A new blend of polymeric encapsulation of azithromycin by spray-drying with a pH responsive in drug release

The microencapsulation of macrolides with polymers has been reported to retard the release of the drug in oral cavity. However, these methods are unable to control drug release in gastrointestinal tract. The aim of the present study was to investigate the effect of formulation of a new polymeric encapsulation of azithromycin which is suitable for both masking and sustained release usage. Eudragit E100 and polyethylene glycol (PEG) 4000 were chosen as the barrier coatings. The spray drying technique was used to obtain the microcapsules containing azithromycin. To obtain the initial results, the effects of several parameters were evaluated. A 3:2:1 ratio of E100:PEG 4000:azithromycin at pH 6 gave the best coating condition. Thermogravimetric analysis and IR analysis data confirmed the encapsulation of azithromycin inside polymers. The encapsulated drug was released in different rates from the particles by changing the pH (1.7 and 7.4). An analysis of the kinetic release properties indicates that the release of the drug is a combination of swelling and diffusion mechanism. The synergistic cooperation between polymers and drug due to the existence of several hydrogen bonding is supposed to influence the pH-responsive property of the encapsulated drug. Moreover, the use of mixtures of E100 and PEG 4000 appears to offer a good balance between cost and efficiency.     

One-step synthesized azo-dye modified Mg-Al LDH reinforced biobased semi-aromatic polyamide containing naphthalene ring; study on thermal stability and optical properties

A new series of polyamide Mg-Al layered double hydroxide (LDH) nanocomposites (PANC) were prepared using solution intercalation method. The biobased polyamide (PA) was synthesized using direct polycondensation reaction. Organo azo-dye modified Mg-Al LDH (OLDH) was prepared by one-step method and its effect on the thermal and optical properties of PA was investigated. The X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) results showed the uniform distribution of LDH sheets in the PA matrix. The UV-Vis spectra of PANC showed a blue shift as well as reduction in absorbance intensities and the photoluminescence studies revealed the higher emission intensities for PANC as compared to the neat PA. The results of thermogravimetric analysis (TGA) in both nitrogen and air atmospheres showed that the addition of OLDH up to 5 mass% was slightly improved thermal properties of PA.     

Roll bonding of AA5052 and polypropylene sheets: Bonding mechanisms,microstructure and mechanical properties

Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was also observed that an increase in the rolling temperature increases bonding strength because the polymer penetrates the AA5052 surface irregularities more easily, the PP-g-MAH molecules move more smoothly toward the AA5052 surface, and finally there are more chemical interactions among the layers. An Increase in the bonding strength through increasing the AA5052 surface roughness was attributed to an increase of the van der Waals force and more interaction surface among the layers along with higher mechanical interlocking in the shear tension test.     

Optimizing the location of the gas injection well during gas assisted gravity drainage in a fractured carbonate reservoir using artificial intelligence

Gas assisted gravity drainage (GAGD) is a novel subdivision of gas injection method. In this method the injection wells are located in the upper bed of the oil zone, and the production wells are drilled at the bottom bed of the oil zone. Reservoir simulation is among the decision tools for investigating production rate and selecting the best scenarios for developing the oil and gas fields. Selecting the location of the injection wells for reaching the optimized pressure and production rate is one of the most significant challenges during the injection process. Recent experiences have shown that artificial intelligence (AI) is a reliable solution for taking the mentioned decision appropriately and in a least possible time. This study is attributed to the investigation of applying the artificial neural network (ANN) as an artificial intelligence method and a potent predictor for choosing the most proper location for injection in a GAGD process in a fractured carbonate reservoir. The results of this investigation clearly show the efficiency of the ANN as a powerful tool for optimizing the location of the injection wells in a GAGD process. The comparison between the results of ANN and black oil simulator indicated that the predictions obtained from the ANN is highly reliable. In fact the production flow rate and pressure can be obtained in every possible location of the injection well.     

Genetic Polymorphisms in the APOA1 Gene and their Relationship with Serum HDL Cholesterol Levels

Low high density lipoprotein cholesterol (HDL-C) is a known risk factor of coronary artery disease. Apolipoprotein A1 (APOA1) is the most abundant component of HDL-C. This study aimed at identifying sequence variations (rare and common) in the APOA1 gene and its association with serum HDL-C levels. This study was conducted from April 2012 to February 2013 on 79 Tehranians (participants of Tehran Lipid and Glucose Study) with extremely low HDL-C (within the 5th percentile) and 63 individuals with extremely high HDL-C (within the 95th percentile) levels. After DNA amplification by PCR, DNA sequencing of all three exons and 700 bps of promoter region of the APOA1 gene was performed. Sequence results were analyzed and interpreted using the appropriate software and variants were identified. After sequencing 42 common and rare variants were identified, 11 of which were known variants and the others had been unreported so far. Of the exonic variants, 11 were missense, 6 were synonymous and 1 was nonsense. There was a significant association between serum HDL-C and variant of rs2070665 as well as variants Chr.11:116707788, Chr.11:116708059, Chr.11:116708036, Chr.11:116707729, rs201148448, Chr.11:116707018, Chr.11:116707801, Chr.11:116708530, Chr.11:116708088, rs121912724 and Chr.11:116706966 (p < 0.001). Variants Chr.11:116707018, rs121912724 and 2070665 were independent predictors of the HDL-C level (p < 0.001). SNP Chr.11:116707018 was the strongest predictor of the HDL-C level (OR 7.527, p < 0.001). This study identified 42 variants in APOA1 gene, 31 of which were new variants. Three variants of rs2070665, rs121912724 and Chr.11:116707018 could predict the HDL-C level independently. Variant rs2070665 was protective against low-HDL-C levels while variants rs121912724 and Chr.11:116707018 were risk factors for that in our population.     

Mangrove Oyster (Crassostrea belcheri) as a Biomonitor Species for Bioavailability of Polycyclic Aromatic Hydrocarbons (PAHs) from Sediment of the West Coast of Peninsular Malaysia

ABSTRACT

Rapid industrialization and urbanization in the west coast of Peninsular Malaysia has caused increasing pollution particularly of petroleum and petroleum by-products. Surface sediment and mangrove oyster (Crassostrea belcheri) were collected from five mangrove ecosystems in the west coast of Peninsular Malaysia and investigated for bioavailability of polycyclic aromatic hydrocarbons (PAHs). Sampling locations were selected from both remote areas with few or no previous records of petroleum pollution such as Pulau Merambong and polluted areas that are under international attention such as Klang mangrove ecosystem. PAH fractions were obtained through soxhlet extraction and two-step column chromatography and the fractions were injected to gas chromatography-mass spectrometry (GC-MS) for analysis. The concentrations of PAHs ranged from 151 to 4973 ng g^?1 dw in the sediments, while from 309 to 2225 ng g^?1 dw in the oysters. When tested for diagnostic ratios, a predominance of pyrogenic source PAHs was detected in the sediments, whereas PAHs in the oysters had mixed petrogenic and pyrogenic sources. A significant correlation (p < 0.05) was found between high molecular weight (HMW) PAHs in the sediments and oysters and biota accumulation factors (BAFs) of PAHs were approaching or exceeding unity indicating the ability of mangrove oyster in bioaccumulation of PAHs. Overall, this study indicates that mangrove oyster (C. belcheri) can be used as a biomonitor species for PAHs in an aquatic environment.     

Effect of Different Substrate Pre-Treatments on the Resistance of Aluminum Joints to Moist Environments

The goal of this work was to evaluate and compare the performance of different surface pre-treatments applied to aluminium single lap joints exposed to warm moisture. Four different processes were considered: 1) degreasing-roughening; 2) degreasing-roughening and phosphoric acid anodising; 3) degreasing-roughening and conditioning with Picklex®20 (a water-based product for metal surface preparation); 4) degreasing-roughening and phosphoric acid anodising and contaminating the adherend surface with CaCl₂ to accelerate the tests.

After each pre-treatment, lap-shear specimens were prepared with the open face technique. The half-joints were exposed to warm moisture (50°C, 100% RH) for times up to 4 weeks, then they were completed and subjected to mechanical testing.

The results show that anodising yields the best durability, as strength remained practically constant over time; all the other groups of specimens exhibited progressive reduction in strength and wider scatter of the results. A large role is played by interfacial damage of the adherends, since, under increasing exposure time, failure tends to occur as separation at the adhesive-metal interface. The strength decreased dramatically also for the anodised specimens when the surface was contaminated, which evidences the role of the interfacial damage. The interpretation is supported also by scanning electronic microscopy observation and energy-dispersive X-ray analysis.     

MODELING OF MEMBRANE FOULING AND FLUX DECLINE IN MICROFILTRATION OF OILY WASTEWATER USING CERAMIC MEMBRANES

One of the major problems in pressure-driven membrane processes is reduction of flux far below the theoretical capacity of the membrane. The results of an experimental study of fouling mechanisms of ceramic membranes in separation of oil from synthesized oily wastewaters are presented. Mullite microfiltration (MF) membranes were synthesized from kaolin clay as MF ceramic membranes. The rejection of total organic carbon (TOC) for the synthetic feeds was found to be more than 94% by these membranes. Hermia's models were used to investigate the fouling mechanisms of membranes. The effect of pressure, cross flow velocity (CFV), temperature, oil concentration, and salt concentration on flux decline were investigated. The results showed that the cake filtration model can well predict the flux decline of mullite ceramic membranes; average error of this model is less than 7%. The results show that by increasing pressure from 0.5 to 4 bar, porosity of the cake layer on the mullite membranes decreases from 25.68% to 14.98%. After the cake filtration model, the intermediate pore blocking model was found to well predict the experimental data with an average error less than 10.5%.