Experimental and theoretical insights into the corrosion inhibition activity of novel Schiff bases for aluminum alloy in acidic medium

Three novel Schiff bases, namely N-(4-((4-((phenylimino)methyl)phenoxy)methoxy)benzylidene)benzenamine (UA), N-(3-methoxy-4-((2-methoxy-4-((phenylimino)methyl)phenoxy)methoxy)benzylidene)benzenamine (UB), and N-(3-ethyl-4-((2-ethyl-4-((phenylimino)methyl)phenoxy)methoxy)benzylidene)benzenamine (UC), were synthesized and their structures were elucidated through diverse spectroscopic techniques such as FT-IR, GC-MS, ¹H NMR and ¹³C NMR. The corrosion inhibition effect of these Schiff bases on aluminum alloy AA2219-T6 in acidic medium was explored using weight loss, Tafel polarization, and electrochemical impedance spectroscopy. Theoretical quantum chemical calculations using density functional theory were employed to determine the adsorption site. It was found that inhibition efficiencies increase with an increase in the inhibitor concentration. Tafel plots showed that these Schiff bases function as mixed inhibitors. Adsorption of the Schiff bases on aluminum followed the Langmuir adsorption isotherm and the value of showed a dominant chemical mechanism. FT-IR and SEM techniques were used to investigate the surface morphology. The compounds showed a substantial corrosion inhibition for aluminum alloy in 0.1 M HCl at 298 K. UB and UC exhibited superior anticorrosion efficiency compared to UA originating from the electron-donating methoxy and ethoxy group substitutions, respectively. There was found to be good correlation between molecular structure and inhibition efficiencies.

Novel Schiff bases characterized through spectroscopic techniques and used as anticorrosive agents for aluminium alloy acidic medium. Electrochemical techniques and DFT studies were used to study inhibition effect and molecular interactions.     

The speciation of inorganic arsenic in soil and vegetables irrigated with treated municipal wastewater

In this research, an environmental friendly, green and efficient sample preparation method using vortex-assisted microextraction based on a deep eutectic solvent (VAME-DES) followed by graphite furnace atomic absorption spectrometry (GFAAS) was developed for the preconcentration and determination of As(iii)/As(v) and total inorganic arsenic in soil and vegetables irrigated with treated municipal wastewater from Tehran and Kermanshah, Iran. In the proposed method, a novel DES, characterized by its low density, was prepared by mixing choline chloride and citric acid monohydrate at a molar ratio of 1 : 1. Under optimal conditions, the proposed method enabled the achievement of a good enrichment factor of 175. The calibration graph was linear in the range of 0.3–100 μg kg⁻¹ and the limit of detection (LOD) was 0.10 μg kg⁻¹. The repeatability and reproducibility of the method based on seven replicate measurements of 50 μg kg⁻¹ As(iii) in analysed samples were 4.2% and 6.5, respectively. The relative recoveries from soil and vegetables that were spiked with different levels of As(iii) and As(v) were 94.2–104.3 and 91.0–107.0%, respectively. The main advantage of the proposed method is the use of a non-toxic and non-volatile DES instead of volatile organic solvents. The accuracy of the proposed procedure was also assessed by the speciation of arsenic in two standard reference materials ({"type":"entrez-protein","attrs":{"text":"GBW10014","term_id":"1450827424","term_text":"GBW10014"}}GBW10014 cabbage and {"type":"entrez-protein","attrs":{"text":"GBW10015","term_id":"1450827425","term_text":"GBW10015"}}GBW10015 spinach). The extraction methodology is simple, rapid, cheap and green, since only small amounts of non-toxic solvents are necessary.

An efficient method using vortex-assisted microextraction based on a deep eutectic solvent followed by graphite furnace atomic absorption spectrometry was developed for the determination of arsenic species in soil and vegetables irrigated with treated wastewater.     

Concrete by Preplaced Aggregate Method Using Silica Fume and Polypropylene Fibres

Preplaced aggregate concrete (PAC) is prepared in two steps, with the coarse aggregate being initially laid down in the formwork, after which a specialised grout is injected into it. To enhance the properties of concrete and to reduce the emission of CO₂ produced during the production of cement, supplementary cementitious materials (SCMs) are used to partially substitute ordinary Portland cement (OPC). In this study, 100 mm × 200 mm (diameter x height) PAC cylinders were cast with 10 per cent of cement being substituted with silica fume; along with that, 1.5% dosage of Macro polypropylene fibres were also introduced into the coarse aggregate matrix. Compressive strength test, splitting tensile strength test, mass loss at 250 °C, and compressive strength at 250 °C were performed on the samples. PAC samples with 10% of cement replaced with Silica Fume (SPAC) were used as control samples. The primary objective of this study was to observe the effect of the addition of Polypropylene fibres to PAC having Silica fume as SCM (FRPAC). The aforementioned tests showed that FRPAC had a lower compressive strength than that of the control mix (SPAC). FRPAC had greater tensile strength than that of NPAC and SPAC. Mass loss at 250 °C was greater in SPAC compared to FRPAC. The compressive strength loss at 250 °C was significantly greater in FRPAC compared to SPAC. FRPAC exhibited a greater strain for the applied stress, and their stress-strain curve showed that FRPAC was more ductile than SPAC.     

Synthesis of Ni–Ag–ZnO solid solution nanoparticles for photoreduction and antimicrobial applications

ZnO is one of the most promising and efficient semiconductor materials for various light-harvesting applications. Herein, we reported the tuning of optical properties of ZnO nanoparticles (NPs) by co-incorporation of Ni and Ag ions in the ZnO lattice. A sonochemical approach was used to synthesize pure ZnO NPs, Ni–ZnO, Ag–ZnO and Ag/Ni–ZnO with different concentrations of Ni and Ag (0.5%, 2%, 4%, 8%, and 15%) and Ni doped Ag–ZnO solid solutions with 0.25%, 0.5%, and 5% Ni ions. The as-synthesized Ni–Ag–ZnO solid solution NPs were characterized by powdered X-ray diffraction (pXRD), FT-IR spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), UV-vis (UV) spectroscopy, and photoluminescence (PL) spectroscopy. Ni–Ag co-incorporation into a ZnO lattice reduces charge recombination by inducing charge trap states between the valence and conduction bands of ZnO and interfacial transfer of electrons. The Ni doped Ag–ZnO solid solution NPs have shown superior 4-nitrophenol reduction compared to pure ZnO NPs which do not show this reaction. Furthermore, a methylene blue (MB) clock reaction was also performed. Antibacterial activity against E. coli and S. aureus has inhibited the growth pattern of both strains depending on the concentration of catalysts.

The synergic effect of Ni and Ag in Ni–Ag–ZnO solid solutions has tuned the optoelectronic properties of ZnO for photoreduction reactions.     

Review on Graphene-, Graphene Oxide-, Reduced Graphene Oxide-Based Flexible Composites: From Fabrication to Applications

In the new era of modern flexible and bendable technology, graphene-based materials have attracted great attention. The excellent electrical, mechanical, and optical properties of graphene as well as the ease of functionalization of its derivates have enabled graphene to become an attractive candidate for the construction of flexible devices. This paper provides a comprehensive review about the most recent progress in the synthesis and applications of graphene-based composites. Composite materials based on graphene, graphene oxide (GO), and reduced graphene oxide (rGO), as well as conducting polymers, metal matrices, carbon–carbon matrices, and natural fibers have potential application in energy-harvesting systems, clean-energy storage devices, and wearable and portable electronics owing to their superior mechanical strength, conductivity, and extraordinary thermal stability. Additionally, the difficulties and challenges in the current development of graphene are summarized and indicated. This review provides a comprehensive and useful database for further innovation of graphene-based composite materials.     

Evaluation of Mast Cell Density using CD117 antibody and Microvessel Density Using CD34 Antibody in Different Grades of Oral Squamous Cell Carcinoma

Objective: To compare mast cell and microvessel densities among histologic grades of oral squamous cell carcinoma. Setting: Armed Forces Institute of Pathology. Materials and Methods: A total of 60 specimens of OSCC comprising 20 each of well, moderately and poorly differentiated were evaluated. Immunohistochemical analysis was performed to measure MCD and MVD by applying monoclonal CD117 antibody and monoclonal CD34 antibody, on formalin fixed and paraffin embedded sections. ANOVA and Post Hoc Tukey test was employed to assess the densities and to compare the differences between different grades of OSCC. A p-value     

Drug-prescribing patterns during pregnancy in the tertiary care hospitals of Pakistan: a cross sectional study

Background

Low birth weight (LBW) is considered as a major multifaceted public health concern. Seventy-two percent of LBW infants are born in Asia. An estimation of 8% LBW infants has been reported for Eastern Mediterranean region including Iran. This study investigated contributory factors of LBW in singleton term births in Tehran, Iran. Tehran is a multicultural metropolitan area and a sample from the general population in Tehran could be regarded as a representative sample of urban population in Iran.

Methods

This was a retrospective study using data from 15 university maternity hospitals in Tehran, Iran. Data on all singleton term births in these hospitals were extracted from case records during a one calendar year. Study variables included: maternal age, maternal educational level, history of LBW deliveries, history of preterm labor, cigarette smoking during pregnancy, number of parities, chronic diseases and residential area (Tehran versus suburbs of Tehran). In order to examine the relationship between LBW and demographic and reproductive variables the adjusted logistic regression analysis was performed.

Results

In all, data for 3734 term pregnancies were extracted. The mean age of women was 25.7 (SD = 5.3) years and 5.2% of term births were LBW. In addition to association between LBW and maternal age, significant risk factors for LBW were: history of LBW deliveries [adjusted odds ratio (OR) = 2.53, 95% confidence interval (CI) = 1.06–6.03], smoking during pregnancy (OR = 4.64, 95% CI = 1.97–10.95) and chronic diseases (OR for hypertension = 3.70, 95% CI = 2.25–6.06, OR for others = 2.04, 95% CI = 1.09–3.83).

Conclusion

The findings indicate that in addition to maternal age, history of LBW deliveries; smoking during pregnancy and chronic diseases are significant determinants of LBW in this population. This is consistent with national and international findings indicating that maternal variables and risk behaviors during pregnancy play important roles on LBW.     

Initial experience with laparoscopic bypass for upper gastrointestinal malignancy: a new option for palliation of patients with advanced upper gastrointestinal tumors

BACKGROUND: The majority of patients with upper gastrointestinal (UGI) tract malignancy present at a stage where cure of disease is not possible. The aim of treatment in these patients is effective palliation. Various interventions have been described for the palliation of biliary and gastric outlet obstruction including open surgery, endoscopic and transparietal stent placement. Laparoscopic bypass appears to have the advantage of decreased postoperative pain and shorter hospital stay as well as offer effective palliation. The aim of this study was to assess the safety and efficacy of laparoscopic bypass in patients with incurable UGI tract malignancy. PATIENTS AND METHODS: Between August 2000 and April 2002 laparoscopic gastric and biliary bypass concurrently or alone was attempted in 19 consecutive patients with unresectable carcinoma of the head of the pancreas, adenocarcinoma of the stomach, cholangiocarcinoma of the distal common bile duct, or adenocarcinoma of the duodenum. The operative time, length of postoperative stay, complications, and the effectiveness of the procedure in terms of the ability to sustain oral nutrition and or the relief of obstructive jaundice were recorded and used as outcome measures. RESULTS: Laparoscopic bypass was successful in 18 out of 19 cases. The mean operative time for a single bypass was 164 minutes while the average postoperative hospital stay was 11 days. All patients were able to sustain oral nutrition during the course of their hospital stay and or had effective relief from their obstructive jaundice. Two patients died from procedure unrelated causes within 30 days of the operation. CONCLUSION: Laparoscopic bypass appears to be a safe and effective means of palliation for patients with unresectable UGI tract tumors and should replace open surgical palliation in this group of patients.     

Results of the national pilot screening program for venous disease by the American Venous Forum

OBJECTIVE: This report describes the pilot of a free comprehensive national screening program for venous disease. METHODS: The screening process consisted of a venous thromboembolism (VTE) risk assessment, abbreviated duplex examination for venous obstruction and reflux, inspection for signs of chronic venous insufficiency (CVI), and an exit interview. Physicians coordinating the screenings were members of the American Venous Forum. RESULTS: Seventeen institutions screened 476 people (mean, 28 per site; range, 6 to 71). Mean age was 60 years (range, 40 to 91 years), with 78% women and 68% with a body mass index of > or =25. If placed in a situation conducive for VTE, 22 participants (5%) were low risk, 87 (18%) were moderate risk, 186 (39%) were high risk, and 179 (38%) were at very high risk. In 26 people (6%), one or more segments had venous obstruction, and 190 (40%) had one or more segments of venous reflux in the lower extremities. Varicose veins were present in 32%, edema without skin changes in 11%, skin changes attributable to venous disease in 8%, and healed or active venous stasis ulcer in 1.3% (CEAP classification 2, 3, 4, 5, and 6, respectively). Increasing age and increasing deep venous thrombosis risk score significantly correlated with increasing clinical classification, r = 0.09, P = .04, and r = 0.16, P = .0004, respectively. Those participants with reflux in one or more segments were significantly more likely to have a higher clinical classification compared with those with no reflux (P = .0001). CONCLUSION: The first comprehensive national screening for venous disease was performed. Participants were informed of their risk for VTE if placed in a situation conducive to VTE, screened for evidence of obstruction, reflux, and CVI, and empowered to share their results with their primary care provider.     

Therapeutic Efficacy of Neurostimulation for Depression: Techniques,Current Modalities,and Future Challenges

Depression is the most prevalent debilitating mental illness; it is characterized as a disorder of mood, cognitive function, and neurovegetative function. About one in ten individuals experience depression at some stage of their lives. Antidepressant drugs are used to reduce the symptoms but relapse occurs in ~20% of patients. However, alternate therapies like brain stimulation techniques have shown promising results in this regard. This review covers the brain stimulation techniques electroconvulsive therapy, transcranial direct current stimulation, repetitive transcranial magnetic stimulation, vagus nerve stimulation, and deep brain stimulation, which are used as alternatives to antidepressant drugs, and elucidates their research and clinical outcomes.