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Search Results: 1 - 10 of 540421 matches for " L. M.; "
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On the Dark Matter’s Halo Theoretical Description  [PDF]
L. M. L. M. Chechin
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.35052
Abstract: We argued that the standard field scalar potential couldn’t be widely used for getting the adequate galaxies’ curve lines and determining the profiles of dark matter their halo. For discovering the global properties of scalar fields that can describe the observable characteristics of dark matter on the cosmological space and time scales, we propose the simplest form of central symmetric potential celestial-mechanical type, i.e. U(φ) = –μ/φ. It was shown that this potential allows get rather satisfactorily dark matter profiles and rotational curves lines for dwarf galaxies. The good agreement with some previous results, based on the N-body simulation method, was pointed out. A new possibility of dwarf galaxies’ masses estimation was given, also.
Causality and Reversibility in Irreversible Time:Book Review  [PDF]
M. L. Arushanov
Journal of Quantum Information Science (JQIS) , 2012, DOI: 10.4236/jqis.2012.21001
Abstract: From classical point of view the full description of a system is the sum of its parties descriptions. Quantum mechanics introduced essential correction in the classical view: the measurable properties of a particle ensemble can exceed the properties sum of its particles. It is impossible to describe such entangled states by the known local field equation. Now nonlocal quantum correlations are well known, they underlie quantum information science and have the practical applications already. On the other hand in macro-physics, in particular, in astrophysics and geophysics a lot of facts about distant dissipative processes correlations (including violating classical causality) not reducible to electromagnetic and gravitation interactions have been collected. These correlations could be explained by their nonlocal nature. Although thermo- dynamic limit now is already a subject of entanglement research, the mentioned large-scale processes have remained out of scope of quantum information. The book “Causality and Reversibility in Irreversible Time” by S. M. Korotaev is the first attempt to fill this gap.
Cadmium Removal from Aqueous Solution by a Tunisian Smectitic Natural and Activated Clay: Thermodynamic Study  [PDF]
L . Khalfa, M. Bagane
Journal of Encapsulation and Adsorption Sciences (JEAS) , 2011, DOI: 10.4236/jeas.2011.14009
Abstract: The removal of heavy metals from industrial waste streams has become one of the most important applications in wastewater treatment in terms of protecting public health and environment. The recovery of metals present in the industrial effluents by adsorption onto natural materials constitutes a technological option increasingly studied throughout the world. However, the implementation of such process on an industrial scale requires the use of adsorbents easily available and inexpensive. Clay in these two forms natural and activated answers very well to these two requirements. The present research aimed the study of the capacity of fixing of cadmium present in aqueous solution, by two types of clay: natural and activated. The adsorption capacity of adsorbent was investigated using batch experiments. The influence of pH, temperature and adsorbent dose were investigated and the experimental data obtained were evaluated and fitted using adsorbent equilibrium isotherms. Adsorption isotherms of cadmium onto natural and activated clay were determined and correlated with common isotherm equations such as the Langmuir and Freundlich models. The Langmuir model agrees very well with experimental data. The thermodynamic parameters obtained indicated that the adsorption of cadmium ions onto natural clay was a spontaneous and an endothermic process.
On the Modern Status of the Universe Rotation Problem  [PDF]
L. M. Chechin
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.48A012

The brief modern review of the Universe rotation problem is given. Also it was argued the vacuum concept of the Universe rotation, found the galactic coordinates of the Universe rotation axis, based theoretically the concept of the decaleration parameter anisotropy.

An Application of Principal Agent Theory to Contractual Hiring Arrangements within Public Sector Organizations  [PDF]
Charlene M. L. Roach
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.61004
Abstract: This paper critically examines the application of principal agent theory to contractual hiring arrangements of employees in public sector organizations as a contemporary alternative recruitment strategy. Globally, developed and developing nations within the public sector are seeking ways where they can reduce public expenditure and debt while at the same time attempting to increase productivity and efficiency gains by using cost containment initiatives. Thus, private sector methods of outsourcing and contracting are identified as more economically feasible strategies given global recessions and other budgetary constraints within these public agencies. Hence, public management and administration scholars have alluded to the catchy phrase of “doing more with less” (see [1]). Thus, the paper from a theoretically exploratory perspective analyzes how principal agent theory can be applied to the hiring of contingent employees within this sector and the agency problems that may likely arise as a result of these arrangements and their probable economic implications for the said sector.
Critical Parameters and Magnetocaloric Effect of the La5/8Ca3/8Mn0.9750Pd0.025O3 Compound  [PDF]
L. V. Bau, N. M. An
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.512086
Abstract: The La5/8Ca3/8Mn0.9750Pd0.025O3 compound was studied using DC magnetization measurements. The data were analyzed in the paramagnetic-ferromagnetic phase transition region by the Arrott plot method. The results show the Curie temperature TC ~ 247.8 K and the critical exponents of b = 0.48633, g = 1.18623 and d = 3.431682. The values of the critical exponents are between the mean- field theory and 3D Ising model. The magnetocaloric value is ~5 J/kgK, extracted from the M(H) curves.
Elevated Carbon Dioxide and Soil Moisture on Early Growth Response of Soybean  [PDF]
M. Madhu, Jerry L. Hatfield
Agricultural Sciences (AS) , 2015, DOI: 10.4236/as.2015.62027

Interactions between elevated [CO2] and soil water availability have the potential impact on crops and future food security of the world. The study was conducted to investigate vegetative growth response of soybeans under two [CO2] (380 and 800 μmol mol-1) with three soil moisture levels in controlled environment. Slow growth rate and altered crop phenology of soybeans were observed under elevated [CO2] at early stage (V-3/V-4), but showed positive physiologically response at later stage (R3) indicating adoptive mechanism of plants to high [CO2]. Elevated [CO2] decreases the number of leaves by 23% and 14% and reduces in leaf areas by 11.7% and 9.7% compared with ambient [CO2] at 29 and 44 days after planting (DAP), respectively. Adaptive mechanism of plants to high [CO2] produced 39% and 83.7% greater leaf number and leaf areas, respectively at later stage (R3) of the crop growth (59 DAP). There was a reduction in a specific leaf area (SLA) at 29 DAP (22.2%) but an increase at 44 DAP (1.4%) and 58 DAP (8.5%) under elevated [CO2]. Dry matter production of plants was increased significantly for elevated [CO2]. Increase in leaf C (<1%) and reduction in N concentration (6.0% - 9.5%) increased the C:N ratio of soybean leaves (4.4% - 12.98%) under elevated [CO2]. Elevated [CO2] with normal soil moisture condition produced a maximum number of pods (54.8% - 122.4%) and an increase in dry weight of pods (29.8% - 56.6%). Plants under elevated [CO2] produced significantly greater numbers of root nodules per plant by 114% compared with plants under ambient [CO2] at 44 DAP. These results show a direct and interactive effect of elevated [CO2] and soil moisture on plant growth that will affect not only the global food security but also nutritional security.

Design and Performance Evaluation of Piezo-Driven Synthetic Jet Devices  [PDF]
M. Chiatto, L. de Luca
World Journal of Engineering and Technology (WJET) , 2016, DOI: 10.4236/wjet.2016.43D014
In the last two decades synthetic jet actuators have gained much interest among flow control techniques due to their short response time, high jet velocity and absence of traditional piping, that matches the requirements of reduced size and low weight. A synthetic jet is generated by the diaphragm oscillation (generally driven by a piezo- electric element) in a relatively small cavity, producing periodic cavity pressure variations associated to cavity volume changes. The high pressure air exhausts through an orifice, converting membrane elastic energy in jet kinetic energy. This review paper faces the development of various lumped-element models (LEM) as practical tools to design and manufacturing actuators. LEM can predict quickly device performances such as frequency response in terms of membrane displacement, cavity pressure and jet velocity, as well as efficiency of energy conversion of input Joule power into useful kinetic power of air jet. Actuator performance is analyzed also by varying typical geometric parameters such as cavity height and orifice diameter and length, through a proper dimensionless form of the governing equations.
PET Oligomer Waste to Modify CAP Characteristics  [PDF]
L. C. Mendes, M. L. Dias, P. S. C. Pereira, L. M. R. Albuquerque
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.38082
Abstract: To develop an improved method of reusing poly(ethylene terephthalate) (PET) waste in the production chain, it was chemically modified with pentaerythritol (PENTE), resulting in PET/PENTE (60/40) oligomer. This was added to petroleum asphalt cement (CAP) in different proportions—5, 10 and 20 wt%—as a modifier of bitumen characteristics. The mixture was evaluated by thermogravimetry (TG/DTG), differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR), optical microscopy (OM) and the adhesion-peel test. The oligomer enhanced substantially the asphalt thermal stability-Tonset. OM images showed strong compatibility between components and PET’s amorphization. PET oligomer increased CAP’s wettability and the mixture presented cohesive fracture through the peel test. The mixture has excellent potential as paving material.
Acid-Functionalized Nanoparticles for Pretreatment of Wheat Straw  [PDF]
D. Wang, M. Ikenberry, L. Pe?a, K. L. Hohn
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2012, DOI: 10.4236/jbnb.2012.33032
Abstract: Perfluoroalkylsufonic (PFS) and alkylsufonic (AS) acid-functionalized magnetic nanoparticles were synthesized and characterized, then evaluated for their ability to hydrolyze hemicelluloses. The magnetic core was made of cobalt spinel ferrite and was coated with silica to protect it from oxidation. The silanol groups allowed surface chemical modification of the nanoparticles with the PFS and AS acid functionalities. Thermogravimetric analysis gave a total organic load of 12.6% and 32.5% (w/w) for AS and PFS nanoparticles, respectively. The surface sulfur content was calculated from XPS analysis as 1.37% and 1.93% for PFS and AS nanoparticles, respectively. Wheat straw samples were treated with the acid-functionalized nanoparticles at two different conditions: 80℃ for 24 h and 160℃ for 2 h. These experiments aimed to hydrolyze wheat straw hemicelluloses to soluble oligosaccharides. PFS nanoparticles solubilized significantly higher amounts of hemicelluloses (24.0% ± 1.1%) than their alkyl-sulfonic counterparts (9.1% ± 1.7%) at 80℃, whereas the hydrothermolysis control solubilized 7.7% ± 0.8% of the original hemicelluloses in the sample. At 160℃, PFS and AS nanoparticles gave significantly higher amounts of oligosaccharides (46.3% ± 0.4% and 45 ± 1.2%, respectively) than the control (35.0% ± 1.8%). The hemicelluloses conversion at 160?C reached 66.3% ± 0.9% using PFS nanoparticles and 61.0% ± 1.2% using AS nanoparticles compared with the control experiment, which solubilized 50.9% ± 1.7% of hemicelluloses in the biomass.
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