慢性肾衰竭患者幽门螺旋杆菌感染与血浆脂蛋白相关磷脂酶A2及颈动脉粥样硬化的关系

目的探讨慢性肾衰竭(CRF)患者幽门螺旋杆菌(Hp)感染与血浆脂蛋白相关磷脂酶A_2(Lp-PLA_2)水平及颈动脉粥样硬化(CAS)的关系。方法选取CRF患者200例,根据~(14)C尿素呼气试验分为CRF合并Hp感染组(CRF-Hp组,n=119)和CRF未合并Hp感染组(CRF-nHp组,n=81)。将CRF-Hp组按CAS程度又分为3个亚组:颈动脉内膜中膜厚度(CIMT)增厚组、稳定性斑块组和不稳定性斑块组。采用酶联免疫吸附法测定血浆Lp-PLA_2水平,用高分辨二维超声技术检测CIMT、粥样硬化斑块。分析CRF患者Hp感染与血浆Lp-PLA_2水平、CIMT、粥样硬化斑块稳定性的关系。结果 CRF-Hp组血浆Lp-PLA_2水平、CIMT与CRF-nHp组比较差异均有统计学意义(P0.01)。CRF-Hp组和CRF-nHp组CAS类型的构成比差异有统计学意义(χ~2=15.637,P=0.0004)。在CRF-Hp组3个亚组中,不稳定性斑块组、稳定性斑块组、CIMT增厚组血浆Lp-PLA_2水平比较差异均有统计学意义(P0.01)。Pearson相关分析显示,CRF-Hp组血浆Lp-PLA_2水平与CIMT呈正相关(r=0.649,P0.01)。结论CRF患者Hp感染可能通过影响血浆Lp-PLA_2水平使CIMT增厚,并导致CAS斑块的不稳定性增加,从而促进CAS的发生和发展。     

冠状动脉粥样硬化性心脏病患者小而密低密度脂蛋白、脂蛋白相关磷脂酶A2和组织蛋白酶S 水平与颈动脉粥样硬化的相关性

目的探讨分析冠状动脉粥样硬化性心脏病(冠心病)患者血清小而密低密度脂蛋白(sdLDL)、脂蛋白相关磷脂酶A2(Lp-PLA2)和组织蛋白酶S(CatS)水平与颈动脉粥样硬化的相关性。方法选取2017年1月—2018年6月收治的冠心病患者172例作为冠心病组,根据颈动脉狭窄程度分为轻度(n=59)、中度(n=65)和重度狭窄(n=48)3个亚组,另选取同期体检健康者50人为对照组,采用酶联免疫吸附试验(ELISA)法检测血清sdLDL、Lp-PLA2和CatS水平。采用Pearson相关性分析观察指标和颈动脉狭窄程度的相关性,多元线性回归分析观察指标与颈动脉粥样硬化的关系。结果冠心病组sdLDL、Lp-PLA2和CatS水平高于对照组(均P0.05);轻度、中度和重度狭窄3个亚组患者sdLDL、Lp-PLA2和CatS水平的差异有统计学意义(均P0.05),狭窄程度越重,sdLDL、Lp-PLA2和CatS水平增高越明显;Pearson相关性分析显示,sdLDL、Lp-PLA2和CatS水平与狭窄程度呈正相关(分别r=0.665,0.536,0.519,均P0.05);多元线性逐步回归分析显示,血清sdLDL、Lp-PLA2和CatS是影响颈动脉狭窄程度的因素。结论冠心病患者血清sdLDL、Lp-PLA2和CatS水平越高,颈动脉粥样硬化程度越严重。     

颈动脉彩色多普勒对老年冠心病患者颈动脉粥样硬化斑块的评估价值

目的 探讨颈动脉彩色多普勒对老年冠心病患者颈动脉粥样硬化斑块的评估价值。方法 颈动脉粥样硬化冠心病老年患者102例根据冠状动脉造影结果分为冠脉单支病变组71例、冠脉多支病变组31例。所有患者进行颈动脉彩色多普勒，评估颈动脉粥样硬化斑块性质、斑块面积、颈动脉内膜中层厚度、颈动脉狭窄程度、颈动脉血流参数。比较不同斑块性质、不同颈动脉狭窄程度患者的1年内不良预后情况。结果 冠脉多支病变组中不稳定型斑块率(64.52%)显著高于冠脉单支病变组(32.39%,P<0.05)。冠脉多支病变组颈动脉粥样硬化斑块面积、颈动脉分叉处和颈内动脉的内膜中层厚度均显著大于冠脉单支病变组(P<0.05)。冠脉单支病变组轻度狭窄占52.11%,中度狭窄占28.17%,重度狭窄占19.72%;冠脉多支病变组轻度狭窄占19.35%,中度狭窄占51.61%,重度狭窄占29.03%;两组差异显著(Z=9.683,P<0.05)。冠脉多支病变组颈动脉收缩期峰值流速(Vs)、阻力指数(RI)均显著大于冠脉单支病变组(P<0.05)。冠脉多支病变、不稳定型斑块、颈动脉重度狭窄患者1年内心肌梗死再发、短暂...     

老年脑梗死患者血浆MMP-9、CD105和TIMP-1的表达水平及其与颈动脉粥样硬化斑块稳定性的相关性

目的探讨老年脑梗死患者血浆中基质金属蛋白酶(MMP)-9、CD105及基质金属蛋白酶组织抑制剂(TIMP)-1的表达及其与颈动脉粥样硬化斑块稳定性的相关性。方法选择60例老年脑梗死患者为研究组,同期60例健康体检者为对照组,采用酶联免疫吸附法测定血浆MMP-9、CD105及TIMP-1的表达水平,颈动脉彩色多普勒超声检查患者颈动脉粥样硬化斑块稳定性,并行相关性分析。结果研究组患者的颈动脉粥样硬化斑块检出率86.67%明显高于对照组28.33%(c~2=41.773,P=0.000)。研究组患者的血浆MMP-9表达水平明显高于对照组,而CD105、TIMP-1表达水平明显低于对照组(P<0.01)。不稳定斑块组患者的血浆MMP-9表达水平明显高于对照组,而CD105、TIMP-1表达水平明显低于稳定斑块组(P<0.01)。相关性分析显示血浆MMP-9表达水平与颈动脉粥样硬化斑块稳定性呈正相关(r=0.305,P<0.05),CD105、TIMP-1表达水平与颈动脉粥样硬化斑块稳定性呈负相关(r=-0.336、-0.371,P<0.05),老年脑梗死患者血浆MMP-9、CD105及TIMP-1的表达与颈动脉粥样硬化斑块稳定性密切相关(P<0.05)。结论老年脑梗死患者颈动脉粥样硬化斑块发生率增高,血浆MMP-9水平升高,与颈动脉粥样硬化斑块稳定性正相关,CD105和TIMP-1降低与颈动脉粥样硬化斑块稳定性负相关。     

原发性高血压患者颈动脉粥样硬化与幽门螺杆菌感染的相关性研究

目的探讨原发性高血压(EH)患者颈动脉粥样硬化(CAS)与幽门螺杆菌(Hp)感染的相关性。方法选择2012—2013年我院收治的EH患者150例为EH组,同期在我院体检健康者50例为对照组。检测两组受试者的颈动脉内膜中层厚度(CAIMT)、幽门螺杆菌抗体(Hp-IgG)、血脂及血清高敏C反应蛋白(hs-CRP)、同型半胱氨酸(HCY)水平。结果根据CAIMT和Hp-IgG检查结果将EH组患者分为CAIMT增厚组89例和CAIMT非增厚组61例,Hp感染组67例和Hp非感染组83例。EH组CAIMT1.0 mm者所占比例(59.3%)和Hp-IgG阳性者所占比例(44.7%)均高于对照组(12.0%,28.0%)(P0.05)。CAIMT增厚组Hp-IgG阳性者所占比例(55.1%)高于CAIMT非增厚组(29.5%)(P0.05),Hp感染组CAIMT1.0 mm者所占比例(73.1%)高于Hp非感染组(48.2%)(P0.05)。直线相关分析结果显示,CAIMT增厚与Hp感染率呈正相关(r=0.787,P0.01)。Hp感染组血清TG、TC、LDL-C、HCY、hs-CRP高于Hp非感染组,HDL-C水平低于Hp非感染组(P0.01)。结论 EH患者CAS的发生与Hp感染有关,Hp感染可能通过影响机体炎性反应、血脂代谢及HCY水平促进CAS的发生和发展,清除或预防Hp感染可能是防治EH患者发生CAS的策略之一。     

慢性幽门螺杆菌感染对脑梗死复发及血流动力学的影响

目的分析慢性幽门螺杆菌(HP)感染对脑梗死复发及血流动力学的影响。方法 172例脑梗死患者按照是否感染HP分为感染组82例和非感染组90例,并回顾性比较两组的一般资料、复发情况、颈动脉狭窄和颈动脉粥样硬化程度及血流动力学变化。结果感染组和非感染组年龄、性别、体质指数(BMI)、吸烟、饮酒、高血压、高血脂和高血糖的比例均无统计学差异(P0.05),感染组超敏C反应蛋白(hs-CRP)水平高于非感染组(P0.01)。感染组5年内的脑梗死复发率和死亡率〔分别为43.34%(38例)和15.85%(13例)〕明显高于非感染组〔21.11%(19例)和5.56%(5例)〕(P0.01或P0.05)。感染组重度和中度颈动脉狭窄及中度和重度颈动脉狭窄总和均明显高于非感染组(P0.05)。与非感染组相比,感染组脑梗死复发患者重度和中度颈动脉狭窄总和患者明显增多(P0.01)。感染组重度颈动脉粥样硬化及中度和重度颈动脉粥样硬化总和均明显高于非感染组(P0.01或P0.05)。但与非感染组相比,感染组脑梗死复发患者中度颈动脉狭窄明显增多(P0.05)。两组大脑前动脉(ACA)、大脑后动脉(PCA)、两侧PCA收缩峰流速(Vs)比值(RVACA)、两侧PCA Vs比值(RVPCA)、平均血流量(Qm)和脉动指数(PI)差异不明显(P0.05),但感染组大脑中动脉(MCA)和颈内动脉末端(TICA)平均血流速度较非感染组显著降低(P0.01),而特性阻抗(Zc)和动态阻力(DR)水平明显升高(P0.01)。结论 HP感染可影响脑梗死患者血流动力学,并且可能通过影响动脉粥样硬化的形成进一步促进脑梗死复发。     

颈动脉超声检查在缺血性脑血管病分型诊断中的应用价值

目的探讨颈动脉超声在缺血性脑血管病分型诊断中的应用价值。方法选取2012年7月—2014年4月我院收治的100例缺血性脑血管病病人(观察组)作为研究对象,同时选取100名健康体检者作为对照组。观察两组动静脉粥样硬化斑块检出、分型及颈动脉内中膜厚度(IMT)等情况。结果观察组颈动脉斑块发生率、多发斑块发生率显著高于对照组(P0.05),无斑块数明显少于对照组(P0.05)。观察组软斑、复合斑检出率明显高于对照组(P0.05),硬斑显著少于对照组(P0.05)。观察组IMT为(1.03±0.22)mm,大于对照组的(0.67±0.23)mm(P0.05)。100例受检病人,32例形成粥样硬化斑块且造成管腔狭窄,狭窄率32.0%,其中狭窄程度为轻度19例,中度8例,重度3例,闭塞2例。结论对于缺血性脑血管病病人而言,颈动脉超声检查能有效、快速检出颈动脉粥样硬化程度,对斑块类型、分布作出鉴别,是脑血管疾病优良的检测手段。     

颈动脉斑块超声与冠状动脉狭窄关系分析

目的通过颈动脉超声及冠状动脉造影检测,探讨颈动脉斑块与冠状动脉狭窄之间的关系。方法入选105例拟诊为冠状动脉粥样硬化性心脏病(冠心病)的患者,根据患者冠状动脉造影结果将分为正常组(n=15)和病变组(n=90),病变组根据病变程度分为轻度病变组(n=18),中度病变组(n=40)及重度病变组(n=32)。颈动脉超声检查颈动脉斑块面积、数目、血管内中膜厚度(IMT)情况。结果 105例患者,经颈动脉超声检测80例有颈动脉斑块:正常组有颈动脉斑块者6例(40.0%),病变组72例(80.0%)。颈动脉狭窄者49例,其中轻度狭窄者18例,中度狭窄者22例,重度狭窄者9例。冠状动脉造影正常组与各病变组之间颈动脉斑块面积、斑块数目、IMT相比较,病变组患者颈动脉斑块面积、斑块数目、IMT均明显高于正常组,差异均有统计学意义(P0.05),且随者病变程度的增加,斑块面积、斑块数目、IMT也呈增加趋势(P均0.05)。颈动脉狭窄率随冠状动脉的狭窄程度的增加而升高,差异有统计学意义(P0.05)。结论颈动脉硬化形成斑块随冠状动脉狭窄严重程度呈增加趋势,临床中可以应用颈动脉超声检查来预测冠状动脉病变。     

颈动脉粥样硬化与脑梗死复发的关系研究

目的探讨颈动脉粥样硬化与脑梗死复发的关系。方法采用彩色多普勒超声对278例脑梗死患者的颈动脉进行检测,并随访18个月,脑梗死复发64例(复发组),脑梗死无复发214例(无复发组),比较2组患者颈动脉粥样硬化的特征。结果复发组患者高血压、高胆固醇血症、糖尿病明显高于无复发组(P0.05,P0.01)。颈动脉中、重度狭窄及闭塞患者脑梗死复发率明显高于无颈动脉粥样硬化改变及颈动脉轻度狭窄患者(P0.05)。软斑患者脑梗死复发率明显高于无斑块及硬斑患者(P0.05)。结论颈动脉粥样硬化与脑梗死的复发密切相关,颈动脉粥样硬化的严重程度是脑梗死复发的危险因素,可作为脑梗死复发的预测指标。     

基质金属蛋白酶-9与颈动脉粥样硬化斑块稳定性的关系

目的研究基质金属蛋白酶(MMP)-9与颈动脉粥样硬化斑块稳定性的关系。方法应用彩色多普勒超声仪探测48例颈动脉粥样硬化患者(ACA组)及20例健康体检者(NC组)的双侧颈动脉粥样硬化情况,采用酶联免疫吸附法检测各组血清MMP-9水平。结果 NC组未检出颈动脉粥样硬化斑块。ACA组血清MMP-9水平明显高于NC组(P0.05);ACA组中,易损斑块亚组血清MMP-9水平明显高于稳定斑块亚组,稳定斑块亚组血清MMP-9水平明显高于无斑块亚组(均P0.05)。结论 MMP-9水平升高可作为反映颈动脉粥样硬化斑块稳定性的血清学检测指标。     

Metastable Materials Accessed under Moderate Pressure Conditions (P ≤ 3.5 GPa) in a Piston-Cylinder Press

In this review, we describe different families of metastable materials, some of them with relevant technological applications, which can be stabilized at moderate pressures 2–3.5 GPa in a piston-cylinder press. The synthesis of some of these systems had been previously reported under higher hydrostatic pressures (6–10 GPa), but can be accessed under milder conditions in combination with reactive precursors prepared by soft-chemistry techniques. These systems include perovskites with transition metals in unusual oxidation states (e.g., RNiO₃ with Ni³⁺, R = rare earths); double perovskites such as RCu₃Mn₄O₁₂ with Jahn–Teller Cu²⁺ ions at A sites, pyrochlores derived from Tl₂Mn₂O₇ with colossal magnetoresistance, pnictide skutterudites M_xCo₄Sb₁₂ (M = La, Yb, Ce, Sr, K) with thermoelectric properties, or metal hydrides Mg₂MH_x (M = Fe, Co, Ni) and AMgH₃ (A: alkali metals) with applications in hydrogen storage. The availability of substantial amounts of sample (0.5–1.5 g) allows a complete characterization of the properties of interest, including magnetic, transport, thermoelectric properties and so on, and the structural characterization by neutron or synchrotron X-ray diffraction techniques.     

Maximum Achievable N Content in Atom-by-Atom Growth of Amorphous Si-B-C-N Materials

Amorphous Si-B-C-N alloys can combine exceptional oxidation resistance up to 1500 °C with high-temperature stability of superior functional properties. Because some of these characteristics require as high N content as possible, the maximum achievable N content in amorphous Si-B-C-N is examined by combining extensive ab initio molecular dynamics simulations with experimental data. The N content is limited by the formation of unbonded N₂ molecules, which depends on the composition (most intensive in C rich materials, medium in B rich materials, least intensive in Si-rich materials) and on the density (increasing N₂ formation with decreasing packing factor when the latter is below 0.28, at a higher slope of this increase at lower B content). The maximum content of N bonded in amorphous Si-B-C-N networks of lowest-energy densities is in the range from 34% to 57% (materials which can be grown without unbonded N₂) or at most from 42% to 57% (at a cost of affecting materials characteristics by unbonded N₂). The results are important for understanding the experimentally reported nitrogen contents, design of stable amorphous nitrides with optimized properties and pathways for their preparation, and identification of what is or is not possible to achieve in this field.     

An Update Review on N-Type Layered Oxyselenide Thermoelectric Materials

Compared with traditional thermoelectric materials, layered oxyselenide thermoelectric materials consist of nontoxic and lower-cost elements and have better chemical and thermal stability. Recently, several studies on n-type layered oxyselenide thermoelectric materials, including BiCuSeO, Bi₂O₂Se and Bi₆Cu₂Se₄O₆, were reported, which stimulates us to comprehensively summarize these researches. In this short review, we begin with various attempts to realize an n-type BiCuSeO system. Then, we summarize several methods to optimize the thermoelectric performance of Bi₂O₂Se, including carrier engineering, band engineering, microstructure design, et al. Next, we introduce a new type of layered oxyselenide Bi₆Cu₂Se₄O₆, and n-type transport properties can be obtained through halogen doping. At last, we propose some possible research directions for n-type layered oxyselenide thermoelectric materials.     

Drastic Dependence of the pH Sensitivity of Fe2O3-Bi2O3-B2O3 Hydrophobic Glasses with Composition

Fe₂O₃-Bi₂O₃-B₂O₃ (FeBiB) glasses were developed as novel pH responsive hydrophobic glasses. The influence of the glass composition on the pH sensitivity of FeBiB glasses was investigated. The pH sensitivity drastically decreased with decreasing B₂O₃ content. A moderate amount of Fe₂O₃ and a small amount of B₂O₃ respectively produces bulk electronic conduction and a pH response on glass surfaces. Because the remaining components of the glass can be selected freely, this discovery could prove very useful in developing novel pH glass electrodes that are self-cleaning and resist fouling.     

Atomic Layer Deposition of Ultrathin La2O3/Al2O3 Nanolaminates on MoS2 with Ultraviolet Ozone Treatment

Due to the chemically inert surface of MoS₂, uniform deposition of ultrathin high-κ dielectric using atomic layer deposition (ALD) is difficult. However, this is crucial for the fabrication of field-effect transistors (FETs). In this work, the atomic layer deposition growth of sub-5 nm La₂O₃/Al₂O₃ nanolaminates on MoS₂ using different oxidants (H₂O and O₃) was investigated. To improve the deposition, the effects of ultraviolet ozone treatment on MoS₂ surface are also evaluated. It is found that the physical properties and electrical characteristics of La₂O₃/Al₂O₃ nanolaminates change greatly for different oxidants and treatment processes. These changes are found to be associated with the residual of metal carbide caused by the insufficient interface reactions. Ultraviolet ozone pretreatment can substantially improve the initial growth of sub-5 nm H₂O-based or O₃-based La₂O₃/Al₂O₃ nanolaminates, resulting in a reduction of residual metal carbide. All results indicate that O₃-based La₂O₃/Al₂O₃ nanolaminates on MoS₂ with ultraviolet ozone treatment yielded good electrical performance with low leakage current and no leakage dot, revealing a straightforward approach for realizing sub-5 nm uniform La₂O₃/Al₂O₃ nanolaminates on MoS₂.     

Synergistic Effects of Pr6O11 and Co3O4 on Electrical and Microstructure Features of ZnO-BaTiO3 Varistor Ceramics

This paper investigated the effects of Pr₆O₁₁ and Co₃O₄ on the electrical properties of ZnO-BaTiO₃ varistor ceramics. The Pr₆O₁₁ doping has a notable influence on the characteristics of the nonlinear coefficient, varistor voltage, and leakage current where the values varied from 2.29 to 2.69, 12.36 to 68.36 V/mm and 599.33 to 548.16 µA/cm², respectively. The nonlinear varistor coefficient of 5.50 to 7.15 and the varistor voltage of 7.38 to 8.10 V/mm was also influenced by the use of Co₃O₄ as a dopant. When the amount of Co₃O₄ was above 0.5 wt.%, the leakage current increased from 202.41 to 302.71 μA/cm². The varistor ceramics with 1.5 wt.% Pr₆O₁₁ shows good nonlinear electrical performance at higher breakdown voltage and reduced the leakage current of the ceramic materials. Besides, the varistor sample that was doped with 0.5 wt.% Co₃O₄ was able to enhance the nonlinear electrical properties at low breakdown voltage with a smaller value of leakage current.     

The Formation of Cr-Al Spinel under a Reductive Atmosphere

In the present work, for the first time, the possibility of formation of CrAl₂O₄ was shown from the equimolar mixture of co-precipitated Al₂O₃ and Cr₂O₃ oxides under a reductive environment. The crystallographic properties of the formed compound were calculated using the DICVOL procedure. It was determined that it has a cubic crystal structure with space group Fd-3m and a unit cell parameter equal to 8.22(3) Å. The formed CrAl₂O₄ is not stable under ambient conditions and easily undergoes oxidation to α-Al₂O₃ and α-Cr₂O₃. The overall sequence of the phase transformations of co-precipitated oxides leading to the formation of spinel structure is proposed.     

High-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement

Al₂O₃-CaO-Cr₂O₃ castables are used in various furnaces due to excellent corrosion resistance and sufficient early strength, but toxic Cr(VI) generation during service remains a concern. Here, we investigated the relative reactivity of analogous Cr(III) phases such as Cr₂O₃, (Al_1−xCr_x)₂O₃ and in situ Cr(III) solid solution with the calcium aluminate cement under an oxidizing atmosphere at various temperatures. The aim is to comprehend the relative Cr(VI) generation in the low-cement castables (Al₂O₃-CaO-Cr₂O₃-O₂ system) and achieve an environment-friendly application. The solid-state reactions and Cr(VI) formation were investigated using powder XRD, SEM, and leaching tests. Compared to Cr₂O₃, the stability of (Al_1−xCr_x)₂O₃ against CAC was much higher, which improved gradually with the concentration of Al₂O₃ in (Al_1−xCr_x)₂O₃. The substitution of Cr₂O₃ with (Al_1−xCr_x)₂O₃ in the Al₂O₃-CaO-Cr₂O₃ castables could completely inhibit the formation of Cr(VI) compound CaCrO₄ at 500–1100 °C and could drastically suppress Ca₄Al₆CrO₁₆ generation at 900 to 1300 °C. The Cr(VI) reduction amounting up to 98.1% could be achieved by replacing Cr₂O₃ with (Al_1−xCr_x)₂O₃ solid solution. However, in situ stabilized Cr(III) phases as a mixture of (Al_1−xCr_x)₂O₃ and Ca(Al_12−xCr_x)O₁₉ solid solution hardly reveal any reoxidation. Moreover, the CA₆ was much more stable than CA and CA₂, and it did not participate in any chemical reaction with (Al_1−xCr_x)₂O₃ solid solution.     

Corrosion Properties of Cr27Fe24Co18Ni26Nb5 Alloy in 1 N Sulfuric Acid and 1 N Hydrochloric Acid Solutions

The composition of the Cr₂₇Fe₂₄Co₁₈Ni₂₆Nb₅ high-entropy alloy was selected from the FCC phase in a CrFeCoNiNb alloy. The alloy was melted in an argon atmosphere arc-furnace, followed by annealing in an air furnace. The dendrites of the alloy were in the FCC phase, and the eutectic interdendrites of the alloy comprised HCP and FCC phases. The microstructures and hardness of this alloy were examined; the results indicated that this alloy was very stable. This microstructure and hardness of the alloy almost remained the same after annealing at 1000 °C for 24 h. The polarization behaviors of Cr₂₇Fe₂₄Co₁₈Ni₂₆Nb₅ alloy in 1 N sulfuric acid and 1 N hydrochloric acid solutions were measured. Both the corrosion potential and the corrosion current density of the Cr₂₇Fe₂₄Co₁₈Ni₂₆Nb₅ alloy increased with increasing test temperatures. The activation energies of the Cr₂₇Fe₂₄Co₁₈Ni₂₆Nb₅ alloy in these two solutions were also calculated.     

Pilot-Scale Studies of WO3/S-Doped g-C3N4 Heterojunction toward Photocatalytic NOx Removal

Due to the rising concentration of toxic nitrogen oxides (NO_x) in the air, effective methods of NO_x removal have been extensively studied recently. In the present study, the first developed WO₃/S-doped g-C₃N₄ nanocomposite was synthesized using a facile method to remove NOx in air efficiently. The photocatalytic tests performed in a newly designed continuous-flow photoreactor with an LED array and online monitored NO₂ and NO system allowed the investigation of photocatalyst layers at the pilot scale. The WO₃/S-doped-g-C₃N₄ nanocomposite, as well as single components, were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller surface area analysis (BET), X-ray fluorescence spectroscopy (XRF), X-ray photoemission spectroscopy method (XPS), UV–vis diffuse reflectance spectroscopy (DR/UV–vis), and photoluminescence spectroscopy with charge carriers’ lifetime measurements. All materials exhibited high efficiency in photocatalytic NO₂ conversion, and 100% was reached in less than 5 min of illumination under simulated solar light. The effect of process parameters in the experimental setup together with WO₃/S-doped g-C₃N₄ photocatalysts was studied in detail. Finally, the stability of the composite was tested in five subsequent cycles of photocatalytic degradation. The WO₃/S-doped g-C₃N₄ was stable in time and did not undergo deactivation due to the blocking of active sites on the photocatalyst’s surface.