Modulating Co-Co bonds average length in Co_(0.85)Se_(1-x)S_(x) to enhance conversion reaction for potassium storage

While alloying transition metal chalcogenides(TMCs)with other chalcogen elements can effectively improve their conductivity and electrochemical properties,the optimal alloying content is still uncertain.In this study,we study the influence of dopant concentration on the chemical bonds in TMC and reveal the associated stepwise conversion reaction mechanism for potassium ion storage.According to density function theory calculations,appropriate S-doping in Co0.85Se(Co_(0.85)Se_(1-x)S_(x))can reduce the average length of Co-Co bonds because of the electronegativity variation,which is thermodynamically favourable to the phase transition reactions.The optimal Se/S ratio(x=0.12)for the conductivity has been obtained from experimental results.When assembled as an anode in potassium-ion batteries(PIBs),the sample with optimized Se/S ratio exhibits extraordinary electrochemical performance.The rate performance(229.2 mA h g^(-1)at 10 A g^(-1))is superior to the state-of-the-art results.When assembled with Prussian blue(PB)as a cathode,the pouch cell exhibits excellent performance,demonstrating its great potential for applications.Moreover,the stepwise K+storage mechanism caused by the coexistence of S and Se is revealed by in-situ X-ray diffraction and ex-situ transmission electron microscopy techniques.Hence,this work not only provides an effective strategy to enhance the electrochemical performance of transition metal chalcogenides but also reveals the underlying mechanism for the construction of advanced electrode materials.

Genetic Analysis of Two Novel GPI Variants Disrupting H Bonds and Localization Characteristics of 55 Gene Variants Associated with Glucose-6-phosphate Isomerase Deficiency

Objective:Glucose-6-phosphate isomerase(GPI)deficiency is a rare hereditary nonspherocytic hemolytic anemia caused by GPI gene variants.This disorder exhibits wide heterogeneity in its clinical manifestations and molecular characteristics,often posing challenges for precise diagnoses using conventional methods.To this end,this study aimed to identify the novel variants responsible for GPI deficiency in a Chinese family.Methods:The clinical manifestations of the patient were summarized and analyzed for GPI deficiency phenotype diagnosis.Novel compound heterozygous variants of the GPI gene,c.174C>A(p.Asn58Lys)and c.1538G>T(p.Trp513Leu),were identified using whole-exome and Sanger sequencing.The AlphaFold program and Chimera software were used to analyze the effects of compound heterozygous variants on GPI structure.Results:By characterizing 53 GPI missense/nonsense variants from previous literature and two novel missense variants identified in this study,we found that most variants were located in exons 3,4,12,and 18,with a few localized in exons 8,9,and 14.This study identified novel compound heterozygous variants associated with GPI deficiency.These pathogenic variants disrupt hydrogen bonds formed by highly conserved GPI amino acids.Conclusion:Early family-based sequencing analyses,especially for patients with congenital anemia,can help increase diagnostic accuracy for GPI deficiency,improve child healthcare,and enable genetic counseling.

Estimating heat capacities of liquid organic compounds based on elements and chemical bonds contribution

Molecular property depends on the property, the number of the elements, and the interaction between elements(such as chemical bonds). Based on the above-mentioned idea, two methods to estimate the isobaric heat capacity of liquids organic compounds were developed. Ten elements groups and 32 chemical bond groups were defined by considering the structure of organic compounds. The group contribution values and correlation parameters were regressed by the ridge regression method with the experiment data of 1137 compounds. The heat capacity can be calculated by summating the contributions of the elements and chemical bond groups. The two methods were compared with existing group contribution methods, such as Chickos, Zabransky-Ruzicka, and Zdenka Kolska. The results show that those new estimation methods' overall average relative deviations were 5.81% and 5.71%, which were lower than the other three methods. Those methods were more straightforward in compound splitting.Those new methods can be used to estimate the liquid heat capacity of silicon-containing compounds,which the other three methods cannot estimate. The new methods are more accessible, broader, and more accurate. Therefore, this research has important scientific significance and vast application prospects.

Functional zirconium phosphate nanosheets enabled transfer hydrogenolysis of aromatic ether bonds over a low usage of Ru nanocatalysts

Catalytic hydrogenolysis of aromatic ether bonds is a highly promising strategy for upgrading lignin into small-molecule chemicals,which relies on developing innovative heterogeneous catalysts with high activity.Herein,we designed porous zirconium phosphate nanosheet-supported Ru nanocatalysts(Ru/ZrPsheet)as the heterogeneous catalyst by a process combining ball milling and molten-salt(KNO_(3)).Very interestingly,the fabricated Ru/ZrPsheetshowed good catalytic performance on the transfer hydrogenolysis of various types of aromatic ether bonds contained in lignin,i.e.,4-O-5,a-O-4,β-O-4,and aryl-O-CH3,over a low Ru usage(<0.5 mol%)without using any acidic/basic additive.Detailed investigations indicated that the properties of Ru and the support were indispensable.The excellent activity of Ru/ZZrPsheetoriginated from the strong acidity and basicity of ZrPsheetand the higher electron density of metallic Ru0as well as the nanosheet structure of ZrPsheet.

A Self-Healing and Nonflammable Cross-Linked Network Polymer Electrolyte with the Combination of Hydrogen Bonds and Dynamic Disulfide Bonds for Lithium Metal Batteries

The self-healing solid polymer electrolytes(SHSPEs)can spontaneously eliminate mechanical damages or micro-cracks generated during the assembly or operation of lithium-ion batteries(LIBs),significantly improving cycling performance and extending service life of LIBs.Here,we report a novel cross-linked network SHSPE(PDDP)containing hydrogen bonds and dynamic disulfide bonds with excellent self-healing properties and nonflammability.The combination of hydrogen bonding between urea groups and the metathesis reaction of dynamic disulfide bonds endows PDDP with rapid self-healing capacity at 28°C without external stimulation.Furthermore,the addition of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(EMIMTFSI)improves the ionic conductivity(1.13×10^(−4)S cm^(−1)at 28°C)and non-flammability of PDDP.The assembled Li/PDDP/LiFePO_(4)cell exhibits excellent cycling performance with a discharge capacity of 137 mA h g^(−1)after 300 cycles at 0.2 C.More importantly,the self-healed PDDP can recover almost the same ionic conductivity and cycling performance as the original PDDP.

Ni-catalyzed carbon–carbon bonds cleavage of mixed polyolefin plastics waste

The inert carbon–carbon(C–C) bonds cleavage is a main bottleneck in the chemical upcycling of recalcitrant polyolefin plastics waste. Here we develop an efficient strategy to catalyze the complete cleavage of C–C bonds in mixed polyolefin plastics over non-noble metal catalysts under mild conditions. The nickelbased catalyst involving Ni_(2)Al_(3) phase enables the direct transformation of mixed polyolefin plastics into natural gas, and the gas carbon yield reaches up to 89.6%. Reaction pathway investigation reveals that natural gas comes from the stepwise catalytic cleavage of C–C bonds in polypropylene, and the catalyst prefers catalytic cleavage of terminal C–C bond in the side-chain with the low energy barrier.Additionally, our developed approach is evaluated by the technical economic analysis for an economically competitive production process.

KVPO_(4)F/carbon nanocomposite with highly accessible active sites and robust chemical bonds for advanced potassium-ion batteries

KVPO_(4)F(KVPF)has been extensively investigated as the potential cathode material for potassium-ion batteries(PIBs)owing to its high theoretical capacity,superior operating voltage,and three-dimensional Kt conduction pathway.Nevertheless,the electrochemical behavior of KVPF is limited by the inherent poor electronic conductivity of the phosphate framework and unstable electrode/electrolyte interface.To address the above issues,this work proposes an infiltration-calcination method to confine the in-situ grown KVPF into the mesoporous carbon CMK-3(denoted KVPF@CMK-3).The assembled KVPF@CMK-3 nanocomposite features three-dimensional interconnected carbon channels,which not only offer abundant active sites and significantly accelerate K t/electron transport,but also prevent the growth of KVPF nanoparticle agglomerates,hence stabilizing the structure of the material.Additionally,V–F–C bonds are created at the interface of KVPF and CMK-3,which reduce the loss of F and stabilize the electrode interface.Thus,when tested as a cathode material for PIBs,the KVPF@CMK-3 nanocomposite delivers superior reversible capacitiy(103.2 mAh g^(-1) at 0.2 C),outstanding rate performance(90.1 mAh g^(-1) at 20 C),and steady cycling performance(92.2 mAh g^(-1) at 10 C and with the retention of 88.2%after 500 cycles).Moreover,its potassium storage mechanism is further examined by ex-situ XRD and ex-situ XPS techniques.The above synthetic strategy demonstrates the potential of KVPF@CMK-3 to be applied as the cathode for PIBs.

Improving the Heat Resistance ofβ-1,4 Glucanase by Introducing Disulfide Bonds

Each possible pair of residues inβ-1,4 glucanase for disulfide formation was assessed using online websites,and four pairs L28C-S256C,Q41C-P278C,S122C-N163C and A184C-A215C were selected.Accordingly,four recombinant plasmids pET28a(+)EccslH28,pET28a(+)EccslH41,pET28a(+)EccslH122 and pET28a(+)EccslH184 were prepared and transformed into E.coli to express the recombinant enzymes.Then analysis on enzymatic properties showed that T50 of the recombinant enzymes was increased from 10 min for EccslHt2 to 90 min for EccslH28 and 40 min for EccslH41 at 70℃,while their optimum pH value and pH stability were not affected,which proved that the introduction of disulfide bond improved the thermal stability ofβ-1,4 glucanase.

Reconstruction of broken Si–O–Si bonds in iron ore tailings (IOTs) in concrete

This paper reports a study on the reconstruction of broken Si O Si bonds in iron ore tailings (IOTs) in concrete. Limestone and IOTs were used to investigate the influence of different types of coarse aggregates on the compressive strengths of concrete samples. The dif- ferences in interfacial transition zones (ITZs) between aggregate and paste were analyzed by scanning electron microscopy (SEM) and ener- gy-dispersive spectroscopy (EDS). Meanwhile, X-ray diffraction (XRD) and infrared spectroscopy (IR) were used to study microscopic changes in limestone and IOTs powders in a simple alkaline environment that simulated cement. The results show that the compressive strengths of IOTs concrete or paste are higher than those of limestone concrete or paste under identical conditions. The Ca/Si atom ratios in the ITZs of IOTs con- crete samples are lower than those of limestone concrete;the diffraction peak of the calcium silicate phase at 2θ = 29.5°, as well as the bands of Si O bonds shifting to lower wavenumbers, indicates reconstruction of the broken Si-O-Si bonds on the surfaces of IOTs with Ca(OH)2.

Diffusive-stochastic-viscoelastic model on specific adhesion of viscoelastic solids via molecular bonds

A diffusive-stochastic-viscoelastic model is proposed for the specific adhesion of viscoelastic solids via stochastically formed molecular bonds. In this model, we assumed that molecular level behaviours, including the diffusion of mobile adhesion molecules and stochastic reaction between adhesion molecules and binding sites, obey the Markovian stochastic processes, while mesoscopic deformations of the viscoelastic media are governed by continuum mechanics. Through Monte Carlo simulations of this model, we systematically investigated how the competition between time scales of molecular diffusion, reaction, and deformation creep of the solids may influence the lifetime and dynamic strength of the adhesion. We revealed that there exists an optimal characteristic time of molecule diffusion corresponding to the longest lifetime and largest adhesion strength, which is in good agreement with experimental observed characteristic time scales of molecular diffusion in cell membranes. In addition, we identified that the media viscosity can significantly increase the lifetime and dynamic strength, since the deformation creep and stress relaxation can effectively reduce the concentration of interfacial stress and increases the rebinding probability of molecular bonds.

Syntheses and Crystal Structures of Two 3D Zinc(II) Compounds Involving Coordination and Hydrogen Bonds

Two zinc（Ⅱ） compounds, [Zn（L）（H2O）2]n 1 and [Zn（4,4＇-bpy）（H2O）4]（L） 2 （H2L = trans,trans-1,3 butadiene 1,4-dicarboxylic acid）, were synthesized by hydrothermal methods and characterized by single-crystal X-ray diffraction analyses. Compound 1 crystallizes in monoclinic, space group C2/c with a=15.4970（16）, b = 5.4976（6）, c = 10.7113（12） A, β=96.298（6）°, C6H8O6Zn, Mr = 241.50, V = 907.06（17） A^3, Z = 4, D, = 1.768 g/cm^3, F（000） = 488,μ = 2.703 mm^-1, S = 1.060, the final R = 0.0256 and wR = 0.0660 for 968 observed reflections with Ⅰ 〉 2σ（Ⅰ）. Compound 2 crystallizes in triclinic, space group P1^- with a = 6.915（2）, b = 7.166（2）, c = 10.363（3） A, α = 73.250（4）, β = 84.429（4）, γ = 61.605（3）°, C16H2ON2O8Zn, Mr = 433.70, V = 432.1 （2） A^3, Z = 1, D, = 1.667 g/cm^3, F（000） = 224 and μ= 1.471 mm^-1, S = 1.118, the final R = 0.0486 and wR = 0.1077 for 1352 observed reflections with Ⅰ〉 2σ（Ⅰ）. Upon using the assembly strategy of combination of coordination polymer chains with intermolecular hydrogen bonds, three-dimensional frameworks of complexes 1 and 2 were formed.

Price distortions and municipal bonds premiums:evidence from Switzerland

This study examines the pricing of municipal bonds before and after a currency shock in Switzerland.Two approaches are used to decompose the municipal to treasuries bond spreads into liquidity,maturity,and default risk premiums.The first approach is the model of the cross-sectional instrumental variables,and the second approach is the model of the instrumental variables with panel data.This study examines the composition of spreads for both approaches,in three scenarios:before,throughout,and after the currency shock.The study performed Durbin-Wu-Hausman tests for each decisive model to verify endogeneity issues,including the Lagrangian Multiplier test,the Cragg-Donald Wald F statistic to confirm the relationship of instrumental and endogenous variables,and the structural break test(Bai-Perron test)to determine the existence of structural breaks in bond distortions.This study finds that the currency price distortions of the Swiss franc in January 2015 made long-run changes in the composition of the municipal bond spreads.This research contributes to the understanding of municipal bond pricing by showing that default risk accounts for a large portion of the municipal bond spread,while maturity risk plays a lesser role.According to our empirical findings,unexpected large currency price shocks may have long-term implications on the municipal bond spreads.

Portfolio optimization of credit risky bonds: a semi-Markov process approach

This article presents a semi-Markov process based approach to optimally select a portfolio consisting of credit risky bonds.The criteria to optimize the credit portfolio is based on l_(∞)-norm risk measure and the proposed optimization model is formulated as a linear programming problem.The input parameters to the optimization model are rate of returns of bonds which are obtained using credit ratings assuming that credit ratings of bonds follow a semi-Markov process.Modeling credit ratings by semi-Markov processes has several advantages over Markov chain models,i.e.,it addresses the ageing effect present in the credit rating dynamics.The transition probability matrices generated by semi-Markov process and initial credit ratings are used to generate rate of returns of bonds.The empirical performance of the proposed model is analyzed using the real data.Further,comparison of the proposed approach with the Markov chain approach is performed by obtaining the efficient frontiers for the two models.

The Pricing of Convertible Bonds with a Call Provision

This paper deals with the pricing of convertible bond with call provision based on the traditional B-S formula. By applying the principle of no arbitrage, the partial differential equation for the bond is established with identified boundary conditions, which solution results in the closed form of the pricing formula.

Ab initio path-integral molecular dynamics and the quantum nature of hydrogen bonds

The hydrogen bond （HB） is an important type of intermolecular interaction, which is generally weak, ubiquitous, and essential to life on earth. The small mass of hydrogen means that many properties of HBs are quantum mechanical in nature. In recent years, because of the development of computer simulation methods and computational power, the influence of nuclear quantum effects （NQEs） on the structural and energetic properties of some hydrogen bonded systems has been intensively studied. Here, we present a review of these studies by focussing on the explanation of the principles underlying the simulation methods, i.e., the ab initio path-integral molecular dynamics. Its extension in combination with the thermodynamic integration method for the calculation of free energies will also be introduced. We use two examples to show how this influence of NQEs in realistic systems is simulated in practice.

Helium Plasma Damage of Low-k Carbon Doped Silica Film:the Effect of Si Dangling Bonds on the Dielectric Constant

The low-k carbon doped silica film has been modified by radio frequency helium plasma at 5 Pa pressure and 80 W power with subsequent XPS, FTIR and optical emission spec- troscopy analysis. XPS data indicate that helium ions have broken Si-C bonds, leading to Si-C scission with C（1s） lost seriously. The Si（2p）, O（ls）, peak obviously shifted to higher binding en- ergies, indicating an increasingly oxidized Si（2p）. FTIR data also show that the silanol formation increased with longer exposure time up to a week. Contrarily, the CHa stretch, Si-C stretching bond and the ratio of the Si-O-Si cage and Si-O-Si network peak sharply decreased upon exposure to helium plasma. The OES result indicates that monovalent helium ions in plasma play a key role in damaging carbon doped silica film. So it can be concluded that the monovalent helium ions besides VUV photons can break the weak Si-C bonds to create Si dangling bonds and free methyl radicals, and the latter easily reacts with O_2 from the atmosphere to generate CO_2 and H_2O. The bonds change is due to the Si dangling bonds combining with H_2O, thereby, increasing the dielectric constant k value.

EFEECT OF METALLIC CATIONS ON Si-O BONDS IN SILICATES

The effect of metallic cations on the Si-O(br) bond and the Si-O(ter) bond was studied with CNDO/2 MO calculations. The characteristics of them were discussed, which were found to vary with the bonding and coordi nation situation of oxygen as well as the effect of metallic cations on oxygen. The conclusions obtained may be well used in the fields of mineralogy, geochemistry, silicate materials, pyrometallurgy and so on.

B-C-N Compounds with Mixed Hybridization of sp^(2)-Like and sp^(3)-Like Bonds

We perform first-principles calculations of the structural and electronic properties of hypothetical bc6-BC_(4)N and N-substituted bc6-BC4N,which are derived from a body-center-cubic carbon structure.Our calculations show that the former is a semiconductor with an indirect band gap of 0.91 eV and the latter is metallic.The calculated bond length,bond population,and charge density of N-substituted bc6-BC4N indicate that one C-N bond has been broken after N-substitution,which means that the structure contains a mixed hybridization of sp^(2)-like and sp^(3)-1ike bonds.At the pressure above 100 GPa,the structure changes to a pure sp^(3)-like hybridization.

The Volatility of High-Yield Bonds Using Mixed Data Sampling Methods

It is well known that economic policy uncertainty prompts the volatility of the high-yield bond market.However,the correlation between economic policy uncertainty and volatility of high-yield bonds is still not clear.In this paper,we employ GARCH-MIDAS models to investigate their correlation with US economic policy uncertainty index and S&P high-yield bond index.The empirical studies show that mixed volatility models can effectively capture the realized volatility of high-yield bonds,and economic policy uncertainty and macroeconomic factors have significant effects on the long-term component of high-yield bonds volatility.

Combining Hydraulic and Phosphate Bonds to Improve Properties of Alumina-spinel Low Cement Castables

A basic alumina -spinel low cement castables （ castables A） and another castables （ castables B） with 5% addition of sodium hexametaphosphate were prepared and heat treated at 110 ℃, 900℃ and 1 400 ℃. It is shown that after heat treating at 110 ℃ , cold crushing strength （CCS） of castables B is more than 3 times of castables A and apparent porosity （ AP ） is less than half of castables A. The presence of Mg2P207 and AIPO4 · 2H2O is the main difference. At 800- 1 000 ℃ that hydraulic bond reverses to dehydrate condition and castables A becomes weak with high porosity, castables B shows a CCS more than 4 times of castables A. Needles of magnesium phosphate are responsible for reinforcing microstructure of castables B at 900 ℃. After firing at 1 400 ℃, castables B shows extra ordinary CCS of more than 100 MPa. Reasons were discussed with X-ray diffraction and scanning electron microscopy.