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Quantification of perfluorinated compounds in atmospheric particulate shows potential connection with environmental event

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Journal of Environmental Sciences 2024年第2期136卷 237-247页

作者： Hua Tang Ying Wang Shengling Si Hongli Li david da Yong Chen National institute of Metrology 18 BeisanhuandongluChaoyang DistrictBeijing 100029China School of Chemistry and Materials Science Nanjing Normal UniversityNanjing 210023China Si Chuan zhong Ce Biao Wu Technology Co.Ltd. Sichuan 610052China Department of Chemistry University of British ColumbiaVancouver V6T 1Z1BCCanada

A method of quantification of perfluorinated compounds(PFCs)from atmospheric particulate matter(APM)is described.A single step pretreatment method,selective pressurized liquid extraction(SPLE),was developed to reduce the high matrix background and avoid contamination from commonly used multiple sample pretreatment *** effective sorbent was selected to purify the PFCs during SPLE,followed by liquid chromatography-tandem mass spectrometry(LC–MS/MS),for quantification of *** affecting the SPLE efficiency,including temperature,static extraction time,and number of extraction cycles used,were *** optimum conditions were found to be 120℃,10 min,and 3 cycles,***-MS/MS method was developed to obtain the optimal sensitivity specific to *** method detection limits(MDLs)were 0.006 to 0.48 ng/g for the PFCs studied and the linear response range was from 0.1 to 100 ng/*** ensure accurate values were obtained,each step of the experiment was evaluated and controlled to prevent *** optimized method was tested by performing spiking experiments in natural particulate matter matrices and good rates of recovery and reproducibility were obtained for all target ***,the method was successfully used to measure 16 PFCs in the APM samples collected in Beijing over five years from 2015 to *** is observed that some PFCs follow the trend of total PFC changes,and can be attributed to the environment influencing events and policy enforcement,while others don't seem to change as much with time of the year or from year to year.

关键词： Selective pressurized liquid extraction Liquid chromatography-mass spectrometry Perfluorinated compounds Atmospheric particulate matter Pollution control

Local search yields a PTAS for fixed-dimensional k-means problem with penalties

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Journal of the Operations Research Society of China 2024年第2期12卷 351-362页

作者： Fan Yuan da-Chuan Xu Dong-Lei Du Dong-Mei zhang Beijing institute for Scientific and Engineering Computing Beijing University of TechnologyBeijing 100124China Faculty of Management University of New BrunswickFrederictonNB E3B 9Y2Canada School of Computer Science and Technology Shandong Jianzhu UniversityJinan 250101ShandongChina

We study a problem called the k-means problem with penalties(k-MPWP),which is a natural generalization of the typical k-means *** this problem,we have a set D of client points in R^(d),a set F of possible centers in R^(d),and a penalty cost Pj>O for each point j∈*** are also given an integer k which is the size of the center point *** want to find a center point set S■F with size k,choose a penalized subset of clients P■D,and assign every client in D\P to its open *** goal is to minimize the sum of the squared distances between every point in D\P to its assigned centre point and the sum of the penalty costs for all clients in *** using the multi-swap local search technique and under the fixed-dimensional Euclidean space setting,we present a polynomial-time approximation scheme(PTAS)for the k-MPWP.

关键词： Approximation algorithm k-means Local search Penalty

znO/CeO_(2)/carbon xerogel composites with direct z-scheme heterojunctions:Enhancing photocatalytic remediation of 4-chlorophenol under visible light

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Journal of Rare Earths 2024年第2期42卷 314-322,I0003页

作者： Nicolas Perciani de Moraes Maite Birkett de Campos Sanmartin Robson da Silva Rocha Abner de Siervo Marcos Roberto de Vasconcelos Lanza D.Amaranatha Reddy Lianqing Yu Liana Alvares Rodrigues Escola de Engenharia de Lorena-EEL/USP Estrada Municipal do Campinho S/NCEP 12602-810LorenaSao PauloBrazil institute of Physics"Gleb Wataghin" Applied Physics DepartmentState University of Campinas13083-859CampinasSPBrazi instituto de Quimica de Sao Carlos Universidade de Sao PauloAv.Trab.Sao Carlense400-Parque Arnold SchimidtSao CarlosSP13566-590Spain Department of Sciences Indian Institute of Information Technology Design and ManufacturingKurnoolAndhra Pradesh518007India School of Materials Science and Engineering China University of PetroleumQingdao266580China

This paper aims to create visible light driven ternary photocatalysts using zinc oxide(znO),cerium(iV)oxide(CeO_(2)),and carbon xerogel(CX) as constituent *** use of CeO_(2) is based on the creation of direct-z-scheme heterojunctions with the znO and the consequent diminishing of charge recombination,whereas the carbon xerogel inclusion is predicted to minimize bandgap energy,decrease electro n-hole reco mbination,and boost specific surface *** re,the choice of the black-wattle tannin as a carbonaceous precursor was targeted at the development of an environmentally friendly and affordable *** existence of the hexagonal phase of zinc oxide and cubic structure of the cerium(iV) oxide in the ternary material was confirmed by X-ray diffractometry and X-ray photoelectron spectroscopy,with the latter also suggesting chemical bonding between the znO and the CX due to the creation of zinc oxycarbide *** inclusion of the carbon xerogel provokes a significant modification in the morphology of the ternary material,resulting in an increased surface area and smaller particle *** CX/znO-CeO_(2) ternary composite obtains the highest photocatalytic efficiency among all the materials studied,degrading 100% of 4-chlorophenol under simulated sunlight and 68% under visible radiation,after 5 *** increased photocatalytic activity can be attributed to the formation of direct z-scheme heterojunctions between the semiconductors,higher visible light response,and higher specific surface area,as evidenced by the results obtained by active radical scavenging,chronoamperometry,diffuse reflectance spectroscopy,and N_(2) adsorption-desorption isotherms.

关键词： zinc oxide Cerium(Ⅳ)oxide Carbon xerogel Photocatalysis Direct z-scheme heterojunction 4-Chlorophenol Rare earths

SHEL:a semantically enhanced hardware-friendly entity linking method

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High Technology Letters 2024年第1期30卷 13-22页

作者：亓东林 CHEN Shudong DU Rong TONG da YU Yong institute of Microelectronics of Chinese Academy of Sciences Beijing 100029P.R.China University of Chinese Academy of Sciences Beijing 100190P.R.China

With the help of pre-trained language models,the accuracy of the entity linking task has made great strides in recent ***,most models with excellent performance require fine-tuning on a large amount of training data using large pre-trained language models,which is a hardware threshold to accomplish this *** researchers have achieved competitive results with less training data through ingenious methods,such as utilizing information provided by the named entity recognition *** paper presents a novel semantic-enhancement-based entity linking approach,named semantically enhanced hardware-friendly entity linking(SHEL),which is designed to be hardware friendly and efficient while maintaining good ***,SHEL's semantic enhancement approach consists of three aspects:(1)semantic compression of entity descriptions using a text summarization model;(2)maximizing the capture of mention contexts using asymmetric heuristics;(3)calculating a fixed size mention representation through pooling *** series of semantic enhancement methods effectively improve the model's ability to capture semantic information while taking into account the hardware constraints,and significantly improve the model's convergence speed by more than 50%compared with the strong baseline model proposed in this *** terms of performance,SHEL is comparable to the previous method,with superior performance on six well-established datasets,even though SHEL is trained using a smaller pre-trained language model as the encoder.

关键词： entity linking(EL) pre-trained models knowledge graph text summarization semantic enhancement

Visible Light-induced Collapse of Molecular Microcrystals into Droplets by E-to-z Photoisomerization and Melting Phase Transition

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CCS Chemistry 2024年第4期6卷 1071-1084页

作者： Tian-Yi Xu Min Cui Chengxi zhao Shang-Wu zhou Tian-Le zhang Hui-Yao Lin Fei Tong da-Hui Qu Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237

Harnessing photoresponsive behavior in organic crystals,such as shape and morphology deformation,on multiple scales is intriguing with respect to precise spatiotemporal operation,because dynamic deformations are promising in fabricating future intelligent ***,we synthesized a new photoresponsive molecular crystal composed of dimethyl(E)-2-(3-(naphthalen-1-yl)allylidene)malonate((E)-DNAM)that undergoes E-to-z photoisomerization accompanied by photoinduced crystal-to-liquid melting phase transition when exposed to visible *** of expanding in bulk polycrystals,single-crystal(E)-DNAM rectangular microplates in an aqueous solution rapidly collapsed into liquid droplets,showing a remarkable drastic reduction in surface area of more than 97%after light *** deduce that the unique microscopic morphology of microplates with high aspect ratios of length-tothickness reaching up to 1000 is mainly responsible for the photoinduced melting leading to drastic *** addition,the cohesive forces of liquid photoproduct facilitate the overall deformations and *** have shown a facile way to achieve the remarkable collapse of molecular crystals into droplets by photochemical reaction and phase transition.

关键词： molecular crystals crystal-to-liquid transition extreme deformations photochemistry crystal engineering flexible crystals

Hyperbolic hierarchical graph attention network for knowledge graph completion

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High Technology Letters 2024年第3期30卷 271-279页

作者： XU Hao CHEN Shudong Qi Donglin TONG da YU Yong CHEN Shuai institute of Microelectronics of Chinese Academy of Sciences Beijing 100029P.R.China University of Chinese Academy of Sciences Beijing 100049P.R.China

Utilizing graph neural networks for knowledge embedding to accomplish the task of knowledge graph completion(KGC)has become an important research area in knowledge graph ***,the number of nodes in the knowledge graph increases exponentially with the depth of the tree,whereas the distances of nodes in Euclidean space are second-order polynomial distances,whereby knowledge embedding using graph neural networks in Euclidean space will not represent the distances between nodes *** paper introduces a novel approach called hyperbolic hierarchical graph attention network(H2GAT)to rectify this ***,the paper conducts knowledge representation in the hyperbolic space,effectively mitigating the issue of exponential growth of nodes with tree depth and consequent information ***,it introduces a hierarchical graph atten-tion mechanism specifically designed for the hyperbolic space,allowing for enhanced capture of the network structure inherent in the knowledge ***,the efficacy of the proposed H2GAT model is evaluated on benchmark datasets,namely WN18RR and FB15K-237,thereby validating its *** H2GAT model achieved 0.445,0.515,and 0.586 in the Hits@1,Hits@3 and Hits@10 metrics respectively on the WN18RR dataset and 0.243,0.367 and 0.518 on the FB15K-237 *** incorporating hyperbolic space embedding and hierarchical graph attention,the H2GAT model successfully addresses the limitations of existing hyperbolic knowledge embedding models,exhibiting its competence in knowledge graph completion tasks.

关键词： hyperbolic space link prediction knowledge graph embedding knowledge graph completion(KGC)

Preliminary Application of High-Frequency Ultrasound in the Differentiation of Pemphigus and Bullous Pemphigoid: An Observational Study

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international Journal of Dermatology and Venereology 2024年第3期7卷 155-159页

作者： Liu Y.-A. Cao R. da M.-H. Dong z.-B. Wang F. Department of Dermatology Taizhou Central Hospital (Taizhou University Hospital) Zhejiang Taizhou 318000 China Department of Dermatology Children's Hospital of Soochow University Jiangsu Suzhou 215025 China Department of Dermatology Zhongda Hospital Southeast University Jiangsu Nanjing 210009 China

Objective: Ultrasonography is a diagnostic imaging technique used to visualize subcutaneous body structures for identification of possible pathologies. in this study, we aimed to explore the clinical significance of high-frequency ultrasound in differentiating the location of blisters between pemphigus and bullous pemphigoid. Methods: Eighteen patients were recruited in Department of Dermatology, zhongda Hospital from 2020 to 2021 and divided into a pemphigus group (n = 8) and a bullous pemphigoid group (n = 10) according to the diagnostic criteria for each. Ultrasonographic images were collected using a 50-MHz high-frequency ultrasound system. The indexes of ultrasonic evaluation were the layer (epidermis or dermis), size, shape, internal echo, and boundary of the blister. Categorical variables are expressed as n (%), and differences were compared using Fisher's exact test. Results: The ultrasonographic images in the pemphigus group showed an intraepidermal semi-arc or irregular anechoic or hypoechoic areas. The inferior borders were situated above the characteristic thin linear hyperechoic bands of the epidermis. A linear hypoechoic band was present at the dermoepidermal junction in some cases. in the ultrasonographic images of the bullous pemphigoid group, the linear hyperechoic bands of the epidermis were continuous and intact. An oval fluid anechoic area (subepidermal blister) was present immediately below the bands. The location of the blisters in the ultrasonographic images was significantly different between the 2 groups (P ion: High-frequency ultrasound can be used as an auxiliary means to differentiate the location of blisters between pemphigus and bullous pemphigoid. © 2022 Hospital for Skin Diseases (institute of Dermatology), Chinese Academy of Medical Sciences, and Chinese Medical Association, published by Wolters Kluwer, inc.

关键词： bullous pemphigoid high-frequency ultrasound pemphigus

High-Quality and Wafer-Scale Cubic Silicon Carbide Single Crystals

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Energy & Environmental Materials 2024年第4期7卷 442-449页

作者： Guobin Wang da Sheng Yunfan Yang Hui Li Congcong Chai zhenkai Xie Wenjun Wang Jiangang Guo Xiaolong Chen Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

Cubic silicon carbide (3C-SiC) has superior mobility and thermal conduction over that of widely applied hexagonal ***,much lower concentration of interfacial traps between insulating oxide gate and3C-SiC helps fabrica... 详细信息

关键词： cubic SiC high-temperature solution growth high-temperature surface tension solid–liquid interfacial energy wide band gap semiconductor

Microstructure development of Ti scaffold by laser powder bed fusion with chemical polishing and its mechanical properties, biocompatibility

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BiOSURFACE AND BiOTRiBOLOGY 2024年第2期10卷 52-62页

作者： Lu, Changfu Chen, Jing Ma, Teng Chen, Yuxin zeng, da Gan, Yiliang Yang, Youwen Double Med Technol inc Xiamen Peoples R China Jiangxi Univ Sci & Technol Inst Addit Mfg Nanchang Peoples R China Tongling Univ Key Lab Construct Hydraul Robots Anhui Higher Educ Tongling Peoples R China Nanjing Univ Coll Engn & Appl Sci Nanjing Peoples R China

Titanium (Ti) dental scaffolds are widely used in dental prosthetics due to their excellent mechanical properties and biocompatibility. However, conventional Ti scaffolds manufactured through machining often do not fit perfectly with the bone defect site. Laser powder bed fusion (LPBF) technology enables the personalised manufacturing of custom-made Ti scaffolds. A custom-made Ti scaffold was prepared using LPBF and its surface roughness was improved through chemical polishing. To enhance the surface roughness, a nitric acid mixed solution with a specific composition of HF: HNO3:C3H6O3 = 2:2:3 was used. The polishing mechanism was investigated by adjusting the F/Ti ratio to control the formation and dissolution of the oxide film. As a result, the surface of the Ti scaffold after polishing exhibited a smooth and flat appearance compared to the LPBF part, with a reduced surface roughness (Ra) of 1.23 +/- 0.19 mu m. The custom-made Ti scaffold also demonstrated favourable mechanical properties, with a bending strength of 335.18 +/- 33.62 MPa and stiffness of 2.13 +/- 0.21 GPa. Furthermore, in vitro cell tests confirmed the excellent biocompatibility of the custom-made Ti scaffold. The authors present a feasible strategy for the further clinical application of custom-made Ti scaffolds, offering enhanced surface properties and addressing the limitations of conventional machining methods.

关键词： additive manufacturing dental material property surface roughness GUiDED BONE REGENERATiON ALLOY OPTiMizATiON PARAMETERS MEMBRANE BEHAViOR