227 research outputs found
Design And Hydraulic Performance Of A Novel Hydraulic Ram Pump
The automatic hydraulic ram pump (hydram) is a unique device that utilizes energy from a falling quantity of water as the driving power to pump some of the water to a head much higher than the source. The hydraulic ram is structurally simple, consisting of only two moving parts: the waste valve and the delivery (check) valve. There is also an air chamber with an air or snifter valve. With a continuous flow of water, the hydram will operate automatically and continuously with no other external energy. Hydrams are suitable for small-scale water supply schemes supplying farm- houses and isolated settlements as well as in rural situations in developing countries. The authors develop a novel hydram that contains the three innovations. A new structure and shape of hydram is designed to greatly reduce its size and weight, but has the similar hydraulic performance to the conventional hydrams. Based on hard metal seal, the elastic seal is added for the waste valve and the delivery valve, respectively. The hard metal seal primarily bears the impact of the moving valve disc while the elastic seal is responsible for sealing and reducing noise from the impact of the moving valve disc against the hard metal seal. A device, consisting of a valve and a short pipe that connects the air chamber to the lifting pipe, is added to automatically adjust the gas volume upper the air chamber, so as to keep the hydram operating in a state of high efficiency. Finally, the hydraulic performance of the novel hydram is measured by the model tests
Effect of Mild Heating Assisted Alkaline pH Shift Treatment on the Structural and Functional Properties of Porcine Liver Protein
In this study, a combined method of physical and chemical modification was used to improve the functional characteristics of porcine liver protein (PLP). PLP was modified by mild heating assisted alkaline pH shift treatment. The hydration properties, surface properties, particle size distribution, denaturation degree and molecular structure of modified PLP were measured. The results showed that heat treatment combined with a large shift in pH toward the alkaline side significantly increased the solubility and emulsifying activity of PLP, reduced the particle size while resulting in uniform size distribution, increased the absolute value of zeta potential, and decreased the free sulfhydryl content, changed the primary, secondary and tertiary structures, and increased the surface hydrophobicity. The combined treatment was superior to either treatment alone. In terms of improvements in the hydration and surface properties of PLP, heating at 50 ℃ combined with pH shift toward pH 11 was the best modification condition for PLP
Climate change and its influence on the Karst groundwater recharge in the Jinci Spring Region, Northern China
Due to climate change and human activities over the last fifty years, the spring flow
volume of karst groundwater has sharply diminished in China. Climate change is one of the critical
factors that initiates a series of karst hydrogeologic and water ecological environmental problems,
because the precipitation shows a decreasing trend while the temperature shows an increasing trend.
The Jinci Spring is one of the largest, most famous springs in northern China. This study employed
data from the Taiyuan Meteorological Station and ten precipitation stations in and around the Jinci
Spring region as well as the runoff data gathered from two hydrological monitoring stations during
1960-2012. The sliding average method and the Mann-Kendall test were used to analyze the variation
tendency of precipitation, temperature, and land evaporation in this area. Finally, the following
were calculated: the varying pattern of the karst groundwater recharge amount and the response
of the recharge amount to precipitation, land evaporation, and river runoff by quantitative analysis.
The results indicated that the precipitation and land evaporation amount decreased at first and then
subsequently increased. Likewise, the variation trend of the karst groundwater recharge amount
in the spring region was roughly consistent with the precipitation variation pattern. In contrast,
the temperature displayed an increasing trend. The climate change resulted in a reduction of the
karst groundwater recharge amount, and it had the greatest influence in the 1990s, which caused the
karst groundwater recharge amount to decrease 26.75 mm as compared to that of the 1960s (about
39.68% lower than that of the 1960s). The Jinci Spring had zero flow during this period. The reduction
in precipitation was one of main factors that caused the cutoff of the Jinci Spring.IS
Replication Stress Induces Micronuclei Comprising of Aggregated DNA Double-Strand Breaks
BACKGROUND: Micronuclei (MN) in mammalian cells serve as a reliable biomarker of genomic instability and genotoxic exposure. Elevation of MN is commonly observed in cells bearing intrinsic genomic instability and in normal cells exposed to genotoxic agents. DNA double-strand breaks are marked by phosphorylation of H2AX at serine 139 (γ-H2AX). One subclass of MN contains massive and uniform γ-H2AX signals. This study tested whether this subclass of MN can be induced by replication stress. PRINCIPAL FINDINGS: We observed that a large proportion of MN, from 20% to nearly 50%, showed uniform staining by antibodies against γ-H2AX, a marker of DNA double-strand breaks (DSBs). Such micronuclei were designated as MN-γ-H2AX (+). We showed that such MN can be induced by chemicals that are known to cause DNA replication stress and S phase arrest. Hydroxyurea, aphidicolin and thymidine could all significantly induce MN-γ-H2AX (+), which were formed during S phase and appeared to be derived from aggregation of DSBs. MN-γ-H2AX (-), MN that were devoid of uniform γ-H2AX signals, were induced to a lesser extent in terms of fold change. Paclitaxel, which inhibits the disassembly of microtubules, only induced MN-γ-H2AX (-). The frequency of MN-γ-H2AX (+), but not that of MN-γ-H2AX (-), was also significantly increased in cells that experience S phase prolongation due to depletion of cell cycle regulator CUL4B. Depletion of replication protein A1 (RPA1) by RNA interference resulted in an elevation of both MN-γ-H2AX (+) and MN-γ-H2AX (-). CONCLUSIONS/SIGNIFICANCE: A subclass of MN, MN-γ-H2AX (+), can be preferentially induced by replication stress. Classification of MN according to their γ-H2AX status may provide a more refined evaluation of intrinsic genomic instabilities and the various environmental genotoxicants
Chirality manipulation of ultrafast phase switchings in a correlated CDW-Weyl semimetal
A recently emerging concept for quantum phase discovery is the controlled
gapping of linear band crossings in topological semimetals. For example,
achieving topological superconducting and charge-density-wave (CDW) gapping
could introduce Majorana zero modes and axion electrodynamics, respectively.
Light engineering of correlation gaps in topological materials provides a new
avenue of achieving exotic topological phases inaccessible by conventional
tuning methods such as doping and straining. Here we demonstrate a light
control of correlation gaps and ultrafast phase switchings in a model CDW and
polaron insulator (TaSe)I recently predicted to be an axion insulator.
Our ultrafast terahertz photocurrent spectroscopy reveals a two-step,
non-thermal melting of polarons and electronic CDW gap via studying the fluence
dependence of a {\em longitudinal} circular photogalvanic current. The
helicity-dependent photocurrent observed along the propagation of light reveals
continuous ultrafast switchings from the polaronic state, to the CDW (axion)
phase, and finally to a hidden Weyl phase as the pump fluence increases. Other
distinguishing features corroborating with the light-induced switchings
include: mode-selective coupling of coherent phonons to polaron and CDW
modulation, and the emergence of a {\em non-thermal} chiral photocurrent above
pump threshold of CDW-related phonons. The ultrafast chirality control of
correlated topological states revealed here is important to realize axion
electrodynamics and quantum computing.Comment: 9 pages, 4 figure
Symmetric Hyperbolic System in the Self-dual Teleparallel Gravity
In order to discuss the well-posed initial value formulation of the
teleparallel gravity and apply it to numerical relativity a symmetric
hyperbolic system in the self-dual teleparallel gravity which is equivalent to
the Ashtekar formulation is posed. This system is different from the ones in
other works by that the reality condition of the spatial metric is included in
the symmetric hyperbolicity and then is no longer an independent condition. In
addition the constraint equations of this system are rather simpler than the
ones in other works.Comment: 8 pages, no figure
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