Shock Raman spectra and structural transformation of powdered TKX-50 by the plate impact experiments combined with real-time Raman detection

As an energetic material of great interest,the work capacity of dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate(TKX-50)has been questioned recently.Although some research groups have explored the reasons for the low working ability of TKX-50,the plane impact experiment on powdered TKX-50 is obviously closer to the practical application,and the conclusions based on this are more guiding.Hence,we performed shock Hugoniot measurements of powdered TKX-50 between 5.65 and 16.29 GPa.The plane impact experiments of powdered TKX-50 were carried out and the shocked Raman spectra were collected.By Raman spectroscopy analysis,a new peak of powdered TKX-50 was found between19.47 GPa and 24.96 GPa,which may be caused by decomposition/phase transition and was related with the low work capacity.

Evolution of molecular structure of TATB under shock loading from transient Raman spectroscopic technique

By combination of the transient Raman spectroscopic measurement and the density functional theoretical calculations,the structural evolution and stability of TATB under shock compression was investigated.Due to the improvement in synchronization control between two-stage light gas gun and the transient Raman spectra acquisition,as well as the sample preparation,the Raman peak of the N-O mode of TATB was firstly observed under shock pressure up to 13.6 GPa,noticeably higher than the upper limit of 8.5 GPa reported in available literatures.By taking into account of the continuous shift of the main peak and other observed Raman peaks,we did not distinguish any structural transition or any new species.Moreover,both the present Raman spectra and the time-resolved radiation of TATB during shock loading showed that TATB exhibits higher chemical stability than previous declaration.To reveal the detailed structural response and evolution of TATB under compression,the density functional theoretical calculations were conducted,and it was found that the pressure make N-O bond lengths shorter,nitro bond angles larger,and intermolecular and intra-molecular hydrogen bond interactions enhanced.The observed red shift of Raman peak was ascribed to the abnormal enhancement of H-bound effect on the scissor vibration mode of the nitro group.

Co-Ru alloy nanoparticles decorated onto two-dimensional nitrogen doped carbon nanosheets towards hydrogen/oxygen evolution reaction and oxygen reduction reaction

Constructing highly-efficient electrocatalysts toward hydrogen evolution reaction(HER)/oxygen evolution reaction(OER)/oxygen reduction reaction(ORR)with excellent stability is quite important for the development of renewable energy-related applications.Herein,Co-Ru based compounds supported on nitrogen doped two-dimensional(2D)carbon nanosheets(NCN)are developed via one step pyrolysis procedure(Co-Ru/NCN)for HER/ORR and following low-temperature oxidation process(Co-Ru@RuO_(x)/NCN)for OER.The specific 2D morphology guarantees abundant active sites exposure.Furthermore,the synergistic effects arising from the interaction between Co and Ru are crucial in enhancing the catalytic performance.Thus,the resulting Co-Ru/NCN shows remarkable electrocatalytic performance for HER(70 mV at 10 mA cm^(-2))in 1 M KOH and ORR(half-wave potential E_(1/2)=0.81 V)in 0.1 M KOH.Especially,the Co-Ru@RuO_(x)/NCN obtained by oxidation exhibits splendid OER performance in both acid(230 mV at 10 mA cm^(-2))and alkaline media(270 mV at 10 mA cm^(-2))coupled with excellent stability.Consequently,the fabricated two-electrode water-splitting device exhibits excellent performance in both acidic and alkaline environments.This research provides a promising avenue for the advancement of multifunctional nanomaterials.

丁基橡胶的结构对硫化胶疲劳性能的影响

橡胶的机械疲劳过程复杂,影响因素众多。文中对不同微观结构的丁基橡胶进行室温屈挠龟裂实验,应用红外光谱仪和场发射扫描电子显微镜,分析了硫化胶屈挠疲劳前后分子链结构和微观形貌的变化。实验结果表明,不饱和度高的丁基橡胶硫化速度较快,屈挠过程中硫化胶表面热氧老化程度较高;相对分子质量相近的2种丁基橡胶不饱和度高的硫化胶的抗机械疲劳性能较好;屈挠龟裂过程中异相颗粒处的应力集中是导致形成龟裂裂纹的主要原因。

聚乳酸材料的化学解聚研究进展

聚乳酸(PLA)作为一种性能优良的生物降解材料,被用于工业、包装业及医药业等领域。随着PLA的广泛使用,其生产和消耗的数量急剧增加,最终导致废旧PLA的堆积日益严重。尽管PLA能在自然条件下降解,但降解周期过长,降解产物也无法直接进行循环再利用。通过化学回收法可将PLA材料进行解聚,生成相应的小分子产物,产物经分离、纯化后可重新作为生产PLA的单体或合成其它化工产品的原料,从而实现资源的循环利用。文中综述了近年来国内外聚乳酸(PLA)材料的化学降解回收产品的研究现状,介绍了几种主要的化学解聚方法,包括热裂解、水解、醇解、酶解及光解等,并对各方法的优缺点进行了分析与总结。最后,对PLA的化学降解进行了展望。

Risk assessment models of integrative medicine indicators for malignant transformation of chronic atrophic gastritis:A registry study protocol

Objective:Traditional Chinese medicine(TCM)and modern medicine have both been used in arresting malignant transformation of chronic atrophic gastritis(CAG)in China with good therapeutic effect.However,no studies have been undertaken to assess the risk of malignant transformation in CAG patients using both modern medicine and TCM features.Our study aimed to develop risk assessment models for malignant transformation of CAG combining indicators of both TCM and modern medicine.These models will facilitate early warning and control of malignant transformation of CAG from the perspective of evidence-based integrative medicine.Methods:In the proposed registry study,a total of 1000 eligible CAG patients will be recruited from four hospitals in China.A 10-year follow-up study will be conducted both on-site and off-site to track the events of malignant transformation.Frequency analysis and chi-squared tests will be used to perform the comparative analysis on the prevalence of malignant transformation events and indicators in TCM or modern medicine in different groups.A multivariate Cox proportional hazard model will be used to perform correlation analyses of malignant transformation events and factors of TCM or modern medicine.Conclusion:The proposed study has been designed with a large sample size and long follow-up period,in which wide-ranging modern medicine and TCM indicators can be gathered over the whole process of malignant transformation of CAG.Based on this study,risk assessment models for malignant transformation ofCAGmaybe constructed fromthe perspective of integrative medicine.This may provide clinicians and patients with an optimized early warning system as well as prevention strategies for malignant transformation of CAG.

Dahuang Fuzi decoction reduces inflammation levels and alleviates intestinal mucosal barrier damage in septic rats

Objective:To investigate the protective effect of Dahuang Fuzi Decoction(DHFZD),a traditional Chinese prescription,at alleviating sepsis-induced inflammation and gut barrier damage in rats.Methods:Forty clean-grade male Sprague-Dawley rats were divided randomly into three groups:normal control group(NCG,n?10),model control group(MCG,n?15)and DHFZD-treated group(DHFZDG,n?15).NCG rats were sham operated on and used as the controls,whereas MCG and DHFZDG rats were used to replicate the rat sepsis model using cecal ligation and puncture(CLP).The DHFZDG rats received DHFZD by gavage(4.5 mg/g of body weight)2 h prior to CLP and after its successful induction,while the NCG and MCG rats received equivalent amounts of sterilized water by gavage.All rat groups were starved and had free access to water.At 24 h post-experimental set up,the mortality of rats in each group was recorded,and peritoneal inflammation assessment and pathological changes related to the intestinal mucosal injury index(IMII)in the surviving rats were evaluated.D-lactic acid,tumor necrosis factor(TNF)-a,interleukin(IL)-6 and IL-10 peripheral blood concentrations,along with secretory immunoglobulin A(sIgA)in the intestinal mucosa were evaluated by enzyme-linked immunosorbent assays.Gut microbes were detected using 16S rRNA gene sequencing.Results:DHFZD reduced sepsis-related mortality in the rats.Moreover,it alleviated peritoneal inflammation and pathological changes according to the IMII.DHFZD reduced serum procalcitonin,TNF-a and IL-6 concentrations,but not the IL-10 concentration.It also reduced serum D-lactic acid and increased sIgA concentrations in intestinal mucosa.Notably,DHFZDG restored gut microbiota diversity and regulated the decrease in Bacteroidetes induced by sepsis,compared with the MCG rats.Conclusion:DHFZDG may play a protective role in sepsis by alleviating sepsis-induced inflammation and gut barrier damage in rats.

The race to the nociceptor: mechanical versus temperature effects in thermal pain of dental neurons

The sensing of hot and cold stimuli by dental neurons differs in several fundamental ways. These sensations have been characterized quantitatively through the measured time course of neural discharge signals that result from hot or cold stimuli applied to the teeth of animal models. Although various hypotheses have been proposed to explain the underlying mechanism, the ability to test competing hypotheses against experimental recorded data using biophysical models has been hindered by limitations in our understanding of the specific ion channels involved in nociception of dental neurons. Here we apply recent advances in established biophysical models to test the competing hypotheses. We show that a sharp shooting pain sensation experienced shortly following cold stimulation cannot be attributed to the activation of thermosensitive ion channels, thereby falsifying the so-called neuronal hypothesis, which states that rapidly transduced sensations of coldness are related to thermosensitive ion channels. Our results support a central role of mechanosensitive ion channels and the associated hydrodynamic hypothesis. In addition to the hydrodynamic hypothesis, we also demonstrate that the long time delay of dental neuron responses after hot stimulation could be attributed to the neuronal hypothesis-that a relatively long time is required for the temperature around nociceptors to reach some threshold. The results are useful as a model of how multiphysical phenomena can be combined to provide mechanistic insight into different mechanisms underlying pain sensations.

Implications of Israeli Agricultural Water Price Sharing System to China

This paper introduces Israeli agricultural water price sharing system. According to Israeli agricultural water cost composition,water price sharing by farmers as well as government subsidy and its forms,the financial subsidy-based agricultural water price system has been established on the basis of the farmers' income in our country and reasonable water price sharing,thus to promote the development of water-saving agriculture in China.

Symptom characteristics and prevalence of qi deficiency syndrome in people of varied health status and ages: A multicenter cross-sectional study

Objective:Aging caused by a deficiency syndrome can be found in ancient and modern traditional Chinese medicine literature.Qi deficiency syndrome(QDS)is a vital factor in the aging process.This study aimed to establish a full-scale trial to evaluate the prevalence,symptom severity,frequency,and distribution of QDS in different age groups and varying health status to elucidate the role of qi deficiency in the aging process and deterioration of health.Methods:This cross-sectional study was conducted in four hospitals in China,and data from 1220 participants were included.The participants,aged between 20 and 79 years,completed questionnaires that recorded prevalence of QDS and severity or frequency of relevant symptoms,then were interviewed by investigators.We used frequency analysis and chi-squared tests to perform comparative analysis of prevalence in different age and health groups;we used a ranksum tests for quantitative analysis of symptoms severity and frequency scores;we performed a regression analysis of correlation between syndrome occurrence and potential factors using nonconditional binary logistic stepwise regression of numerical variables.P<0.05 was considered statistically significant.Results:Prevalence,symptom severity and frequency scores of QDS showed a rising trend when physical condition worsened,rather than when age increased.Health status,fatigue,shortness of breath or no desire to talk,spontaneous sweating,swollen tongue with teeth marks on side,and deficient and weak pulse,rather than increasing age were contributing factors to this syndrome.Distribution of QDS in certain health and age stages showed remarkable irregularities.Conclusions:Qi deficiency may be a contributing factor for sub-health(sub-optimal health)and chronic diseases rather than aging.It may play a crucial role in chronic disease pathogenesis of young and middle-aged people,and in sub-health pathogenesis of older adults.Recognition of the warning signs and symptoms of QDS may lead to early intervention and prevention of subhealth,and chronic diseases.

Effect of viscoelasticity on skin pain sensation

Pain sensation may appear under long-lasting mechanical stimulation. Although people have the experience that pain sensation generally decreases with time while the stimulation remains, the underlying mechanism remains elusive. We experimentally studied the thermal and strain rate- dependent viscoelastic behavior of skin in uniaxial stretch and numerically investigated the effects of temperature and strain rate on pain sensation. The results indicate that the viscosity of skin tissue decreases with increasing temperature and reducing strain rate, which subsequently decreases the discharge frequency of skin nociceptor and thus relieves the pain sensation. The results would contribute to the understanding of pain relief mechanism and optimizing for mechanical treatment.

Research on Management Mode of Small-scale Irrigation Works for Farmland Based on Self-governance

The paper analyzes the practical use of management mode of small-scale farmland irrigation works in China,and studies various problems existing in the present management mode.It puts forward a mode named Water-consumer Association which is the most practical one at present.It points out some rules which must be mastered in solving problems appearing in using this mode.

堪为楷模的苏氏家风

眉山三苏以文学名世,带动了一方向学之风。苏氏家风倡导在家敦亲睦族,为官勤勉公正,善于因材施教,重视读史,推崇“华实相副”的学风。三苏家风传统,堪为世代楷模。

巧妙的稀掺杂策略实现高性能GeTe热电材料

In thermoelectrics,doping is essential to augment the figure of merit.Traditional strategy,predomina ntly heavy doping,aims to optimize carrier concentration and restrain lattice thermal conductivity.However,this tactic can severely hamper carrier transport due to pronounced point defect scattering,particularly in materials with inherently low carrier mean-free-path.Conversely,dilute doping,although minimally affecting carrier mobility,frequently fails to optimize other vital thermoelectric parameters.Herein,we present a more nuanced dilute doping strategy in GeTe,leveraging the multifaceted roles of small-size metal atoms.A mere 4%CuPbSbTe_(3)introduction into GeTe swiftly suppresses rhombohedral distortion and optimizes carrier concentration through the aid of Cu interstitials.Additionally,the formation of multiscale microstructures,including zero-dimensional Cu interstitials,one-dimensional dislocations,two-dimensional planar defects,and three-dimensional nanoscale amorphous GeO_(2)and Cu_(2)GeTe_(3)precipitates,along with the ensuing lattice softening,contributes to an ultralow lattice thermal conductivity.Intriguingly,dilute CuPbSbTe_(3)doping incurs only a marginal decrease in carrier mobility.Subsequent trace Cd doping,employed to alleviate the bipolar effect and align the valence bands,yields an impressive figure-of-merit of 2.03 at 623 K in(Ge_(0.97)Cd_(0.03)Te)_(0.96)(CuPbSbTe_(3))_(0.04).This leads to a high energyconversion efficiency of 7.9%and a significant power density of 3.44 W cm^(-2)at a temperature difference of 500 K.These results underscore the invaluable insights gained into the constructive role of nuanced dilute doping in the concurrent tuning of carrier and phonon transport in GeTe and other thermoelectric materials.

Manipulation of metavalent bonding to stabilize metastable phase:A strategy for enhancing zT in GeSe

Exploration of metastable phases holds profound implications for functional materials.Herein,we engineer the metastable phase to enhance the thermo-electric performance of germanium selenide(GeSe)through tailoring the chemical bonding mechanism.Initially,AgInTe2 alloying fosters a transition from stable orthorhombic to metastable rhombohedral phase in GeSe by substantially promoting p-state electron bonding to form metavalent bonding(MVB).Besides,extra Pb is employed to prevent a transition into a stable hexagonal phase at elevated temperatures by moderately enhancing the degree of MVB.The stabilization of the metastable rhombohedral phase generates an optimized bandgap,sharpened valence band edge,and stimulative band convergence compared to stable phases.This leads to decent carrier concentra-tion,improved carrier mobility,and enhanced density-of-state effective mass,culminating in a superior power factor.Moreover,lattice thermal conductivity is suppressed by pronounced lattice anharmonicity,low sound velocity,and strong phonon scattering induced by multiple defects.Consequently,a maximum zT of 1.0 at 773 K is achieved in(Ge_(0.98)Pb_(0.02)Se)_(0.875)(AgInTe_(2))_(0.125),resulting in a maximum energy conversion efficiency of 4.90%under the temperature difference of 500 K.This work underscores the significance of regulating MVB to stabilize metastable phases in chalcogenides.

熵工程提高(GeTe)_(x)(AgSb_(0.5)Bi_(0.5)Te_(2))_(1-x)的热电性能和显微硬度

作为一种材料基因特性的内禀属性,构型熵是材料基因组中一个新兴的指征因子.设计具有高构型熵的多组元热电材料,可以通过严重的晶格畸变显著降低晶格热导率,并通过提高晶体对称性改善塞贝克系数.然而,高构型熵也造成了载流子迁移率的恶化,从而限制了zT值的改善.本文通过在众所周知的(GeTe)_(1-x)(AgSbTe_(2))_(x),即TAGS合金中用Bi取代一半的Sb,设计了(GeTe)_(1-x)(AgSb_(0.5)Bi_(0.5)Te_(2))_(x),又称TABGS合金,以证明熵工程的有效性.鉴于TAGS合金的载流子平均自由程较低,已接近Mott-Ioffe-Regel极限,进一步的Bi置换和构型熵增加不会再损害载流子迁移率.此外,通过高构型熵抑制菱方-立方相变和降低的载流子浓度有助于大幅提高Seebeck系数.而且,AgSb_(0.5)Bi_(0.5)Te_(2)合金化诱导的多尺度微观结构和减小的声速有效地抑制了晶格热导率.因此,(GeTe)_(0.80)(AgSb_(0.5)Bi_(0.5)Te_(2))_(0.20)的最高zT值在723 K达到了1.60,300到773 K之间的平均zTave值达到了1.23.同时,由于固溶硬化其室温维氏硬度达到了2.21 GPa.这些结果强调了熵工程在提高热电性能方面的有效性,特别是对大量具有本征低载流子迁移率的材料而言.

Flexible nanocomposite electrodes with optimized hybrid structure for improved low-grade heat harvest via thermocells

Thermal energy is ubiquitous and constantly generated in nature and society.Thermocells(TECs)represent a promising energyconversion technology that can directly translate thermal energy into electricity with a large thermopower,thus having attracted considerable attention in recent years.Nevertheless,the use of noble platinum electrodes in TECs has substantially limited their widespread applications,as the scarcity of platinum element increases the cost of materials,and its intrinsic rigidity is not conducive to flexible and wearable applications under heat sources with complex surface geometry.Herein,we propose a facile hybridizing route to constructing flexible electrodes with optimized nanostructures.The flexible composite electrode is fabricated by decorating a single-walled carbon nanotube network with conducting polypyrrole nanospheres through controlled electrochemical deposition.With refined interfacial nanostructures,the resultant composite film can facilitate carrier transport/transfer at the electrolyte-electrode interface,and thereby shows superior overall thermoelectrochemical performance to noble platinum electrode.The TEC employing the flexible composite electrodes yields a maximum output power of 2.555μW under the temperature difference of 30 K,and a device comprising 6 TEC units is assembled to efficiently utilize waste heat and human body heat,revealing the high potential of low-grade heat harvesting.

Inhibiting the bipolar effect via band gap engineering to improve the thermoelectric performance in n-type Bi_(2-x)Sb_(x)Te_(3)for solid-state refrigeration

To date,the benchmark Bi_(2)Te_(3)-based alloys are still the only commercial material system used for ther-moelectric solid-state refrigeration.Nonetheless,the conspicuous performance imbalance between the p-type Bi_(2-x)Sb_(x)Te_(3)and n-type Bi_(2)Te_(3-x)Se_(x) legs has become a major obstacle for the improvement of cooling devices to achieve higher efficiency.In our previous study,novel n-type Bi_(2-x)Sb_(x)Te_(3)alloy has been pro-posed via manipulating donor-like effect as an alternative to mainstream n-type Bi_(2)Te_(3-x)Se_(x).However,the narrow bandgap of Bi_(2-x)Sb_(x)Te_(3)provoked severe bipolar effect that constrained the further improvement of zT near room temperature.Herein,we have implemented band gap engineering in n-type Bi_(1.5)Sb_(0.5)Te_(3)by employing isovalent Se substitution to inhibit the undesired intrinsic excitation and achieve the dis-tinguished room-temperature zT.First,the preferential occupancy of Se at Te^(2)site appropriately enlarges the band gap,thereby concurrently improving the Seebeck coefficient and depressing the bipolar thermal conductivity.In addition,the Se alloying mildly suppresses the compensation mechanism and essentially preserves the already optimized carrier concentration,which maintains the peak zT near room tempera-ture.Moreover,the large strain field and mass fluctuation generated by Se alloying leads to the remark-able reduction of lattice thermal conductivity.Accordingly,the zT value of Bi_(1.5)Sb_(0.5)Te_(2.8)Se_(0.2)reaches 1.0 at 300 K and peaks 1.1 at 360 K,which surpasses that of most well-known room-temperature n-type thermoelectric materials.These results pave the way for n-type Bi_(2-x)Sb_(x)Te_(3)alloys to become a new and promising top candidate for large-scale solid-state cooling applications.

Two-step phase manipulation by tailoring chemical bonds results in high-performance GeSe thermoelectrics

In thermoelectrics,phase engineering serves a crucial function in deter-mining the power factor by affecting the band degeneracy.However,for low-symmetry compounds,the mainstream one-step phase manipulation strategy,depending solely on the valley or orbital degeneracy,is inadequate to attain a high density-of-states effective mass and exceptional zT.Here,we employ a distinctive two-step phase manipulation strategy through stepwise tailoring chemical bonds in GeSe.Initially,we amplify the valley degeneracy via CdTe alloying,which elevates the crystal symmetry from a covalently bonded orthorhombic to a metavalently bonded rhombohedral phase by significantly suppressing the Peierls distortion.Subsequently,we incorporate Pb to trigger the convergence of multivalence bands and further enhance the density-of-states effective mass by moderately restraining the Peierls distortion.Additionally,the atypical metavalent bonding in rhombohedral GeSe enables a high Ge vacancy concentration and a small band effective mass,leading to increased carrier concentration and mobility.This weak chemical bond along with strong lattice anharmonicity also reduces lattice thermal conductivity.Consequently,this unique property ensemble contributes to an outstanding zT of 0.9 at 773 K for Geo.8oPbo.2oSe(CdTe)o.25.This work underscores the pivotal role of the two-step phase manipulation by stepwise tailoring of chemical bonds in improving the thermoelectric performance of p-bonded chalcogenides.

封装有Ni掺杂FeP纳米颗粒的氮掺杂碳纳米管作为双功能电催化剂

清洁能源支撑的电解海水技术是公认的最有前途的未来可持续绿色制氢途径.商用贵金属催化剂储量低、成本昂贵,且在复杂离子环境下容易快速失活的特性,严重阻碍了电解海水技术的工业化发展.本工作通过Ni掺杂Fe团簇催化碳纳米管生长,再气体磷化法,成功构建了一种含Ni掺杂FeP纳米颗粒封端的新型氮掺杂碳纳米管交织结构(NFP@NC).独特的N-CNTs交织网络,以及N-CNTs和Ni掺杂FeP的强相互作用提供了快速的传质途径,提高了气体逸出效率,并显著增强了催化剂稳定性.NFP@NC在10 mA cm^(−2)的电流密度下的析氧反应过电位为280 mV,析氢反应过电位为206 mV,低于大多数报道的铁基催化剂.本研究为构建交织的碳纳米管网络和制备高性能双功能海水电解催化剂提供了一种有效的途径.