Effect of poly‐glutamate on uptake efficiency and cytotoxicity of cell penetrating peptides

Cell penetrating peptides (CPPs) were developed as vehicles for efficient delivery of various molecules. An ideal CPP‐peptide should not display any toxicity against cancer cells as well as healthy cells and efficiently enter into the cell. Because of the cationic nature and the intrinsic vector capabilities, these peptides can cause cytotoxicity. One of the possible reasons for toxicity of CPPs is direct translocation and consequently, pore formation on the plasma membrane. In this study it was demonstrated that interaction of poly‐glutamate with CPP considerably reduced their cytotoxicity in A549 cell. This strategy could be useful for efficient drug delivery mediated by CPP.Inspec keywords: cellular biophysics, polymers, drug delivery systems, biomedical materials, toxicology, molecular biophysicsOther keywords: drug delivery, A549 cell, plasma membrane, pore formation, cancer cells, poly‐glutamate, cytotoxicity, uptake efficiency, cell penetrating peptides     

A mesh-free method using exponential basis functions for laminates modeled by CLPT,FSDT and TSDT – Part I: Formulation

In this part of the paper, we introduce a meshfree approach for static analysis of isotropic/orthotropic cross-ply laminated plates with symmetric/non-symmetric layers. In this method, the solution is first split into homogenous and particular parts and then the homogenous part is approximated by the summation of an appropriately selected set of exponential basis functions (EBFs) that are restricted to satisfy the governing partial differential equation (PDE). The particular solution is derived using a similar approach and another series of EBFs. The imposition of the boundary conditions is performed by a collocation method through a discrete transformation technique. The solution method allows us to obtain semi-analytical solution of plate problems with various shapes and boundary conditions. Although implemented for cross-ply laminates in this work, the proposed method is applicable to more general lamination cases as long as the governing PDEs are of constant coefficient type. This part of the paper is devoted to the basic features of the formulation and the evaluation of the EBFs using classical, first and third order shear deformation theories. Explicit expressions are given for special cases for further use.     

The Effect of Weight Material Type on Barite Sag Tendency

Settling of weight materials is a phenomenon that occurs in high-pressure formations where a high mud weight is needed. Barite sag is roughly defined as the change in density due the settling of weight materials that observed when circulating bottoms up following operations such as tripping pipe where the mud has not been circulating for an extended period of time. This may lead to problems such as lost circulation, well control difficulties, poor cement jobs, and stuck pipe in oil industry. In deviated wells, the settling distance to the lower side of the wall is small in comparison to vertical wells. This leads to rapid generation of solids beds and consequently, sag problems are particularly severe in deviated wells. The authors present the settling rate of different weight materials in muds with mathematical method. Furthermore, it investigates the effect of weight material type and hindered settling factor on settling rate. Moreover, the type of weight materials for barite sag management is recommended.     

Stable Inverted Polymer/Fullerene Solar Cells Using a Cationic Polythiophene Modified PEDOT:PSS Cathodic Interface

A cationic and water‐soluble polythiophene [poly[3‐(6‐pyridiniumylhexyl)thiophene bromide] (P3PHT⁺Br^?)] is synthesized and used in combination with anionic poly(3,4‐ethylenedioxythiophene):poly(p‐styrenesulfonate) (PEDOT:PSS)^? to produce hybrid coatings on indium tin oxide (ITO). Two coating strategies are established: i) electrostatic layer‐by‐layer assembly with colloidal suspensions of (PEDOT:PSS)^?, and ii) modification of an electrochemically prepared (PEDOT:PSS)^? film on ITO. The coatings are found to modify the work function of ITO such that it could act as a cathode in inverted 2,5‐diyl‐poly(3‐hexylthiophene) (P3HT)/[6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM) polymer photovoltaic cells. The interfacial modifier created from the layer‐by‐layer assembly route is used to produce efficient inverted organic photovoltaic devices (power conversion efficiency ～2%) with significant long‐term stability in excess of 500 h.     

ANALYSIS OF A GEODESIC DOME SOLAR FRUIT DRYER

This paper analyzes use of geodesic domes as low cost and practical solar energy drying systems, especially for developing countries. A geodesic dome solar fruit dryer was designed, constructed and tested for drying grapes. The structure was constructed using wooden members, covered with transparent tedlar plastic and a black absorber inner shell. Fresh air is heated in the space between the outer shell and the absorber sheet. The hot air then passes through the fruits on the trays and exits from the top. The dryer was tested for drying grapes under two different modes, namely natural convection and forced air flow. In addition, theoretical results were obtained by thermal-electrical simulation and considering the heat and mass transfer phenomena between the air and the grapes.     

The Best Common Ways to Manage Barite Sag in HPHT and Deviated Operations With a Case Study in the Iran Oil Industry

Abstract

Barite sag is an oilfield term used to describe significant density variations while circulating bottoms up after a trip, logging run, or other operation that requires the mud to remain static for an extended period of time. Sag is caused by static or dynamic settling followed by slumping of the weighted material. Static sag, as the name suggests, is caused when circulating is stopped for an extended period of time, and the weighting agents begin to settle under the influence of gravity. Due to slumping, dynamic sag occurs frequently in inclined holes. However, the problem has been exacerbated by the increased frequently of high-angle wells with the associated increase in particle settling rate, which occurs in an inclined fluid column. The settling of solids is enhanced by convective currents created by density differences in the fluid across the annulus cross-section. This effect is frequently referred to as the Boycott effect. The authors present the most effective ways to avoid the occurrence of barite sag in high-pressure high-temperature drilling operations, and in high-angle wells beside a case study in Gachsaran formation in the Ahwaz oil field of Iran. The methods include replacing barite with other weighted materials such as ilmenite or manganese tetraoxide. The lower the Equivalent Circulating Density, the higher the rate of drilling operation as well as the lower pressure losses especially in mud pumps. The authors introduce a new water-based mud formulation that uses attapulgite and xanthan gum as viscosifiers. By using a Brookfield viscometer (DV-II + Pro), viscosities of different muds at ultralow shear rates were measured. According to their rheological properties, a desirable mud formulation was developed.     

Bio-oil production and upgrading research: A review

Biomass can be utilized to produce bio-oil, a promising alternative energy source for the limited crude oil. There are mainly two processes involved in the conversion of biomass to bio-oil: flash pyrolysis and hydrothermal liquefaction. The cost of bio-oil production from biomass is relatively high based on current technologies, and the main challenges are the low yield and poor bio-oil quality. Considerable research efforts have been made to improve the bio-oil production from biomass. Scientific and technical developments towards improving bio-oil yield and quality to date are reviewed, with an emphasis on bio-oil upgrading research. Furthermore, the article covers some major issues that associated with bio-oil from biomass, which includes bio-oil basics (e.g., characteristics, chemistry), application, environmental and economic assessment. It also points out barriers to achieving improvements in the future.     

The effect of different solvents on the density of undersaturated athabasca bitumen: Application in VAPEX and ES-SAGD

Predicting the density of bitumen after solvent injection is highly required in solvent-based recovery techniques like expanding solvent-steam assisted gravity drainage (ES-SAGD) and vapor extraction (VAPEX) in order to estimate the cumulative oil recovery by these processes. Using experimental procedures for this purpose is so expensive and time-consuming; therefore, it is crucial to propose a rapid and accurate model for predicting the effect of various solvents on the dilution of bitumen. In this study, an adaptive neuro-fuzzy interference system is introduced to estimate the effect of methane, ethane, propane, butane, carbon dioxide, and n-hexane on the density of undersaturated Athabasca bitumen in wide ranges of operating conditions. The obtained results were in an excellent agreement with experimental data with coefficients of determination (R²) of 0.99997 and 0.99948 for training and testing datasets, respectively. Statistical analyses illustrate the superiority of the proposed model in predicting the bitumen density at different conditions.