Fracture load in double keyhole notch PLA-Cu2O nanocomposites manufactured via compression molding and 3D printing: An experimental and numerical study

Polylactic acid (PLA) polymer has garnered significant attention due to its biocompatibility. The incorporation of copper oxide (Cu2O) nanoparticles into this polymer is expected to enhance its antibacterial, electrical, and thermal properties. This modification can potentially improve the performance of PLA in the fields of prosthetics manufacturing or printed circuit fabrication. However, the current research is rather focused on the mechanical properties of the PLA-Cu2O nanocomposites. This research is thus aimed to analyze PLA-Cu2O (97-3 wt%) nanocomposites with a double keyhole notch configuration both experimentally and numerically. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray mapping of elemental distribution(X-map), and thermogravimetric analysis (TGA) were employed to explore the morphology, crystallinity, homogeneity, purity, and thermal stability of the nanocomposite. The specimens were fabricated through two different processes: the classical method of compression molding and the innovative method of 3D printing. The results revealed the superior mechanical performance of the 3D-printed nanocomposite at a 0° raster angle, while the mechanical properties gradually decreased for raster angles of 45° and 90°. The experimental test also indicated a decline in the maximum fracture load of specimens with a double keyhole notch and constant notch inclination angle by raising the notch radius. This behavior was also observed by increasing the notch inclination angle at constant notch radius. The numerical results were similar to the experimental findings. Moreover, the nanocomposite manufactured through the classical method exhibited higher critical fracture load compared to their 3D-printed counterparts with the same geometry.

Highly efficient, bioactive, and bifunctional sorbent p-n-p visible light heterogeneous photocatalyst utilizing ultra-fine ZnS nanoparticles embedded in a polymeric nanocomposite

This study reports the successful synthesis of a ZnS@GO@Pani polymeric nanocomposite (NC) via chemical polymerization. The product was used for simultaneous photocatalytic degradation-adsorption of malachite green (MG), a carcinogenic and widely used dye. The physicochemical properties of the prepared NC were characterized by various techniques. Morphological and XRD results confirmed the fine size of ZnS nanoparticles (NPs) with an approximate mean size of 5 nm, uniformly distributed within the polymeric matrix. For comparative purposes, photocatalytic dye degradation-adsorption of this nanohybrid was explored both in the dark and under natural light. It was observed that 0.1 g of the ternary NC in MG aqueous solution (20 ppm) leads to dye adsorption within 15 minutes with an efficiency of 70% under dark conditions. Also, MG removal efficiency of up to 90% was achieved in 15 minutes under natural light owing to integrated photocatalytic degradation-adsorption mechanisms. Adsorption isotherm studies were performed considering Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) models. The results showed that the Freundlich isotherm with R 2 = 0.988 is well consistent with the experimental data. Integrated photocatalytic degradation-adsorption kinetics were modeled with pseudo-first-order (PFO) and pseudo-second-order (PSO) models where PSO with R 2 = 0.999 best fitted the data, implying the predominant role of chemical adsorption in the dye removal process. Antibacterial tests revealed superior antibacterial activity of the prepared ZnS@GO@Pani NC against both Gram-negative and Gram-positive bacteria, demonstrating the remarkable synergistic effect of ZnS NPs embedded in the GO@Pani matrix. Accordingly, the prepared NC could be regarded as a promising candidate for wastewater treatment applications. The leaching and regeneration studies also confirmed that the prepared NC is a non-toxic dye removal agent with good reusability.

Selective reduction of azoarenes into arylamine(s) by aluminium / NH4Br under sonic conditions

Azoarenes, both symmetrical and unsymmetrical are cleaved into arylamine/s by aluminium metal and ammonium bromide in refluxing methanol with high yields. The rate of the reaction is greatly accelerated by irradiating at 35 kHz in a sonic bath maintained at 25 °C.

Nuclear magnetic resonance, vibrational spectroscopic studies, physico-chemical properties and computational calculations on (nitrophenyl) octahydroquinolindiones by DFT method

In the present study, 2'-nitrophenyloctahydroquinolinedione and its 3'-nitrophenyl isomer were synthesized and characterized by FT-IR, FT-Raman, (1)H NMR and (13)C NMR spectroscopy. The molecular geometry, vibrational frequencies, (1)H and (13)C NMR chemical shift values of the synthesized compounds in the ground state have been calculated by using the density functional theory (DFT) method with the 6-311++G (d,p) basis set and compared with the experimental data. The complete vibrational assignments of wave numbers were made on the basis of potential energy distribution using GAR2PED programme. Isotropic chemical shifts for (1)H and (13)C NMR were calculated using gauge-invariant atomic orbital (GIAO) method. The experimental vibrational frequencies, (1)H and (13)C NMR chemical shift values were found to be in good agreement with the theoretical values. On the basis of vibrational analysis, molecular electrostatic potential and the standard thermodynamic functions have been investigated.

Silica chloride catalyzed efficient route to novel 1-amidoalkyl-2-naphthylamines under sonic condition in water

A one-pot three-component condensation of an aldehyde, 2-naphthylamine, and acetamide has been achieved by sonication at 35 kHz. The reaction is catalysed by silica chloride in aqueous medium. This protocol afforded corresponding 1-amidoalkyl-2-naphthylamines in shorter reaction durations, and in high yields. The method involves simple work-up procedure, and avoids use of hazardous reagents.

Ultrasound assisted synthesis of tetrahydrobenzo[c]xanthene-11-ones using CAN as catalyst

Tetrahydrobenzo[c]xanthenes-11-ones was synthesized by a three component reaction of α-naphthol, aromatic aldehyde and dimedone. Ceric ammonium nitrate acts as a suitable eco-friendly catalyst for this method. Shorter reaction duration, mild reaction condition and low cost make this protocol more effective.

Glycine catalyzed convenient synthesis of 2-amino-4H-chromenes in aqueous medium under sonic condition

A one-pot three-component condensation of an aldehyde, malononitrile, and resorcinol has been achieved by ultrasound method. The reaction has been catalyzed by glycine in aqueous medium. This protocol afforded corresponding 2-amino-4H-chromenes in shorter reaction times, high yields and simple work-up procedures with the green aspects by avoiding toxic reagents.

An efficient and simple approach for the synthesis of pyranopyrazoles using imidazole (catalytic) in aqueous medium, and the vibrational spectroscopic studies on 6-amino-4-(4'-methoxyphenyl)-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazole using density functional theory

We describe a one-pot four component synthesis of pyranopyroles from aryl aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of catalytic amounts of an organocatalyst imidazole in water as medium. A plausible mechanism for the formation of imidazole catalyzed pyranopyrazoles has been envisaged. This method is rapid, simple, provides products in good yield, and is eco-friendly. In addition, based on the optimized geometry, the frequency and intensity of the vibrational bands of 6-amino-4-(4'-methoxyphenyl)-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazole were obtained by the density functional theory (DFT) calculations using 6-31G(d,p) basis set. The vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement.

An efficient sonochemical oxidation of benzyl alcohols into benzaldehydes by FeCl3/HNO3 in acetone

Sonochemical oxidation of benzyl alcohols into corresponding aldehydes by FeCl(3)/HNO(3) in acetone at room temperature has been reported. All substrates give good yield of the products within 10-25 min. The reaction of selected substrates were also studied under reflux and at the room temperature. Further, various Lewis acids were used to evaluate their catalytic efficacy.

Cavitational chemistry: a mild and efficient multi-component synthesis of amidoalkyl-2-naphthols using reusable silica chloride as catalyst under sonic conditions

An efficient and direct procedure for the synthesis of amidoalkyl-2-naphthol derivatives has been described. The process employs a three-component cyclocondensation reaction in one-pot using β-naphthol, aromatic aldehyde and acetamide or benzamide in the presence of silica chloride accelerated by ultrasound giving the product in excellent yield in very short duration.

Ultrasound assisted synthesis of delta-chloroesters from tetrahydrofuran and acyl chlorides in the presence of catalytic zinc dust

Sonication of acyl chlorides and dry tetrahydrofuran (THF) in the presence of catalytic amounts of zinc dust at 35 kHz gives delta-chloroesters in high yields.

A comparative study and development of an improved method for the reduction of nitroarenes into arylamines by Al/NH4X (X=Cl, Br, I) in methanol under ultrasonic conditions

Nitroarenes were shown by us earlier to undergo reduction when treated with Al/NH4Cl in methanol under sonic conditions to give anilines in high yields [D. Nagaraja, M.A. Pasha, Tetrahedron Lett. 40 (1999) 7855]. Now, a comparative study has been carried out and an efficient and improved procedure for this reduction by using Al/NH4X (X=Cl, Br, I) is reported. A plausible mechanism of the reaction is envisaged.

Ultrasound promoted regioselective synthesis of beta-iodoethers from olefin-I2-alcohol

Regioselective synthesis of beta-iodoethers in high yields by sonicating alkene and alcohol in the presence of iodine in a bath at 35 kHz is reported.

Reduction of arylnitro compounds to azoarenes and/or arylamines by Al/NaOH in methanol under ultrasonic conditions

Arylnitro compounds are reduced to the corresponding azoarenes and/or arylamines by aluminium metal in the presence of sodium hydroxide in methanol in high yields under influence of power ultrasound (35 kHz) at 25 degrees C.

Association between blood levels of lead, blood pressure and risk of diabetes and heart disease in workers

BACKGROUND

Previous studies have supported the association between high levels of blood lead levels (BLL) and elevated blood pressure. In addition, significant correlations between BLL and a variety of risk factors for blood pressure and diabetes mellitus have been well-established.

OBJECTIVE

To examine the relationship between BLL, blood pressure and diabetes as well as other selected social and biochemical factors, among workers in the United Arab Emirates (UAE).

METHODS

This comparative study included 110 industrial workers (exposed to lead in the workplace) and 110 non-industrial workers (not exposed); all were recruited in the city of Al-Ain, Abu-Dhabi Emirate, UAE and the groups were evenly matched for age, gender and nationality.

RESULTS

The industrial workers had a significantly higher mean of BLL (median 81 and geometric mean (GM) 62 microg/dl) than did non-industrial workers (median 11 and GM 13 microg/dl). In the present study, the lead-exposed group also had significantly higher blood lead levels, body-mass index (BMI), systolic and diastolic blood pressures, fasting blood glucose and plasma levels of total cholesterol, lactate dehydrogenase and uric acid than did the non-exposed group. Furthermore a significant correlation between BLL and systolic blood pressure was observed.

CONCLUSION

The study supports the hypothesis of a positive association between lead exposure, high blood pressure and risk of diabetes and heart disease.

Occupational lead exposure and amino acid profiles and liver function tests in industrial workers

The aim of the present study is to determine the effect of blood lead on the plasma levels of amino acids and serum liver enzymes in industrial workers in United Arab Emirates (UAE). This comparison study consisted of 100 industrial workers (exposed) and 100 non-industrial workers (non-exposed), matched for age, sex and nationality selected from Al-Ain, Abu-Dhabi Emirates. Industrial workers had higher proportion (19%) of smokers than non-industrial workers (11%) which was not considered to be statistically significantly different. Industrial workers had significantly higher mean of blood lead level (77.5 +/- 42.8 miccrog x dl(-1)) than non-industrial workers (19.8 +/- 12.3 microg x dl(-1)). The amino acid analysis showed higher values among industrial than non-industrial workers for histidine, isoleucine, leucine, threonine, lysine, valine, methionine and arginine (essential amino acids, (p<0.0001). Ornithine, taurine, glutamic acid, serine, glycine, proline and alanine (non-essential amino acids) showed significantly higher values in industrial when compared with the non-industrial workers (p<0.0001). Plasma liver function test, cardiac enzymes and renal function test were carried out on industrial and non-industrial workers. The results revealed alkaline phosphatase (p=0.012) and lactate dehydrogenase (p=0.029) were significantly higher in industrial than in non-industrial workers. On the basis of this study, it can be concluded that a substantial difference in amino acid profiles, blood lead and LFT between exposed and non-exposed was found. These results might be related to lead exposure and might have affects on the kidneys or liver.

Randomized, controlled study of low-dose 5-fluorouracil in primary trabeculectomy

PURPOSE

To report a randomized clinical trial of postoperative subconjunctival injections of low-dose 5-fluorouracil in patients undergoing primary trabeculectomy.

METHODS

In a prospective, randomized clinical trial, 40 eyes of 40 patients were randomized to the low-dose 5-fluorouracil group and received three subconjunctival injections of 5 mg each over 11 postoperative days, and 40 eyes of 40 patients were randomized to trabeculectomy without 5-fluorouracil.

RESULTS

Mean (+/-SD) preoperative and 1-year postoperative intraocular pressures in the 5-fluorouracil group were 26.9 (+/-9.5) and 15.3 (+/-5.8) mm Hg, respectively. In the control group these were 25.9 (+/-8.1) mm Hg, and 15.8 (+/-5.1) mm Hg, respectively. The patients who received 5-fluorouracil had a mean reduction in intraocular pressure of 11.5 (+/-9.1) mm Hg at a median follow-up of 52.3 weeks. The control group had a mean reduction in intraocular pressure of 10.2 (+/-8.7) mm Hg at a median follow-up of 52.6 weeks. These differences were not statistically significant.

CONCLUSIONS

Three postoperative subconjunctival 5-fluorouracil injections of 5 mg each after trabeculectomy in eyes at low risk for failure had no statistically or clinically significant effect on reduction of intraocular pressure with 1-year follow-up. Enhancement of success in this group of patients may require a larger total dose of 5-fluorouracil.

Respiratory symptoms, skin disorders and serum IgE levels in farm workers

The aim of this study is to evaluate the prevalence of dermo-respiratory symptoms from lung-function spirometer values and serum IgE levels in farmers who have been exposed to pesticides in the United Arab Emirates (E.A.U.). The study was a comparison of 98 farmers with 98 non-farmers, the two groups were equivalent in age, sex and selected regions--the town of Al-Ain and in the Emirates of Dubai, Sharjah and Fujairah. Most of the farmers were illiterate or poorly educated (p < 0.0001). Most lived in prefabricated houses (50.5%). Use of chemical substances (70.9%) and a mixture of pesticides by the farmers (60.2%) was very high. The results revealed that the farmers had a very high prevalence of chronic dermo-respiratory symptoms. These differences are statistically significant when compared with the reference group, particularly for the following symptoms: cough (p < 0.003), pharyngitis (p < 0.0003), bronchitis (p < 0.02), asthma (p < 0.008), respiratory insufficiency (p < 0.006), pneumonia (p < 0.003), dyspnea (p < 0.006), nasal catarrh (p < 0.001), sinusitis (p < 0.05), pharyngeal irritation (p < 0.01), nasal irritation (dryness, sneezing and secretions) (p < 0.005), ocular irritation (p < 0.05), cutaneous pruritus (p < 0.002), and contact dermatitis (p < 0.02). The spirometer tests (all parameters together) measured in the farmers were significantly reduced by comparison with the reference group. In conclusion, the authors suggest that a high prevalence of dermo-respiratory symptoms, supported by reduced spirometer tests and high serum IgE, is associated with exposure to pesticides. These results are clearly useful for establishment of work-related reduced exposure in the future.

A study of the coagulant activity of Indian green pit viper venom

Indian green pit viper venom was studied for its coagulant activity. It was observed that the venom contained a significant amount of coagulant activity, which was similar to thrombin in its action on plasma as well as on fibrinogen. The physicochemical properties studied suggested that the venom coagulant activity lacked both platelet aggregating and factor XIII activating properties. Unlike thrombin, the activity was retained in the presence of heparin and at high temperatures. The activity was inhibited by Diisopropyl fluorophosphate and phenyl methyl sulphonyl fluoride, indicating that it was a serine esterase.