Effect of Shell Temperature on Thermal Resistance and Junction Temperature for Power Diode

Accurate measurement of junction temperature can avoid thermal failure of diode. During aging test, junction temperature should be indirectly calculated by testing its thermal resistance. In this paper, junction-to-case thermal resistance (Rthjc) of XX diode is tested by T3ster based on transient dual interface method. Its Rthjc is about 1.23K/W at 25°C and contains PN junction thermal resistance, metal shell thermal resistance and Sn-based solder thermal resistance, respectively. These three types of thermal resistance decrease in order. Effect of shell temperature on junction temperature and Rthjc is then discussed. As shell temperature increases, temperature variation of PN junction before and after heating and corresponding thermal resistance Rthjc both increase.

Effects of rice husk ash on itself activity and concrete behavior at different preparation temperatures

This paper aims to investigate the effects of rice husk ash (RHA) on itself activity and its concrete performance at different preparation temperatures for which three temperatures of 650 °C, 800 °C, and 900 °C were considered. To find a reasonable particle size, the effect of the particle size of the RHA on the workability of concrete at various grinding times was studied. A series of experiments were carried out to study the characteristics of the RHA, including X-ray fluorescence, XRD, ESEM, and an activity test. The carbonation resistance and frost resistance of concrete incorporating RHA were also investigated, where 10 and 30 wt.-% of cement was considered. The results show that the surface area of the RHA first increases and then decreases with grinding time. When the RHA is ground for 30 min, its surface area is largest and the workability of its mixture is also best. The burning temperature has little effect on the amount of SiO2. Although the structure and activity of SiO2 in RHA change at different burning temperatures, the performance of concrete incorporating RHA is higher than that of control concrete without RHA. With the same content of RHA, both carbonization resistance and frost resistance decrease with an increasing burning temperature of RHA. At the same burning temperature, both carbonization resistance and frost resistance increase with an increasing amount of RHA. Among all types of mixtures, the mixture incorporating 30 % RHA burned at 650 °C (i. e., RHA650) yields the best performance.

Investigation on Heat Transfer Enhancement in Microchannel Using Al2O3/Water Nanofluids

Nowadays, reducing heat generation in electronic devices while using microchannel cooling is used to solve this problem. Because the trend is globally marching toward the compact size, the component’s dimensions get smaller, but the warmth involved within the component increases. Studies of heat transfer rate are conducted to determine the effect of a fully heated microchannel conductor’s heat transfer performance. Experiments are performed using nanofluid Al2O3/water through a concentration percentage of 0.1% and 0.25% and deionized water through a microchannel conductor with 25 rectangular microchannel numbers with a dimension of ( 0.42 × 0.42 × 100 ) mm3. This present work deals with the effect of nanofluids and their concentration percentages. Finally, it concluded that better heat transfer performance was seen in nanofluids compared to deionized water. The reason is the high viscosity of nanofluid Al2O3/water due to these nanoparticles is deposited on the wall surface of the microchannel and outcomes trendy improvement in the heat transfer. Finally, a high concentration percentage of nanofluids revealed a practical improvement in the transfer of microchannel. As a result, 0.25% of the concentration percentage achieved a satisfactory result compared to the remaining fluids and almost 32.5% and 26% of thermal resistance decrease.

Longitudinal size effects on electrical and actuation behaviors of ionic polymer-metal composite

The structural characteristics of ionic polymer-metal composite (IPMC) were analyzed, and the effects of IPMC length ranging from 1 to 5 cm (with a width of 0.5 cm) were evaluated in terms of electrical parameters and actuation behavior. It has been concluded that the electrical parameters of IPMC materials (including capacitance, electrode resistance in thickness-direction, and internal resistance) decrease, and the bending strain of the setpoint increases as the length increases. The simulation of the current response of IPMC to 2 V DC voltage shows that the error between simulated peak current using 1 cm-IPMC parameters and the measured value is 8.23 times higher than that of 5 cm-IPMC. The strain of the set point on 5 cm-IPMC sample is 5.65 times bigger than that of the 1 cm-IPMC sample.

Karakteristik Pasien dengan Nodul Tiroid di Rumah Sakit Al-Ihsan Bandung

Nodul tiroid merupakan kasus yang dapat disebabkan oleh berbagai jenis gangguan kelenjar tiroid dan masih sering ditemukan. Sekitar 90% nodul tiroid bersifat jinak dan 10% bersifat ganas. Di Indonesia data statistik mengenai nodul tiroid masih sangat kurang. Penelitian ini bertujuan mengetahui karakteristik pasien dengan nodul tiroid. Penelitian ini menggunakan metode deskriptif observasional dengan pendekatan potong lintang. Teknik pengambilan sampel dalam penelitian ini adalah total sampling. Data didapatkan melalui rekam medis tahun 2018–2019 di Rumah Sakit Al-Ihsan Bandung dan didapatkan 72 rekam medis yang memenuhi kriteria inklusi yang dilakukan periode tahun 2018–2019. Hasil penelitian menunjukkan frekuensi tertinggi berdasar atas usia terdapat kelompok usia 40 - 49 tahun 32%. Frekuensi tertinggi berdasar atas jenis kelamin terdapat pada pasien perempuan 90%. Frekuensi tertinggi berdasar atas ukuran nodul tiroid terdapat pada kelompok >4 cm 72%. Frekuensi tertinggi berdasar atas gambaran histopatologi berupa adenomatoid goiter 74%. Simpulan penelitian ini menunjukkan frekuensi tertinggi terjadi nodul tiroid terdapat pada usia 40-49 tahun, perempuan, ukuran nodul tiroid >4 cm dan jenis adenomatoid goiter. Hal ini terjadi karena imunitas dan daya tahan tubuh seseorang menjadi menurun seiring dengan usia yang bertambah. Pada perempuan risiko penyakit nodul tiroid dapat meningkat dengan penggunaan hormon estrogen pada kontrasepsi oral, pada kehamilan, serta perubahan siklus menstruasi. Characteristics of Patients with Thyroid Nodule at the Al-Ihsan Hospital BandungThyroid nodule is a disease that can be caused by various disorders. About 90% of thyroid nodules are benign and 10% are malignant. In Indonesian, statistical data for thyroid nodules are still limit. The porpose of this study was to collect the characteristics of patients with thyroid nodules at the Al-Ihsan Hospital Bandung. This study used a observational descriptive method using total sampling technique. Data were obtained through medical records for January 2018–December 2019 at Al-Ihsan Hospital and obtained 72 medical records that met the inclusion criteria the study was held during January 2018–December 2019. The results showed that the highest frequency based on age was found in the 40 - 49 years age group at 32%. The highest frequency based on gender was found in female patients by 90%. The highest frequency based on the size of thyroid nodules was found in the group >4 cm at 72%. The highest frequency based on histopathological features was found in adenomatoid goiter by 74%. The conclusions in this study indicate that the highest frequency of thyroid nodules occurs at the age of 40 - 49 years, women, thyroid nodule size >4 cm and adenomatoid goiter type. This happens because a person's immunity and body resistance decrease with age. In women, the risk of thyroid nodule disease can increase with the use of the hormone estrogen in oral contraceptives, in pregnancy and changes in the menstrual cycle.

Probiotics in Fish Nutrition—Long-Standing Household Remedy or Native Nutraceuticals?

Over the last decades, aquaculture production increased rapidly. The future development of the industry highly relies on the sustainable utilization of natural resources. The need for improving disease resistance, growth performance, food conversion, and product safety for human consumption has stimulated the application of probiotics in aquaculture. Probiotics increase growth and feed conversion, improve health status, raise disease resistance, decrease stress susceptibility, and improve general vigor. Currently, most probiotics still originate from terrestrial sources rather than fish. However, host-associated (autochthonous) probiotics are likely more persistent in the gastrointestinal tract of fish and may, therefore, exhibit longer-lasting effects on the host. Probiotic candidates are commonly screened in in vitro assays, but the transfer to in vivo assessment is often problematic. In conclusion, modulation of the host-associated microbiome by the use of complex probiotics is promising, but a solid understanding of the interactions involved is only in its infancy and requires further research. Probiotics could be used to explore novel ingredients such as chitin-rich insect meal, which cannot be digested by the fish host alone. Most importantly, probiotics offer the opportunity to improve stress and disease resistance, which is among the most pressing problems in aquaculture.

A ribosomal protein variant that confers macrolide resistance differentially regulates acid resistance, catabolism, and biofilm formation related genes in Escherichia coli

ABSTRACTMutational changes in bacterial ribosomes that confer antibiotic resistance decrease cell fitness. Determining the genetic factors that interconnect antibiotic resistance and cell fitness is critical in the fight against bacterial infections. Here, we describe gene expression and phenotypic changes presented in Escherichia coli cells carrying an uL22(K90D) mutant ribosomal protein, which showed growth defects and resistance to macrolide antibiotics. Ribosome profiling analyses revealed reduced expression of operons involved in catabolism, electron transportation, indole production, and lysine-decarboxylase acid resistance. In general, ribosome occupancy was increased at rare codons while translation initiation of proximal genes in several of the affected operons was substantially reduced. Decline of the activity of these genes was accompanied by increased expression of macrolide multidrug efflux pumps, the glutamate-decarboxylase regulon, and the autoinducer-2 metabolic regulon. In concordance with these changes, uL22(K90D) mutant cells grew better in acidic conditions and generated more biofilm in static cultures than their parental strain. Our work provides new insights on how mutations in ribosomal proteins induce the acquisition of macrolide and pH resistance, and increase the ability to generate biofilms.

Nano- and Micro-Modification of Building Reinforcing Bars of Various Types

Fiber-reinforced plastic (FRP) rebar has drawbacks that can limit its scope, such as poor heat resistance, decrease its strength over time, and under the influence of substances with an alkaline medium, as well as the drawback of a low modulus of elasticity and deformation. Thus, the aim of the article is the nano- and micro-modification of building reinforcing bars using FRP rebars made of basalt fibers, which were impregnated with a thermosetting polymer binder with micro- or nanoparticles. The research discusses the major results of the developed composite reinforcement with the addition of micro- and nanosized particles. The microstructure of FRP has been studied using scanning electron microscopy. It was revealed that dispersion-strengthened polymer composites with the inclusion of microsilica (SiO2) and nanosized aluminum oxide (Al2O3) particles have a much higher modulus of elasticity and strength when compared with the original polymer materials. In the course of the experiment, we also studied the retained plastic properties that are characterized by the absence of fragility. However, it was found that the high strength of materials was attained with a particle size of 10–500 nm, evenly distributed in the matrix, with an average distance between particles of 100–500 nm. It was also exhibited that composite reinforcement had improved the adhesion characteristics in comparison with both steel reinforcement (1.5–2 times, depending on the diameter), and with traditional unmodified FRP rebar (about 1.5 times). Thus, the use of micro-/nanosized powders increased the limit of the possible temperature range for the use and application of polymeric materials by almost two times, up to 286–320 °C, which will undoubtedly expand the range of the technological applications of products made of these materials.

Experimental Study on Motion Behavior and Longitudinal Stability Assessment of a Trimaran Planing Hull Model in Calm Water

In this study, a high-speed planing trimaran hull form is designed, and the effects of different displacements and gravity longitudinal layouts on the performance of the trimaran planing hull in calm water are experimentally investigated in the towing tank of the China Special Vehicle Research Institute. Based on previous work, an innovative inner tunnel appendage hydroflap is mounted in the inner aft tunnel, located 1/8 L from the transom in the longitudinal direction with attack angles of 0° and 4°, respectively. Furthermore, a regular stern flap is mounted on the transom close to the chine. The towing test results show that, as the gravity center moves forward, the high-speed region resistance of the planing trimaran increases and the longitudinal stability is also strengthened. Further, the total resistance of the planing trimaran with a heavier displacement is larger while the average mass resistance declines; i.e., the resistance efficiency is improved. The results also indicate that the inner tunnel hydroflap and stern flap enhance the aft hull hydrodynamic lift and tunnel aerodynamic lift. As a result, mounting aft hull lift enhancement appendages can affect the bottom and inner tunnel pressure distribution and then cause a slight resistance decrease in the low-speed region. The value relationship of resistance between groups of appendages for the attached hull and bare hull is reversed at a speed of about Froude number 3.0. Although the aft hull lift enhancement appendages result in a higher resistance cost in the high-speed region, the longitudinal stability is effectively promoted and the occurrence speed of porpoising results in a delay of 1 to 2 m/s.

A Study on the Effect of Bond Wires Lift-Off on IGBT Thermal Resistance Measurement

Bond wire lift-off will cause an increase of remaining wires’ power dissipation, which usually is ignored for healthy modules. However, only partial wires’ power dissipation transfers through thermal path from junction to case, which will lead to overestimate the whole power dissipation from collector to emitter pole and underestimate the calculated thermal resistance using the proportion of temperature difference to power dissipation. A FEM model is established to show the change of heat flow after bond wires were removed, the temperature of bond wires increases, and the measured thermal resistance decrease after bond wires lift-off. It is validated by experimental results using open package Insulated Gate Bipolar Transistor (IGBT) modules under different current conditions. This conclusion might be helpful to indicate the bond wires lift-off and solder fatigue by comparing the change of measured thermal resistance. Using the Kelvin setup to measure thermal resistance will cause misjudgment of failure mode due to the ignoring of wires’ power dissipation. This paper proposed that the lift-off of bond wires will lead to underestimating the thermal resistance measurement, which will overestimate the lifetime of IGBT module and misjudge its state of health.