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The thermodynamic incompatibility between the soft and hard segments of thermoplastic polyurethane (TPU) results in a microphase‐separated behavior and excellent mechanical properties. However, the effect of the chain extender on the degree of microphase separation (DMS) and the resultant mechanical properties of TPU have not been well studied because of the complex interactions between the soft and hard segments. Herein, hydroxyl‐terminated polybutadiene‐based TPUs(HTPB‐TPUs) without hydrogen bonding between the soft and hard segments are synthesized using hydroxyl‐terminated polybutadiene, toluene diisocyanate, and four different chain extenders, and the effect of the chain extender structure on DMS is analyzed experimentally using a combination of analytical techniques. Furthermore, the solubility parameters of the soft and hard segments, glass transition temperatures, and hydrogen‐bond density of the HTPB‐TPUs, are computed using all‐atom molecular dynamics simulations. The results clearly reveal that the chain extender significantly affects the DMS and thus the mechanical properties of HTPB‐TPUs. This study paves the way for studying the relationship between the structure and properties of TPU. [ABSTRACT FROM AUTHOR]

A systematic theoretical study was conducted on the triel bonds (TrB) within the BH3∙∙∙M(MDA)2 and C5H4BX∙∙∙M(MDA)2 (M = Ni, Pd, Pt, X = H, CN, F, CH3, NH2, MDA = enolated malondialdehyde) complexes, with BH3 and C5H4BX acting as the electron acceptors and the square-coordinated M(MDA)2 acting as the electron donor. The interaction energies of these systems range between −4.71 and −33.18 kcal/mol. The larger the transition metal center M, the greater the enhancement of the TrB, with σ–hole TrBs found to be stronger than π–hole TrBs. In the σ–hole TrB complex, an electron-withdrawing substituent on the C opposite to the B atom enhances the TrB, while an electron-donating substituent has little effect on the strength of TrB in the Pd and Pt complexes but enhances the TrB in the Ni-containing complexes. The van der Waals interaction plays an important role in stabilizing these binary systems, and its contribution diminishes with increasing M size. The orbital effect within these systems is largely due to charge transfer from the dz2 orbital of M into the empty pz orbital of B. [ABSTRACT FROM AUTHOR]

The tetrel bond between PhXF2Y(TF3) (T = C and Si; X = Cl, Br, and I; Y = F and Cl) and the electron donor MCN (M = Li and Na) was investigated at the M06-2X/aug-cc-pVDZ level of theory. As the electronegativity of the halogen atom X increases, the strength of the tetrel bond also increases, but as the electronegativity of the halogen atom Y increases, the strength of the tetrel bond decreases. The magnitude of the interaction energy in most –CF3 complexes was found to be less than 10 kcal/mol, but to exceed 11 kcal/mol for PhClF2Cl(CF3)⋯NCNa. The tetrel bond is greatly enhanced when the –SiF3 group interacts with LiCN or NaCN, with the largest interaction energy approaching 100 kcal/mol and displaying a covalent Si⋯N interaction. Along with this enhancement, the Si⋯N distance was found to be less than the X–Si bond length, the –SiF3 group to be closer to the N atom, and in most –SiF3 systems, the X–Si–F angle to be less than 90°; the –SiF3 group therefore undergoes inversion and complete transfer in some systems. [ABSTRACT FROM AUTHOR]

The tetrel bond (TB) between 1,2-benzisothiazol-3-one-2-TF3-1,1-dioxide (T = C, Si) and the O atom of pyridine-1-oxide (PO) and its derivatives (PO-X, X = H, NO2, CN, F, CH3, OH, OCH3, NH2, and Li) is examined by quantum chemical means. The Si∙∙∙O TB is quite strong, with interaction energies approaching a maximum of nearly 70 kcal/mol, while the C∙∙∙O TB is an order of magnitude weaker, with interaction energies between 2.0 and 2.6 kcal/mol. An electron-withdrawing substituent on the Lewis base weakens this TB, while an electron-donating group has the opposite effect. The SiF3 group transfers roughly halfway between the N of the acid and the O of the base without the aid of cooperative effects from a third entity. [ABSTRACT FROM AUTHOR]

The π-hole triel bond formed by (BH)2(NHC)2 (NHC denotes nitrogen-heterocyclic carbene) and TrPhX2 (Tr = B, Al, and Ga; X = F, Cl, Br, CH3, and OH) was investigated computationally, with the B=B bond in (BH)2(NHC)2 being the electron donor. A large interaction energy ensures that the complex is quite stable. When the substituent X in the electron acceptor is fixed, the magnitude of the interaction energy varies with the identity of the Tr atom. When Tr is Al or Ga, the interaction energy is stronger than when it is B. With an increase in the electron-withdrawing ability of the substituents, the interaction energy shows distinct changes. When Tr is B or Al, the interaction energy varies as TrPhBr2 > TrPhCl2 > TrPhF2, which is different from the order of their positive electrostatic potentials. When Tr = Ga, the interaction energy hardly changes with an increase in the electronegativity of the halogen atoms. For CH3 and OH substitution, larger interaction energies were obtained, with the interaction energy for the OH substituent being the largest. The main interactions in these systems are a triel bond and an X· ·H hydrogen bond. When the substituents are fixed, the interaction energy of the triel bond increases in the order AlPhX2 < GaPhX2 < BPhX2, which is different from the order of the positive electrostatic potentials on the Tr atom in TrPhX2. When X is a halogen atom, the interaction energy of the triel bond decreases in the order Br > Cl > F, which is opposite to the trend for the positive electrostatic potentials on Tr in TrPhX2. In most complexes, the interaction energy for the hydrogen bond is less than that for the triel bond; there is no hydrogen bond in the methyl-substituted complex. In general, the interaction energy of the hydrogen bonds increases with an increase in the electronegativity of the halogen atoms. [ABSTRACT FROM AUTHOR]

Vibration and noise-reduction materials are indispensable in various fields. Polyurethane (PU)-based damping materials can dissipate the external mechanical and acoustic energy through molecular chain movements to mitigate the adverse effects of vibrations and noise. In this study, PU-based damping composites were obtained by compositing PU rubber prepared using 3-methyltetrahydrofuran/tetrahydrofuran copolyether glycol, 4,4′-diphenylmethane diisocyanate, and trimethylolpropane monoallyl ether as raw materials with hindered phenol, viz., and 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)proponyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (AO-80). Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and tensile tests were conducted to evaluate the properties of the resulting composites. The glass transition temperature of the composite increased from −40 to −23 °C, and the tan δMax of the PU rubber increased by 81%, from 0.86 to 1.56 when 30 phr of AO-80 was added. This study provides a new platform for the design and preparation of damping materials for industrial applications and daily life. [ABSTRACT FROM AUTHOR]

Heat pipes (HPs) are gaining increasing popularity in the propulsion motors of transportation electrification due to their remarkable thermal properties. However, the inclination angle affects the HP thermal performance and, thus, results in temperature nonuniformity, which may generate unbalanced thermal stress on the motor. Such an issue has received less attention to date and requires corresponding solutions. This article performs an experimental investigation on motor temperature nonuniformity with HPs and further proposes an improved structure to address this problem. A specimen based on a stator-winding assembly with HPs is prepared and a dedicated experimental platform is established. Then, the temperature distribution across the specimen is studied, followed by an evaluation of the effects of current density and wind velocity. To compensate for the degradation of HP thermal performance, an improved structure with enlarged fins is proposed, and the equilibrium point is determined by fitting and comparing the obtained temperature data. Finally, the proposed structure is verified by the comparison between the original and improved specimens. The experimental results show that the non-uniform temperature distribution is significantly improved, with the temperature range and standard deviation reduced by 42% and 44.3%, respectively. [ABSTRACT FROM AUTHOR]

The paper presents a novel waterflooding technique, coupling cyclic high-pressure water slug injection with an asynchronous injection and production procedure, to address the inefficient development of low-permeability oil reservoir in Shengli Oilfield, a pilot test with 5-spot well pattern. Based on the first-hand data from the pilot test, the reservoir model is established. With an in-depth understanding of the mechanism of the novel waterflooding technique, different simulation schemes are employed to screen the best scheme to finely investigate the historical performance of the pilot test. The production characteristics of the pilot test are both qualitatively and quantitatively investigated. It is found that the novel waterflooding technique can provide pressure support within a short period. And the formation around the injector is significantly activated and deformed. Once passing the short stage of the small elastic deformation, the reservoir immediately goes through the dilation deformation accompanied with the opening of microfractures so that the reservoir properties are significantly improved, which leads to better reservoir performance. With the multicyclic dilation-recompaction geomechanical model, the impact of pressure cyclic evolution on the reservoir properties and performance under the novel waterflooding mode of cyclic high-pressure water slug injection is taken into consideration. The historical data of the pilot test is well matched. In the study, a high-precision simulation scheme for the novel waterflooding technique in low-permeability reservoirs is proposed, which provides significant technical support for further optimization of the pilot test and large-scale application of the novel waterflooding technique. [ABSTRACT FROM AUTHOR]

CO2 geological sequestration in shale is a promising method to mitigate global warming caused by greenhouse gas emissions as well as to enhance the gas recovery to some degree, which effectively addresses the problems related to energy demand and climate change. With the data from the New Albany Shale in the Illinois Basin in the United States, the CMG-GEM simulator is applied to establish a numerical model to evaluate the feasibility of CO2 sequestration in shale gas reservoirs with potential enhanced gas recovery (EGR). To represent the matrix, natural fractures, and hydraulic fractures in shale gas reservoirs, a multicontinua porous medium model will be developed. Darcy's and Forchheimer's models and desorption-adsorption models with a mixing rule will be incorporated into the multicontinua numerical model to depict the three-stage flow mechanism, including convective gas flow mainly in fractures, dispersive gas transport in macropores, and CH4-CO2 competitive sorption phenomenon in micropores. With the established shale reservoir model, different CO2 injection schemes (continuous injection vs. pulse injection) for CO2 sequestration in shale gas reservoirs are investigated. Meanwhile, a sensitivity analysis of the reservoir permeability between the hydraulic fractures of production and injection wells is conducted to quantify its influence on reservoir performance. The permeability multipliers are 10, 100, and 1,000 for the sensitivity study. The results indicate that CO2 can be effectively sequestered in shale reservoirs. But the EGR of both injection schemes does not perform well as expected. In the field application, it is necessary to take the efficiency of supplemental energy utilization, the CO2 sequestration ratio, and the effect of injected CO2 on the purity of produced methane into consideration to design an optimal execution plan. The case with a permeability multiplier of 1,000 meets the demand for both CO2 sequestration and EGR, which indicates that a moderate secondary stimulation zone needs to be formed between the primary hydraulic fractures of injection and production wells to facilitate the efficient energy transfer between interwell as well as to prevent CO2 from channeling. To meet the demand for CO2 sequestration in shale gas reservoirs with EGR, advanced and effective fracking is essential. [ABSTRACT FROM AUTHOR]

One of the goals of bone tissue engineering is to mimic native ECM in architecture and function, creating scaffolds with excellent biocompatibility, osteoinductive ability and mechanical properties. The aim of this study was to fabricate nanofibrous matrices by electrospinning a blend of poly (L-lactic-co-glycolic acid) (PLGA), hydroxyapatite (HA), and grapheme oxide (GO) as a favourable platform for bone tissue engineering. The morphology, biocompatibility, mechanical properties, and biological activity of all nanofibrous matrices were compared. The data indicate that the hydrophilicity and protein adsorption rate of the fabricated matrices were significantly increased by blending with a small amount of HA and GO. Furthermore, GO significantly boosted the tensile strength of the nanofibrous matrices, and the PLGA/GO/HA nanofibrous matrices can serve as mechanically stable scaffolds for cell growth. For further test in vitro, MC3T3-E1 cells were cultured on the PLGA/HA/GO nanofbrous matrices to observe various cellular activities and cell mineralization. The results indicated that the PLGA/GO/HA nanofibrous matrices significantly enhanced adhesion, and proliferation in MCET3-E1 cells and functionally promoted alkaline phosphatase (ALP) activity, the osteogenesis-related gene expression and mineral deposition. Therefore, the PLGA/HA/GO composite nanofibres are excellent and versatile scaffolds for applications in bone tissue regeneration. [ABSTRACT FROM AUTHOR]

Background: With radiotherapy (RT) alone, the five-year overall survival (OS) rate for advanced nasopharyngeal carcinoma (NPC) can only reach 40%, the ratio of distant metastasis (DM) is 36-40%. This meta-analysis was performed to compare the clinical efficacy of concurrent chemoradiotherapy (CCRT) with RT alone in the treatment of locoregionally advanced NPC.Methods: The related literature were retrieved and reviewed by two independent investigators from the followed electronic databases: Review manager 5.3 software (Cochrane Collaboration, London, United Kingdom) was applied for statistical analysis.Results: A total of 16 trials with 2576 patients were recruited according to the criterion. The odds ratios of 3 and 5 years OS was 0.53 (95% confidence interval [95% CI]: 0.44-0.64) and 0.58 (95% CI: 0.48-0.71), which confirmed the significant improvement of CCRT compared with RT alone (P < 0.001). CCRT also reduced the risk of locoregional control failure and DM in locoregionally advanced NPC patients.Conclusions: The results suggested that CCRT was more beneficial when compared with RT alone in locoregionally advanced NPC patients. Further study is needed to perform to confirm this effect. [ABSTRACT FROM AUTHOR]

Anaerobically digested piggery wastewater (ADPW) draws increasing attention due to the high nitrogen and carbon level. In this study, four parallel lab-scale anoxic-oxic membrane bioreactors were applied to treat ADPW with the hydraulic retention time (HRT) of 75, 60, 45 and 30 h, respectively. Reactor performance and membrane fouling mechanisms also have been systematically evaluated. The results demonstrated a decline in chemical oxygen demand and total nitrogen biodegradation (from 65.8 ± 2.5% and 62.2 ± 5.5% to 38.6 ± 3.6% and 26.2 ± 5.7%, respectively) and a rise in membrane resistance (from 37.34 × 1012 m−1 to 51.69 × 1012 m−1) as the HRT decreased. The decline of HRT didn't affect the functional group types of cake layer extracellular polymeric substances (EPS) and tightly bound EPS (TB-EPS) of activated sludge, but led to the increased concentrations of protein (PN) and polysaccharide (PS) in loosely bound EPS (LB-EPS) and soluble microbial products (SMP) of activated sludge and a decreased PN/PS ratio in SMP. These changes in SMP and EPS accelerated the formation of cake layer and aggravated the membrane fouling. Proteobacteria and Bacteroidetes were the predominant phyla on membrane surface. The abundant Proteobacteria in the reactor with longer HRTs was beneficial to mitigate membrane fouling while the relative abundance of Bacteroidetes remained stable in all reactors. The enrichment of Thauera was the primary reason for membrane fouling at genus level in the reactors. This study provides scientific insights on the practical application of membrane bioreactors in terms of membrane fouling control. ga1 • Reducing HRT led to a decline of COD and TN removal efficiency. • Longer HRT improved membrane permeability and mitigated the membrane fouling. • Decreased PN SMP /PS SMP ratio and increased LB-EPS AS aggravated membrane fouling. • Abundant Proteobacteria was helpful to mitigate membrane fouling. [ABSTRACT FROM AUTHOR]

• Mn 3 (PO 4) 2 nanoflakes are firstly explored as the efficient polysulfide inhibitor in Li-S battery. • The Mn 3 (PO 4) 2 /rGO composites can effectively suppress the polysulfide shuttle. • The S@Mn 3 (PO 4) 2 /rGO composites show the enhanced electrochemical performances. The development of Lithium surfur batteries (LSBs) are beset with tenacious issues including the insulating property of the sulfur element and the dissolution of the reaction intermediate products into electrolyte, which result in low S utilization and poor battery cycling performances. In this work, we exploit metal phosphate as the S host for suppressing the sulfur dissolving and accelerating the polysulfide conversion, and firstly construct the S@Mn 3 (PO 4) 2 /rGO composites through an in-situ solution growth followed by S impregnation route. More importantly, the geometric compatibility of Mn 3 (PO 4) 2 nanoflakes and rGO nanosheet endows such S@Mn 3 (PO 4) 2 /rGO composites with high electrical conductivity and excellent mechanical durability. As evidenced by the electrochemical performances in LSB, the S@Mn 3 (PO 4) 2 /rGO cathode shows discharge capacities of 863 mA g−1 at 0.2 C after 100 cycles and 658 mAh g−1 after 470 cycles at 1.0 C with high Coulumbic efficiency of nearly 100%; more impressively, it delivers a high capacity of 407 mAh g−1 ever at 5.0 C rate during rate capability testing. Our research on the construction of S@Mn 3 (PO 4) 2 /rGO composites provides new insight and opportunitie to develop advanced LSBs with highly efficient inhibitors for trapping polysulfides and accelerating their conversion. [ABSTRACT FROM AUTHOR]

The main issues of lithium–sulfur (Li–S) batteries, including the insulating properties of electrode materials and the dissolution of lithium polysulfides into electrolytes, hinder their further development. Encapsulating S with a conductive agent is considered as an effective way to address these issues. The electrical conductivity of the electrode is substantially improved by the addition of a conductive agent. Furthermore, the polysulfide dissolution is also effectively suppressed by the physical/chemical confinement of the additives. An exploration of new encapsulation agents for the S cathode–hierarchical porous carbon derived from a peanut hull is reported. Such structures comprise the 3D interconnected network carbon and abundant meso/micropores, which significantly improve the electronic conductivity and effectively suppress the polysulfide dissolution. The high S loading, long lifespan, and great rate capability empower such a strategy to be an effective way to push the Li–S battery to further development. An exploration of a new encapsulation agent for S cathode is reported, hierarchical porous carbon (HPC) derived from peanut hull, which could significantly improve the electronic conductivity and effectively suppress the polysulfide dissolution. The high S loading, the long lifespan, and great rate capability empower such a strategy to be an effective way to push the Li–S batteries forward in development. [ABSTRACT FROM AUTHOR]

Sodium ion battery (SIB) has been recognized as the successor to lithium ion battery (LIB) owing to its inherit feature of low cost and abundant resource. The commercial graphite anodes in LIB have been demonstrated unsuitable to accommodate Na+ due to the larger ionic radius than Li+. In this work, FeSe nanoparticles embedded in N-doped carbon (denoted as FeSe/N–C) are produced by one-step solid-phase process and explored as the potential anode candidate in SIB. Such composites exhibit high conductivity and special structural durability which provide good charge transport kinetics. As expected, the FeSe/N–C electrode displays high specific capacity, excellent rate performance and ultra-stable long-term cycling stability: it delivers a reversible capacity of 468.5 mAh g−1 at 0.5C rate, and 333.9 mAh g−1 for 800th cycle at 2.0C rate; more impressively, it exhibits a 235.9 mAh g−1 at 5.0C rate during the rate capability testing. This simple synthesis procedure may open up a way to engineer other metal selenide with carbonaceous modification agents for Na+-storage considering the cost-efficient and easy-scalability. Image 1 • A new promising anode for sodium ion battery is explored. • FeSe nanoparticles embedded in N-doping carbon are facilely fabricated for the first time. • These FeSe/N–C composites present excellent Na+-storage performances. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to propose a novel and effective throat swab collection method for coronavirus disease 2019 (COVID-19)., Methods: The subjects were randomly divided into two groups. The subjects were asked to open their mouth to make "ah" sound (traditional method) or simulate yawn (improved method) for throat swab collection. The usage of tongue depressor, collection time, adverse reactions and subjective discomfort (VAS score) were compared. The collection time, comprehensive indicators of adverse reactions and VAS score were also compared among three collectors., Results: The tongue depressor was less used in the improved group (χ 2 = 40.186, P < 0.01). The average collection time of the traditional group was 5.44 ± 2.97 and that of the improved group was 4.00 ± 2.31 (P < 0.01). The subjects in the improved group had fewer and milder adverse reactions. The VAS score of subjects in the improved group was lower than that in the traditional group (P < 0.01). Among different collectors, the collection time, comprehensive indicators of adverse reactions and VAS were the same as the overall trend., Conclusion: Simulating yawn is a safer and faster throat swab collection method., (Copyright © 2021 Elsevier Inc. All rights reserved.)