Design of a Prototype EHD Air Pump for Electronic Chip Cooling Applications

This paper presents the design,optimization and fabrication of an EHD air pump intended for high-power electronic chip cooling applications.Suitable high-voltage electrode configurations were selected and studied,in terms of the characteristics of the generated electric field,which play an important role in ionic wind flow.For this purpose,dedicated software is used to implement finite element analysis.Critical design parameters,such as the electric field intensity,wind velocity,current flow and power consumption are investigated.Two different laboratory prototypes are fabricated and their performances experimentally assessed.This procedure leads to the fabrication of a final prototype,which is then tested as a replacement of a typical fan for cooling a high power density electronic chip.To assist towards that end,an experimental thermal testing setup is designed and constructed to simulate the size of a personal computer’s CPU core of variable power.The parametric study leads to the fabrication of experimental single-stage EHD pumps,the optimal design of which is capable of delivering an air flow of 51 CFM with an operating voltage of 10.5 kV.Finally,the theoretical and experimental results are evaluated and potential applications are proposed.

Electronic moxibustion apparatus and traditional moxibustion in treating knee osteoarthritis:a randomized controlled trial

Objective:To observe the clinical efficacy of DZWJY-1 type electronic moxibustion apparatus and traditional moxibustion in treating knee osteoarthritis(KOA).Methods:A total of 76 eligible patients were randomized into an electronic moxibustion apparatus group and a traditional moxibustion group,with 38 cases in each group.The electronic moxibustion apparatus group was intervened by DZWJY-1 type electronic moxibustion apparatus,and the traditional moxibustion group received moxa stick moxibustion for treatment.Neixiyan(EX-LE 4),Dubi(ST 35),Xuehai(SP 10)and Liangqiu(ST 34)were selected for both groups and the treatment was conducted 3 times a week for a total of 12 times.The visual analog scale(VAS)and the Western Ontario and McMaster Universities osteoarthritis index(WOMAC)scores were observed before treatment and after 6 and 12 sessions of treatment,respectively.Results:There were 4 dropout cases in the traditional moxibustion group.Therefore,this trial had 72 valid cases,including 38 cases in the electronic moxibustion apparatus group and 34 cases in the traditional moxibustion group,the differences in the baseline data between the two groups were statistically insignificant(P>0.05).After 6 and 12 sessions of treatment,the VAS scores decreased significantly with the increase of treatment sessions in both groups(all P<0.01),and the betweengroup differences were statistically insignificant at the same time points(both P>0.05).The pain intensity was evaluated using the weighted value of VAS score.The markedly effective rate was 47.4%and the total effective rate was 89.5%in the electronic moxibustion apparatus group,versus 50.0%and 94.1%in the traditional moxibustion group,and the betweengroup differences were statistically insignificant(both P>0.05).After 6 and 12 sessions of treatment,the total score and the component scores including pain,stiffness and difficulty moving in the WOMAC decreased significantly with the increase of treatment sessions in both groups(all P<0.01),and the between-group differences were statistically insignificant(all P>0.05).Conclusion:Electronic moxibustion apparatus and traditional moxibustion both are effective in reducing joint pain and improving joint function in KOA patients,and they are equivalent comparing the clinical efficacy.

Antimicrobial effect of alexidine and chlorhexidine against Enterococcus faecalis infection

A previous study demonstrated that alexidine has greater affinity for the major virulence factors of bacteria than chlorhexidine.The aim of this study was to compare the antimicrobial activity of 1%alexidine with that of 2%chlorhexidine using Enterococcus faecalis-infected dentin blocks.Sixty bovine dentin blocks were prepared and randomly divided into six groups of 10 each.E.faecalis was inoculated on 60 dentin blocks using the Luppens apparatus for 24 h and then the dentin blocks were soaked in 2%chlorhexidine or 1%alexidine solutions for 5 and 10 min,respectively.Sterile saline was used as a control.The antimicrobial efficacy was assessed by counting the number of bacteria adhering to the dentin surface and observing the degradation of bacterial shape or membrane rupture under a scanning electron microscope.Significantly fewer bacteria were observed in the 2%chlorhexidine-or 1%alexidine-soaked groups than in the control group(P<0.05).However,there was no significant difference in the number of bacteria adhering to the dentinal surface between the two experimental groups or between the two soaking time groups(P>0.05).Ruptured or antiseptic-attached bacteria were more frequently observed in the 10-min-soaked chlorhexidine and alexidine groups than in the 5-min-soaked chlorhexidine and alexidine groups.In conclusion,10-min soaking with 1%alexidine or 2%chlorhexidine can be effective against E.faecalis infection.

Radiography of a K_α X-ray source generated through ultrahigh picosecond laser–nanostructure target interaction

Laser-driven ultrafast X-ray sources are widely used for diagnostic radiography. However, there is a large divergence of fast electrons when they are generated by an intense short-pulse laser interacting with a foil target. We design a nanowire array target to achieve a more compact point X-ray source. Fast electrons are confined and guided by the nanowire array structure in order to generate a Kα source with a small spot size. In our work, the smallest measured source size is comparable to the laser spot size, while the conversion efficiency can reach 2.4 ×10^-4.