Spark Plasma Sintering of Boron Carbide Using Ti_(3)SiC_(2) as a Sintering Additive

Boron carbide has unique properties for wide application possibilities;however,poor sinterability limits its applications.One approach to overcome this limitation is the addition of secondary phases into boron carbide.Boron carbide based composite ceramics are produced by the direct addition of secondary phases into the structure or via reactive sintering using a sintering additive.The present study investigated the effect of Ti_(3)SiC_(2) addition to boron carbide by reactive spark plasma sintering in the range of 1700-1900℃.Ti_(3)SiC_(2) phase decomposed at high temperatures and reacted with B4C to form secondary phases of TiB2 and SiC.The results demonstrated that the increase of Ti_(3)SiC_(2) addition(up to 15 vol%)effectively promoted the densification of B4C and yielded higher hardness.However,as the amount of Ti_(3)SiC_(2) increased further,the formation of microstructural inhomogeneity and agglomeration of secondary phases caused a decrease in hardness.

Investor sentiments and stock marketsduring the COVID-19 pandemic

This study examines the relationship between positive and negative investor sentiments and stock market returns and volatility in Group of 20 countries using variousmethods, including panel regression with fixed effects, panel quantile regressions, apanel vector autoregression (PVAR) model, and country-specific regressions. We proxyfor negative and positive investor sentiments using the Google Search Volume Indexfor terms related to the coronavirus disease (COVID-19) and COVID-19 vaccine, respectively. Using weekly data from March 2020 to May 2021, we document significantrelationships between positive and negative investor sentiments and stock marketreturns and volatility. Specifically, an increase in positive investor sentiment leads toan increase in stock returns while negative investor sentiment decreases stock returnsat lower quantiles. The effect of investor sentiment on volatility is consistent acrossthe distribution: negative sentiment increases volatility, whereas positive sentimentreduces volatility. These results are robust as they are corroborated by Granger causalitytests and a PVAR model. The findings may have portfolio implications as they indicatethat proxies for positive and negative investor sentiments seem to be good predictorsof stock returns and volatility during the pandemic.

A New Hybrid Approach Using GWO and MFO Algorithms to Detect Network Attack

This paper addresses the urgent need to detect network security attacks,which have increased significantly in recent years,with high accuracy and avoid the adverse effects of these attacks.The intrusion detection system should respond seamlessly to attack patterns and approaches.The use of metaheuristic algorithms in attack detection can produce near-optimal solutions with low computational costs.To achieve better performance of these algorithms and further improve the results,hybridization of algorithms can be used,which leads to more successful results.Nowadays,many studies are conducted on this topic.In this study,a new hybrid approach using Gray Wolf Optimizer(GWO)and Moth-Flame Optimization(MFO)algorithms was developed and applied to widely used data sets such as NSL-KDD,UNSW-NB15,and CIC IDS 2017,as well as various benchmark functions.The ease of hybridization of the GWO algorithm,its simplicity,its ability to perform global optimal search,and the success of the MFO algorithm in obtaining the best solution suggested that an effective solution would be obtained by combining these two algorithms.For these reasons,the developed hybrid algorithm aims to achieve better results by using the good aspects of both the GWO algorithm and the MFO algorithm.In reviewing the results,it was found that a high level of success was achieved in the benchmark functions.It achieved better results in 12 of the 13 benchmark functions compared.In addition,the success rates obtained according to the evaluation criteria in the different data sets are also remarkable.Comparing the 97.4%,98.3%,and 99.2% classification accuracy results obtained in the NSL-KDD,UNSW-NB15,and CIC IDS 2017 data sets with the studies in the literature,they seem to be quite successful.

Effect of Stacking Fault Energy on the Mechanism of Texture Formation during Alternating Bending of FCC Metals and Alloys

Alternating bending shear stresses lead to the formation of twin orientations in the texture of FCC materials with middle and low stacking fault energy (SFE). Only in the stainless steel with a low SFE during alternating bending with different number of cycles components of shear texture {111};{hkl};{001} were formed. Copper (middle SFE), along with orientations of twinning and cubic texture formed orientation of deformation {135}. During alternating bending of aluminum (high SFE), a dynamic recovery occurred. The share of initial cubic texture increases with the increase of number of cycles of alternating bending and reaches its maximum after three cycles. Share of component of texture Goss increased slightly. The most significant change of the microstructure and texture occurred during the first 3 - 5

Hypertrophic cardiomyopathy: Can the noninvasive diagnostic testing identify high risk patients?

Hypertrophic cardiomyopathy(HCM) is the most common cause of sudden cardiac death(SCD) in the young, particularly among athletes. Identifying high risk individuals is very important for SCD prevention. The purpose of this review is to stress that noninvasive diagnostic testing is important for risk assessment. Extreme left ventricular hypertrophy and documented ventricular tachycardia and fibrillation increase the risk of SCD. Fragmented QRS and T wave inversion in multiple leads are more common in high risk patients. Cardiac magnetic resonance imaging provides complete visualization of the left ventricular chamber, allowing precise localization of the distribution of hypertrophy and measurement of wall thickness and cardiac mass. Moreover, with late gadolinium enhancement, patchy myocardial fibrosis within the area of hypertrophy can be detected, which is also helpful in risk stratification. Genetic testing is encouraged in all cases, especially in those with a family history of HCM and SCD.

Dynamic Responses of Block Type Quay Walls Under Cyclic Loading

The purpose of this research is to study the dynamic responses of gravity quay walls with block type consisting of“three blocks”experimentally.For this purpose,1g shaking table tests were conducted under different cyclic loadings for two different saturated granular backfill materials(Soil 1 and Soil 2).In this study,D_(n50) of Soil 1 and Soil 2 are selected as 2.2 cm and 1.0 cm,respectively.During the experiments,accelerations,soil pressures and displacements were measured for each block.Test results pointed out that Soil 2 caused more damage on structures.The measurements for displacement and tilting of each block were discussed in view of“acceptable level of damage in performance-based design”given in PIANC(2001).The result of the study showed that the definitions of damaged levels given in PIANC(2001)were reliable for using in performance-based methods for seismic design of block type quay walls.

Rapid Detection of Oil Pollution in Soil by Using Laser-Induced Breakdown Spectroscopy

Detection of oil pollution in soil has been carried out using laser-induced breakdown spectroscopy（LIBS）. A pulsed neodymium-doped yttrium aluminum garnet（Nd：YAG） laser（1,064 nm, 8 ns, 200 mJ） was focused onto pelletized soil samples. Emission spectra were obtained from oil-contaminated soil and clean soil. The contaminated soil had almost the same spectrum profile as the clean soil and contained the same major and minor elements. However, a C–H molecular band was clearly detected in the oil-contaminated soil, while no C–H band was detected in the clean soil. Linear calibration curve of the C–H molecular band was successfully made by using a soil sample containing various concentrations of oil. The limit of detection of the C–H band in the soil sample was 0.001 mL/g. Furthermore, the emission spectrum of the contaminated soil clearly displayed titanium（Ti） lines, which were not detected in the clean soil. The existence of the C–H band and Ti lines in oil-contaminated soil can be used to clearly distinguish contaminated soil from clean soil. For comparison, the emission spectra of contaminated and clean soil were also obtained using scanning electron microscope-energy dispersive X-ray（SEM/EDX） spectroscopy,showing that the spectra obtained using LIBS are much better than using SEM/EDX, as indicated by the signal to noise ratio（S/N ratio）.

A remote sensing based analysis of climate change in Sikkim supported by evidence from the field

The Himalayas hailed as the‘water towers of the world’feed many perennial rivers which form the lifeline of the Indian sub-continent.Climate change induced rising global temperatures and changing rainfall patterns are currently threatening the glaciers that feed the rivers.The combination of these factors is causing water stresses to a part of the world which is usually considered water abundant.Though there are some large-scale studies done in the Himalayas,regional analysis of changing rainfall patterns and their impacts on vegetation and agriculture is lacking.Here we focus on the Indian state of Sikkim located in the Eastern Himalayas to evaluate these issues using mixed methods.We use satellite data from PERSIANN and MODIS to characterise the regional rainfall,vegetation,and surface temperature trends between 2001 and 2019.While the analysis shows overall declining rainfall trends across most land cover classes,the trends in temperature are mostly positive for the period of study,with winter Land Surface Temperature(LST)values showing the largest area with marginally significant(p<0.1)positive trends.In contrast,such patterns are not observed for agriculture.However,the interviews corroborate that even agriculture is impacted,implying that the trends continue at finer spatial scales too.The lack of government support for adaptation and mitigation is also lamented placing the communities at a precarious position to continuing climate change.

Electronic Band Structure of Carbon Nanotubes with Kekule Structure

Electronic band structure of carbon nanotubes with the Kekule structure is studied by the tight-binding ap-proximation.We give a complete geometrical approach to structural properties of carbon nanotubes with bond alternation,including chiral and achiral tubes.When the Kekule is introduced,all carbon nanotubes become semiconducting with a small band gap at the Fermi level.The band gap of the carbon nanotubes depends only on the difference between C–C bond lengths or the resonance integrals.

Spillovers of US unconventional monetary policy:quantitative easing,spreads,and international financial markets

This study investigates the international spillover effects of US unconventional monetary policy(UMP)-frequently called large-scale asset purchases or quantitative easing(QE)—on advanced and emerging market economies,using structural vector autoregressive models with high-frequency daily data.Blinder(Federal Reserve Bank of St.Louis Rev 92(6):465–479,2010)argued that the QE measures primarily aim to reduce US interest rate spreads,such as term and risk premiums.Considering this argument and recent empirical evidence,we use two spreads as indicators of US UMP:the mortgage and term spreads.Based on data from 20 emerging and 20 advanced countries,our empirical findings reveal that US unconventional monetary policies significantly affect financial conditions in emerging and advanced countries by altering the risktaking behavior of investors.This result suggests that the risk-taking channel plays an important role in transmitting the effects of these policies to the rest of the world.The extent of these effects depends on the type of QE measures.QE measures such as purchases of private sector securities that lower the US mortgage spread exert stronger and more significant spillover effects on international financial markets than those that reduce the US term spread.Furthermore,the estimated financial spillovers vary substantially across countries and between and within the emerging and advanced countries that we examine in this study.

Adakite-like granitoids of Songkultau:A relic of juvenile Cambrian arc in Kyrgyz Tien Shan

The early Paleozoic Terskey Suture zone,located in the southern part of the Northern Tien Shan domain in Kyrgyzstan,comprises tectonic slivers of dismembered ophiolites and associated primitive volcanics and deepmarine sediments.In the Lake Songkul area,early-middle Cambrian pillow basalts are crosscut by the Songkultau intrusion of coarse-grained gneissose quartz diorites and tonalites with geochemical characteristics typical for high-SiO2 adakites(SiO2>56 wt.%,Al2O3>15 wt.%,Na2 O>3.5 wt.%and high Sr/Y and La/Yb ratios).The Songkultau granitoids have positive initialεNd(+3.8 to+6.4)andεHf(+12.3 to+13.5)values indicating derivation from sources with MORB-like isotopic signature.Volcanic formations,surrounding the Songkultau intrusion,have geochemical affinities varying from ocean floor to island arc series.This rock assemblage is interpreted as a relic of an early-middle Cambrian primitive arc where the adakite-like granitoids were derived from partial melting of young and hot subducted oceanic crust.An age of 505 Ma,obtained for the Songkultau intrusion,shows that hot subduction under the Northern Tien Shan continued until middle Cambrian.The primitive arc complexes were obducted onto the Northern Tien Shan domain,where the Andean type continental magmatic arc developed in Cambrian and Ordovician.Formation of the Andean type arc was accompanied by uplift,erosion and deposition of coarse clastic sediments.A depositional age of ca.470 Ma,obtained for the gravellites in the Lake Songkul area,is in agreement with the timing of deposition for lower Ordovician conglomerates elsewhere in the Northern Tien Shan,and corresponds to the main phase of the Andean type magmatism.The Songkultau adakites in association with surrounding ocean floor and island arc formations constitute a relic of a primitive Cambrian arc and represent a juvenile domain of substantial size identified so far within the predominantly crustal-derived terranes of Tien Shan.On a regional scale this primitive arc can be compared with juvenile Cambrian arcs of Kazakhstan,Gorny Altai and Mongolia.

An Anatomical and Radiological Study of Origins of the Arteries Forming the Celiac Trunk: Clinical and Embryological Implications

The blood supply to the most of abdominal organs is provided by the branches of CT. The SMA supply caecum, ascends colon, all of the small bowels except the upper part of duodenum. Knowledge of variable anatomy of celiac axis and SMA may be useful in planning and executing radiological interventions such as celiacography and chemoembolization of hepatic and pancreatic tumors. In this study, the uncommon or low percentage cases of CT and SMA are presented in the light of clinical and embryological information. The celiac axises of a total of 30 adult corpses were examined. Dissections of abdominal region were performed in detail according to Cunningham’s manual. Angiographic images of 100 consecutive adult patients who underwent celiac MDCT angiography were evaluated. During autopsies, an incomplete celiac trunk or bifurcation of celiac trunk associated with the hepatomesenteric and gastrosplenic trunks (0.7%) and a celiacomesenteric trunk associated with high origin superior mesenteric artery and gastrosplenic trunk were detected (0.7%). During MDCT angiography, a case of total absence of celiac trunk associated with a hepatosplenomesenteric trunk (0.7%) and also a case of total absence of celiac trunk alone were observed (0.7%). The persistence or unusual development of ventral splanchnic arteries (VSAs) or ventral longitudinal anastomosis may result in variations or the unusual trunks related to celiac axis and SMA. The anomalous trunks of the CT may be result of either the persistence of some parts of the VSAs or ventral longitudinal anastomose that normally disappear or disappearance of parts that normally persist. The prevalence of unusual trunks of celiac axis and SMA in this study is quite low in literature. These abnormal vessels pose problems for surgeons and radiologists. Such vascular anomalies may cause clinical complications following surgical and radiological procedures such as resection of tumor of the pancreatic head, lymphadenectomy, coeliacography, aortic replacement with reimplantation of the trunk and coembolization of pancreatic and liver tumors.

Clinical characteristics and outcomes of nosocomial COVID-19 in Turkey:A retrospective multicenter study

Objective:To identify the clinical characteristics and outcomes of hospital-acquired SARS-CoV-2 infection during the vaccination period nationwide in Turkey.Methods:COVID-19 patients followed in the pandemic services across Turkey between January 1,2021,and March 31,2022 were investigated retrospectively.Nosocomial COVID-19 was defined as a patient neither diagnosed with COVID-19 nor suspected COVID-19 at the hospital admission and was confirmed COVID-19≥5 days after hospital admission.The primary outcome of this study was in-hospital mortality;demographic features and vaccination status was compared between survivors and non-survivors.Results:During the study period,15573 COVID-19 patients were followed in 18 centers and 543(3.5%)patients were nosocomial COVID-19.Most patients with nosocomial COVID-19(80.4%)were transferred from medical wards.162(29.8%)of the patients with nosocomial COVID-19 admitted to the intensive care unit due to disease severity and 138(25.4%)of the patients died during hospital stay.Advanced age(≥65 years)and number of comorbid diseases(≥2)was found to be associated with mortality in nosocomial COVID-19(OR 1.74,95%CI 1.11-2.74 and OR 1.60,95%CI 1.02-2.56,respectively).Vaccination was associated with survival in nosocomial COVID-19(OR 0.25,95%CI 0.16-0.38).Conclusions:Patients with nosocomial COVID-19 had increased admission to intensive care units and higher mortality rate.Vaccination can decrease the in-hospital mortality rate.

Quantum correlations and entanglement in coupled optomechanical resonators with photon hopping via Gaussian interferometric power analysis

Quantum correlations that surpass entanglement are of great importance in the realms of quantum information processing and quantum computation.Essentially,for quantum systems prepared in pure states,it is difficult to differentiate between quantum entanglement and quantum correlation.Nonetheless,this indistinguishability is no longer holds for mixed states.To contribute to a better understanding of this differentiation,we have explored a simple model for both generating and measuring these quantum correlations.Our study concerns two macroscopic mechanical resonators placed in separate Fabry–Pérot cavities,coupled through the photon hopping process.this system offers a comprehensively way to investigate and quantify quantum correlations beyond entanglement between these mechanical modes.The key ingredient in analyzing quantum correlation in this system is the global covariance matrix.It forms the basis for computing two essential metrics:the logarithmic negativity(E_(N)^(m))and the Gaussian interferometric power(P_(G)^(m)).These metrics provide the tools to measure the degree of quantum entanglement and quantum correlations,respectively.Our study reveals that the Gaussian interferometric power(P_(G)^(m))proves to be a more suitable metric for characterizing quantum correlations among the mechanical modes in an optomechanical quantum system,particularly in scenarios featuring resilient photon hopping.

Caveolin‑1 is critical for hepatic iron storage capacity in the development of nonalcoholic fatty liver disease

Background:Nonalcoholic fatty liver disease(NAFLD)is associated with disordered lipid and iron metabolism.Our previous study has substantiated the pivotal role of Caveolin-1(Cav-1)in protecting hepatocytes and mediating iron metabolism in the liver.This study aimed to explore the specific mechanisms underlying the regulation of iron metabolism by Cav-1 in NAFLD.Methods:Hepatocyte-specific Cav-1 overexpression mice and knockout mice were used in this study.Cav-1-knockdown of RAW264.7 cells and mouse primary hepatocytes were performed to verify the changes in vitro.Moreover,a high-fat diet and palmitic acid plus oleic acid treatment were utilized to construct a NAFLD model in vivo and in vitro,respectively,while a high-iron diet was used to construct an in vivo iron overload model.Besides,iron concentration,the expression of Cav-1 and iron metabolism-related proteins in liver tissue or serum were detected using iron assay kit,Prussian blue staining,Western blotting,immunofluorescence staining,immunohistochemical staining and ELISA.The related indicators of lipid metabolism and oxidative stress were evaluated by the corresponding reagent kit and staining.Results:Significant disorder of lipid and iron metabolism occurred in NAFLD.The expression of Cav-1 was decreased in NAFLD hepatocytes(P<0.05),accompanied by iron metabolism disorder.Cav-1 enhanced the iron storage capacity of hepatocytes by activating the ferritin light chain/ferritin heavy chain pathway in NAFLD,subsequently alleviating the oxidative stress induced by excess ferrous ions in the liver.Further,CD68^(+) CD163^(+) macrophages expressing Cav-1 were found to accelerate iron accumulation in the liver,which was contrary to the effect of Cav-1 in hepatocytes.Positive correlations were also observed between the serum Cav-1 concentration and the serum iron-related protein levels in NAFLD patients and healthy volunteers(P<0.05).Conclusions:These findings confirm that Cav-1 is an essential target protein that regulates iron and lipid metabolic homeostasis.It is a pivotal molecule for predicting and protecting against the development of NAFLD.

Is ypTNM staging a comparable predictor as pTNM staging for survival in non-metastatic rectal cancer after preoperative chemoradiation therapy?

Abstract:Background:The pTNM staging system is widely recognized as the most effective prognostic indicator for cancer.The latest update of this staging system introduced a new pathological staging system(ypTNM)for patients receiving neoadjuvant chemoradiotherapy(NACRT).However,whether the prognostic value of the ypTNM staging system for rectal cancer is similar to that of the pTNM staging system remains unclear.This study was conducted to compare the ypTNM and pTNM staging systems in terms of their prognostic value for patients with nonmetastatic rectal cancer undergoing proctectomy.Material and Methods:This study was conducted at a large teaching hospital.Between January 2014 and December 2022,542 patients with rectal cancer were analyzed(median follow-up period,60 months;range,6–105 months).Of them,258 and 284 were included in the pTNM and ypTNM groups,respectively.Inverse probability of treatment weighting(IPTW)was performed to account for the effects of confounders.Cox proportional-hazards regression was performed for the between-group comparison of overall survival(OS).Results:The crude model revealed that OS was similar between the two groups(p=0.607).After performing IPTW,we found that patients with the same ypTNM-and pTNM-classified stages had similar overall survival(hazard ratio=1.15;95%CI=0.76–1.73;p=0.5074).Conclusions:For patients with rectal cancer who have received preoperative NACRT,the prognostic value of ypTNM staging appears to be similar to that of pTNM staging,mostly because of the downstaging effect of neoadjuvant chemoradiotherapy。

用水热法合成掺杂Pr^(3+)的NiPr_xFe_(2-x)O_4纳米颗粒及其表征

采用水热法制备了掺杂Pr3+的NiPrx Fe2-x O4(x=0.0,0.01,0.025,0.05,0.075,0.1,0.15)纳米颗粒.实验结果表明制备的样品是立方体结构的纳米颗粒,当掺杂量为0<x≤0.1时Pr3+能成功掺杂到NiFe2O4尖晶石晶格内,但掺杂量x>0.1(x=0.15)时会出现杂峰.随着掺杂量从0增加到0.1,样品的平均晶粒尺寸从47nm减小到18nm,饱和磁化强度从55A·m2/kg单调减小至37A·m2/kg,矫顽力从4.7×103 A/m减小到3.4×103 A/m.饱和磁化强度减少的原因主要是由于室温下无磁性的Pr3+代替NiFe2O4中的Fe3+造成的.

Experimental and numerical investigations of interface properties of Ti6Al4V/CP-Ti/Copper composite plate prepared by explosive welding

Explosive welding technique is widely used in many industries.This technique is useful to weld different kinds of metal alloys that are not easily welded by any other welding methods.Interlayer plays an important role to improve the welding quality and control energy loss during the collision process.In this paper,the Ti6Al4V plate was welded with a copper plate in the presence of a commercially pure titanium interlayer.Microstructure details of welded composite plate were observed through optical and scanning electron microscope.Interlayer-base plate interface morphology showed a wavy structure with solid melted regions inside the vortices.Moreover,the energy dispersive spectroscopy analysis in the interlayer-base interface reveals that there are some identified regions of different kinds of chemical equilibrium phases of CueTi,i.e.CuTi,Cu_(2)Ti,CuTi_(2),Cu_(4)Ti,etc.To study the mechanical properties of composite plates,mechanical tests were conducted,including the tensile test,bending test,shear test and Vickers hardness test.Numerical simulation of explosive welding process was performed with coupled Smooth Particle Hydrodynamic method,Euler and Arbitrary Lagrangian-Eulerian method.The multi-physics process of explosive welding,including detonation,jetting and interface morphology,was observed with simulation.Moreover,simulated plastic strain,temperature and pressure profiles were analysed to understand the welding conditions.Simulated results show that the interlayer base plate interface was created due to the high plastic deformation and localized melting of the parent plates.At the collision point,both alloys behave like fluids,resulting in the formation of a wavy morphology with vortices,which is in good agreement with the experimental results.