Experimental investigation and COMSOL modeling for different geometrical configurations of extended surfaces

The current work presents and analyzes an experimental and three-dimensional COMSOL simulation to address and quantify the influence of different geometric cross-sectional shapes and types of materials (ie, brass and stainless steel) on the thermal performance of extended surfaces. Three cross-sectional shapes (ie, circular, square, and hexagonal) were examined under various base temperatures (ie, 40°C, 50°C, 60°C, and 70°C). Additionally, two types of fin materials, brass and stainless steel, were investigated to address the impact of thermal conductivity on the temperature distribution, local heat transfer coefficient, heat dissipation rate, efficiency, and effectiveness of extended surfaces. The experimental results showed a significant increase in the heat transfer coefficient and heat dissipation rates for hexagonal brass fins over other shapes and stainless steel fins. The simulation results were validated with the experimental temperature distributions for different geometries and materials under differing operating conditions (ie, different base temperatures, with and without an insulated fin tip). The validation and evaluation of the current COMSOL simulation indicated that the simulated results had high accuracy, with less than a 6% deviation, compared with the experimental data. The current validated COMSOL model can serve as a useful tool to facilitate the design and optimization of fins under various design and operating parameters.     

Synthesis of piperazinylalkyl ester prodrugs of ketorolac and their in vitro evaluation for transdermal delivery

Ketorolac, an NSAID, has low intrinsic permeation capacity through the skin. In this work, seven piperazinylalkyl ester prodrugs of ketorolac were synthesized to enhance its skin permeation. The chemical hydrolysis and the stability in human serum at 37 degrees C were investigated in buffer solutions (pH 5.0 and 7.4) and in 80% human serum (pH 7.4), respectively. The prodrugs were chemically more stable at pH 5.0 than at pH 7.4 with prodrug 8 being the most stable (t(1/2) = 119.75 h and 11.97 h at pH 5 and 7.4, respectively). The prodrugs' t(1/2) in human serum ranged from 0.79 to 3.92 min. The prodrugs' aqueous solubility was measured in buffer solution at pH 5.0 and 7.4 and Log P(app) was measured by partitioning between buffer solution (pH 5.0 and 7.4) and n-octanol. The prodrugs were more lipophilic than ketorolac at pH 7.4. Skin permeation of ketorolac and prodrug 8, the most stable chemically, through rat skin was studied at pH 5.0 and 7.4. Prodrug 8 enhanced permeation by 1.56- and 11.39-fold at pH 5 and 7.4, respectively. This is attributed to higher lipophilicity at pH 7.4 and higher aqueous solubility at pH 5 compared to ketorolac.     

Single column trapping/separation and chemiluminescence detection for on-site measurement of methyl mercaptan and dimethyl sulfide

A simple, automated method for the measurement of methyl mercaptan (CH3SH) and dimethyl sulfide (DMS) has been investigated. These two sulfur gases have strong and unpleasant odors. The collection and separation are performed in sequence with a single short column packed with silica gel powder. CH3SH and DMS are separated according to their desorption temperatures and introduced into a chemiluminescence cell in this order. These two gases emit strong chemiluminescence by reaction with ozone. The calibration curves obtained are linear, which is superior to flame photometric detection of these substances. The whole system, including a small cylinder for the carrier nitrogen, can be set in a portable box. The instrument is applicable to breath odor analysis, and automated measurement of room air can also be performed. In toilet air analysis, it was observed that levels of the sulfur gases increased after dark. With this instrument, sulfur gases at a ppbv level are successfully measured by a simple procedure without much interference.     

新型制馕坯机的工艺设计与制作

馕的加工制作一般由传统手工制馕工艺来实现,针对传统手工制馕工艺存在容易造成食品污染、速度慢、工作效率低、人力消耗大、满足不了大量加工制作馕品的需求等问题,研究一种采用电力启动的流水线式制馕坯装置显得尤为重要。在传统制馕工艺基础上,对流水线式自动制馕机进行工艺优化,其中对馕磨具和自动制馕机整体结构的详细设计,确定自动制馕机的工作方式。研究将改变传统的以人为主的手工制馕方式,实现机械化连续制馕坯。馕磨具的采用,减少了劳动量,提高了制馕速度和工作效率。连续制窝窝馕坯试验结果表明:当气泵空气压力为0.8 MPa,挤压时间为1.5 s,转送带转速为1.15 r/min,环境温度控制在25℃~35℃,发酵时间控制在30 min时,1 min内可以制出23.7个外形美观,大小一致,形状完整的馕坯。制馕坯机将对馕的标准化、商业化、产业化带来一定的便利。     

Authentication-enabled attribute-based access control for smart homes

International Journal of Information Security - Smart home technologies constantly bring significant convenience to our daily lives. Unfortunately, increased security risks accompany this...