Poly(vinyl alcohol)/chitosan oligosaccharide blend submicrometer fibers prepared from aqueous solutions by the electrospinning method

Submicrometer fibers of poly(vinyl alcohol) (PVA) and chitosan oligosaccharide [COS; i.e., (1→4)‐2‐amino‐2‐deoxy‐β‐D ‐glucose] were prepared by an electrospinning method with aqueous solutions with polymer concentrations of 7.5–15 wt %. Scanning electron microscopy, Fourier transform infrared, X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis were used to characterize the morphology and properties of the PVA/COS fibers. The PVA/COS mass ratio, the total polymer concentration, and processing parameters such as the applied voltage and capillary‐to‐collector distance played important roles in controlling the fiber morphology. Fourier transform infrared and X‐ray diffraction data demonstrated that there were possibly hydrogen bonds between COS and PVA molecules that weakened the interactions in COS and improved the electrospinnability of PVA/COS. Moreover, with a higher percentage of COS in the PVA/COS blend fibers, superior thermal stability could be obtained. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Electrospinning fabrication and characterization of poly(vinyl alcohol)/montmorillonite nanofiber mats

Poly(vinyl alcohol) (PVA)/montmorillonite clay (MMT) nanofiber mats have been fabricated by the electrospinning technique. The PVA/MMT nanofiber mats were characterized by X‐ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and mechanical measurements. The study showed that the introduction of MMT results in improvement in tensile strength, and thermal stability of the PVA matrix. XRD patterns and SEM micrographs suggest the coexistence of exfoliated MMT layers over the studied MMT contents. FTIR revealed that there might be possible interaction occurred between the MMT clay and PVA matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Investigation of PRDM10 and PRDM13 Expression in Developing Mouse Embryos by an Optimized PACT-Based Embryo Clearing Method

Recent developments in tissue clearing methods have significantly advanced the three-dimensional analysis of biological structures in whole, intact tissue, providing a greater understanding of spatial relationships and biological circuits. Nonetheless, studies have reported issues with maintaining structural integrity and preventing tissue disintegration, limiting the wide application of these techniques to fragile tissues such as developing embryos. Here, we present an optimized passive tissue clearing technique (PACT)-based embryo clearing method, initial embedding PACT (IMPACT)-Basic, that improves tissue rigidity without compromising optical transparency. We also present IMPACT-Advance, which is specifically optimized for thin slices of mouse embryos past E13.5. We demonstrate proof-of-concept by investigating the expression of two relatively understudied PR domain (PRDM) proteins, PRDM10 and PRDM13, in intact cleared mouse embryos at various stages of development. We observed strong PRDM10 and PRDM13 expression in the developing nervous system and skeletal cartilage, suggesting a functional role for these proteins in these tissues throughout embryogenesis.     

TSA Promotes CRISPR/Cas9 Editing Efficiency and Expression of Cell Division-Related Genes from Plant Protoplasts

Trichostatin A (TSA) is a representative histone deacetylase (HDAC) inhibitor that modulates epigenetic gene expression by regulation of chromatin remodeling in cells. To investigate whether the regulation of chromatin de-condensation by TSA can affect the increase in the efficiency of Cas9 protein-gRNA ribonucleoprotein (RNP) indel formation from plant cells, genome editing efficiency using lettuce and tobacco protoplasts was examined after several concentrations of TSA treatments (0, 0.1, 1 and 10 μM). RNP delivery from protoplasts was conducted by conventional polyethylene glycol (PEG) transfection protocols. Interestingly, the indel frequency of the SOC1 gene from TSA treatments was about 3.3 to 3.8 times higher than DMSO treatment in lettuce protoplasts. The TSA-mediated increase of indel frequency of the SOC1 gene in lettuce protoplasts occurred in a concentration-dependent manner, although there was not much difference. Similar to lettuce, TSA also increased the indel frequency by 1.5 to 1.8 times in a concentration-dependent manner during PDS genome editing using tobacco protoplasts. The MNase test clearly showed that chromatin accessibility with TSA treatments was higher than that of DMSO treatment. Additionally, TSA treatment significantly increased the level of histone H3 and H4 acetylation from lettuce protoplasts. The qRT-PCR analysis showed that expression of cell division-related genes (LsCYCD1-1, LsCYCD3-2, LsCYCD6-1, and LsCYCU4-1) was increased by TSA treatment. These findings could contribute to increasing the efficiency of CRISPR/Cas9-mediated genome editing. Furthermore, this could be applied for the development of useful genome-edited crops using the CRISPR/Cas9 system with plant protoplasts.     

Synthesis and characteristics of interpenetrating polymer network hydrogel composed of chitosan and poly(acrylic acid)

Interpenetrating polymer network (IPN) hydrogels composed of chitosan and poly(acrylic acid) (PAAc) were synthesized by UV irradiation method, and their structure, crystallinity, swelling behavior, thermal property, and mechanical property were investigated. Chitosan/PAAc IPNs exhibited relatively high equilibrium water content and also showed reasonable sensitivity to pH. From the swelling behaviors at various pH's, Fourier transform infrared spectra at high temperature and thermal analysis confirmed the formation of polyelectrolyte complex due to the reaction between amino groups in chitosan and carboxyl groups in PAAc. For this reason, even at a swollen state, the present chitosan/PAAc IPNs possess good mechanical properties. Particularly, the CA‐2 sample (with a weight ratio of chitosan/PAAc = 50/50, molar ratio [NH₂]/[COOH] = 25/75) showed the lowest equilibrium water content and free water content, attributed to the more compact structure of the polyelectrolyte than CA‐1 or CA‐3 due to the high amount of interchain bond within the IPN. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 113–120, 1999     

Evaluation of drum bioreactor performance used for decontamination of soil polluted with polycyclic aromatic hydrocarbons

A laboratory‐scale drum bioreactor system was used to study engineering aspects of soil bioremediation. Polycyclic aromatic hydrocarbons (PAHs) were chosen as contaminants in soil. In the operation of the reactor, different mixing strategies were applied according to the size of soil without separate washing of sand. The effect of the water content of the soil mixture on solid mixing time and phenanthrene degradation rate was of particular interest. At 20% water content, which was below the saturation level, the mixing efficiency of soil and the degradation rate of phenanthrene was lower than those at 30% or 40% water content. Optimal water content was variable according to the soil texture. The drum bioreactor was operated under optimal water content and PAH concentration (fluorene, phenanthrene, anthracene, pyrene) and microbial numbers were measured in each soil phase (sediment and suspension). Over 95% of PAHs with three or four rings (fluorene, phenanthrene, anthracene, pyrene) were degraded at 270 mg kg⁻¹ soil within 20 days. The degradation rate of PAHs in the suspension phase was higher than that in sediment phase. © 1999 Society of Chemical Industry     

Hydrogen production from wastewater using a microbial electrolysis cell

A Microbial electrolysis cell (MEC) was designed to produce a useful and valuable product, hydrogen gas, during the wastewater treatment process. Hydrogen can be produced using the MEC with an applied voltage of over 0.4 V, and the hydrogen yields gradually increased with the increasing of applied voltage. A maximum overall hydrogen efficiency of 21.2% was achieved at an applied voltage of 1.0 V with acetate as substrate, corresponding to a volumetric hydrogen production rate of approximately 0.095 m³ H₂/m³ reactor liquid volume/day. A volumetric hydrogen production rate of 0.061 m³ H₂/m³ reactor liquid volume/day was achieved when piggery wastewater was fed to the MEC, and the chemical oxygen demand removal rate ranged from 45 to 52%. The results demonstrated that the wastewater, especially an organic-rich item such as piggery wastewater, could be feasibly treated based on this MEC system.     

A comparative study on the recovery of 1,2-dichloroethane and the removal of benzene contained in the byproducts of VCM process

A comparative study has been performed to compare initial investment costs and operation costs for two different process configurations. The two processes were used to recover 1,2-dichloroethane (EDC) and to remove benzene contained in the byproducts of the vinyl chloride monomer (VCM) process. The objectives of this process were to recover 70% of EDC contained in the byproducts and to reduce the benzene content below 0.7 wt%. The first process configuration for comparison is a conventional distillation column that consists of upper and lower columns. The other process configuration is an extractive distillation process that uses Normal Formyl Morpholine (NFM) as a solvent to remove benzene. The conventional distillation process which consists of upper and lower distillation columns was superior to the extractive distillation process, which used a solvent, in the aspects of the initial investment and annual operating cost.     

Polymeric nanoparticles,micelles and polymersomes from amphiphilic block copolymer

Block copolymers are made up of blocks of different polymerized monomers. Among the block copolymers, amphiphilic block copolymers can self-assemble to form nano-sized vehicles, such as micelles, nanoparticles, polymersomes, in aqueous or non-aqueous media. This review describes the synthesis, formation, and major applications of amphiphilic block copolymer and corresponding vehicles in order to provide an overview of the current features of functionalized block copolymers for drug delivery applications.