Hybrid Multi-Infeed Interaction Factor Calculation Method Considering Voltage Regulation Control Characteristics of Voltage Source Converter

Voltage source converter based high voltage direct current(VSC-HVDC)can participate in voltage regulation by flexible control to help maintain the voltage stability of the power grid.In order to quantitatively evaluate its influence on the voltage interaction between VSC-HVDC and line commutated converter based high voltage direct current(LCC-HVDC),this paper proposes a hybrid multi-infeed interaction factor(HMIIF)calculation method considering the voltage regulation control characteristics of VSC-HVDC.Firstly,for a hybrid multi-infeed high voltage direct current system,an additional equivalent operating admittance matrix is constructed to characterize HVDC equipment characteristics under small disturbance.Secondly,based on the characteristic curve between the reactive power and the voltage of a certain VSC-HVDC project,the additional equivalent operating admittance of VSC-HVDC is derived.The additional equivalent operating admittance matrix calculation method is proposed.Thirdly,the equivalent bus impedance matrix is obtained by modifying the alternating current(AC)system admittance matrix with the additional equivalent operating admittance matrix.On this basis,the HMIIF calculation method based on the equivalent bus impedance ratio is proposed.Finally,the effectiveness of the proposed method is verified in a hybrid dual-infeed high voltage direct current system constructed in Power Systems Computer Aided Design(PSCAD),and the influence of voltage regulation control on HMIIF is analyzed.

构建Cu台阶位促进电催化CO_(2)还原制醇类化学品的研究

电催化CO_(2)制备高附加值的化学品是解决当前碳排放问题的可行技术路线之一.其中,合成醇类化合物因具有广泛用途和高价值而备受关注.在电催化CO_(2)还原合成多碳醇反应中,关键中间体*CH_(2)CHO容易发生热力学有利的脱氧反应而生成C2H4,降低了醇类产物的选择性.由于电催化CO_(2)还原是一个表面结构敏感的反应,因此可以通过设计Cu基催化剂的特定表面结构,实现对反应路径的有效调节,从而提升醇类产物的选择性.本课题组前期通过密度泛函理论(DFT)计算和主成分分析法等对Cu基催化剂的构效关系进行解析,说明配位不饱和的台阶位点有望高效地促进醇类产物的生成.本文进一步从实验角度,证明了配位不饱和的台阶位点是生成醇类产物的活性位点.本文采用CO分子作为还原剂制备了CuO衍生的金属Cu催化剂(COD-Cu),利用CO分子对Cu表面的重构作用,获得了具有丰富台阶位点的Cu催化剂.而通过H_(2)还原制备的金属Cu催化剂(HOD-Cu)对照样表面则多为平面位点.X射线衍射和原位拉曼光谱结果表明,CuO前驱体经过CO或H_(2)还原后被完全还原为金属态,并且在电化学还原条件下依旧呈现金属态,排除了催化剂价态对反应的影响.扫描电镜结果表明,两种催化剂的形貌没有明显区别,排除了催化剂形貌对反应的影响.高分辨透射电镜结果表明,COD-Cu表面因为CO的重构作用,产生相较于HOD-Cu更多的台阶位点,这与CO原位红外光谱结果一致(COD-Cu催化剂在2080 cm~(–1)波数处具有明显的台阶位点CO吸附峰).电化学CO_(2)还原活性测试结果表明,COD-Cu表现出更高的醇类产物选择性,相较于HOD-Cu,法拉第效率与部分电流密度均提升了5倍以上,醇类产物的法拉第效率达到40.5%,部分电流密度达到56.3 mAcm~(-2),产物中醇/烯烃比值为2.2.这表明台阶位点对调控反应路径促进醇类生成具有重要作用.结合原位衰减全反射表面增强傅里叶变换红外吸收光谱的阶跃电位和Ar气吹扫实验结果表明,COD-Cu因具有更多的台阶位点而表现出更高的催化CO_(2)到*CO反应活性,并有效促进后续的C–C偶联反应.通过热退火实验制备了具有不同台阶位点含量的COD-Cu催化剂,其台阶位点的含量与醇类产物的选择性保持良好的线性关系,进一步验证了台阶位点是促进醇类产物生成活性位点的结论.DFT结果也表明,台阶位点可以有效的提升关键中间体*CH_(2)CHO中C–O键强度,从而抑制C–O键断裂,促进醇类产物的生成.综上,本文提出了一种通过催化剂活性位点设计调控电催化CO_(2)还原反应路径的有效策略,为解析催化剂构效关系、明确活性位点提供参考.得益于催化科学的快速发展,具有高活性的CO_(2)还原电催化剂不断涌现,未来可在发展活性位点精细化调控方法、开发新型原位瞬态表征技术、创新催化剂失活机制原位研究方法等方面做出更多的努力.

A review of methods,applications and limitations for incorporating fluid flow in the discrete element method

The past decade has witnessed the substantial growth in research interests and progress on the subject of coupled hydro-mechanical processes in rocks and soils,driven mainly by the surge of research in unconventional hydrocarbon reservoirs and associated hazards.Many coupling techniques have been developed to include the effects of fluid flow in the discrete element method(DEM),and the techniques have been applied to a variety of geomechanical problems.Although these coupling methods have been successfully applied in various engineering fields,no single fluid/DEM coupling method is universal due to the complexity of engineering problems and the limitations of the numerical methods.For researchers and engineers,the key to solve a specific problem is to select the most appropriate fluid/DEM coupling method among these modeling technologies.The purpose of this paper is to give a comprehensive review of fluid flow/DEM coupling methods and relevant research.Given their importance,the availability or unavailability of best practice guidelines is outlined.The theoretical background and current status of DEM are introduced first,and the principles,applications,and advantages and disadvantages of different fluid flow/DEM coupling methods are discussed.Finally,a summary with speculation on future development trends is given.

Effect of Nd content on microstructure and mechanical properties of as-cast Mg-12Li-3Al alloy

In order to improve the mechanical properties of Mg-Li alloy with single β phase structure, Mg-12Li-3Al-xNd(x=0.3, 0.7, 1.1, 2.0wt.%) alloy was prepared. Subsequently, the as-cast microstructure and mechanical properties were observed and tested. The results showed that the structure of Mg-12Li-3Al-xNd(x=0.3, 0.7, 1.1, 2.0wt.%) as-cast alloy was composed of β phase matrix and Al_2Nd, Al_(11)Nd_3, MgLiAl_2, Al_4Li_9 and AlLi phases. With the increase of Nd content in the alloy, the Al-Nd intermetallic compounds have a trend to change from needle-like Al_(11)Nd_3 to granular Al_2Nd. The hardness of as-cast Mg-12Li-3Al-xNd(x=0.3, 0.7, 1.1, 2.0wt.%) alloy was stable at room temperature. The tensile strength of Mg-12Li-3Al-1.1Nd was as high as 180 MPa, the elongation rate of Mg-12Li-3Al-0.7Nd reached 53.7%, and the comprehensive mechanical properties of Mg-12Li-3Al-2.0Nd was the best. PLC phenomenon occurred during the tensile process of the alloys at room temperature. Therefore, the β-based Mg-Li alloy with good plasticity as well as enhanced strength can be obtained by a moderate addition of Nd and Al.

Improved Oxygen Evolution Kinetics and Surface States Passivation of Ni-Bi Co-Catalyst for a Hematite Photoanode

This paper describes the combinational surface kinetics enhancement and surface states passivation of nickel-borate （Ni-Bi） co-catalyst for a hematite （Fe_2O_3） photoanode. The Ni-Brmodified Fe_2O_3 photoanode exhibits a cathodic onset potential shift of 230 mV and a 2.3-fold enhancement of the photocurrent at 1.23 V, versus the reversible hydrogen electrode （RHE）. The borate （Bi） in the Ni-Bi film promotes the release of pro- tons for the oxygen evolution reaction （OER）.

Alternative Strategies Toward Sustainable Ammonia Synthesis

As one of the world’s most produced chemicals, ammonia(NH3) is synthesized by Haber-Bosch process. This century-old industry nourishes billions of people and promotes social and economic development. In the meantime, 3%-5% of the world’s natural gas and 1%-2% of the world’s energy reserves are consumed, releasing millions of tons of carbon dioxide annually to the atmosphere. The urgency of replacing fossil fuels and mitigating climate change motivates us to progress toward more sustainable methods for N2 reduction reaction based on clean energy. Herein, we overview the emerging advancement for sustainable N2 fixation under mild conditions, which include electrochemical, photo-, plasma-enabled and homogeneous molecular NH3 productions. We focus on NH3 generation by electrocatalysts and photocatalysts. We clarify the features and progress of each kind of NH3 synthesis process and provide promising strategies to further promote sustainable ammonia production and construct state-of-the-art catalytic systems.

Comparison of dental pulp periodontal therapy and conventional simple periodontal therapy as treatment modalities for severe periodontitis

BACKGROUND Severe periodontitis is a major oral health concern today as it can lead to loss of teeth.Conventional periodontal therapy has numerous pitfalls as it does not address the pulp-periodontal complex in its entirety.AIM To investigate the effect of dental pulp periodontal therapy on the levels of interleukin-1β(IL-1β)and IL-10 in gingival crevicular fluid(GCF)in patients with severe periodontitis.METHODS Eighty-six patients with severe periodontitis were randomly divided into a research group(n=43)and a control group(n=43).The control group was treated with simple periodontal therapy,and the research group was treated with dental pulp periodontal therapy.The total effective rates of the treatments;periodontal status before and after treatment through the measurement of the periodontal pocket probing depth(PPD),gingival sulcus bleeding index(SBI),mobility(MD),and plaque index(PLI);the levels of inflammatory factors IL-1βand IL-10 in the GCF;and the incidence of complications were calculated for both groups and compared using the Student’s t test and theχ^(2) test.RESULTS The total effective rate of treatment in the study group(93.02%)was higher than that in the control group(76.74%;P<0.05).While before treatment,there was no significant difference in the PLI,MD,SBI,or PPD between the two groups,the post-treatment values of PLI,MD,SBI,and PPD(4.71±0.16 mm,0.61±0.09 mm,0.96±0.17 mm,and 0.76±0.26 mm,respectively)were significantly lower(P<0.05)in the research group than in the control group(5.35±0.24 mm,0.93±0.15 mm,1.35±0.30 mm,and 1.04±0.41 mm,respectively).There was no significant difference in the level of IL-1βor IL-10 in the GCF before treatment between the two groups;after treatment,the IL-1βlevel in the research group(139.04±15.54 pg/mL)was significantly lower than that in the control group(156.35±18.10 pg/mL),and the level of IL-10 in the research group(7.98±1.01 ug/L)was higher than that in the control group(5.56±0.96 ug/L)(P<0.05).The incidence of complications in the study group(4.65%)was significantly lower than that of the control group(18.60%;P<0.05).CONCLUSION Endodontic therapy and periodontal treatment for patients with severe periodontitis can effectively reduce the levels of inflammatory factors in the GCF and the inflammatory reaction.In addition,it can improve the periodontal condition and the overall treatment effect,reduce the risk of complications,and ensure the safety of treatment.

Preparation of submicrocrystal Al-Ti-B master alloy and its influence on microstructure and properties of AZ91D

To improve the mechanical properties of AZ91D magnesium alloy,the submicrocrystal Al-Ti-B master alloy was prepared with copper mold inject casting method,and the influence of submicrocrystal Al-Ti-B master alloy on the microstructure and mechanical properties of AZ91D was investigated.Results show that,the distribution of Ti B_2 phase in submicrocrystal Al-Ti-B alloy is even and disperse,and the average size of Ti Al_3 phase is reduced from 10-30μm to～1μm.The properties of AZ91D refined with submicrocrystal Al-Ti-B master alloy are better than that with coarse-grained Al-Ti-B master alloy without copper mold inject casting.The tensile strength,elongation and Brinell hardness of AZ91D are increased by 10.6%,25%and 18.1%,respectively.Therefore,refinement of AZ91D with submicrocrystal Al-Ti-B that is obtained by copper mold inject casting is an effective method to improve its mechanical properties.

Old nest material functions as an informative cue in making nest-site selection decisions in the European Kestrel(Falco tinnunculus)

Background:For secondary cavity-nesting bird species that do not add lining materials to nests,the presence of old nest material or organic remains that have accumulated within nest cavities from previous breeding events may be a cue of nest-site quality.These materials potentially contain information about past breeding success in con-and heterospecifics and may improve the thermal insulation of eggs during incubation.However,few studies have addressed whether the presence of old nest materials serves as a cue for cavity-nesting raptors when choosing specific nest sites.Methods:We conducted a 9-year nest box experiment to test whether old nest materials from con-and heterospecifics serve as informative cues to the European Kestrel(Falco tinnunculus)when making nest selection decisions,as this species uses nest boxes without adding nesting material.Results:The presence of old nest materials and entrance size best discriminated nest boxes occupied by European Kestrels from unoccupied boxes.Nest boxes containing conspecific organic remains,artificial dry leaf and branch material,and material left behind by Great Tits(Parus major)were reused at higher rates,especially those containing conspecific nest material,than nest boxes containing true or simulated nest materials from predators.In 2010,no single nest box was occupied by the same banded individual that occupied the box in the previous year(10 females and 2 males were banded in 2009).Conclusions:European Kestrels preferred nest boxes containing old nest material over empty boxes,which is consistent with previous findings that they exploit con-and heterospecific cues when deciding where to settle and breed,as old nest or organic material provides substrate for incubating females.Kestrels may be able to assess the predation risks associated with a specific nest site based on experience or the presence of prey remains.The repeated use of nest boxes across breeding seasons by kestrels cannot be entirely ascribed to philopatry.This study provides evidence that old nest materials are potentially used as informative cues when making nest-site selection decisions in European Kestrels.

Design and Implementation of Open Source Online Evaluation System Based on Cloud Platform

In order to provide a good practice platform for the program design contestants and algorithm enthusiasts,this paper designs and implements a programming online evaluation system based on cloud platform,which is a web system that can return the test results of the program source codes submitted by users in real time.It realizes the automatic evaluation of the program design training questions.The system is implemented by the way of front-end and back-end separation and modular programming.The front-end of the web is implemented by Vue framework,the back-end is implemented by Django framework.The judgment core is written in C language for the sake of improving the efficiency of the system.Sandbox technology is used to ensure the security of the judgment system.Experimental results show that the system can meet the need of daily teaching and competition.

Sputtered Stainless Steel on Silicon Photoanode for Stable Seawater Splitting in Photoelectrochemical Flow Cell

Photoelectrochemical(PEC)seawater splitting is a promising method for the direct utilization of solar energy and abundant seawater resources for hydrogen production.Photoelectrodes are susceptible to various ions in seawater and complicated competitive reactions,resulting in the failure of photoelectrodes.This paper proposes the design and fabrication of diff erent sputtered stainless steel(SS)fi lms deposited on silicon photoanodes,completely isolating the electrolytes and semiconductor substrate.Upon coupling with the PEC flow cell,the back-illuminated photoanode coated with 316 SS cocatalyst achieves stable operation for 70 h in natural seawater with a highly alkaline KOH(30 wt.%,7.64 mol/L)electrolyte due to the remarkable protection eff ect of the substrate from stainless steel,while the PEC seawater splitting system achieves a record hydrogen production rate of 600μmol/(h·cm^(2)).An appropriate Ni/Fe ratio in the SS ensures remarkable oxygen evolution activity,while chromic oxide ensures the effective anticorrosion effect by adjusting the microenvironment of the photoanodes.Moreover,fabricating PEC flow cells with photoanodes coated with SS cocatalysts are a viable strategy for PEC seawater splitting.

Geographic range size patterns across plants and animals of Xinjiang,China

Patterns in species geographic range size are relatively well-known for vertebrates,but still poorly known for plants.Contrasts of these patterns between groups have rarely been investigated.With a detailed flora and fauna distribution database of Xinjiang,China,we used regression methods,redundancy analysis and random forests to explore the relationship of environment and body size with the geographic range size of plants,mammals and birds in Xinjiang and contrast these patterns between plants and animals.We found positive correlations between species range size and body size.The range size of plants was more influenced by water variables,while that of mammals and birds was largely influenced by temperature variables.The productivity variable,i.e.,Enhanced Vegetation Index(EVI)was far more correlated with range size than climatic variables for both plants and animals,suggesting that vegetation productivity inferred from remote sensing data may be a good predictor of species range size for both plants and animals.

Disease and Economic Burden of Kashin-Beck Disease—China,2021

What is already known about this topic?Kashin-Beck disease(KBD)is a chronic and degenerative osteoarthropathy characterized by cartilage degeneration.It is an endemic disease that is highly prevalent among the Chinese population and poses a significant health risk.What is added by this report?This is the first national report on the economic burden of KBD in China.According to the data from 2021,KBD has caused significant disease and economic burdens.The most substantial reduction in healthy life expectancy was observed among patients with degree II severity and those aged 60 years and older,resulting in a total indirect economic burden of 112.74 million Chinese Yuan(CNY).What are the implications for public health practice?The results of this study will contribute to informing the development of tailored prevention and control strategies by the government.These strategies will include targeted policies and recommendations for appropriate healthcare and financial subsidies,which will be based on the demographic characteristics of the endemic areas.

KHK-A promotes fructose-dependent colorectal cancer liver metastasis by facilitating the phosphorylation and translocation of PKM2

Excessive fructose diet is closely associated with colorectal cancer(CRC)progression.Nevertheless,fructose’s specific function and precise mechanism in colorectal cancer liver metastasis(CRLM)is rarely known.Here,this study reported that the fructose absorbed by primary colorectal cancer could accelerate CRLM,and the expression of KHK-A,not KHK-C,in liver metastasis was higher than in paired primary tumors.Furthermore,KHK-A facilitated fructose-dependent CRLM in vitro and in vivo by phosphorylating PKM2 at Ser37.PKM2 phosphorylated by KHK-A inhibited its tetramer formation and pyruvic acid kinase activity but promoted the nuclear accumulation of PKM2.EMT and aerobic glycolysis activated by nuclear PKM2 enhance CRC cells’migration ability and anoikis resistance during CRLM progression.TEPP-46 treatment,targeting the phosphorylation of PKM2,inhibited the pro-metastatic effect of KHK-A.Besides,c-myc activated by nuclear PKM2 promotes alternative splicing of KHK-A,forming a positive feedback loop.

Frameworked electrolytes:Ionic transport behavior and high mobility for solid state batteries

All solid-state batteries(ASSBs)are the holy grails of rechargeable batteries,where extensive searches are ongoing in the pursuit of ideal solid-state electrolytes.Nevertheless,there is still a long way off to the satisfactorily high(enough)ionic conductivity,long-term stability and especially being able to form compatible interfaces with the solid electrodes.Herein,we have explored ionic transport behavior and high mobility in the sub-nano pore networks in the framework structures.Macroscopically,the frameworked electrolyte behaves as a solid,and however in the(sub)-nano scales,the very limited number of solvent molecules in confinement makes them completely different from that in liquid electrolyte.Differentiated from a liquid-electrolyte counterpart,the interactions between the mobile ions and surrounding molecules are subject to dramatic changes,leading to a high ionic conductivity at room temperature with a low activation energy.Li+ions in the sub-nano cages of the network structure are highly mobile and diffuse rather independently,where the rate-limiting step of ions crossing cages is driven by the local concentration gradient and the electrostatic interactions between Li^(+)ions.This new class of frameworked electrolytes(FEs)with both high ionic conductivity and desirable interface with solid electrodes are demonstrated to work with Li-ion batteries,where the ASSB with LiFePO_(4)shows a highly stable electrochemical performance of over 450 cycles at 2℃ at room temperature,with an almost negligible capacity fade of 0.03‰ each cycle.In addition,the FE shows outstanding flexibility and anti-flammability,which are among the key requirements of large-scale applications.

基于Geohash与行政区划双层嵌套格网的生态环境监测数据组织管理与软件实现

生态环境监测为生态环境保护和监管提供了可靠、有效的数据,生态环境监测数据一体化组织管理是挖掘生态环境监测数据潜在价值的基础。现有的生态环境监测数据组织与管理方式因标准不统一、参考体系各异,难以集成管理、快速检索与统计分析。针对上述问题,提出了一种基于Geohash与行政区划双层嵌套格网混合索引机制,实现各类生态环境监测数据的一体化组织管理,满足海量多源异构生态环境监测数据的存储和快速检索。基于构建的Geohash与行政区划双层嵌套格网混合索引机制,研发了网格自动划分软件,实现生态环境监测数据的一体化组织、多维度检索、统计分析及实时展示,并以2021年全国秸秆火点矢量数据、2023年8月姜堰区扬尘源矢量数据及江苏省水库矢量数据为例验证了此软件的各项功能及其运行情况。结果表明:构建的双层嵌套混合索引机制能快速完成海量生态环境监测数据的格网建构与编码,结合业务需求完成最优格网选择,快速检索并统计不同空间尺度数据情况。

ASL-OOD:Hierarchical Contextual Feature Fusion with Angle-Sensitive Loss for Oriented Object Detection

Detecting oriented targets in remote sensing images amidst complex and heterogeneous backgrounds remains a formidable challenge in the field of object detection.Current frameworks for oriented detection modules are constrained by intrinsic limitations,including excessive computational and memory overheads,discrepancies between predefined anchors and ground truth bounding boxes,intricate training processes,and feature alignment inconsistencies.To overcome these challenges,we present ASL-OOD(Angle-based SIOU Loss for Oriented Object Detection),a novel,efficient,and robust one-stage framework tailored for oriented object detection.The ASL-OOD framework comprises three core components:the Transformer-based Backbone(TB),the Transformer-based Neck(TN),and the Angle-SIOU(Scylla Intersection over Union)based Decoupled Head(ASDH).By leveraging the Swin Transformer,the TB and TN modules offer several key advantages,such as the capacity to model long-range dependencies,preserve high-resolution feature representations,seamlessly integrate multi-scale features,and enhance parameter efficiency.These improvements empower the model to accurately detect objects across varying scales.The ASDH module further enhances detection performance by incorporating angle-aware optimization based on SIOU,ensuring precise angular consistency and bounding box coherence.This approach effectively harmonizes shape loss and distance loss during the optimization process,thereby significantly boosting detection accuracy.Comprehensive evaluations and ablation studies on standard benchmark datasets such as DOTA with an mAP(mean Average Precision)of 80.16 percent,HRSC2016 with an mAP of 91.07 percent,MAR20 with an mAP of 85.45 percent,and UAVDT with an mAP of 39.7 percent demonstrate the clear superiority of ASL-OOD over state-of-the-art oriented object detection models.These findings underscore the model’s efficacy as an advanced solution for challenging remote sensing object detection tasks.

Will lithium-sulfur batteries be the next beyond-lithium ion batteries and even much better?

Lithium-ion batteries(LIBs)are undoubtedly the current working-horse in almost all portable electronic devices,electric vehicles,and even large-scale stationary energy storage.Given the problems faced by LIBs,a big question arises as to which battery(ies)would be the“Beyond LIBs”batteries.Among the front-runners,lithium-sulfur batteries(LSBs)have been extensively pursued owing to their intrinsically high energy density and extremely low cost.Despite the steady and sometimes exciting progress reported on sulfur chemistry and cell performance at laboratory scales over the past decade,one of the major bottlenecks is the poor cyclability.In this perspective,we examine the key challenges and opportunities faced by LSBs,as well as approaches at the materials,electrode/electrolyte and cell integration levels that can be taken to transform LSBs from a front-runner to a real leading champion in the pursuit of the“Beyond LIBs”.While the key new mechanistic insights are very important,we propose a set of the near-future research directions for both the liquid and solid state LSBs,where the currently on-going parallel pursuits of both liquid and solid LSBs will be converging.The“liquid current”will gradually be taken over by“solid future”in the expected LSBs commercialization in the coming decade.

Wide-pH-range adaptable ammonia electrosynthesis from nitrate on Cu-Pd interfaces

Ammonia production via electrochemical nitrate reduction is essential for environmental protection and the emerging hydrogen economy. Complex nitrate wastewater with a wide pH range calls for flexible catalysts with high selectivity. A high Faradaic efficiency(FE) of NH3 cannot be obtained under strong acid or alkaline conditions due to the uncontrollable adsorption energy and coverage of hydrogen species(H*) on active sites. This article describes the design and fabrication of a copper-palladium(Cu-Pd) alloy nanocrystal catalyst that inhibits H2 and nitrite generation in electrolytes with different nitrate concentrations and varied pH. The interfacial sites of Cu-Pd alloys could enhance the adsorption energy and coverage of H* while increasing the reaction rate constant of NO_(2)*-to-NO*, which achieves a rapid conversion of NO_(2)* along with a decreased FE of NO_(2)-. Under ambient conditions, optimal FE(NH3) is close to 100% at a wide pH range, with the solar-to-chemical conversion efficiency approaching 4.29%. The combination of thermodynamics and kinetics investigations would offer new insights into the reduction mechanism of NO_(2)* for further development of nitrate reduction.

Towards a scientific rationale for traditional properties of Chinese medicinal plants: “natures” and “flavors”

Objective: According to theory of Chinese medicine property, the ecological environment shapes properties(natures and flavors) of Chinese materia medica(CMM) and there are close relationships between certain natures and flavors. However, to date these observations have not been validated scientifically in the context of the whole flora of a region. The present study aims to address this gap.Methods: We collected geographical distributions of 3637 vascular plant species native to the Xinjiang region of northwest China, of which around 812 are medicinal plants. The CMM property characters of these medicinal plants were also collected. All medicinal plants were then analyzed in the occurrence of their natures(cold, cool, neutral, warm, and hot) and flavors(sweet, bitter, sour, salty, and pungent). Possible correlations between these properties and environmental factors, notably climate, as well as correlations with plant species richness of the wider native flora of Xinjiang were then investigated using permutation test and regression.Results: Cold species(38.5%) were more numerous than warm(21.0%) and neutral(22.3%), while bitter species(43.3%) were more numerous than pungent(25.6%), sweet(22.4%) and sour(6.7%) ones. Species with bitter flavor were most commonly also cold(48.6%) in nature, sour flavor usually coincided with cold(44.2%) or cool nature(26.0%), whereas pungent or sweet species tended to be warm(34.4%, 28.4%) or neutral(27.8%, 28.4%). The percentages of species of cold/cool nature, bitter flavor were higher in mountainous regions, and the percentages of warm/neutral and pungent/sweet/sour were higher in basins. The percentages of species of cold/cool, bitter were positively correlated with actual evapotranspiration(AET),and also plant species richness but had a bell-shaped relationship with potential evapotranspiration(PET),whereas the inverse situation was shown for warm/neutral and pungent/sweet/sour species.Conclusion: Analysis of the data in Xinjiang region of China supports the qualitative observations concerning natures and flavors in traditional theory of Chinese medicine property. Specifically,(i) certain natures and flavors co-occur more frequently than if randomly distributed;(ii) correlations between proportions of natures and flavors and climatic variables suggest a role for the environment in shaping the properties of CMM.