A Study on Pulsed Power Supply based on Separate Excitation

© ASEE 2007Regular power supply cannot be used for some special applications such as discharging plasma generator, air purification system, medical discharging equipment, etc. Instead, a special low-power high-voltage pulsed power supply is required. In this paper, the design and simulation of a separate excited pulse power supply are proposed. The power supply can produce high-voltage small-current pulses adaptive to different loads. The working principle of the power supply is analyzed. A comparison between this power supply and other pulsed power supply based on capacitance energy storage is discussed. The circuit implementation of power supply is proposed. The key component for the power supply, pulse transformer, as well as other components is studied in detail. Based on the analysis, an optimized design of the power supply is proposed. Computer simulation is used to verify the performance of the designed power supply, such as the output characteristics under different load resistances, the pulse frequency and the duty ratio. Simulation results demonstrate the effectiveness of the designed power supply. Some possible performance improvements on the power supply are also suggested. The designed power supply can satisfy the requirements for commercial applications such as plasma generation and air purification system

Natural antisense transcripts regulate the neuronal stress response and excitability

Neurons regulate ionic fluxes across their plasma membrane to maintain their excitable properties under varying environmental conditions. However, the mechanisms that regulate ion channels abundance remain poorly understood. Here we show that pickpocket 29 (ppk29), a gene that encodes a Drosophila degenerin/epithelial sodium channel (DEG/ENaC), regulates neuronal excitability via a protein-independent mechanism. We demonstrate that the mRNA 3′UTR of ppk29 affects neuronal firing rates and associated heat-induced seizures by acting as a natural antisense transcript (NAT) that regulates the neuronal mRNA levels of seizure (sei), the Drosophila homolog of the human Ether-à-go-go Related Gene (hERG) potassium channel. We find that the regulatory impact of ppk29 mRNA on sei is independent of the sodium channel it encodes. Thus, our studies reveal a novel mRNA dependent mechanism for the regulation of neuronal excitability that is independent of protein-coding capacity. DOI: http://dx.doi.org/10.7554/eLife.01849.00

Effects of Pure Oxygen on the Rate of Skin Browning and Energy Status in Longan Fruit

Postharvest pericarp browning is one of the main problems resulting in reduced shelf life of longan fruit. Experiments were conducted to examine the changes in concentrations of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP), energy charge levels and activities of polyphenol oxidase (PPO) and peroxidase (POD) in relation to pericarp browning of longan fruit. Fruit kept for 6 days in pure oxygen atmosphere at 28 C showed lower browning indices and higher ATP concentrations but lower AMP concentrations and higher respiratory rates, compared to those kept in air. While energy charge decreased during storage, the decrease was delayed markedly by exposure to pure oxygen. There was a lower energy charge in the browned fruit, which was associated with rapid increase in malondialdehyde concentration. Enhanced respiration of longan fruit exposed to pure oxygen can result in the production of ATP. However, fruit exposed to pure oxygen exhibited higher activities of PPO and POD, which was not associated with reduced skin browning inhibition. These results supported the hypothesis that skin browning of postharvest longan fruit may be a consequence of membrane injury caused by the lack of maintenance energy

Effects of Pure Oxygen on the Rate of Skin Browning and Energy Status in Longan Fruit

Postharvest pericarp browning is one of the main problems resulting in reduced shelf life of longan fruit. Experiments were conducted to examine the changes in concentrations of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP), energy charge levels and activities of polyphenol oxidase (PPO) and peroxidase (POD) in relation to pericarp browning of longan fruit. Fruit kept for 6 days in pure oxygen atmosphere at 28 C showed lower browning indices and higher ATP concentrations but lower AMP concentrations and higher respiratory rates, compared to those kept in air. While energy charge decreased during storage, the decrease was delayed markedly by exposure to pure oxygen. There was a lower energy charge in the browned fruit, which was associated with rapid increase in malondialdehyde concentration. Enhanced respiration of longan fruit exposed to pure oxygen can result in the production of ATP. However, fruit exposed to pure oxygen exhibited higher activities of PPO and POD, which was not associated with reduced skin browning inhibition. These results supported the hypothesis that skin browning of postharvest longan fruit may be a consequence of membrane injury caused by the lack of maintenance energy

Plasma exosomal miR-320d, miR-4479, and miR-6763-5p as diagnostic biomarkers in epithelial ovarian cancer

BackgroundExosomal miRNA had been proved as the promising biomarkers for multiple cancers including epithelial ovarian cancer (EOC). This study aimed to validate the diagnostic accuracy of exosomal miR-320d, miR-4479, and miR-6763-5p for EOC.Materials and methodsExosomes isolated from the plasma by ultracentrifugation were verified using TEM, qNano and western blot. MiRNAs sequencing was used to screen out the differential exosomal miRNAs and miR-320d, miR-4479, and miR-6763-5p were selected as candidates, which were further verified by RT-qPCR in 168 healthy donors and 161 primary EOC patients. Besides, the diagnostic accuracy of these three exosomal miRNAs were evaluated using the receiver operating characteristic curve (ROC).ResultsMiRNAs sequencing revealed 95 differential exosomal miRNAs between EOC patients and healthy donors. Subsequently, exosomal miR-320d, miR-4479, and miR-6763-5p were significantly down regulated in EOC patients compared with healthy controls and benign patients. More importantly, these three miRNAs could serve as circulating diagnostics biomarkers for EOC, possessing areas under the curve (AUC) of 0.6549, 0.7781, and 0.6834, respectively. Moreover, these three exosomal miRNAs levels were closely associated with lymph node metastasis, meanwhile exosomal miR-320d and miR-4479 expression was related to tumor stage.ConclusionExosomal miR-320d, miR-4479, and miR-6763-5p might serve as potential biomarkers for EOC

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Neuronal Functions of the Drosophila DEG/ENaC Channel ppk29

Degenerin/Epithelial Na+ channels (DEG/ENaC) represent a diverse family of animal-specific cation channels that play a key role in regulating ionic currents across epithelial barriers. While several family members are also enriched in the nervous system, their physiological functions in these tissues are not as well defined. To better understand the functions of DEG/ENaCs in a genetically tractable system, I used Drosophila melanogaster as a model system to investigate the function of Drosophila DEG/ENaC subunit pickpocket 29 (ppk29) in neuronal plasticity. My thesis work demonstrated that ppk29 regulates neuronal excitability via a protein-independent mechanism. By using behavioral, genetic, molecular, and neurophysiological tools I demonstrated that the 3\u27UTR of the ppk29 mRNA affects neuronal firing rates and associated heat-induced seizures by acting as a natural antisense transcript (NAT) that regulates the neuronal mRNA level of seizure (sei), the Drosophila homolog of the human Ether-à-go-go Related Gene (hERG) potassium channel. Surprisingly, I found that the regulatory impact of ppk29 mRNA on sei is independent of the sodium channel it encodes. Furthermore, I discovered that the PPK29 protein is required presynaptically for normal synaptic transmission at the larval neuromuscular junction (NMJ). By using genetic and neurophysiological tools, I demonstrated that PPK29 is necessary in presynaptic motor neurons for stimulus-evoked, but not spontaneous, neurotransmitter release, without an apparent impact on gross synaptic development or morphology. Additionally, my work demonstrated that PPK29 activity contributes to the modulatory effects of FMRFamide-like peptides on synaptic facilitation, suggesting this DEG/ENaC channel likely acts as important neuropeptidergic modulators in synaptic physiology. In summary, I have identified two independent mechanisms by which a single gene can affect neuronal plasticity: the first is an mRNA-dependent homeostatic response to stress; the second occurs via protein-dependent contribution to synaptic transmission and peptidergic facilitation

Nitrogen addition regulates soil nematode community composition through ammonium suppression

Nitrogen (N) enrichment resulting from anthropogenic activities has greatly changed the composition and functioning of soil communities. Nematodes are one of the most abundant and diverse groups of soil organisms, and they occupy key trophic positions in the soil detritus food web. Nematodes have therefore been proposed as useful indicators for shifts in soil ecosystem functioning under N enrichment. Here, we monitored temporal dynamics of the soil nematode community using a multi-level N addition experiment in an Inner Mongolia grassland. Measurements were made three years after the start of the experiment. We used structural equation modeling (SEM) to explore the mechanisms regulating nematode responses to N enrichment. Across the N enrichment gradient, significant reductions in total nematode abundance, diversity (H' and taxonomic richness), maturity index (MI), and the abundance of root herbivores, fungivores and omnivores-predators were found in August. Root herbivores recovered in September, contributing to the temporal variation of total nematode abundance across the N gradient. Bacterivores showed a hump-shaped relationship with N addition rate, both in August and September. Ammonium concentration was negatively correlated with the abundance of total and herbivorous nematodes in August, but not in September. Ammonium suppression explained 61% of the variation in nematode richness and 43% of the variation in nematode trophic group composition. Ammonium toxicity may occur when herbivorous nematodes feed on root fluid, providing a possible explanation for the negative relationship between herbivorous nematodes and ammonium concentration in August. We found a significantly positive relationship between fungivores and fungal phospholipid fatty acids (PLFA), suggesting bottom-up control of fungivores. No such relationship was found between bacterivorous nematodes and bacterial PLFA. Our findings contribute to the understanding of effects of N enrichment in semiarid grassland on soil nematode trophic groups, and the cascading effects in the detrital soil food web