Effect of clay amount and reprocessing cycles on thermal,morphological, and mechanical properties of polypropylene/organovermiculite nanocomposites

Nanocomposites of polypropylene (PP) and PP‐grafted‐maleic anhydride (PP‐g‐MA) with and without organophilic vermiculite (OVMT) (5–8%w/w) were evaluated. The nanocomposites and neat PP were submitted to extrusion reprocessing cycles. It was found that the presence of OVMT in PP/PP‐g‐MA was critical for maintaining thermal stability during reprocessing. The exfoliation/intercalation was confirmed, mainly, in the nanocomposite submitted to reprocessing cycles, by X‐ray diffraction. The melt flow index (MFI) values for the 3× and 5× reprocessed PP increased by 40% and 70%, respectively, as compared to the neat PP. The MFI for the 3× and 5× reprocessed PP/PP‐g‐MA/OVMT decreased 26% and 17%, respectively, as compared to the decrease occurred in the 3× and 5× reprocessed PP, indicating that the presence of 5% (w/w) OVMT was sufficient to allow an increase in viscosity. The reprocessed nanocomposites exhibited values for tensile and flexural strengths and Izod impact, in general, greater than or near to those of PP with the same number of reprocessing cycles. The increase or maintenance of mechanical properties seems to depend on a balance between the extent of intercalation/exfoliation and dispersion of OVMT in the PP matrix, and the degree of degradation of the PP matrix. POLYM. ENG. SCI., 59:2110–2120, 2019. © 2019 Society of Plastics Engineers     

Modeling Lebanon’s electricity sector: Alternative scenarios and their implications

This paper is concerned with modeling possible future paths for Lebanon’s electricity future and evaluating them. The baseline scenario (BS) reflects the business-as-usual state of affairs and thus describes the most likely evolution of the power sector in the absence of any climate change-related or other policies. Two alternative scenarios are examined in contrast to the BS; the renewable energy scenario (RES) and the natural gas scenario (NGS). Using the Long range Energy Alternatives Planning System (LEAP) software we conduct a full-fledged scenario analysis and examine the technical, economic, and environmental implications of all scenarios.From an economic standpoint as well as from an environmental perspective both alternative scenarios are superior to the baseline. Hence, the results of the simulation show that the alternative scenarios are more environmentally and economically attractive than the BS. They would help Lebanon meet its social, environmental, and economic development goals, while at the same time providing other unquantifiable benefits that are discussed further in the paper. Anticipated barriers to the shift in energy mix from conventional sources to renewable energy sources are also presented and discussed     

Evaluation of absorption kinetics of oxygen scavenger sachets using response surface methodology

The performance of oxygen scavengers can be influenced by several conditions, such as temperature (T) and relative humidity (RH), which are considered to be the two major factors. Therefore, the development of new scavengers requires the study of their performance, with these conditions varied. In this paper, the response surface methodology (RSM) was used to study the performance of a newly developed oxygen scavenger sachet and to model the influences of T and RH and their interaction on the absorption capacity and rate constant of the developed sachet. Commercial oxygen scavenger sachets were used for comparison purposes. The oxygen absorption capacity and rate constant were evaluated with a 2² factorial design with a central point. The results showed that each absorber sachet presented a different behaviour and there were significant interactions between T and RH; so, the RSM was the most appropriate for these studies. The developed sachet presented a better performance compared with the commercial ones at 23°C and 53% RH, which represents the condition for commercialization at room temperature of foods of intermediary water activity, while in the extreme conditions (100% RH and 37°C) all sachets present a similar absorption capacity. Copyright © 2010 John Wiley & Sons, Ltd.     

Template-based finite-element mesh generation from medical images

The finite-element (FE) method is commonly used in biomedical engineering to simulate the behaviour of biological structures because of its ability to model complex shapes in a subject-specific manner. However, generating FE meshes from medical images remains a bottleneck. We present a template-based technique for semi-automatically generating FE meshes which is applicable to prospective studies of individual patients in which FE meshes must be generated from scans of the same structure taken at different points in time to study the effects of disease progression/regression. In this "template-based" meshing approach, the baseline FE (tetrahedral) volume mesh is first manually aligned with the follow-up images. The triangulated surface of the mesh is then automatically deformed to fit the imaged organ boundary. The deformed surface nodes are then smoothed using a Laplacian smoothing algorithm to correct triangle (surface nodes) distortion and thus preserve triangle quality. Finally, the internal mesh nodes are smoothed to correct distorted tetrahedral elements and thus preserve tetrahedral element quality. This template-based approach is shown to be as accurate and precise as the previous technique used by our group, while preserving element quality and volume.     

Isomerisation of α-Pinene Oxide on Sulfated Oxides

The acid properties of sulfated alumina, titania and zirconia have been characterised, and these solids compared in the isomerisation of -pinene oxide in the liquid phase at 273 K. This comparison shows that the formation of campholenic aldehyde requires a mild Lewis acid. Only sulfated alumina is a good catalyst giving yields reaching 76% at full conversion in less than 1 h, though with a relatively high catalyst:reactant ratio. The conditions of preparation of this solid show a significant influence on the acid properties and therefore on the catalytic properties of the resulting solid. The best results are obtained with sulfated alumina prepared with a ratio of hydrolysis of 1 and an activation temperature of about 923 K.     

The relationship between the psychological investigator and the public schools.

In an effort to create a reciprocating arrangement between university and various school systems, "a facility, designated the Office of Child Research was recently established at the University of Texas." This unit provides assistance to the investigator in the preparation of the research proposal, submits the research proposal, informs the investigator of the disposition of his proposal and assists in preliminary arrangements, reports to the school on completion of the study, provides a variety of reciprocating services, and maintains records. From Psyc Abstracts 36:02:2KA01C. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improvement of the Interactions between Modified ZrO2 and Poly(amide-imide) Matrix by Using Unique Biosafe Diacid as a Monomer and Coupling Agent

This research explores the synthesis of a high-performance poly(amide-imide) (PAI) from the polycondensation reaction of N-trimellitylimido-L-leucine as a bioactive diacid with 4,4′-diaminediphenylsulphone using combination of triphenyl phosphite and tetra-n-butylammonium bromide as a condensing agent. ZrO₂ nanoparticle (NP) was used as a filler for the formation of PAI nanocomposites (NC)s. For a unique dispersion of NPs in the PAI matrix, the surface of ZrO₂-NPs was modified with bioactive N-trimellitylimido-L-leucine using ultrasonic technique. The obtained polymer and modified ZrO₂-NPs were used to produce PAI/ZrO₂ NCs under ultrasonic irradiation. The obtained NCs were characterized by different methods.     

Synthesis and characterization of manganese ferrite nanostructure by co-precipitation,sol-gel,and hydrothermal methods

ABSTRACT

In this research work, manganese ferrite nanoparticles (MnFe₂O₄) were synthesized by three different methods including the co-precipitation, sol-gel, and hydrothermal route. Structure, size, morphology, and magnetic properties of nanostructures were determined and compared using X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy analysis (FESEM), and the vibration sample magnetometer (VSM). X-ray diffraction analysis from Debye–Scherrer’s formula with the (2θ?=?35.08°) peak indicated that the mean size of the synthesized manganese ferrite nanocrystallites were obtained to be 36, 45, and 16?nm for co-precipitation, sol-gel, and hydrothermal, respectively. Also, the sample prepared by the hydrothermal method has the lowest crystal sizes, which it is approved by FESEM analysis. Field emission scanning electron microscopy analysis images confirmed the existence of three types of basic morphology of MnFe₂O₄ nanoparticles: spherical shape, multi-walled hollow nanosheets, and reticular structure. In addition, Based on VSM data magnetization saturation (M_s) was 41.89?emu/g for hydrothermal synthesized samples, 38.76?emu/g for co-precipitation samples, and 9.52?emu/g for sol-gel samples. These findings show that various methods of nanoparticle synthesis can lead to different particle sizes and magnetic properties.     

Tightly trapped highly excited Rydberg atom in dipole–quadrupole potential landscape

ABSTRACT

In this paper, coherent Rydberg excitation of a single four-level atom in tightly confining trap so-called ‘far-off-resonance optical dipole-quadrupole trap’ (FORDQT) by considering Laguerre Gaussian (LG) beams spatial features is demonstrated. The self-trapping potential results from the position dependent differential AC Stark shift of the ground state and Rydberg state in the effective quadrupole Rydberg excitation. By introducing the effective stiffness of the FORDQT potential in terms of the key parameters of the first and Rydberg excitation laser beams, a technique to obtain sub-micron localization of Rydberg excitation is explored. The complete matched trapping potential of the ground state and Rydberg state near the center of the trap maintains the coherence of the Rydberg excitation. Transfer of optical orbital angular momentum from the LG-beam to the Rydberg-state via localized effective quadrupole excitation process paves the way for implementation of high fidelity qudit gates in high dimensional quantum information process.