从求助展演、情感共鸣到陌生互助——B站疾病求助类视频评论的情感分析

本文通过爬虫抓取了B站18个疾病求助视频的评论文本,进行文本分析、量化分析和多模态话语分析,探究网友对求助者和视频的支持及社会意义。研究发现,网友对视频众筹给予了充分的情感和工具支持,提供了信息和帮助,而平台算法为求助者提供了技术支持,让视频得以更广泛传播。然而,这种传播也引发了网友对平台和求助内容的质疑,围绕可信度展开了激烈争辩。视频众筹形式依赖平台算法和可见性设计,而非求助者的社交网络。尽管基于利他动机的社会支持有积极价值,但也造成了社会信任问题。

A Trusted and Privacy-Preserving Carpooling Matching Scheme in Vehicular Networks

With the rapid development of intelligent transportation, carpooling with the help of Vehicular Networks plays an important role in improving transportation efficiency and solving environmental problems. However, attackers usually launch attacks and cause privacy leakage of carpooling users. In addition, the trust issue between unfamiliar vehicles and passengers reduces the efficiency of carpooling. To address these issues, this paper introduced a trusted and privacy-preserving carpooling matching scheme in Vehicular Networks (TPCM). TPCM scheme introduced travel preferences during carpooling matching, according to the passengers’ individual travel preferences needs, which adopted the privacy set intersection technology based on the Bloom filter to match the passengers with the vehicles to achieve the purpose of protecting privacy and meeting the individual needs of passengers simultaneously. TPCM scheme adopted a multi-faceted trust management model, which calculated the trust value of different travel preferences of vehicle based on passengers’ carpooling feedback to evaluate the vehicle’s trustworthiness from multi-faceted when carpooling matching. Moreover, a series of experiments were conducted to verify the effectiveness and robustness of the proposed scheme. The results show that the proposed scheme has high accuracy, lower computational and communication costs when compared with the existing carpooling schemes.

In-situ preparation of TiO_(2)/N-doped graphene hollow sphere photocatalyst with enhanced photocatalytic CO_(2) reduction performance

Photocatalytic CO_(2)conversion efficiency is hampered by the rapid recombination of photogenerated charge carriers.It is effective to suppress the recombination by constructing cocatalysts on photocatalysts with high-quality interfacial contact.Herein,we develop a novel strategy to in-situ grow ultrathin/V-doped graphene(NG)layer on TiO_(2) hollow spheres(HS) with large area and intimate interfacial contact via a chemical vapor deposition(CVD).The optimized TiO^(2)/NG HS nanocomposite achieves total CO_(2)conversion rates(the sum yield of CO,CH_(3)OH and CH_(4))of 18.11μmol·g^(-1)h^(-1),which is about 4.6 times higher than blank T1O_(2)HS.Experimental results demonstrate that intimate interfacial contact and abundant pyridinic N sites can effectively facilitate photogenerated charge carrier separation and transport,realizing enhanced photocatalytic CO_(2)reduction performance.In addition,this work provides an effective strategy for in-situ construction of graphene-based photocatalysts for highly efficient photocatalytic CO_(2)conversion.

Secure Transmissions in Wireless Multiuser Networks Using Message Correlation

Due to the openness of wireless multiuser networks,the private information transmitted in uplink or downlink is vulnerable to eavesdropping.Especially,when the downlink transmissions use nonorthogonal multiple access(NOMA)techniques,the system further encounters interior eavesdropping.In order to address these security problems,we study the secret communication in multiuser networks with both uplink and downlink transmissions.Specifically,in uplink transmissions,the private messages transmitted in each slot are correlated,so any loss of the private information at the eavesdropper will prevent the eavesdropper from decoding the private information in later time slots.In downlink transmissions,the messages are correlated to the uplink information.In this way,any unexpected users who lose the expected user’s uplink information cannot decode its downlink information.The intercept probability is used to measure security performance and we analyze it in theory.Finally,simulation results are provided to corroborate our theoretical analysis.

Evaluation of Natural Radioactivity in Marine Sand Deposits from Offshore China

Natural radioactivity is very important for the assessment of the marine sand property and usability. By using gamma spectrometry, the concentration of the natural radionuclides 226Ra, 232Th and 40K have been measured in marine sand deposits from Liaodong Bay (LDB), North Yellow Sea (NYS), Zhoushan area (ZS), Taiwan Shoal (TS) and Pearl River Mouth (PR), offshore China, which are potential marine sand mining areas. The radiation activity equivalent (Raeq), indoor gamma absorbed dose rate (DR), annual effective dose (HR), alpha index (Ia), gamma index (Ig), external radiation hazard index (Hex), internal radiation hazard index (Hin), representative level index (RLI), excess lifetime cancer risk (ELCR) and annual gonadal dose equivalent (AGDE) associated with the natural radionuclides are calculated to assess the radiation hazard of the natural radioactivity in the marine sands offshore China. From the analysis, it is found that these marine sands are safe for the constructions. The Pearson correlation coefficient reveals that the 226Ra distribution in the marine sands offshore China is controlled by the variation of the 40K concentration. Principal component analysis (PCA) yields a two-component representation of the entire data from the marine sands, wherein 98.22% of the total variance is explained. Our results provide good baseline data to expand the database of radioactivity of building materials in China and all over the world.

Concentration-induced structural diversity and catalytic activity of BF3/n-BuOH complexes for n-decene polymerization

The BF3/n-BuOH complexes were investigated as active species in catalyzing n-decene polymerization reaction.The structures of BF3/n-BuOH complexes were characterized not only by modern spectrum but also by calculation at theoretical level. The results confirmed that BF3/n-BuOH complexes changed from BF3·(n-BuOH)2 complexes to BF3·n-BuOH complexes with the mass fraction of BF3 increasing. These two complexes have different catalytic activity, but BF3·n-BuOH was superior. The highest n-decene conversion could reach 99% and the most excellent selectivity of n-decene trimer and tetramer could reach up to 80% yield by a series of controlled conditions. This work can help to understand the catalytic active species of n-decene polymerization and provide support for industrialization of poly-alpha-olefins(PAOs).

Pore-water geochemistry in methane-seep sediments of the Makran accretionary wedge off Pakistan:Possible link to subsurface methane hydrate

Cold seeps are pervasive along the continental margin worldwide,and are recognized as hotspots for elemental cycling pathway on Earth.In this study,analyses of pore water geochemical compositions of one-400 cm piston core(S3)and the application of a mass balance model are conducted to assess methane-associated biogeochemical reactions and uncover the relationship of methane in shallow sediment with gas hydrate reservoir at the Makran accretionary wedge off Pakistan.The results revealed that approximately 77%of sulfate is consumed by the predominant biogeochemical process of anaerobic oxidation of methane.However,the estimated sulfate-methane interface depth is-400 cm below sea floor with the methane diffusive flux of 0.039 mol/(m^(2)·a),suggesting the activity of methane seepage.Based on the δ^(13)C_(DIC) mass balance model combined with the contribution proportion of different dissolved inorganic carbon sources,this study calculated the δ^(13)C of the exogenous methane to be-57.9‰,indicating that the exogenous methane may be a mixture source,including thermogenic and biogenic methane.The study of pore water geochemistry at Makran accretionary wedge off Pakistan may have considerable implications for understanding the specific details on the dynamics of methane in cold seeps and provide important evidence for the potential occurrence of subsurface gas hydrate in this area.

Resident to exhausted CD4^(+)T cell ratio is associated with the prognosis of gastric cancer

Gastric cancer(GC)ranks fifth for cancer incidence and fourth for mortality globally.1 Clinical outcomes have varied among patients receiving similar treatments at the same stage,suggesting the current prognostic tools remain somewhat flawed.2,3 single-cell analysis of GC data allowed us to dissect transcriptional programs underlying lymphocyte residency and exhaustion.

Immunosenescence:molecular mechanisms and diseases

Infection susceptibility,poor vaccination efficacy,age-related disease onset,and neoplasms are linked to innate and adaptive immune dysfunction that accompanies aging(known as immunosenescence).During aging,organisms tend to develop a characteristic inflammatory state that expresses high levels of pro-inflammatory markers,termed inflammaging.This chronic inflammation is a typical phenomenon linked to immunosenescence and it is considered the major risk factor for age-related diseases.Thymic involution,naïve/memory cell ratio imbalance,dysregulated metabolism,and epigenetic alterations are striking features of immunosenescence.Disturbed T-cell pools and chronic antigen stimulation mediate premature senescence of immune cells,and senescent immune cells develop a proinflammatory senescence-associated secretory phenotype that exacerbates inflammaging.Although the underlying molecular mechanisms remain to be addressed,it is well documented that senescent T cells and inflammaging might be major driving forces in immunosenescence.Potential counteractive measures will be discussed,including intervention of cellular senescence and metabolic-epigenetic axes to mitigate immunosenescence.In recent years,immunosenescence has attracted increasing attention for its role in tumor development.As a result of the limited participation of elderly patients,the impact of immunosenescence on cancer immunotherapy is unclear.Despite some surprising results from clinical trials and drugs,it is necessary to investigate the role of immunosenescence in cancer and other age-related diseases.

Synthesis of Mo_(2)C MXene with high electrochemical performance by alkali hydrothermal etching

Two-dimensional MXenes are generally prepared by the etching of acid solutions.The as-synthesized MXenes are terminated by acid group anions(F^(–),Cl^(–),etc.),which affect the electrochemical performance of MXenes.Here,we report a novel method to prepare Mo_(2)C MXene from Mo_(2)Ga_(2)C by the hydrothermal etching of alkali solutions.Highly pure Mo_(2)C MXene was successfully synthesized by the etching of NaOH,while the etchings of LiOH and KOH were failed.The concentration of NaOH,temperature,and time strongly affect the purity of as-prepared MXene.Pure Mo_(2)C MXene could be synthesized by the etching of 20 M NaOH at 180 for 24 h.After℃intercalation by hexadecyl trimethyl ammonium bromide at 90 for 96 h,few℃-layer Mo_(2)C MXene was obtained.The Mo_(2)C MXene made by NaOH etching after intercalation exhibited excellent performance as anode of lithium-ion battery,compared with general Mo_(2)C MXene made by HF etching and the Mo_(2)C MXene reported in literature.The final discharge specific capacity was 266.73 mAh·g^(−1)at 0.8 A·g^(−1),which is 52%higher than that Mo_(2)C made by HF etching(175.77 mAh·g^(−1)).This is because Mo_(2)C MXene made by NaOH etching has lager specific surface area,lower resistance,and pure O/OH termination without acid anion termination.This is the first report to make Mo_(2)C MXene by alkali etching and the samples made by this method exhibited significantly better electrochemical performance than the samples made by general HF etching.

Viral load kinetics of the severe acute respiratory syndrome coronavirus 2 Omicron variant in children aged 0 to 3 years and their parents

The Omicron variant of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)was first confirmed in November 2021 in South Africa^([1])and is more transmissible than other sub-variants.^([2])The influence of Omicron in children has been recognized with increased hospital admission rate than Delta wave.^([3,4])But severe clinical outcomes and comorbidity of Omicron are less than Delta in children.^([5])Hospitalized children during the Omicron period were more likely to be younger than that in the pre-Omicron period.^([6])

影响Omicron变异株感染轻型和普通型COVID-19患儿核酸转阴时间缩短因素分析

目的探讨Omicron变异株感染轻型与普通型新型冠状病毒疾病(COVID-19)患儿的临床特征及影响其核酸检测结果转为阴性(以下简称为"核酸转阴")时间缩短因素。方法选取2022年4月7日至5月20日上海交通大学医学院附属仁济医院南院区"亲子病房"集中收治的150例Omicron变异株感染轻型和普通型COVID-19患儿为研究对象。采用回顾性分析方法,根据这150例患儿的核酸转阴中位时间为13 d,将其分别纳入快转阴组(n=84,核酸转阴时间<13 d)和慢转阴组(n=66,核酸转阴时间≥13 d)。对2组患儿年龄、性别、轻型与普通型COVID-19患儿构成比、疫苗接种率、COVID-19相关临床表现及COVID-19发病48 h内系统炎症指数(SII)、中性粒细胞与淋巴细胞比值(NLR)、淋巴细胞与单核细胞比值(LMR)、血小板与淋巴细胞比值(PLR)等,进行成组t检验、Mann-Whitney U检验或χ2检验。采用多因素非条件logistic回归分析方法,分析影响Omicron变异株感染轻型与普通型COVID-19患儿核酸转阴时间缩短的因素。2组患儿合并基础疾病占比、采取对症治疗率等一般临床资料分别比较,差异均无统计学意义(P>0.05)。本研究遵循的程序符合2013修订的《世界医学协会赫尔辛基宣言》要求。结果①快转阴组患儿年龄、女性患儿比例、普通型COVID-19患儿比例、疫苗接种率,发热、咽痛、胃肠道症状发生率,均显著高于慢转阴组,而热峰、肌肉酸痛发生率,则均显著低于慢转阴组,2组比较,差异均有统计学意义(P<0.05)。②多因素非条件logistic回归分析结果显示,伴有咽痛、接种疫苗是轻型与普通型COVID-19患儿核酸转阴时间缩短的独立保护因素(OR=14.609、7.866,95%CI:1.108~192.697、1.313~47.121,P=0.042、0.024),而伴有肌肉酸痛、男性患儿则是其独立危险因素(OR=0.275、0.206,95%CI:0.087~0.874、0.083~0.511,P=0.029、0.001)。③快转阴组患儿SII为250.9×109/L(111.1×109/L,466.9×109/L),NLR为1.0(0.6,2.2),均分别显著高于慢转阴组的109.8×109/L(47.2×109/L,266.7×109/L)与0.5(0.2,1.2),并且差异均有统计学意义(Z=6.48、5.34,P=0.011、0.021)。快转阴组患儿LMR为4.1(2.5,9.4),显著低于慢转阴组的8.2(3.4,11.1),并且差异有统计学意义(Z=4.50,P=0.034)。结论轻型与普通型COVID-19患儿临床表现不典型,以发热、咳嗽为主,高SII、NLR及低LMR患儿核酸转阴时间较短,接种疫苗、伴有咽痛是促进核酸转阴时间缩短的保护性因素,伴有肌肉酸痛及男性是影响核酸转阴时间缩短的危险因素。

Solar fuel generation over nature-inspired recyclable TiO_(2)/g-C_(3)N_(4)S-scheme hierarchical thin-film photocatalyst

Preparation of efficient photocatalysts with ease of recovery in solar fuel generation is highly desired to achieve carbon neutralization in carbon dioxide(CO_(2))emissions.Inspired from the forest with superior light penetration and fast gas transport,a TiO_(2)/g-C_(3)N_(4)composite nanowire arrays(NAs)film with maximized light utilization is devised.It is achieved by in-situ coating a thin layer of g-C_(3)N_(4)(as the leaf)on the vertically-oriented TiO_(2)arrays(as tree trunks)on Ti foil(as soil).Benefiting from the effective charge separation by S-scheme charge transfer,intimate contact by the in-situ growth as well as the ingenious structure,the composite,readily recyclable,displays exciting performance in photocatalytic CO_(2)reduction.It is beyond doubt that the combination of heterojunction construction and“nature-inspired biomimetic photocatalyst”design promises practical applications and industrial use.

Two-dimensional vanadium carbide(V2CTx) MXene as supercapacitor electrode in seawater electrolyte

In this study,two-dimensional V2CTx MXene has been prepared by selectively etching Al layers from V2 AlC MAX phase by NaF+HCl etching at 90℃for 72 h and its performance as supercapacitor(SC)electrode were tested using simulating seawater as electrolyte.V2CTx MXene-based electrodes shows a good capacitance of 181.1 F/g,which is in accordance with the volumetric specific capacitance of 317.8 F/cm^3,and with 89.1%capacitance retention even after 5000 cycle.Compared with other MXenes,V2CTx have better electrochemical performance as SC electrode.This work provides an innovative strategy to apply V2CTx MXene as SC electrode in safety and effective seawater electrolyte.

Electrochemical performance of Ti_(3)C_(2)supercapacitors in KOH electrolyte

Two-dimensional(2D)carbide Ti_(3)C_(2)was synthesized by exfoliating Ti_(3)AlC_(2)in HF solution and used for supercapacitive performance investigation in 3 M KOH electrolyte.The specific surface area(SSA)of as-synthesized Ti_(3)C_(2)was 22.35 m^(2)/g.Ti_(3)C_(2)-based supercapacitor electrodes exhibited good energy storage ability and had a volumetric capacitance 119.8 F/cm^(3)at the current density of 2.5 A/g.Moreover,the addition of carbon black into Ti_(3)C_(2)powders greatly improved the performance of Ti_(3)C_(2)-based capacitors because carbon black restrained the preferred orientation of 2D Ti_(3)C_(2),providing fast ion transport channels,and in turn,decreasing electrical resistance from 16.7Ωto 3.5Ω.

Carbon dioxide adsorption of two-dimensional carbide MXenes

Two-dimensional carbide MXenes(Ti_3C_2T_x and V_2CT_x)were prepared by exfoliating MAX phases(Ti_3AlC_2 and V_2AlC)powders in the solution of sodium fluoride(NaF)and hydrochloric acid(HCl).The specific surface area(SSA)of as-prepared Ti_3C_2T_x was 21 m^2/g,and that of V_2CT_x was 9 m^2/g.After intercalation with dimethylsulfoxide,the SSA of Ti_3C_2T_x was increased to 66 m^2/g;that of V_2CT_x was increased to 19 m^2/g.Their adsorption properties on carbon dioxide(CO_2)were investigated under 0–4 MPa at room temperature(298 K).Intercalated Ti_3C_2T_x had the adsorption capacity of 5.79 mmol/g,which is close to the capacity of many common sorbents.The theoretical capacity of Ti_3C_2T_x with the SSA of 496 m^2/g was up to 44.2 mmol/g.Additionally,due to high pack density,MXenes had very high volume-uptake capacity.The capacity of intercalated Ti_3C_2T_(x )measured in this paper was 502 V·v^(–1).This value is already higher than volume capacity of most known sorbents.These results suggest that MXenes have some advantage features to be researched as novel CO_2 capture materials.

Synthesis and electrochemical properties of V_(2)C MXene by etching in opened/closed environments

The effect of etching environment(opened or closed)on the synthesis and electrochemical properties of V_(2)C MXene was studied.V_(2)C MXene samples were synthesized by selectively etching of V2AlC at 90℃in two different environments:opened environment(OE)in oil bath pans under atmosphere pressure and closed environment(CE)in hydrothermal reaction kettles under higher pressures.In OE,only NaF(sodium fluoride)+HCl(hydrochloric acid)etching solution can be used to synthesize highly pure V_(2)C MXene.However,in CE,both LiF(lithium fluoride)+HCl and NaF+HCl etchant can be used to prepare V_(2)C MXene.Moreover,the V_(2)C MXene samples made in CE had higher purity and better-layered structure than those made in OE.Although the purity of V_(2)C obtained by LiF+HCl is lower than that of V_(2)C obtained using NaF+HCl,it shows better electrochemical performance as anodes of lithium-ion batteries(LIBs).Therefore,etching in CE is a better method for preparing highly pure V_(2)C MXene,which provides a reference for expanding the synthesis methods of V_(2)C with better electrochemical properties.

Land cover classification from remote sensing images based on multi-scale fully convolutional network

Although the Convolutional Neural Network(CNN)has shown great potential for land cover classification,the frequently used single-scale convolution kernel limits the scope of informa-tion extraction.Therefore,we propose a Multi-Scale Fully Convolutional Network(MSFCN)with a multi-scale convolutional kernel as well as a Channel Attention Block(CAB)and a Global Pooling Module(GPM)in this paper to exploit discriminative representations from two-dimensional(2D)satellite images.Meanwhile,to explore the ability of the proposed MSFCN for spatio-temporal images,we expand our MSFCN to three-dimension using three-dimensional(3D)CNN,capable of harnessing each land cover category’s time series interac-tion from the reshaped spatio-temporal remote sensing images.To verify the effectiveness of the proposed MSFCN,we conduct experiments on two spatial datasets and two spatio-temporal datasets.The proposed MSFCN achieves 60.366%on the WHDLD dataset and 75.127%on the GID dataset in terms of mIoU index while the figures for two spatio-temporal datasets are 87.753%and 77.156%.Extensive comparative experiments and abla-tion studies demonstrate the effectiveness of the proposed MSFCN.

Construction and performance of CdS/MoO_(2)@Mo_(2)C-MXene photocatalyst for H_(2) production

Nowadays,photocatalytic technologies are regarded as promising strategies to solve energy problems,and various photocatalysts have been synthesized and explored.In this paper,a novel CdS/MoO_(2)@Mo_(2)C-MXene photocatalyst for H_(2)production was constructed by a two-step hydrothermal method,where MoO_(2)@Mo_(2)C-MXene acted as a binary co-catalyst.In the first hydrothermal step,MoO_(2)crystals with an egged shape grew on the surface of two-dimensional(2D)Mo_(2)C MXene via an oxidation process in HCl aqueous solution.In the second hydrothermal step,CdS nanorods were uniformly assembled on the surface of MoO_(2)@Mo_(2)C-MXene in ethylenediamine with an inorganic cadmium source and organic sulfur source.The CdS/MoO_(2)@Mo_(2)C-MXene composite with MoO_(2)@Mo_(2)C-MXene of 5 wt%exhibits an ultrahigh visible-light photocatalytic H_(2)production activity of 22,672μmol/(g·h),which is~21%higher than that of CdS/Mo_(2)C-MXene.In the CdS/MoO_(2)@Mo_(2)C-MXene composite,the MoO_(2)with metallic nature separates CdS and Mo_(2)C MXene,which acts as an electron-transport bridge between CdS and Mo_(2)C MXene to accelerate the photoinduced electron transferring.Moreover,the energy band structure of CdS was changed by MoO_(2)@Mo_(2)C-MXene to suppress the recombination of photogenerated carriers.This novel compound delivers upgraded photocatalytic H_(2)evolution performance and a new pathway of preparing the low-cost photocatalyst to solve energy problems in the future.

Corrosion behavior of Ti_(3)AlC_(2) in molten KOH at 700℃

This paper investigated the corrosion behaviors of Ti_(3)AlC_(2) at 700℃in molten KOH with various mass ratios.If the mass ratio of KOH:Ti_(3)AlC_(2)≤2,Ti_(3)AlC_(2) can resist KOH hot corrosion in 2 h.Ti_(3)AlC_(2) suffered serious corrosion attack if the mass ratio≥3.The main compositions of corroded samples were amorphous graphite and potassium titanates(K_(2)O·nTiO_(2)).If the samples were washed by acid and dried,potassium titanates could decompose to K_(2)O and amorphous rutile.Based on the experimental results,a corrosion mechanism of Ti_(3)AlC_(2) in molten KOH was proposed.