bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemie und Begriffe entwickeln sich, aber Phänomene nicht: Von Chalkogen‐Chalkogen‐Wechselwirkungen zu “Chalcogen Bonding”
Authors: Kolb Simon , Oliver Gwyndaf A. , Werz Daniel B. 
Published: September 2020

AbstractChalcogen Bonding spielt in verschiedenen Bereichen der Chemie sowohl im Festkörper als auch in Lösung eine entscheidende Rolle. Bei genauer Literaturrecherche wird allerdings deutlich, dass – nachdem sich der Begriff von “Chalkogen‐Chalkogen‐Wechselwirkungen” zum prägnanteren “Chalcogen Bonding” verkürzt hatte – ein Teil der wissenschaftlichen Gemeinschaft sich an die Herkunft dieses Phänomens nicht mehr erinnert und dieses in seiner ursprünglichen Form auch nicht mehr referenziert. In diesem Viewpoint verfolgen wir exemplarisch die wissenschaftliche Entwicklung ausgehend von diesem Phänomen – beginnend mit seiner Entdeckung, über die Abänderung des Begriffs bis zur aktuellen und faszinierenden Forschung in Bereichen wie Crystal Engineering, dem Design supramolekularer Strukturen und der modernen Katalyse.
Mechanism of 3‐Methylglutaconyl CoA Decarboxylase AibA/AibB: Pericyclic Reaction versus Direct Decarboxylation
Authors: Sheng Xiang , Himo Fahmi 
Published: September 2020

AbstractThe enzyme 3‐methylglutaconyl coenzyme A (CoA) decarboxylase (called AibA/AibB) catalyzes the decarboxylation of 3‐methylglutaconyl CoA to generate 3,3‐dimethylacrylyl‐CoA, representing an important step in the biosynthesis of isovaleryl‐coenzyme A in Myxococcus xanthus when the regular pathway is blocked. A novel mechanism involving a pericyclic transition state has previously been proposed for this enzyme, making AibA/AibB unique among decarboxylases. Herein, density functional calculations are used to examine the energetic feasibility of this mechanism. It is shown that the intramolecular pericyclic reaction is associated with a very high energy barrier that is similar to the barrier of the same reaction in the absence of the enzyme. Instead, the calculations show that a direct decarboxylation mechanism has feasible energy barriers that are in line with the experimental observations.
Solid‐State Radical C−H Trifluoromethylation Reactions Using Ball Milling and Piezoelectric Materials
Authors: Pang Yadong , Lee Joo Won , Kubota Koji , Ito Hajime 
Published: September 2020

AbstractThe application of piezoelectricity for the generation of trifluoromethyl (CF3) radicals is reported together with the development of a method for the mechanochemical C−H trifluoromethylation of aromatic compounds. As compared to conventional solution‐based approaches, this mechanoredox C−H trifluoromethylation enables cleaner and more sustainable access to a wide range of trifluoromethylated N‐heterocycles and peptides, which are important structural motifs in modern drug discovery. This study thus represents an important milestone for future applications of mechanoredox systems to medicinal and pharmaceutical science.
Breathing Micelles for Combinatorial Treatment of Rheumatoid Arthritis
Authors: Tao Siyue , Cheng Jian , Su Gai , Li Dan , Shen Zhiqiang , Tao Fenghua , You Tao , Hu Jinming 
Published: September 2020

AbstractBreathing process involves inhalation and exhalation of different gases in animals. The gas exchange of the breathing process plays a critical role in maintaining the physiological functions of living organisms. Although artificial breathing materials exhibiting volume expansion and contraction upon alternate exposure to different gases have been well explored, those being able to realize the gas exchange remain elusive. Herein, we report breathing micelles (BM) capable of inhaling nitric oxide (NO) and exhaling carbon monoxide (CO), both of which are endogenous gaseous signaling molecules. We demonstrate that BM can simultaneously scavenge overproduced NO and attenuate proinflammatory cytokines in lipopolysaccharide (LPS)‐challenged macrophage cells. In vivo studies revealed that BM outperformed conventional nonsteroidal anti‐inflammatory drugs such as dexamethasone (Dexa) in treatment of rheumatoid arthritis (RA) in adjuvant‐induced arthritis (AIA) rats, likely due to the combinatorial effect of NO depletion, CO‐mediated deactivation of inducible NO synthase (iNOS) and activation of heme oxygenase‐1 (HO‐1). This work provides new insights into artificial BM for potential biomedical applications.
Configurational Entropy Driven High‐Pressure Behaviour of a Flexible Metal–Organic Framework (MOF)
Authors: Vervoorts Pia , Keupp Julian , Schneemann Andreas , Hobday Claire L. , Daisenberger Dominik , Fischer Roland A. , Schmid Rochus , Kieslich Gregor 
Published: September 2020

AbstractFlexible metal–organic frameworks (MOFs) show large structural flexibility as a function of temperature or (gas)pressure variation, a fascinating property of high technological and scientific relevance. The targeted design of flexible MOFs demands control over the macroscopic thermodynamics as determined by microscopic chemical interactions and remains an open challenge. Herein we apply high‐pressure powder X‐ray diffraction and molecular dynamics simulations to gain insight into the microscopic chemical factors that determine the high‐pressure macroscopic thermodynamics of two flexible pillared‐layer MOFs. For the first time we identify configurational entropy that originates from side‐chain modifications of the linker as the key factor determining the thermodynamics in a flexible MOF. The study shows that configurational entropy is an important yet largely overlooked parameter, providing an intriguing perspective of how to chemically access the underlying free energy landscape in MOFs.
Multispecific Platinum(IV) Complex Deters Breast Cancer via Interposing Inflammation and Immunosuppression as an Inhibitor of COX‐2 and PD‐L1
Authors: Jin Suxing , Muhammad Nafees , Sun Yuewen , Tan Yehong , Yuan Hao , Song Dongfan , Guo Zijian , Wang Xiaoyong 
Published: September 2020

AbstractBreast cancer (BC) is one of the most common malignancies in women and often accompanied by inflammatory processes. Cyclooxygenase‐2 (COX‐2) plays a vital role in the progression of BC, correlating with the expression of programmed death‐ligand 1 (PD‐L1). Overexpression of PD‐L1 contributes to the immune escape of cancer cells, and its blockade would stimulate anticancer immunity. Two multispecific platinum(IV) complexes DNP and NP were prepared using non‐steroidal antiinflammatory drug naproxen (NPX) as axial ligand(s) to inhibit the BC cells. DNP exhibited high cytotoxicity and antiinflammatory properties superior over NP, cisplatin and NPX; moreover, it displayed potent antitumor activity and almost no general toxicity in mice bearing triple‐negative breast cancer (TNBC). Mechanistic studies revealed that DNP could downregulate the expression of COX‐2 and PD‐L1 in vitro and vivo, inhibit the secretion of prostaglandin, reduce the expression of BC‐associated protein BRD4 and phosphorylation of extracellular signal‐regulated kinases 1/2 (Erk1/2), and block the oncogene c‐Myc in BC cells. These findings demonstrate that DNP is capable of intervening in inflammatory, immune, and metastatic processes of BC, thus presenting a new mechanism of action for anticancer platinum(IV) complexes. The multispecificity offers a special superiority for DNP to treat TNBC by combining chemotherapy and immunotherapy in one molecule.
Guest‐Reaction Driven Cage to Conjoined Twin‐Cage Mitosis‐Like Host Transformation
Authors: Cheng Pei‐Ming , Cai Li‐Xuan , Li Shao‐Chuan , Hu Shao‐Jun , Yan Dan‐Ni , Zhou Li‐Peng , Sun Qing‐Fu 
Published: September 2020

AbstractWe report here a guest‐reaction‐induced mitosis‐like host transformation from a known Pd4L2 cage 1 to a conjoined Pd6L3 twin‐cage 2 featuring two separate cavities. The encapsulation of 1‐hydroxymethyl‐2‐naphthol (G1), a known ortho‐quinone methide (o‐QMs) precursor, within the hydrophobic cavity of cage 1 is found crucial to realize the cage to twin‐cage conversion. Confined G1 molecules within the nanocavity undergo self‐coupling dimerization reaction to form 2,2′‐dihydroxy‐1,1′‐dinaphthylmethane (G2) which then triggers the cage to twin‐cage mitosis. The same conversion also proceeds, in a much faster rate, via the direct templation of G2, confirming the induced‐fit transformation mechanism. The structure of the (G2)2⊂2 host–guest complex has been established by X‐ray crystallographic study, where cis‐ to trans‐ conformational switch on one bridging ligand is revealed.
Oligosilanes as Silyl Radical Precursors through Oxidative Si−Si Bond Cleavage Using Redox Catalysis
Authors: Yu Xiaoye , Lübbesmeyer Maximilian , Studer Armido 
Published: September 2020

AbstractOligosilanes are of great interest in the fields of organic photonics and electronics. In this communication, a highly efficient visible‐light‐mediated hydrosilylation of electron‐deficient alkenes through cleavage of a trimethylsilyl‐polysilanyl Si−Si bond is explored. These reactions smoothly occur on readily available organo(tristrimethylsilyl)silanes and other oligosilanes in the presence of an IrIII‐based photo‐redox catalyst under visible light irradiation. Silyl radicals are generated through single electron oxidation of the oligosilane assisted by the solvent. The introduced method exhibits broad substrate scope and high functional group tolerance with respect to the organo(tristrimethylsilyl)silane and alkene components, enabling the construction of functionalized trisilanes. In addition, this catalytic system can be also applied to highly strained bicyclo[1.1.0]butanes as silyl radical acceptors.
Selective and Scalable Synthesis of Sugar Alcohols by Homogeneous Asymmetric Hydrogenation of Unprotected Ketoses
Authors: Tindall Daniel J. , Mader Steffen , Kindler Alois , Rominger Frank , Hashmi A. Stephen K. , Schaub Thomas 
Published: September 2020

AbstractSugar alcohols are of great importance for the food industry and are promising building blocks for bio‐based polymers. Industrially, they are produced by heterogeneous hydrogenation of sugars with H2, usually with none to low stereoselectivities. Now, we present a homogeneous system based on commercially available components, which not only increases the overall yield, but also allows a wide range of unprotected ketoses to be diastereoselectively hydrogenated. Furthermore, the system is reliable on a multi‐gram scale allowing sugar alcohols to be isolated in large quantities at high atom economy.
Comparison of label‐free and label‐based approaches for surface‐enhanced Raman microscopic imaging of bacteria cells
Authors: Hickey Michael E. , Gao Siyue , He Lili 
Published: September 2020

AbstractSurface‐enhanced Raman spectroscopic (SERS) approaches are emerging for bacteria analysis whereby bacteria cells can be measured based on their biochemical composition (label‐free) or with the aid of a chemical label to enhance the SERS signal. Combining a microscope, SERS microscopy is capable of imaging bacteria populations en masse based on specific spectrophotometric peaks. Here, we compared the label‐free and label‐based approaches to study Escherichia coli O157:H7 that was utilized as a model bacterium for SERS imaging analyses. Gold (Au) nanoparticles were utilized to enhance Raman scattering during this study and 3‐mercaptophenylboronic acid was utilized as a model chemical label for comparison against label‐free conditions. The result shows that SERS images of bacteria cells yielded measurable differences in precision, depending on the application of chemical labels. Chemical labels enabled SERS imaging of whole bacteria populations with single‐cell precision. Bacteria coated with labels were also easier to bring into focus using high‐magnification optical microscopy, without the need for immersion oil. Label‐free analyses of single‐cells were lower in geographic precision but provided opportunities to study the natural biochemistry of bacteria cells with strong accuracy. SERS analyses of label‐free bacteria cell components were conclusively improved in vitro on a time‐dependent basis. This concept can serve as an important benchmark when biochemically profiling or characterizing bacteria cells based on SERS. Electron micrographs proved that chemical labels can be utilized to increase nanoparticle contact with bacteria cells and reduce free nanoparticles that contribute to background noise in SERS spectra. We also demonstrate the use of both 3‐mercaptophenylboronic acid and propidium iodide to discriminate live and dead bacteria through the simultaneous collection of data from these two chemical labels. Label‐free approaches to SERS bacteria analyses are better suited for biochemical characterization and label‐based approaches are better suited when accounting for individual cells among a population.
Examining the Incidence and Clients’ Experiences of Single Session Therapy in Italy: A Feasibility Study
Authors: Cannistrà Flavio , Piccirilli Federico , Paolo D’Alia Pier , Giannetti Angelica , Piva Lorenza , Gobbato Ferruccio , Guzzardi Roberta , Ghisoni Alice , Pietrabissa Giada 
Published: September 2020

Single session therapy (SST) postulates that one session can be sufficient for a client to take charge of the process and work toward their own solutions. Research has been conducted worldwide corroborating SST assumptions with several mental health conditions, but not in Italy. For the first time in Italy, this paper aims to explore: (1) if the most frequent number of sessions in traditional psychotherapy (not SST) is one (Study 1); and (2) the satisfaction of clients who attend SST services and the number who consider one session sufficient to address their presenting problem (Study 2). In Study 1, the records of 476 voluntary clients referred to three different traditional (not SST) psychological services in the west‐central region of Latium, Italy, were retrospectively screened, and the number of sessions attended by each client recorded. In Study 2, 85 consecutive clients who voluntarily asked for SST with seven mental health professionals across Italy received a link to an online ad hoc survey, 1–3 weeks after the consultation, evaluating their experience. Study 1 found that the most frequent number of traditional psychotherapeutic (not intentionally SST) sessions was one (124 out of 476 clients (26%). Study 2 found that 44 out of 85 clients (52%) considered one session to be enough, as they felt better or much better and chose not to attend further sessions. Of those who asked for a second session (41 clients), 33 clients (80.5%) indicated that the first session was not enough and 8 clients (19.5%) wanted to address a new problem. These results converge with previous international studies and provide encouragement for the use of SST in both private and public psychological services to address the demand for timely mental health services in Italy. Further research is needed to support the efficacy of SST and to evaluate its cost‐effectiveness.
Biomimetic phospholipid polymers for suppressing adsorption of saliva proteins on dental hydroxyapatite substrate
Authors: Ishihara Kazuhiko , Kozaki Yoichiro , Inoue Yuuki , Fukazawa Kyoko 
Published: September 2020

AbstractTo prevent infectious diseases induced by the adhesion of microorganisms and their metabolic products to dental implants, saliva protein adsorption, which induces the plaque deposition to the intraoral substrates should be inhibited. We used a water‐soluble 2‐methacryloyloxyethyl phosphorylcholine (MPC) polymer to modify the surface of hydroxyapatite (HAp) substrate, the main component of dental implant surface. The MPC polymer containing a catechol group at the terminal of polymer chain and amino groups in the side chain was synthesized by mimicking the mussel adhesive protein. The MPC polymer containing 2% of the primary amino groups showed effective adhesion to the HAp substrate. Mucin, the dental plaque protein, adsorbs on the HAp surface; however, the MPC polymer modification could reduce this adsorption amount by more than 98% compared to the original HAp substrate surface. Thus, the treatment of the MPC polymer has potential to reduce oral infection due to plaque deposition.
Unsupported electrospun membrane for water desalination using direct contact membrane distillation
Authors: Jalloul Ghadeer , Hashem M. Hadi , Tehrani‐Bagha Ali Reza , Ahmad Mohammad N. , Abu Tarboush Belal J. 
Published: September 2020

AbstractIn this project, an unsupported electrospun poly(vinylidene fluoride)‐co‐hexafluoropropylene (PVDF‐HFP) membrane was used for water desalination using direct contact membrane distillation (DCMD). The membrane was electrospun using a laboratory‐scale machine with multiple nozzles that was developed in‐house. Critical process parameters, including the applied voltage and polymer concentration, were optimized to obtain bead‐free electrospun membranes with fiber diameters less than 300 nm. To improve the membrane thermal stability and performance, the selected electrospun membrane was heat‐pressed at 160°C. The untreated and heat‐pressed membranes were tested in a DCMD setup at different feed temperatures (60, 70, and 80°C) and feed flow rates (0.4, 0.6, and 0.8 L/min), while maintaining the permeate temperature and flow rate at 20°C and 0.2 L/min, respectively. The modified electrospun membrane exhibited a very high permeate flux (>37.5 kg/m2/h) and a salt rejection rate of 99.99% at a feed temperature of 70°C. The performance of the heat‐pressed unsupported PVDF‐HFP electrospun membrane was nearly identical to a commercially available polytetrafluoroethylene (PTFE) supported membrane. These promising results demonstrate that relatively low‐cost electrospun membranes can be easily produced and successfully used in DCMD to minimize the capital cost and increase the energy efficiency of the process.
Surface modification of TiO2 particles with 12‐hydroxy stearic acid and the effect of particle size on the mechanical and thermal properties of thermoplastic polyurethane urea elastomers
Authors: Wang Shuxiao , Wang Xiaoyan , Huang He 
Published: September 2020

AbstractThe efficient surface modification of titanium dioxide (TiO2) particles with different sizes was first carried out with “water only method” (Appl. Surf. Sci. 2018, 447, 664–672) developed in our group using 12‐hydroxy stearic acid (12‐HSA) as the modifier. The 12‐HSA‐modified TiO2 particles with different sizes were then used to explore their effect on the mechanical and thermal properties of a thermoplastic polyurethane urea (TPUU) elastomer with superior mechanical and thermal properties produced newly in our lab using nonsymmetric alicyclic diisocyanate and diamine. Orthogonal experimental results showed that the order of impact of each factor on the modification efficiency of TiO2 particles was: Temperature > time > modifier content. It was found that, in the nanometer (≤100 nm) range, smaller particles were more helpful to enhance the tensile strength of the TPUU elastomer, while larger ones to increase more significantly the elongation at break. Besides, the TiO2/polyurethane urea nanocomposites exhibited much better thermomechanical performance than the pristine TPUU elastomer, and the thermomechanical performance of the nanocomposites increased with decreasing particle size.
Thermal decomposition behavior of 3D printing filaments made of wood‐filled polylactic acid/starch blend
Authors: Sun Yufeng , Lee Danbee , Wang Yapeng , Li Suiliang , Ying Jilai , Liu Xinping , Xu Guangyin , Gwon Jaegyoung , Wu Qinglin 
Published: September 2020

AbstractDynamic thermogravimetric analysis under nitrogen environment was used to understand the thermal decomposition process of 3D printing filaments made of wood‐filled polylactic acid (PLA)/starch blend. The characteristic temperatures and apparent activation energy (AAE) of the filaments with various starch contents were calculated with well‐known kinetic models by Friedman, Flynn–Wall–Ozawa, Coats–Redfern, and Kissinger. With the increased starch content in the filament, the onset thermal decomposition temperatures of the filaments decreased gradually from 272.4 to 155.1°C. The thermal degradation degree became smaller, and the transitional temperature interval became larger with increased starch proportion. The AAE values of the three types of filaments with different starch ratios varied between 97 and 114 kJ/mol, depending on material composition and method of calculation. The four kinetics methods provide complementary techniques for analyzing thermal stability behavior of composite materials. The improved understanding of thermal decomposition behavior of PLA‐starch‐wood composites can help develop PLA/starch‐based filaments for 3D printing.
Benzoxazine monomers based on aromatic diamines and investigation of their polymerization by rheological and thermal methods
Authors: Sarychev Igor A. , Kireev Vyacheslav V. , Khmelnitskiy Vladimir V. , Vorobyeva Viktoria V. , Tupikov Anton S. , Haskov Maksim A. , Sirotin Igor S. 
Published: September 2020

AbstractIn the present article with the aim to find new polybenzoxazines with improved thermal properties, new benzoxazine monomers based on phenol and the following aromatic diamines were synthesized: 3,4′‐oxydianiline (P‐3,4′oda); o‐tolidine (P‐ot); m‐tolidine (P‐mt) and 4,4′‐(1,3‐phenylenedioxy)dianiline (P‐tper) and their comparison with the previously known benzoxazines based on 4,4′‐diaminodiphenylmethane (P‐ddm); 4,4′‐oxydianiline (P‐4,4′‐oda) and 2,2‐Bis[4‐(4‐aminophenoxy)phenyl]propane (P‐bapp). The dependence of the thermal and rheological characteristics on the structure of benzoxazine monomers based on various diamines was estimated and possible methods for their processing were identified. All the polybenzoxazines obtained in this work have high char yield and reduced flammability. It was found that the structure of the diamine can have a fundamental effect on both the rheological properties and heat resistance of polybenzoxazines. The benzoxazine monomers P‐ddm, P‐tper and P‐4,4′oda retain viscosity up to 1 Pa s. at 110°C for 2 h, the P‐tper monomer with a resorcinol bridge has about five times lower viscosity compared to the P‐bapp monomer with a bisphenol A bridge. Polybenzoxazines based on the monomers P‐ddm, P‐mt, P‐bapp and P‐tper show excellent thermal stability with a temperature of 10% weight loss above 400°C. In particular,Tgof P‐3,4′oda and P‐mt monomers is relatively high (202 and 239°C, respectively), while P‐ot's is unusually low (115°C), which may be caused by the specific effect of the substituents in the aromatic ring of the amine and their position.