PV-Transformer-Less Inverter Topology for Battery-Equivalent DC Supply from Leakage Current

Solar panels used for electricity generation have got inverters as their core components. Such inverters are made from switching devices coupled with additional circuit component configured in a transformer-less topology in recent reported works. A transformer-less topology suffers from the drawbacks of lack of isolation leading to leakage current flow from various points of it down to ground. The leakage in inverters might be troublesome as it may lead to loss in power, and may cause malfunctioning of analog devices normally used in power inverters. In this work, we identify possible leakage currents in a given transformer-less topology using the circuit analysis principles. The conversion of so obtained leakage currents into a useful DC voltage is carried out in this work. This work focuses on converting leakage current into small DC voltage in the range of ~1.1004V using recently reported rectifier circuits, supplying a load of 200Ω in the mW range. Although small in magnitude, such voltage sources could be used for battery charging purposes or driving small loads

Antioxidant compounds, antioxidant activities, and mineral contents among underutilized vegetables

Natural sources may be a method to introduce antioxidants in the human diet. Portulaca oleracea L., Peperomia pellucida L., and Trianthema portulacastrum L are underutilized leafy vegetables. The plants may be sources for total phenolic (TPC), total flavonoid (TFC), total carotenoid (TCC), and β-carotene but information is lacking. Antioxidant activity, ferric reducing antioxidant power (FRAP), and 1,1-diphenyl-2-picrylhydrazyl (DPPH), and macro- and microminerals contents were investigated in P. oleracea, P. pellucida and T. portulacastrum. Trianthema portulacastrum had the highest TPC (1.34 ± 0.13 mg∙g−1), TFC (0.58 ± 0.08 mg∙g−1), TCC (0.14 ± 0.01 mg∙g−1), and β-carotene (0.94 ± 0.18 mg∙g−1) values. The antioxidant activity and FRAP assay were highest in P. oleracea (0.91 ± 0.09 mg∙g−1); the DPPH assay for P. pellucida was highest (IC50 = 7 µg∙mL−1). The amount of K was highest in P. oleracea (55.470 ± 0.481 g∙kg−1). The amount of Mn was highest in P. pellucida (0.251 ± 0.002 g∙kg−1). The individual underutilized vegetables may be able to supply some antioxidant compounds and mineral contents for the human diet

Millihertz quasi-periodic oscillations and broad iron line from LMC X-1

We study the temporal and energy spectral characteristics of the persistent black hole Xray binary LMC X-1 using two XMM–Newton and a Suzaku observation. We report the discovery of low-frequency (∼26–29 m Hz) quasi-periodic oscillations (QPOs). We also report the variability of the broad iron Kα line studied earlier with Suzaku. The QPOs are found to be weak with fractional rms amplitude in the ∼1–2 per cent range and quality factor Q ∼ 2–10. They are accompanied by weak red noise or zero-centred Lorentzian components with rms variability at the ∼1–3 per cent level. The energy spectra consist of three varying components – multicolour disc blackbody (kTin ∼ 0.7–0.9 keV), high-energy power-law tail ( ∼ 2.4–3.3) and a broad iron line at 6.4–6.9 keV. The broad iron line, the QPO and the strong power-law component are not always present. The QPOs and the broad iron line appear to be clearly detected in the presence of a strong power-law component. The broad iron line is found to be weaker when the disc is likely truncated and absent when the power-law component almost vanished. These results suggest that the QPO and the broad iron line together can be used to probe the dynamics of the accretion disc and the corona. Key words: accretion, accretion discs – black hole physics – binaries: spectroscopic – stars

Evaluation of phenolics, capsaicinoids, antioxidant properties, and major macro-micro minerals of some hot and sweet peppers and ginger land-races of Malaysia

There are compelling evidences that oxidative stress plays important role in age‐related neurodegenerative diseases and natural food‐derived dietary antioxidants appear to be the first line of defence to take care of the oxidative stress. The analysis results of this study showed that Cili Burung of the hot pepper landraces contained the highest amount of TPC (1.00 mg/g DW), TFC (0.17 mg/g DW), capsaicinoids (0.05 mg/g), and the highest FRAP activity (439 mg/g DW). However, DPPH assay revealed the highest DPPH scavenging activity (IC50 = 250 μg/ml) in Halia Bara rhizome. Rhizomes of both landraces of ginger showed a significant amount of capsaicinoids. Hot pepper Cili Ungu (5.50 g/kg) and sweet pepper Cili Kulai had the highest P contents (~5.5 g/kg). Halia Bentong ginger rhizome had the highest content of K (33.84 g/kg); however, Halia Bentong ginger roots had remarkably greater contents of Ca (10.96 g/kg). Ginger rhizomes and roots had greater contents of micro minerals compared to hot and sweet chili peppers. Ginger roots contained good amounts of bioactive compounds and mineral nutrients indicating its commercial value

Interfacial Microstructure, Microhardness and Tensile Properties of Al Micro-Particle Doped Sn-9Zn Eutectic Pb-Free Solder Alloy for Microelectronics Applications

In this study, the effect of Al microparticles (10µm) to Sn9Zn eutectic solder, were examined in order to investigate the microstructural and mechanical properties as well as thermal behavior of the newly developed ternary solder alloys. Here, an approach to prepare a microcomposite solder alloy by mixing Al with a molten SnZn solder alloy was developed. Thecomposite solder was prepared by mechanically mixing Al microparticles into the Sn–9Zn alloy melt to ensure a homogeneous distribution of the reinforcing particles. The Al particles reacted with the Zn and formed intermetallic compounds (IMC) with the eutectic solder alloy. The microstructures of newly developed ternary Sn 9ZnxAl solder alloys contain fine needlelike αZn phase with some IMCs dispersed in the βSn matrix. The compact shaped Al6Zn3Sn IMC uniformly distributed in the βSn phase which results in an increase in the tensile strength, dueto the second phase dispersed strengthening mechanism. As the Al content increases, the microhardness of the Sn9ZnxAl ternary solder alloys also improves due to the presence of harder IMC in the microstructure. The thermal behavior was found in the sustainable working range for these composite solder

Measuring flammability of crops, pastures, fruit trees, and weeds: A novel tool to fight wildfires in agricultural landscapes

Fires on agricultural land account for 8–11 % of the total number of fires that occur globally. These fires burn through various crops, pastures, and native vegetation on farms, causing economic and environmental losses. Fire management on farms will be aided by understanding the flammability of plant species as this would allow the design of low-flammability agricultural landscapes, but flammability data on large numbers of agricultural species are lacking. Many crop and vegetable species are assumed to be low in flammability, but this has rarely been tested. Therefore, we examined the shoot and whole-plant flammability of 47 plant taxa commonly grown on farms in Canterbury, New Zealand, which included many globally common temperate agricultural crops. We demonstrated that most of the agricultural species were low to very low in flammability, with many of them (24 taxa; 51 %) not igniting in the experimental burning. Among different crop types, fruit crops and cereals had significantly higher flammability, while taxa categorized as vegetable crops, grazing herbs, pasture grasses, pasture legumes, and weeds were lower in flammability. We further showed that taxa with lower moisture content, higher retention of dead material and faster moisture loss rates were higher in flammability. The strong variation of flammability between the studied taxa suggests that the selection of suitable low flammability species and strategic redesign of agricultural landscapes with fire-retardant planting can be a useful tool to reduce fire hazards and impacts of wildfires in agricultural landscapes

The NANOGrav 12.5 yr Data Set: Observations and Narrowband Timing of 47 Millisecond Pulsars

We present time-of-arrival (TOA) measurements and timing models of 47 millisecond pulsars observed from 2004 to 2017 at the Arecibo Observatory and the Green Bank Telescope by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). The observing cadence was three to four weeks for most pulsars over most of this time span, with weekly observations of six sources. These data were collected for use in low-frequency gravitational wave searches and for other astrophysical purposes. We detail our observational methods and present a set of TOA measurements, based on narrowband analysis, in which many TOAs are calculated within narrow radio-frequency bands for data collected simultaneously across a wide bandwidth. A separate set of wideband TOAs will be presented in a companion paper. We detail a number of methodological changes, compared to our previous work, which yield a cleaner and more uniformly processed data set. Our timing models include several new astrometric and binary pulsar measurements, including previously unpublished values for the parallaxes of PSRs J1832−0836 and J2322+2057, the secular derivatives of the projected semimajor orbital axes of PSRs J0613−0200 and J2229+2643, and the first detection of the Shapiro delay in PSR J2145−0750. We report detectable levels of red noise in the time series for 14 pulsars. As a check on timing model reliability, we investigate the stability of astrometric parameters across data sets of different lengths. We also report flux density measurements for all pulsars observed. Searches for stochastic and continuous gravitational waves using these data will be subjects of forthcoming publications

Effects of flowering behavior and pod maturity synchrony on yield of mungbean [Vigna radiata (L.) Wilczek].

A number of experiments were set up to assess the flower production and flowering pattern in synchrony with pod maturity and seed yield in twelve mungbean genotypes. Synchrony of pod maturity was measured based on percentage of mature pods at first harvest, where; synchrony (>90% mature pods), partial synchrony (80-90% mature pods) and asynchrony (<80% mature pods). Results revealed that genotypes that produced maximal opened flowers within 10-15 days, and ceased flowering within 15-20 days after first flowering (DAF), have synchrony in pod maturity. Additionally, seed yield was strongly correlated with the number of opened flowers and number of produced mature pods. Four genotypes showed synchrony in pod maturity which accompanied with cessation of flower production at 10-15 DAF, but produced lower yields due to fewer opened flowers. In contrast, the remaining genotypes showed partial synchrony or asynchrony in pod maturity due to longer flowering durations, with higher number of opened flowers and seed yield. These results indicate that synchrony in pod maturity and seed yield in mungbean is inversely related

Multi-resonant high-Q plasmonic metasurfaces

Resonant metasurfaces are devices composed of nanostructured sub-wavelength scatterers that generate narrow optical resonances, enabling applications in filtering, nonlinear optics, and molecular fingerprinting. It is highly desirable for these applications to incorporate such devices with multiple, high-quality-factor resonances; however, it can be challenging to obtain more than a pair of narrow resonances in a single plasmonic surface. Here, we demonstrate a multi-resonant metasurface that operates by extending the functionality of surface lattice resonances, which are the collective responses of arrays of metallic nanoparticles. This device features a series of resonances with high quality factors (Q ~ 40), an order of magnitude larger than what is typically achievable with plasmonic nanoparticles, as well as a narrow free spectral range. This design methodology can be used to better tailor the transmission spectrum of resonant metasurfaces and represents an important step towards the miniaturization of optical devices.Comment: 8 pages, 4 figures, includes MATLAB code in Supplementary Material