bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of clinical failure of anti-tau and anti-synuclein antibodies in neurodegeneration using a quantitative systems pharmacology model
Authors: Geerts Hugo , Bergeler Silke , Walker Mike , van der Graaf Piet H. , Courade Jean-Philippe
Published: September 2023

Misfolded proteins in Alzheimer’s disease and Parkinson’s disease follow a well-defined connectomics-based spatial progression. Several anti-tau and anti-alpha synuclein (aSyn) antibodies have failed to provide clinical benefit in clinical trials despite substantial target engagement in the experimentally accessible cerebrospinal fluid (CSF). The proposed mechanism of action is reducing neuronal uptake of oligomeric protein from the synaptic cleft. We built a quantitative systems pharmacology (QSP) model to quantitatively simulate intrasynaptic secretion, diffusion and antibody capture in the synaptic cleft, postsynaptic membrane binding and internalization of monomeric and oligomeric tau and aSyn proteins. Integration with a physiologically based pharmacokinetic (PBPK) model allowed us to simulate clinical trials of anti-tau antibodies gosuranemab, tilavonemab, semorinemab, and anti-aSyn antibodies cinpanemab and prasineuzumab. Maximal target engagement for monomeric tau was simulated as 45% (semorinemab) to 99% (gosuranemab) in CSF, 30% to 99% in ISF but only 1% to 3% in the synaptic cleft, leading to a reduction of less than 1% in uptake of oligomeric tau. Simulations for prasineuzumab and cinpanemab suggest target engagement of free monomeric aSyn of only 6–8% in CSF, 4–6% and 1–2% in the ISF and synaptic cleft, while maximal target engagement of aggregated aSyn was predicted to reach 99% and 80% in the synaptic cleft with similar effects on neuronal uptake. The study generates optimal values of selectivity, sensitivity and PK profiles for antibodies. The study identifies a gradient of decreasing target engagement from CSF to the synaptic cleft as a key driver of efficacy, quantitatively identifies various improvements for drug design and emphasizes the need for QSP modelling to support the development of tau and aSyn antibodies.
Comproportionation and disproportionation in nickel and copper complexes
Authors: Day Craig S. , Martin Ruben
Published: September 2023

This review covers factors that contribute to comproportionation and disproportionation reactions in transition metal complexes and provide insight into the importance of these electron transfer events in Ni- and Cu-catalyzed transformations.
Control of functionalized single-walled carbon nanotube photoluminescence via competition between thermal rearrangement and elimination
Authors: Maeda Yutaka , Morooka Rina , Zhao Pei , Yamada Michio , Ehara Masahiro
Published: September 2023

We conducted the chiral separation of functionalized single-walled carbon nanotubes (SWNTs) with dibromopropane derivatives.
Introducing an orthogonally polarized electron-rich alkene: synthesis of a zwitterionic boron-containing π-conjugated system
Authors: Chrysochos Nicolas , Pätsch Sebastian , Elvers Benedict J. , Krummenacher Ivo , Nandeshwar Muneshwar , Prabusankar Ganesan , Braunschweig Holger , Schulzke Carola , Ravat Prince , Jana Anukul
Published: September 2023

Here we are introducing an orthogonally polarized electron-rich alkene. Subsequently, we utilized this unique alkene motif for the synthesis of zwitterionic boron-containing π-conjugated compound.
Theoretical study of Mo2N supported transition metal single-atom catalyst for OER/ORR bifunctional electrocatalysis
Authors: Lin Long , Long Xiaoqin , Yang Xinyu , Shi Pei , Su Linlin
Published: September 2023

Rational design and development of efficient bifunctional catalysts for ORR and OER based on Mo2N materials provide a new idea for developing new renewable energy storage and conversion technologies.
The impact of Hubbard and van der Waals corrections on the DFT calculation of epsilon–zeta transition pressure in solid oxygen
Authors: Anh Le The
Published: September 2023

The short-range and long-range interactions calculated by using the DFT in solid oxygen are corrected by the Hubbard U and van der Waals corrections, respectively.
The electrophilic aromatic bromination of benzenes: mechanistic and regioselective insights from density functional theory
Authors: Deraet Xavier , Desmedt Eline , Van Lommel Ruben , Van Speybroeck Veronique , De Proft Frank
Published: September 2023

Insight into the energetics of competing reaction pathways for the electrophilic aromatic bromination on benzenes and the factors driving the regioselectivity of these mechanisms was provided based on a combination of conceptual tools.
Highly stable lanthanide(iii) metal–organic frameworks as ratiometric fluorescence sensors for vitamin B6
Authors: Wang Xiao-Qing , Yang Jiandong , Zhang Man , Wu Dan , Hu Tuoping , Yang Jie
Published: September 2023

Three lanthanide(III)-based metal-organic frameworks were built with a rigid tetracarboxylate organic ligand, which exhibit excellent sensing ability for vitamin B6 as the ratiometric fluorescence sensors.
Atmospheric oxidation impact on sea spray produced ice nucleating particles
Authors: DeMott Paul J. , Hill Thomas C. J. , Moore Kathryn A. , Perkins Russell J. , Mael Liora E. , Busse Heidi L. , Lee Hansol , Kaluarachchi Chathuri P. , Mayer Kathryn J. , Sauer Jonathan S. , Mitts Brock A. , Tivanski Alexei V. , Grassian Vicki H. , Cappa Christopher D. , Bertram Timothy H. , Prather Kimberly A.
Published: September 2023

Ice nucleating particles (INPs) in sea spray aerosol (SSA) are important for ice formation in clouds over oceans. We found that SSA INP concentrations during a phytoplankton bloom were degraded with exposure to 3 to 8 days of atmospheric oxidation.
Ni5Fe5/Al2O3 catalytic hydrogenolysis of lignin: mechanism investigation and selectivity regulation
Authors: Shen Zhensheng , Wang Wei , Pan Lun , Huang Zhenfeng , Zhang Xiangwen , Shi Chengxiang , Zou Ji-Jun
Published: September 2023

The development of novel catalysts to regulate product selectivity and insight into the mechanism of lignin hydrogenolysis are important for the comprehensive utilization of lignocellulose.
Ultrathin SU-8 membrane for highly efficient tunable cell patterning and massively parallel large biomolecular delivery
Authors: Shinde Pallavi , Shinde Ashwini , Kar Srabani , Illath Kavitha , Nagai Moeto , Tseng Fan-Gang , Santra Tuhin Subhra
Published: September 2023

Massively parallel high throughput single-cell intracellular delivery using infrared light pulses activated titanium micro-ring (TMR) device.
Reflow-molded deep concave microwell arrays for robust and large-scale production of embryoid bodies
Authors: Han Xue , Zhang Qi , He Hui , Zhao Qiang , Li Gang
Published: September 2023

An extremely simple, feasible, and economical method for preparing high-quality and deep concave microwell arrays is presented for robustly producing homogeneous EBs on a large scale.
Solid-phase synthesis of oligodeoxynucleotides using nucleobase N-unprotected oxazaphospholidine derivatives bearing a long alkyl chain
Authors: Kakuta Kiyoshi , Kasahara Ryouta , Sato Kazuki , Wada Takeshi
Published: September 2023

This report describes a method for the synthesis of oligonucleotides without nucleobase protection using oxazaphospholidine monomers which have a long alkyl chain.
The use of frameworks in chemistry education research
Authors: Rodriguez Jon-Marc G. , Nardo Jocelyn Elizabeth , Finkenstaedt-Quinn Solaire A. , Watts Field M.
Published: September 2023

Extant literature has emphasized the importance of education research being theory-based. To this end, many research articles have a distinct “theoretical framework” section describing the theoretical underpinnings that inform the research. Nevertheless, there is large variation in how explicit articles are regarding their use of frameworks in the research process. This work describes a literature review focusing on the use of frameworks (broadly defined) in chemistry education research. Our sample draws on research articles published in Chemistry Education Research and Practice and the Journal of Chemical Education from 2018 to 2021 (n = 457). The longitudinal analysis revealed general trends about the presence of frameworks in research articles over four years as well as the types of frameworks commonly used. In addition, we analyzed how frameworks were used within individual research articles published in 2021, focusing on chemistry education research articles and research articles published across biology, engineering, mathematics, and physics education research journals (n = 595). Our goal is to describe how frameworks were used to open a dialogue and inform future chemistry education research.
A New Left Atrial Catheter
Authors: Athanasuleas C.L. , McFalls Richard
Published: September 2023

A new catheter was designed which permits easy insertion of a polyurethane catheter into the left atrium utilizing a “breakaway” needle system. The advantages of such a system include a needle size hole into the pulmonary vein and the security of a luer lock connector at the distal catheter end.
The pO2 of Samples Drawn from the Shiley S-100A Arterial Reservoir Is Not an Accurate Indicator of Arterial Line pO2
Authors: Wagoner Philip A. , Pauley David W. , Brown Darrell M. , Plevich Joel P.
Published: September 2023

While conducting clinical bypass with the Shiley S-100A bubble oxygenator, an observation was made that arterial pO2 values reported by the laboratory were routinely inconsistent with inline arterial blood oxygen saturation measurements. It was also noted that the blood in the arterial reservoir in the vicinity of the arterial sampling port was often darker in color than the blood in the arterial line.

Sixty-four simultaneously drawn pairs of arterial blood gas samples were drawn from the arterial reservoir sampling port and from the purge line of the arterial line filter (ALF). In all instances, the pO2 of the sample drawn from the arterial line filter exceeded the pO2 of the corresponding sample drawn from the arterial reservoir. The percentage difference between the pO2 of samples drawn from the ALF and from the arterial reservoir correlated strongly (p < .01) with the arterial blood temperature and moderately (p < 0.2) with the reservoir level. No significant differences were found between the pCO2, pH and base excess of the ALF and the arterial reservoir.

The authors postulate that the discrepancy in pO2 between the arterial reservoir sampling port and the ALF is a result of rapid channelling of partially oxygenated blood through the defoamer into the vicinity of the arterial sampling port. The rapidly channelled blood is, therefore, deprived of the additional oxygenation that occurs in the defoamers of bubble oxygenators.

It is recommended that Shiley reposition the S-100A’s arterial sampling port closer to, the arterial reservoir outlet port and that a unidirectional valve be inserted to prevent inadvertent introduction of air to the arterial reservoir. Until this design modification is carried out, the authors recommend that clinical users of the S-100A draw arterial blood gas samples directly from the arterial line or from the ALF purge line.
A Reliable Method for Determination of Initial Sweep Gas Flow Rates Using the CML Oxygenator
Authors: Myers Gerard J.
Published: September 2023

(J. Extra-Corpor. Technol. 18[4] p.221–224 Winter 1986) The Cobe Membrane Lung Oxygenator is a Z folded flat plate membrane made of polypropylene material, with an effective surface area of 2.5m2. Since its introduction to the market in 1982, it has provided perfusionists with all the benefits of the membrane technology, while utilizing an ease of operation that is equal to the bubble oxygenator. Cobe’s initial recommendation for use was to maintain a constant sweep gas flow rate of 10 liters/minute and control the pCO2 by adding extraneous carbon dioxide to this ventilating gas. However, the use of Alpha Stat Control (nontemperature correction) for acid base balance requires the elimination of all extraneous carbon dioxide during bypass, and thereby has required perfusionists to rely on their own experience with this membrane, or follow Cobe’s second recommendation of establishing an initial sweep gas flow rate of 1:1 (gas:blood).

Presented here is a method of determining the initial sweep gas flow rate while using Alpha Stat Control. This method appears useful during the initiation of bypass and the use of moderate hypothermic temperature. A well-known parameter in respiratory medicine, the V/Q ratio, is used in the determination and must be established prior to bypass.

The results of this paper indicate that use of the V/Q ratio in establishing a desired PaCO2 for the first 1 0 minutes of bypass is more reliable and consistent than the use of the 1:1 gas to blood flow ratio. However, the method has proved useful only for the initial blood gas sampling, after which sweep gas flows must be reduced to a V/Q of at least 1.0 for the remainder of the case. Use of the V/Q ratio appears to allow the perfusionist to predict the initial PaCO2 within an accuracy of ± 4 mmHg.
The Development of a Perfusion Educational Program
Authors: Paules Brian R.
Published: September 2023

(J. fxtra-Corpor. Technol. 19[2] p. 216–220 Summer 1987). The development of a School of Perfusion Technology starts with a purpose statement that defines the need for such a program and the role of the school within the professional community.

After defining the purpose for such an educational program, a task analysis provides the program description of a perfusionist, which later is used to develop the curriculum. A goal analysis details what the student and program will achieve at completion. A statement of the professional and educational philosophy along with the program objective complete the basic foundation.

Level of sponsorship of the program determines the duration of education, physical resources, budgetary support, clinical availability and instructional faculty. A target population study forms the basis to define the applicant traits desirable for the program. All of the above data are combined to generate an application process and to begin to create the curriculum.

Specific subject matter is listed to include all pertinent and ancillary topics along with the approximate time required to cover each topic. Classes are developed from the topic list, with material coordinated to provide an overlap of knowledge between classes. Statement of course goals and objectives defines the learning expectation while the examination evaluates student knowledge.

Clinical rotations provide the opportunity for practical application of the scientific principles learned in the didactic portion of the education. Pre and post clinical evaluations are essential toward determining student’s strengths and weaknesses, in order to validate his or her knowledge in the clinical practice. This form of education mandates a single instructor per student and continual vigilance.

An outcome analysis is generated after graduation with employer feedback and peer review of the graduate perfusionist. From this analysis the program goals and objectives are tested, and program re-evaluation begins.
Preservation of Canine Platelets with Iloprost (ZK 36374) during Extracorporeal Circulation
Authors: Stenach Nina , Cottrell Earl D. , Fisher Carol A. , Kappa Jeffrey R. , Addonizio V. Paul
Published: September 2023

(J. Extra-Corpor. Technol. 19[3] p. 258-264 Fall 1987, 23 ref.) Contact between blood and synthetic/air interfaces during extracorporeal circulation (ECC) results in adverse platelet alterations. We tested the efficacy of a new reversible potent prostacyclin analogue, iloprost (ZK 36374), in preventing these untoward conseguences in fifteen mongrel dogs undergoing extracorporeal circulation using either a membrane or bubble oxygenator. In treated groups, infusion of iloprost was incrementally increased to 150 ng/kg/min at least 15 minutes prior to incision. Equal infusion volumes of saline were administered to the control group. Platelet counts in control dogs (n = 6, membrane/control) decreased to 57 ± 10% (mean ± standard error of the mean) of initial levels by 30 minutes of ECC; in contrast, dogs infused with iloprost demonstrated consistently stable platelet counts despite perfusion with either membrane (1 07 ± 1 0%, n = 6) or bubble (81 ± 13%, n = 3) oxygenators. At 30 minutes of ECC, the iloprost infusion was discontinued. Although the platelet counts in the membrane iloprost-treated group continued to remain stable (99 ± 7%), platelet counts in the bubble iloprost-treated group droppped precipitously to 49 ± 1 0% within 60 minutesof discontinuance of infusion. Furthermore, by 90 minutes of ECC, platelets continued to demonstrate reduced sensitivity to ADP as measured by percent light transmission in both control (53 ± 15%) and bubble iloprost-treated (20 ± 16%) groups. In contrast, the membrane iloprost-treated group regained normal reactivity (80 ± 15%). We conclude that iloprost effectively prevents adverse platelet alterations during ECC. Furthermore, its salutary effects in membrane oxygenator systems persist long after platelet functional inhibition is reversed.
Hematological Effects during Clinical Extracorporeal Circulation: A 200 Case Study of the Shiley M-2000 Membrane System
Authors: John E. Briddon D.
Published: September 2023

(J. Extra-Corpor. Technol. 19[3] p. 312-315 Fall 1987, 6 ref.) The hematological effects of the Shiley M-2000 Membrane Oxygenator System were evaluated during and after cardiopulmonary bypass (CPB) in 200 patients who required coronary artery revascularization. A strict protocol for perfusion management and blood sampling was established and adhered to. Bypass times varied from 11/2 hours to 81\2 hours (X = 2 hrs 48 mins). Hemolysis was observed to be minimal, blood cells were well preserved, and, in particular, platelet counts and platelet function remained stable, even in bypass times in excess of 8 hours.

It was noted that when CPB was discontinued, and protamine sulphate infusion commenced, platelet function decreased slightly, although the platelet counts remained unchanged. Average postoperative blood loss was 390 mls (21 0 mls-1 ,400 mls range), statistically significantly lower than the average blood loss in a previous study at our center, which utilized the same protocol but an alternative membrane (Cobe CML).

In summary the Shiley M-2000 Membrane is a safe and extremely hemocompatible system for use in short- to medium-term perfusions.
In Vitro Measurement of the Accuracy of a New Patient Side Blood Gas, pH, Hematocrit and Electrolyte Monitor
Authors: Riley Jeffrey B. , Burgess Bruce M. , Smith Christine A. , Crowley Jeffrey C. , Soronen Scott W.
Published: September 2023

(J. Extra-Corpor. Technol. 19[3] p. 322-329 Fall 1987, 34 ref.) An In Vitro human blood circuit was brought to equilibrium with five analyzed gases and at varied electrolyte concentrations to determine the accuracy of the GEM-6 analyzer with respect to current market standard analyzers.

Diamond Sensor Systems GEM-6
Radiometer A/S ABL-4 Blood Gas and pH Analyzer
Nova Stat Electrolyte Monitor
Becton Dickman Readacrit Centrifuge

Correlation Coefficient (r)

pH
0.9988
—
—

pCO2
0.99864
—
—

pO2
0.9933
—
—

Hct%
—
—
0.79205

K+
0.99695
0.99553
—

Ca++
—
0.98399
—

[HCO3-]
0.9738
—
—

B.E.
0.8022
—
—

%Hb·O2
0.9546
—
—

(n = 60, all r values are significant at p<.001)

The GEM-6 is equivalent to current analyzers that measure the same parameters.
Micro-Prime Circuit Facilitating Minimal Blood Use during Infant Perfusion
Authors: Tyndal Charles M. , Berryessa Richard G. , Campbell David N. , Clarke David R.
Published: September 2023

(J. Extra-Corpor. Technol. 19[3] p. 352-357 Fall 1987, 24 ref.) There is considerable concern about the use of blood products during cardiac surgery on the part of adult patients and the parents of pediatric patients. It has been fairly easy to eliminate blood usage in most adult patients but difficult to impossible in infants and small children. Most infant perfusion circuits require a priming volume of 500-850cc which may be cut to 400cc with substantial effort. These volumes are far in excess of the blood volume of most newborns requiring cardiac surgery. We have developed and refined a circuit using commonly available components that can be primed with as little as 265cc. The circuit consists of a Capiox II 0.8m2 lung, with a Terumo 1 OOcc venous reservoir bag and 1/4″ lines. It incorporates a level sensor, bubble detector, recirculation line, arterial GasSTAT™ sensor, and sampling and pressure monitoring lines. A priming volume this low facilitates minimal blood usage in even the smallest infants. This circuit is especially applicable for use with children of Jehovah's Witness parents. It is unique from a safety standpoint in that it not only allows level sensing and bubble detection, but the lung is inverted so the inlet is at the top and the outlet is at the bottom. This configuration causes the lung to act as a bubble trap which may decrease gaseous microemboli. We will describe this “microprime” circuit allowing minimal or no blood usage in this age group, including a review of the literature concerning the safe limits of hemodilution.
Transient Hypoglycemia and Biochemical Differences in Infants Less Than 1,250 G at Birth Fed Human Milk with Human Milk–Derived Fortifier versus Cow Milk–Derived Fortifier
Authors: Chang Millie R. , Tetarbe Manas , Barton Lorayne , Ramanathan Rangasamy , Cayabyab Rowena
Published: September 2023

Objective Fortification of human milk (HM) with either human milk-derived fortifier (HMDF) or cow milk-derived fortifier (CMDF) is important in preterm infants. The objective is to compare the incidence of hypoglycemia, and biochemical values in infants less than 1,250 g at birth fed HMDF versus CMDF.

Study Design It is a retrospective cohort study on infants less than 1,250 g at birth who were fed with HMDF or CMDF. Hypoglycemia was defined as blood glucose (BG) level equal to or less than 60 mg/dL within 72 hours of full enteral feeds when off total parenteral nutrition and intravenous fluids.

Results Ninety infants were enrolled (HMDF = 61, CMDF = 29). HMDF group had a higher rate of hypoglycemia (46 vs. 24%; p = 0.048) after achievement of full enteral feeding. The median minimum BG was lower (61 vs. 71; p ≤ 0.01), while blood urea nitrogen (12 vs. 6; p ≤ 0.01) and albumin (3.1 vs. 2.7; p ≤ 0.01) were higher in HMDF group compared with CMDF.

Conclusion At full enteral feedings in infants less than 1,250 g at birth, an HMDF diet may predispose to hypoglycemia needing intervention. Close monitoring of BG levels once off parenteral nutrition is recommended.

Key Points
Phenotypes of Disseminated Intravascular Coagulation
Authors: Wada Takeshi , Gando Satoshi
Published: September 2023

Two phenotypes of disseminated intravascular coagulation (DIC) are systematically reviewed. DIC is classified into thrombotic and fibrinolytic phenotypes characterized by thrombosis and hemorrhage, respectively. Major pathology of DIC with thrombotic phenotype is the activation of coagulation, insufficient anticoagulation with endothelial injury, and plasminogen activator inhibitor-1-mediated inhibition of fibrinolysis, leading to microvascular fibrin thrombosis and organ dysfunction. DIC with fibrinolytic phenotype is defined as massive thrombin generation commonly observed in any type of DIC, combined with systemic pathologic hyperfibrinogenolysis caused by underlying disorder that results in severe bleeding due to excessive plasmin formation. Three major pathomechanisms of systemic hyperfibrinogenolysis have been considered: (1) acceleration of tissue-type plasminogen activator (t-PA) release from hypoxic endothelial cells and t-PA-rich storage pools, (2) enhancement of the conversion of plasminogen to plasmin due to specific proteins and receptors that are expressed on cancer cells and endothelial cells, and (3) alternative pathways of fibrinolysis. DIC with fibrinolytic phenotype can be diagnosed by DIC diagnosis followed by the recognition of systemic pathologic hyperfibrin(ogen)olysis. Low fibrinogen levels, high fibrinogen and fibrin degradation products (FDPs), and the FDP/D-dimer ratio are important for the diagnosis of systemic pathologic hyperfibrin(ogen)olysis. Currently, evidence-based treatment strategies for DIC with fibrinolytic phenotypes are lacking. Tranexamic acid appears to be one of the few methods to be effective in the treatment of systemic pathologic hyperfibrin(ogen)olysis. International cooperation for the elucidation of pathomechanisms, establishment of diagnostic criteria, and treatment strategies for DIC with fibrinolytic phenotype are urgent issues in the field of thrombosis and hemostasis.
Multilayering FeGa with NiFe and Al2O3 to enhance the soft magnetic properties
Authors: Acosta Adrian , Burnside Emily , Fitzell Kevin , Carman Gregory P. , Chang Jane P.
Published: September 2023

In this study, the impact of insulating Al2O3 interlayers on the static and dynamic magnetic properties of FeGa/NiFe multilayers was investigated. A multilayer structure consisting of ten (10 nm FeGa)/(2.5 nm NiFe) bilayers was first established to show a reduction in coercivity and high frequency losses compared to a single (100 nm FeGa)/(2.5 nm NiFe) bilayer, which itself shows better performance than a single 100 nm FeGa film. By strategically placing 2.5 nm Al2O3 interlayers in the FeGa/NiFe multilayers (after the FeGa layer but before the next NiFe layer), the composite displayed a reduced coercivity down to 3 Oe while retaining a strong uniaxial anisotropy. Due to the effectiveness of these ultra-thin Al2O3 layers in reducing the eddy current losses across the FeGa/NiFe multilayer stack, this multilayer structure exhibited excellent performance at high frequency, including a gilbert damping coefficient of 0.0081 and an inhomogeneous linewidth of 38 Oe. These results demonstrate that Al2O3 interlayers can improve the soft magnetic properties of (FeGa/NiFe)-based multilayers to enable integration in magnetoelastic and high frequency applications.
Photoacoustic study of elastic deformations in silicon membranes
Authors: Todorovic D. M.
Published: September 2023

In an optically excited semiconductor micromechanical structure, photogenerated carriers (plasma waves) can produce elastic deformations (local strains and stresses)–plasmaelastic (PE) deformations. On the other hand, the generation of excess carriers will produce heat due to carrier thermalization and recombination processes. The generated heat can produce other elastic deformations–thermoelastic (TE) deformations. For these two components of elastic deformation, it is possible to consider two types of elastic displacements (two mods of elastic vibrations): elastic expanding and elastic bending. A theoretical model of the photoacoustic (PA) signal for optically excited Si membranes is given, which includes thermal diffusion (TD), TE, and PE mechanisms, in order to study elastic expansion and bending. The relations for the PA amplitude and the phase of elastic expanding and bending in the excited membrane are derived. Analysis of the PA signal indicates that the TD component is dominant for all thicknesses and practically the entire range of observed frequencies. The calculated PA amplitude and phase spectra show that the PA elastic expanding component has a significant influence on the total PA signal at low frequencies. On the other side, the calculated PA spectra show that the PA elastic bending component has a significant influence on the total PA signal at high frequencies. Experimental PA signals of Si membranes were measured using the sample-gas-microphone detection technique with a transmission configuration in relation to the modulation frequency of the optical excitation for different membrane thicknesses. The experimental PA spectra were compared with the theoretical ones.
Continuity of attractors for singularly perturbed semilinear problems with nonlinear boundary conditions and large diffusion
Authors: Pires L. , Samprogna R. A.
Published: September 2023

We exhibit singularly perturbed parabolic problems with large diffusion and nonhomogeneous boundary conditions for which the asymptotic behavior can be described by a one-dimensional ordinary differential equation. We estimate the continuity of attractors in Hausdorff’s metric by the rate of convergence of resolvent operators. Moreover, we will show explicitly how this estimate of continuity varies exponentially with the fractional power spaces Xα for α in an appropriate interval.
Quasiperiodicity in the
α
-Fermi–Pasta–Ulam–Tsingou problem revisited: An approach using ideas from wave turbulence
Authors: Ganapa Santhosh
Published: September 2023

The Fermi–Pasta–Ulam–Tsingou (FPUT) problem addresses fundamental questions in statistical physics, and attempts to understand the origin of recurrences in the system have led to many great advances in nonlinear dynamics and mathematical physics. In this work, we revisit the problem and study quasiperiodic recurrences in the weakly nonlinear α-FPUT system in more detail. We aim to reconstruct the quasiperiodic behavior observed in the original paper from the canonical transformation used to remove the three-wave interactions, which is necessary before applying the wave turbulence formalism. We expect the construction to match the observed quasiperiodicity if we are in the weakly nonlinear regime. Surprisingly, in our work, we find that this is not always the case and in particular, the recurrences observed in the original paper cannot be constructed by our method. We attribute this disagreement to the presence of small denominators in the canonical transformation used to remove the three-wave interactions before arriving at the starting point of wave turbulence. We also show that these small denominators are present even in the weakly nonlinear regime, and they become more significant as the system size is increased. We also discuss our results in the context of the problem of equilibration in the α-FPUT system and point out some mathematical challenges when the wave turbulence formalism is applied to explain thermalization in the α-FPUT problem. We argue that certain aspects of the α-FPUT system such as thermalization in the thermodynamic limit and the cause of quasiperiodicity are not clear, and that they require further mathematical and numerical studies.
Study of trigger mechanisms of a pseudospark switch configuration with a steady-state auxiliary glow discharge
Authors: Korolev Y. D. , Landl N. V. , Frants O. B. , Geyman V. G. , Bolotov A. V. , Nekhoroshev V. O.
Published: September 2023

This paper presents data on investigation of the pseudospark switch whose trigger unit uses a low-current auxiliary glow discharge with hollow cathode and hollow anode. The electrode system of this unit communicates with the main high-voltage gap of the switch due to the aperture in the flat part of one of the trigger electrodes. It is shown that when the electrode with the aperture plays of role of the hollow cathode of the auxiliary discharge, a low parasitic current through the aperture is provided by the ion flow. This ion current does not practically influence on the static breakdown voltage of the main gap. Applying the trigger pulse between the trigger electrodes leads to the pulsed trigger discharge with an enhanced current. At a negative polarity of the trigger pulse, the cavity with aperture turns out into the hollow anode so that the current is able to be intercepted through the aperture to the grounded cavity of the main gap. The plasma is generated in the cavity and the switch is triggered. With the proper selection of the geometry of the trigger electrodes, the delay time to trigger at a level of several tens of nanoseconds is achievable.
Hot spots of the main limiter induced by fast ions in experimental advanced superconducting tokamak (EAST)
Authors: Li Y. L. , Xu Y. F. , Xu X. Y. , Xu G. S. , Liang R. R. , Ding R. , Liu X. , Geng K. N. , Zhang T. , Wang S. X. , Fan H. C. , Zhong G. Q. , Fu S. Y. , Lu D. A. , Mao S. T. , Fu J. , Zang Q. , Cao L. , Zhang B. , Wang L. , Chen R. , Yan N. , Yang Q. Q. , Liu H. Q. , Xie Y. L. , Gong X. Z. , Hu J. S. ,   EAST team
Published: September 2023

The main limiter in EAST was observed to endure a high heat load and was cracked near the midplane at the right side during the plasma operation. To explore the heat load carried by fast ion loss toward the main limiter, the neutral beam injection (NBI) and radio frequency power proportion experiment was conducted in EAST where the plasma stored energy and line integrated density were kept almost constant. The hot spot at the right side of the main limiter was observed to be enhanced by co-current perpendicular (co-perp) NBI. An NBI ion loss simulation was performed in the presence of the toroidal field ripple and the Coulomb collision by using the orbit code GYCAVA and the NBI code TGCO. The result indicates that the NBI ion loss by ripple and collision mainly causes a bright area below the midplane of the right side of the main limiter as observed in the EAST experiment. The peak heat load of lost fast ions generated by co-perp NBI is ∼0.5 MW/m2 as obtained by 1 MW of NBI deposited power and comparable with the heat load carried by fast electrons induced by lower hybrid current drive. In addition, increasing the gap between the separatrix and the first-wall limiters in the simulation is found to reduce this heat load.
GraphVAMPnets for uncovering slow collective variables of self-assembly dynamics
Authors: Liu Bojun , Xue Mingyi , Qiu Yunrui , Konovalov Kirill A. , O’Connor Michael S. , Huang Xuhui
Published: September 2023

Uncovering slow collective variables (CVs) of self-assembly dynamics is important to elucidate its numerous kinetic assembly pathways and drive the design of novel structures for advanced materials through the bottom-up approach. However, identifying the CVs for self-assembly presents several challenges. First, self-assembly systems often consist of identical monomers, and the feature representations should be invariant to permutations and rotational symmetries. Physical coordinates, such as aggregate size, lack high-resolution detail, while common geometric coordinates like pairwise distances are hindered by the permutation and rotational symmetry challenges. Second, self-assembly is usually a downhill process, and the trajectories often suffer from insufficient sampling of backward transitions that correspond to the dissociation of self-assembled structures. Popular dimensionality reduction methods, such as time-structure independent component analysis, impose detailed balance constraints, potentially obscuring the true dynamics of self-assembly. In this work, we employ GraphVAMPnets, which combines graph neural networks with a variational approach for Markovian process (VAMP) theory to identify the slow CVs of the self-assembly processes. First, GraphVAMPnets bears the advantages of graph neural networks, in which the graph embeddings can represent self-assembly structures in high-resolution while being invariant to permutations and rotational symmetries. Second, it is built upon VAMP theory, which studies Markov processes without forcing detailed balance constraints, which addresses the out-of-equilibrium challenge in the self-assembly process. We demonstrate GraphVAMPnets for identifying slow CVs of self-assembly kinetics in two systems: the aggregation of two hydrophobic molecules and the self-assembly of patchy particles. We expect that our GraphVAMPnets can be widely applied to molecular self-assembly.
Shock state distributions in porous tantalum and characterization with multipoint velocimetry
Authors: Moore Nathan W. , Carleton James B. , Wise Jack L. , McCoy Chad A. , Vackel Andrew , Bolintineanu Dan S. , Kaufman Morris , Kracum Michael R. , Battaile Corbett C. , Rodgers Theron M. , Sanchez Jason J. , Mesh Mikhail , Olson Aaron J. , Scherzinger William M. , Powell Michael J. , Payne Sheri L. , Pokharel Reeju , Brown Donald W. , Frayer Daniel K.
Published: September 2023

Heterogenous materials under shock compression can be expected to reach different shock states throughout the material according to local differences in microstructure and the history of wave propagation. Here, a compact, multiple-beam focusing optic assembly is used with high-speed velocimetry to interrogate the shock response of porous tantalum films prepared through thermal-spray deposition. The distribution of particle velocities across a shocked interface is compared to results obtained using a set of defocused interferometric beams that sampled the shock response over larger areas. The two methods produced velocity distributions along the shock plateau with the same mean, while a larger variance was measured with narrower beams. The finding was replicated using three-dimensional, mesoscopically resolved hydrodynamics simulations of solid tantalum with a pore structure mimicking statistical attributes of the material and accounting for radial divergence of the beams, with agreement across several impact velocities. Accounting for pore morphology in the simulations was found to be necessary for replicating the rise time of the shock plateau. The validated simulations were then used to show that while the average velocity along the shock plateau could be determined accurately with only a few interferometric beams, accurately determining the width of the velocity distribution, which here was approximately Gaussian, required a beam dimension much smaller than the spatial correlation lengthscale of the velocity field, here by a factor of ∼30×, with implications for the study of other porous materials.
Influence of distributed hydrogen injection and combustion on supersonic boundary layer stability and transition
Authors: Lysenko V. I. , Gaponov S. A. , Smorodsky B. V. , Semenov A. N. , Morozov S. O. , Starov A. V.
Published: September 2023

This theoretical study recorded the influence of the distributed injection of hydrogen through a permeable surface and its combustion on the stability and transition of a supersonic boundary layer (BL). The laminar base flow for a multicomponent flat-plate BL was computed using the computational fluid dynamics solver with finite-rate chemistry for free-stream Mach number (M) = 2. Linear stability theory (LST) equations for a reactive gas mixture were derived in the local parallel base flow approximation. Stability calculations based on the developed theory revealed the possibility of a decrease in the local spatial amplification rates of unstable perturbations. A double reversal in the maximal amplification rate magnitudes of perturbations was obtained, wherein at first, they increased, then decreased to zero, and then rose again. The influence of the distributed injection and combustion of hydrogen in the supersonic BL on the position of the laminar-turbulent transition was estimated using the LST-based eN-method. Calculated and experimentally obtained dependencies of the relative transition Reynolds number on the relative mass flow rate of injected hydrogen were compared. It was found that depending upon the flow conditions, the hydrogen diffusion flame could accelerate or decelerate the transition in the supersonic M = 2 BL, when compared to absence of hydrogen burning. Two counteracting effects compete: heat supply by combustion exerts stabilizing influence, while low-molecular-weight gas blowing from the surface exerts destabilizing influence. Depending on the interplay of these two factors, it would be possible to obtain acceleration or deceleration of transition.
Reversed Cherenkov radiation amplifier with compact structure and high efficiency
Authors: Wang Chuanchao , Li Xiaoyi , Lyu Zhifang , Zhang Xuanming , Jiang Shengkun , Wang Shaomeng , Wang Zhanliang , Gong Huarong , Gong Yubin , Duan Zhaoyun
Published: September 2023

Based on the reversed Cherenkov radiation excited in metamaterials, a novel S-band reversed Cherenkov radiation amplifier (RCRA) with two output ports is proposed in this paper. Its metamaterial slow-wave structure (MSWS) consists of a hollow circular waveguide periodically loaded with all-metal double-ridge complementary electric split-ring resonators (CeSRRs). The CeSRR exhibits subwavelength and strong resonance characteristics, which lead to miniaturization and high interaction impedance of the MSWS. The period of the MSWS is optimized using the phase velocity jump technique to further increase the output power and electronic efficiency. The simulation results demonstrate that when the microwave signal of 7.8 W at 2.286 GHz is inputted at port 2, the output power at port 1 is 307 W, and the saturated output power and saturated gain at port 3 are 5.48 kW and 28.47 dB, respectively. Notably, the total electronic efficiency of the RCRA is predicted as 33.84%. The RCRA features high electronic efficiency and miniaturization and may meet special application scenarios that require two output microwave signals at the same frequency.
Development of a cell for in-situ/operando Mössbauer spectroscopy studies of Catalysts: Application to the characterization of iron nanoparticles used in Fischer–Tropsch reaction
Authors: Huve J. , Bourgain F. , Farrusseng D. , Millet J. M. M.
Published: September 2023

In this paper, we report the design of a stainless-steel cell with polyimide film windows for carrying out in situ Mossbauer spectroscopy studies with a horizontal x-ray beam. It allows recording spectra at pressures up to 0.2–0.3 MPa and temperatures up to 500 °C under a gas flow rate of up to 100 ml min−1. The catalyst is either directly deposited on the heating element or pressed into the form of a pellet for larger quantities. A wide range of heating or cooling rates can be used, and a very accurate sample temperature can be monitored for several days. An example of application to the study of a catalyst based on iron nanoparticles entrapped in silicalite-1 used for the Fischer–Tropsch reaction is presented to illustrate the use of the cell.
Battery-free temperature logger for deep-sea hydrothermal fluids based on heat pipe heat exchangers and thermoelectric generators
Authors: Wu Shijun , Zheng Yunchao , Zhang Feng , Yang Canjun
Published: September 2023

Long-term in situ measurements of the temperature of hydrothermal fluids have great significance in the research of seafloor hydrothermal activities. Herein, we developed a self-powered battery-free temperature logger for measuring and recording the temperature of hydrothermal fluids. A gravity heat pipe made of titanium alloy was employed as the heat-conducting element of the temperature logger to capture heat from a hydrothermal vent and transfer it to the thermoelectric unit. The thermoelectric generator used herein converted the temperature difference into electrical energy to power the circuit of the temperature logger. Numerical analyses and experiments were performed to investigate the performance of the heat pipe and temperature logger. Results show that the temperature logger can realize self-powered starting at a temperature of >76 °C during a tank test. This paper presents a discussion on a new instrument for temperature measurements of deep-sea hydrothermal fluids.
Nonadiabatic dynamics near metal surfaces under Floquet engineering: Floquet electronic friction vs Floquet surface hopping
Authors: Wang Yu , Dou Wenjie
Published: September 2023

In the previous study Wang and Dou [J. Chem. Phys. 158, 224109 (2023)], we have derived a Floquet classical master equation (FCME) to treat nonadiabatic dynamics near metal surfaces under Floquet engineering. We have also proposed a trajectory surface hopping algorithm to solve the FCME. In this study, we map the FCME into a Floquet Fokker–Planck equation in the limit of fast Floquet driving and fast electron motion as compared to nuclear motion. The Fokker–Planck equation is then being solved using Langevin dynamics with explicit friction and random force from the nonadiabatic effects of hybridized electrons and Floquet states. We benchmark the Floquet electronic friction dynamics against Floquet quantum master equation and Floquet surface hopping. We find that Floquet driving results in a violation of the second fluctuation–dissipation theorem, which further gives rise to heating effects.
Excited states with pair coupled cluster doubles tailored coupled cluster theory
Authors: Ravi Moneesha , Perera Ajith , Park Young Choon , Bartlett Rodney J.
Published: September 2023

It is known that some non-dynamic effects of electron correlation can be included in coupled cluster theory using a tailoring technique that separates the effects of non-dynamic and dynamic correlations. Recently, the simple pCCD (pair coupled cluster doubles) wavefunction was shown to provide good results for some non-dynamic correlation problems, such as bond-breaking, in a spin-adapted way with no active space selection. In this paper, we report a study of excited states using “tailored coupled cluster singles and doubles,” to attempt to use pCCD as a kernel for more complete coupled-cluster singles and doubles (CCSD) results for excited states. Several excited states are explored from those primarily due to single excitations to those dominated by doubly excited states and from singlet–triplet splittings for some diradical states. For the first two situations, tailored pCCD-TCCSD offers no improvement over equation of motion-CCSD. However, when we explore the singlet–triplet gap of diradical molecules that are manifestly multi-reference, a pCCD kernel provides improved results, particularly with generalized valence bond orbitals.
Au-MoS2 contacts: Quantum transport simulations using a continuum description
Authors: Reyntjens Peter D. , Van de Put Maarten L. , Baikadi Pranay , Kim Raseong , Sorée Bart , Vandenberghe William G.
Published: September 2023

We present a novel method of modeling the contact between a metal and a two-dimensional semiconductor. Using Au on MoS2 as an example, we self-consistently solve the Schrödinger and Poisson equations and obtain the charge density in the contact. We consider open boundary conditions using the quantum transmitting boundary method and model the electron current through the contact region. We then investigate the effect of effective Schottky barrier height, electrostatic doping, and length of the overlap region on the contact resistance in a top contact geometry. By using data from experiments or from ab initio calculations for the fitting of parameters, such as the effective Schottky barrier height, the model can be used to efficiently obtain the contact resistance and, therefore, the quality of the contact. Furthermore, we investigate the effect of sampling of the Brillouin zone in the transverse direction on the numerical calculation of key quantities, such as contact resistance and free charge density. Additionally, we show that the boundary conditions applied to the Poisson equation during the calculation of the free charge density have a significant impact on the calculated contact resistance and that the impact is more pronounced in heterostructures with a larger Schottky barrier. We found that the contact resistance may be significantly underestimated, by up to one order of magnitude, when the height of the simulation domain is not large enough.