Development of Miniature Compressed Air Storage System Using Solenoid Valves for Dynamic Pneumatic Actuator

Currently, there are many research that involved pneumatic device on vehicles. There are some applications using compressed air storage system to produce vehicle power. However, there are several constraints in producing compressed air for outdoor purpose, since most of the compressors are in large size which will cause limited working space. Also, most of the compressors are not portable and hand-carrying size. This paper objective is to investigate the parameters of a miniature air compressor during the reciprocation process and to analyze the compressed air pressure of piston type double-acting cylinder for the miniature air compressor. The piston rod is connected to connecting rod for mechanical movement, which the movement of the rod will convert kinetic energy to the piston and generate compressed air inside the storage tank. The system design allows the air into the tank to increase via reciprocating cylinder. Number of strokes produced is investigated. Subsequently, pressurized air inside the tank can be used to generate kinetic power to the pneumatic actuator. The force generated from the mechanism is then measured. Synchronization of 5/3 Ways Directional Control Valves (DCV) is the key of the system to ensure the flow of compressed air wellkept in the storage tank. The pressurized air inside the tank transfers the power into kinetic movement via reciprocating piston and able to generate 200kPa of compressed air

Prediction of maximum spreading time of water droplet during impact onto hot surface beyond the Leidenfrost temperature

When a water droplet impacts on a heated surface in the film boiling regime, it will spread, recede, and finally bounce off from the heated surface. These unique liquid-solid interactions only occur at high surface temperatures. Our main objective in this research is to measure the maximum spreading and residence time of the droplet and the findings were compared to theory. We focused our study in the film boiling regime. Brass material was selected as the test surface and was polished until it became a mirror polished surface. The temperature range for this experimental work was between 100 ◦C up to 420 ◦C. Degassed and distilled water was used as the test liquid. The high speed video camera recorded the images at the rate of 10,000 frames per second (fps). As a result, it was found that the experimental value of maximum spreading and esidence time agreed closely with the theoretical calculation. A new empirical formula that can be used to predict the maximum spreading time in the film boiling regime is also proposed

Mutations in the Beta Propeller WDR72 Cause Autosomal-Recessive Hypomaturation Amelogenesis Imperfecta

Healthy dental enamel is the hardest and most highly mineralized human tissue. Though acellular, nonvital, and without capacity for turnover or repair, it can nevertheless last a lifetime. Amelogenesis imperfecta (AI) is a collective term for failure of normal enamel development, covering diverse clinical phenotypes that typically show Mendelian inheritance patterns. One subset, known as hypomaturation AI, is characterised by near-normal volumes of organic enamel matrix but with weak, creamy-brown opaque enamel that fails prematurely after tooth eruption. Mutations in genes critical to enamel matrix formation have been documented, but current understanding of other key events in enamel biomineralization is limited. We investigated autosomal-recessive hypomaturation AI in a consanguineous Pakistani family. A whole-genome SNP autozygosity screen identified a locus on chromosome 15q21.3. Sequencing candidate genes revealed a point mutation in the poorly characterized WDR72 gene. Screening of WDR72 in a panel of nine additional hypomaturation AI families revealed the same mutation in a second, apparently unrelated, Pakistani family and two further nonsense mutations in Omani families. Immunohistochemistry confirmed intracellular localization in maturation-stage ameloblasts. WDR72 function is unknown, but as a putative β propeller is expected to be a scaffold for protein-protein interactions. The nearest homolog, WDR7, is involved in vesicle mobilization and Ca2+-dependent exocytosis at synapses. Vesicle trafficking is important in maturation-stage ameloblasts with respect to secretion into immature enamel and removal of cleaved enamel matrix proteins via endocytosis. This raises the intriguing possibility that WDR72 is critical to ameloblast vesicle turnover during enamel maturation

Experimental investigation of critical heat flux during impact of a droplet onto hot horizontal surface

The purpose of this research is to investigate the Critical Heat Flux (CHF) and its relationship with thermal inertia during impact of a droplet on hot horizontal surface. In the study, three (3) different types of material were used which were Aluminum, Brass and Stainless Steel (304). The materials dimension were 50.0 mm in diameter and 30.0 mm in height. The materials were polished until they became a mirror polished surface. Ethanol was used as the test liquid. The droplet diameter was approximately 3.528 mm. The impact height was approximately 65.0 mm corresponding to impact velocity of 1.129 m/s. The evaporation lifetime was measured in seconds by using a digital stopwatch. As a result, it was observed that the CHF occurred at the surface temperatures of 105, 120 and 160 °C for aluminum, brass and stainless steel, respectively. It was also observed that all CHF data showed an evaporation lifetime below 1 sec order which is similar with other literatures

Heterologous Expression Of Xylanase Gene From Klebsiella Pneumoniae In E. Coli Bl21 (De3) For Potential Use In Green Technology

A xylanolytic bacterium was isolated from sago plantation humus. Isolation and characterization of xylanase DNA sequence showed a total length of 642 bp. The full length xylanase gene was cloned in pSTAG vector and expressed in E. coli BL21 (DE3). In silico characterization determines the recombinant xylanase has a molecular weight of 23.9 kDa. The activity of crude recombinant xylanase was 2.015 U/mL, which was higher than the crude native xylanase activity that was only 0.642 U/mL at maximum. Staining of the birchwood xylan agar plate with Congo red showed a clearing zone around E. coli BL21 (DE3) that has positive recombinant xylanase even without the addition of IPTG, implying leaky expression had occurred. Further analysis showed the existence of two forms of the xylanase. These xylanases were enzymes with the size of 25kDa that accumulates in the cell, and the other as a 20kDa mature extracellular xylanase

Characterisation of Klebsiella pneumoniae Xylanase and Increment of Its Activity in Heterologous Expression System

A xylanase DNA sequence with a total length of 642 bp was previously isolated from a xylanolytic Klebsiella pneumoniae. Xylanase gene primers were designed with the addition of BamH1 and EcoR1 restriction enzyme sites in order get a full xylanase gene that is in-frame with pSTAG expression vector. The isolated xylanase gene was amplified using the designed primers through PCR, then cloned and expressed in E. coli BL21 (DE3). In-silico characterization showed that the recombinant xylanase has a molecular weight of 23.9 kDa and a pI of 9.32. The signal peptide cleavage site for the recombinant xylanase was predicted to be between residues 61 and 62. The activity of the crude recombinant xylanase was 2.015 U/mL, which was higher than the crude native xylanase activity, with maximum at 0.642 U/mL. Staining of the birchwood xylan agar plate with Congo red showed a clearing zone around E. coli BL21 (DE3) colonies with recombinant pSTAG plasmid even without being induced with IPTG. This implied leaky expression of the E. coli BL21 (DE3) secretion system, which recognized the signal sequence of the recombinant xylanase, and proceeded to cleave and secreted out the mature protein into the culture medium. MALDI-TOF analysis of a 20 kDa protein present in the culture medium confirmed that the recombinant xylanase had been secreted into the culture medium

Critical heat flux and Leidenfrost temperature on Electrical Discharge Machining (EDM) - constructed hemispherical surface

This paper reports a Leidenfrost temperature on hemispherical surface constructed by Electrical discharge machining or known as EDM. We focus our study on the droplet evaporation lifetime to investigate and identify the Leidenfrost temperature. Three (3) different types of materials were selected i. e such as Brass (Br), Aluminum (Al) and Copper (Cu). Meanwhile, ethanol liquid has been chosen as the test liquid. Ethanol liquid was elected due to its low boiling point of approximately 78 ◦C. The droplet impact velocity and droplet diameter was approximately 1.129 m/s and 3.476 mm, respectively. As a result, we finally succeeded in determining the Leidenfrost temperature for all materials mentioned above. On top of that, all the Leidenfrost temperature results, TL were close to the superheat limit temperature of ethanol liquid, TSL which is about 197.8 ◦C

Investigation on water droplet receding height impacting onto heated carbon surface

This study investigates the receding water droplet height upon impact on a high temperature carbon surface in the film boiling regime. A 30.0-mm-diameter carbon disc with a height of 8.0 mm was used as the test surface due to its relativity low thermal conductivity compared to the more commonly studied alloy materials. For the water droplet, the diameter and temperature was constant at approximately 4.0 mm and 16.0 °C, respectively. The water temperature was maintained at the required temperature by circulating tap water into the droplet dispenser system. Meanwhile, the impact height was set at 65.0 mm which corresponds to a theoretical impact velocity of 1.129 m/s. A high speed video camera capable of capturing images at 10,000 fps was used to capture the impacting process. From the results obtained, it was found that the experimentally measured residence time was in good agreement with that calculated based on theory. Another important finding from the study was that the surface temperature had no significant effect to the changes in the water droplet height upon impact on the hot carbon surface

Receding height of water droplet in the film boiling regime

The purpose of this research was to study and investigate the receding height of water droplet after it impinged on hot aluminum surface. On top of that, we also investigated the relationship between this receding phenomenon and residence time of water droplet. Degassed and distilled water was used as a droplet. The droplet diameter was maintained at 4.0 mm and the impact height was set to be around 65.0 mm corresponding to impact velocity of 1.129 m/s. The liquid temperature was kept around 16 °C corresponding to liquid subcooling of ∆Tsub = 84 K. The material selected in this experiment was aluminum surface. The surface had been polished until it became a mirror polished surface. The dimensions of the material surface were 30.0 mm in diameter and 8.0 mm in height. The phenomena were recorded at 10,000 frames per second using a high speed video camera. As a result, it was observed that the receding height during film boiling regime was almost similar to each other even the surface temperature was different. Furthermore, the residence time during the experiment was also close to the theoretical calculation