2,150,151 research outputs found
CR submanifolds in Kaehler and nearly Kaehler manifolds
Get PDFA review of the study of CR, submanifolds within Kaehler and nearly Kaehler manifolds, and the properties of such manifolds with respect submanifold theory in differential geometry. The study in such a fashion is relatively young, most being carried out within the past thirty years. We consider CR submanifolds as a generalization of complex and real submanifolds, with the tangent bundle decomposing into real and complex parts. We demonstrate that the CR structure has strong consequences, and is heavily dependant on the properties of the ambient manifold. The integrability of the real and complex parts is examined in various spaces, and we consider the existence of CR submanifolds with product, warped product, and foliate structure. The relationship governing the curvatures of the ambient manifold, the CR submanifold and leaves of the complex and real distributions are all considered. We consider the general cases of complex, almost complex, Kaehler and nearly Kaehler manifolds. Further detail is included for the specific manifolds of flat complex space, complex hyperbolic space, complex projective space and the 6-sphere.As an example of the applications of CR structure we include some work on the index of paths, and some topological consequences. Examples of CR submanifolds are generated for the 6-sphere, and the properties of these submanifolds are considered, including the minimality and the second fundamental form. We include details of possible further study, and suggestions for how techniques used might be fruitfully employed elsewhere
Phytoextraction of Cr(VI) from soil using Portulaca oleracea
No full textCr(VI) represents an environmental challenge in both soil and water as it is soluble and bioavailable over a wide range of pH. In previous investigations, Portulaca oleracea (a plant local to the United Arab Emirates (UAE)) demonstrated particular ability for the phytoextraction of Cr(VI) from calcareous soil of the UAE. In this publication, the results of the evaluation of P. oleracea phytoextraction of Cr(VI) from UAE soil at higher concentrations are reported. P. oleracea was exposed to nine different concentrations of Cr(VI) in soil from 0 to 400 mg kg−1. The uptake of Cr(VI) increased as its concentration in soil increased between 50 and 400 mg kg−1, with the most efficient removal in the range from 150 to 200 mg kg−1. The total chromium concentrations exceeded 4600 mg kg−1 in roots and 1400 mg kg−1 in stems, confirming the role of P. oleracea as an effective Cr(VI) accumulator. More than 95% of the accumulated Cr(VI) was reduced to the less toxic Cr(III) within the plant
Effects of the alloy composition on phase constitution and properties of laser deposited Ni-Cr-B-Si coatings
Get PDFThree Ni-Cr-B-Si hardfacing alloy powders with different Cr contents and Si to B ratios were deposited at cladding speeds of 5-40 mm/s on steel substrate using laser beam and the alloy composition-phase formation-properties relationships in the deposits were studied using several experimental techniques. Two general groups of compositions could be defined in this alloy system; the high-alloy grades characterized by numerous Cr boride precipitates, a low Si/B ratio and substantial Ni-B-Si eutectics, and the low-alloy grades with very little Cr boride precipitates, a high Si/B ratio and limited amounts of interdendritic eutectics. The findings confirmed that phase formation of Ni-Cr-B-Si laser deposited coatings primarily depends on the Cr content and Si/B ratio with the former controlling the amount of Cr-rich precipitates and the latter influencing the nature of the eutectic structures. In addition, it is shown that both Cr-rich precipitates and eutectic structures contribute to the functional properties of the coatings such as hardness and cracking susceptibility. The correlation between phase constitutions produced by different compositions and the hardness/cracking tendency is established and discussed.
Protein expression on Cr resistant microorganism using electrophoresis method
Get PDFAbstrak. Fatmawati U, Suranto, Sajidan. 2009. Ekspresi protein pada mikroorganisme resisten Cr dengan metode elektroforesis.
Nusantara Bioscience 1: 31-37. Krom heksavalen (Cr(VI)) dikenal sebagai logam berat beracun, sehingga perlu direduksi menjadi
Cr(III) yang lebih rendah toksisitasnya. Pseudomonas aeruginosa, Pseudomonas putida, Klebsiella pneumoniae, Pantoea sp. dan
Saccharomyces cerevisiae adalah mikroorganisme resisten dan mampu mereduksi Cr(VI). Tujuan penelitian ini adalah mengetahui
kemampuan mikroorganisme dalam mengurangi Cr(VI) dan mengetahui pola pita protein antara mikroorganisme resisten Cr(VI) dan
mikroorganisme tidak resisten yang diinokulasi pada medium kaldu LB. SDS-PAGE digunakan untuk mengetahui ekspresi protein,
sementara konsentrasi Cr(VI) diidentifikasi dengan metode 1,5 difenilkarbazid. Data kuantitatif dianalisis dengan ANAVA dua faktorial
dilanjutkan dengan uji jarak berganda Duncan pada taraf 1%. Data kualitatif yaitu ekspresi protein dianalisis dengan mobilitas relatif
(Rf). Hasil penelitian menunjukkan bahwa kemampuan mikroorganisme dalam mereduksi Cr(VI) pada konsentrasi awal 0.5 ppm, 1 ppm,
5 ppm dan 10 ppm berbeda-beda, persentase rata-rata kemampuan masing-masing mikroorganisme dalam mereduksi Cr(VI) adalah: P.
putida (65%) > S. cerevisiae (64,45%) > P. aeruginosa (60,73%) > Pantoea sp. (50,22%) > K. pneumoniae (47,82%) > tanpa
mikroorganisme (34,25%). Penambahan mikroorganisme secara nyata mempengaruhi reduksi Cr(VI). SDS-PAGE menunjukkan bahwa
ekspresi protein antara mikroorganisme resisten dan tidak resisten tidak berbeda, tetapi mikroorganisme resisten memiliki lebih banyak
protein (pita protein lebih tebal).
Kata kunci: logam berat Cr, mikroorganisme, protein, elektroforesis
Micro-abrasion–corrosion of a Co–Cr/UHMWPE couple in Ringer's solution : an approach to construction of mechanism and synergism maps for application to bio-implants
No full textIn studies of tribo-corrosion, the degradation of bio-materials has become of increasing research interest in recent years. This is because, in many cases, the interactions of the tribological and corrosion component in biological environments are not well understood. Moreover, the wide range of variables involved in the tribo-corrosion process, and the variety of materials used in such conditions, means that there are few systematic studies where materials and operating conditions are optimized. In the total replacement of hip joints, the Co-Cr/UHMWPE couple has been used widely. However, the application of any replacement joint for biological conditions will depend on many factors including the activity of the patient and the overall load imposed on the artificial joint. This means evaluation of the tribo-corrosion behaviour over a multi parameter space is important in order to assess the degradation possible for many patient/activity and body mass categories.In this work, the performance of a Co-Cr/UHMWPE couple was evaluated in Ringer's solution in a tribological situation where micron size particles particles were entrained in the contact - micro-abrasion-corrosion. The effects of applied load and potential were investigated in the study. Micro-abrasion-corrosion maps were constructed for the material indicating the mechanism of degradation, the extent of wastage and of synergy/antagonism involved in the tribo-corrosion interaction
carnotresearch/cr-nimble: CR-Nimble v0.2.4
No full textAdded
Digital signal processing utilities moved from cr-sparse to cr-nimble
Moved discrete number related functions from cr-sparse.
Some sparse vector and matrix processing functionality moved from cr-sparse.
Removed
Unnecessary __init__.py files removed.
Notes
Jax 0.3.14 compatibility
Aligning version numbering across sister projects
Electron Microscopy Characterization of Ni-Cr-B-Si-C Laser Deposited Coatings
Get PDFDuring laser deposition of Ni-Cr-B-Si-C alloys with high amounts of Cr and B, various microstructures and phases can be generated from the same chemical composition that results in heterogeneous properties in the clad layer. In this study, the microstructure and phase constitution of a high-alloy Ni-Cr-B-Si-C coating deposited by laser cladding were analyzed by a combination of several microscopy characterization techniques including scanning electron microscopy in secondary and backscatter imaging modes, energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The combination of EDS and EBSD allowed unequivocal identification of micron-sized precipitates as polycrystalline orthorhombic CrB, single crystal tetragonal Cr5B3, and single crystal hexagonal Cr7C3. In addition, TEM characterization showed various equilibrium and metastable Ni-B, Ni-Si, and Ni-Si-B eutectic products in the alloy matrix. The findings of this study can be used to explain the phase formation reactions and to tune the microstructure of Ni-Cr-B-Si-C coatings to obtain the desired properties.
CR-Cross
No full textCR-Cross: A Novel Approach for Cross Domain Coral Recognitions with Reject Options</p
Cr(VI) and Cr(III)-Based Conversion Coatings on Zinc
No full textWith the aims of understanding the protective mechanism of chromate conversion coatings and developing alternatives to chromate treatments, the physical natures and corrosion properties of Cr(VI) and Cr(III) treated zinc have been investigated in this work. The Cr(VI) treatments were carried out in dichromate and sulfuric acid solution with different dipping times. The Cr(III) treatments were carried out in two commercial solutions (A and B). The thickness of the coatings was measured using ellipsometry. The morphologies and the compositions of the treated zinc have been studied by means of SEM, AFM, AES, FTIR and XPS. The drying temperature influence on the corrosion performance of the Cr(VI)âtreated zinc has been investigated. The Volta potential in treated and untreated areas has been measured using scanning Kelvin probe (SKP) and SKPFM. The corrosion behavior of the Cr(VI) and Cr(III) treated zinc has been investigated using polarization, electrochemical impedance measurements (EIS), and salt spray tests. Both Cr(VI) and Cr(III) species were detected by XPS in the outermost layer of the Cr(VI) coatings, while no Cr(VI) species was found in the Cr(III) coatings. AES depth profile results show that chromium oxides are the main components in the Cr(VI) coatings. Zinc oxide is mainly located at the chromium oxides / zinc interface. The Cr(III) coating is a mixture of chromium oxides and zinc oxide. Both the Cr(VI) and the Cr(III) treatments can supply corrosion protection to zinc. The corrosion resistance of the Cr(III)-B coating is greater than that of the Cr(III)-A coating. However, the inhibition of the corrosion of zinc by Cr(VI) coating is more effective than by the Cr(III) coatings. The inhibition of the corrosion of zinc by the Cr(VI) and the Cr(III) treatments is discussed, and future research topics are suggested.Mechanical, Maritime and Materials Engineerin
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