Bond Performance of Carbon Fiber-Reinforced Polymer Bar with Dual Functions of Reinforcement and Cathodic Protection for Reinforced Concrete StructuresRead the full article
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Perspectives, Tendencies, and Guidelines in Affinity-Based Strategies for the Recovery and Purification of PEGylated Proteins
In recent years, the effective purification of PEGylated therapeutic proteins from reaction media has received particular attention. Although several techniques have been used, affinity-based strategies have been scarcely explored despite the fact that, after PEGylation, marked changes in the molecular affinity parameters of the modified molecules are observed. With this in mind, future contributions in the bioseparation of these polymer-protein conjugates are expected to exploit affinity in chromatographic and nonchromatographic techniques which will surely derive in the integration of different operations. However, this will only occur as novel ligands which are simultaneously found. As it will be mentioned, these novel ligands may be screened or designed. In both cases, computer-aided tools will support their identification or development. Additionally, ligand discovery by high-throughput screening (HTS) is believed to become a fast, economic, and informative technology that will aid in the mass production of ligands along with genetic engineering and related technologies. Therefore, besides analyzing the state of the art in affinity separation strategies for PEGylated molecules, this review proposes a basic guideline for the selection of adequate ligands to provide information and prospective on the future of affinity operations in solving this particular bioengineering problem.
Elliptical FRP-Concrete-Steel Double-Skin Tubular Columns under Monotonic Axial Compression
Hybrid FRP-concrete-steel double-skin tubular columns (hybrid DSTCs) are a novel form of hollow columns consisting of an outer FRP tube, an inner steel tube, and an annular layer of concrete between the two tubes. Due to the effective confinement of the two tubes, the concrete in hybrid DSTCs is well confined, leading to excellent ductility and strength enhancement. Hybrid DSTCs also have excellent corrosion resistence due to the effective protection of the outer FRP tube. However, existing studies mainly focused on hybrid DSTCs with a circular cross-section. When subjecting to different loads in the two horizontal directions, elliptical columns are preferred as they can provide different bending stiffness and moment capacity around two axes of symmetry without significantly reducing the confining effect of the FRP tube. This paper extends the existing work on circular DSTCs to elliptical DSTCs with a particular focus on four issues: the effect of elliptical aspect ratio (i.e., the ratio of the major axis to the minor axis of the outer elliptical cross-section), the effect of the FRP tube thickness, the effect of void area ratio (i.e., the ratio of the area of concrete void to the area of the outer elliptical section), and the effect of the cross-section of the inner steel tube (i.e., both rectangular and elliptical steel tubes were used). Experimental results show that, the averaged peak stress of the confined concrete in elliptical DSTCs increases with the increase in the elliptical aspect ratio, whereas the elliptical aspect ratio has no obvious effect on the ultimate axial strain; the cross-section shape of the inner steel tube has significant effect on the axial stress-strain behavior of the confined concrete in elliptical DSTCs; elliptical DSTCs with an elliptical steel tube exhibit much better ductility and strength enhancement than those specimens with a rectangular steel tube. A simple stress-strain model of confined concrete was proposed for elliptical DSTCs to account for the effects of the elliptical aspect ratio, the inner void, and the shape of the inner steel tube, which can provide reasonably accurate but conservative predictions.
Development Performance and Pressure Field Evolution of ASP Flooding
ASP (alkali-surfactant-polymer) is acknowledged as an effective technology to improve the oil recovery. The microscopic displacement efficiency and macroscopic sweep efficiency have been discussed in detail for the past few years. However, development performance, especially pressure characteristics, needs to be further studied. This paper aims to explore the pressure evolution performance during ASP flooding, of which the results will shed light on development characteristics of ASP flooding. The study on ASP flooding pressure field development is conducted by laboratory and numerical methodology. A large sandpack laboratory model with vertical heterogeneous layers is used to monitor pressure performance during the ASP flooding. With the help of interpolation methods, a precise and intuitive pressure field is obtained based on pressure data acquired by limited measurement points. Results show that the average formation pressure and its location are changing all the time in the whole process. In addition, the influence of heterogeneity and viscosity on recovery and pressure is also probed in this paper. We built a numerical simulation model to match the experiment data considering the physical and chemical alternation in ASP flooding. Also, response surface methodology (RSM) is adopted to obtain the formula between pressure functions and influencing factors.
Fabrication & Characterization of Chitosan Coated Biologically Synthesized TiO2 Nanoparticles against PDR E. coli of Veterinary Origin
Treatment of pandrug resistant (PDR) Escherichia coli strain is the leading causative agent of bovine mastitis worldwide. Hence, becoming a potential threat to veterinary and public health. Therefore, to control the infection new nontoxic, biocompatible antimicrobial formulation with enhanced antibacterial activity is massively required. Current study was planned to synthesize chitosan coated titanium dioxide nanoparticles (CS-NPs coated TiO2). Coating was being done by chitosan nanoparticles (CS-NPs) using ionic gelation method. Aqueous solution of Moringa concanensis leaf extract was used to synthesize titanium dioxide nanoparticles (TiO2 NPs). The synthesized nanoformulations were characterized by using XRD, SEM, and FTIR. X-ray diffraction (XRD) analysis indicated the crystalline phase of TiO2 NPs and CS-NPs coated TiO2 NPs. Scanning Electron Microscopy (SEM) confirmed spherical shaped nanoparticles size of chitosan NPs ranging from 19–25 nm and TiO2 NPs 35–50 nm. Thesize of CS-NPs coated TiO2 NPs was in the range of 65–75 nm. The UV-Vis Spectra and band gap values illustrated the red shift in CS-NPs coated TiO2 NPs. Fourier transform infrared (FTIR) spectroscopy confirmed the linkages between TiO2 NPs and chitosan biopolymer, Zeta potential confirmed the stability of CS-NPs coated TiO2 NPs by showing 95 mV peak value. In-vitro antibacterial activity of CS-NPs coated TiO2 NPs and Uncoated TiO2 NPs was evaluated by disc diffusion method against PDR strain of E. coli isolated from mastitic milk samples. The antibacterial activity of all the synthesized nanoformulations were noted and highest antibacterial activity was shown by CS-NPs coated TiO2-NPs against pandrug resistant (PDR) E. coli strain with the prominent zone of inhibition of 23 mm. Morphological changes of E. coli cells after the treatment with MIC concentration (0.78 μg/ml) of CS-NPs coated TiO2 NPs were studied by transmission electron microscopy TEM showedrigorous morphological defectand has distorted the general appearance of the E. coli cells. Cytotoxicity (HepG2 cell line) and hemolytic (human blood) studies confirmed nontoxic/biocompatible nature of CS-NPs coated biologically synthesized TiO2 NPs. The results suggested that biologically synthesized and surface modified TiO2 NPs by mucoadhesive polysaccharides (e.g. chitosan) coating would be an effective and non-toxic alternative therapeutic agent to be used in livestock industry to control drug resistant veterinary pathogens.
Experimental Study of Moisture Content Effect on Geotechnical Properties of Solidified Municipal Sludge
Moisture content is an important factor affecting the geotechnical properties of solidified municipal sludge (MMS). Typical municipal sludge in China was chosen to investigate the effects of initial moisture content (defined as ) on geotechnical properties of MMS solidified by self-developed CERSM solidifying agent. In addition, the microstructure changes of solidified sludge samples in this study were explored with scanning electron microscopy and mercury intrusion porosimetry. Mechanical experiment results showed that the unconfined compressive strength, cohesion, and internal friction angle of the MMS increased with the decrease in initial moisture content, but the permeability coefficient changed oppositely. The permeability coefficient of solidified sludge samples was between 10−8 and 10−10 cm/s. But after the drying-saturated process, the permeability coefficient of MMS can be increased up to 4 times, mainly due to the formation of a considerable number of microconnected pores and microcracks in the process of drying. The research results are of great significance to the safe disposal and utilization of municipal sewage sludge in China.
In Situ Synthesis and Characterization of ZnO/Chitosan Nanocomposite as an Adsorbent for Removal of Congo Red from Aqueous Solution
ZnO/chitosan nanocomposite was successfully synthesized by in-situ precipitation method. The material was characterized by XRD, FESEM, TEM, FTIR, BET, and TGA. Results show that ZnO/chitosan nanocomposite has spherical shape with the average size of 20–25 nm. BET surface area and the average pore size of ZnO/chitosan nanocomposite are 2.2436 (m2/g) and 12.2 nm, respectively. The material was applied as an adsorbent for congo red removal from aqueous solutions. The congo red adsorption is better described by the Langmuir model () than by the Freundlich model (). Therefore, it can be presumed that congo red was adsorbed in a single monolayer with the theoretical maximum adsorption capacity of 227.3 (mg/g). This is comparable to other available adsorbents. It can be suggested that ZnO/chitosan nanocomposite could serve as promising adsorbent for congo red in wastewater treatment technology.