738 research outputs found
Mainstreaming menstrual hygiene management: lessons from a decade of programme and policy work
Proper menstrual hygiene management is integral to the dignity and health of women and girls. However, it is a neglected issue both in the WASH and health sectors, leading to a crisis of knowledge, facilities and hygienic practice. This briefing paper describes the initiatives taken by the Bangladesh country programme of the international non-governmental organisation WaterAid. As one of the pioneers of Menstrual Hygiene Management (MHM) in Bangladesh, WaterAid’s experiences hold important lessons for those currently working on the issue, and looking to take it forward to make sustainable impact
Increasing cropping intensity in saline coastal zone soils of Bangladesh: The challenges of fitting maize between wet soils at establishment and saline, dry soils after silking
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A Multilevel Inverter with Minimized Components Featuring Self-balancing and Boosting Capabilities for PV Applications
Shot Noise Enhancement in Resonant Tunneling Structures in a Magnetic Field
We have observed that the shot noise of tunnel current, I, in
GaSb-AlSb-InAs-AlSb-GaSb double-barrier structure under a magnetic field can
exceed 2qI. The measurements were done at T=4K in fields up to 5T parallel to
the current. The noise enhancement occurred at each of the several
negative-differential conductance regions induced by the tunneling of holes
through Landau levels in the InAs quantum well. The amount of the enhancement
increased with the strength of the negative conductance and reached values up
to 8qI. These results are explained qualitatively by fluctuations of the
density of states in the well, but point out the need for a detailed theory of
shot noise enhancement in resonant tunneling devices.Comment: 4 pages, RevTex, 3 figure
Chemical and biological investigations of Delonix regia (Bojer ex Hook.) Raf.
U radu je opisana izolacija pet sastojaka petroleterske i diklormetanske frakcije metanolnog ekstrakta kore biljke Delonix regia: lupeol (1), epilupeol (2), β-sitosterol (3), stigmasterol (4) i p-metoksibenzaldehid (5). Nadalje, testirano je antimikrobno djelovanje različitih ekstrakata difuzijskom metodom na disku (15 μg mm2). Zone inhibicije za sastojke topljive u petroleteru, tetraklormetanu i diklormetanu bile su 914 mm, 1113 mm, odnosno 920 mm, dok je zona inhibicije standarda kanamicina bila 2025 mm. U biološkom pokusu smrtnosti morskih kozica najveću toksičnost pokazali su spojevi topljivi u tetraklormetanu (LC50 = 0,83 μg mL1), dok je topljivost sastojaka topljivih u petroleteru i diklormetanu bila LC50 14,94, odnosno 3,29 μg mL1, a standarda vinkristin sulfata 0,812 μg mL1. Ovo je prvo izvješće o izolaciji sastojaka, antimikrobnom djelovanju i citotoksičnosti biljke D. regia.In this study five compounds, lupeol (1), epilupeol (2), β-sitosterol (3), stigmasterol (4) and p-methoxybenzaldehyde (5) were isolated from the petroleum ether and dichloromethane fractions of a methanolic extract of the stem bark of Delonix regia. Antimicrobial screening of the different extracts (15 μg mm2) was conducted by disc diffusion method. The zones of inhibition demonstrated by the petroleum ether, carbon tetrachloride and dichloromethane fractions ranged from 914 mm, 1113 mm and 920 mm, respectively, compared to kanamycin standard with the zone of inhibition of 2025 mm. In brine shrimp lethality bioassay, the carbon tetrachloride soluble materials demonstrated the highest toxicity with LC50 of 0.83 μg mL1, while petroleum ether and dichloromethane soluble partitionates of the methanolic extract revealed LC50 of 14.94 and 3.29 μg mL1, respectively, in comparison with standard vincristine sulphate with LC50 of 0.812 μg mL1. This is the first report on compounds separation from D. regia, their antimicrobial activity and cytotoxicity
Common-Ground-Type Single-Source High Step-Up Cascaded Multilevel Inverter for Transformerless PV Applications
The cascaded multilevel inverter (CMI) is one type of common inverter in industrial applications. This type of inverter can be synthesized either as a symmetric configuration with several identical H-bridge (HB) cells or as an asymmetric configuration with non-identical HB cells. In photovoltaic (PV) applications with the CMI, the PV modules can be used to replace the isolated dc sources; however, this brings inter-module leakage currents. To tackle the issue, the single-source CMI is preferred. Furthermore, in a grid-tied PV system, the main constraint is the capacitive leakage current. This problem can be addressed by providing a common ground, which is shared by PV modules and the ac grid. This paper thus proposes a topology that fulfills the mentioned requirements and thus, CMI is a promising inverter with wide-ranging industrial uses, such as PV applications. The proposed CMI topology also features high boosting capability, fault current limiting, and a transformerless configuration. To demonstrate the capabilities of this CMI, simulations and experimental results are provided
Enhanced shot noise in resonant tunneling: theory and experiment
We show that shot noise in a resonant tunneling diode biased in the negative
differential resistance regions of the I-V characteristic is enhanced with
respect to ``full'' shot noise. We provide experimental results showing a Fano
factor up to 6.6, and show that it is a dramatic effect caused by
electron-electron interaction through Coulomb force, enhanced by the particular
shape of the density of states in the well. We also present numerical results
from the proposed theory, which are in agreement with the experiment,
demonstrating that the model accounts for the relevant physics involved in the
phenomenon.Comment: 4 pages, 4 figure
A New Control Scheme for Three-Phase Non-Isolated Grid Feeding PV Inverter
The use of control algorithms in inverter topologies is becoming more attractive for integration of wind and photovoltaic (PV) energy with a grid. Among the various inverters, the non-isolated inverter topology has gotten a huge attention for fixing the problem of leakage current issue with other inverters. In this paper, a linear control strategy is offered for the grid connected non-isolated PV inverter. The proposed scheme consists of a proportional resonance (PR) controller with lag compensator (LC). This controller offers lower oscillation in output grid current and better steady state performance for the grid-tied PV inverter systems. The analytical comparison of proposed control scheme and the other control strategies are mentioned in this work. The simulation results indicate the improvements of the performance for the proposed controller in terms of reference tracking ability, total harmonic distortion (THD), and the supplied dc bus voltages of the grid-injected PV inverter systems. This proposed controller can enhance the performance of the PV systems by reducing energy consumption during load change and faulty condition
Fractal Inspired Models of Quark and Gluon Distributions and Longitudinal Structure Function FL(x, Q2) at small x
In recent years, Fractal Inspired Models of quark and gluon densities at
small x have been proposed. In this paper, we investigate longitudinal
structure function F-L (x, Q2) within this approach. We make predictions using
the QCD based approximate relation between the longitudinal structure function
and the gluon density. As the Altarelli-Martinelli equation for the
longitudinal structure function cannot be applied to Model I due to the
presence of a singularity in the Bjorken x-space we consider Model II only. The
qualitative feature of the prediction of Model II is found to be compatible
with the QCD expectation.Comment: 11 pages, 4 figures, Accepted for publication on 10-07-2010 in Indian
Journal of Physic
Changes on content, structure and surface distribution of lignin in jute fibers after laccase treatment
Effect of laccase treatment on the content, structure, and surface distribution of lignin in jute fibers were fundamentally investigated. Four percent lignin was removed from jute fibers via the laccase treatment. The residual lignin in the laccase-treated jute fibers showed increased molecular weights, which indicated polymerization between lignins on jute fibers. Meanwhile, the phenolic hydroxyl content in lignin decreased during the laccase oxidation accompanied by demethylation of methoxyl groups and generation of carbonyl groups. Due to the degradation and subsequent polymerization of lignin by laccase, the bulgy lignins on jute fiber surfaces were redistributed, which made the surface neat and glossy.This work was financially supported by the National Natural Science Foundations of China (51603087, 51673087), Program for Changjiang Scholars and Innovative Research Team in University (IRT_15R26), Fundamental Research Funds for the Central Universities (JUSRP51717A), Key R&D Program of Jiangsu Province (BE2016208), Portuguese Foundation for Science and Technology (UID/BIO/04469/2013 unit), and COMPETE 2020 (POCI-01-0145-FEDER006684).info:eu-repo/semantics/publishedVersio
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