-
دسترسی آزاد مقاله
1 - Optimized Purification of Free Amino Acids from Molasses by Nanofiltration Membrane
M. Varaee M. Honarvar M. H. Eikani M. R. Omidkhah N. MoorakiIn this research, nanofiltration was utilized to purify free amino acids (AAs) from sugar and colloids of sugar cane molasses (SCM) and sugar beet molasses (SBM) based on their molecular weight. The impact of temperature (30-50˚C), pressure (2-7 bar), and pH (2-11) in o چکیده کاملIn this research, nanofiltration was utilized to purify free amino acids (AAs) from sugar and colloids of sugar cane molasses (SCM) and sugar beet molasses (SBM) based on their molecular weight. The impact of temperature (30-50˚C), pressure (2-7 bar), and pH (2-11) in optimizing the purification condition was evaluated using the response surface methodology. The SCM and SBM purification results revealed the same optimum conditions in both types of molasses: 47 ˚C temperature, 3 bar pressure, and 9.3-9.5 pH. In the optimum condition, the recovery values of AAs for SCM and SBM were 66% and 63% for aspartic acid, 68.5% and 66% for glutamic acid, 84% and 69% for alanine, and 82% and 69% for lysine, respectively. The total efficiency values of four AAs and flux were obtained as 75% and 70 Lm-2h-2 for SCM and 67% and 45 Lm-2h-2 for SBM, respectively. The results indicated the suitability of the nanofiltration system's purifying function for AAs from SCM and SBM with desirable selectivity and purification efficiency. پرونده مقاله -
دسترسی آزاد مقاله
2 - Optimization of the ultrasound-assisted extraction process of aspartic acid from molasses and its anti-scaling capability in sugar industry evaporators
Morassa Mokhtarian M. Honarvar maryam mizani M. GhavamiThis study aimed to optimize the extraction of aspartic acid from sugar beet molasses using an ultrasound-assisted extraction method and its use as a green antiscaling agent in the evaporator tubes of the sugar industry. The results of ultrasound-assisted extraction sho چکیده کاملThis study aimed to optimize the extraction of aspartic acid from sugar beet molasses using an ultrasound-assisted extraction method and its use as a green antiscaling agent in the evaporator tubes of the sugar industry. The results of ultrasound-assisted extraction showed that the linear model is the best model to describe the behavior of aspartic acid extraction. It was determined that the optimal conditions for extracting aspartic acid using the ultrasound-assisted method include an extraction temperature of 25.09 °C, pH equal to 7, ultrasound power of 69.99%, and no ethanol. Aspartic acid extracted under optimal conditions with three different concentrations (10, 25, and 50 mg/100g) at three various temperatures (60, 90, and 120 °C) was applied to the scales of the evaporator tubes of the sugar industry. The results showed that the highest anti-scaling efficiency for all three processes was related to the treatment performed at 90 °C with a concentration of 50 mg/100 g. FESEM images showed that with increasing temperature up to 90 °C and increasing concentration up to 50 mg/100g, the scales formed on the evaporator tube changed from crystalline and uniform state to porous with fine particles. The results of EDS showed that by increasing the temperature to 90 °C and increasing the concentration to 50 mg/100g, the calcium and silica content in the scales of the evaporator tubes decreases. The results of FTIR showed that by applying aspartic acid as an antiscaling of stable crystals, the scales become smaller and more unstable crystals. پرونده مقاله -
دسترسی آزاد مقاله
3 - A glassy carbon electrode modified with boron-doped graphene oxide/ polyaspartic acid for electrochemical determination of oxazepam
Maryam Behravan Hossein Aghaie Masoud Giahi Laleh MalekniaIn this study, the electrochemical determination of oxazepam in plasma samples was studied. The composite of graphene oxide/boron (B-RGO) was synthesized via the hydrothermal method and it was cast on the glassy carbon electrode (GCE). The polyaspartic acid (poly(ASP)) چکیده کاملIn this study, the electrochemical determination of oxazepam in plasma samples was studied. The composite of graphene oxide/boron (B-RGO) was synthesized via the hydrothermal method and it was cast on the glassy carbon electrode (GCE). The polyaspartic acid (poly(ASP)) was deposited on the B-RGO by electropolymerization to prepare the modified electrode named B-RGO/ poly(ASP)|GCE. The B-RGO and B-RGO/poly ASP were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical studies were performed by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) methods. The experimental parameters affecting the reduction of oxazepam such as pH, preconcentration time, scan rate and other analysis conditions, and instrumental parameters were optimized. Under the optimal conditions, the linear range was obtained from 0.001 to 800 μM with a correlation coefficient of 0.998. The repeatability of the method for the electrode to electrode and one electrode were 4.3% and 4.9%, respectively. The limit of detection (LOD) of 0.3 nM and the limit of quantitation (LOQ) of 1 nM were obtained. The high efficiency of the developed electrode in the determination of oxazepam in the plasma sample was proved by using acceptable results and satisfactory relative recovery percentage (>90%). Based on our calculation, the heterogeneous electron transfer rate constant (ks) was 1.92 s-1. The interaction between oxazepam and modifier was single-layer and multi-layer adsorption, respectively in low and high concentrations. پرونده مقاله -
دسترسی آزاد مقاله
4 - Effect of Antioxidant D-Aspartic Acid and Thawing Rate on the Freeze-Thawing Process of Ram Semen
ح. دقیق کیا ص. وطنخواهThe study was conducted to determine the influence of D-aspartic acid (D-Asp) as antioxidant supplement and thawing rates on ram sperm motility, membrane integrity, abnormality, viability, mitochondria activity, malondialdehyde and antioxidant activities, and total anti چکیده کاملThe study was conducted to determine the influence of D-aspartic acid (D-Asp) as antioxidant supplement and thawing rates on ram sperm motility, membrane integrity, abnormality, viability, mitochondria activity, malondialdehyde and antioxidant activities, and total antioxidant capacity after freezing-thawing process. Semen samples from five mature rams (3-4 years old) were diluted with extenders (1.5% soybean lecithin, 7% glycerol) containing no supplements (control) and D-Asp (5, 10, and 15 mg/L) and cryopreserved. Frozen straws were thawed at water bath temperatures at 37 ˚C for 30s and at 60 ˚C for 6s. Addition of 10 mg/L of D-Asp improved significantly progressive motility, average path velocity, and straight-line velocity percentages after freeze-thaw (P<0.05). Plasma membrane integrity, mitochondria activity, viability, total antioxidant capacity, and glutathione peroxidase were higher in group receiving 10 mg/L in comparison to other treatments (P<0.05). Meanwhile, total abnormality significantly decreased at this concentration (10 mg/L) in comparison to the level of 15 mg/L and control group (P<0.05). Our results revealed that malondialdehyde level was lower in group receiving 10 mg/L D-Asp compared to other treatments (P<0.05). There were no significant interactions between concentrations of D-Asp and thawing protocols for any semen samples. Also, significant improvement in sperm viability and mitochondria activity were observed at 37 ˚C to 30 s thawing method (P<0.05). In overall, results of the present study demonstrate that addition of D-Asp at level of 10 mg/L have beneficial effect on quality of post-thawed ram semen cryopreserved in an extender. Therefore, this antioxidant in the suitable dose can be recommended as an additional component of ram freezing extender. The 60 ˚C to 6s thawing procedure is not an appropriate replacement for 37 ˚C to 30 s. پرونده مقاله -
دسترسی آزاد مقاله
5 - تهیه مشتقات فنیل کاربامات با آمینواسیدها و بررسی اثر آنها بر ریخت سلولهای فئوکروماسیتوما (PC12)
مهشید نیکپورنزهتی غلامحسین ریاضی صفیه ‎سادات گلستانه‎ فر فاطمه‎ سادات حسینی‎ رستمی حمید محمدحسینی ثمانه گلستانیدر این پژوهش، مشتقات جدیدی از ((2-کلرو-5-(تری‎فلوئورو‎متیل)‎فنیل)‎کاربامیک اسید) فنیل استر با آمینواسیدهای سیستئین، تریپتوفان، آسپارتیک اسید، ایزولوسین که منتخب چهار گروه اصلی آمینواسیدهای آلیفاتیک غیرقطبی، آروماتیک غیرقطبی، قطبی بدون بار و قطبی با بار م چکیده کاملدر این پژوهش، مشتقات جدیدی از ((2-کلرو-5-(تری‎فلوئورو‎متیل)‎فنیل)‎کاربامیک اسید) فنیل استر با آمینواسیدهای سیستئین، تریپتوفان، آسپارتیک اسید، ایزولوسین که منتخب چهار گروه اصلی آمینواسیدهای آلیفاتیک غیرقطبی، آروماتیک غیرقطبی، قطبی بدون بار و قطبی با بار منفی هستند و متیل استر به دست آمده از آن‎ها تهیه و با روش های طیفسنجی فروسرخ تبدیل فوریه (FTIR) و طیف سنجی رزونانس مغناطیس هسته ای (1H NMR) شناسایی و مورد تأیید قرار گرفتند. تاثیر ترکیب‎های خالص ((2-کلرو-3-(تری‎فلوئورومتیل)‎فنیل)‎کاربامیک اسید فنیل استر، ((2-کلرو-5-(تری‎فلوئورومتیل)فنیل)کارباموئیل)-D-تریپتوفان و 1-(2-کلرو-5-(تری‎فلوئورومتیل)فنیل)-2و6-دی‎اکسوهگزاهیدروپیریمیدین‎-4-کربوکسیلیک اسید بر ریخت سلول‎های فئوکروموسیتوما (PC12) به کمک عکس‎برداری میکروسکوپی موردبررسی قرارگرفت. غلظت کشنده محاسبه‎شده برابر 10 میکرومولار و زمان موردسنجش 48 ساعت تعیین شد. بررسی تصاویر میکروسکوپ معکوس حاکی از اثر کشندگی قابل‎قبول فراورده های تهیه‎شده بود. پرونده مقاله
سکوی نشر دانش
سند یا سکوی نشر دانش ،سامانه ای جهت مدیریت حوزه علمی و پژوهشی نشریات دانشگاه آزاد می باشد
پیوندهای سایت
مراکز مرتبط
پشتیبانی
صفحات رسمی
حقوق این وبسایت متعلق به سامانه مدیریت نشریات دانشگاه آزاد اسلامی است.
حق نشر © 1403-1400