bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvement of sound barriers using headpieces with finite acoustic impedance
Authors: Möser Michael , Volz Rudi
Published: July 2002

The paper deals with the reduction of the sound energy in the shadow region behind barriers by means of an attached body at the edge of the screen. The reflecting attributes of the barrier’s headpiece are described by a locally reacting impedance. Diffraction at ideal soft and hard bodies demonstrates the basic principle of tangential power transport parallel to their surface: the impedance must be chosen so that the tangential intensity near the edge is lowered, turning the incoming power in harmless directions. The differences due to finite impedances are then discussed. The physical principles are demonstrated in frozen pictures of the sound field for the different cases. Theoretical computations show considerably improved levels in the shadow zone for larger angles of diffraction. These are compared with empirical results, and practical applications are discussed.
Ultrasound field estimation method using a secondary source-array numerically constructed from a limited number of pressure measurements
Authors: Fan Xiaobing , Moros Eduardo G. , Straube William L.
Published: July 2002

A new and faster method for the accurate estimation of acoustic fields of underwater ultrasonic transducers was developed, tested experimentally, and compared to previously reported methods. Using a limited number of pressure measurements close to the transducer’s face, the method numerically constructs a virtual secondary source-array whose acoustic field is similar to the field generated by the actual transducer (primary source). The measured data are used to obtain the normal particle velocity on the surface of the virtual secondary source-array, which in turn permits the calculation of the forward propagating field using the Rayleigh–Sommerfeld diffraction integral. The method is novel in that it constructs a virtual secondary source-array, thus eliminating the problems associated with obtaining the excitation source of a real transducer; and it is faster because it uses finite differences instead of a matrix inversion to obtain the excitation source. Results showed that predicted ultrasound fields agreed quantitatively and qualitatively with measured fields for three commonly used transducer types: two planar radiators (one circular, 0.5 MHz, 1.9-cm diam.; and one square, 1 MHz, 1.2 cm on a side), and a sharply focused radiator (1.5 MHz, 10-cm diam., 10-cm radius of curvature). The agreements suggest that the secondary source-array method (SSAM) is applicable to a wide range of radiator sizes, shapes, and operating frequencies. The SSAM was also compared to these authors’ previous equivalent phased array methods (EPAM) [J. Acoust. Soc. Am. 102, 2734–2741 (1997); and Concentric ring equivalent phased array method (CREPAM), UFFC 46, 830–841 (1999)] which require matrix inversions. The SSAM proved to be much faster and equally or more nearly accurate than the previous methods.
Cavitation nucleation agents for nonthermal ultrasound therapy
Authors: Miller Douglas L. , Kripfgans Oliver D. , Fowlkes J. Brian , Carson Paul L.
Published: July 2002

The use of a nucleation-promoting agent can greatly enhance therapeutically useful nonthermal bioeffects. A blank agent (saline), Optison™ ultrasound contrast agent, a stabilized perfluoropentane droplet suspension (SDS), and retained air space were compared as nucleation agents in whole blood. Fresh canine whole blood with added agent was exposed in 1.3-ml disposable pipette bulbs to lithotripter shock waves (2-Hz rate; +24.4, −5.2 MPa peak pressure amplitudes). Cavitation activity was assessed by measuring hemolysis. The droplet suspension performed nearly as well as retained air when added at a concentration sufficient to provide a roughly equal volume of gas after vaporization. Optison™ also yielded nucleation, but a concentration of 10%–20% was needed for large enhancement of hemolysis comparable to 5% SDS. Exposure at room temperature, which was less than the 29 °C boiling point of perfluoropentane, eliminated the enhancement of the hemolysis effect relative to the blank. Application of 100-kPa excess pressure during exposure reduced but did not eliminate the nucleation ability of Optison™, SDS, or retained air. However, this small pressure (relative to the peak positive pressure of the shock waves) eliminated the hemolysis induced with the blank agent. The stabilized perfluoropentane droplet suspension appears to be a good nucleation agent for nonthermal ultrasound therapy applications.
A numerical study of three-dimensional Jeffery orbits in shear flow
Authors: Ingber M. S. , Mondy L. A.
Published: July 2002

We perform numerical simulations of rods and spheroids undergoing Jeffery orbits in a variety of shear flows. The numerical simulations are based on the boundary element method, which allows for the accurate modeling of the problem geometry. We compare the period of rotation for spheroids and rods, both far from walls and very close to walls. We find that the wall effects in three dimensions are minimal, even for flow in gaps not much larger than the longest dimension of the particle. We also show that two-dimensional simulations grossly overpredict the wall effects seen in three dimensions. Results are similar for both linear and nonlinear shear flows. We also briefly look at the orbital motion of a particle in close proximity to another particle, and show that, again, there is very little effect on the period of rotation, although the resulting centroid trajectories are very different from that of an isolated particle.
Improvement of X-ray powder diffraction patterns of the spin transition polymer [Fe(Htrz)3](ClO4)2⋅1.85H2O
Authors: Smit E. , Manoun B. , Verryn S. M. C. , de Waal D.
Published: July 2002

The effects of proper drying and grinding of [Fe(Htrz)3](ClO4)2⋅1.85H2O specimens on the quality of X-ray powder patterns are illustrated (Htrz=1H-1,2,4-Triazole). A procedure is suggested to achieve high-quality, reproducible X-ray powder patterns of the compound. The observed powder diffraction data of the compound are reported together with preliminary indices calculated for a monoclinic system with cell parameters a=15.8160 Å, b=20.6134 Å, c=13.0321 Å, β=103.83° and Volume=4125.633 Å3, with reliability factors: M15=10.4, F15=22.0 (0.0100; 68) and space group P21/m. This compound is very similar to the compound [Cu(Hyetrz)3](ClO4)2⋅3H2O and a comparison is made between the cell parameters of the two compounds
Influence of annealing on X-ray diffraction of natural alexandrite
Authors: Scalvi Rosa Maria Fernandes , de Oliveira Ruggiero Lígia , Siu Li Máximo
Published: July 2002

In this work we present results of X-ray diffraction using powder method, on natural alexandrite samples from Minas Gerais State (Brazil), as a function of a sequence of annealing. From these measurements we determine lattice parameters before (a=9.405 Å, b=5.471 Å, c=4.409 Å) and after annealing, and its structure is confirmed as orthorhombic. Measurements done after an annealing of 15 minutes at 700 °C and for 5 hours at 1000 °C indicate the migration of atoms present in the sample through different phases, which were also identified by Microprobe Analysis (WDS). However we have verified that such migration does not modify the structure. X-ray diffraction measurements have been carried out in conjunction with optical absorption in the UV–Vis as a function of annealing.
Pregnancy After Bariatric Surgery
Authors: Fisher Stephanie A. , Stetson Bethany T. , Kominiarek Michelle A.
Published: February 2023

This JAMA Insights Clinical Update discusses general adaptations for pregnancy after bariatric surgery, including recommendations regarding nutrition, maternal health, and fetal and neonatal risks.
Association of Commercial-to-Medicare Relative Prices With Health System Financial Performance
Authors: Blavin Fredric , Kane Nancy , Berenson Robert , Blanchfield Bonnie , Zuckerman Stephen
Published: February 2023

Importance

Various studies have documented the rise in commercial insurance prices during the past 2 decades; however, estimates on the association of rising costs with health systems’ financial health are lacking. This study calculated 2 measures from standardized Audited Financial Statements (AFSs)—operating margins and days of unrestricted cash on hand—to explore the associations.

Objective

To estimate the association between health systems’ financial condition and the ratio of commercial to Medicare relative prices.

Design, Setting, and Participants

This cross-sectional analysis combined standardized 2018 AFSs from a large sample of US health systems with publicly available relative price data to assess the association between their financial outcomes and commercial-to-Medicare relative inpatient prices. The 2018 AFSs were collected and standardized from a convenience sample of multihospital health systems and single hospitals that were included in round 4 of the RAND Hospital Price Transparency Study. Cross-sectional, multivariate regression models were estimated, controlling for payer mix and other system characteristics, and models were weighted by health systems’ 2018 adjusted admissions. The analyses were conducted July 2021 through November 2022.

Exposures

The commercial-to-Medicare relative price for inpatient services (2018-2020 pooled average), which represents the average amount paid by commercial plans as a percentage of what Medicare would have paid to the same health system for the same services.

Main Outcomes and Measures

Operating margins and days cash on hand, which capture complementary aspects of financial performance (profitability and liquidity).

Results

The study sample included 156 health systems in the US, representing diverse geography, size, and ownership type. Mean (SD) days cash on hand were 180.1 (113.3) and operating margins were 3.3% (3.6%) in 2018. Overall, a 1-unit increase in the commercial-to-Medicare relative price ratio was associated with a 21.3% (95% CI, 21.3% to 21.4%; P < .001) increase in days cash on hand and a 2.7 (95% CI, 2.7 to 2.7; P < .001) percentage point increase in average operating margins. Higher Medicaid payer mix share was associated with fewer days cash on hand (−3.3%; 95% CI, −3.3% to −3.3%; P < .001) and lower operating margins (−0.081; 95% CI, −0.082 to −0.081; P < .001).

Conclusions and Relevance

This cross-sectional study of health system financial data found that higher commercial-to-Medicare relative prices and a lower Medicaid payer share were associated with higher profits and more days cash on hand. These findings provide evidence against the claim that relatively higher commercial prices are primarily used to offset losses from public payers rather than to increase profits and liquidity.
Multidomain Efficacy and Safety of Guselkumab Through 1 Year in Patients With Active Psoriatic Arthritis With and Without Prior Tumor Necrosis Factor Inhibitor Experience: Analysis of the Phase 3, Randomized, Placebo‐Controlled DISCOVER‐1 Study
Authors: Ritchlin Christopher T. , Deodhar Atul , Boehncke Wolf‐Henning , Soriano Enrique R. , Kollmeier Alexa P. , Xu Xie L. , Zazzetti Federico , Shawi May , Jiang Yusang , Sheng Shihong , Helliwell Philip S.
Published: February 2023

Objective

To evaluate efficacy and safety of the interleukin‐23p19‐subunit inhibitor, guselkumab, in DISCOVER‐1 patients with active psoriatic arthritis (PsA) by prior use of tumor necrosis factor inhibitor (TNFi).

Methods

The phase 3, randomized, placebo‐controlled DISCOVER‐1 study enrolled patients with active PsA (swollen joint count ≥3, tender joint count ≥3, and C‐reactive protein level ≥ 0.3 mg/dl) despite standard therapies; approximately one‐third could have received two or fewer prior TNFi. Patients were randomized to 100 mg of guselkumab every 4 weeks (Q4W); 100 mg of guselkumab at week 0, at week 4, and every 8 weeks (Q8W); or placebo with crossover to guselkumab Q4W at week 24. Efficacy end points of ≥20% and ≥50% improvement in individual American College of Rheumatology (ACR) criteria and achieving the minimal disease activity (MDA) components were summarized by prior TNFi status.

Results

In DISCOVER‐1, 118 (31%) patients previously received one or two TNFi. As previously reported, rates for acheiving ≥20% improvement in the composite ACR response at week 24 and week 52 were similar in TNFi‐naive and TNFi‐experienced patients randomized to guselkumab Q4W (76% and 68%, respectively) and Q8W (61% and 58%, respectively). Similar trends were observed for response rates of ≥20% and ≥50% improvement in individual ACR criteria and for achieving individual MDA components at week 24; TNFi‐naive patients were more likely to achieve end points related to physical function and pain than TNFi‐experienced patients. Overall, response rates were maintained or increased through week 52 regardless of prior TNFi use. Through week 60 in guselkumab‐treated TNFi‐naive and TNFi‐experienced patients, 62% and 64%, respectively, reported one or more adverse events (AEs); 4% and 6% had serious AEs, respectively.

Conclusion

Through 1 year, 100 mg of guselkumab Q4W and Q8W provided sustained improvements across multiple domains in both TNFi‐naive and TNFi‐experienced patients with active PsA.
Flexible Polyurethane@Ti3C2Tx/Silver Nanowires Composite Films with Cocontinuous Segregated Structures for Superior Electromagnetic Interference Shielding and Joule Heating
Authors: Jing Jiayao , Ma Zhonglei , Jiang Ruochu , Zhang Yan , Shao Liang
Published: February 2023

The booming development of communication technology and electronic equipment has put forward higher requirements of flexibility, electromagnetic interference (EMI) shielding performances, and service reliability for the EMI shielding materials. Herein, the flexible polyurethane@Ti3C2Tx/silver nanowires (PU@Ti3C2Tx/AgNWs) composite films with cocontinuous segregated structures are developed by a facile layer‐by‐layer hydrogen bonding assembly followed by hot‐pressing approach using PU sponge as the 3D skeleton template. Benefiting from the cocontinuous segregated structures, the flexible composite films exhibit high electrical and mechanical properties, excellent EMI shielding, and Joule heating performances. The EMI SE of the composite films can reach as high as 88 dB in X‐band (8.2–12.4 GHz). At a supplied voltage of 4.0 V, the composite films exhibit a high steady‐state Joule heating temperature up to 116.7 °C. The flexible cocontinuous segregated composite films with high working stability show great application potentials in EMI shielding and Joule heating systems in aerospace, weapon equipment, and wearable devices.
2D Bi2O2Te Semiconductor with Single‐Crystal Native Oxide Layer
Authors: Zou Xiaobin , Liang Haikuan , Li Yan , Zou Yichao , Tian Fei , Sun Yong , Wang Chengxin
Published: February 2023

Following logic in the silicon semiconductor industry, the existence of native oxide and suitable fabrication technology is essential for 2D semiconductors in planar integronics, which are surface‐sensitive to typical coating technologies. To date, very few types of integronics are found to possess this feature. Herein, the 2D Bi2O2Te developed recently is reported to possess large‐area synthesis and controllable thermal oxidation behavior toward single‐crystal native oxides. This shows that surface‐adsorbed oxygen atoms are inclined to penetrate across [Bi2O2]n2n+ layers and bond with the underlying [Te]n2n− at elevated temperatures, transforming directly into [TeO4]n2n− with the basic architecture remaining stable. The oxide can be adjusted to form in an accurate layer‐by‐layer manner with a low‐stress sharp interface. The native oxide Bi2TeO6 layer (bandgap of ≈2.9 eV) exhibits visible‐light transparency and is compatible with wet‐chemical selective etching technology. These advances demonstrate the potential of Bi2O2Te in planar‐integrated functional nanoelectronics such as tunnel junction devices, field‐effect transistors, and memristors.
Bioinspired MXene‐Based Piezoresistive Sensor with Two‐stage Enhancement for Motion Capture
Authors: Wang Shenglong , Deng Weili , Yang Tao , Ao Yong , Zhang Hongrui , Tian Guo , Deng Lin , Huang Haichao , Huang Junfeng , Lan Boling , Yang Weiqing
Published: February 2023

Structured piezoresistive membranes are compelling building blocks for wearable bioelectronics. However, the poor structural compressibility of conventional microstructures leads to rapid saturation of detection range and low sensitivity of piezoresistive devices, limiting their commercial applications. Herein, a bioinspired MXene‐based piezoresistive device is reported, which can effectively boost the sensitivity while broadening the response range by architecting intermittent villus‐like microstructures. Benefitting from the two‐stage amplification effect of this intermittent architecture, the developed MXene‐based piezoresistive bioelectronics exhibit a high sensitivity of 461 kPa−1 and a broad pressure detection range of up to 311 kPa, which are about 20 and 5 times higher than that of the homogeneous microstructures, respectively. Cooperating with the deep‐learning algorithm, the designed bioelectronics can effectively capture complex human movements and precisely identify human motion with a high recognition accuracy of 99%. Evidently, this intermittent architecture of biomimetic strategy may pave a promising avenue to overcome the limitation of rapid saturation and low sensitivity in piezoresistive bioelectronics, and provide a general way to promote its large‐scale applications.
Biosafe Saccharomyces Cerevisiae Immobilized Nanofibrous Aerogels for Integrated Lead Removal in Human Body
Authors: Cao Shiyi , Wu Shuangquan , Dong Xiangyang , Long Min , Lin Heng , Liu Fangtian , Wu Yang , Zhao Ze , Chen Chaoji , Deng Hongbing
Published: February 2023

Emerging adsorption technology shows great potential for Pb2+ removal in the human body because of its high adsorption efficiency and easy operation. However, biosafety concerns in the human body limit the development of adsorbents in integrated lead removal for acute poisoning in humans from the gastrointestinal tract and even the blood. In this work, highly bio‐safe and natural saccharomyces cerevisiae cells are immobilized on the interworking natural regenerated cellulose nanofibers network for integrated lead removal in the human body. High intrinsic biosafety of the aerogel is guaranteed due to the biocompatibility of aerogel composition and the absence of cross‐linking substances. Attributing to the porous structure of cellulose nanofibrous scaffolds, saccharomyces cerevisiae cells are protected from shedding, and considerable loading sites for saccharomyces cerevisiae cells are ensured. Simultaneously, abundant functional groups on the saccharomyces cerevisiae cells exhibit superior adsorption ability with a saturated adsorption capacity of lead ions as high as 107 mg g−1 in the aquatic environment. After adsorption, Pb2+ concentration decreases from 879.70 to 248.53 µg L−1 in the intestinal phase and from 400 to 186.29 µg L−1 (within a safe level) in blood, providing an attractive strategy for detoxification of integrated lead in the human body.
Electric Control of 2D Van Hove Singularity in Oxide Ultra‐Thin Films
Authors: Kim Donghan , Kim Younsik , Sohn Byungmin , Kim Minsoo , Kim Bongju , Noh Tae Won , Kim Changyoung
Published: February 2023

Divergent density of states (DOS) can induce extraordinary phenomena such as significant enhancement of superconductivity and unexpected phase transitions. Moreover, van Hove singularities (VHSs) lead to divergent DOS in 2D systems. Despite recent interest in VHSs, only a few controllable cases have been reported to date. In this work, by utilizing an atomically ultra‐thin SrRuO3 film, the electronic structure of a 2D VHS is investigated with angle‐resolved photoemission spectroscopy and transport properties are controlled. By applying electric fields with alkali metal deposition and ionic‐liquid gating methods, the 2D VHS and the sign of the charge carrier are precisely controlled. Use of a tunable 2D VHS in an atomically flat oxide film could serve as a new strategy to realize infinite DOS near the Fermi level, thereby allowing efficient tuning of electric properties.
Sub‐Nanosecond 2D Perovskite Scintillators by Dielectric Engineering
Authors: Xia Mengling , Xie Zuoxiang , Wang Hanqi , Jin Tong , Liu Linyue , Kang Jun , Sang Ziru , Yan Xianchang , Wu Boning , Hu Hao , Tang Jiang , Niu Guangda
Published: February 2023

Perovskite materials have demonstrated great potential for ultrafast scintillators with high light yield. However, the decay time of perovskite still cannot be further minimized into sub‐nanosecond region, while sub‐nanosecond scintillators are highly demanded in various radiation detection, including high speed X‐ray imaging, time‐of‐flight based tomography or particle discrimination, and timing resolution measurement in synchrotron radiation facilities, etc. Here, a rational design strategy is showed to shorten the scintillation decay time, by maximizing the dielectric difference between organic amines and Pb‐Br octahedral emitters in 2D organic‐inorganic hybrid perovskites (OIHP). Benzimidazole (BM) with low dielectric constant inserted between [PbBr6]2− layers, resulting in a surprisingly large exciton binding energy (360.3 ± 4.8 meV) of 2D OIHP BM2PbBr4. The emitting decay time is shortened as 0.97 ns, which is smallest among all the perovskite materials. Moreover, the light yield is 3190 photons MeV−1, which is greatly higher than conventional ultrafast scintillator BaF2 (1500 photons MeV−1). The rare combination of ultrafast decay time and considerable light yield renders BM2PbBr4 excellent performance in γ‐ray, neutron, α‐particle detection, and the best theoretical coincidence time resolution of 65.1 ps, which is only half of the reference sample LYSO (141.3 ps).
Unveiling the Morphological and Physical Mechanism of Burn‐in Loss Alleviation by Ternary Matrix Toward Stable and Efficient All‐Polymer Solar Cells
Authors: Ma Ruijie , Fan Qunping , Dela Peña Top Archie , Wu Baohua , Liu Heng , Wu Qiang , Wei Qi , Wu Jiaying , Lu Xinhui , Li Mingjie , Ma Wei , Li Gang
Published: February 2023

All‐polymer solar cells (All‐PSCs) are considered the most promising candidate in achieving both efficient and stable organic photovoltaic devices, yet the field has rarely presented an in‐depth understanding of corresponding device stability while efficiency is continuously boosted via the innovation of polymer acceptors. Herein, a ternary matrix is built for all‐PSCs with optimized morphology, improved film ductility and importantly, boosted efficiency and better operational stability than its parental binary counterparts, as a platform to study the underlying mechanism. The target system PQM‐Cl:PTQ10:PY‐IT (0.8:0.2:1.2) exhibits an alleviated burn‐in loss of morphology and efficiency under light soaking, which supports its promoted device lifetime. The comprehensive characterizations of fresh and light‐soaked active layers lead to a clear illustration of opposite morphological and physical degradation direction of PQM‐Cl and PTQ10, thus resulting in a delicate balance at the optimal ternary system. Specifically, the enlarging tendency of PQM‐Cl and shrinking preference of PTQ10 in terms of phase separation leads to a stable morphology in their mixing phase; the hole transfer kinetics of PQM‐Cl:PY‐IT host is stabilized by incorporating PTQ10. This work succeeds in reaching a deep insight into all‐PSC's stability promotion by a rational ternary design, which booms the prospect of gaining high‐performance all‐PSCs.
High‐Performance Hydrogel SERS Chips with Tunable Localized Surface Plasmon Resonance for Coordinated Electromagnetic Enhancement with Chemical Enhancement
Authors: Chen Mingming , Liu Zhihong , Su Bihang , Hu Rongjing , Fu Fengfu , Jiang Xiancai , Lin Zhenyu , Dong Yongqiang
Published: February 2023

Hydrogel surface‐enhanced Raman scattering (SERS) chips with tunable localized surface plasmon resonance (LSPR) wavelength are prepared to coordinate the chemical enhancement (CM) and electromagnetic enhancement (EM) effects for molecules. When detecting different molecules, a laser with matched energy is selected according to energy intervals between the molecular energy levels and the Fermi level of Ag nanoparticles to obtain the strongest CM effect. Meanwhile, a hydrogel SERS chip with the LSPR wavelength matching with the laser is selected to gain the strongest EM effect. As a result, the constructed hydrogel SERS chips show outstanding activity to many molecules. Amoxicillin, pymetrozine, and chlorpyrifos are used as the model molecules to demonstrate the great importance of CM effect and the working principle of the obtained hydrogel SERS chips. Besides the ultrahigh activity, the obtained hydrogel SERS chips also show high uniformity, long‐term stability, and strong anti‐interference to the sample matrix, and thereby are highly practical. This work not only provides an efficient strategy for building high‐performance SERS substrates, but also sheds the light on the mechanism of wave selection of SERS.
Promoting Reversibility of Co‐Free Layered Cathodes by Al and Cation Vacancy
Authors: Wang Tongshuai , Yang Jia , Wang Hailong , Ma Wei , He Miao , He Yufang , He Xiangming
Published: February 2023

Li‐ion batteries adopting layered cathodes can effectively alleviate the range limitations of electric vehicles. Unfortunately the scarcity of Co inhibits massive deployment of layered cathodes. Eliminating Co from layered cathodes is necessary to make a breakthrough in global application of electric vehicles. However, Co‐free layered cathodes face challenges in delithiation/lithiation reversibility since Co plays a pivotal role in suppressing Li/Ni mixing. Many metals have been proposed to replace Co in layered cathodes, and sophisticated compositional designs always consider suppressing Li/Ni mixing as the top priority. Here, the authors show that Li/Ni mixing can be suppressed by Al and cation vacancies in different manners; however, irreversible capacities are prominently different given similar Li/Ni mixing. In‐situ X‐ray diffraction monitored potentiostatic‐intermittent‐titration measurements reveal that Al decreases the lattice strain between H2 and H3 phase by 13.6%, but Al has an adverse impact on structure reversibility. While Al and cation vacancies together not only significantly reduce the H2/H3 lattice strain by 78% but also greatly enhance structure reversibility. Furthermore, the first‐principles calculation shows that cation vacancies can remarkably reduce the Li migration energy barrier by an order of magnitude. Reversibility of the newly designed Co‐free cathode is significantly enhanced through the synergic effect of Al and cation vacancies.
Mechanism of Cations Suppressing Proton Diffusion Kinetics for Electrocatalysis
Authors: Li Xiao‐Yu , Wang Tao , Cai Yu‐Chen , Meng Zhao‐Dong , Nan Jing‐Wen , Ye Jin‐Yu , Yi Jun , Zhan Dong‐Ping , Tian Na , Zhou Zhi‐You , Sun Shi‐Gang
Published: February 2023

Proton transfer is crucial for electrocatalysis. Accumulating cations at electrochemical interfaces can alter the proton transfer rate and then tune electrocatalytic performance. However, the mechanism for regulating proton transfer remains ambiguous. Here, we quantify the cation effect on proton diffusion in solution by hydrogen evolution on microelectrodes, revealing the rate can be suppressed by more than 10 times. Different from the prevalent opinions that proton transport is slowed down by modified electric field, we found water structure imposes a more evident effect on kinetics. FTIR test and path integral molecular dynamics simulation indicate that proton prefers to wander within the hydration shell of cations rather than to hop rapidly along water wires. Low connectivity of water networks disrupted by cations corrupts the fast‐moving path in bulk water. This study highlights the promising way for regulating proton kinetics via a modified water structure.
Copper‐Catalysed Rearrangement of Cyclic Ethynylethylene Carbonates: Synthetic Applications and Mechanistic Studies
Authors: Xu Chao , Zhang Hao , Lan Shouang , Liu Jinggong , Yang Shuang , Zhang Qi , Fang Xinqiang
Published: February 2023

Transition‐metal‐catalysed reactions of cyclic ethynylethylene carbonates have been intensively studied because of their robustness in new bond formation and diversified molecule construction. Known reaction modes usually involve a substitution step occurring at either the propargylic or terminal alkyne positions. Here, we report an unprecedented reaction pattern in which cyclic ethynylethylene carbonates first undergo a rearrangement to release allenal intermediates, which subsequently react with diverse nucleophiles to furnish synthetically useful allylic and propargylic allenols, phosphorus ylides, and cyclopropylidene ketones through an addition process rather than a substitution pathway. The products enable various further transformations, and mechanistic studies and theoretical calculations reveal that the reaction does not proceed via a semipinacol type [1,2]‐hydride shift, but through base‐mediated deprotonation as the key step to induce the rearrangement.
Catalytic Asymmetric Synthesis of Axially Chiral Diaryl Ethers through Enantioselective Desymmetrization
Authors: Bao Hanyang , Chen Yunrong , Yang Xiaoyu
Published: February 2023

Axially chiral diaryl ethers are a type of unique atropisomers bearing two potential axes, which have potential applications in a variety of research fields. However, the catalytic enantioselective synthesis of these diaryl ether atropisomers is largely underexplored when compared to the catalytic asymmetric synthesis of biaryl or other types of atropisomers. Herein, we report a highly efficient catalytic asymmetric synthesis of diaryl ether atropisomers through an organocatalyzed enantioselective desymmetrization protocol. The chiral phosphoric acid‐catalyzed asymmetric electrophilic aromatic aminations of the symmetrical 1,3‐benzenediamine type substrates afforded a series of diaryl ether atropisomers in excellent yields and enantioselectivities. The facile construction of heterocycles by the utilizations of the 1,2‐benzenediamine moiety in the products provided access to a variety of structurally diverse and novel azaarene‐containing diaryl ether atropisomers.
Single‐Molecule Two‐Color Coincidence Detection of Unlabeled alpha‐Synuclein Aggregates
Authors: Chappard Alexandre , Leighton Craig , Saleeb Rebecca S. , Jeacock Kiani , Ball Sarah R. , Morris Katie , Kantelberg Owen , Lee Ji‐Eun , Zacco Elsa , Pastore Annalisa , Sunde Margaret , Clarke David J. , Downey Patrick , Kunath Tilo , Horrocks Mathew H.
Published: February 2023

Protein misfolding and aggregation into oligomeric and fibrillar structures is a common feature of many neurogenerative disorders. Single‐molecule techniques have enabled characterization of these lowly abundant, highly heterogeneous protein aggregates, previously inaccessible using ensemble averaging techniques. However, they usually rely on the use of recombinantly‐expressed labeled protein, or on the addition of amyloid stains that are not protein‐specific. To circumvent these challenges, we have made use of a high affinity antibody labeled with orthogonal fluorophores combined with fast‐flow microfluidics and single‐molecule confocal microscopy to specifically detect α‐synuclein, the protein associated with Parkinson's disease. We used this approach to determine the number and size of α‐synuclein aggregates down to picomolar concentrations in biologically relevant samples.
Crystallization‐driven Nanoparticle Crystalsomes
Authors: Gao Lingfeng , Mei Shan , Qian Qian , Yu Shichen , Zhao Bin , Tu Yingfeng , Li Christopher Y.
Published: February 2023

Nanoparticle (NP) assembly has been extensively studied, and a library of NP superstructures has been synthesized. These intricate structures show unique collective optical, electronic, and magnetic properties. In this work, we report a bottom‐up approach for fabricating spherical gold nanoparticle (AuNP) assemblies that mimic colloidosomes. Co‐crystallization of lipoic acid‐end‐functionalized poly(ethylene oxide) (PEO) and AuNPs in solution via a self‐seeding method led to the formation of hollow spherical NP assemblies named nanoparticle crystalsomes (NPCs). Due to the spherical shape, the translational symmetry of PEO crystals is broken in NPCs, which can be attributed to the competition between NP close packing and polymer crystallization. This was confirmed by tuning the NPC morphology via varying the self‐seeding temperature, crystallization temperature, and PEO molecular weight. We envisage that this strategy paves the way to attaining exquisite morphological control of NP assemblies with broken translational symmetry.
Orthogonal Trichromatic Upconversion with High Color Purity in Core‐Shell Nanoparticles for a Full‐Color Display
Authors: Huang Kaofeng , Qiu Haiyi , Zhang Xintong , Luo Wang , Chen Ying , Zhang Jiacheng , Chen Yihang , Wang Guannan , Zheng Kezhi
Published: February 2023

Materials with tunable emission colors has attracted increasing interest in both fundamental research and applications. As a key member of light‐emitting materials family, lanthanide doped upconversion nanoparticles (UCNPs) have been intensively demonstrated to emit light in any color upon near‐infrared excitation. However, realizing the trichromatic emission in UCNPs with a fixed composition remains a great challenge. Here, without excitation pulsed modulation and three different near‐infrared pumping, we report an experimental design to fine‐control emission in the full color gamut from core–shell‐structured UCNPs by manipulating the energy migration through dual‐channel pump scheme. We also demonstrate their potential application in full‐color display. These findings may benefit the future development of convenient and versatile optical methos for multicolor tuning and open up the possibility of constructing full‐color volumetric display systems with high spatiotemporal resolution.
Total Syntheses of Kopsaporine, Kopsinol and Kopsiloscine A
Authors: Tian Hongchang , Wu Yinxia , Li Xiujuan , Hao Zhen , He Wenyan , Huang Xiangdi , Chen Wen , Zhang Hongbin
Published: February 2023

Kopsiaalkaloids represent a complex class of natural products bearing a polycyclic ring system with two or three consecutive quaternary carbon centers. In this article, we report the first total synthesis of Kopsaporine related alkaloids. Features of our structure‐unit‐based strategy are an intramolecular Pummerer rearrangement induced nucleophilic cyclization/aza‐Prins cyclization to construct the highly functional hexahydrocarbazole skeleton, an olefin migration vinylogous alkylation to establish the C20 all‐carbon quaternary center, an iridium complex mediated radical addition to fuse the aspidofractine framework, an unprecedented IBX oxidation to introduce the α‐hydroxyketone moiety, and a bioinspired retro‐Aldol/Aldol reaction to convert kopsaporine to kopsiloscine A.
Simple Ether‐Directed Enantioselective C(sp3)−H Borylation of Cyclopropanes Enabled by Iridium Catalysis
Authors: Xie Tian , Chen Lili , Shen Zhenlu , Xu Senmiao
Published: February 2023

Reported here is an efficient and simple ether‐directed iridium‐catalyzed enantioselective C(sp3)−H borylation of cyclopropanes. Various functional groups were well‐tolerated, affording a vast array of chiral cyclopropanes with high enantioselectivities. We also demonstrated that the turnover numbers of the current reaction could be up to 335.
Structural and Mechanistic Studies on Substrate and Stereoselectivity of the Indole Monooxygenase VpIndA1: New Avenues for Biocatalytic Epoxidations and Sulfoxidations
Authors: Kratky Julia , Eggerichs Daniel , Heine Thomas , Hofmann Sarah , Sowa Philipp , Weiße Renato H. , Tischler Dirk , Sträter Norbert
Published: February 2023

Flavoprotein monooxygenases are a versatile group of enzymes for biocatalytic transformations. Among these, group E monooxygenases (GEMs) catalyze enantioselective epoxidation and sulfoxidation reactions. Here, we describe the crystal structure of an indole monooxygenase from the bacterium Variovorax paradoxus EPS, a GEM designated as VpIndA1. Complex structures with substrates reveal productive binding modes that, in conjunction with force‐field calculations and rapid mixing kinetics, reveal the structural basis of substrate and stereoselectivity. Structure‐based redesign of the substrate cavity yielded variants with new substrate selectivity (for sulfoxidation of benzyl phenyl sulfide) or with greatly enhanced stereoselectivity (from 35.1 % to 99.8 % ee for production of (1S,2R)‐indene oxide). This first determination of the substrate binding mode of GEMs combined with structure‐function relationships opens the door for structure‐based design of these powerful biocatalysts.
Convective flow of ethylene glycol‐silver Jeffery nanofluid in a Hele‐Shaw cell with an influence of external magnetic field
Authors: Yadav Dhananjay , Al‐Balushi Sara , Awasthi Mukesh Kumar , Al‐Hadi Taif , Al‐Abri Raya , Al‐Wahaibi Jawhara , Al‐Nasseri Fatan , Al‐Siyabi Sara , Ragoju Ravi , Bhattacharyya Krishnendu
Published: February 2023

This effort investigates the arrival of magnetothermal convection of ethylene glycol‐silver Jeffrey nanofluid in a Hele‐Shaw cell utilizing the linear stability concept. The model practiced for the Jeffrey nanofluid includes the impacts of Brownian movement and thermophoresis. The norms for both marginal and overstable modes of convections are developed analytically. The impact of magnetic Chandrasekhar number
, magnetic Prandtl number
, Jeffrey parameter
, Hele‐Shaw number
, and a variety of nanofluid parameters such as the volumetric fraction of nanoparticles
, nanoparticle Rayleigh number
, adjusted diffusive ratio
, and Lewis number
on the beginning of convective motion are investigated, and results are illustrated graphically. It is observed that the overstable approach of convection is probable below the certain threshold estimate of the magnetic Prandtl number
. This threshold estimate of the magnetic Prandtl number
upturns with a rise in the rate of
,
, and
, while it drops with a surge in the nanofluid parameters. The system was found to be more stable by decreasing the Hele‐Shaw number
, the Jeffery parameter
, and nanofluid parameters, while it was unstable by decreasing the magnetic Chandrasekhar number
and the magnetic Prandtl number
.
Influence of unipolar electric fields on the behavior of dielectric elastomer actuators based on plasticized acrylonitrile‐butadiene rubber (NBR)
Authors: Vennemann Norbert , Kummerlöwe Claudia , Schneider Manuel , Bröker Dirk , Siebert Achim , Teich Sebastian , Rosemann Thomas
Published: February 2023

Commercial acrylonitrile‐butadiene rubber (NBR) containing large amount of plasticizer was used as base material for dielectric layers and compliant electrodes of dielectric elastomer actuators (DEA). The deformational behavior and dielectric properties of the DEA were characterized by combined measurements of polarization‐electric field (P‐E) as well as deformation‐electric field (S‐E) hysteresis loops. Unipolar electric fields were used to stimulate the actuators since theoretical considerations reveal that with unipolar fields larger deformations will be achieved compared to bipolar fields. Surprisingly, it turned out that the P‐E‐ and S‐E hysteresis loops exhibit a strong time dependency if a unipolar electric field is applied for actuators with a dielectric containing plasticizer. In contrast, no time dependency was observed for samples without plasticizer and in the case of bipolar fields. By means of additionally performed DC loss current measurements indication were obtained, that due to the unipolarity of the electric fields polar or ionized plasticizer molecules can be slightly accumulated at the anode. Finally, it is shown that application of unipolar electric fields results in larger actuator deformations compared to the case of simple bipolar sinusoidal stimulation. The experimental results are in good agreement with a theoretical approach which reveals that the resulting deformation is composed of the first harmonic and the second harmonic oscillation, superimposed by a constant offset value.
Exploring Spectrum‐based Molecular Descriptors for Reaction Performance Prediction
Authors: Tang Miao‐Jiong , Xu Li‐Cheng , Zhang Shuo‐Qing , Hong Xin
Published: February 2023

Despite the availability and accuracy of modern spectroscopic characterization, the utilization of spectral information in chemical machine learning is still primitive. Here, we report an optical character recognition‐based automatic process to utilize spectral information as molecular descriptors, which directly transforms experimental spectrum images to readable vectors. We demonstrate its machine learning application in the reaction yield dataset of Pd‐catalyzed Buchwald‐Hartwig cross‐coupling with aryl halides. In addition, we also show that the predicted spectrum can serve as an alternative encoding source to support the model training.
Application of nano‐radiosensitizers in combination cancer therapy
Authors: Varzandeh Mohammad , Sabouri Leila , Mansouri Vahid , Gharibshahian Maliheh , Beheshtizadeh Nima , Hamblin Michael R. , Rezaei Nima
Published: February 2023

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation‐induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano‐radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.
Autophagy: A challengeable paradox in cancer treatment
Authors: Ahmadi‐Dehlaghi Farnaz , Mohammadi Parisa , Valipour Elahe , Pournaghi Pouya , Kiani Sarah , Mansouri Kamran
Published: February 2023

Objective

Autophagy is an intracellular degradation pathway conserved in all eukaryotes from yeast to humans. This process plays a quality‐control role by destroying harmful cellular components under normal conditions, maintaining cell survival, and establishing cellular adaptation under stressful conditions. Hence, there are various studies indicating dysfunctional autophagy as a factor involved in the development and progression of various human diseases, including cancer. In addition, the importance of autophagy in the development of cancer has been highlighted by paradoxical roles, as a cytoprotective and cytotoxic mechanism. Despite extensive research in the field of cancer, there are many questions and challenges about the roles and effects suggested for autophagy in cancer treatment. The aim of this study was to provide an overview of the paradoxical roles of autophagy in different tumors and related cancer treatment options.

Methods

In this study, to find articles, a search was made in PubMed and Google scholar databases with the keywords Autophagy, Autophagy in Cancer Management, and Drug Design.

Results

According to the investigation, some studies suggest that several advanced cancers are dependent on autophagy for cell survival, so when cancer cells are exposed to therapy, autophagy is induced and suppresses the anti‐cancer effects of therapeutic agents and also results in cell resistance. However, enhanced autophagy from using anti‐cancer drugs causes autophagy‐mediated cell death in several cancers. Because autophagy also plays roles in both tumor suppression and promotion further research is needed to determine the precise mechanism of this process in cancer treatment.

Conclusion

We concluded in this article, autophagy manipulation may either promote or hinder the growth and development of cancer according to the origin of the cancer cells, the type of cancer, and the behavior of the cancer cells exposed to treatment. Thus, before starting treatment it is necessary to determine the basal levels of autophagy in various cancers.
The Genus Cryptocarya: A Review on Phytochemistry and Pharmacological Activities
Authors: Manh Ha Nguyen , The Son Ninh
Published: February 2023

Cryptocarya (the laurel family) is a large genus of great economic plants found in tropics and subtropics. Plants of this genus are a rich resource of essential oils, and pharmacological compounds. An overview of phytochemistry and pharmacological aspect is not yet available. This review aims to establish insightful information on phytochemistry, and pharmacological values. The literature collection is based on keywords ‘Cryptocarya’, ‘phytochemistry’, and ‘pharmacology’ using a broad panel of scientific sources, such as Google Scholar, Sciencedirect, and Wiley. Since the 1950s, Cryptocarya plants have been the main object in various phytochemical studies, by which about 390 metabolite compounds were isolated. Alkaloids, α‐pyrones, and flavonoids could be seen as the main classes of Cryptocarya isolates. Cryptocarya constituents displayed potential pharmacological values such as anti‐inflammatory, antimicrobial, antioxidative, antiviral, vasorelaxant activities, especially cytotoxicity.
Identification of the Authenticity and Geographical Origin of Bear Bile Powder by Using High Performance Liquid Chromatography ‐ Charged Aerosol Detector Fingerprints Combined with Chemometrics
Authors: Yuan Minghao , Zhou Tao , Lei Kelu , Liu Yushi , Li Meifeng , Zeng Dafu , Guo Yiping , Guo Li
Published: February 2023

Bear bile powder (BBP) is a rare animal‐derived traditional Chinese medicine, and it has been widely used to treat visual disorders and hepatobiliary diseases in East Asia. However, there is still a lack of reliable quality control methods for BBP. This study was designed to establish a comprehensive quality map of BBP based on bile acids. High‐performance liquid chromatography coupled with charged aerosol detector (HPLC‐CAD) was used for fingerprint establishment and quantitative analysis of BBP. The similarities of HPLC‐CAD chromatograms for 50 batches of BBP were more than 0.95, while the similarities of reference chromatograms between 6 other animal bile and BBP were low than 0.7. Additionally, five bile acids in BBP, including tauroursodeoxycholic acid, taurocholic acid, taurochenodeoxycholic acid, ursodesoxycholic acid, and chenodeoxycholic acid, were simultaneously quantified. This method has been validated with good regression as well as satisfactory precision, sensitivity, stability, repeatability, and accuracy. Using this method, the contents of five bile acids in BBP samples from five producing areas were determined and compared. Furthermore, Fisher linear discriminant analysis was performed to discriminate the geographic origins of BBP. The result demonstrated that HPLC‐CAD fingerprint combined with multi‐components quantification is an effective and reliable method for quality control of BBP, it could be a meaningful reference for the quality evaluation of medicinal bile.