Usual Trend Research Articles

Permeability and solubility of carbon dioxide in different glassy polymer systems with and without plasticization

The description of permeability and solubility of CO2 in different complex polymer matrices in the glassy state is analyzed by considering the diffusion coefficient as the product of a kinetic factor, mobility, and a thermodynamic factor associated to the concentration dependence of the chemical potential of the diffusing species, according to what recently presented for different pure polymers [Minelli and Sarti, J. Membr. Sci. 435 (2013) 176–185]. The thermodynamic factor is calculated in a predictive way by using the nonequilibrium lattice fluid model (NELF) or is obtained directly from experimental solubility isotherms, when pure component parameters for the NELF model are not available. The mobility factor is considered to depend exponentially from penetrant concentration, following the usual trend commonly found experimentally, and its expression contains only two adjustable parameters. The permeability model is used to describe steady state permeation of CO2 in a series of complex glassy phases, formed by polysulfone (PSf) and polyphenylene oxide (PPO) with different plasticizers, glassy polymer blends, glassy random copolymers and crosslinked polyimides. The analysis shows that in all the cases examined, the model used is able to describe the experimental trends in a simple and effective way, accounting for all the different behaviors observed, in which permeability is either decreasing or increasing with upstream pressure and even when permeability is non-monotonous and presents a minimum value due to the so-called plasticization effect. A general correlation is also found for both model parameters: the infinite dilution mobility correlates well with the reciprocal fractional free volume, according to the FFV theory, while the plasticization factor is associated to the swelling coefficient of the polymer matrix.

Permeability and diffusivity of CO2 in glassy polymers with and without plasticization

The description of permeability and diffusivity in glassy polymers has been revisited by considering the diffusion coefficient as the product of a kinetic factor, mobility, and a thermodynamic factor associated to the concentration dependence of the chemical potential of the diffusing species. The latter term does not contain any adjustable parameter since it is obtained directly from solubility isotherm data or can be even calculated in a predictive way by using well established predictive procedures as the Non Equilibrium Thermodynamics for Glassy Polymers (NET-GP) models. The mobility factor considered is endowed with an exponential dependence on penetrant concentration, following the usual trend commonly found experimentally, thus containing only two adjustable parameters. The resulting expressions for diffusivity and for permeability describe rather carefully the pressure dependence observed in glassy polymers, both in steady state permeation and in transient mass uptake, in all the cases inspected, even in the presence of the so called plasticization effects.

A Novel Homologous Series of Thermotropic Mesogens of Ethylene Derivatives: α-4-[4′-n-Alkoxy Benzoyloxy] Phenyl β-4″Methoxy Benzoyl Ethylenes

A novel homologous series consists of 12 compounds. The shorter chain homologues do not show liquid crystal phases, but from six carbons onwards, the nematic phase is exhibited enantiotropically, with some members also showing a smectic phase. The phase behavior of the transition curves of the series shows a usual trend. The texture of the nematic phase is the threaded or Schlieren type and that of smectic phase is a smectic A. An odd–even effect is observed for smectic–nematic and nematic–isotropic transition curves. Analytical data confirm the molecular structure. The transition temperatures were determined by an optical polarizing microscopy. The mesogenic properties of the novel series are compared with a structurally similar homologous series. The average smectic–nematic and nematic–isotropic thermal stabilities are 133.4°C and 159.8°C, respectively, with a mesogenic temperature range of 10°C to 62°C.

Complex Bilding Behavior of 2 ((4-Methyl-5-Nitro-6- (Pyrolidine-1-yl)Pyrimidine-2-yl)Amino)Propionic Acid in Aqueous Solution

The acidity constants of MNPPAP1 were determined by potentiometric pH titration. The stability constants of the 1:1 complexes formed between M2+: Ca2+, Mg2+, Mn2+, Co2+, Ni2+, Cu2+ or Zn2+ and MNPPAP2-, were determined by potentiometric pH titration in aqueous solution (I =0.1 M, NaNO3, 25℃). The order of the stability constants was reported. It is shown that the stability of the binary M(MNPPAP) complexes is determined by the basicity of the carboxyl or amino group. All the stability constants reported in this work show the usual trend. The obtained order is Ca2+ 2+ > Mn2+ Co2+ Ni2+ Cu2+ > Zn2+. The observed stability order for MNPPAP follows approximately the Irving-Williams sequence. It is shown that regarding to M ion-binding properties vital differences on complex bilding were considered. It is demonstrated, that in M-MNPPAP complexes, M ion is coordinated to the carboxyl group, M ion is also able to bild macrochelate over pyrimidine group. The up mentioned results demonstrate that for M-MNPPAP complex the stability constants is also largely determined by the affinity of M2+ for carboxyl group. It is shown that MNPPAP can exert a direct influence on reaction mechanism through different kinds of metal ions and donor groups of MNPPAP.

Excluded volume effect of counterions and water dipoles near a highly charged surface due to a rotationally averaged Boltzmann factor for water dipoles

Water ordering near a negatively charged electrode is one of the decisive factors determining the interactions of an electrode with the surrounding electrolyte solution or tissue. In this work, the generalized Langevin-Bikerman model (Gongadze-Iglič model) taking into account the cavity field and the excluded volume principle is used to calculate the space dependency of ions and water number densities in the vicinity of a highly charged surface. It is shown that for high enough surface charged densities the usual trend of increasing counterion number density towards the charged surface may be completely reversed, i.e. the drop in the counterions number density near the charged surface is predicted.

Evolution of organic matter during the mesophilic composting of lignocellulosic winery wastes

Winery wastes were composted in the laboratory during five months in order to study the composting process of lignocellulosic wastes. In a first experiment, spent grape marc was composted alone, and in a second one, hydrolyzed grape marc, which is the residue generated after the acid hydrolysis of spent grape marc for biotechnological purposes, was composted together with vinification lees. During the composting of spent grape marc, total organic matter did not change, and as total N increased only slightly (from 1.7% to 1.9%), the reduction in the C/N ratio was very low (from 31 to 28). The mixture of hydrolyzed grape marc and lees showed bigger changes, reaching a C/N ratio around 20 from the third month on. Water-soluble organic matter followed the usual trend during composting, showing a progressive decrease in both experiments. Although the mixture of hydrolyzed grape marc and lees presented the highest initial water-soluble carbon concentrations, the final values for both experiments were similar (8.1 g kg−1 for the spent grape marc, and 9.1 g kg−1 for the mixture). The analysis of the humification parameters did not allow an adequate description of the composting process, maybe as a consequence of the inherent problems existing with alkaline extractions. The total humic substances, which usually increase during composting as a consequence of the humification process, followed no trend, and they were even reduced with respect to the initial values. Notwithstanding, the fractionation of organic matter into cellulose, hemicellulose and lignin enabled a better monitoring of the waste decomposition. Cellulose and hemicellulose were degraded mainly during the first three months of composting, and the progressive reduction of the cellulose/lignin ratio proved that the main evolution of these wastes took place during the first three months of composting.

New tris-3,4-HOPO lanthanide complexes as potential imaging probes: complex stability and magnetic properties

There is a growing interest in the development of new medical diagnostic tools with higher sensibility and less damage for the patient body, namely on imaging reporters for the management of diseases and optimization of treatment strategies. This article examines the properties of a new class of lanthanide complexes with a tripodal tris-3-hydroxy-4-pyridinone (tris-3,4-HOPO) ligand - NTP(PrHP)(3). Among the studies herein performed, major relevance is given to the thermodynamic stability of the complexes with a series of Ln(3+) ions (Ln = La, Pr, Gd, Er, Lu) and to the magnetic relaxation properties of the Gd(3+) complex. This hexadentate ligand enables the formation of (1 : 1) Ln(3+) complexes with high thermodynamic stability following the usual trend, while the Gd-chelates show improved relaxivity (higher hydration number), as compared with the commercially available Gd-based contrast agents (CAs); transmetallation of the Gd(3+)-L complex with Zn(2+) proved to be thermodynamically and kinetically disfavored. Therefore, NTP(PrHP)(3) emerges as part of a recently proposed new generation of CAs with prospective imaging sensibility gains.

Monitoring Composites under Bending Tests with Infrared Thermography

The attention of the present paper is focused on the use of an infrared imaging device to monitor the thermal response of composite materials under cyclic bending. Three types of composites are considered including an epoxy matrix reinforced with either carbon fibres (CFRP) or glass fibres (GFRP) and a hybrid composite involving glass fibres and aluminium layers (FRML). The specimen surface, under bending, displays temperature variations pursuing the load variations with cooling down under tension and warming up under compression; such temperature variations are in agreement with the bending moment. It has been observed that the amplitude of temperature variations over the specimen surface depends on the material characteristics. In particular, the presence of a defect inside the material affects the temperature distribution with deviation from the usual bending moment trend.

Enhancing Li Ion Conductivity of Garnet-Type Li5La3Nb2O12 by Y- and Li-Codoping: Synthesis, Structure, Chemical Stability, and Transport Properties

Novel Li-stuffed garnet-like “Li5+2xLa3Nb2–xYxO12” (0.05 ≤ x ≤ 0.75) was prepared via solid-state reaction in air and characterized using ex situ and in situ powder X-ray diffraction (PXRD), 7Li and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR), scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA), and AC impedance spectroscopy. Rietveld refinement with the PXRD data confirmed the formation of a cubic, garnet-like Ia-3d structure. 7Li MAS NMR showed a single sharp peak close to 0 ppm as the usual trend for fast Li ion conducting garnets. Among the materials studied, “Li6.5La3Nb1.25Y0.75O12” showed a very high bulk ionic conductivity of 2.7 × 10–4 S cm–1 at 25 °C, which is the highest value found in garnet-type compounds, and is only reported for Li7La3Zr2O12. The in situ PXRD measurements revealed structural stability up to 400–600 °C after water treatment as well as chemical compatibility with high voltage Li cathodes Li2MMn3O8 (M = Co, Fe). The current work demonstrates...

Complex Bilding Behavior of L-Tryptophan and Related Amino Acids, a Comparative Investigation

The acidity constants of Tryptophan1 were determined by potentiometric pH titration. The stability constants of the 1:1 complexes formed between M2+: Ca2+, Mg2+, Mn2+, Co2+, Ni2+, Cu2+ or Zn2+ and Trp2−, were determined by potentiometric pH titration in aqueous solution (I = 0.1 M, NaNO3, 25°C). The order of the stability constants was reported. It is shown that the stability of the binary M(Trp) complexes is solely determined by the basicity of the carboxyl or amino group. All the stability constants reported in this work show the usual trend. The obtained order is Ca2+ Zn2+. The observed stability order for Tryptophan follows the Irving-Williams sequence. It is shown that regarding to M ion–binding properties vital differences on complex bilding were considered. It is demonstrated, that in M−Trp complexes, M ion is coordinated to the carboxyl group, M ion is also able to bild macrochelate over amino group. The up mentioned results demonstrate that for M−Trp complex the stability constants is also largely determined by the affinity of Cu2+ for amino group. It is shown that Trp can exert a direct influence on reaction mechanism through different kinds of metal ions and donor groups of Trp.

Daňové úlevy pro zaměstnance podporující sportovní družstva dětí a mládeže

The aim of this article is to increase incomes to the budgets of teams of children and young people by using income tax. Th e changes in the usual trend could also arouse greater interest in supporting neighbourhood sport. Variability and creativity are broad and a general solution does not exist. Changes to current support in the form of gift s in cash, gift s in kind and getting money from employers are proposed in such a way that they might be used to reduce tax liability. Because the fi nancial burden is shift ed to parents, the law should take their activity into account. Most of the proposals are also applicable to adult teams. By modernization of their activity the clubs could get higher prestige, higher attractiveness and larger amounts of money.

Influence of boron addition on the microstructure, structural and magnetic properties of Ni53.5Mn26.0Ga20.5 alloy

Investigations on Ni53.5Mn26.0Ga20.5Bx system with x = 0, 0.5 and 1.0 show that boron addition does not alter the monoclinic crystal structure, but modifies the superstructural ordering of the boron-free parent compound. Observed reduction in the martensitic transformation temperature by nearly 30 K differs from the usual trend expected with a rise in electron concentration. Contrary to the reports on Ni–Mn–Ga alloys with boron substitution, saturation magnetization at low temperatures increases substantially (∼19% per formula unit) on boron addition. The observed large rise in magnetization is correlated to the compositional shift in the majority matrix phase caused by the secondary phase segregation at the grain boundaries, promoted by addition of B. Formation of Ni-rich secondary phase and the associated reduction in Ni content in the matrix phase results in redistribution of Mn atoms at Mn and Ga sites. This causes an effective change in the balance between Mn moments with ferro- and anti-ferromagnetic order in the unit cell, thus explaining the magnetic properties.

Unusual room temperature CO2 uptake in a fluoro-functionalized MOF: insight from Raman spectroscopy and theoretical studies

We herein report an unusual CO(2) adsorption behavior in a fluoro-functionalized MOF {[Zn(SiF(6))(pyz)(2)]·2MeOH}(n) (1) with a 1D channel system, which is made up of pyrazine and SiF(6)(2-) moieties. Surprisingly, desolvated 1 (1') adsorbs higher amounts of CO(2) at 298 K than at 195 K, which is in contrast to the usual trend. Combined Raman spectroscopic and theoretical studies reveal that slanted pyrazine rings in 1' with an angle of 17.2° with respect to the (200) Zn(II)-Si plane at low temperature block the channel windows and thus reduce the uptake amount.

Can the Miscibility of Telechelic Polymer Solutions Increase with Polymer Chain Length?

Increasing the molar mass of the polymers in blends and in solutions tends to decrease miscibility, but application of the lattice cluster theory for strongly interactiong polymer systems to telechelic polymer solutions explains why this usual trend can be inverted, a situation actually observed in some telechelic polymer solutions and blends.

Impact of adapting Cloud Computing Technology in hospital for patient care and service

This paper deals with the impact of cloud computing in the group of non-adopted and adopted hospitals for patient care and services. In hospitals working hour means 24 x 7 and not 9 a.m. to 5 p.m. Giving access to the consumer on his demand whenever/wherever required and pay as per the usage will be the mantra. That is expected from the cloud computing approach which gives accurate and quick access to required personal data, which can replace the usual trend in hospital’s hospitality. Advancement in technology is always required to give vast information for every healthcare professional to give the best quality of the patient care and hospital management. Cloud computing is providing services to web based technology clients as and when required by storing information in servers. In cloud computing, Virtual Machines (VM) will be running different software in parallel instead of having to run only one application leading to higher efficiency and better utilisation of computing resources. This technology drives down costs and increases resources utilisation by delivering resources for the period of requirement only and hence reduces the ICT capital budget reservation. By giving additional support to the user for getting vast information through the existing support of Google Cal,Docs,Sites, Zoomerang, YouTube etc, cloud computing also adds value. It is already used successfully in the library information systems. In a group of hospitals having cloud computing infrastructure encourage and promote the advantages available to the user community. This research is also highlighting the issues related to security of patients’ data especially related to medical reports. But only security may not be a constraint. Following a case study approach the author is studying the impact of cloud computing adoption in the context of Indian healthcare sector.

5-Mercaptotetrazoles as Synthetic Equivalents of Nitrogen-Contaning Functional Groups. The Case of the Organocatalytic Enantioselective aza-Michael Reaction

5-Mercaptotetrazoles have been identified as useful and versatile Michael donors in enantioselective amine-catalyzed aza-Michael reactions with α,β-unsaturated aldehydes, showing excellent behavior as N-nucleophiles instead of their usual trend to react as S-nucleophiles. In addition several unprecedented chemical modifications on the tetrazolothione moiety have been carried out leading to the enantioselective preparation of different compounds incorporating nitrogen-containing functionalities such as oxazinimines, formamidines, ureas and isoureas.

Anomalies and other concerns related to the critical heat flux

This paper summarizes various unusual trends in the critical heat flux (CHF) that have been observed experimentally in tubes or bundle subassemblies. They include the following: • Occurrence of a minimum in the CHF vs. quality ( X) curve at high flows – leading to an initial upstream CHF occurrence in uniformly heated channels. This phenomenon has been observed at high flows in both water and Freon. • Occurrence of a limiting quality region on the CHF vs. X curve where the CHF drops by 30–90% for a nearly constant quality. This is thought to correspond to the boundary between the entrainment controlled and the deposition controlled region and causes problems for prediction methods of the form CHF = f( X). • Impact of flow obstructions on the occurrence of upstream CHF and the limiting quality region. The additional mixing by grid spacers or bundle appendages results in a more homogeneous phase distribution, and diminishes the effects of flow regime/heat transfer regime transitions responsible for some of the unusual CHF trends, and results in a more gradually decreasing CHF vs. X curve. • Absence of a CHF temperature excursion at high flows and high qualities – this is found to be caused by a change in slope of the transition boiling part of the boiling curve from a negative value (usual trend that results in a temperature excursion) to a positive slope. • Gradual disappearance of the sharp temperature excursion at CHF when increasing the pressure towards and beyond the critical pressure – no drastic change is observed in the axial temperature distribution of a heated tube experiencing CHF when, for constant mass flux and inlet temperature, the pressure is gradually increased from subcritical to supercritical. • CHF fluid-to-fluid modelling: differences in CHF trends at certain conditions between refrigerants and water at equivalent conditions. The mechanisms responsible for these trends and the implications for bundle geometries are discussed. Concerns regarding the reported uncertainty of predicted CHF values and the range of application of CHF prediction methods are also discussed.

Some important aspects of thermal elastohydrodynamic lubrication

Thermal effect in elastohydrodynamic lubrication (EHL) has been the subject of study for the last four decades; however, some important aspects related to the physical behaviour of the lubricant in response to pressure, temperature, and shear rate remain largely neglected. This paper presents a brief review of the thermal EHL literature and sheds light on the importance of accurate characterization of the lubricant properties such as viscosity, density, rheology, and thermal conductivity. Full thermal EHL line contact simulations under steady-state and transient conditions show that using the ambient value of thermal expansivity, which has been the usual trend, may overestimate the central film thickness and introduce unrealistic features in transient EHL characteristics. Also, it is demonstrated that the most extensively used rheological equation – the sinh law – for characterizing the behaviour of shear-thinning lubricants underestimates the effect of viscous heating on EHL traction and film thickness.

Deposition of SBA-15 layers on Fecralloy monoliths by washcoating

Abstract Stable slurries or suspensions were prepared in order to carry out deposition of SBA-15 layers onto Fecralloy monoliths by washcoating. The suspensions presented an important evolution with ageing time under magnetic stirring, that consisted of a change in viscosity. This change was directly related to the abrasive effect of the magnetic stirring, and caused the breakdown of the big aggregates of the parent SBA-15 into rod-shaped units that became more and more irregular, and the slurries to become less viscous compared with the established usual trend. The viscosity was suitable for washcoating after 120 h of magnetic stirring. Although a clear macroscopic effect was observed, the mesoporous nature of the solid was preserved. The amount loaded and the adherence of the coatings depended on the formulation of the slurry. The best results were obtained when colloidal silica was used as a binder.

Dielectric and Spectroscopic Studies of A Fly Ash Blended Cement Paste

The dielectric constant (?') of Sulfate Resisting Portland Cement (SRPC) blended with 30% of fly ash by addition ismeasured using microwave bench at 9.54 GHz, for initial 30 hours of hydration. The heat of hydration for the sameblend using heat of solution calorimetry is also measured. It is observed that contrary to the usual trend of retarding offly ashes, it shows an accelerating trend with increasing strength as times passes. SEM micrographs and XRD patternsare also recorded and observed that C4Al2SO16 (C4A3S¯) is found to be responsible for the accelerating trend of the mix.The hydration process in the early period is studied and it is suggested that suitable retarder should be adopted for theeffective utilization.Cement chemistry notations: C=CaO, A=Al2O3, S¯=SO3, H=H2O, F=Fe2O3, S=SiO2