Combination of dispersive solid phase extraction with dispersive liquid–liquid microextraction for the sequential speciation and preconcentration of Cr(III) and Cr(VI) in water samples prior to graphite furnace atomic absorption spectrometry determination

Li Yao,Yongqun Zhu,Wenzhi Xu,Hong Wang,Xie Wang,Jianhua Zhang,Haitao Liu,Chaowen Lin 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.72 No.-

In this study, the combination of dispersive solid phase extraction (DSPE) with dispersive liquid–liquidmicroextraction (DLLME) was proposed as a novel sequential speciation method for Cr determination bygraphite furnace atomic absorption spectrometry. In thefirst step, the selective extraction of Cr(III) byDSPE was achieved using graphene oxide (GO) nanoparticles as the adsorbent. The difficulty of separationand collection of GO in analytical performance was solved by the introduction of the syringe nanofilter. Then Cr(VI) was enriched by DLLME using [Omim] [PF6] as the extraction solvent. The experimentalparameters affecting the performance of both preconcentration methods were investigated andoptimized. Under the optimal conditions including the initial pH value of 7, 150 mg GO, 2 min ultrasoundtime, 210 mL elution solvent (first step), secondary pH value of 4, 0.15% (m/v) Aliquat-336, 120 mL of[Omim] [PF6] and 3 min ultrasound time (second step), the linear range of 0.06–5 ng/mL (R > 0.997), thelimits of detection of 0.015 and 0.02 ng/mL were achieved for Cr(III) and Cr(VI), respectively. The relativestandard deviations (n = 5) of 0.6 ng/mL Cr(III) and Cr(VI) were 3.2% and 4.6%, respectively. Finally, thisnewly developed method was applied for the speciation and determination of Cr species in differentwater samples and satisfactory results were obtained.

A review of the preparation and applications of MnO2 composites in formaldehyde oxidation

Shengnan Guan,Wenzhi Li,Jianru Ma,Yanyan Lei,Yuanshuai Zhu,Qifu Huang,Xiaomeng Dou 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-

This paper reviews several important preparation methods, and several kinds of MnO2 composites, which is efficient in formaldehyde catalytic oxidation. The preparation of MnO2 composites discussed in this article refer to sol–gel method, rheological phase reaction method, micro-emulsion method, chemical coprecipitation method, solid-phase synthesis and template method. After a presentation of methods for the preparation of MnO2, a review of the performance on formaldehyde catalytic oxidation over (I) manganese oxides; (II) metal–MnO2 oxide composites; (III) graphene–MnO2 composites is provided. The mechanisms for catalytic oxidation of HCHO over MnO2 composites, future directions and potential hotspots are also discussed to facilitate understanding.

Age and Sex Distribution of Chinese Chronic Cough Patients and Their Relationship With Capsaicin Cough Sensitivity

Kefang Lai,Li Long,Fang Yi,Jiaman Tang,Zhe Chen,Fagui Chen,Jianmeng Zhou,Wen Peng,Liting Zhang,Hu Li,Wenzhi Zhan,Ruchong Chen,Wei Luo,Qiaoli Chen,Kian Fan Chung,Nanshan Zhong 대한천식알레르기학회 2019 Allergy, Asthma & Immunology Research Vol.11 No.6

Purpose: An older female predominance has been reported among chronic cough patients in Western countries, which is considered to be associated with a higher cough sensitivity in females. However, the characteristics of Chinese chronic cough patients remain unclear. This study aimed to explore the age and sex distribution as well as their relationship with cough reflex sensitivity to capsaicin in Chinese chronic cough patients. Methods: We analyzed the demographic features of 1,882 consecutive chronic cough patients who attended our cough clinic in Guangzhou, China. Cough sensitivity to capsaicin, which was defined as the lowest concentration of capsaicin causing 5 coughs or more (C5), was measured in 539 of the 1,882 patients and 68 healthy volunteers. Results: The mean age of the patients was 43.0 ± 13.7 years and patients aged <50 years accounted for more than two-thirds of the study population. Around 87% of the patients were never-smokers. The proportion of females (51.5%) was almost equal to that of males (48.5%). The pattern of the age and sex distribution was consistently reflected within most common causes of chronic cough, while a female predominance was shown in patients with coughvariant asthma and patients aged ≥50 years. Female patients had higher cough sensitivity to capsaicin than male patients (log C5: 1.58 ± 0.84 vs. 2.04 ± 0.84 μmol/L, P = 0.001), and patients aged ≥50 years had higher cough sensitivity to capsaicin than patients aged <50 years. Conclusions: In China, patients with chronic cough have a roughly equal sex distribution and a middle-aged predominance, irrespective of a higher cough sensitivity to capsaicin in females and older patients.

Solvated behavior and crystal growth mechanism of erythromycin in aqueous acetone solution

Zhanzhong Wang,Wenzhi Fang,Yan Li 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.1

The solubility of erythromycin acetone solvate and dihydrate was experimentally determined in aqueous acetone mixtures at different temperature. It has been demonstrated that solubility curves of the two solvates intersected at given solvent composition at various temperature, suggesting a transition behavior between two solvates. The induction period of acetone solvate at different supersaturation was measured by the laser monitoring observation technique. Based on classical homogeneous nucleation theory, the solid-liquid interfacial tension and surface entropy factor were calculated from the induction period data. From the surface entropy factor values calculated, together with surface morphology observation by the atomic force microscopy (AFM), the growth mechanism of erythromycin acetone solvate is consistent with continuous growth mode.

Maximal inequalities for some dependent sequences and their applications

Shuhe Hu,Xiaoqin Li,Wenzhi Yang,Xuejun Wang 한국통계학회 2011 Journal of the Korean Statistical Society Vol.40 No.1

In this paper, we obtain the maximal inequalities for linear process, ϕ-mixing sequence and linearly negative quadrant dependent (LNQD) sequence when the rth moments of random variables are finite for r > 2. Applying these maximal inequalities above, we get the Hájek–Rényi-type inequality, strong law of large numbers, strong growth rate and integrability of supremum for these three sequences.

Immunomodulatory biomaterials for implant-associated infections: from conventional to advanced therapeutic strategies

Dong Jiale,Wang Wenzhi,Zhou Wei,Zhang Siming,Li Meng,Li Ning,Pan Guoqing,Zhang Xianzuo,Bai Jiaxiang,Zhu Chen 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Implant-associated infection (IAI) is increasingly emerging as a serious threat with the massive application of biomaterials. Bacteria attached to the surface of implants are often difficult to remove and exhibit high resistance to bactericides. In the quest for novel antimicrobial strategies, conventional antimicrobial materials often fail to exert their function because they tend to focus on direct bactericidal activity while neglecting the modulation of immune systems. The inflammatory response induced by host immune cells was thought to be a detrimental force impeding wound healing. However, the immune system has recently received increasing attention as a vital player in the host’s defense against infection. Anti-infective strategies based on the modulation of host immune defenses are emerging as a field of interest. This review explains the importance of the immune system in combating infections and describes current advanced immune-enhanced anti-infection strategies. First, the characteristics of traditional/conventional implant biomaterials and the reasons for the difficulty of bacterial clearance in IAI were reviewed. Second, the importance of immune cells in the battle against bacteria is elucidated. Then, we discuss how to design biomaterials that activate the defense function of immune cells to enhance the antimicrobial potential. Based on the key premise of restoring proper host-protective immunity, varying advanced immune-enhanced antimicrobial strategies were discussed. Finally, current issues and perspectives in this field were offered. This review will provide scientific guidance to enhance the development of advanced anti-infective biomaterials.

Simultaneous Improvement of Thermal Conductivity and Strength for Commercial A356 Alloy Using Strontium Modification Process

Kang Wang,Wenfang Li,Wenzhi Xu,Shengyu Hou,Shaodong Hu 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

The Aluminum–Silicon (Al–Si) die-casting alloys, such as the commercial A356 alloy, are expected to be used in heat-sinkand the device with high thermal conductivity due to their high production efficiency of casting process. These fields alsorequired them to possess sound mechanical properties. To meet these demands, the Strontium (Sr) was often utilized tomodify the silicon phase. According to our current work, the secondary dendrite arm spacing of the α-Al grains prominentlywas decreased when 0.05%–0.25% strontium was added. The decrease of the secondary dendrite arm spacing (SDAS) lead tothe enhancement of the mechanical strength as well as the improvement of the thermal and electrical conductivity. When theSr dosage was 0.15% in the commercial A356 alloy, the strength and the thermal conductivity of the A356 alloy simultaneouslyreached the maximum value. The improvement of the electrical and thermal conductivity might by contributed by theformation of a good conductor, Al2Si2Srphase, on the Si surface. Further investigations suggested that the improvement ofthermal conductivity was mainly due to the modification effect of Sr on the eutectic Si phase, which enlarged the specificarea between the α-Al/eutectic Si interface. The WDS analysis indicated that the solubility of Si decreased in aluminummatrix by increasing in the Sr dosage. However, the excessive dosage of strontium would result in the coarsening of themodified silicon phase, deteriorating the strength and the thermal and electrical conductivity of the modified A356 alloys.

A new strategy for protein crystallization : Effect of ionic liquids on lysozyme crystallization and morphology

Zhanzhong Wang,Qing Gu,Wenzhi Fang,Yan Li,Jingshu Zhang 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.6

Protein crystallization is a complex physical and chemical process. The high-quality protein crystal is still apersistent bottleneck to the application of X-ray crystallography in structural biology. The additives may promote formationof crystal nucleus and subsequent growth in protein crystallization. As a distinct material, ionic liquids (ILs)have aroused great attention and interest for protein crystallization due to their unique properties. We reviewed the progressof protein crystallization and reported research about protein crystal morphology control by ILs, as crystal growthtemplate, in aqueous solutions. ILs encourage changes in some cases in terms of growth morphology and crystal size. The effect of ILs on lysozyme growth morphology can be attributed to changing interaction among lysozyme moleculesin aqueous solutions. This work can provide some initial insight into the preparation of high quality crystal and thedevelopment of new crystal form.

Prediction and Analysis of Diesel Engine Combustion Noise Using Transfer Function Method

Wei Zhaoyi,Zheng Liang,Huang Li,Gao Wenzhi,Li Yong,Zhao Xinying,Liu Rui 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.3

With the increasingly strict emission regulations, the combustion noise has become an important factor restricting diesel engine development. Therefore, it is necessary to study the transfer function and prediction of combustion noise and to control it from the design stage. This paper proposes a method to calculate the combustion noise transfer function. An electronically controlled common rail diesel engine (D19TCI) was selected as the research object. It was tested for in-cylinder pressure and sound pressure across different engine operating conditions. The original signal was preprocessed using time synchronization and least squares polynomial fitting, and the diesel engine combustion noise transfer function was obtained based on motor tests and different injection strategies. The research verified the existence of a transfer relationship between the in-cylinder pressure and surface radiation combustion noise in all directions in the same engine. In addition, the prediction accuracy of the combustion noise obtained using the transfer function was verified. The experimental results show that the combustion noise transfer function obtained using the multiple linear regression main-injection strategy has better consistency result than other strategies, and the results also provide new ideas and methods for optimization design of diesel engine noise reduction.

Preparation and Self-Healing Behaviors of Poly(acrylic acid)/Cerium Ions Double Network Hydrogels

Hongwei Zhou,Guohe Xu,Jie Li,Shihao Zeng,Xiaolong Zhang,Zhaohui Zheng,Xiaobin Ding,Weixing Chen,Qiguan Wang,Wenzhi Zhang 한국고분자학회 2015 Macromolecular Research Vol.23 No.12

This work aims at developing an approach to poly(acrylic acid)/cerium ions (PAA/cerium ions) double network hydrogels and exploring the self-healing properties of the hydrogels, with expectation to provide some clues for constructing new healable gel actuators and enrich the family of self-healable hydrogels. The hydrogel is covalently crosslinked by a traditional crosslinking agent N,N'-methylene bis-acrylamide to form the first network and further physically crosslinked by the ionic interaction between cerium ions and the carboxyl groups in the hydrogel network. The preparation method and self-healing behaviors of the hydrogels are investigated.