941 research outputs found
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Simplified Production of Large Prototypes using Visible Slicing
Rapid Prototyping (RP) is a totally automatic generative manufacturing
technique based on a “divide-and-conquer” strategy called ‘slicing’. Simple
slicing used on 2.5-axis kinematics of the existing RP machines is responsible for
the staircase error. Although thinner slices will have less error, the slice thickness
has practical limits. Visible Slicing overcomes these limitations. A few visible
slices exactly represent the object. Each visible slice can be realized using a 3- axis kinematics machine from two opposite directions. Visible slicing is
implemented on Segmented Object Manufacturing (SOM) machine under
development. SOM can produce soft large prototypes faster and cheaper with
accuracy comparable to that of CNC machining.Mechanical Engineerin
Antimicrobial Activity of Aegle marmelos Against Pathogenic Organism Compared with Control Drug
The aqueous and ethanolic extracts from the leaves of Aegle marmelos traditionally used in Indian system of Medicines were screened against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis by using disc diffusion test technique. Bacillus subtilis exhibit about 22mm inhibition zone were considered resistant. The zone of inhibition of the extract was compared with the standard antibiotics such as Penicillin. The study suggests that the plant is promising development of phytomedicine for antimicrobial properties
An axiomatic approach to the non-linear theory of generalized functions and consistency of Laplace transforms
We offer an axiomatic definition of a differential algebra of generalized
functions over an algebraically closed non-Archimedean field. This algebra is
of Colombeau type in the sense that it contains a copy of the space of Schwartz
distributions. We study the uniqueness of the objects we define and the
consistency of our axioms. Next, we identify an inconsistency in the
conventional Laplace transform theory. As an application we offer a free of
contradictions alternative in the framework of our algebra of generalized
functions. The article is aimed at mathematicians, physicists and engineers who
are interested in the non-linear theory of generalized functions, but who are
not necessarily familiar with the original Colombeau theory. We assume,
however, some basic familiarity with the Schwartz theory of distributions.Comment: 23 page
Chemical speciation of nanoparticles surrounding metal-on-metal hips.
Spectromicroscopy of tissue surrounding failed CoCr metal-on-metal hip replacements detected corroded nanoscale debris in periprosthetic tissue in two chemical states, with concomitant mitochondrial damage. The majority of debris contained Cr(3+), with trace amounts of oxidised cobalt. A minority phase containing a core of metallic chromium and cobalt was also observed
DNA/RNA: Building Blocks of Life Under UV Irradiation
International audienceDuring the last 10 years, intense experimental and theoretical work has proven the existence of ultrafast nonradiative decay routes for UV-excited monomeric nucleic acid bases, accounting for their high photostability. This mechanism has been explained by the occurrence of easily accessible conical intersections connecting the first excited ππ* state with the ground state. However, recent studies of substituent and solvent effects indicate that the situation is more complicated than what was initially thought, notably by the presence of dark excited states. Moreover, the actual shape of the excited-state potential energy surface may induce nonexponential dynamics. Further efforts are needed in order to clarify how various environmental factors affect the structural and dynamical aspects of the nucleic acid base excited states
Influence of Substrates on the Surface Characteristics and Membrane Proteome of Fibrobacter succinogenes S85
Although Fibrobacter succinogenes S85 is one of the most proficient cellulose degrading bacteria among all mesophilic organisms in the rumen of herbivores, the molecular mechanism behind cellulose degradation by this bacterium is not fully elucidated. Previous studies have indicated that cell surface proteins might play a role in adhesion to and subsequent degradation of cellulose in this bacterium. It has also been suggested that cellulose degradation machinery on the surface may be selectively expressed in response to the presence of cellulose. Based on the genome sequence, several models of cellulose degradation have been suggested. The aim of this study is to evaluate the role of the cell envelope proteins in adhesion to cellulose and to gain a better understanding of the subsequent cellulose degradation mechanism in this bacterium. Comparative analysis of the surface (exposed outer membrane) chemistry of the cells grown in glucose, acid-swollen cellulose and microcrystalline cellulose using physico-chemical characterisation techniques such as electrophoretic mobility analysis, microbial adhesion to hydrocarbons assay and Fourier transform infra-red spectroscopy, suggest that adhesion to cellulose is a consequence of an increase in protein display and a concomitant reduction in the cell surface polysaccharides in the presence of cellulose. In order to gain further understanding of the molecular mechanism of cellulose degradation in this bacterium, the cell envelope-associated proteins were enriched using affinity purification and identified by tandem mass spectrometry. In total, 185 cell envelope-associated proteins were confidently identified. Of these, 25 proteins are predicted to be involved in cellulose adhesion and degradation, and 43 proteins are involved in solute transport and energy generation. Our results supports the model that cellulose degradation in F. succinogenes occurs at the outer membrane with active transport of cellodextrins across for further metabolism of cellodextrins to glucose in the periplasmic space and inner cytoplasmic membrane
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Cysteamine inhibits lysosomal oxidation of low density lipoprotein in human macrophages and reduces atherosclerosis in mice
Background and aims: We have shown previously that low density lipoprotein (LDL) aggregated by vortexing is internalised by macrophages and oxidised by iron in lysosomes to form the advanced lipid/protein oxidation product ceroid. We have now used sphingomyelinase-aggregated LDL, a more pathophysiological form of aggregated LDL, to study lysosomal oxidation of LDL and its inhibition by antioxidants, including cysteamine (2-aminoethanethiol) which concentrates in lysosomes by several orders of magnitude. We have also investigated the effect of cysteamine on atherosclerosis in mice.
Methods: LDL was incubated with sphingomyelinase, which increased its average particle diameter from 26 to 170 nm, and was then incubated for up to 7 days with human monocyte-derived macrophages. LDL receptor-deficient mice were fed a Western diet (19-22 per group) and some given cysteamine in their drinking water at a dose equivalent to that used in cystinosis patients. The extent of atherosclerosis in the aortic root and the rest of the aorta was measured.
Results: Confocal microscopy revealed lipid accumulation in lysosomes in the cultured macrophages. Large amounts of ceroid were produced, which colocalised with the lysosomal marker LAMP2. The antioxidants cysteamine, butylated hydroxytoluene, amifostine and its active metabolite WR-1065, inhibited the production of ceroid. Cysteamine at concentrations well below those expected to be present in lysosomes inhibited the oxidation of LDL by iron ions at lysosomal pH (pH 4.5) for prolonged periods. Finally, we showed that the extent of atherosclerotic lesions in the aortic root and arch of mice was significantly reduced by cysteamine.
Conclusions: These results support our hypothesis that lysosomal oxidation of LDL is important in atherosclerosis and hence antioxidant drugs that concentrate in lysosomes might provide a novel therapy for this disease
The Satellite Luminosity Function of M101 into the Ultra-Faint Dwarf Galaxy Regime
We have obtained deep Hubble Space Telescope (HST) imaging of four faint and
ultra-faint dwarf galaxy candidates in the vicinity of M101 - Dw21, Dw22, Dw23
and Dw35, originally discovered by Bennet et al. (2017). Previous distance
estimates using the surface brightness fluctuation technique have suggested
that these four dwarf candidates are the only remaining viable M101 satellites
identified in ground based imaging out to the virial radius of M101 (D~250
kpc). Advanced Camera for Surveys imaging of all four dwarf candidates shows no
associated resolved stellar populations, indicating that they are thus
background galaxies. We confirm this by generating simulated HST color
magnitude diagrams of similar brightness dwarfs at the distance of M101. Our
targets would have displayed clear, resolved red giant branches with dozens of
stars if they had been associated with M101. With this information, we
construct a satellite luminosity function for M101, which is 90% complete to
M_V=-7.7 mag and 50% complete to M_V=-7.4 mag, that extends into the
ultra-faint dwarf galaxy regime. The M101 system is remarkably poor in
satellites in comparison to the Milky Way and M31, with only eight satellites
down to an absolute magnitude of M_V=-7.7 mag, compared to the 14 and 26 seen
in the Milky Way and M31, respectively. Further observations of Milky Way
analogs are needed to understand the halo-to-halo scatter in their faint
satellite systems, and connect them with expectations from cosmological
simulations.Comment: 9 Pages, 3 Figures, 1 Table, Accepted by ApJ
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Structural Changes in Irrigation Vis-à-vis Cropping Pattern in Andhra Pradesh, India: An Economic Analysis
The inherent dynamism within a system leads to structural changes of that system. Over the past, the structural changes that are occurring in the world economies are affecting the subsystems one or another way. The development of a nation like India reflects from the development of its states. The current study focuses on the structural shifts within primary sector of Andhra Pradesh (includes Telangana State’s data) more precisely, economic linkages between irrigation and between the dynamic changes in cropping pattern. It also explores the implications of dynamic changes happened in state’s agriculture after green revolution. The shifts from period 1970 – 2020 are studied using secondary data. Growth rate and conventional analyses (percentages and averages) are used to study the effects of shifts in irrigation on cropping pattern of the state. The results exhibit, declining ecofriendly surface water irrigation systems (tanks) by twofold compensated with increased extraction of groundwater resources by fivefold. As a consequence, decline in net cropped area and cropping pattern shifts adopting mono-cropping or double cropping under rice as major crop followed by cash crops or pulse crops under groundwater and canal systems of irrigation aroused. While coarse cereals have lost prominence, cash crops like chilly (93 per cent) have gained importance under irrigation. The prominence of livestock sector in the state can be realized as net irrigated area under fodder crops improved to 50.61 per cent over the decades. Overall improvement in net irrigated area with canal and groundwater systems of irrigation is current scenario of the state. Pressurized irrigation technologies should be promoted to maintain sustainability of tank irrigation structures. Cropping patterns including coarse cereals should be adopted for maintaining nutritional security. Adoption of reclamation measures to attain ecological balance between groundwater and surface water irrigation sources
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