Flexural, impact resistance, tensile, and sound absorption properties of composites from cornhusk fiber (CHF) and PP have been investigated. The effect of holding temperature, CHF length, CHF concentration, and enzyme treatment of CHF on mechanical properties and the effect of the latter two on sound absorption have been studied. Compared with jute/PP composites, CHF/PP composites have similar impact resistance, 33% higher flexural strength, 71% lower flexural modulus, 43% higher tensile strength, 54% lower tensile modulus, and slightly higher noise reduction coefficient. Enzyme treatment of CHF results in increased mechanical and sound absorption properties.
In this paper, development of large-area planar avalanche photodiodes (APDs) and monolithic APD arrays for X-ray and scintillation detection is discussed. Single APDs with areas as large as 10 cm2 have been fabricated and tested with a CsI(Tl) scintillator (3.8 cm diameter, 2.5 cm height). The resolution of the 662 keV photopeak has been measured to be 9% (FWHM). The X-ray detection performance, gain, and noise of these large APDs have been characterized. Multielement APD arrays have also been fabricated in various formats, such as 4×4 to 14×14 elements (2 mm pixels), and the uniformity of gain, noise, and sensitivity has been evaluated for 4×4 arrays using an 55Fe source. Timing properties have been measured. Packaging issues related to the APD arrays are discussed 相似文献
This paper proposes the development and experimental tests of a self-paced asynchronous brain-computer interfacing (BCI) system that detects movement related cortical potentials (MRCPs) produced during motor imagination of ankle dorsiflexion and triggers peripheral electrical stimulations timed with the occurrence of MRCPs to induce corticospinal plasticity. MRCPs were detected online from EEG signals in eight healthy subjects with a true positive rate (TPR) of 67.15 ± 7.87% and false positive rate (FPR) of 22.05 ±9.07%. The excitability of the cortical projection to the target muscle (tibialis anterior) was assessed before and after the intervention through motor evoked potentials (MEP) using transcranial magnetic stimulation (TMS). The peak of the evoked potential significantly (P=0.02) increased after the BCI intervention by 53 ± 43% (relative to preintervention measure), although the spinal excitability (tested by stretch reflexes) did not change. These results demonstrate for the first time that it is possible to alter the corticospinal projections to the tibialis anterior muscle by using an asynchronous BCI system based on online motor imagination that triggered peripheral stimulation. This type of repetitive proprioceptive feedback training based on self-generated brain signal decoding may be a requirement for purposeful skill acquisition in intact humans and in the rehabilitation of persons with brain damage. 相似文献
In this study, plants belonging to family Solanaceae growing in Western Himalaya region have been observed palynologically under Light Microscope and Scanning electron microscope. Present investigation comprises of 10 genera and 23 species, namely, Atropa acuminata, Capsicum decoraticus, Capsicum frutescens, Cestrum aurantiacum, Cestrum diurnum, Cestrum nocturnum, Datura alba, Datura innoxia, Datura stramonium, Hyoscymus niger, Lycopersicon esculentum, Nicotiana rustica, Nicotiana tabacum, Petunia alba, Petunia hybrida, Solanum erianthum, Solanum melongena, Solanum miniatum, Solanum pseudocapsicum, Solanum surratense, Solanum tuberosum, Withania coagulans, Withania somnifera. Solanaceae is a eurypalynous family. Grains are usually Tricolporate and Tetracolporate, radially symmetrical, isopolar, prolate‐spheroidal to oblate‐spheroidal to oblate‐spheroidal to subprolate to per prolate or suboblate to oblate, size range: 8.55–72 μm, amb circular, semi‐angular or subangular, aperture drop‐type, labrum common‐type, exine usually 2 μm thick, nexine 1–1.5 μm thick. Tectum usually psilate, sexine reticulate, granulate or striato‐reticulate, with obscure pattern, sexine 1–2 μm thick, nexine 1–1.5 μm thick, and intine 0.5–1 μm thick. Most striking variation has been found in the shape class, aperture‐type, and tectal surface. Based on these characters, taxonomic keys have been made for correct identification of members in Solanaceae. However, the grains of this family are usually tricolporate and have direct relationship with certain members of the family Scrophulariaceae. Palyno‐morphological characters of family Solanaceae have been studied for the first time in Western Himalayan region of Pakistan. These palyno‐morphological characters are significant for identification of the members of family Solanaceae. 相似文献
In this study, egg proteins are used as a nitrogen source for the synthesis of nitrogen-rich carbonaceous material through hydrothermal carbonization (HTC) for the electrochemical energy storage application. The composite of activated carbon with egg-derived protein (AC/EDP) is prepared by mixing untreated egg proteins in the aqueous dispersion of activated carbon, followed by HTC at 220 °C for 12 h in a Teflon-lined autoclave. The resultant composite is then directed to chemical activation with KOH and thermal activation at a temperature ranging from 500 to 700 °C. The nitrogen-doped activated carbon exhibited a microporous and mesoporous structure with a high specific surface area of 1660 m2 g?1, confirmed through BET analysis. The composite morphology was analyzed through scanning and high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy indicates the presence of a considerable amount of pyrrolic, pyridinic, and quaternary nitrogen in AC/EDP, which improved the electrochemical performance. The composite activated at 700 °C exhibited the highest capacitance of 263 F g?1 at a current density of 0.2 A g?1. The highest energy density and power density values are 32 Wh kg?1 and 7920 W kg?1, respectively. The AC/EDP exhibited high cyclic stability, and the capacitance retention observed after 10,000 cycles is 98%.
Chloramines in drinking water may form N-nitrosodimethylamine (NDMA). Various primary disinfectants can deactivate NDMA precursors prior to chloramination. However, they promote the formation of other byproducts. This study compared the reduction in NDMA formation due to chlorine, ozone, chlorine dioxide, and UV over oxidant exposures relevant to Giardia control coupled with postchloramination under conditions relevant to drinking water practice. Ten waters impacted by treated wastewater, poly(diallyldimethylammonium chloride) (polyDADMAC) polymer, or anion exchange resin were examined. Ozone reduced NDMA formation by 50% at exposures as low as 0.4 mg×min/L. A similar reduction in NDMA formation by chlorination required ~60 mg×min/L exposure. However, for some waters, chlorination actually increased NDMA formation at lower exposures. Chlorine dioxide typically had limited efficacy regarding NDMA precursor destruction; moreover, it increased NDMA formation in some cases. UV decreased NDMA formation by ~30% at fluences >500 mJ/cm(2), levels relevant to advanced oxidation. For the selected pretreatment oxidant exposures, concentrations of regulated trihalomethanes, haloacetic acids, bromate, and chlorite typically remained below current regulatory levels. Chloropicrin and trichloroacetaldehyde formation were increased by preozonation or medium pressure UV followed by postchloramination. Among preoxidants, ozone achieved the greatest reduction in NDMA formation at the lowest oxidant exposure associated with each disinfectant. Accordingly, preozonation may inhibit NDMA formation with minimal risk of promotion of other byproducts. Bromide >500 μg/L generally increased NDMA formation during chloramination. Higher temperatures increased NDMA precursor destruction by preoxidants but also increased NDMA formation during postchloramination. The net effect of these opposing trends on NDMA formation was water-specific. 相似文献
A general form fracture resistance curve, R-curve, is presented in this paper based upon the energy criterion of crack propagation determined by strain energy release rate. The R-curve is derived, in general, as the envelope of a set of strain energy release rate curves of same size and geometry but with different initial crack lengths. 相似文献
To develop highly efficient electrochemical catalysts for N2 fixation is important to sustainable ambient NH3 production through the N2 reduction reaction (NRR). Herein, we demonstrate the development of vanadium phosphide nanoparticle on V foil as a high-efficiency and stable catalyst for ambient NH3 production with excellent selectivity. The high Faradaic efficiency of 22% with a large NH3 yield of 8.35 × 10−11 mol·s−1·cm−2 was obtained at 0 V vs. the reversible hydrogen electrode in acid solution, superior to all previously studied V-based NRR catalysts. Density functional theory calculations are also utilized to have an insight into the catalytic mechanism.
Starting from one undefined cheese smear consortium exhibiting anti-listerial activity (signal) at 15 °C, 50 yeasts and 39 bacteria were identified by partial rDNA sequencing. Construction of microbial communities was done either by addition or by erosion approach with the aim to obtain minimal communities having similar signal to that of the initial smear. The signal of these microbial communities was monitored in cheese microcosm for 14 days under ripening conditions. In the addition scheme, strains having significant signals were mixed step by step. Five-member communities, obtained by addition of a Gram negative bacterium to two yeasts and two Gram positive bacteria, enhanced the signal dramatically contrary to six-member communities including two Gram negative bacteria. In the erosion approach, a progressive reduction of 89 initial strains was performed. While intermediate communities (89, 44 and 22 members) exhibited a lower signal than initial smear consortium, eleven- and six-member communities gave a signal almost as efficient. It was noteworthy that the final minimal model communities obtained by erosion and addition approaches both had anti-listerial activity while consisting of different strains. In conclusion, some minimal model communities can have higher anti-listerial effectiveness than individual strains or the initial 89 micro-organisms from smear. Thus, microbial interactions are involved in the production and modulation of anti-listerial signals in cheese surface communities. 相似文献