Strongly Coupled Ag/Sn-SnO_(2)Nanosheets Toward CO_(2)Electroreduction to Pure HCOOH Solutions at Ampere‑Level Current

Electrocatalytic reduction of CO_(2) converts intermittent renewable electricity into value-added liquid products with an enticing prospect,but its practical application is hampered due to the lack of high-performance electrocatalysts.Herein,we elaborately design and develop strongly coupled nanosheets composed of Ag nanoparticles and Sn-SnO_(2) grains,designated as Ag/Sn-SnO_(2) nanosheets(NSs),which possess optimized electronic structure,high electrical conductivity,and more accessible sites.As a result,such a catalyst exhibits unprecedented catalytic performance toward CO_(2)-to-formate conversion with near-unity faradaic efficiency(≥90%),ultrahigh partial current density(2,000 mA cm^(−2)),and superior long-term stability(200 mA cm^(−2),200 h),surpassing the reported catalysts of CO_(2) electroreduction to formate.Additionally,in situ attenuated total reflection-infrared spectra combined with theoretical calculations revealed that electron-enriched Sn sites on Ag/Sn-SnO_(2)NSs not only promote the formation of*OCHO and alleviate the energy barriers of*OCHO to*HCOOH,but also impede the desorption of H*.Notably,the Ag/Sn-SnO_(2)NSs as the cathode in a membrane electrode assembly with porous solid electrolyte layer reactor can continuously produce~0.12 M pure HCOOH solution at 100 mA cm^(−2)over 200 h.This work may inspire further development of advanced electrocatalysts and innovative device systems for promoting practical application of producing liquid fuels from CO_(2).

Advances in depressants for flotation separation of Cu–Fe sulfide minerals at low alkalinity:A critical review

The flotation separation of Cu–Fe sulfide minerals at low alkalinity can be achieved using selective depressants.In the flotation system of Cu–Fe sulfide minerals,depressants usually preferentially interact with the pyrite surface to render the mineral surface hydrophilic and hinder the adsorption of the collector.This review summarizes the advances in depressants for the flotation separation of Cu–Fe sulfide minerals at low alkalinity.These advances include use of inorganic depressants (oxidants and sulfur–oxygen compounds),natural polysaccharides (starch,dextrin,konjac glucomannan,and galactomannan),modified polymers (carboxymethyl cellulose,polyacrylamide,lignosulfonate,and tricarboxylate sodium starch),organic acids (polyglutamic acid,sodium humate,tannic acid,pyrogallic acid,salicylic acid,and lactic acid),sodium dimethyl dithiocarbamate,and diethylenetriamine.The potential application of specific inorganic and organic depressants in the flotation separation of Cu–Fe sulfide minerals at low alkalinity is reviewed.The advances in the use of organic depressants with respect to the flotation separation of Cu–Fe sulfide minerals are comprehensively detailed.Additionally,the depression performances and mechanisms of different types of organic depressants on mineral surfaces are summarized.Finally,several perspectives on depressants vis-à-vis flotation separation of Cu–Fe sulfide minerals at low alkalinity are proposed.

Enhanced sulfidization flotation of cuprite by surface modification with hydrogen peroxide

Hydrogen peroxide was used as an oxidant to modify the cuprite surface and enhance its sulfidization.Surface-adsorption and infrared spectroscopy measurements indicated that the modification of the cuprite surface with hydrogen peroxide before sulfidization increased the adsorption capacity of xanthate.Zeta potential,scanning electron microscopy-energy dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,and time-of-flight secondary ion mass spectrometry results showed that the modification with hydrogen peroxide increased the contents of S^(2−)and Sn^(2−)species on the cuprite surface.Microflotation tests showed that the recovery of cuprite increased from 61.74%to 83.30%after the modification of the surface with hydrogen peroxide.These results confirm that the modification of the cuprite surface with hydrogen peroxide enhances the sulfidization of cuprite,which in turn improves its flotation.

Adsorption behavior and mechanism of copper ions in the sulfidization flotation of malachite

Malachite is one of the main minerals used for the industrial enrichment and recovery of copper oxide resources, and copper ions are unavoidable metal ions in the flotation pulp. The microflotation, contact angle, and adsorption experiments indicated that pretreatment with an appropriate concentration of copper ions could improve the malachite recovery, and the addition of excess copper ions reduced the hydrophobicity of the malachite surface. The results of zeta potential tests indicated that sodium sulfide and butyl xanthate were also adsorbed on the surface of malachite pretreated with copper ions. X-ray photoelectron spectroscopy(XPS) results indicated that —Cu—O and —Cu—OH bonds were formed on the surface of the samples. After pretreatment with an appropriate concentration of copper ions, the number of —OH groups on the mineral surface decreased, whereas the number of Cu—S groups on the mineral surface increased, which was conducive to the sulfidization of malachite. After adding a high concentration of copper ions, the —OH groups on the mineral surface increased, whereas the number of Cu—S groups decreased, which had an adverse effect on the sulfidization flotation of malachite. Time-of-flight secondary ion mass spectrometry showed that pretreatment with copper ions resulted in a thicker sulfidization layer on the mineral surface.

A mechanism for the origin and development of the large-scale dunefield on the right flank of the lower reach of Laoha River,Northeast China

By viewing satellite imagery, a striking large-scale dunefield can be clearly perceived, with a size of nearly 63 km long and 11 km wide, and trending NE-SW, on the right flank of the lower Laoha River, Northeast China. By means of remote sensing imagery analysis and field observation as well as a comparison with a small-scale dunefield on the right flank of the lower Xiangshui River, analogous to the case of the lower Laoha River, this paper presents a new mechanism for its origin and development. The results show that： （1） the large-scale dunefield bears a tile-style framework overwhelmingly composed of transverse barchanoid ridges perpendicular to the predominant winds, and inlaid diverse blowouts. （2） The small-scale dunefield, referred to as a primary structural unit of the large one, is typical of an incipient dunefield, following the same rules of evolution as the larger. （3） A succession of barchanoid ridge chains can steadily migrate downwind in much the same manner as surface wave propagation in air or water stimulated by an incised valley, and ultimately tend to bear roughly the same wavelength and amplitude under stable climate and hydrologic regimes. （4） The first ridge chain acquires its sand source substantially from the downwind escarpments exposing the loose Quaternary sandy sediments to the air, while the ensuing ridges derive their sands dominantly from in situ deflation of the underlain Quaternary loose sandy sediments in blowouts, partly from the upwind ridges through northern elongated horns. Theoretically, the sands from riparian escarpments can be transported by wind to the downwind distal end of a dunefield after sufficient long du- ration. （5） The lower Laohahe region experienced probably three significant climatic changes in the past, corresponding to the three active dune belts, suggesting that once a large-scale dunefield occurs, it is nearly impossible to be completely stabilized, at least in its central portions. At present, seasonal shrinkage and stagnation of the lower Laoha River, wide-spread farming and afforestation in the valley, and establishing windbreaks downwind of the valley as well as surrounding the dunefield, appear to have significantly modified local flow fields and sand sources, engendering significant degradation of the dunefield.

Magnesium-based energy materials: Progress, challenges, and perspectives

Magnesium-based energy materials, which combine promising energy-related functional properties with low cost, environmental compatibility and high availability, have been regarded as fascinating candidates for sustainable energy conversion and storage. In this review,we provide a timely summary on the recent progress in three types of important Mg-based energy materials, based on the fundamental strategies of composition and structure engineering. With regard to Mg-based materials for batteries, we systematically review and analyze different material systems, structure regulation strategies as well as the relevant performance in Mg-ion batteries(MIBs) and Mg-air batteries(MABs), covering cathodes, electrolytes, anodes for MIBs, and anodes for MABs;as to Mg-based hydrogen storage materials, we discuss how catalyst adding, composite, alloying and nanostructuring improve the kinetic and thermodynamic properties of de/hydrogenation reactions, and in particular, the impacts of composition and structure modification on hydrogen absorption/dissociation processes and free energy modification mechanism are focused;regarding Mg-based thermoelectric materials, the relations between composition/structure and electrical/thermal transport properties of Mg_(3)X_(2)(X = Sb, Bi), Mg_(2)X(X = Si, Ge, Sn) and Mg Ag Sb-based materials, together with the representative research progress of each material system, are summarized and discussed. Finally, by pointing out remaining challenges and providing possible solutions, this review aims to shed light on the directions and perspectives for practical applications of magnesium-based energy materials in the future.

Realizing Cd and Ag codoping in p-type Mg_(3)Sb_(2)toward high thermoelectric performance

Mg_(3)Sb_(2)has attracted intensive attention as a typical Zintl-type thermoelectric material.Despite the exceptional thermoelectric performance in n-type Mg_(3)Sb_(2),the dimensionless figure of merit(zT)of p-type Mg_(3)Sb_(2)remains lower than 1,which is mainly attributed to its inferior electrical properties.Herein,we synergistically optimize the thermoelectric properties of p-type Mg_(3)Sb_(2)materials via codoping of Cd and Ag,which were synthesized by high-energy ball milling combined with hot pressing.It is found that Cd doping not only increases the carrier mobility of p-type Mg_(3)Sb_(2),but also diminishes its thermal conductivity(κ_(tot)),with Mg_(2.85)Cd_(0.5)Sb_(2)achieving a lowκtot value of∼0.67 W m^(−1)K^(−1)at room temperature.Further Ag doping elevates the carrier concentration,so that the power factor is optimized over the entire temperature range.Eventually,a peak zT of∼0.75 at 773 K and an excellent average zT of∼0.41 over 300−773 K are obtained in Mg_(2.82)Ag_(0.03)Cd_(0.5)Sb_(2),which are∼240%and∼490%higher than those of pristine Mg_(3.4)Sb_(2),respectively.This study provides an effective pathway to synergistically improve the thermoelectric performance of p-type Mg_(3)Sb_(2)by codoping Cd and Ag,which is beneficial to the future applications of Mg_(3)Sb_(2)-based thermoelectric materials.

Roles of Cu doping in YbZn_(2)Sb_(2) for thermoelectric performance enhancement

Recent research shows that increasing the carrier density after orbital alignment in AZn_(2)Sb_(2) (A=Ca,Yb,Eu,Sr,Mg)Zintl compounds yields remarkable results with regard to enhanced thermoelectric performance.However,research on carrier density increase via doping in these compounds is limited.In this study,we introduced Cu into the Zn sites in YbZn_(2)Sb_(2) and examined the thermoelectric properties.

局部晚期鼻咽癌患者营养状况及其与预后相关性分析

目的:探讨局部晚期鼻咽癌患者营养状况及其与预后相关性。方法:分析2015年8月至2017年3月湖北省肿瘤医院收治的局部晚期鼻咽癌住院患者53例,联合运用患者主观整体营养评估量表(patient-generated subjective global assessment,PGSGA)、体格测量、血液学指标和放化疗不良反应,全面评估患者营养状况;采用Kaplan-Meier法及Cox风险比例回归模型对患者生存及影响因素进行分析。结果:53例患者中,94.3%(50/53)的患者出现体质量下降,下降均值为(6.89±0.54)kg,50.9%(27/53)的患者体质量下降≥10%;PG-SGA评估的患者重度营养不良发生率为84.9%(45/53);淋巴细胞计数、红细胞、血红蛋白、白蛋白与PG-SGA评分高度负相关(P<0.05),口腔黏膜炎、吞咽困难或疼痛、厌食、体质量下降百分比与PG-SGA评分高度正相关(P<0.05);单因素及多因素分析显示,TNM分期晚、治疗期间体质量下降≥10%与局部晚期鼻咽癌患者预后不良相关,而白细胞计数增加(在正常值范围内)与局部晚期鼻咽癌患者预后良好相关,差异均具有统计学意义(P=0.036,P=0.016,P=0.024)。结论:局部晚期鼻咽癌患者营养不良发生率高;PG-SGA评分联合体格测量、血液学指标和放化疗不良反应,能够更全面地评估患者营养状况;TNM分期晚、治疗期间体质量下降≥10%是局部晚期鼻咽癌患者预后的不良因素,而白细胞计数增加(在正常值范围内)是患者预后的有利因素。

我国高校城市规划专业人才培养中存在的主要问题及其对策研究

新型城市化对城市规划专业人才的需求提出了更高的要求,作为专业人才培养主体的高校应积极应对这种变化。本文通过对代表性“985”及“211”高校的培养目标、专业设立背景、课程设置的现状等方面的系统分析,指出了我国现阶段大部分高校的课程设置偏重于建筑学课程的设置,而忽略了地理学及生态学课程的开设与强化,难以适应新形势发展需要的基本事实,认为修订培养方案与教学计划是当务之急。本文建议:1) 在总课时不变的情况下,适度减少建筑学专业课的数量和课时,为开设生态学和地理学课程提供必要的课时;2) 建立多元化生态学和地理学课程的开设课程体系,即生态学和地理学课程的开设要必修和选修、概论课与分论课结合,使之形成一个完整的课程体系;3) 建立相配套的具有扎实专业知识背景和实践经验的专业教师队伍。

Flotation of copper oxide minerals:A review

Copper oxide minerals are important copper resources,which include malachite,azurite,chrysocolla,cuprite,etc.Flotation is the most widely used method for the enrichment of copper oxide minerals in the mineral processing industry.In this paper,the surface properties of copper oxide minerals and their effects on the mineral flotation behavior are systematically summarized.The flotation methods of copper oxide minerals and the interaction mechanism with reagents are reviewed in detail.Flotation methods include direct flotation(using chelating reagents or a fatty acid as collector),sulfidization flotation(using xanthate as collector),and activation flotation(using chelating reagents,ammonium/amine salts,metal ions,and oxidant for activation).An effective way to realize efficient flotation of copper oxide minerals is to increase active sites on the surface of copper oxide minerals to enhance the interaction of collector with the mineral surface.Besides,various perspectives for further investigation on the efficient recovery of copper oxide minerals are proposed.

Sulfidization regulation of cuprite by pre-oxidation using sodium hypochlorite as an oxidant

The direct sulfidization of cuprite is inefficient because cuprite is a copper-oxide mineral with a strong surface hydrophilicity.In this study,oxidant was used to modify cuprite surfaces to regulate the sulfidization of cuprite.Microflotation tests showed that the flotation recovery of pre-oxidized cuprite was nearly25% higher than that of direct sulfidization flotation,which indicates that the cuprite surface activity was enhanced after pre-oxidation by Cu(Ⅰ) species(weak affinity with sulfur ions) transformation to Cu(Ⅱ)species(strong affinity with sulfur ions).Zeta potential,scanning electron microscopy-energy dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,and time-of-flight secondary ion mass spectrometry results showed that pre-oxidation improved cuprite sulfidization and promoted the formation of copper-sulfide species on the cuprite surfaces.The mineral surface stability and thus,xanthate species adsorption on the cuprite surfaces were improved.The surface-adsorption measurements and infrared spectroscopy showed that a large amount of xanthate species was adsorbed onto the sulfidized cuprite surfaces after pre-oxidation,which enhanced the cuprite hydrophobicity and improved the cuprite flotation.

PhaseⅡstudy of induction chemotherapy followed by concurrent chemoradiotherapy with raltitrexed and cisplatin in locally advanced nasopharyngeal carcinoma

Objective:For locally advanced nasopharyngeal carcinoma(LA-NPC)patients,high incidences of distant metastases and severe treatment related toxicities are the main obstacles needed to be overcome.Raltitrexed,a specific thymidylate synthase inhibitor with a convenient administration schedule,has an acceptable and manageable toxicity,and possesses radio-sensitizing properties.To investigate the efficacy and safety of raltitrexed and cisplatin induction chemotherapy and concurrent chemoradiotherapy(IC+CCRT)in patients with LA-NPC,a phaseⅡclinical study was conducted.Methods:Sixty eligible patients with LA-NPC were enrolled into this study.A raltitrexed-cisplatin combination was used as part of an IC+CCRT regimen.Raltitrexed-cisplatin IC was given once every 3 weeks(q3 w)for two cycles,followed by raltitrexed-cisplatin based CCRT q3 w for two cycles.Intensity-modulated radiotherapy(IMRT)was given for all enrolled patients.Results:All patients were included in survival analysis according to the intent-to-treat principle.The objective response rate(ORR)3 months after treatment was 98%.The 2-year overall survival(OS)rate was 92%.The median relapse-free survival(RFS)time was 30.5[95%confidence interval(95%CI),28.4-32.3]months.The 2-year RFS rate was 85%.The 2-year local failure-free survival(LFFS)rate was 97%and the 2-year distant metastasis-free survival(DMFS)rate was 88%.Acute toxicities were mostly grade 2 and 3 reactions in bone marrow suppression,gastrointestinal side effect and oropharyngeal mucositis.Only two patients occurred grade 4 acute toxicities,one was bone marrow suppression and the other was dermatitis radiation.Conclusions:The combination of raltitrexed and cisplatin has a comparable efficacy to those in standard firstline therapy.

High-performance magnesium-based thermoelectric materials:Progress and challenges

Magnesium-based materials have been regarded as promising candidates for large-scale,high-efficiency thermoelectric applications,owing to their excellent dimensionless figure of merit,high abundance,and low cost.In this review,we comprehensively summarize the recent advances of Mg-based thermoelectrics,including Mg_(2)X(X=Si,Ge,Sn),Mg3(Sb,Bi)_(2),andα-MgAgSb,from both material and device level.Their electrical and thermal transport properties are first elucidated based on the crystallographic characteristics,band structures,and phonon dispersions.We then review the optimization strategies towards higher thermoelectric performance,as well as the device applications of Mg-based thermoelectric materials and the related engineering issues.By highlighting the challenges and possible solutions in the end,this review intends to offer perspectives on the future research work to further enhance the performance of Mg-based materials for practical applications.

Holocene precipitationδ^18O as an indicator of temperature history in arid central Asia:an overview of recent advances

Holoceneδ^18O records from various archives(ice cores,cave stalagmites,and peat sediments)from the Xinjiang region of northwestern China,in arid central Asia(ACA),are all derived ultimately from local precipitationδ^18O(δ^18Op).Nevertheless,they have been proposed as indicators of different climatic parameters,such as wetness and temperature changes.This article summarizes previously reported records of moisture sources for the Xinjiang region and the results of modern observations conducted at an ice core site and a peat site in the Altai Mountains.The findings are used to propose that the overall positive trends in Holoceneδ^18O records from the various archives from the Xinjiang region primarily reflect the Holocene's long-term warming trend.It is concluded that more site-specific modern observations are needed to further elucidate the environmental significance of Holoceneδ^18O records from this region,especially for the separation of different seasonal temperature signals present withinδ^18O records.

A new insight into the promoting effects of transition metal phosphides in methanol electrooxidation

The construction of highly active catalysts for methanol oxidation reaction(MOR)is central to direct methanol fuel cells.Tremendous progress has been made in transition metal phosphides(TMPs)based catalysts.However,TMPs would be partially damaged and transformed into new substances(e.g.,Pt-M-P composite,where M represents a second transition metal)during Pt deposition process.This would pose a large obstacle to the cognition of the real promoting effects of TMPs in MOR.Herein,Co_(2)P co-catalysts(Pt-P/Co_(2)P@NPC,where NPC stands for N and P co-doped carbon)and Pt-Co-P composite catalysts(Pt-CoP/NPC)were controllably synthesized.Electrocatalysis tests show that the Pt-Co-P/NPC exhibits superior MOR activity as high as 1016 m A/mg_(Pt),significantly exceeding that of Pt-P/Co_(2)P@NPC(345 m A/mg_(Pt)).This result indicates that the promoting effect is ascribed primarily to the resultant Pt-Co-P composite,in sharply contrast to previous viewpoint that Co_(2)P itself improves the activity.Further mechanistic studies reveal that Pt-Co-P/NPC exhibits much stronger electron interaction and thus manifesting a remarkably weaker CO absorption than Pt-P/Co_(2)P@NPC and Pt/C.Moreover,Pt-Co-P is also more capable of producing oxygen-containing adsorbate and thus accelerating the removal of surface-bonded CO^(*),ultimately boosting the MOR performance.

异腈参与的多组分反应新进展

本文综述了异腈参与的多组分反应合成一些杂环化合物的最新研究进展,主要介绍了异腈参与的Ugi多组分反应的几种新型反应,详细地介绍了各种反应对底物的要求、反应条件、反应的选择性、产率以及机理的研究。同时对近年来发展的异腈参与的几种新型Passerini多组分反应进行了简单介绍。对异腈参与的多组分反应合成杂环化合物的前景进行了展望。

Rare Bird Sparse Recognition via Part-Based Gist Feature Fusion and Regularized Intraclass Dictionary Learning

Rare bird has long been considered an important in the field of airport security,biological conservation,environmental monitoring,and so on.With the development and popularization of IOT-based video surveillance,all day and weather unattended bird monitoring becomes possible.However,the current mainstream bird recognition methods are mostly based on deep learning.These will be appropriate for big data applications,but the training sample size for rare bird is usually very short.Therefore,this paper presents a new sparse recognition model via improved part detection and our previous dictionary learning.There are two achievements in our work:(1)after the part localization with selective search,the gist feature of all bird image parts will be fused as data description;(2)the fused gist feature needs to be learned through our proposed intraclass dictionary learning with regularized K-singular value decomposition.According to above two innovations,the rare bird sparse recognition will be implemented by solving one l1-norm optimization.In the experiment with Caltech-UCSD Birds-200-2011 dataset,results show the proposed method can have better recognition performance than other SR methods for rare bird task with small sample size.

Bismuth clusters pinned on TiO_(2) porous nanowires boosting charge transfer for CO_(2) photoreduction to CH_(4)

Artificial photosynthesis in carbon dioxide(CO_(2))conversion into value-added chemicals attracts considerable attention but suffers from the low activity induced by sluggish separation of photogenerated carriers and the kinetic bottleneck-induced unsatisfied selectivity.Herein,we prepare a new-style Bi/TiO_(2) catalyst formed by pinning bismuth clusters on TiO_(2) nanowires through being confined by pores,which exhibits high activity and selectivity towards photocatalytic production of CH_(4) from CO_(2).Boosted charge transfer from TiO_(2) through Bi to the reactants is revealed via in situ X-ray photon spectroscopy and time-resolved photoluminescence(PL).Further,in situ Fourier transform infrared results confirm that Bi/TiO_(2) not only overcomes the multi-electron kinetics challenge of CO_(2) to CH_(4) via boosting charge transfer,but also facilitates proton production and transfer as well as the intermediates*CHO and*CH_(3)O generation,ultimately achieving the tandem catalysis towards methanation.Theoretical calculation also underlies that the more favorable reaction step from*CO to*CHO on Bi/TiO_(2) results in CH_(4) production with higher selectivity.Our work brings new insights into rational design of photocatalysts with high performance and the formation mechanism of CO_(2) to CH_(4) for solar energy storage in future.

Synthesis-temperature-dependent phase composition manipulation toward high thermoelectric performance in tetrahedrites

Tetrahedrite,an Earth-abundant natural mineral,has attracted extensive research interest because of its excellent thermoelectric performance.Herein,tetrahedrite samples comprising Cu-poor Cu_(12)Sb_(4)S_(13)and Cu-rich Cu_(14)Sb_(4)S_(13)phases have been synthesized using a colloidal method,in which the ratio of two phases is manipulated by controlling the synthesis temperature to improve the thermoelectric perfor-mance.It is found that an ultralow total thermal conductivity of∼0.3 W m^(−1)K^(−1)at 723 K is realized in the sample with a Cu-rich phase fraction of∼50%,which can be attributed to maximized phonon scattering by phase boundaries.As a result,combined with a decent power factor,this sample obtains an optimal zT of 1.15,which is about 85%higher than that of the sample with a Cu-rich phase fraction of∼64%and comparable to zT values of other eco-friendly,abundant Cu-based thermoelectric materials.This work demonstrates an effective synthesis-temperature-dependent phase composition manipulation strategy toward enhanced thermoelectric performance in tetrahedrites.