in 126 patients.4.4p = 0.018).Reprocessing is a time intensive process that combines both manual and machine automated steps, and although protocols vary between sterile processing departments, drying alone can take over 3 h.4.5p < 0.05) less in the SU group.Expenditure associated with this technology is one of the main reasons for a slowed uptake across many parts of the world, especially those with less resources. Results of cost comparison studies reveal varying estimates.A new development has been the updated coding reimbursement for SU device has been adapted in certain areas such as the Medicare Hospital Outpatient Prospective Payment System (OPPS). Given it fulfils requirements for an innovative device, it qualifies for a transitional pass‐through payment, which equates to an additional reimbursement.4.62 footprint associated with transport of new endoscopes, those sent for repair and at the time of disposition. Factory locations for manufacture and repair are often located in another country.The healthcare sector currently accounts for 4.4% of global greenhouse gas emissions.Borofsky et al. reported their multi‐institutional pilot experience in the United States of a partnership with a medical waste company  that aimed to salvage metal and electronic components while electricity was generated from steam energy generated during incineration of medical waste.5Although reported repair rates vary, it is known that surgeon experience and investment in the education of operational staff can affect longevity of RU ureteroscopes.Endoscopic combined intra‐renal surgery (ECIRS) is also argued as a scenario to consider SU models. However, a recent study found that use of accessories such as baskets rendered more damage to ureteroscopes than performing ECIRS.6Other SU endoscopes used in medical setting have seen high growth rates in recent years. Sales for SU bronchoscopes and rhinoscopes have increased at 124% and 441% per year.7SU ureteroscopes have favourable physical characteristics including modifications and low weight that translate to certain ergonomic advantages for the surgeon. Clinical outcomes match those of RU models. However, both the economic and environmental sustainability warrant further research. Further studies are also needed to evaluate if SU models result in lower infection rates and to determine durability and issue of device failure intra‐operatively.Patrick Juliebø‐Jones: Conception; data collection; analysis; writing of draft and revision. Eugenio Ventimiglia: Conception; data collection; editing and writing of manuscript. Bhaskar K. Somani: Data collection; editing and writing of manuscript; supervision. Mathias Sørstrand Æsøy: Data collection; editing and writing of manuscript. Peder Gjengstø: Data collection; editing and writing of manuscript. Christian Beisland: Conception; data collection; editing and writing of manuscript; supervision. Øyvind Ulvik: Conception; data collection; editing and writing of manuscript; supervision.Øyvind Ulvik has acted as a consultant for Olympus. The other authors have nil to declare.