Power losses of switches and inductors are consistent challenges that hinder the development of high-frequency power supply in package (PSiP). This paper investigates the roadmap for power loss optimizations of switches and inductors in high-frequency PSiPs. Firstly, a size and parallel quantity design method to reduce power loss in an integrated Si LDMOSFET is provided with comprehensive consideration of switching frequency and power levels. Secondly, quality factors of different air-core inductors are analyzed with consideration of geometric parameters and skin effect, which provides the winding structure optimization to reduce power losses. The power losses of the integrated Si LDMOSFET and air-core inductors are both reduced to less than 10% of the output power at 1~100 MHz switching frequency and 0.1~10 W power level. Finally, based on the above optimizations, power losses of switches and inductors are calculated with switching frequency and power level. Combining the calculated results, this paper predicts the efficiency boundaries of PSiPs. Upon efficiency normalization with consideration of input and output voltage levels, all the predictions are consistent with the published literature. The efficiency predication error is 1~15% at 1~100 MHz switching frequency and 0.1~10 W power level. The above power loss optimizations improve the efficiency, which provides potential roadmaps for achieving high-frequency PSiPs.
Lactobacillus plantarum strain ST-III, a probiotic strain with several functions, was isolated from kimchi. Here we report the complete genome sequence of ST-III and compared it with two published L. plantarum genomes.
Kefir is an acidic, mildly alcoholic dairy beverage produced by the fermentation of milk with a grain-like starter culture. These grains usually contain a relatively stable and specific balance of microbes that exist in a complex symbiotic relationship. Kefir grains can be considered a probiotic source as it presents anti-bacterial, anti-mycotic, anti-neoplasic and immunomodulatory properties. The microorganisms in Kefir grains are currently identified by traditional methods such as growth on selective media, morphological and biochemical characteristics. However, the microorganisms that isolate by these methods can not revert to Kefir grains which indicate that there are some other bacteria that are not isolate from it. In this study, PCR-based Denaturing gradient gel electrophoresis(DGGE) and sequence analysis of 16S ribosomal RNA gene (16S rDNA) clone libraries was used for the rapid and accurate identification of microorganisms from Kefir grains. The PCR primers were designed from conserved nucleotide sequences on region V3 of 16S rDNA with GC rich clamp at the 5'-end. PCR was performed using the primers and genomic DNAs of Kefir grains bacteria. The generated region V3 of 16S rDNA fragments were separated by denaturing gel, and the dominant 16S rDNA bands were cloned, sequenced and subjected to an online similarity search. Research has shown that regions V3 of 16S rDNAs have eight evident bands on the DGGE gel. The sequence analysis of these eight bands has indicated that they belong to different four genera, among them three sequences are similar to Sphingobacterium sp. whose similarities with database sequences are over 98%, three sequences are similar to Lactobacillus sp. whose similarities with database sequences are over 96%, the other two sequence are similar to Enterobacter sp., and Acinetobacter sp. whose similarities with database sequences are over 99% respectively. Although the DGGE method may have a lower sensitivity than the ordinary PCR methods, because when universal bacterial PCR primers are used, only the dominant microbiota of an ecosystem will be visualized on a DGGE gel, producing complex banding patterns. However, it could visualize the bacterial qualitative compositions and reveal the major species of the Kefir grains. Among them Sphingobacterium can be found in Kefir grains as the predominant flora which is reported for the first time. PCR-based DGGE and sequence analysis of 16S rDNA proved to be a valuable culture-independent approach for the rapid and specific identification of the microbial species present in microecosystem and probiotic products.
The antagonistic activities of Lactobacillus plantarum Guo against the adhesion of Escherichia coli and Salmonella enteritis to Caco-2 cells were compared with the well-investigated Lactobacillus rhamnosus GG with a fluorescent labelling method. The protective effects of the Guo on Caco-2 cells were studied by the analysis of cell membrane permeability. The results of the antagonistic ability of Guo showed significant effects of strain, dose and strain-dose interaction (P<0.05) for E. coli and S. enteritis. The highest inhibition rate (56.97%) was obtained in the exclusion assay of ST-III (1.0×10 9 /mL) against E. coli, indicating that a specific antagonistic effect may be involved between L. plantarum and E. coli. Among the three mechanisms for an antagonistic effect (exclusion, competition and displacement), the most effective way for E. coli inhibition through ST-III was exclusion whereas competition was the most effective mechanism for LGG. In the membrane permeability assay, co-incubation of ST-III with pathogens and Caco-2 cells after 3 h showed dramatic decrease of Caco-2 cells injury. Guo could protect Caco-2 cells by competing for specific receptors or though steric hindrance against pathogens. In conclusion, ST-III could successfully inhibit the adhesion of enteric pathogens and protect mammalian epithelial cells from being damaged.
It takes long time for cheese ripening,which lead to the increase of the manufacture cost.Accelerated ripening of cheese is one of the effective ways to reduce it.Approaches have been used frequently in cheese ripening include the addition of enzymes,attenuated starter cells,elevated ripening temperatures,high pressure treatment and so on,however there are some defects for each other.Non-starter lactic acid bacteria(NSLAB) could accelerate cheese ripening,so it become one of focus of the methods to accelerate cheese ripening.The roles of microorganisms on the cheesemaking and ripening,the reason for using adjunct culture and its advances will be surveyed in this paper.
Objective To investigate the effect of cell wall components of L.casei LC2W on phagocytic activity of murine macrophage cells in vitro.Methods Enhancement of the activity of Lactate Dehydrogenase(LDH),phagocytic activity to neutral red as well as enteropathogeic pathogens of murine macrophage RAW264.7 cells challenged with different levels of teichoic acid(TA)or peptidoglycan(PG),two predominant components of the cell wall of the cell L.casei LC2W,were compared with those macrophage cells challenged without TA or PG.Results The activity of LDH,phagocytic activity to neutral red as well as enteropathogeic pathogens were significantly enhanced,in a dosage-dependent manner,in murine macrophage RAW264.7 cells challenged with different levels of TA or PG.No obvious difference in phagocytic activity to neutral red existed in RAW264.7 cells challenged with LactobacillusTA and those cells challenged with PG.On the contrary,TA showed significant higher ability in enhancing LDH activity than PG.Simultaneously,TA and PG demonstrated similar ability in enhancing phagocytic activity of RAW264.7 cells to enteropathogenic microbes,when the latter were challenged with either TA or PG at the concentration of 50ug per milliliter.The maximized phagocytosis was reached after the challenged RAW264.7 cells were incubated with either Escherichia coli EPEC AS 1.72 or Salmonella enteritis AS 50041.Conclusion TA and PG of the cell wall of L.casei LC2W could significantly enhance the activity of LDH,phagocytic activity to neutral red as well as enteropathogeic pathogens,in a dosage-dependent manner,in murine macrophage RAW264.7 cells.
Objective To extract and identify the S-layer proteins of Lactobacillus casei LC2W that associates with adhesion and preliminarily study the mechemism of LC2W adhesion on MKN-45 cells.Method S-layer proteins were extracted by LiCl and isolated by Sephadex G-75.Then the adhesion assay,electron microscopic observation and SDS-PAGE were used to identify the S-layer protein associated with adhesion.Result After the treatment of LiCl,electron microscopic observation showed that the surface of LC2W was rough but the cells were still in their integrity.The ability of adhesion to MKN-45 cells was significantly reduced.Slayer proteins of LC2W were composed of three proteins with molecular weights of 41.6,63.5 and 66.2 kDa,respectively.After the isolation by Sephadex G-75,it was found that the 41.6 kDa fraction could significantly improve the adhesion of LC2W treated by LiCl and the adhesive ability of the treated cells amounted to the level of the normal ones.Conclusion The S-layer proteins were involved in the adhesion of LC2W on MKN-45 and the active component was the protein with molecular weight of 41.6 kDa.
Existing current balancing strategy based on single current threshold adjustment is not suitable for interleaved constant frequency hysteresis (CFH) buck converter with threshold width adjustment (TWA). To address this issue, this paper proposes a threshold midpoint adjustment (TMA) circuit to achieve current balancing. Firstly, hysteresis comparison in the TWA is linearized to precisely design the TWA loop. Secondly, to ensure the steady-state accuracy and stability of TMA loop, a multi-phase coupled small signal model (MPC-SSM) is proposed with consideration of coupling effect among multiple phases. Finally, based on 180nm BCD process, TMA for current balancing is realized on a four-phase interleaved CFH buck converter. FOM for voltage ripple is four times of single-phase buck converter, which means better ripple suppression. Power level is twice of single-phase buck converter.
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