Synthesis and characterization of conjugated and nanostructured poly(propargyl alcohol) polymers

New types of π-conjugated and colored poly(propargyl alcohol) polymers (poly-PGA) were prepared by the polymerization of propargyl alcohol (PGA) monomer in different media under the action of high energy photons, γ-rays, without the use of catalysts. The polymerization conditions depend on the used solvents (water, chloroform and dimethylformamide) and gases (O₂ and N₂). A singlet and broad electron paramagnetic resonance signal was observed in poly-PGA polymers, indicating the presence of free electrons and the delocalization of electrons through the polymer π-backbone. The synthesized polymers have FTIR bands (C=C) in the range of 1607–1652 cm^?1 and an absorption broadband in the spectrum range of 305–316 nm. The poly-PGA polymers which synthesized in chloroform and DMF exhibited amorphous structures as approved by XRD results. In addition, both TEM and DLS measurements showed the formation of nanostructured polymers in the shape of nano-spheres, nano-stars and nano-networks depending on polymerization conditions. Radiation polymerization of the monomer in chloroform produced a polychlorinated polymer as demonstrated by EDX analysis. The polymers have optical band gaps in the range of 2.85–3.50 eV and conductivity in the range of 2.45?×?10^?6 to 9.43?×?10^?7 depending on the polymerization conditions and the media used.     

Bleaching of Rice Straw Paper Pulp and Possibilities for Replacement of Sodium Hydroxide by Ammonium Hydroxide During the Extraction Stage

Bleaching of rice straw soda pulp was investigated under various conditions. The rate of the chlorination and hypochlorite reactions were studied; the best properties were attained by shortening the chlorination time to about 20 min. The extraction efficiency of ammonium hydroxide on chlorinated soda pulp was also investigated. The effectiveness of extraction can be deduced from the reduction of the kappa number, cuprammonium viscosity and the brightness obtained after the hypochlorite step. Extraction can be carried out with ammonium hydroxide instead of sodium hydroxide used in the conventional method. The strengths of unbleached and fully bleached pulps were evaluated. The fully bleached ammonium hydroxide extracted pulps were beaten faster and were usually stronger than the corresponding pulps extracted with sodium hydroxide.     

Scheduling Multi-Mode Resource-Constrained Projects Using Heuristic Rules Under Uncertainty Environment

Project scheduling is a key objective of many models and is the proposed method for project planning and management. Project scheduling problems depend on precedence relationships and resource constraints, in addition to some other limitations for achieving a subset of goals. Project scheduling problems are dependent on many limitations, including limitations of precedence relationships, resource constraints, and some other limitations for achieving a subset of goals. Deterministic project scheduling models consider all information about the scheduling problem such as activity durations and precedence relationships information resources available and required, which are known and stable during the implementation process. The concept of deterministic project scheduling conflicts with real situations, in which in many cases, some data on the activity' s durations of the project and the degree of availability of resources change or may have different modes and strategies during the process of project implementation for dealing with multi-mode conditions surrounded by projects and their activity durations. Scheduling the multi-mode resource-constrained project problem is an optimization problem whose minimum project duration subject to the availability of resources is of particular interest to us. We use the multi-mode resource allocation and scheduling model that takes into account the dynamicity features of all parameters, that is, the scheduling process must be flexible to dynamic environment features. In this paper, we propose five priority heuristic rules for scheduling multi-mode resource-constrained projects under dynamicity features for more realistic situations, in which we apply the proposed heuristic rules (PHR) for scheduling multi-mode resource-constrained projects. Five projects are considered test problems for the PHR. The obtained results rendered by these priority rules for the test problems are compared by the results obtained from 10 well-known heuristics rules rendered for the same test problems. The results in many cases of the proposed priority rules are very promising, where they achieve better scheduling dates in many test case problems and the same results for the others. The proposed model is based on the dynamic features for project topography.     

Application of alginate and gelatin-based edible coating materials as alternatives to traditional coating for improving the quality of pastirma

This research was conducted to study the efficacy of sodium alginate and gelatin coating materials in improving the quality of pastirma. Pastirma was coated with traditional, alginate or gelatin coatings, stored at 4 °C for 4 weeks and examined weekly. Alginate and gelatin coated-pastirma revealed lower TBARS values which was within the acceptable limit (0.67 and 0.86 mg/kg) until the end of storage, however, the TBARS values of traditionally coated pastirma reached 1.33 by the end of storage. Edible coating delayed respiration rate with improvement of the color when compared with traditionally coated one. Oxygen concentration increased from 4.21 mg/kg/h in traditionally coated pastirma to 12.56 and 9.79 in alginate and gelatin coated ones, respectively. Meanwhile, CO₂ concentration decreased from 10.40 mg/kg/h in traditionally coated pastirma to 4.89 and 6.07 mg/kg/h in alginate and gelatin coated ones, respectively. Moreover, a distinct improvement in all sensory attributes has been observed.     

8 Gbits/s inductorless transimpedance amplifier in 90 nm CMOS technology

This work presents the design and the measured performance of a 8 Gb/s transimpedance amplifier (TIA) fabricated in a 90 nm CMOS technology. The introduced TIA uses an inverter input stage followed by two common-source stages with a 1.5 kΩ feedback resistor. The TIA is followed by a single-ended to differential converter stage, a differential amplifier and a 50 Ω differential output driver to provide an interface to the measurement setup. The optical receiver shows a measured optical sensitivity of ?18.3 dBm for a bit error rate = 10^?9. A gain control circuitry is integrated with the TIA to increase its input photo-current dynamic range (DR) to 32 dB. The TIA has an input photo-current range from 12 to 500 μA without overloading. The stability is guaranteed over the whole DR. The optical receiver achieves a transimpedance gain of 72 dBΩ and 6 GHz bandwidth with 0.3 pF total input capacitance for the photodiode and input PAD. The TIA occupies 0.0036 mm² whereas the complete optical receiver occupies a chip area of 0.46 mm². The power consumption of the TIA is only 12 mW from a 1.2 V single supply voltage. The complete chip dissipates 60 mW where a 1.6 V supply is used for the output stages.     

Spectroscopic analysis and mechanical properties of electron beam irradiated polypropylene/epoxidized natural rubber (PP/ENR) polymer blends

Polymer blends based on different ratios of polypropylene (PP) and epoxidized natural rubber (ENR) were prepared by melt extrusion into sheets. The PP/ENR blends were exposed to various dose of accelerated electrons. The formation of free radicals during and after electron beam irradiation was illustrated by electron spin resonance (ESR). Also, the effect of electron beam irradiation on the mechanical and structural morphology was investigated by stress-strain behavior and scanning electron microscope (SEM). The ESR spectra indicated the formation of alkyl and allyl radicals during electron beam irradiation and peroxyl radicals during the post effect. The rate of radical decay was found to be second-order kinetics. The improvement in mechanical properties and structural morphology was confirmed to be due to the effect of electron beam irradiation.     

Design and Characterization of a New Food Packaging Material by Recycling Blends Virgin and Recovered polyethylene terephthalate

This research is dealing with plastic wastes recycling environmental problem. The objective is the polyethylene terephthalate (PET) valorization from postconsumer bottles by the optimization of the most suitable virgin and recycled PET mixture to be used as food contact packaging. Mixtures of these materials were elaborated by extrusion and injection molding using different recycled PET rates. Rheological, mechanical, and thermal analyses were achieved, and then migration tests were investigated to assess the recycled PET compatibility for food contact packaging. The rheological analysis showed a PET degradation after the mechanical recycling, with PET viscosity decrease, compared to that of the virgin material. The blends properties showed that at low deformation, mechanical properties were significantly improved by adding recycled PET. Consequently, the new material was more rigid with a crystallinity degree improvement, increasing the materials resistance that enhanced their tenacity. However, at great deformations, the PET mixed materials were deteriorated through drastic ductility losses. The mixture 30/70 recycled/virgin PET seems to be the best blend. For all the studied mixtures, the overall migrations conformed the European Standard, allowing the use of the recycled PET for packaging as an issue in circular economy principles for a sustainable development. POLYM. ENG. SCI., 60: 250–256, 2019. © 2019 Society of Plastics Engineers     

Impact of sulphur-containing compounds on the electrochemical capabilities of spinel carbon-coated Sb2SnS4 nano-sheets as alternative anodes in lithium ion batteries

Journal of Materials Science: Materials in Electronics - In this paper, three different samples of spinel carbon@Sb2SnS4 (C@S) sulphide were successfully synthesized via simple hydrothermal...     

Packaging design elements and consumers' decision to buy from the Web: A cause and effect decision‐making model

Recent advances in e‐commerce have resulted in significant progress being made toward strategies, requirements, and the development of various mechanisms aimed at influencing consumers' decisions to purchase online. The relationship between different packaging design elements and their effect on consumers' online buying decisions has been less researched, due in part to the lack of statistical power to detect cause and effect relationships between these elements. This study examines the feasibility of multiple‐criteria decision‐making in order to identify and analyze the causal relationships between the different packaging design elements that are required to stimulate consumers' decision to buy products online. Consumers' direct, indirect, and interdependent behaviors in relation to PDEs and purchase decisions were studied for this paper. A total of 142 students (89 males and 53 females, aged 22‐37 years) participated in this study. The results identified several associations between design elements. The four most important PDEs found to influence consumers' decision to buy via the internet were graphics, colours, label information, and country of origin. This study provides the necessary insights into the design of product packaging by targeting aspects related to the appearance of the products' characteristics. Correlations between the various PDEs obtained from this study can be used to increase consumers' interactions with products in e‐commerce environments.