Performance of a multi-stack microchannel heat sink

The usage of a very large scale integrated circuits generate high heat fluxes and require an effective cooling system. A microchannel heat sink (MCHS) is one of the reliable cooling systems that had been applied. In terms of performance, a MCHS can be appraised by obtaining low total thermal resistance and pumping power. However, as the total thermal resistance decreases, the pumping power will increase. A few studies have been focused on the minimization of the thermal resistance and pumping power of a multi-stack MCHS. Optimization of two objective functions which are the total thermal resistance and pumping power has been done by using genetic algorithm. It is demonstrated that both objective functions can be minimized by optimizing two design variables which are the channel aspect ratio, α, and wall width ratio,β. It was found that the usage of a stacked configuration for the MCHS is able to reduce the total thermal resistance. From the optimization, it was found that the optimum number of stacks that can be implemented is three. With the three-stack configuration, the total thermal resistance found is 0.1180 K/W which is 21.8% less compared to the single-stack MCHS. However, the pumping power needed for the three-stack MCHS is increased by 0.17 % compared to single-stack which is 0.7535 W

Automated characterization of single-photon avalanche photodiode

We report an automated characterization of a single-photon detector based on commercial silicon avalanche photodiode (PerkinElmer C30902SH). The photodiode is characterized by I-V curves at different illumination levels (darkness, 10 pW and 10 uW), dark count rate and photon detection efficiency at different bias voltages. The automated characterization routine is implemented in C++ running on a Linux computer.Comment: Have permission to post journal-formatted version on arXi

Uji Aktivitas Hepatoprotektif Teh Hijau Kombucha Pada Tikus Putih Yang Diinduksi Parasetamol

Paracetamol is an analgesic-antipyretic drug that has hepatotoxic effect when taken in high doses. Paracetamol toxicity is due to the formation of toxic metabolites when a part of it is metabolized by cytochrome P450. This study was designed to evaluate the hepatoprotective activity of green kombucha tea (GKT) in wistar albino rats. Acute liver injury was induced by paracetamol (750mg/kg, b.w). GKT at the dose of 0.5, 1.0, and 1.5 ml, p.o was administered for 7 days. The biochemical parameters of liver such as serum glutamate oxaloacetate transaminase (SGOT), glutamate pyruvate transaminase (SGPT) levels were measured using spectrophotometer. Finally, the liver weight (Wt/100g b.w) of rats were recorded. GKT in all doses prevented the increase of liver weight significantly (p<0.05) when compared with paracetamol treated rats. The dose 1.0 ml of GKT was found to be the most effective than the other dose (0.5 and 1.5 ml). GKT produced hepatoprotective effect significantly (p<0.05) by decreasing the activity of serum enzyme such us SGOT and SGPT. The 1.0 ml dose of GKT also found to be the most effective dose to decrease the levels of SGOT and SGPT. It is concluded that the Green kombucha tea possesses good hepatoprotective activity

Training needs assessment in Malaysia: Exercise held at Kuala Lampur and Kota Bharu from 13th October 1989

Training / Irrigation / Evaluation / Malaysia

Perancangan Alat Pemeras Kelapa Parut Menjadi Santan Dengan Cara Pengepresan Manual Yang Ergonomis

Sering ditemukan mesin atau alat pemeras kelapa parut dipasar tradisional dikota Medan. Mesin atau alat tersebut dijual dengan harga yang relatif mahal, kurang ergonomis dan dengan kapasitas input yang kecil. Tujuan dari penelitian ini adalah pembuatan rancangan mesin pemeras kelapa parut yang ergonomis, input besar dan murah. Tahapan yang digunakan adalah mendeteksi keluhan musculoskeletal yang diakibatkan oleh pemakaian alat yang sudah ada. Dengan menggunakan Standard Nordic Questionnairre (SNQ) dengan cara menyebarkan kuisioner. Hasil penilaian kuisioner digunakan sebagai dasar untuk merubah dimensi alat agar sesuai dengan anthropometri operator yang akan menggunakan. Setelah rancangan dimensi alat sesuai dengan konsep ergonomi maka dilakukan penyebaran kuisioner terbuka dan kuisioner tertutup untuk pembuatan Quality Function Deployment (QFD). Kemudian diukur waktu siklus untuk menentukan waktu pemerasan alat pemeras kelapa parut. Berdasarkan perancangan alat kelapa parut yang baru maka diusulkan metode kerja baru yang telah distandarkan berupa standard operation procedure (SOP) alat Pemeras kelapa parut. Dari hasil pengolahan data dan analisis pemecahan masalah dapat diambil kesimpulan bahwa perancangan alat pemeras kelapa parut usulan dapat meminimalkan keluhan Muscoluskeletal pada operator. Hasil santan alat pemeras kelapa parut usulan memberikan hasil lebih banyak 20% dari alat yg lama, alat kelapa parut usulan lebih murah harganya dibandingkan dengan alat pemeras kelapa parut yang ada dipasaran dan waktu siklus dari alat pemeras kelapa parut usulan lebih cepat 5% dibandingkan dengan alat pemeras kelapa parut yang lama. Dengan syarat harus menggunakan SOP yang sudah dibua

Hubungan Belajar Mandiri dengan Prestasi Belajar Pai di Mtsn 1 Konawe Selatan

Tujuan penelitian kausal ini adalah untuk mendapatkan informasi mengenai pengaruh gaya kepemimpinan, kompetensi profesional, kompetensi pedagogik, dan iklim kerja terhadap prestasi kerja guru bahasa inggris SMP Kota Kendari. Penelitian dilakukan dengan menggunakan metode survei dan pengujian hipotesis menggunakan analisis jalur. Sampel penelitian guru bahasa Inggris SMP sebanyak 80 orang. Hasil penelitian adalah sebagai berikut (1) Ada pengaruh positif langsung gaya kepemimpinan terhadap prestasi kerja; (2) Ada pengaruh positif langsung kompetensi profesional terhadap prestasi kerja; (3) Tidak ada pengaruh positif langsung kompetensi pedagogik terhadap prestasi kerja; (4) Ada dampak positif langsung iklim kerja terhadap prestasi kerja; (5) Ada pengaruh positif langsung gaya kepemimpinan terhadap iklim kerja; (6) Ada pengaruh positif langsung kompetensi profesional terhadap iklim kerja; (7) Ada pengaruh langsung langsung kompetensi pedagogik terhadap iklim kerja. Berdasarkan temuan tersebut, dapat disimpulkan bahwa prestasi kerja guru bahasa Inggris SMP di Kota Kendari dapat ditingkatkan dengan meningkatkan gaya kepemimpinan, kompetensi profesional, kompetensi pedagogik dan iklim kerja

Isolation of bioflocculant-producing bacteria from Penaeus vannamei ponds for the production of extracellular polymeric substances

Bioflocculants are essential polymers with their flocculating activity depending on the characteristics of the secreted flocculants by bioflocculant-producing bacteria. However, the characteristics of bioflocculant produced by microorganisms were not investigated profoundly. In order to better understand these characteristics, determination of extracellular polymeric substances (EPS) from bioflocculant-producing bacteria were characterized in terms of protein concentrations. A total of 51 bioflocculant-producing bacteria isolates were screened from Pacific whiteleg shrimp, Penaeus vannamei culture ponds in Setiu, Terengganu, Malaysia. Screening of bioflocculant-producing bacteria were conducted through morphological approaches followed by protein extraction using Lowry assay method. The identified bioflocculant-producing bacteria includes Corynebacterium sp., Klebsiella sp., Lactobacillus sp., Staphylococcus sp., Bacillus sp., Streptococcus sp., Vibrio spp., Neisseria sp., Serratia sp. and Yersinia sp., with the highest protein concentration of 829 mg mL-1 were attained by Staphylococcus sp. The various amounts of EPS concentration produced by different species of bacteria were dependent on their specific population growth and growth rate. Therefore, the establishment of bioflocculant-producing bacteria isolated from biofloc which showed high tendency for EPS production were performed successfully

Visual Thinking Process and Emotions Through Expressive Art

Background: Drawing has a therapeutic function in the lives of people with special needs.These people need additional support for communication and learning.Researchers believed that drawing is an effective way for these people to show their self-esteem, emotions, social competence, and other hidden personalities. Art therapy teaches knowledge of visual art (drawing and painting). It is also known as expressive art because it assists in dealing with some emotions that are difficult for verbal communication. Furthermore, art therapy is beneficial for fine motor skill development. The aim of this study was to explore the use of expressive art in a group of autistic people. Subjects and Method: This was a qualitative study. A series of art therapy workshop were conducted in University of Malaya in collaboration with Malaysian Rehabilitation Council, and Maybank Foundation. A number of 18 people aged 8-17 years old with autism from Malaysian Rehabilitation Council were invited to University of Malaya for the art therapy workshop. They consisted of Malays, Chinese, and Indians. These peoplehad some level of communication problems. Art therapy workshop was conducted twice a month for 6 month with each session lasted for 4 hours. Art template, art materials, and a list of activities were given to each participant. Before the session, the participants informed the researchers verbally the scope of art that they would be drawing. The researchers observed the thinking process and emotions of the participants through the art activities. Results: Some of the art work was not related to what they have mentioned earlier. We found that art demonstrated their thought process. Drawing was more accurate in visualizing their thinking process rather than verbal communication. Besides, we detected a range of emotions illustrated from their final art work. Some of the emotions were psychological distress, happiness, and sadness. Conclusion: Expressive artis useful for visualizing thinking process of autistic people. Keywords: art therapy, autistic, visual thinking, emotions, expressive ar