Preparation,properties,and applications of Bi_(2)O_(2)Se thin films:A review

Two-dimensional materials have shown great application potential in high-performance electronic devices because they are ultrathin,have an ultra-large specific surface area,high carrier mobility,efficient channel current regulation,and extraordinary integration.In addition to graphene,other types of 2D nanomaterials have also been studied and applied in photodetectors,solar cells,energy storage devices,and so on.Bi_(2)O_(2)Se is an emerging 2D semiconductor material with very high electron mobility,modest bandgap,near-ideal subthreshold swing,and excellent thermal and chemical stability.Even in a monolayer structure,Bi_(2)O_(2)Se has still exhibited efficient light absorption.In this mini review,the latest main research progresses on the preparation methods,electric structure,and the optical,mechanical,and thermoelectric properties of Bi_(2)O_(2)Se are summarized.The wide rang of applications in electronics and photoelectronic devices are then reviewed.This review concludes with a discussion of the existing open questions/challenges and future prospects for Bi_(2)O_(2)Se.

Factors associated with gastric adenocarcinoma and dysplasia in patients with chronic gastritis:a population-based study

Objective： Gastric cancer （GC） is one of the leading causes of death in China and other Asian countries. Recently, gastric endoscopy has become the main approach for GC screening, but the identification of high-risk individuals remains a challenge in GC screening programs. Methods： There were 7,302 patients with chronic gastritis involved in this study. Endoscopic examinations were performed, and their demographic characteristics and lifestyle data were collected. Each possible associated factor of GC/premalignant and precursor lesions was evaluated by univariate and multivariate logistic regressions. Nomograms were used for visualization of those models, and receiver operating characteristic （ROC） curve analysis was used to present the predictive accuracy. Resu Its： We detected 8 （0.11% ） gastric adenocarcinomas, 17 （0.23 %） dysplasia cases, 14 （0.19%） hyperplasia cases, 52 （0.71%） intestinal metaplasia cases, 217 （2.97%） inflammatory lesions, 141 （1.93%） gastric ulcers, 10 （0.14%） atrophic gastritis cases, 1,365 （18.69%） erosive gastritis cases, and 5,957 （81.58%） superficial gastritis cases in 7,302 patients. The age （P〈0.001）, gender （P=0.086）, labor intensity （P=0.018） and leek food intake （P=0.143） were identified as independent predictive factors of GC/premalignant lesions possibility. The corresponding nomogram exhibited an area under the curve （AUC） [95% confidence interval （95% CI）] of 0.82 （0.74-0.89） for the modeling group and 0.80 （0.75-0.85） for the validation group. The age （P=0.002）, gender （P=0.024）, smoldng （P=0.002） and leek food intake （P=0.039） were independent predictive factors of precursor lesions possibility. The corresponding nomogram exhibited an AUC （95% CI） of 0.62 （0.60-0.65） for the modeling group and 0.61 （0.59-0.63） for the validation group. Conclusions： We identified several potential associated factors and provided a preclinical nomogram with the potential to predict the possibility of GC/premalignant and precursor lesions.

时间效应在悬滴法测定表面张力中的影响

表面张力是流体重要的物理性质,测定表面张力的方法通常包括毛细管上升法、最大气泡压力法、拉环法、旋滴法和悬滴法等。目前,最普遍的表面张力的测定方法为国家标准推荐的平板法或拉环法。然而,悬滴法作为一项成熟的表面张力测定方法且具备静态表面张力及动态表面张力测定功能,目前使用该法测定的较少。文章使用悬滴法测定较低含量的表面活性剂溶液静态表面张力时发现结果与拉环法差异较大,而测定单组分液体及含量较大的表面活性剂溶液,悬滴法与拉环法的测定数据差异较小,这种情况的相关报道较少。另外,使用动态表面张力测定探索了静态测定时出现差异的原因,并对应用悬滴法进行表面张力测定的适用范围进行了总结。使用悬滴法测定表面张力时,应注意时间效应的影响。

HTRA1多态性与汉族人群湿性年龄相关性黄斑变性遗传易感性的关系

目的:探讨高温必需因子A-1(HTRA1)多态性与汉族人群湿性年龄相关性黄斑变性(AMD)遗传易感性的关系。方法:选取本院2014-05/2017-01收治的汉族湿性AMD患者201例,汉族正常健康者201例,分别设为病例组和健康组。采集研究对象外周静脉血样并提取基因组DNA,利用Sequenom质谱分析平台对HTRA1基因的rs11200638、rs2248799位点进行基因型检测,分析HTRA1多态性与湿性AMD遗传易感性的关系。结果:两组研究对象rs11200638、rs2248799位点的基因型等级分布比较,差异均有统计学意义(P<0.01),病例组AA、TT的频率分别为51.2%、57.7%,健康组AA、TT的频率分别为20.9%、28.4%,前者均明显高于后者,差异均有统计学意义(P<0.01);病例组rs11200638位点危险性等位基因A与rs2248799位点危险性等位基因T分布的频率分别为69.7%、73.6%,健康组分别为45.8%、52.5%,前者均明显高于后者,差异均有统计学意义(P<0.01)。rs11200638基因型AA、AG的OR值分别为5.36与3.45,是湿性AMD发病的危险因素(P<0.01);rs2248799基因型TT、TC的OR值分别为2.36与1.98,是湿性AMD发病的危险因素(P<0.01)。结论:HTRA1基因rs11200638和rs2248799多态性与湿性AMD发病关系显著,基因型AA、TT与汉族人群湿性AMD患病风险关系密切,其频率增高可增加湿性AMD患病风险。

Correlation between intrinsic dipole moment and pyroelectric coefficient of Fe-Mg tourmaline

Single-crystal X-ray diffraction structural data of four Fe-Mg tourmalines with different Fe contents from Xinjiang, Sichuan, and Yunnan Provinces, China, were collected at room temperature and-100oC. The intrinsic dipole moments of polyhedra and the total intrinsic dipole moment of the unit cell were calculated. By comparing the intrinsic electric dipole moments of the X, Y, Z, T, and B site polyhedra, it is found that the T site polyhedron makes the greatest contribution to the total intrinsic dipole moment. The pyroelectric coefficients of four Fe-Mg tourmalines were experimentally determined, and the influence of intrinsic dipole moments on their pyroelectric properties was inves-tigated. The experimental results show that, compared with the case at room temperature, the intrinsic dipole moments change with the total Fe content at-100oC in a completely different way. With the decrease of temperature, the total intrinsic dipole moments of tourmaline de-crease. Over the same temperature interval, the pyroelectric coefficients increase with the increase in intrinsic dipole moment.

First-principles calculation of influences of La-doping on electronic structures of KNN lead-free ceramics

The electronic structures of lead-free piezoceramic(K0.5Na0.5)NbO3(KNN)and La-doped KNN((K0.5Na0.5)0.994La0.006NbO3)are studied by using first principles calculation on the basis of density functional theory(DFT).The results reveale that the piezoelectricity stems from strong hybridization between the Nb atom and the O atom.At the same time,the K or Na atoms are replaced by the La doping atoms,which brings about the anisotropic relaxation.The La doping reduces the forbidden band,at the same time it makes Fermi surfaces shift toward the energetic conduction band(CB)of KNN.With the increase of La-doping intent,the phase structure of KNN extends from O-phase to T-phase and improves the piezoelectric properties of KNN.

用于常见疾病成像的纳米材料造影剂

生物医学精准诊断对于疾病的有效治疗十分重要.纳米基成像造影剂具有灵敏度高、特异性强、生物相容性好等特点,在生物医学成像诊断中具有巨大的临床转化潜力.目前,尽管研究者们构筑了大量的纳米基探针材料作为疾病诊断造影剂,但纳米材料造影剂在临床转化方面仍然面临极大的挑战.这里我们主要概述了不同生物医学成像类型的纳米基造影剂所面临的问题,并针对这些难题提出了应对方案和未来的研究重点,最后对纳米基造影剂的临床转化前景进行了展望.

Significantly enhanced performance and conductivity mechanism in Nb/Mn co-doped CaBi_(4)Ti_(4)O_(15)ferroelectrics

With the rapid development of high-end industries,the demand for high-temperature piezoelectric materials is significantly increasing.However,realizing the ultra-high performance to meet more ap-plications still faces major scientific and engineering challenges of our time.Here,a new Nb/Mn co-doped CaBi_(4)Ti_(4)O_(15)(CBT)high-temperature piezoelectric material system of CaBi_(4)Ti_(4-x)(Nb_(2/3)Mn_(1/3))_(x)O_(15)was synthesized by the conventional solid-state sintering method.The results show that the addition of the dopants tends to break the long-range ferroelectric chain and soften the flexibility of polarization,resulting in more distorted crystal structure and better ferroelectric properties of CBT ceramics.The ultra-high piezoelectric constant(d_(33)=26.8 pC/N)is thus attained in CBT-based ceramics with x=0.12,which is about several times larger than that of pure CBT ceramics.Moreover,numerous nano-sized layered domain structures that lie on the lateral plane of grains are observed in ceramics,with lower domain wall energy and better dynamic features under electric fields,mainly responsible for the origin of enhanced performance.Besides,excess dopants could make the conductivity mechanism of CBT ceramics transform from p-type to n-type,and also result in a shift of conduction relaxation mechanism from defect dipole rotation polarization to electron relaxation polarization.The work not only provides a promising candidate for high-temperature piezoelectric materials,but also opens a window for opti-mizing performance by tailoring domain structures using chemical modification.

Enhanced electrical properties and Vickers hardness of calcium bismuth niobate ceramics by W/Co substituted at B-site

Calcium bismuth niobate(CBN)ceramic,as a core element of high-temperature piezoelectric sensors,has attracted widespread attention due to its high Curie temperature within the class of Aurivillius compounds.However,CBN usually faces two shortcomings.poor piezoelectric constant and low resistivity.In this work,CBN-based ceramics with donor–acceptor ions(W/Co)co-substituted at B-site were prepared by solid-state reaction method,and structure–property relationship of ceramics was studied in detail.Co-substitution of W/Co ions effectively improved the electrical property and hardness of CBN ceramics.CaBi_(2)Nb_(1.91)(W_(2/3)Co_(1/3)T_(0.09)O_(9))exhibits enhanced electrical and mechanical properties including high resistivity of-10^(7)Ω·cm at 500℃,piezoelectric constant of-15.3 pC/N and hardness value of-3.57 GPa.These values are two orders of magnitude,over two times,and 1.36 times higher than those of pure CBN ceramic,respectively.This work provides a reference for exploring other bismuth-layered structural ceramics.

Modifiable risk factors for esophageal cancer in endoscopic screening population:A modeling study

To the Editor:Esophageal cancer,one of the most common cancer types in China,with an estimated 346,633 new cases and 323,600 deaths in 2022,is becoming an increasingly serious clinical and public health problem.^([1])The successful promotion of the self-management strategy has indicated that lifestyle modifications can be valuable in the primary prevention of cancer development.Adopting a healthy lifestyle has become a novel strategy for primary prevention and risk reduction in high-risk areas.Previous epidemiological studies have identified several lifestyle-related risk factors for esophageal cancer,including smoking and diet.^([2])Each factor can typically explain a modest proportion of cancer risk.However,when combined,these known risk factors may substantially affect the risk of esophageal cancer.Nevertheless,some risk factors for esophageal cancer are non-modifiable,including age,low socioeconomic status,and family history.Whether and how these non-modifiable risk factors affect primary cancer prevention by intervening with modifiable risk factors remain unclear.

内镜逆行胰胆管造影术困难胆管插管方式的研究进展

成功选择性胆管插管是进行内镜逆行胰胆管造影术的关键,如何有效提高困难胆管插管成功率并降低术后胰腺炎发生率是目前医学讨论热点。本文总结不同内镜逆行胰胆管造影术插管方式,为困难胆管插管方式选择提供参考。

Boosting Whale Optimizer with Quasi-Oppositional Learning and Gaussian Barebone for Feature Selection and COVID-19 Image Segmentation

Whale optimization algorithm(WOA)tends to fall into the local optimum and fails to converge quickly in solving complex problems.To address the shortcomings,an improved WOA(QGBWOA)is proposed in this work.First,quasi-opposition-based learning is introduced to enhance the ability of WOA to search for optimal solutions.Second,a Gaussian barebone mechanism is embedded to promote diversity and expand the scope of the solution space in WOA.To verify the advantages of QGBWOA,comparison experiments between QGBWOA and its comparison peers were carried out on CEC 2014 with dimensions 10,30,50,and 100 and on CEC 2020 test with dimension 30.Furthermore,the performance results were tested using Wilcoxon signed-rank(WS),Friedman test,and post hoc statistical tests for statistical analysis.Convergence accuracy and speed are remarkably improved,as shown by experimental results.Finally,feature selection and multi-threshold image segmentation applications are demonstrated to validate the ability of QGBWOA to solve complex real-world problems.QGBWOA proves its superiority over compared algorithms in feature selection and multi-threshold image segmentation by performing several evaluation metrics.

GSH responsive traditional clinical drugs probe for cancer cell fluorescence imaging and therapy

Despite the rapid development of fluorescence detection modalities for disease diagnosis,novel fluorescent molecules and probes still face with tremendous pressure to transform before employing such fluorescent tools in the clinic.Impressively,the fluorescent probes based on the traditional fluorescent dye are expected to accelerate the transformation process.Herein,methylene blue is requisitioned to design the GSH responsive probe MB-SS-CPT elaborately.The as-synthesized MB-SS-CPT provides a dramatic optical advantage for GSH detection in vitro,cell fluorescence imaging,in vivo imaging,and antitumor therapy.

Strategies of strengthening mechanical properties in the osteoinductive calcium phosphate bioceramics

Calcium phosphate(CaP)bioceramics are widely applied in the bone repairing field attributing to their excellent biological properties,especially osteoinductivity.However,their applications in load-bearing or segmental bone defects are severely restricted by the poor mechanical properties.It is generally considered that it is challenging to improve mechanical and biological properties of CaP bioceramics simultaneously.Up to now,various strategies have been developed to enhance mechanical strengths of CaP ceramics,the achievements in recent researches need to be urgently summarized.In this review,the effective and current means of enhancing mechanical properties of CaP ceramics were comprehensively summarized from the perspectives of fine-grain strengthening,second phase strengthening,and sintering process optimization.What’s more,the further improvement of mechanical properties for CaP ceramics was prospectively proposed including heat treatment and biomimetic.Therefore,this review put forward the direction about how to compatibly improve mechanical properties of CaP ceramics,which can provide data and ideas for expanding the range of their clinical applications.

产品吸引力、全要素生产率与企业出口市场份额

本文通过建立理论模型分析了产品吸引力和生产率两个维度的企业异质性对企业出口市场份额的影响和相对重要性。利用2000~2006年中国海关数据库与中国工业企业数据库以及联合国商品贸易统计数据库的匹配数据,通过估计得到企业层面代表产品吸引力的需求指数和全要素生产率,通过计算得到企业在出口目的地的市场份额,对我国12个具有代表性的制造业行业进行验证。实证结果与理论预测相一致,产品吸引力和生产率都在解释企业出口市场份额时发挥了重要作用。通过检验产品吸引力和生产率与企业在出口目的地的市场份额之间的关系得出:替代品越少、增加产品吸引力的边际成本越小,增加产品吸引力越有利于扩大企业出口市场份额;替代品越多、增加产品吸引力的边际成本越大,提高生产率以降低成本来扩大企业出口市场份额的效果越明显。

Oxygen octahedron tilting,electrical properties and mechanical behaviors in alkali niobate-based lead-free piezoelectric ceramics

In this work,we present a new piezoelectric solid solution consisting of two typical alkali niobate-based materials,K_(0.5)Na_(0.5)NbO_(3)(KNN)and Li_(0.15)Na_(0.85)NbO_(3)(LNN).Although KNN and LNN have the same perovskite structure,they exhibit extremely different electrical properties and mechanical behaviors.The phase structures,electrical and mechanical evolutions of the new lead-free piezoelectric materials with different ratios of KNN and LNN are comprehensively and theoretically investigated.According to the Xray diffraction patterns and curves of permittivity versus temperature,a series of complicated phase transitions can be found with varied LNN content.Rietveld refinement results based on XRD patterns reveal an oxygen octahedron tilting in the LNN-rich crystal structure,and simultaneously the reasons for octahedron tilting are discussed.The distorted crystal structure is accompanied by extremely decreased electric properties but increased mechanical properties,which reveals electrical and mechanical properties of alkali niobate-based piezoelectric ceramics strongly depend on their inner structures,and the enhancement of intrinsic hardness results in the deterioration of piezoelectric properties.Our work exhibits the detailed evolutions of structure,electrical and mechanical properties from KNN to LNN,which provides experimental and theoretical basis for development of new alkali niobate-based piezoelectric materials.

Efficacy and Safety of Domestic Leuprorelin in Girls with Idiopathic Central Precocious Puberty： A Multicenter,Randomized, Parallel, Controlled Trial

Background：In central precocious puberty （CPP）,the pulse secretion and release ofgonadotropin-releasing hormone （GnRH） are increased due to early activation of the hypothalamic-pituitary-gonadal axis,resulting in developmental abnormalities with gonadal development and appearance of secondary sexual characteristics.The CPP without organic disease is known as idiopathic CPP （ICPP）.The objective of the study was to evaluate the clinical efficacy and safety of domestic leuprorelin （GnRH analog） in girls with ICPP.Methods：A total of 236 girls with ICPP diagnosed from April 2012 to January 2014 were selected and were randomized into two groups.One hundred fifty-seven girls in the test group were treated with domestic leuprorelin acetate,79 girls in the control group were treated with imported leuprorelin acetate.They all were treated and observed for 6 months.After 6-month treatment,the percentage of children with peak luteinizing hormone （LH） ≤3.3 U/L,the percentage of children with peak LH/peak follicle stimulating hormone （FSH） ratio 〈0.6,the improvements of secondary sexual characteristics,gonadal development and sex hormone levels,the change of growth rate of bone age （BA） and growth velocity,and drug adverse effects between two groups were compared.Results：After the treatment,the percentage of children with a suppressed LH response to GnRH,defined as a peak LH ≤3.3 U/L,at 6 months in test and control groups were 96.80% and 96.20%,respectively,and the percentage of children with peak LH/FSH ratio ≤0.6 at 6 months in test and control groups were 93.60% and 93.70%,respectively.The sizes of breast,uterus and ovary of children and the levels of estradiol （E2） were significantly reduced,and the growth rate of BA was also reduced.All the differences between pre-and post-treatment in each group were statistically significant （P 〈 0.05）,but the differences of the parameters between two groups were not significant （P 〉 0.05）.Conclusions：Domestic leuprorelin is effective and safe in the treatment of Chinese girls with ICPP.Its effectiveness and safety are comparable with imported leuprorelin.

Potassium sodium niobate based lead-free ceramic for high-frequency ultrasound transducer applications

The BiAlO_(3)(BA)and(Bi_(0.5)Na_(0.5))ZrO_(3)(BNZ)are selected to form a solid solution with(K_(0.48)Na_(0.52))NbO_(3) via traditional solid state technique to optimize the electrical performance and temperature stability of KNNbased lead-free ceramics,simultaneously.Here we show that doped BA has a great influence on phase structure,morphologies,and electrical properties.The XRD patterns and dielectric constant versus temperature curves reveal that an increase in the BA content results in a transform of phase structures from a coexistence state of rhombohedral,orthorhombic and tetragonal phases to pseudocubic phase.Owing to the construction of R-O-T phase boundary,optimized performances(T_(C)~336℃,d_(33)~306 pC/N,kp=0.48)are obtained in 0.962(K_(0.48)Na_(0.52))NbO_(3)-0.003BiAlO_(3)-0.035(Bi_(0.5)Na_(0.5))ZrO_(3)(KNN-3)ceramics.Based on the sintered KNN-3 ceramic samples,high-frequency ultrasound imaging transducers are designed and fabricated,which exhibits a high center frequency of 24.5 MHz,a broad -6 dB bandwidth of 97% and a high-sensitivity.Finally,the imaging characteristic of the lead-free transducers is demonstrated via ex vivo imaging of biological tissue structure.As environment friendly materials,the excellent electrical and acoustic performance of developed KNN-based ceramics has great potential for practical applications.

PbS quantum dots as a saturable absorber for ultrafast laser

Low-dimensional nanomaterials, owing to their unique and versatile properties, are very attractive for enormous electronic and optoelectronic applications. PbS quantum dots(QDs), characterized by a large Bohr radius and size-tunable bandgap, are especially interesting for photonic applications in the near-infrared region. Here, oleic acid capped colloidal PbS QDs as a saturable absorber are investigated for ultrashort-pulse generation. The PbS QDs exhibit outstanding nonlinear saturable absorption properties at 1550 nm: a modulation depth up to 44.5%and a thermal damage threshold larger than 30 mJ∕cm^2. By incorporating PbS QDs into a fiber laser, a transform-limited soliton pulse as short as 559 fs with a bandwidth of 4.78 nm is realized at 1563 nm. Numerous applications may benefit from the nonlinear saturable absorption properties of PbS QDs, such as near-infrared pulsed lasers and

Quality evaluation of Farfarae Flos by ITS/ITS2 and HPLC fingerprint analysis

The flower bud of Tussilago farfara L.,also known as Farfarae Flos(FF),is commonly used in the traditional Chinese medicine(TCM)for the treatment of cough,bronchitis and asthmatic disorders.In this study,26 samples from five provinces across northern China were collected,and internal transcribed spacer-polymerase chain reaction(ITS-PCR)coupled with high performance liquid chromatography(HPLC)fingerprint profiling was used for the quality evaluation of FF.The results of the ITS sequence analysis showed the high similarity values among these samples.ITS2 sequence exhibited less molecular diversity compared with ITS1,and no obvious correlation was found between the variation of ITS with the production areas or cultivation methods.The results of HPLC fingerprints in combination with the similarity analysis suggested that relative contents of phenylpropanoids and flavonoids varied among the 26 FF samples,and there was also no obvious difference among the different habitats.The phenylpropanoids and the flavonoids showed similar fluctuating patterns,and positive correlation among them was also observed.The results presented in this study suggested that FF from different habits showed high similarities,and ITS-PCR coupled with HPLC fingerprint profiling could be used as a valuable approach for the quality evaluation of FF.