Noether＇s theorem and one-step corrections method for holonomic system

In this paper, a new computational method for improving the accuracy of numerically computed solutions is introduced. The computational method is based on the one-step method and conserved quantities of holonomic systems are considered as kinematical constraints in this method.

One-step green method to prepare progressive burning gun propellant through gradient denitration strategy

Gradiently denitrated gun propellant(GDGP)prepared by a“gradient denitration”strategy is obviously superior in progressive burning performance to the traditional deterred gun propellant.Currently,the preparation of GDGP employed a tedious two-step method involving organic solvents,which hinders the large-scale preparation of GDGP.In this paper,GDGP was successfully prepared via a novelty and environmentally friendly one-step method.The obtained samples were characterized by FT-IR,Raman,SEM and XPS.The results showed that the content of nitrate groups gradiently increased from the surface to the core in the surface layer of GDGP and the surface layer of GDGP exhibited a higher compaction than that of raw gun propellant,with a well-preserved nitrocellulose structure.The denitration process enabled the propellant surface with regressive energy density and good progressive burning performance,as confirmed by oxygen bomb and closed bomb test.At the same time,the effects of different solvents on the component loss of propellant were compared.The result showed that water caused the least component loss.Finally,the stability of GDGP was confirmed by methyl-violet test.This work not only provided environmentally friendly,simple and economic preparation of GDGP,but also confirmed the stability of GDGP prepared by this method.

Remove of Phenolic Compounds in Water by Low-Temperature Plasma: A Review of Current Research

Phenolic compounds have very strong toxicity, so it has been paid sharply attention to find an effective way of controlling the wastewater containing phenolic compounds. The work on this subject done by domestic and overseas scholars is studied in this paper, and the progress of researches on low-temperature plasma treatment is summarized through the electrical discharge types, mechanism, kinetics of phenolic compounds decomposition and combination of several methods with low-temperature plasma treatment. In addition, the crucial problem and the developing tendency on low-temperature plasma treatment for phenol-bearing wastewater are briefly discussed.

Research progress and development direction of low-temperature drilling fluid for Antarctic region

By combing the characteristics of drilling in Antarctic region, performance requirements on drilling fluid for Antarctic low temperature conditions, and research progress of low temperature drilling fluid, current problems of the drilling fluid have been sorted out, and the development direction of the drilling fluid has been pointed out. Drilling in the Antarctic region mainly includes drilling in snow, ice and subglacial rock formations, and drilling in Antarctic low temperature conditions will face problems in four aspects:(1) low temperature and large temperature changes in the drilling area;(2) likely well leakage and drillstring-sticking in the snow layer, creep in the ice layer, ice chip gathering jamming in the warm ice layer, well wall collapse in the subglacial rock formations;(3) lack of infrastructure and difficulty in logistical support;(4) fragile environment and low carrying capacity. After years of development, progresses have been made on low-temperature drilling fluids for the Antarctic region. Low-temperature petroleum-based drilling fluid, ethanol/ethylene glycol-based drilling fluid, ester-based drilling fluid and silicone oil-based drilling fluid have been developed. However, these drilling fluids have problems such as insufficient low-temperature tolerance, low environmental performance and weak wellbore stability, etc. In order to meet the performance requirements of drilling fluid under low-temperature conditions in Antarctic region, the working mechanisms of low-temperature drilling fluid must be examined in depth;environment-friendly low-temperature base fluid of drilling fluid and related additives must be developed to prepare environmentally friendly low temperature drilling fluid systems;multi-functional integrated adjustment method for drilling fluid must be worked out to ensure well wall stability and improve cutting-carry capacity when drilling ice formations and ice-rock interlayers;and on-site support operation codes must be established to provide technical support for Antarctic drilling.

Constraint Stabilization and One-Step Correction Method for Dynamical Systems

A computational method of constraint stabilization and correction is introduced. The method is based on the Baumgart＇s one-step method. Constraint conditions are addressed to stabilize and correct the solution. Two examples are given to illustrate the results of the method.

A LOW-PRESSURE AND ONE-STEP METHOD FOR THE SYNTHESIS OF ALKYLIDYNETRICOBALT NONACARBONYL CLUSTERS:RCCo_8(CO)_9

Metal clusters RCCo_3(CO)_9(R-H,C1,Br,CH_3,Ph) were prepared in 18.8-57.3% yields from the reaction of cobalt(Ⅱ)salt and RCX_a under mild PTC conditions(latm CO,25℃).The cobalt salt was reduced to Co(CO)_4 in the presence of Na_3S_2O_4.

Low-temperature synthesis of ultrasmall spinel MnxCo3-xO4 nanoparticles for efficient oxygen reduction

Spinel-type manganese-cobalt oxides have been regarded as important class of electrocatalysts for oxygen reduction reaction(ORR).However,they are usually synthesized through oxidation-precipitation under aqueous ammonia and then crystallization at high temperature(150–180℃),which not only increases the energy consumption but also induces the growth of particles that is unfavorable for ORR.Herein,through a facile precipitation-dehydration method,ultrasmall spinel manganese-cobalt oxide nanoparticles(~5 nm)homogeneously dispersed on conductive carbon black(MnxCo3-xO4/C)were fabricated at low temperature(60℃).And the bimetallic composite oxide(Mn1.5Co1.5O4/C)with cubic spinel structure and high Mn content exhibits remarkable enhancement of ORR activity and stability compared with single metal oxide(both Mn3O4/C and Co3O4/C).The essential reason for the enhancement of activity can be attributed to the presence of the mixed Mn^3+ and Mn^4+ cations in Mn1.5Co1.5O4/C.Moreover,the ORR activity of Mn1.5Co1.5O4/C is comparable to that of commercial 20 wt% Pt/C,and the relative current density only decreases 1.4% after 12 h test,exceeding that of Pt/C and most reported manganese-cobalt oxide electrocatalysts.

Low-temperature Denitration Mechanism of NH_(3)-SCR over Fe/AC Catalyst

To study the modification mechanism of activated carbon(AC)by Fe and the low-temperature NH_(3)-selective catalytic reduction(SCR)denitration mechanism of Fe/AC catalysts,Fe/AC catalysts were prepared using coconut shell AC activated by nitric acid as the support and iron oxide as the active component.The crystal structure,surface morphology,pore structure,functional groups and valence states of the active components of Fe/AC catalysts were characterised by X-ray diffraction,scanning electron microscopy,nitrogen adsorption and desorption,Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy,respectively.The effect of Fe loading and calcination temperature on the low-temperature denitration of NH_(3)-SCR over Fe/AC catalysts was studied using NH_(3)as the reducing gas at low temperature(150℃).The results show that the iron oxide on the Fe/AC catalyst is spherical and uniformly dispersed on the surface of AC,thereby improving the crystallisation performance and increasing the number of active sites and specific surface area on AC in contact with the reaction gas.Hence,a rapid NH_(3)-SCR reaction was realised.When the roasting temperature remains constant,the iron oxide crystals formed by increasing the amount of loading can enter the AC pore structure and accumulate to form more micropores.When the roasting temperature is raised from 400 to 500℃,the iron oxide is mainly transformed fromα-Fe_(2)O_(3)toγ-Fe_(2)O_(3),which improves the iron oxide dispersion and increases its denitration active site,allowing gas adsorption.When the Fe loading amount is 10%,and the roasting temperature is 500℃,the NO removal rate of the Fe/AC catalyst can reach 95%.According to the study,the low-temperature NH_(3)-SCR mechanism of Fe/AC catalyst is proposed,in which the redox reaction between Fe~(2+)and Fe~(3+)will facilitate the formation of reactive oxygen vacancies,which increases the amount of oxygen adsorption on the surface,especially the increase in surface acid sites,and promotes and adsorbs more reaction gases(NH_(3),O_(2),NO).The transformation from the standard SCR reaction to the fast SCR reaction is accelerated.

Synthesis of Codon-optimized Human Interleukin-18 Gene by Combination of Chemical and Enzymatic Method

According to the amino acid sequence and codon preference of E. coli, the human interleukin-18（IL-18） gene was optimized to avoid the rare codons. The total length of the synthesized gene is 571 bp; 18 oligonucleotides, DNA fragments were designed and synthesized by the phosphoramidite four-step chemical method. The whole DNA sequence was synthesized by a one-step total gene synthesis method, and then inserted in pUC18 vector. Five positive clones identified by blue-white colony screening were sent to Shanghai Sangon Biological Engineering Technology and Service Co., Ltd. for sequencing. The sequencing result shows that one clone contained the complete correct gene in all the five positive clones.

Study on Free Surface and Channel Flow Induced by Low Temperature Plasma via Lattice Boltzmann Method

Active boundary layer flow control and boundary layer manipulation in the channel flow that was based on low temperature plasma were studied by means of a lattice Boltzmann method. Two plasma actuators were placed in a row to obtain the influence rule of their separation distance on the velocity profile at three locations and maximum velocity in the flow field. Two plasma actuators were placed symmetrically inside a channel to examine the effect of channel height and voltage on the velocity profile and flow rate. It was found that the channel height controls the distribution of flow velocity, which affected the flow rate and its direction. Increasing plasma voltage had a negative effect on the flow rate due to the generation of a larger and stronger flow vortex.

One-Step Multiplex PCR for Simultaneous Detection and Identification of Eight Medically Important <i>Candida</i>Species

Recently, the incidence of Candida infections has substantially increased. Conventional identification methods for Candida species are technically difficult to conduct and cannot accurately distinguish each species. The purpose of the present study was to design primers to identify and detect simultaneously eight medically important Candida species using one-step multiplex PCR. PCR primers were designed based on partial sequences of intergenic spacer (IGS) and internal transcribed spacer (ITS) genes of eight medically important Candida species. These primers were able to distinguish each Candida species and did not display cross-reactivity with representative Candida species other than the eight Candida species. Moreover, our developed one-step multiplex PCR method is accurate, specific, cost-effective, time-saving, and worked without requiring DNA extraction.

Simulation of bulk metal forming processes using one-step finite element approach based on deformation theory of plasticity

The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.

One-step Eco-friendly Fabrication of Antibacterial Polyester Via On-line Amination Reaction by Melt Coextrusion

The work is dedicated to develop a one-step eco-friendly method to prepare antibacterial polyethylene terephthalate(PET).We report a one-step eco-friendly method to manufacture antibacterial PET via on-line amination reaction by melt coextrusion.Beside evenly mixing of poly(hexamethylene guanidine)(PHMG)and PET in the melt coextrusion procedure,the amination reaction also occurred between PHMG and PET under high temperature(230-270℃).The antibacterial ability of composite PET showed obvious PHMG concentration dependence,and antibacterial activity reached more than 99%when PHMG content was 2.5 wt%.Moreover,LIVE/DEAD fluorescence test further confirmed that the composite PET could kill bacteria quickly and efiectively(within 30 min);while negligible cytotoxicity was observed to HSF and HUVEC cells.Onestep eco-friendly fabrication of composite antibacterial PET was accomplished by on-line melt coextrusion.The composite antibacterial PET has potential use in multiple fields to combat with pathogenic including textiles,packaging materials,decoration materials and biomedical devices,etc.

Methods for enhancing the capacity of electrode materials in low-temperature lithium-ion batteries

Lithium-ion batteries(LIBs)have evolved into the mainstream power source of ene rgy sto rage equipment by reason of their advantages such as high energy density,high power,long cycle life and less pollution.With the expansion of their applications in deep-sea exploration,aerospace and military equipment,special working conditions have placed higher demands on the low-temperature performance of LIBs.However,at low temperatures,the severe polarization and inferior electrochemical activity of electrode materials cause the acute capacity fading upon cycling,which greatly hindered the further development of LIBs.In this review,we summarize the recent important progress of LIBs in low-temperature operations and introduce the key methods and the related action mechanisms for enhancing the capacity of the various cathode and anode materials.It aims to promote the development of high-performance electrode materials and broaden the application range of LIBs.

In-situ-selective-UV crosslinking fabrication of solid liquid host guest electrolyte: A facile one-step method realizing highly flexible electrochromic device

Flexible electrochromic devices (FECDs) are promising candidates for the next generation of wearable electronics due to their low operating voltage and energy consumption. For the flexible electrochromic devices, the electrolyte is an important component. Typically, the electrolyte needs to be formulated according to the device structure and usage scenario. A high-performance electrolyte involves consideration of many factors, including choosing the right polymer, solvent, curing agent, and ion type to satisfy particular device specifications. In this work, a ultraviolet-curable solid–liquid host–guest (UV-SLHG) electrolyte is developed. Several aspects of performance are improved by introducing the solid–liquid coexisting microstructure without changing the electrolyte formulation, including excellent adhesion, a 30% increase in tensile characteristics, and a seven-fold increase in ionic conductivity when compared to a fully cured solid-state electrolyte. More importantly, the unique advantage of SLHG electrolytes lies that the thickness will not change significantly during bending. The FECD made by using the UV-SLHG-based electrolyte sustained 10,000 bending cycles at the bending radius of 2.5 mm while maintaining outstanding optical modulation. A wearable ring-type ECD and a battery-free FECD wine label were made as demonstrators. The UV-SLHG strategy is not only suitable for the FECDs but also universally applicable to other electrolyte-based of flexible electronics such as flexible capacitors and batteries.

Effect of Magnetic Field on Synthesis of Nano-FeOOH by Low-Temperature Neutralization Method

Using XRD,TEM and VSM methods,the phase,morphology and magnetic property of iron hydroxide oxide(FeOOH) which has been prepared by low-temperature neutralization reaction under different magnetic fields were analyzed.It can be found that the magnetic field had a great influence on the product.Acicular goethite(α-FeOOH) was synthetized without magnetic field.When the magnetic flux density was increased to 0.1T,γ-FeOOH was obtained.If the magnetic field intensity was raised to 0.5T,the product was all composed of δ-FeOOH.Moreover,the crystallization of FeOOH was greatly influenced by magnetic field as well.Thermodynamic calculation results show that the magnetic free energy of chemical reaction reached to more than hundreds KJ/mol when the magnetic field is applied.It meaned that the application of magnetic field was conducived to producing the products with higher susceptibility.Even under the low magnetic field,due to the stability of the reaction products was broken by the magnetic field,the magnetic free energy was also effective.

Physiochemical and Biological Properties of Modified Collagen Sponge from Porcine Skin

The aim of the present study was to compare one-step method to EDC/NHS crosslinking （EDC/NHS group） and one-step simultaneous method to EDC/NHS crosslinking and heparin immobilization （EDC/NHS- Heparin group） in improving physiochemical and biological properties of native collagen sponge （Control group）. Modified collagen sponge overcome the disadvantages of native collagen sponge. IR spectra suggest the change of the functional groups. DSC data indicate that the stability of caloric transformation in EDC/NHS group is slightly higher than that of EDC/NHS-Heparin group. The crosslinking degree, stability against enzymes, stability in morphologically and biomechanical properties of EDC/NHS-Heparin group are higher than those of EDC/NHS group, whereas, the water-binding capacity in EDC/NHS-Heparin group is lower than that of EDC/NHS group. HUVECs in EDC/NHS-Heparin group scaffold proliferate fast, migrate well and distribute uniformly. One-step simultaneous method gains the better effects in above aspects, heparinized collagen matrices increase in angiogenic potential and suit for defect repairing and tissue engineering.

High CO methanation activity on zirconia-supported molybdenum sulfide catalyst

In this study, different methods were used to prepare MoO3/ZrO2 catalysts for sulfur resistant methanation reaction. It was found that MoO3/ZrO2 catalyst prepared by one-step co-precipitation method achieved high methanation performance. CO conversion could reach up to 90% on 25 wt% MoO3/ZrO2 catalyst, much higher than that on the conventional 25 wt% MoO3/Al2O3 catalyst. The Mo-based catalysts were characterized by XRF, XRD, Raman, BET, TEM and H2-TPR etc. It was found that MoO3 particles were highly dispersed on ZrO2 support for 25 wt% MoO3/ZrO2 catalyst prepared at 65-85℃ because of its relatively larger pore size, which contributed to a high CO conversion. Meanwhile, when MoO3 loading exceeded the monolayer coverage, the formed crystalline MoO3 and ZrM020g might block the micropores of the catalyst and make the methanation activity declined. These results are useful for preparing highly efficient catalyst for CO methanation process.

Preparation of Nano-MnFe2O4 and Its Catalytic Performance of Thermal Decomposition of Ammonium Perchlorate

Nano-MnFe2O4 particles were synthesized by co-precipitation phase inversion method and low-temperature combustion method respectively, using MnCl2, FeCl3, Mn（NO3）2, Fe（NO3）3, NaOH and C6H8O7. X-ray diffraction （XRD）, transmission electron microscope （TEM）, Fourier transform infrared spectroscopy （FT-IR）, thermogravim-etry-differential thermal analysis （TG-DTA） and differential scanning calorimetry （DSC） were used to characterize the structure, morphology, thermal stability of MnFe2O4 and its catalytic performance to ammonium perchlorate. Results showed that single-phased and uniform spinel MnFe2O4 was obtained. The average particle size was about 30 and 20 nm. The infrared absorption peaks appeared at about 420 and 574 cm-1, and the particles were stable below 524 ℃. Using the two prepared catalysts, the higher thermal decomposition temperature of ammonium perchlorate was decreased by 77.3 and 84.9 ℃ respectively, while the apparent decomposition heat was increased by 482.5 and 574.3 J？g？1. The catalytic mechanism could be explained by the favorable electron transfer space provided by outer d orbit of transition metal ions and the high specific surface absorption effect of MnFe2O4 particles.

EFFICIENT ESTIMATION OF FUNCTIONAL-COEFFICIENT REGRESSION MODELS WITH DIFFERENT SMOOTHING VARIABLES

In this article,a procedure for estimating the coefficient functions on the functional-coefficient regression models with different smoothing variables in different coefficient functions is defined.First step,by the local linear technique and the averaged method,the initial estimates of the coefficient functions are given.Second step,based on the initial estimates,the efficient estimates of the coefficient functions are proposed by a one-step back-fitting procedure.The efficient estimators share the same asymptotic normalities as the local linear estimators for the functional-coefficient models with a single smoothing variable in different functions.Two simulated examples show that the procedure is effective.