Release of human growth hormone from an in-situ implant modulated by poly(ethylene glycol) dimethyl ether and tris(hydroxymethyl) aminomethane

A patient-friendly delivery system to release human growth hormone (hGH) is very desirable. In situ forming implant systems (ISIs) can provide a long acting and effective protein delivery. In these systems, solvents and additives play major roles in drug release. In this study, four groups of PLGA-based ISIs containing hGH were prepared in N-methyl-2-pyrrolidone (NMP) and poly(ethylene glycol) dimethyl ether (PEG-DME) as solvents with and without tris(hydroxymethyl) aminomethane (Tris) as stabilizer. Several analyses were used to investigate the implants, which include release profile, viscosity, contact angle, gel permeation chromatography (GPC), scanning electron microscopy (SEM), hGH and IGF-1 serum measurements and histopathology. In in vitro release experiments, the hGH cumulative release from PEG-DME system was twice that from NMP system during 14 days, and hGH release was tripled in the presence of Tris. With the addition of Tris to the ISIs containing PEG-DME, the water penetration, interconnectivity of pores and inner channels, surface pores and hydrophilicity were increased. Moreover, the effect of Tris on the hGH stabilization synergized its positive effects and increased the hGH final cumulative release. Results of the ISIs containing PEG-DME and Tris injection in rabbits demonstrated a reduced tissue inflammation. Moreover, the 14-days serum levels of the hGH and IGF-1 of this system in recipient rabbits were comparable to those of the commercial daily injection samples.

     

Synthesis and evaluation of NiO@MCM-41 core–shell nanocomposite in the CO<Subscript>2</Subscript> reforming of methane

In this paper, the synthesis of core shell structured NiO@MCM-41 nanocomposite via vesicles as soft template is reported for the first time. Its catalytic performance was investigated in the CO₂ reforming of methane (CRM) conversion. Stable vesicles first formed with CTAB/SDBS surfactant ratio of 1:2. Nickle nitrate was added to the vesicle mixture followed by addition of the aqueous solution of vesicle containing Ni cations inside to the MCM-41 gel. After high-temperature calcination, NiO@MCM-41 nanocomposite were obtained. The structural symmetry and the surface morphology were characterized by transmission electron microscope (TEM), low angle X-Ray Diffraction (XRD) and N₂ adsorption/desorption analysis. TEM image confirmed core–shell structure and the hexagonally ordered structure of shell of MCM-41 silica. The results indicated that the average diameter of synthesized core–shell NiO@MCM-41 particles is 70–80 nm and the most of them are of spherical shape. The result of small angle XRD and N₂ isotherm adsorption/desorption analyses indicated successfull formation of mesoporous shell. Hydrogen consumption by the catalyst mainly at 700 °C in TPR profile showed the strong interaction of the most of Nickel content with the support. CRM conversion on the prepared catalyst after 245 min of reaction led to H₂ conversion at 42%, CO₂ conversion at 48% with H₂/CO yield ratio of 0.8.     

Online Characterization of Syngas Particulates Using Aerosol Mass Spectrometry in Entrained-Flow Biomass Gasification

Entrained flow gasification is a promising technique where biomass is converted to a synthesis gas (syngas) under fuel-rich conditions. In contrast to combustion, where the fuel is converted to heat, CO₂, and H₂O, the syngas from gasification is rich in energetic gases such as CO and H₂. These compounds (CO and H₂) represent the building blocks for further catalytic synthesis to chemicals or biofuels. Impurities in the syngas, such as particulates, need to be reduced to different levels depending on the syngas application. The objective of this work was to evaluate the amount of particulates; the particle size distribution and the particle composition from entrained flow gasification of pine stem wood at different operating conditions of the gasifier. For this purpose, online time resolved measurements were performed with a soot particle aerosol mass spectrometer (SP-AMS) and a scanning mobility particle sizer (SMPS). The main advantage of SP-AMS compared to other techniques is that the particle composition (soot, PAH, organics, and ash forming elements) can be obtained with high time resolution and thus studied as a direct effect of the gasifier-operating conditions. The results suggest that syngas particulates were essentially composed of soot at these tested process temperatures in the reactor (1200–1400°C). Furthermore, the AMS analysis showed a clear correlation between the amounts of polycyclic aromatic hydrocarbons (PAH) and soot in the raw syngas. Minimization of soot and PAH yields from entrained flow gasification of wood proved to be possible by further increasing the O₂ addition.

Copyright 2014 American Association for Aerosol Research     

Nanoscale Optoregulation of Neural Stem Cell Differentiation by Intracellular Alteration of Redox Balance

Regulation of stem cell (SC) fate, a decision between self‐renewal and differentiation, is of immense importance in regenerative medicine and has been proven to be a powerful stimulus regulating many cell functions influencing the SC fate. This study uses triphenylphosphonium‐functionalized gold nanoparticles (TPP‐AuNPs) to explore the interplay of intracellular electromagnetic (EM) exposure and the SC fate. Localized EM waves are generated inside neural stem cells (NSCs) to stimulate TPP‐AuNPs (AuNPs), targeting the mitochondria through inducing reactive oxygen species and differentiating these cells into neurons. Following laser irradiation of TPP‐AuNPs‐transfected NSCs, their differentiation to neurons is monitored by tracing the relevant markers both at the genetic and protein levels. The electrophysiology technique is further used to examine the functionality of neurons. The results confirm that TPP‐AuNPs subjected to electromotive forces have the potential to regulate cellular fate, although further investigations are still required to shed light on the mechanisms underlying the interaction of EM‐stimulated TPP‐AuNPs on cellular fate to design highly adjustable cell differentiation and reprogramming methods.     

Laboratory and Field Test of a Sampling Method for Characterization of Combustion Aerosols at High Temperatures

The objective of this study was to design and experimentally examine a sampling method for high-temperature aerosols from biomass combustion, in which nucleation and condensation from fly ash forming vapors is controlled. The sampling method includes a high-temperature probe in which the hot gas is diluted and then cooled. Laboratory results from sampling a model aerosol with known concentrations of SiO₂ particles and KCl vapor showed that when using a high dilution ratio, the KCl vapor was effectively separated from the aerosol by deposition onto the probe walls. When a lower dilution ratio was used, the KCl vapor generated a distinct nucleation mode when cooled in the probe. The sampling method was also used for sampling flue gas from a circulating fluidized bed boiler fired with forest residues. The results suggest that the major fractions of Ca, K, S, and Zn were present as particles at 780°C, whereas most of the Cl and Pb were present as gases. The field results are consistent with results previously reported and indicate that the method can be used for efficient and precise characterization of high-temperature combustion aerosols containing inorganic vapors.     

Analysis of Near Well-bore Behavior of Gas Condensate Reservoir in Production Stage

Abstract

The formation of condensate banking in the near well-bore region will lead to the reduction in gas relative permeability and loss of well deliverability. This loss is investigated by conducting a series of fine grid numerical compositional simulation with the gas condensate and dry gas reservoir data. Also, a method for calculation of condensate blockage skin factor is introduced in which the skin factor is calculated using dry gas and gas condensate simulation production data. The authors also found that absolute permeability and pressure drawdown of the producing well have significant influence on the well gas deliverability and condensate blockage skin factor.     

An Electrochemical Nanosensor for Simultaneous Voltammetric Determination of Ascorbic Acid and Sudan I in Food Samples

In this work, we describe application of a high-sensitive electrochemical sensor for determination of ascorbic acid (AA) in the presence of high concentration of Sudan I in food samples. In the first step, we study synthesis and characterization of NiO/NPs with X-ray diffraction (XRD) method. In the second step, application of NiO/NPs describe in the preparation of carbon-paste electrode modified with (9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-4-ethylbenzene-1,2-diol (DEDED) as a high-sensitive and selective voltammetric sensor for determination of AA and Sudan I. The electrocatalytic oxidation of AA at the modified electrode was investigated by cyclic voltammetry, chronoamperometry and square wave voltammetry (SWV). For the mixture containing AA and Sudan I, the peaks potential was well separated from each other. Their square wave voltammetrics peaks current increased linearly with their concentration at the ranges of 0.01–600 and 0.5–1,000 μM, with the detection limits of 0.006 and 0.2 μM, respectively. Finally, the proposed method was also examined as a selective, simple, and precise electrochemical sensor for the determination of AA and Sudan I in real samples such as fruit juices, fresh vegetable juice, chilli sauce and tomato sauce.     

Application of Seismic Attribute Technique to estimate the 3D model of Hydraulic Flow Units: A case study of a gas field in Iran

One of the most important steps in evaluation and development of hydrocarbon reservoirs is the mapping of their characteristics. Nowadays, Seismic Attribute Technique is used to build parameters of hydrocarbon reservoirs in inter-well spaces. One of these parameters is the Flow Zone Index (FZI) that has a significant effect on different stages of evaluation, completion, primary and secondary production, reservoir modeling and reservoir management. The aim of this study is to introduce an equation using seismic attribute and FZI log in wells and then generalize it to predict FZI throughout the reservoir. For this purpose, acoustic impedance (AI) volume as an external attribute was created while internal attributes were computed from seismic data. After that, The best set of attributes was determined using stepwise regression after which seismic attributes were applied to multi-attribute analysis to predict FZI. Then, the attribute map resulted from multi-attribute analysis was used to interpret the spatial distribution of the gas bearing carbonate layers. Finally, the optimum number of Hydraulic Flow Units (HFU) was determined by analyzing the break point in the plot of cumulative frequency of FZI for wells and was generalized all over the reservoir by using the 3D HFU model. The results demonstrated that multi-attribute analysis was a striking technique for HFU estimation in hydrocarbon reservoirs that reduces cost and increases rate of success in hydrocarbon exploration. Distribution of producible hydrocarbon zones along with the seismic lines around the reservoir was characterized by studying this model which can help us in choosing the location of new wells and more economical drilling operations.     

Effect of fly ash and H2S on a Ni-based catalyst for the upgrading of a biomass-generated gas

The main concern about the technology for the production of hydrogen and transport fuels by biomass gasification is the presence of contaminants (H₂S, tars, fly ash, alkali, and heavy metals, ammonia) that are poisonous for the catalysts used for upgrading the biomass-generated gas. The impact of the main contaminants on a Ni/MgAl(O) reforming catalyst was studied in a laboratory environment, by exposing the studied sample to H₂S, NH₃, K₂SO₄, KCl, ZnCl₂, and a solution derived from biomass fly ash. Lastly, the catalyst was also streamed with a gas produced by a bench-scale downdraft gasifier. The extent of deactivation was examined in the methane steam reforming reaction, under different operational conditions. The main effect of the treatments was a decrease in the bulk surface area and in the metal dispersion. Streaming H₂S quickly deactivated the catalyst; however, the activity was recovered by increasing the inlet temperature or by adding O₂ to the stream. In further laboratory tests, the performances of the catalyst seemed not to be greatly affected by either the above treatments or by the presence of ammonia in the fed water. The catalyst produced a syngas composition close to that predicted at equilibrium even after being streamed with the biomass-generated gas.