Plasma-assisted ammonia synthesis in a packed-bed dielectric barrier discharge reactor:roles of dielectric constant and thermal conductivity of packing materials

In this article,plasma-assisted NH;synthesis directly from N;and H;over packing materials with different dielectric constants(BaTiO_(2),TiO_(2) and SiO_(2))and thermal conductivities(Be O,Al N and Al_(2)O_(2))at room temperature and atmospheric pressure is reported.The higher dielectric constant and thermal conductivity of packing material are found to be the key parameters in enhancing the NH;synthesis performance.The NH;concentration of 1344 ppm is achieved in the presence of BaTiO_(2),which is 106%higher than that of SiO_(2),at the specific input energy(SIE)of 5.4 k J·l^(-1).The presence of materials with higher dielectric constant,i.e.BaTiO_(2) and TiO_(2)in this work,would contribute to the increase of electron energy and energy injected to plasma,which is conductive to the generation of chemically active species by electron-impact reactions.Therefore,the employment of packing materials with higher dielectric constant has proved to be beneficial for NH;synthesis.Compared to that of Al_(2)O_(3),the presence of Be O and Al N yields 31.0%and 16.9%improvement in NH;concentration,respectively,at the SIE of5.4 k J·l^(-1).The results of IR imaging show that the addition of Be O decreases the surface temperature of the packed region by 20.5%to 70.3℃ and results in an extension of entropy increment compared to that of Al_(2)O_(3),at the SIE of 5.4 k J·l^(-1).The results indicate that the presence of materials with higher thermal conductivity is beneficial for NH;synthesis,which has been confirmed by the lower surface temperature and higher entropy increment of the packed region.In addition,when SIE is higher than the optimal value,further increasing SIE would lead to the decrease of energy efficiency,which would be related to the exacerbation in reverse reaction of NH;formation reactions.

Application and Care of Two Kinds of Sphenoid Sinus Packing Materials after Pituitary Tumor Resection with the Transnasal Endoscopic Approach

Background: Neuroendoscopic transsphenoidal approach for resection of pituitary adenomas has the advantages of less damage, fewer complications, and a faster recovery than the traditional approach and has beening favored by neurosurgeons. However, there has no standard method of selecting suitable packing materials after the operation to relieve pain in patients and achieve the ideal hemostatic effect. We compared the postoperative complications and treatment effects of two different packing materials in patients with pituitary adenomas. Objective: To investigate the advantages and disadvantages of using a catheter balloon and iodoform gauze for hemostasis in patients undergoing pituitary tumor resection by neuroendoscopic transsphenoidal approach. Materials and Methods: We retrospectively analyzed these data of 48 cases treated with pituitary adenoma resection by the single nasal approach from January 2018 to October 2019 in Sun Yat-sen University Cancer Center. According to the type of sphenoid sinus packing material used, these patients were divided into balloon tamponade oppression group (24 cases) and tela iodoformum oppression group (24 cases), respectively. The balloon tamponade oppression group received catheter balloon tamponade oppression hemostasis, and the tela iodoformum oppression group underwent tela iodoformum oppression hemostasis. The outcomes and complications were compared between the two groups in which two kinds of sphenoid sinus packing materials were used for hemostasis after tumor resection by transnasal endoscopic approach. For the catheter balloon compression hemostasis method, on account of the plasticity of the balloon, the volume of water in the balloon can be adjusted according to the size of the patient’s own sphenoid cavity. The amount of bleeding and several complications in terms of discomfort during placement and removal of the packing material, rebleeding after removal of the packing, cerebrospinal fluid rhinorrhea and electrolyte disturbance are compared between the two groups. Results: 48 patients were enrolled. The two groups’ data of patients were similar in age structure, sex ratio, tumor size at baseline and so on. No complications, such as abscess formation, were found in both groups. The success rate in the compression with catheter balloon group was 100% (24 of 24 patients);and in the iodoform gauze group 83.33% (20 of 24 patients). A catheter balloon was more successful in stopping bleeding at early stage than iodoform gauze. There were no statistically significant differences in the hospitalization stay time, operating day to discharge day and tampon indwelling time (P > 0.05). There were also no significant differences in pairwise comparison between the catheter balloon group and iodoform gauze groups in the incidence of cerebrospinal fluid rhinorrhea or electrolyte disturbance between the two groups (P > 0.05). The incidence of headache in the catheter balloon group was statistically significantly lower than that in the iodoform gauze group (P < 0.05). Conclusion: In patients undergoing endoscopic pituitary tumor resection, compression and hemostasis by means of catheterization expansion lead to lower rates of injury and complications and have a good effect, so this method is worthy of being recommended for clinical practice.

Estimating the grain size of microgranular material using laser-induced breakdown spectroscopy combined with machine learning algorithms

Recent work has validated a new method for estimating the grain size of microgranular materials in the range of tens to hundreds of micrometers using laser-induced breakdown spectroscopy(LIBS).In this situation,a piecewise univariate model must be constructed to estimate grain size due to the complex dependence of the plasma formation environment on grain size.In the present work,we tentatively construct a unified calibration model suitable for LIBS-based estimation of those grain sizes.Specifically,two unified multivariate calibration models are constructed based on back-propagation neural network(BPNN)algorithms using feature selection strategies with and without considering prior information.By detailed analysis of the performances of the two multivariate models,it was found that a unified calibration model can be successfully constructed based on BPNN algorithms for estimating the grain size in the range of tens to hundreds of micrometers.It was also found that the model constructed with a priorguided feature selection strategy had better prediction performance.This study has practical significance in developing the technology for material analysis using LIBS,especially when the LIBS signal exhibits a complex dependence on the material parameter to be estimated.

SYNTHESIS OF INTERFERON-α_A MONOCLONAL ANTIBODY PACKING MATERIAL IN HIGH-PERFORMANCE AFFINITY CHROMATOGRAPHY AND PURIFICATION OF RECOMBINANT HUMAN INTERFERON-α_A

A new way for the synthesis of human interferon—α;monoclonal antibody （IFN-α;-McAb） bound to silica gel packing material in high-performance affinity chromatography （HPAFC） has been developed. The high coupling efficiency and specific activity of IFN—α;-McAb can be obtained by activated diol-silica gel with activating agent. After purification using this packing material in HPAFC, the specific activity of recombinant human interferon-α;（rIFN-α;） rose up to 1.03×10;IU/mg protein and the purification efficiency is appoximately 100 times.

Study on the Adsorption of Preservatives by Eyeliner Pen Packaging Materials

In order to study adsorption of preservatives by eyeliner pen package,the chemical compositions of the commercially available Eyeliner package were analyzed by infrared spectrometer.It was found that these package components were PP,PET,modified PP,modified PET,ABS,nylon,PU and so on.The adsorption effects of these components on three preservatives,i.e.phenoxyethanol,Methyl paraben and Propyl paraben have been further studied by high performance liquid chromatography.The results demonstrated that the four chemical materials PET,PP,modified PP and ABS had no adsorption on the above three preservatives.However,the component named of water diversion core which was composed of modified PET,and nylon-made cotton head have been observed of slight adsorption in this study.And components as the function of preventing liquid leakage,which was made of PU,have presented the most serious adsorption on these three preservatives,with the adsorption order as Propyl Paraben>Methyl Paraben>phenoxyethanol.

三种填塞材料在鼻内镜术后填塞中的临床效果分析

目的探讨三种不同的填塞材料在在鼻内镜术后填塞中的临床效果。方法选取60例鼻-鼻窦炎患者,术前采用视觉模拟量表(VAS)、Lund-kennedy鼻内镜检查评分系统,Lund-mackay鼻窦CT评分系统进行鼻窦病变严重程度评价,全部行鼻内镜鼻窦手术,术后根据情况分别置入凡士林胶皮指套(20例)、膨胀海棉(20例)、凡士林纱条(20例)进行填塞止血,48小时后取出填塞物。观察不同填塞材料在鼻内镜术后填塞应用中的止血效果,抽取鼻腔填塞物时难易程度、患者疼痛程度及鼻腔黏膜出血情况等,判断疗效。结果凡士林纱条胶皮指套填塞期与抽取时患者疼痛程度小,抽取时难度小、出血量少;膨胀海棉组患者填塞期出血量多;凡士林纱条组患者填塞期及抽取时疼痛程度高。结论自制凡士林纱条外套胶皮指套填塞物,表面光滑,无刺激性,具有弹性、黏膜之间黏附性小,抽取时较容易,鼻腔清洁度佳,达到满意临床效果,材料来源容易,制作工艺简单,价格低廉,对基层医院有临床推广价值。

Investigation of the mechanical performance of Al-coated DI steel sheets prepared by DC magnetron sputtering

Aluminum films coated on DI steel sheets were prepared by direct current （DC） magnetron sputtering.The influence of the deposition conditions and film thickness on the formability of coated steel sheets was studied.The results of the cupping test and drawing test show that the substrate temperature and thickness of Al films are the key factors that affect Al adhesion and formability of coated steel sheets.Adhesion became worse when the thickness of Al sheets was more than 2 μm.And formability was improved remarkably when the substrate temperature was increased to 200℃.

Effect of Process Parameters on Porosity in Aluminum Lost Foam Process

Porosity is a main defect in aluminum alloy castings, which is also thought to be severe in aluminum alloy castings produced by lost foam process due to the pyrolysis of the polystyrene foam pattern during pouring. Fundamental experiments were carried out to evaluate the effect of process parameters such as the melt treatment, the cooling rate and the density of expanded polystyrene （EPS） foam on porosity in A356.2 bar casting. The effect of melt treatment including degassing and refining was investigated. The effect of cooling rate was also evaluated by changing the mold packing material such as the silica sand, the zircon sand and the steel shots. Gas entrapment due to the turbulent metal flow during mold filling in conventional molding process results in porosity. Mold filling sequence in lost foam process is different from that in conventional molding process. The effect of molten metal flow was estimated by comparing the density of the casting by conventional sodium silicate molding with that by lost foam process. Density measurement was conducted to analyze the extent of porosity in the casting. Source of the porosity in lost foam process can be divided into two factors, i.e. turbulence in molten metal flow and entraining residue or gas from the pattern during pouring.

Preparative Optimization of Cellulose Microspheres Applied as Supports for High-Performance Liquid Chromatography

The aim of this work is optimizing the techniques to prepare pure cellulose microspheres, which are used as packing adsorbents for high-performance liquid chromatography. Thereupon, cellulose was dissolved in a pre-cooled NaOH/urea solution, from which various-size microspheres were prepared. The volume-average diameters were controlled approximately at 30 p,m, 8 ~tm and 4 pm grades when cyclohexane, liquid paraffin and pump oil were used as dispersants, respectively. The present investigations reveal that higher viscosity dispersant is suitable for the preparation of smaller-size microspheres, while larger size microspheres are prepared preferably using lower-viscosity dispersant. The chiral stationary phase derived from 8 μm grade microspheres can separate the enantiomers of efavirenz.

Preparation of porous hollow silica spheres via a layer-by- layer process and the chromatographic performance

Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene （PS） latex fabricated by dispersion polymerization as template. The formation of hollow SiO2 micro-spheres, structures and properties were observed in detail by zeta potential, SEM, TEM, FTIR, TGA and nitrogen sorption porosimetry. The results indicated that the hollow spheres were uniform with particle diameter of 1.6 μm and shell thickness of 150 nm. The surface area was 511 m2/g and the pore diameter was 8.36 nm. A new stationary phase for HPLC was obtained by using C18-derivatized hollow SiO2 micro-spheres as packing materials and the chromatographic properties were evaluated for the separation of some regular small molecules. The packed column showed low column pressure, high values of efficiency （up to about 43 000 plates/m） and appropriate asymmetry factors.