Designing and Implementing a Micro-controller based Primary-side Sensing Flyback Converter for LEDs Driver

The fast development of LED and its applications has enabled a new generation of lighting device with higher efficiency and long lifespan. By employing a primary-side sensing flyback converter and the PIC18F micro-controller series, an LED driver could achieve two important features: (1) the compatibility with the available lighting fixtures, and (2) reducing unit price. The flyback converter was chosen for its simplicity, competitive low cost, and its ability to provide a constant output current, a necessarily important factor to an LED driver. Meanwhile, the PIC18F micro-controller series offer numerous advanced features which include but not limited to pulse-width modulation (PWM), 10-bit 13-channel Analog-to-Digital Converter (ADC) etc., which suitably meet the requirements for regulating a primary-side sensing flyback converter. The design process was first conducted in simulation stage with aid from Matlab®-Simulink and Cadence OrCAD Capture CIS (PSpice). By using PI based control scheme and making full use of built-in Analog Behavioral Modelling (ABM) blocks, the simulation-relevant difficulties due to lacking of appropriate model for the PIC18F series micro-controller were completely solved. The simulation results matched well with the intended design specifications: the output voltage is 32 VDC while the load current is 350 mA. More importantly, the simulation results demonstrated the feasibility of deploying a primary-side sensing flyback converter in conjunction with a PIC18F micro-controller as an LED driver. Next, a demo printed-circuit board (PCB) was layout by using OrCAD PCB Editor. Finally, the PIC18F4550 micro-controller was programmed to undertake control tasks of the LED driver. The experimental results reflect the project\u27s success with all the parts of the driver harmoniously work as expected

Chemical Components of Essential Oils From the Leaves of Seven Species Belonging to Rutaceae Family from Binh Chau-Phuoc Buu Nature Reserve, Vietnam

Several plant species of the Rutaceae family are medicinal plants, oil bearing and food crops. To provide more information for utilization of some species of this family in Binh Chau-Phuoc Buu Nature Reserve, we extracted essential oils from the leaves of seven species of the Rutaceae family: Acronychia pedunculata (L.) Miq., Atalantia citroides Pierre ex Guillaumin, Clausena excavata Burm.f., Glycosmis pentaphylla (Retz.) DC., Luvunga scandens (Roxb.) Buch.-Ham. ex Wight & Arn, Melicope pteleifolia (Champ. ex Benth.) T.G. Hartley, and Micromelum sp., via hydrodistillation, and identified their components using GC/MS analysis. A total of 60 compounds were identified from essential oils of seven species. The main components of the essential oils isolated from five species, including A. pedunculata, C. excavata, M. pteleifolia, G. pentaphylla, and Micromelum sp., were caryophyllene (57.63% and 55.41% in A. pedunculata and C. excavata, respectively), 1,9-decadiyne (32.59%, M. pteleifolia), β-ocimene (23.10%, G. pentaphylla), and 3-carene (58.03%, Micromelum sp.). Additionally, this study revealed the chemical composition of essential oils of L. scandens and A. citroides for the first time. The main constituent of A. citroides was 7-oxabicyclo[4.1.0] heptane, 3-oxiranyl- (53.91%) and that of L. scandens was caryophyllene (34.66%). These findings provide the basis for further application of these species in medicine

DETERMINACIÓN DE CONDICIONES OPERATIVAS DE BIOTECNOLOGÃA VEGETAL IN VITRO PARA LA PROPAGACIÓN DEL HELECHO PLATYCERIUM

Este trabajo presenta el establecimiento de las condiciones operativas del Laboratorio de Biotecnología Vegetal in vitro, para la propagación del helecho Platycerium bifurcatum, con el objetivo de realizar los protocolos necesarios para la recepción del material vegetal, desinfección del mismo, desinfectación del sitio e instrumental, preparación y almacenamiento de medios, siembra y transferencia de dicho helecho; siendo un referente teórico para futuras investigaciones por parte de los estudiantes de la Facultad de Ingeniería, Programa de Ingeniería Agroindustrial. Este helecho reviste importancia ya que es un referente paisajista de Colombia, y por ello, el presente trabajo gira en torno a su masificación basada en la biotecnología in vitro como soporte

Transcriptome analysis of copper stress response in rice seedling using DNA microarray

Heavy metal contamination along with the increase in food demand are a primary concern in Vietnam and all over the world. In order to enhance crop tolerance to unfavorable cultivation conditions including heavy metal toxicity, understanding of plant response system under the effect of heavy metals is necessary. In the current study, physiological, biochemical and transcriptomic changes of rice seedings (Oryza sativa L. cv. IR64) were investigated under copper (Cu) stress. Root elongation and root fresh weight were decreased whereas accumulation of copper in root was enhanced significantly with increasing copper concentration from 2.5 to 15 M. In addition, copper induced endogenous reactive oxygen species (ROS) generation and activated isoenzymes of superoxide dismutase (SOD) and catalase (CAT). The molecular mechanism of rice roots in response to copper toxicity at mRNA expression level was analyzed by microarray technique. Functions and roles of genes were also analyzed by bioinformatic tools AgriGO and MapMan. Gene ontology analysis revealed that 1900 Cu responsive genes were involved in phytohormones, reactive oxygen species, signaling pathways, transcription factors, transport activities, antioxidant defense systems. Through phytohormones and reactive oxygen species, Cu may inhibit rice root growth. Phytohormones and reactive oxygen species can also be signal molecules in signaling pathways with the participation of mitogen-activated protein kinase (MAPK) cascades, and transcription factors in response to Cu stress. Detoxification and protection mechanisms may involve transport activities and antioxidant defense systems during Cu treatment. These results may provide new insights into mechanisms of rice plant to tolerate with Cu toxicity conditions

A comprehensive study on the efficacy of a wearable sleep aid device featuring closed-loop real-time acoustic stimulation

Difficulty falling asleep is one of the typical insomnia symptoms. However, intervention therapies available nowadays, ranging from pharmaceutical to hi-tech tailored solutions, remain ineffective due to their lack of precise real-time sleep tracking, in-time feedback on the therapies, and an ability to keep people asleep during the night. This paper aims to enhance the efficacy of such an intervention by proposing a novel sleep aid system that can sense multiple physiological signals continuously and simultaneously control auditory stimulation to evoke appropriate brain responses for fast sleep promotion. The system, a lightweight, comfortable, and user-friendly headband, employs a comprehensive set of algorithms and dedicated own-designed audio stimuli. Compared to the gold-standard device in 883 sleep studies on 377 subjects, the proposed system achieves (1) a strong correlation (0.89 ± 0.03) between the physiological signals acquired by ours and those from the gold-standard PSG, (2) an 87.8% agreement on automatic sleep scoring with the consensus scored by sleep technicians, and (3) a successful non-pharmacological real-time stimulation to shorten the duration of sleep falling by 24.1 min. Conclusively, our solution exceeds existing ones in promoting fast falling asleep, tracking sleep state accurately, and achieving high social acceptance through a reliable large-scale evaluation

Quantifying the Emergence of Dengue in Hanoi, Vietnam: 1998–2009

Dengue is the most common vector-borne viral disease of humans, causing an estimated 50 million cases per year. The number of countries affected by dengue has increased dramatically in the last 50 years and dengue is now a major public health problem in large parts of the tropical and subtropical world. It is of considerable importance to understand the factors that determine how dengue becomes newly established in areas where the risk of dengue was previously small. Hanoi in North Vietnam is a large city where dengue appears to be emerging. We analyzed 12 years of dengue surveillance data in order to characterize the temporal and spatial epidemiology of dengue in Hanoi and to establish if dengue incidence has been increasing. After excluding the two major outbreak years of 1998 and 2009 and correcting for changes in population age structure over time, we found there was a significant annual increase in the incidence of notified dengue cases over the period 1999–2008. Dengue cases were concentrated in young adults in the highly urban central areas of Hanoi. This study indicates that dengue transmission is increasing in Hanoi and provides a platform for further studies of the underlying drivers of this emergence

Structure of general-population antibody titer distributions to influenza A virus.

Seroepidemiological studies aim to understand population-level exposure and immunity to infectious diseases. Their results are normally presented as binary outcomes describing the presence or absence of pathogen-specific antibody, despite the fact that many assays measure continuous quantities. A population's natural distribution of antibody titers to an endemic infectious disease may include information on multiple serological states - naiveté, recent infection, non-recent infection, childhood infection - depending on the disease in question and the acquisition and waning patterns of immunity. In this study, we investigate 20,152 general-population serum samples from southern Vietnam collected between 2009 and 2013 from which we report antibody titers to the influenza virus HA1 protein using a continuous titer measurement from a protein microarray assay. We describe the distributions of antibody titers to subtypes 2009 H1N1 and H3N2. Using a model selection approach to fit mixture distributions, we show that 2009 H1N1 antibody titers fall into four titer subgroups and that H3N2 titers fall into three subgroups. For H1N1, our interpretation is that the two highest-titer subgroups correspond to recent and historical infection, which is consistent with 2009 pandemic attack rates. Similar interpretations are available for H3N2, but right-censoring of titers makes these interpretations difficult to validate

Awareness and preparedness of healthcare workers against the first wave of the COVID-19 pandemic: A cross-sectional survey across 57 countries.

BACKGROUND: Since the COVID-19 pandemic began, there have been concerns related to the preparedness of healthcare workers (HCWs). This study aimed to describe the level of awareness and preparedness of hospital HCWs at the time of the first wave. METHODS: This multinational, multicenter, cross-sectional survey was conducted among hospital HCWs from February to May 2020. We used a hierarchical logistic regression multivariate analysis to adjust the influence of variables based on awareness and preparedness. We then used association rule mining to identify relationships between HCW confidence in handling suspected COVID-19 patients and prior COVID-19 case-management training. RESULTS: We surveyed 24,653 HCWs from 371 hospitals across 57 countries and received 17,302 responses from 70.2% HCWs overall. The median COVID-19 preparedness score was 11.0 (interquartile range [IQR] = 6.0-14.0) and the median awareness score was 29.6 (IQR = 26.6-32.6). HCWs at COVID-19 designated facilities with previous outbreak experience, or HCWs who were trained for dealing with the SARS-CoV-2 outbreak, had significantly higher levels of preparedness and awareness (p<0.001). Association rule mining suggests that nurses and doctors who had a 'great-extent-of-confidence' in handling suspected COVID-19 patients had participated in COVID-19 training courses. Male participants (mean difference = 0.34; 95% CI = 0.22, 0.46; p<0.001) and nurses (mean difference = 0.67; 95% CI = 0.53, 0.81; p<0.001) had higher preparedness scores compared to women participants and doctors. INTERPRETATION: There was an unsurprising high level of awareness and preparedness among HCWs who participated in COVID-19 training courses. However, disparity existed along the lines of gender and type of HCW. It is unknown whether the difference in COVID-19 preparedness that we detected early in the pandemic may have translated into disproportionate SARS-CoV-2 burden of disease by gender or HCW type