VOLUME 44, NO4, AUG-2022

To Explore the Effect of Injection Molding Processing Parameters on Crazing in Acrylic Polymers

Plastic manufacturing industry is the fastest growing industry as the demand for plastic products is exponentially growing worldwide. Poly (methyl methacrylate) (PMMA), also known as acrylic glass, is a transparent and rigid thermoplastic. PMMA is highly resistant to UV light. Weathering has an excellent light transmission and unlimited coloring options compared to other transparent plastic and has been used in wide applications such as architecture, automotive and transportation, lighting (LED lights), medical and healthcare, and furniture. Injection molding is the widely used plastic manufacturing process to produce plastic products for various applications. The quality of the plastic products depends on the injection molding parameters, viz. melting temperature, injection speed, and pressure, holding and cooling time, and holding pressure. Therefore, it is important to control injection molding parameters to reduce injection molding defects or parts. Hence, the main objective of this research is to optimize the injection molding parameters, including the amount of mold releasing agent, to avoid the crazing marks in PMMA which is a long-standing problem in the production of PMMA products or parts such as motorbike headlight lenses. Three different holding pressures (65, 75, and 85 kg/cm2) were varied against three different injection pressures (70, 80, and 90 kg/cm2). The injection speed (60 %), cooling time (4 s), and barrel zones temperature (185-205: 185-205: 190-210: 195-215) were kept constant not to disturb the production cycle, a constraint from the production industry. The minimum criteria required for the motorbike headlight lens selection was based on the LUX intensity test, density, and crazing demanded by the Japanese standard throughout this research. The optimized injection molding parameters and amount of mold releasing agent (Nabakem mold release R2) were 70 kg/cm2 (injection pressure), 65 kg/cm2 (holding pressure), and 1.18 g, respectively. The motorbike headlight lens produced with optimized injection molding parameters showed no crazing. In addition to the desired LUX intensity, density, and no crazing criteria, the motorbike headlight lens also showed improved impact properties and no substantial changes in mechanical properties when compared to virgin PMMA or literature. Hence, it is concluded that the optimized injection molding parameters (thermo-mechanical history) did not much affect the molecular weight and morphology of the PMMA.read more

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Rafiq Ahmed, Asim Mushtaq, Saud Hashmi, Sindhia Abbasi and Zaeem Uddin Ali

Electrochemical and Computational Study of Copper Histidine Complex via Cyclic Voltammetry

L-Histidine regulates body function and involve in the synthesis of hemoglobin, repairing of tissues and strengthens of immune system. In this study, Cyclic Voltammetry (CV) is used with 0.1 M Potassium Chloride as a supporting electrolyte to determine the accurate metal ligand ratio between Cu+2 and L-Histidine. In CV potential window is set between +0.6 to -0.4V to record theVoltammogram. Voltammograms were recorded by varying scan rate from 50mV/s to 300mV/s. Cyclic Voltammetry is used to analyzed the interfacial performance of the complex and repeated CyclicVoltammograms (07 cycles) were recorded at Glassy Carbon Electrode (GCE), that shows no change in peak current intensity of both anodic and cathodic peak. Further, neither pre nor any post peak was observed. These interpretation express that reactant and product are not involve in the adsorption-desorption process at the surface of Glassy Carbon Electrode (GCE). These remarks suggest that it is diffusion controlled process in the above mentioned system. The interaction of Cu+2 and L-Histidine were not reported before through Cyclic Voltammetry. Furthermore, in this study structure of Cu+2 vs. L-Histidine complex is investigated from a theoretical perspective. Optimization of Cu+2 vs. L-Histidine complex was carried out by DFT method and result verifies that stable structure of Cu+2 vs. L-Histidine complex exist as square planar structure in 1:2 ratio respectively. The computed structure has correlation with experimental results and Voltammogram of 1:2 ratio complex of Cu+2 vs. L-Histidine suggested that it exist in Square planar geometry.read more

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Atya Hassan, Sana Gul, Taswar Ali Chandio and Muhammad Ali Minhas

Supported Ruthenium Catalysts for Oxidation of Benzyl Alcohol under Solvent Free Conditions

The investigation comprised an evaluation of the use of the catalyst, 1%Ru/TiO2, to oxidize Phenylmethanol into benzenecarbaldehyde. nitrogen adsorption isotherms and transmittance electron microscope (TEM) were deployed to delineate the properties of the supported catalysts. The findings indicated a superior catalytic performance from 1%Ru/TiO2 prepared using sol-immobilization method. No reaction was taken place with blank reaction or with undoped support. This was deemed to be a consequence of the dispersion and loading of Ru on the TiO2.The reaction conditions, i.e., temperature, reaction time, nature of catalyst and activating quantity, were optimized to achieve superior reaction parameters. This process gave rise to a benzyl alcohol transformation rate of up to 10%; and selectivity of benzaldehyde was 98%.read more

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Raiedhah Alsaiari, Moustafa A. Rizk, Esraa Musa, Huda Alqahtani, Fatima Alqadri, Mervat Mohamed, Mabkhoot Alsaiari, Ali Alkorbi, Iman Shedaiwa, Faeza Alkorbi

Hydrophilic Interaction Chromatography with Sulfobetaine Zwitterionic Polymer-Bonded Stationary Phases

A rapid method for simultaneous determination of two statin drugs based on zwitterionic chromatography (ZIC) had been developed and validated. The development method included examining the effects of chromatographic conditions, including the percentage of organic modifier, pH values, ionic strength of the acetate buffer, and the predominant retention mechanism's experimental determination. Separation developed by two zwitterionic stationary phases (100 mm × 4.6 mm I.D., 3.5µ). The influence of various spacer lengths was being used as an examination tool on atorvastatin and rosuvastatin retention behaviours. Two zwitterionic stationary phases and a mobile phase consisting of acetonitrile and acetate (pH = 4.75, 40 mM) in a ratio of 80:20 V/V were used to achieve optimum chromatographic conditions. The methods had been validated for linearity, accuracy, and precision. This validation shows that the ZIC-HILIC methods proposed were sufficient for quantification analysis of atorvastatin and rosuvastatin. Quantifications were achieved with U.V. detection at 240 nm over the concentration range of 0.1–7.0 μg mL-1 for atorvastatin and rosuvastatin, respectively.read more

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Ali Mohammed Mahir Fahad, Ashraf Saad Rasheed and Hameed Hussien Ali

Preparation, Characterization and Extraction Performance of Rubidium Ions in Water System

In this paper, a valinomycin-functionalized nano-sized magnetic solid-phase extractant (VFE) with the core-shell structure and the Fe3O4 nanospheres as the core is prepared. Related performances are characterized and tested by SEM, PPMS, XRD, FT-IR, TGA, EDS, ICP-MS, and AAS. The optimal extraction conditions are obtained, namely, temperature 50 °C or higher, pH not less than 9.3, and equilibrium extraction time about 35 min. Recycling performance experiments show that the extraction ratio of rubidium ions after 5 extraction-elution cycles is still up to 85.3%. Extraction experiments with the simulated brine, industrial wastewater, and domestic wastewater show that the VFE exhibits good selective extraction ability for rubidium ions in these water systems. This research is expected to provide a new method or a new material for the separation, extraction, enrichment, and detection of rubidium ions in water systems.read more

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Guo-jun Zhang, Hua Fu, Hui-yuan Chen, Huo Liu, Wei-jun Song, Chun-yan Sun, Xin Hu and Yun Zhao

Determination of Puerarin, Daidzein, Baicalin and Wogonin in Composite Preparations by Capillary Electrophoresis

A simple method for the simultaneous determination of four bioactive components (puerarin, daidzein, baicalin, and wogonin) in composite preparations by microemulsion capillary electrophoresis with UV detection has been developed for the first time. A running buffer composed of 8% acetonitrile + 4% microemulsion(3.24% n-heptane + 13.24% sodium dodecyl sulfate (SDS) + 26.44% n-butanol + 57.08% distilled water in weight ratio) + 20 mM borax solution was found to be the most suitable for this separation. The limits of detection for four analytes were over the range of 0.50 - 1.2 μg ml-1. In the tested concentration range, linear relationships (correlation coefficients: 0.997 for baicalin, 0.997 for wogonin, 0.998 for daidzein and 0.999 for puerarin) between the peak areas and the concentrations of the analytes were obtained. This method has been successfully applied to simultaneous determination of the four bioactive components with recoveries from 94.6 to 106.3%.read more

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Cunhong Li and Yan Xu

Metabolomic Profiling of Different Maca Color Types Using Nuclear Magnetic Resonance Spectroscopy and Multivariate Data Analysis

This study aimed to explore significant differences in chemical composition among maca (Lepidium meyenii Walp.) types with different colors in Yunnan province, China. 1H-NMR spectroscopy, in combination with principal component analysis and partial least squares discriminant analysis, was used to investigate the compounds responsible for compositional differences. Different maca color types in Yunnan were clearly distinguished by 11 differential metabolites. Furthermore, network pharmacology results showed that 30 active components were related to Alzheimer’s disease. Nine intersecting compounds among the 11 differential metabolites and 30 active components, namely, lysine, isoleucine, phenylalanine, β-hydroxybutyrate, tryptophan, pyroglutamate, proline, glutamine, and fructose, were used as bioactive markers to identify different maca color types. The results showed the bioactive markers among different maca color types holistically, providing a scientific basis for assessing the quality of commercial products derived from different maca color types.read more

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Jingwei Lv, Chunnan Li, Nanxi Zhang, Kaiyue Z., Xiaochen Gao, Na Li, Lingwen M., Yinping Y., Hui Zhang and Jiaming Sun

Determination of Pka Values of Antidiabetic Drugs from Mobility Data and Pharmaceutical Analysis by Capillary Electrophoresis

In this study, the dissociation constants of six antidiabetic drugs (rosiglitazon maleate, pioglitazone, glimepride, glibenclamide, gliclazide and glipizide) have been calculated by capillary electrophoresis (CE) technique in water from the mobilities of compounds at several pH values. The dissociation constant values of antidiabetics had been checked with the ones formerly decided withinside the literature and additionally with the statistics expected through the SPARC on-line calculator and ACDLAB. Also, easy, precise, green, accurate and completely validated CE technique for the analysis of glibenclamide in pharmaceutical medicine has been fully developed. The CE technique allowed quantitation over the ranges of 1.00-12.00 μg mL-1. The detection and quantitation limits were determined as 0.036 μg mL-1 and 0.083 μg mL-1 respectively. Rosiglitazone was used as an internal standard and short analysis time (< 3 min.) was observed. The developed capillary electrophoretic technique could be used for ordinary analysis of the glibenclamide and this method can also be used for pharmacokinetic studies.read more

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Senem Şanlı, Seyfi Sardogan, Ayşe Özdemir and Barış Atalay

In-silico, Antioxidant and Antiepileptic Effect of N(2,3-methylenedioxy-4benzoyloxy-phenthylamine)-3,4-dimethyl-1, propanoamide Derivatives

Epilepsy is a severe neurological illness that affects millions of people the globally and is characterized by unpredicted and intermittent seizures.This research aimed to investigate the antiepileptic and antioxidant properties of papaverine derivatives using in-silico, in-vitro, and in-vivo methods.Epileptic seizure was induced in Swiss albino mice of either gender by administering PTZ (pentylenetetrazol). The antioxidant potential of test compounds was computed using previously published DPPH assay methods with minor modifications, while In-silico experiments were conducted using Auto-dock Vina (1.5.6) software and post dock analysis was completed using Discovery Studio Visualizer. The results showed that both compounds have strong antioxidant potential, with a noticeable change in color when compared to ascorbic acid as a control, and very low mortality when anti-epileptic potential was observed. The development of seizures was greatly delayed at first, but after 30 minutes of PTZ, they were completely gone. Both synthesized derivatives also comply the "Lipinski's rule of 5", which states that after structural alterations, extensive investigations, and trials, the chemical products would be evaluated for epilepsy management in the future In-silico investigations demonstrated that ligands with sufficient hydrogen bonds, pi-pi bonds, and Vander-Waals forces have a suitable propensity to engage with the binding pocket of selected protein targets. The current investigation of papaverine derivatives and their binding affinities against gamma aminobutyric acid (GABA) protein may have a vital function in epilepsy aetiology, according to the results of the studies. H1 and H2 were further verified in vivo for their anticonvulsant and antioxidant therapeutic potential. This could lead to more research into neurological problems.read more

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G.A. Miana, M. Kanwal, S. Maqsood, Z. Tariq, F. Ali Shah, H. Saddam, M. Umar Farooq and Arif U. Khan

Investigation of Acrylamide Based Hydrogels as L-Dopa and L-Tyrosine Drug Release System

Acrylamide-based hydrogels exhibit significant volume migration in response to physical and chemical stimuli. These properties make their use as drug delivery systems widespread. In the study, acrylamide-based hydrogel structures were synthesized to be used as two prodrugs known as L-Dopa and L-Tyrosine carrier and release system. Fourier-transform infrared (FTIR) spectroscopy, scanning electron micrography (SEM), Image J program were used to evaluate the structure-property relationship of the synthesized hydrogels and swelling studies were performed. The maximum swelling capacity of the synthesized hydrogel structures was determined as 973.80±12.25 %. The L-Dopa loading on the hydrogel was 69.51±9.64% and the L-Tyrosine loading was 61.37±5.08%. The release behavior of the drugs loaded on the hydrogel was monitored using a UV-vis spectrophotometer at pH 7.4 and λmax 280 nm. Accordingly, it was observed experimentally that 84.21±1.71% of L-Dopa and 75.98±2.69% of L-Tyrosine were released. The study is an alternative release system with the simultaneous release of L-Dopa molecule, which is especially used in the treatment of Parkinson's disease, and L-Tyrosine, which plays an important role in the synthesis of L-Dopa.read more

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