Advanced Journal of Chemistry, Section A
Volume:4 Issue: 2, Spring 2021

In this study, an efficient method was performed to extract and measure the Cu(II) metal ions using the modified disks of octadecyl silica membrane by nano-Fe3O4-encapsulated-dioctyl phthalate and linked-diethylenetriamine (magnetic nano- Fe3O4 -DOP- DTA). This method involves forming a complex on the ENVI-18 DISKTM surfaces, followed by maintained species removed from the surface with the least amount of organic solvent. The act of elution in this technique is very impressive. The important factors are including the pH, stripping solvent, ligand values, rate of sample flow, and the effect of interfering ions were evaluated. The preconcentration factor was 500 in the optimum analysis situations of whole parameters. Analysis parameters contain the limit of detection and the most capacity of copper (II) ions sorption was achieved 6 μg/L and 385 ± 5 µg, respectively. Finally, the Cu2+ ions were extracted in various aqueous solutions by this technique.

Ortho-vanillin Schiff baseare multipurpose ligands which are synthesized from the condensation of 2-Hydroxy-3-methoxybenzaldehyde with amines compounds to designing an infinite number of potential compounds. Ortho-vanillin Schiff base grow into very common in coordination chemistry for the reason that it can form compounds that have high stability with most metals, and this is due tonitrogen (N) of azomethine group beside two oxygen (O) atoms of hydroxyl and methoxy groups. Ortho-vanillin Schiff base and its metal complexes are very important as antibacterial, antifungal, antioxidant and anticancer, Also, many available pharmaceutical researches predict how these compounds can interaction with DNA. Many efforts are made in the possibility of using Ortho-vanillin Schiff baseas catalyst, polymers, dyes, Analogues and pharmaceutical fields.  This review will try to shed light on the most used applications by researchers of Ortho-vanillin Schiff base compounds to stimulate more and more efforts to achieve maximum benefit from potential infinite number of compounds.

In this paper, molecular diameter for various pure compounds are estimated by seven methods, in which three diameters are based on scaled particle theory (SPT) and the others are obtained from actual molecular volumes assuming hard sphere shape for molecules by using Bondi, Edward and Van der Veen methods. The seventh one is obtained from a relationship between molecular volume and parachor. Correlation among seven types of molecular sizes for pure components is reported. Calculated diameters are used to prediction surface tension of 108 pure compounds based on SPT. Calculation results show that the hard sphere diameter which is obtained from reported correlations can be used for estimation of pure substances surface tension with good accuracy.

The pandemic has brought both challenges and opportunities to all universities across the globe. Every challenge will open the door for new opportunities. As the world was fighting against the global pandemic, all universities were transitioned online over a short period without any prior preparation. Over time as an instructor, I shape myself for combating the situation. Utilizing Zoom, whiteboard, molecular model, videos, ChemDraw, Respondus, LockDown Browser, blackboard, mandated attendance, interactive class, and office hour, this instructor was able to facilitate the learning process compatible with the face-to-face model. Laboratory was the blend of lab manuals, lab videos, and simulation experiments. Prelab, quiz, and report were prepared based on the lab manual and lab video. Similarly, simulation experiments were conducted for each lab via Beyond Labz which helped to connect the lecture with the techniques of the laboratory.  In fall 2020, a survey was conducted on sixty students representing different organic chemistry lectures (CHEM 2311) and laboratories (CHEM 2111) at the University of the Incarnate Word, San Antonio, Texas. The outcome of the survey revealed that live synchronous with mandated attendance and office hour fulfills the expectations of the students as well as the standards of the course. This instructor’s perspective also aligned with the outcome of the students’ thoughts. The preferred response for live synchronous is almost half of the total so it is equally beneficial, provides full expectation, and almost as effective as face to face.

A facilitated, precise, specificmethodology to determine the amount of total selenium in selenium-enriched biomass of Saccharomyces cerevisiae was designed and implementedusing high-performance liquid chromatography technique and UV detection (HPLC-UV). In this research study, a novel chromogenic reagent of 4, 5-Diamino-o-xylene (DAX) was evaluated for off-line pre-column selenium (IV) complexation. The complex of Se (IV) was eluted isocratically on BRISA LC2 C18 (250×0.46 mm, 5 µm, Teknokroma) analytical column. The mobile phase used was a degassed solution of deionized water and acetonitrile solution in a ratio of 50:50 (v/v) at a flow rate of 1.0 mL/min. UV-Vis detector at 340nm was used for complex detection. The method parameters were validated according tothe ICH Q2 (R1) requirements. The linearity was established over the dynamic range of 25-700 µg L-1 (r2=0.9994). The relative standard deviations (RSDs) were 1.1% for within-day determination (n=6) and 1.8% for between-day determination (n=6). The detection limit (LOD) and quantitation limit (LOQ) were found to be 8.0 and 25 μg L-1, respectively.

In this work, a new multi-class classification approach was employed in the QSAR model to assess chemical toxicity prediction through handling the imbalanced dataset as the critical preprocessing step in the training dataset. Various classifiers of the decision tree, K-NN, naive Bayes, kernelled naive Bayes, and SVM and two distinct acute aquatic toxicity datasets towards Daphnia Magna and Fathead Minnow Fish were used to evaluate the generality of the approach. The quantitative response (LC50) was discretized into ten bins. Imbalanced dataset classification leads to a high level of errors since the classifier tends to learn from the majority class more than the minority class. Each training dataset was specified by different weights related to the class population. These datasets were then bootstrapped based on their weights to convert the imbalanced dataset into a balanced one. This approach enhanced the accuracy of classification of material toxicity dramatically (up to 99%). Balanced dataset classification had high overall accuracy when correlated attributes were removed. Therefore, fewer attributes are sufficient to predict material toxicity.The overall accuracy improvement of the decision tree, K-NN, naive Bayes, kernelled naive Bayes, and SVM for the Daphnia Magna dataset after balancing the data set are 58.03%, 55.08%, 9.09%, 72.48%, and 53.05%, respectively.

In this work, a cobalt Schiff base complex (CoSB) immobilized at the surface of Fe3O4@SiO2‐NH2 nanoparticles was synthesized and characterized using different characterization techniques such as Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD). The prepared nanocomposite (Fe3O4@SiO2-NH2/CoSB) was applied as a sensitive modifier in carbon paste electrode (CPE) for simultaneous determination of acetaminophen (AC) and chlorpheniramine (CP). The Fe3O4@SiO2-NH2/CoSB/CPE exhibited good electrochemical response towards the detection of AC and CP. In addition, an excellent separation between the voltammetric signals for these analytes at the surface of modified electrode was observed.  The suggested methodwas effectively employed for concentration variation studies of a mixture containing these drugs. The dynamic linear ranges of 5.0 × 10−7 to1.0 × 10−3 M and 8.0 × 10−6 to 1.0 × 10−3 M with detection limits 4.0 × 10-7 M and 5.0 × 10-6 M (for S/N = 3) were achieved for AC and CP, respectively. The performance of the presented electrochemical nanosensor was assessed by quantifying the two drugs in spiked human blood serum and in tablets.