bluuebunny/crossref_metadata_2025 huggingface dataset:
Approaches to the Modelling of the Hydrodynamic Properties of Rigid Biomacromolecules: Some Quantitative Comparisons
Authors: Tirrell Matthew , Torkelson John
Published: July 2002

Quantitative comparisons are made between calculations based on the best currently available predictive theories and experiments on the motions of rigid biomacromolecules and complexes through fluid media. Hydrodynamic properties calculated are translational diffusion coefficient, sedimentation coefficient, intrinsic viscosity, and rotational relaxation time. Structures for which calculations have been done are those representative of urease, polystyrene latex spheres with adsorbed γ-globulin, aspartate transcarbamylase, and once-broken rods. Conclusions are that sensitivity to structure in the hydrodynamic properties has the following order: first normal stress coefficient, Ψ1>rotational relaxation time, τ≫intrinsic viscosity, [η]>translational diffusion coefficient, DT∼sedimentation coefficient, S20.w0; and that a model proposed by Abdel-Khalik and Bird has good predictive capability except for structures which must be modelled by large numbers of subunits.
Numerical calculation of the startup flow of viscoelastic fluids in a circular pipe under constant flow rates (abstract)
Authors: Mori Noriyasu , Konishi Yoshiro , Kaige Takumi , Nakamura Kiyoji
Published: July 2002

The transient flow after imposing a constant flow rate on viscoelastic fluids initially at rest in a tube has been numerically calculated by using a finite difference method. The viscoelastic fluid model used is the Meister model with a memory function which depends on shear rate. The numerical calculation by the Meister model has shown that the center line velocity exhibits an overshoot, an oscillation, and a slight undershoot before reaching a steady state and that the complicated behavior in the velocity change has no significant effect on a pressure gradient change. Agreement between numerical calculations and experimental results is fairly good, though the overshoot in the calculation of pressure gradient is weak compared with the experimental data.
Viscoelastic properties of propylene-ethylene block copolymer melts (abstract)
Authors: Fujiyama Mitsuyoshi , Wakino Tetsuo , Kagiyama Yasuhiro
Published: July 2002

Stress relaxation and creep behavior of 16 commercial propylene-ethylene block copolymers was measured in a molten state. The relaxation moduli of samples with monomodal molecular weight distribution show plateau or shoulder at long times. The bimodality of molecular weight distribution in the latter samples is due to the ethylene-propylene copolymer component with high molecular weight. The plateau at long times is more noticeable as the bimodality is stronger. The height and width of the plateau is independent of the ethylene content. A PP-HDPE-EFR blend which was made as a model material of propylene-ethylene block copolymer does not show the plateau. The relaxation modulus at high temperature is always lower than that at low temperature, the time-temperature superposition can be performed well in all the measured range, and the shift factor obeys the Arrhenius equation. It was assumed from the above experimental results that appearance of the plateau at long times originates mainly from the bimodality of molecular weight distribution, not from the dispersion state of the ethylene-propylene copolymer particles.
Capillary flow properties of PVC melts (abstract)
Authors: Fujiyama Mitsuyoshi , Wakino Tetsuo
Published: July 2002

The effects of degree of polymerization and temperature on flow properties of PVC melts have been studied by using a Koka Flow Tester. Each flow curve is expressed by two straight lines of different slopes which meet at a breaking point. The critical shear rate γ̇wc′ at the breaking point increases as the degree of polymerization decreases or the temperature increases. The critical shear stress τc at γ̇wc′ increases as the degree of polymerization decreases, being almost independent of the temperature. The end correction coefficient ν shows a minimum or begins to increase around γ̇wc′. The coefficient ν increases as the degree of polymerization increases or the temperature decreases. The extrudate is smooth on the surface at low shear rates, shows a small wavy roughness (shark skin) at shear rates just below γ̇wc′, becomes fairly smooth again beyond γ̇wc′, and then shows intensive irregular roughness (melt fracture) at higher shear rates. The die swell becomes notable as degree of polymerization decreases or the temperature increases. The die swell takes a maximum at a shear rate just below γ̇wc′, where a shark skin appears on the extrudate. Differing from usual thermoplastic resin melts, PVC melts show a negative correlation between the die swell ratio and the end correction coefficient. This seems to be due to the following reason: PVC melts have high viscosities and have long relaxation times for strain recovery, and thus the extrudates solidify without being fully relaxed. This tendency of solidification without relaxation is more noticeable as the degree of polymerization increases or the temperature decreases.
Injection molding of liquid-crystalline polymer (abstract)
Authors: Horio Masao , Kamei Ei-ichi , Yao Shigeru
Published: July 2002

A liquid-crystalline copolyester consisting of 1,4-oxybenzoate and ethylene terephthalate groups was subjected to the injection molding using a rectangular mold 120×70×1 mm with a slot gate of 0.5-mm gap. The structures of injection-molded products were studied in detail by the x-ray diffraction method and the techniques of polarizing microscope. The molecules in the outer layers contiguous to both surfaces of injection-molded rectangular plate were highly oriented in the direction of injection and strongly birefringent, whilst the interior layer remained principally unoriented. The generation of characteristic binary structure with sharp boundaries was interpreted in terms of CAE data and the rheological behavior of the melt of liquid-crystalline polymer. The products of usual polymer made up of flexible molecules, on the contrary, gave isotropic products. The measurements of relaxation time afforded a key to an understanding of the difference between the behavior of liquid-crystalline polymer and that of usual polymer. The structural anisotropy of the products of liquid-crystalline polymer resulted in the anisotropy of mechanical properties. The structure produced by processing proved to be a determining factor for the mechanical properties of products in preference to the material of which the product was composed.
Effect of molecular association on rheological properties of chitosan/acetic acid aqueous solutions (abstract)
Authors: Matsumoto Takayoshi , Kawai Masahiro , Masuda Toshiro
Published: July 2002

Light scattering and rheological properties of chitosan solutions in 2% acetic acid aqueous solution were measured by means of a low angle laser light scattering photometer (Chromatix, KMX6) and a cone-plate Weissenberg Rheogoniometer (Sangamo Controls, R18). Chitosan samples of CS62 and CS79, which have degrees of deacetylation of 0.62 and 0.79, respectively, associate even in very low concentrations such as 10−5 g/ml and a degree of association is 2–3. On the other hand, the molecular association does not occur in a chitosan CS96, which has a relatively high degree of deacetylation of 0.96. Rheological properties show that the solutions of CS62 and CS96 are homogeneous and the solutions of CS79 are heterogeneous, with a certain relaxation mechanism having relatively long relaxation times. The effect of the molecular association and the heterogeneous structure on stress overshoot is also discussed.
Powder diffraction data for borides Pd3B and Pd5B2 and the formation of an amorphous boride Pd2B
Authors: Beck M. , Ellner M. , Mittemeijer E. J.
Published: July 2002

Powder diffraction data and refined unit cell parameters of two palladium borides were determined. For Pd3B (space group Pnma; Fe3C type) it was found that a=0.54602(3) nm, b=0.75596(4) nm, c=0.48417(4) nm and for Pd5B2 (space group C2/c; Mn5C2 type) a=1.27759(12) nm, b=0.49497(5) nm, c=0.54704(4) nm, β=97.049(7)°. Further, it was shown that the position of the principal scattering peak of the amorphous Pd2B fulfils the Nagel–Tauc criterion about glass forming ability.
Minor Changes in Daily Rhythms Induced by a Skeleton Photoperiod Are Associated with Increased Adiposity and Glucose Intolerance
Authors: Méndez‐Hernández Rebeca , Rumanova Valentina S. , Guzmán‐Ruiz Mara A. , Foppen Ewout , Moreno‐Morton Rodrigo , Hurtado‐Alvarado Gabriela , Escobar Carolina , Kalsbeek Andries , Buijs Ruud M.
Published: July 2022

Eating during the rest phase is associated with metabolic syndrome, proposed to result from a conflict between food consumption and the energy‐saving state imposed by the circadian system. However, in nocturnal rodents, eating during the rest phase (day‐feeding, DF) also implies food intake during light exposure. To investigate whether light exposure contributes to DF‐induced metabolic impairments, animals receive food during the subjective day without light. A skeleton photoperiod (SP) is used to entrain rats to a 12:12 cycle with two short light pulses framing the subjective day. DF‐induced adiposity is prevented by SP, suggesting that the conflict between light and feeding stimulates fat accumulation. However, all animals under SP conditions develop glucose intolerance regardless of their feeding schedule. Moreover, animals under SP with ad libitum or night‐feeding have increased adiposity. SP animals show a delayed onset of the daily rise in body temperature and energy expenditure and shorter duration of nighttime activity, which may contribute to the metabolic disturbances. These data emphasize that metabolic homeostasis can only be achieved when all daily cycling variables are synchronized. Even small shifts in the alignment of different metabolic rhythms, such as those induced by SP, may predispose individuals to metabolic disease.
Flame Retardant and Conductive Superhydrophobic Cotton Fabric with Excellent Electrothermal Property for Efficient Crude‐Oil/Water Mixture Separation and Fast Deicing
Authors: Zhu Xuedan , Luo Zhanxia , Yao Yali , Li Jiehui , He Jinmei , Qu Mengnan
Published: July 2022

Fabrics have been widely used in the fields of oil–water separation and deicing in recent years. Considering that the fabric is deeply affected by accidental fires, a flame retardant and conductive superhydrophobic cotton fabric with excellent electrothermal property cotton fabric containing Phytic acid/3‐Aminopropyltriethoxysilane (PA/APTES), carbon nanotube (CNT), and polydimethylsiloxane (PDMS) is developed. The peak heat release rate (PHRR) and total heat release (THR) values of PA/APTES/CNTs/PDMS‐coated fabric significantly declines by 63% and 76%, respectively, when compared to pristine cotton fabrics. Moreover, the heating uniformity on the PA/APTES/CNTs/PDMS‐coated fabric surface is validated by infrared thermography technology. Surprisingly, the CNTs layer also endow the coated fabric with excellent electrothermal capability, with its surface temperature rapidly rising from 22.8 to 500.7 °C within 10 s at a voltage of 25 V. Employing the generated Joule heat, the PA/APTES/CNTs/PDMS‐coated fabric can successfully separate crude oil and water, and the separation efficiency is much higher than that without voltage, about 9.5 times higher. In addition, the coated fabric also has excellent deicing performance. The ice cube with a volume of 12 cm3 is completely melted within 1380 s under 15 V voltage.
Interstitial Atomic Bi Charge‐Alternating Processor Boosts Twofold Molecular Oxygen Activation Enabling Rapid Catalytic Oxidation Reactions at Room Temperature
Authors: Lian Qiyu , Hu Lingling , Ma Dingren , Jiao Yimu , Xia Dehua , Huang Yajing , Tang Zhuoyun , Qu Wei , Zhao Huinan , He Chun , Gang Daniel D.
Published: July 2022

Molecular O2 activation on metallic oxide‐based catalysts surfaces is pivotal for catalytic oxidation reactions but highly depends on the O2 activation pathways or mechanisms. Thus, comprehensively understanding the mechanism of efficient O2 activation is conducive to extending the fundamental principles for O2 activation theories and designing novel catalysts for catalytic oxidation reactions. In this study, it is declared that the interstitial atomic Bi (IA Bi) anchored in the lattice interstice of MnO2 (Bi/MnO2) is capable of triggering an alternative twofold O2 activation boosting the catalytic oxidation reactions at room temperature. Explicitly, the IA Bi facilely induces the local lattice distortion reconstructing the local charge landscape, thus weakening the O2 dissociation energy barrier by elongating the OO bond length. And, the charge‐alternating process engineered by the IA Bi drives the alternative twofold O2 activation of the adjacent lattice oxygen and adsorbs dangling oxygen assisted by the consecutive O2 replenishment. Conclusively, this study not only declares the role of IA Bi in driving the charge‐alternating process during the twofold O2 activation but also extends the fundamental principles toward O2 activation mechanisms for catalytic oxidation reactions via atomic makeup engineering.
Ultranarrow Bandgap Se‐Deficient Bimetallic Selenides for High Performance Alkali Metal‐Ion Batteries
Authors: Yang Tao , Fang Miaojie , Liu Jianwen , Yang Dexin , Liang Yuhang , Zhong Jiasong , Yuan Yong‐Jun , Zhang Yanan , Liu Xiaolian , Zheng Rongkun , Davey Kenneth , Zhang Jian , Guo Zaiping
Published: July 2022

Metal selenides have attracted significant attention as practically promising anode materials in alkali metal‐ion batteries because of their high theoretical capacity. However, a drawback is that these do not provide sufficient rate performance and cycle stability for large‐scale. Here, anion defect‐tuned ultra‐narrow bandgap bimetallic selenide nanoparticles anchored on honeycomb‐like N‐doped, porous carbon dominated by pyrrolic nitrogen is reported. This targeted defect chemistry and unique structure facilitate rapid diffusion of lithium‐potassium ions to provide increased pseudo‐capacitance that boosts electrochemical performance. It is demonstrated that in lithium‐ and potassium‐ion batteries (LIB and KIB), the composite exhibits high specific capacity, and excellent cycle stability with a reversible capacity of 937 mA h g−1 at 2 A g−1 for LIB and 304 mA h g−1 at 1 A g−1 for KIB following 1000 cycles, together with superior rate capability of, respectively, 499 mA h g–1 for LIB and 139 mA h g–1 for KIB at 10 A g–1. A synergistic effect of the greater lithium/potassium ion adsorption energy of the bimetallic selenide and N‐doped carbon boosts ion diffusion kinetics of the materials is confirmed. It is concluded that, these findings will be of immediate benefit to the practical development of alkali‐metal ion batteries.
Dually‐Thermoresponsive Hydrogel with Shape Adaptability and Synergetic Bacterial Elimination in the Full Course of Wound Healing
Authors: Feng Lan , Chen Qin , Cheng Huitong , Yu Qiao , Zhao Weifeng , Zhao Changsheng
Published: July 2022

Incomplete contact between a pre‐formed hydrogel and irregular wound limits the therapeutic effect of the dressing and increases the risk of infection; while great concerns have remained regarding the potential toxicity of the residual additives of chemical crosslinking for in situ forming hydrogels. Therefore, it is desirable to develop a self‐adaptive hydrogel in response to skin temperature with shape adaptability and efficient antibacterial properties to prevent microbial invasion. Herein, a dually‐thermoresponsive hydrogel composed of poly(N‐isopropylacrylamide) (PNIPAm) and methacrylated κ‐carrageenan (MA‐κ‐CA) is designed with compliance at physiological temperature to realize shape adaptability for completely covering irregular wounds. Furthermore, the hydrogel with near‐infrared (NIR)‐responsive polypyrrole‐polydopamine nanoparticles (PPy‐PDA NPs) and Zn2+‐derived zeolitic imidazolate framework (ZIF‐8) can generate localized heat and gradually release Zn2+ to realize safe, effective synergetic photothermal–chemical bactericidal capability. In addition, the release rate of Zn2+ can be accelerated by NIR‐induced heating, and thus a more efficient sterilization can be provided to severely infected wounds. Therefore, the proposed hydrogel would serve as a promising wound dressing for the full course of wound healing, with the abilities of perfectly covering the wound and adapting to regenerating tissue, and controllable photothermal‐chemical antibacterial capability to reach high bactericidal efficiency and long‐term release of antibacterial agents.
Through the Lens of a Momentum Microscope: Viewing Light‐Induced Quantum Phenomena in 2D Materials
Authors: Karni Ouri , Esin Iliya , Dani Keshav M.
Published: July 2022

Van der Waals (vdW) materials at their 2D limit are diverse, flexible, and unique laboratories to study fundamental quantum phenomena and their future applications. Their novel properties rely on their pronounced Coulomb interactions, variety of crystal symmetries and spin‐physics, and the ease of incorporation of different vdW materials to form sophisticated heterostructures. In particular, the excited state properties of many 2D semiconductors and semi‐metals are relevant for their technological applications, particularly those that can be induced by light. In this paper, the recent advances made in studying out‐of‐equilibrium, light‐induced, phenomena in these materials are reviewed using powerful, surface‐sensitive, time‐resolved photoemission‐based techniques, with a particular emphasis on the emerging multi‐dimensional photoemission spectroscopy technique of time‐resolved momentum microscopy. The advances this technique has enabled in studying the nature and dynamics of occupied excited states in these materials are discussed. Then, the future research directions opened by these scientific and instrumental advancements are projected for studying the physics of 2D materials and the opportunities to engineer their band‐structure and band‐topology by laser fields.
SrTiO3/CuNi‐Heterostructure‐Based Thermopile for Sensitive Human Radiation Detection and Noncontact Human–Machine Interaction
Authors: Guo Xiaohan , Lu Xiaowei , Jiang Peng , Bao Xinhe
Published: July 2022

Noncontact interactive technology provides an intelligent solution to mitigate public health risks from cross‐infection in the era of COVID‐19. The utilization of human radiation as a stimulus source is conducive to the implementation of low‐power, robust noncontact human–machine interaction. However, the low radiation intensity emitted by humans puts forward a high demand for photodetection performance. Here, a SrTiO3−x/CuNi‐heterostructure‐based thermopile is constructed, which features the combination of high thermoelectric performance and near‐unity long‐wave infrared absorption, to realize the self‐powered detection of human radiation. The response level of this thermopile to human radiation is orders of magnitude higher than those of low‐dimensional‐materials‐based photothermoelectric detectors and even commercial thermopiles. Furthermore, a touchless input device based on the thermopile array is developed, which can recognize hand gestures, numbers, and letters in real‐time. This work offers a reliable strategy to integrate the spontaneous human radiation into noncontact human–machine interaction systems.
Ultrahigh‐Porosity MgO Microparticles for Heat‐Energy Storage
Authors: Kim Youngho , Dong Xue , Chae Sudong , Asghar Ghulam , Choi Sungwoong , Kim Bum Jun , Choi Jae‐Young , Yu Hak Ki
Published: July 2022

Continuous industrial development has increased the demand of energy. Inevitably, the development of energy sources is steadily progressing using various methods. Rather than establishing a new energy source, a system for storing waste heat generated by industry has now been accepted as a useful strategy. Among such systems, the hydration and dehydration reactions of MgO/Mg(OH)2 are eco‐friendly, have relatively low toxicity and risk, and have a large reserves. Therefore, it is a promising candidate for a heat‐storage system. In this study, ultrahigh‐porosity particles are used to maximize the heat‐storage efficiency of pure MgO. Due to its large surface area, the heat storage rate is 90.3% of the theoretical value and the reaction rate is very high. In addition, as structural collapse, likely to be caused by volume changes between reactions, is blocked as the porous region is filled and emptied, the cycle stability is secured. Ultrahigh‐porosity MgO microparticles can be used to build eco‐friendly heat‐storage systems.
Review on 2D Arsenene and Antimonene: Emerging Materials for Energy, Electronic and Biological Applications
Authors: Dongre S Sumanth , R Shwetharani , Hunsur Ravikumar Chandan , C Lavanya , Balakrishna R. Geetha
Published: July 2022

Monoelemental 2D materials such as arsenene (As) and antimonene (Sb) are creating great interest in materials research (since 2014) for designing various optoelectronic devices, energy production, and storage systems such as sensors, electrically modifiable displays, transistors, and catalysts owing to their unique properties like high surface area, optical, electrical, mechanical properties, and bio‐compatibility. Here in, an attempt has been made to write a comprehensive review on recent progress of monoelemental arsenene and antimonene focusing on tuning of properties through various techniques and their potential applications in different fields. The review is designed to explain the fundamental structures and properties in the beginning, followed by different preparation methods like exfoliation, ball milling, molecular beam epitaxy, chemical vapor deposition, and plasma‐assisted synthesis. Furthermore, the details on density functional theory studies of As an Sb and their applications in various fields such as photocatalysis, electronic and optoelectronic fields, solar cells, hydrogen evolution reaction, supercapacitors, batteries, biological applications, sensing, and electrochemical devices are reported.
Structural Defects Improve the Memristive Characteristics of Epitaxial La0.8Sr0.2MnO3‐Based Devices
Authors: Moncasi Carlos , Lefèvre Gauthier , Villeger Quentin , Rapenne Laetitia , Roussel Hervé , Bsiesy Ahmad , Jiménez Carmen , Burriel Mónica
Published: July 2022

Interface‐type valence change memories (VCMs) are exciting candidates for multilevel storage in resistive random access memories (RRAM) and as artificial synapses for neuromorphic computing. Several materials have been proposed as VCM candidates and, depending on the materials and electrodes of choice, different switching mechanisms take place leading to the change in resistance. Here, the focus is on La0.8Sr0.2MnO3–δ (LSM) perovskite and, particularly, the role of its nanostructure on the memristive device performance. The nanostructural details of the layers are modified by growing LSM epitaxial thin films on different substrates, i.e., SrTiO3 (STO) and LaAlO3 (LAO), by metal‐organic chemical vapor deposition (MOCVD). An interface‐type memristive response is observed using Ti as active electrode and Pt as inert electrode. The modifications in the nanostructure of LSM (strain and dislocations) determine the memristive performance, leading to differences in cycle to cycle reproducibility and multilevel capabilities by the modification of the LSM's oxygen migration properties. The results show that nanostructure engineering is a promising approach for optimizing the performance of memristive devices, an approach which can also be extended and applied to other nanoionic electrochemical devices.
Older populations of the invader Solidago canadensis exhibit stronger positive plant‐soil feedbacks and competitive ability in China
Authors: Oduor Ayub M. O. , Adomako Michael Opoku , Yuan Yongge , Li Jun‐Min
Published: July 2022

Premise

The enemy release hypothesis predicts that release from natural enemies, including soil‐borne pathogens, liberates invasive plants from a negative regulating force. Nevertheless, invasive plants may acquire novel enemies and mutualists in the introduced range, which may cause variable effects on invader growth. However, how soil microorganisms may influence competitive ability of invasive plants along invasion chronosequences has been little explored.

Methods

Using the invasive plant Solidago canadensis, we tested whether longer residence times are associated with stronger negative plant‐soil feedbacks and thus weaker competitive abilities at the individual level. We grew S. canadensis individuals from 36 populations with different residence times across southeastern China in competition versus no competition and in three different types of soils: (1) conspecific rhizospheric soils; (2) soils from uninvaded patches; and (3) sterilized soil. For our competitor treatments, we constructed synthetic communities of four native species (Bidens parviflora, Solanum nigrum, Kalimeris indica, and Mosla scabra), which naturally co‐occur with Solidago canadensis in the field.

Results

Solidago canadensis populations with longer residence times experienced stronger positive plant‐soil feedbacks and had greater competitive responses (i.e., produced greater above‐ground biomass and grew taller) in conspecific rhizospheric soils than in sterilized or uninvaded soils. Moreover, S. canadensis from older populations significantly suppressed above‐ground biomass of the native communities in rhizospheric and uninvaded soils but not in sterilized soil.

Conclusions

The present results suggest that older populations of S. canadensis experience stronger positive plant‐soil feedbacks, which may enhance their competitive ability against native plant communities.
Chemical Evolution of the Universe and its Consequences for Gravitational‐Wave Astrophysics
Authors: Chruślińska Martyna
Published: July 2022

Gravitational waves (GW) emitted by merging black holes (BH) and neutron stars are now routinely detected. Those are the afterlives of massive stars that formed all across the Universe—at different cosmic times and with different metallicities. Birth metallicity plays an important role in the evolution of massive stars. Consequently, the population properties of mergers are sensitive to the metallicity dependent cosmic star formation history (fSFR(Z,z)). In particular, within the isolated formation scenarios (the focus of this paper), a strong low metallicity preference of the formation of BH mergers is found. The origin of this dependence and its consequences are discussed. Most importantly, uncertainty in the fSFR(Z,z) (substantial even at low redshifts) cannot be ignored in the models. This poses a challenge for the interpretation of the observed GW source population properties. Possible improvements and the role of future GW detectors are considered. Recent efforts to determine fSFR(Z,z) and the factors that dominate its uncertainty are summarized. Many of those factors stem from the uncertain properties of faint and distant galaxies. The fact that they leave imprint on the redshift‐dependent properties of mergers makes GW a promising (and complementary to electromagnetic observations) tool to study galaxy chemical evolution.
Iron‐Catalyzed Cycloisomerization and C−C Bond Activation to Access Non‐canonical Tricyclic Cyclobutanes
Authors: Kramm Frederik , Ullwer Franziska , Klinnert Benedict , Zheng Min , Plietker Bernd
Published: July 2022

Cycloisomerizations are powerful skeletal rearrangements that allow the construction of complex molecular architectures in an atom‐economic way. We present here an unusual type of cyclopropyl enyne cycloisomerization that couples the process of a cycloisomerization with the activation of a C−C bond in cyclopropanes. A set of substituted non‐canonical tricyclic cyclobutanes were synthesized under mild conditions using [(Ph3P)2Fe(CO)(NO)]BF4 as catalyst in good to excellent yields with high levels of stereocontrol.
Controlling the Transition of Nanospheres to Superhelices in Aqueous Media by Using a “Smart” Pyrazine Building Block
Authors: Kumar Gaurav , Kumar Manoj , Bhalla Vandana
Published: July 2022

For the development of nature‐inspired chiral nanostructures, controlling the chirality communication along the assembling pathways in aqueous media is a crucial task. Herein, we designed and synthesized pyrazine‐based derivative Pyra‐Met with an L‐methionine group as a chiral handle. Due to the presence of flexible side chains in the Pyra‐Met building block, its interactions with the solvent molecules in the assembled state are restricted, which leads to the generation of nanospheres in aqueous media. The Pyra‐Met nanospheres selectively interact with Au3+ ions to generate dynamic helical fibers of the Pyra‐Met:Au3+ ensemble with ‘hidden’ chirality. Finally, superhelices with the desired helical sense are achieved in the presence of L/D‐methionine via a co‐assembly process. This work presents a feasible strategy to achieve the desired handedness of supramolecular assemblies for better understanding of chirality translation in supramolecular chemistry and it highlights the importance of fine tailoring of building block to control the morphology of the assembled architecture.
Synthesis and biological evaluation of Au‐NHC complexes
Authors: Ekinci Orhan , Akkoç Mitat , Khan Siraj , Yaşar Sedat , Gürses Canbolat , Noma Samir , Balcıoğlu Sevgi , Sen Betül , Aygün Muhittin , Yılmaz İsmet
Published: July 2022

New seven Au‐N‐heterocyclic carbene (NHC) complexes have been synthesized via transmetalation from Ag‐NHC complexes. NHC salts, Ag‐NHC, and Au‐NHC complexes were fully characterized by widely used spectroscopic techniques. The molecular and crystal structures of3band3fAu‐NHC complexes were clarified through the single‐crystal X‐ray diffraction method. According to X‐ray diffraction analysis results, the coordination geometry around Au(I) atoms in the complexes are revealed to be almost linear with C–Au–Cl angle. Anticancer activity, DNA binding, xanthine oxidase (XO) inhibitory activity studies, and molecular docking studies were evaluated for all Au‐NHC complexes to explore the binding mechanism at the active site. The IC50value of Au‐NHC complexes against human colorectal cancer (Caco‐2) and breast cancer (MCF‐7) cell lines was defined by MTT assay. The IC50values for MCF‐7 in the range of 5.2 ± 2 to 152.4 ± 1 μM and Caco‐2 5.2 ± 1 to 152.7 ± 2 μM showed that3a,3b,3c,3d, and3ghave better anticancer activity than Cisplatin incredibly complex3aagainst both cancer cell line. All Au‐NHC complexes showed excellent antimicrobial activity against different bacteria and fungi.3awas the complex that exhibited the best antimicrobial activity here as well. The XO inhibitory activity experimental results indicated that all gold complexes showed remarkable inhibition activity against XO compared to the generally used standard, allopurinol. The range of IC50value was determined from 0.407 to 2.681 μM.3dcomplex showed the lowest IC50 value at 0.407 μM. DNA binding experiments were performed using agarose gel electrophoresis to observe the ability of synthesized Au‐NHC complexes to interact with the supercoiled pUC19 plasmid DNA. Molecular docking studies were performed to determine the binding mode of all active compounds against the XO enzyme, antibacterial, antifungal, and MCF‐7 cell lines.
Dysregulation of Bile Acids, Lipids, and Nucleotides in Psoriatic Arthritis Revealed by Unbiased Profiling of Serum Metabolites
Authors: Paine Ananta , Brookes Paul S. , Bhattacharya Soumyaroop , Li Dongmei , De La Luz Garcia‐Hernandez Maria , Tausk Francisco , Ritchlin Christopher
Published: July 2022

Objective

The transition from psoriasis to psoriatic arthritis (PsA) occurs in 20–30% of patients; however, the mechanisms underlying the emergence of musculoskeletal disease are not well understood. Metabolic disease is prevalent in psoriasis patients, but whether metabolic factors, other than obesity, increase arthritis risk in psoriasis patients is not known. This study was undertaken to investigate the link between metabolic changes and disease progression in psoriasis patients.

Methods

To characterize the metabolic alterations during the progression of arthritis in psoriasis patients, we analyzed cross‐sectional healthy controls and PsA samples and longitudinal psoriasis serum samples, before and after PsA onset. Nontargeted metabolomic profiling was performed using liquid chromatography mass spectrometry.

Results

We identified several serum metabolites that differed between PsA patients, psoriasis patients, and healthy controls. Differentially abundant bile acids, purines, pyrimidines, glutathione, lipids, and amino acid metabolites were noted in these 3 groups. We also noted differences between psoriasis patients who progressed and those who did not progress to PsA. Bile acid and butyrate levels were depressed in those who progressed to PsA compared to those who did not, and the level of inflammatory lipid mediators increased following PsA diagnosis. In particular, the combination of leukotriene B4 and glycoursodeoxycholic acid sulfate were sensitive and specific predictors of PsA progression.

Conclusion

We observed notable differences in bile acid, purine, lipid, and amino acid–derived metabolites, among the healthy controls, psoriasis patients, and PsA patients and identified changes during the transition from psoriasis to PsA. The decreased bile acid and butyrate levels and elevated guanine levels in psoriasis patients at risk for PsA were particularly striking and may reflect gut microbial dysbiosis and dysregulated hepatic metabolism, leading to altered proliferation of immune cells and enhanced cytokine expression.
Photoactivatable Fluorogenic Azide‐Alkyne Click Reaction: A Dual‐Activation Fluorescent Probe
Authors: Xiao Mingjun , Zhang Yi‐Kang , Li Ranran , Li Shengtao , Wang Di , An Peng
Published: July 2022

Aryl azide and diaryl tetrazole are both photoactive molecules, which can form nitrene and nitrile imine intermediates respectively by photolysis. Depending on the new finding that the azide can suppress the photolysis of tetrazole in the azide‐tetrazole conjugated system, we developed aryl azide‐tetrazole probes for the photoactivatable fluorogenic azide alkyne click (PFAAC) reaction, in which the aryl azide‐tetrazole probes were not phoroactivatable fluorogenic itself, but the triazole products after click reaction were prefluorophore that can be activated by light. Therefore, in PFAAC chemistry, the fluorescent probes can be activated by two orthogonal events: azide‐alkyne click reaction and light, which leads to spatiotemporal resolution and high signal‐to‐noise ratio. This PFAAC process was proved in vitro by copper‐catalyzed or strain‐promoted azide‐alkyne reactions and in live cells by spatiotemporally controlled organelle imaging. By incorporation a linker to the azide‐tetrazole conjugate, this PFAAC chemistry could covalently label extra probes to the biomolecules and spatiotemporally detecting this process by photoinduced fluorescence.
A powerful global test for spliceQTL effects
Authors: de Menezes Renee X. , Rauschenberger Armin ,   BIOS Consortium, 't Hoen Peter A. C. , Jonker Marianne A.
Published: July 2022

Statistical methods to test for effects of single nucleotide polymorphisms (SNPs) on exon inclusion exist but often rely on testing of associations between multiple exon–SNP pairs, with sometimes subsequent summarization of results at the gene level. Such approaches require heavy multiple testing corrections and detect mostly events with large effect sizes. We propose here a test to find spliceQTL (splicing quantitative trait loci) effects that takes all exons and all SNPs into account simultaneously. For any chosen gene, this score‐based test looks for an association between the set of exon expressions and the set of SNPs, via a random‐effects model framework. It is efficient to compute and can be used if the number of SNPs is larger than the number of samples. In addition, the test is powerful in detecting effects that are relatively small for individual exon–SNP pairs but are observed for many pairs. Furthermore, test results are more often replicated across datasets than pairwise testing results. This makes our test more robust to exon–SNP pair‐specific effects, which do not extend to multiple pairs within the same gene. We conclude that the test we propose here offers more power and better replicability in the search for spliceQTL effects.
Top‐management compensation and environmental innovation strategy
Authors: Phung Giang , Trinh Hai Hong , Nguyen Tam Huy , Trinh Vu Quang
Published: July 2022

The increasing awareness of global climate change puts more pressure on firms to reduce their environmental externalities. Managers long ignored this responsibility, which may erode business profits, going against their traditional goals. In this study, we examine the effect of top management's extrinsic incentives (i.e., reward‐driven motivation) on corporate environmental innovation strategy (i.e., eco‐innovation) using a large dataset of S&P1500 non‐financial firms for 2000–2020. The results indicate that firms with greater levels of top‐management compensation exhibit higher scores of eco‐innovation engagement. The effect holds after we address the endogeneity problem through the quasi‐natural experiment using the difference‐in‐differences analysis on the event of the Paris Agreement 2015. Our further investigations reveal that such a positive impact of managerial incentives on eco‐innovation is less intensified in the more polluting industries but more pronounced in more innovative ones.
Design and optimization of membrane chromatography for monoclonal antibody charge variant separation
Authors: Nadar Sathish , Somasundaram Balaji , Charry Marcela , Billakanti Jagan , Shave Evan , Baker Kym , Lua Linda H. L.
Published: July 2022

The manufacturing scale implementation of membrane chromatography to purify monoclonal antibodies has gradually increased with the shift in industry focus toward flexible manufacturing and disposable technologies. Membrane chromatography are used to remove process‐related impurities such as host cell proteins (HCPs) and DNA, leachates, and endotoxins, with improved productivity and process flexibility. However, application of membrane chromatography to separate product‐related variants such as charge variants has not gained major traction due to low‐binding capacity. The work reported here demonstrates that a holistic process development strategy to optimize static binding (pH and salt concentration) and dynamic process (membrane loading, flowrate, and gradient length) parameters can alleviate the capacity limitations. The study employed high throughput screening tools and scale‐down membranes for intermediate and polishing purification of the model monoclonal antibody. An optimized process consisting of anion exchange and cation exchange membrane chromatography reduced the acidic variants present in Protein A eluate from 89.5% to 19.2% with 71% recovery of the target protein. The membrane chromatography process also cleared HCP to below limit of detection with 6‐ to 30‐fold higher membrane loading, compared to earlier reported values. The results confirm that membrane chromatography is effective in separating closely related product variants when supported by a well‐defined process development strategy.
Hydrogen sulfide prevents arecoline‐induced neurotoxicity via promoting leptin/leptin receptor signaling pathway
Authors: Cheng Xiang , Jiang Jia‐Mei , Wang Chun‐Yan , Zou Wei , Zhang Ping , Tang Xiao‐Qing
Published: July 2022

Arecoline, a major alkaloid of the areca nut, has potential toxicity to the nervous system. Our previous study reveals that the neurotoxicity of arecoline involves in inhibited endogenous hydrogen sulfide (H2S) generation. Therefore, the present study investigated whether exogenous H2S protects against arecoline‐induced neurotoxicity and further explore the underlying mechanisms focusing on leptin/leptin receptor signaling pathway. The cell viability was measured by CCK‐8 kit. The apoptosis were detected by Hoechst 33258 and Annexin V/PI (propidium iodide) staining. The protein expressions were determined by Western blot analysis. Our results demonstrated that NaHS, an exogenous H2S donor, significantly increases the cell viability, decreases apoptosis ratio, and reduces caspase‐3 activity as well as Bax/Bcl‐2 ratio in PC12 cells exposed to arecoline, indicating the protection of H2S against arecoline‐induced cytotoxicity and apoptosis. Also, NaHS attenuated arecoline‐induced endoplasmic reticulum (ER) stress, as evidenced by the decreases in the expressions of glucose‐regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), and Cleaved caspase‐12. Meanwhile, NaHS promoted leptin/leptin receptor signaling pathway in arecoline‐exposed PC12 cells, as illustrated by upregulations of leptin and leptin receptor expressions. Furthermore, leptin tA, an antagonist of leptin receptor, obviously abolished the inhibitory effects of NaHS on arecoline‐induced cytotoxicity, apoptosis, and ER stress in arecoline‐exposed PC12 cells. Taken together, these results suggested that H2S prevents arecoline‐induced neurotoxicity via enhancing the leptin/leptin receptor signaling pathway.
Assessment and management of the risk of unintended contamination of wheat by soy allergens in silos
Authors: Crépon Katell , Duyme Florent
Published: July 2022

Background and Objectives

In the European Union, soybean production has increased by almost 130% over the last 10 years which also increases the risk of commingling of grains, especially during storage. Soy is a major allergen and stakeholders are then confronted with an increased risk of unintended presence of allergen in cereal products. The aim of our work is to provide elements of evaluation and management of the allergen risk to silo managers faced with the storage of wheat and soya on the same facility.

Findings

We reproduced the cross‐contamination between batches of wheat and soybeans using the same handling circuit and measured the effectiveness of elevator cleaning and grain cleaning to reduce the contamination. Soy content (%) and soy protein content (mg/kg) in wheat were monitored.

Conclusions

The observed cross‐contamination rate was between 0.15% and 0.18% but was largely dependent on the tonnage of wheat, with the cross‐contamination rate decreasing rapidly as the grain was conveyed. Vacuum cleaning of pit elevators and grain cleaning significantly reduced the cross‐contamination rate but not enough to eliminate the allergenic risk in food products with a high wheat content.

Significance and Novelty

The rapid decay of the commingling rate allows the consideration of flushing procedures to manage cross‐contamination between batches. The model established on our results allows us to calculate the tonnage required to obtain a sufficiently effective flush to manage the risk of cross‐contamination.
Palladium‐Based Metal Organic Frameworks as Heterogeneous Catalysts for C−C Couplings
Authors: Lawrence Arputham Shophia , Martin Nuria , Sivakumar Balasubramanian , Cirujano Francisco G. , Dhakshinamoorthy Amarajothi
Published: July 2022

Among the various cross coupling reactions, C−C cross coupling reaction has attracted many researchers to investigate in the last four decades. The continuous, constant, and consistent progress in this field fetched a Noble prize in 2010, showing the importance of this reaction in diversified fields. Among the various transition metals studied for this reaction, Pd is one of the metals that has exhibited the highest activity due to its unique features and reactivity. Although Pd‐based homogeneous catalyst was the preferred choice for many researchers, the field slowly diverted towards the development of Pd‐based heterogeneous catalysts for C−C coupling reactions. This is obviously due to the high cost of Pd precursor, its self‐deactivation. In this context, metal organic frameworks (MOFs) are one of the solid catalysts frequently employed as host matrix for the deposition of Pd(II) salts and Pd nanoparticles. This is due to the widespread possibilities available for the functionalization of MOFs and their stability during the synthetic procedure. This review provides the design and development of Pd‐based MOFs as heterogeneous catalysts for the C−C cross coupling reactions. After a brief introduction on MOFs and the importance of C−C coupling reactions, the main part of the review summarizes the catalytic data with respect to Pd(II) and Pd nanoparticles as active sites. The last section provides our views in this field for the further development in the near future.
A Mean‐Field Model for Oxygen Reduction Electrocatalytic Activity on High‐Entropy Alloys**
Authors: Pedersen Jack K. , Clausen Christian M. , Skjegstad Lars Erik J. , Rossmeisl Jan
Published: July 2022

High‐entropy alloys (HEAs) represent near‐equimolar points in the middle of a vast composition space of multi‐metallic catalysts. Successful modeling of the catalytic activity of these complex materials allows to search this composition space for optimal catalysts. This study shows the effect of approximating the ligand effect of the surrounding atoms around an adsorption site with a mean‐field perturbation. Modeling the electrocatalytic activity of the oxygen reduction reaction on the quinary AgIrPdPtRu HEA, it is shown that the extent of such a mean‐field approximation is valid up to and including equimolar ternary alloys, corresponding to 60.3 % of the quinary composition space, by comparing to models that consider the ligand effect locally. When extrapolating to make predictions far from near‐equimolar compositions, such as for binary alloys, the mean field has been sufficiently perturbed to cause large discrepancies. Here, the local ligand models thus prove more useful for discovering optimal catalysts.
Chemical looping combustion characteristics and kinetic behaviour of Sr‐doped perovskite‐type CaFeO3 oxygen carriers: Theoretical and experimental investigations
Authors: Yuan Nini , Han Ziheng , Guo Qingjie , Jian Hao , Ma Jingjing , Bai Hongcun
Published: July 2022

Oxygen carriers (OCs) with typical perovskite structures have attracted attention for use in chemical looping combustion (CLC) owing to their unique tunable structures and excellent performance. Thus, a further improvement in the reactivity and a deep understanding of the kinetic behaviour in CLC are highly desirable for such perovskite OCs. In this study, a series of Sr‐doped perovskite‐structured CaFeO3 OCs (denoted as SrxCa1−xFeO3) were synthesized. The CLC characteristics, kinetic behaviour, and doping mechanism were systematically investigated via experiments and density functional theory (DFT) calculations. The activation energies of SrxCa1−xFeO3 OCs with various Sr contents were found to be in the range of 36.6–40.1 kJ/mol and lower than that of CaFeO3 (62.7 kJ/mol), indicating that the Sr doping enhanced the reactivity of CaFeO3. Among the OCs, Sr0.4Ca0.6FeO3, which had the lowest activation energy and the fastest release of lattice oxygen, was regarded as the optimum OC. DFT calculations indicated that the reaction energy barrier of SrxCa1−xFeO3 (0.73–1.06 eV) was lower than that of CaFeO3 (2.18 eV). This suggests that Sr doping and the regulation of the reaction pathways are essential drivers for enhancing the reactivity of SrxCa1−xFeO3, which affects the release of lattice oxygen and the morphological properties of OC particles.