جستجوی مقالات مرتبط با کلیدواژه « degradation » در نشریات گروه « پزشکی »

Quercetin is a plant flavonoid known for its pharmacological activities, such as antioxidant, anti-inflammatory, and anti-cancer properties. However, there is limited information available regarding its potential toxicities. A previous study showed that quercetin can inhibit human ether-a-go-related gene (hERG, also named KCNH2) currents, which may lead to long QT syndrome, torsade de pointes (TdP), and even sudden cardiac death. This study aimed to investigate the effects of quercetin on hERG and its potential mechanism.

hERG currents and action potential duration (APD) were assessed using the patch clamp technique. Molecular docking was employed to elucidate the binding sites between quercetin and hERG. Transfection of wild-type or mutant plasmids was used to verify the results of molecular docking. Western blot was performed to determine the expression levels of hERG, transcription factor SP1, molecular chaperones HSP70 and HSP90, phosphorylated E3 ubiquitin ligase p-Nedd4-2, serum- and glucocorticoid-inducible kinase (SGK1), and phosphatidylinositol 3-kinase (PI3K). Immunoprecipitation was conducted to evaluate hERG ubiquitination.

Quercetin acutely blocked hERG current by binding to F656 amino acid residue, subsequently accelerating channel inactivation. Long-term incubation of quercetin accelerates Nedd4-2-mediated ubiquitination degradation of hERG channels by inhibiting the PI3K/SGK1 signaling pathway. Moreover, the APD of human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) is significantly prolonged by 30 μM quercetin.

Quercetin has a potential risk of proarrhythmia, which provided useful information for the usage and development of quercetin as a medication.

In this work, silver nanoparticles (Ag NPs) were synthesized by green tea plant extract as an easy, cost-effective, environmentally friendly, and reliable synthesis. The silver nanocomposite with different amounts of starch (0.5, 1, 1.5 g) were prepared. Then, the methylene blue (MB) dye degradation and the antibacterial activity of the nanocomposite were evaluated as an environmental challenge.

The samples were characterized using scanning electron microscope (SEM) for observation size and morphology, energy dispersive X-ray analysis (EDX) for determination elemental analysis, Fourier transform infrared spectroscopy (FTIR) for investigation functional groups, and X-ray diffraction analysis (XRD) for confirmation crystalline structure.  The catalytic properties of the synthesized samples were studied in MB degradation. 

The maximum degradation (more than 90%) was related to Ag NP with 0.5 g of starch. The antibacterial activity of Ag NPs and nanocomposites was investigated against Staphylococcus aureus (S. aureus) as Gram-positive and Pseudomonas aeruginosa (P. aeruginosa) as Gram-negative bacteria. The samples indicated inhibitory activity with suitable inhibition zone and were more effective against S. aureus as compared to P. aeruginosa. 

In general, the green synthesis of Ag NP-starch has good catalytic potential in MB degradation in an aqueous medium in a short time with high efficiency.

Metal screws are commonly used for fracture fixations. However, the high modulus of elasticity relative to bones and releasing metallic ions by the metal screw needed a second surgery to remove the implant after the healing period. Furthermore, the removal of metal screws following the healing of the bone is a serious problem that can lead to refracture due to the presence of holes in the screw. Bioresorbable screws can overcome most of the problems associated with metallic screws which motivated research on manufacturing nonmetallic screws.

In this study, three‑layer poly L‑lactic acid/bioactive glass composite screws were manufactured according to functionally graded material theory, by the forging process. All of the physical and chemical parameters in the manufacturing stages from making composite layers to the forging process were optimized to obtain suitable mechanical properties and durability off the screw in load‑bearing positions.

The tri‑layer composite screw with unidirectional, ±20° angled, and random fibers orientation from core to shell shows a flexural load of 661.5 ± 20.3 (N) with a decrease about 31% after 4‑week degradation. Furthermore, its pull‑out force was 1.8 ± 0.1 (N) which is considerably more than the degradable polymeric screws. Moreover, the integrity of the composite screws was maintained during the degradation process.

By optimizing the manufacturing process and composition of the composite and crystallinity, mechanical properties (flexural, torsion, and pull‑out) were improved and making it a perfect candidate for load‑bearing applications in orthopedic implants. Improving the fiber/matrix interface through the use of a coupling agent was also considered to preserve the initial mechanical properties. The manufactured screw is sufficiently robust enough to replace metals for orthopedic load‑bearing applications.

Different studies about the effects of mouthwashes on force reduction by elastomeric chains are reported in the literature. Hence, this review was done for the assessment of force degradation in the elastomeric chains in different mouthwash compositions. This study helps to improve the clinical performance of elastomeric chains used in orthodontics, reducing force degradation, and finally assisting clinicians in choosing better and more efficient methods for their treatments.

In this review article, an extensive search was performed in the electronic databases of Cochrane Library, Web of Science, PubMed, and Scopus from the year 1990–2020. No language restriction was considered and manually investigated the reference lists of all articles related to the title. Out of 450 obtained articles, 14 in vitro studies were chosen based on the inclusion criteria, and their quality was assessed using modified CONSORT. This systematic review was limited and written based on the Preferred Reporting Items for Systematic Reviews and Meta‑Analyses protocol.

Based on the results achieved, mouthwashes containing alcohol caused considerable force degradation in the elastomeric chains compared to the alcohol‑free ones and mouthwashes with fluoride caused lesser force degradation compared to other types.

Perchloroethylene (PCE) is one of the most well-known chlorinated organic compounds recently detected in aqueous environments. The presence of PCE in aquatic ecosystems has caused many health problems and environmental challenges. Therefore, its removal and treatment from aqueous environments are essential.

The electro-Fenton (EF) process was carried out in a cylindrical reactor containing 250 mL contaminated water with PCE. The effects of parameters, including solution pH (3-12), current density (2-10 mA cm-2), H2O2 concentration (20-70 µL H2O2 per 250 mL sample.), PCE concentration (5-50 mg L-1), and electrolysis time (1-15 min) on PCE degradation were investigated. The kinetics and radical’s scavenger of the EF process were examined to detect the exact mechanism of PCE degradation.

The degradation of the PCE of 98.1% was obtained in the optimum condition, including solution pH of 5, the current density of 8 mA cm-2, H2O2 concentration of 50 µL per 250 mL sample, PCE concentration of 15 mg L-1, and electrolysis time of 10 min. The kinetics studies of the EF process indicated that the obtained results were in satisfactory agreement with the first-order model (R2 = 0.9858, Kapp = 0.2822). Also, the addition of ethanol and tertiary butanol caused an inhibiting effect.

The EF process was effectively applied to degrade PCE from polluted water as an efficient technique.  The obtained results indicated that the generation of •OH throughout the EF process was the key mechanism that controlled the EF process.

In this study, alginate, magnetite, and hydroxyapatite were used to fabricate alginate-hydroxyapatite (Alg-Hap), alginate-Fe3O4 (Alg-Fe3O4), and alginate-magnetic hydroxyapatite (Alg-mHap) using ferric chloride (III) crosslinker to remove cefixime from an aqueous solution. FTIR, SEM, VSM, BET, and XRD tests were used to determine the functional groups, morphology, magnetization behavior, surface area, and crystallinity of catalysts, respectively. The optimal pH for the Fenton reaction was determined to be 3.3 for Alg-Hap and Alg-Fe3O4 catalysts and 4 for Alg-mHap catalysts. Increases in the concentration of hydrogen peroxide (1 to 3 mM) and the amount of catalyst (50 to 90 gr/L) increased the percentage of degradation to approximately 8% and 6%, respectively. The degradation efficiency of cefixime by using Alg-mHap as the best catalyst in the Fenton process was achieved 91%, at optimum condition (pH of 4, catalyst amount of 90 gr/L, initial cefixime concentration of 5 mg/L, H2O2 concentration of 3 mM within 90 min). Moreover, the second-order kinetic equation fits the experimental data for cefixime degradation for all three catalysts. Furthermore, not only did the catalysts display a negligible iron leaching (0.92 mg/L for Alg-mHap) but also after three consecutive cycles, the catalysts indicated long-term stability. Comparison between synthesized catalysts and other methods proved its effectiveness.

According to the results obtained thus far, ozone/magnetic copper ferrite nanoparticles (CuFe2O4 MNPs)/potassium hydrogen monopersulfate (KMPS) is capable of totally degrading 20 mg/L diazinon (DZN) with 6 mg/L ozone, 0.6 g/L KMPS, and 0.1 g/L MNPs at pH = 7 in 20 min. The experiments showed that the concentrations of KMPS and MNPs were more effective than ozone on the system efficiency. Moreover, high concentrations of KMPS and MNPs were not very effective in DZN degradation. Furthermore, the degradation efficiencies of diazinon at pHs 3, 4, 5, 6, 7, 8, 9, and 10 were 94%, 95.35%, 97.45%, 98.15%, 99.2%, 99.3%, 99.3%, and 100%, respectively. The pH of the solution was effective on the system so that in the range of 7 - 10, the system had high efficiency. Even within the range of 3 - 6, the pH had not been so plummeted, resulting in a high percentage of DZN degradation. Besides, MNPs could be utilized in the system for up to five cycles without any loss of catalytic activity. The degradation efficiency of diazinon was 99.2% in the first use and 92.1% in the fifth use. Also, the process efficiency was assessed in four real environments showing that agricultural drainage and urban wastewater with the degradation percentages of 79.1% and 77.3%, respectively, were better treated than the urban and river water with the percentages of 93% and 88.4%, respectively. With the determination of active agents in the reaction using the scavenging agents, it was recognized that sulfate radicals, hydroxyl radicals, superoxide, and singlet oxygen contributed to DZN degradation. By the way, ozone was advantageous to both singlet oxygen and superoxide in the degradation of diazinon.

Bioresorbable scaffolds have been advocated as the new generation in interventional cardiology because they could provide temporary scaffolds and then disappear with resorption. Although, the available stents in clinical trials exhibited biosafety, efficacy, no death, and no apparent thrombosis, Mg-substrate degradation on drug release has not been investigated.

Therefore, more research has been needed to legitimize the replacement of current stents with Mg-based stents. UV-Vis spectrophotometer, scanning electron microscope (SEM), X-ray diffraction (XRD), pH measurement, H₂ evolution, and corrosion tests determined the change in hybrid properties and drug release rate. 

The effect of Mg degradation on drug release from poly-L-lactide (PLLA) specimen was much higher than that of the L605/PLLA sample. Hydrogen evolution caused by magnesium degradation compelled everolimus out without significant PLLA decomposition during the first 100 days, while formation of Mg(OH)2 caused the PLLA to deform and crack. 

A combined mechanism of lattice/hole diffusion-dissolution governed the release of everolimus with the activation energies of 5.409 kJ/mol and 4.936 kJ/mol for the first 24 hr and diffusion coefficients 6.06×10-10 and 3.64×10-11cm2/s for the 50th to 100th days. Prolonged suppression of hyperplasia within the smooth muscle cells by hybrid stent insertion could bring about the cessation of restenosis.

The 1-Naphthol, one of the derivatives of naphthalene, is the most significant industrial chemical that is widely used in the production of dyes, pharmaceuticals, and biochemical processes.

In the present study, N, S-doped TiO2 thin film immobilized on silica sulfuric acid (SSA) glass microspheres (MS) was investigated as a novel high efficient photocatalyst. The N, S-doped TiO2 immobilized on SSA was fabricated using a simple modified sol–gel process. Its photocatalytic activities were then assessed using 1-naphthol solution in the presence of visible light. The physico-chemical properties of photocatalyst were characterized using energy-dispersive X-ray (EDX), scanning electron microscope (SEM) images and X-ray diffraction (XRD) pattern.

According to the obtained results, the optimal pH, time, concentration, and removal efficiency of 1-naphthol for N, S-doped TiO2 /SSA was 5, 50 minutes, 25mg/l and 92.12%.

The present study confirms the usability of the immobilized N, S-doped TiO2 on SSA glass MS as a novel, effective, and efficient technique for treatment of wastewater containing 1-naphthol under visible light.

Pectinase or pectinolyticenzyme is a complex enzyme with different catalytic units including polygalacturonase, pectin esterase and pectin lyase to degrade pectin polymers into different end products. The pectinase with degrading capability of pectin can be utilized in various industrial applications, such as clarification of fruits and vegetable juices, degumming of plant bast fibers, textile industries for removing non-cellulosic impurities, papermaking industries, wine clarification, coffee and tea fermentation, wastewater treatment, as well as, it is also used for the isolation of protoplasm in plant science research. Pectin derived oligosaccharides (POS) produced by pectinase are considered as prebiotic molecules. However, the low operational stability in harsh industrial conditions confines the utilization of pectinase in industrial processes. Immobilization is the technique, which not only enhanced the stability of pectinase, but also, made the enzyme reusable for continuous industrial processes. The current review shares information about the pectinase and how the immobilization technology can enhance the industrial application of pectinase. Furthermore, various supports such as sodium alginate, agar-agar, polyacrylamide, aminated silica gel, nanocomposite microspheres, silica coated chitosan, nylon-6, porous glass etc. have been tested for the immobilization of pectinase through different methods, including entrapment, binding to a support and enzyme crosslinking.

Comparing to the chemical and physical techniques, biosynthesis of nanoparticles is being facilitated due to its nontoxic and economically feasible availability. In this present study, plant-mediated silver nanoparticles (AgNPs) were synthesized using the fruit extract of Sonneratia apetala from the silver nitrate (AgNO3) solution. Among different physiological conditions, effect of reaction time was investigated during the AgNPs synthesis. Surface Plasmon Resonance (SPR) characterization was conducted for verifying the nanoparticles size and morphology. A distinct band centered around 400-480 nm in the UV-Visible spectroscopy represented the formation of AgNPs. FTIR spectroscopy revealed that –OH group may play important role for the reduction of Ag+ to AgNPs. XRD revels the face-centered cubic geometry of AgNPs. AFM image analysis helped to find out the shape of the synthesized AgNPs is sphereical. The efficiency of AgNPs as a promising catalyst through electron transfer in the degradation of methyl orange and methyl red was investigated. This catalytic activity of AgNPs can be used to synthesis different chemical intermediates and organic transformations.

The combination of chlorthalidone and benidipine was used to manage hypertension. The mixture of chlorthalidone and benidipine in tablet dosage form has not been previously determined by any method. A stability indicating HPLC method was developed for the simultaneous determination of benidipine and chlorthalidone in bulk and tablets.

Chromatographic separation was accomplished in a reverse phase system using an isocratic elution with a mobile phase composed of methanol-0.1M dipotassium hydrogen phosphate buffer (40:60, v/v), at 1 ml/min flow rate. The photodiode array (PDA) detector set at 260 nm was used to detect and quantify benidipine and chlorthalidone. Benidipine and chlorthalidone tablet samples were subjected to degradation under acid, neutral, alkali, thermal, photo and oxidative. The proposed method was effectively adapted to quantify benidipine and chlorthalidone in the combined tablet formulation.

The elution times for benidipine and chlorthalidone were approximately 4.573 min and 6.422 min, respectively. The method was validated within a concentration range of 2 - 6 μg/ml (R2 = 0.9997) for benidipine and 6.25 - 18.75 μg/ml (R2 = 0.9998) for chlorthalidone. Adequate results were obtained for precision (RSD% = 0.106% for benidipine and RSD% = 0.031% for chlorthalidone) and accuracy (99.95 - 100.25 % mean recovery for benidipine and 99.60 - 99.63% mean recovery for chlorthalidone). Robustness has also been found to be acceptable. During the degradation study, interference was not noticed in the analysis of studied drugs.

The findings demonstrated that the method could be useful for determination of the selected drug combination in routine analysis.

In this study, we investigate the problems and obstacles of implementing the risk-based auditing in Iran. We set four hypotheses and used questionnaire containing 45 questions to collect the required data. The questionnaires were distributed between Iranian certified public accountants who were partners or directors of audit firms and audit organizations member of Iranian certified public accountant institute. To determine the validity of the research questionnaire limited number of questionnaires distributed between small sample of respondents and their views taken into account. The Cronbach’s alpha test is used to measure reliability of the questionnaire. The results of this study indicated that, lack of the theoretical foundations and regulations of risk-based auditing in Iran, structure and function of auditors and audit firms and factors related to the clients are the obstacles and limitations on implementation of risk-based auditing in Iran Then the most important factors prioritized using fuzzy hierarchy analysis. For this reason, a questionnaire was developed with 16 factors from approved hypotheses. Results revealed that related factors with the auditors and unfamiliarity of auditors with IT and lack of educational resources were the most important obstacles and limitations on implementation of the risk-based auditing in Iran.

In the present study, magnesium oxide/granular activated carbon (MgO/GAC) composite as a catalyst was synthesized using the sol-gel method and its catalytic potential was investigated in the presence of ultraviolet (UV) irradiation for the removal of cephalexin (CLX) in a batch mode reactor. Then, the characterization of the MgO/GAC composite was determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Next, the effect of operational parameters was evaluated, including the pH of the solution (3-11), the dosage of composite (1-6 g/L), initial CLX concentration (20-100 mg/L), and contact time (10-60 minutes). The maximum CLX degradation with an initial concentration of 20 mg/L was as high as 98% at pH=3, 4 g/L of MgO/GAC composite with UV irradiation within 60-minute contact time. In addition, the removal process of CLX could be described by the pseudofirst-order kinetic. Further, the chemical oxygen demand (COD) and total organic carbon (TOC) removal rate were 78% and, 62.3% in optimum conditions, respectively. The results indicated that the UV/MgO/GAC hybrid photocatalytic process can be considered as an efficient alternative for treating the wastewater containing CLX.