modification

摘要： Epigenetics refers to herita ble and reversible processes regulating gene expression that do not involve a change to the DNA sequence.Epigenetic modifications include DNA modifications(e.g.DNA methylation a nd hydroxymethyl at ion),histone modifications,and non-coding RNAs such as micro RNAs and long-coding RNAs(Holtzman and Gersbach.

摘要： Tight ceramic ultrafiltration membranes have been proven to exhibit good rejection performance for reactive dye wastewater at high temperatures because of their high thermal and chemical resistance.However,the application of ceramic membranes for the treatment of cationic dye wastewater is challenging because of their surface charge.In this study,a ceramic membrane is modified by grafting aminosilane(KH-551)to enhance the positive charge of the membrane surface.The rejection performance of the charged modified ceramic membrane toward the methylene blue solution is significantly improved.The modification substance is bonded to the ceramic membrane surface via covalent bonding,which imparts good thermal stability.The modified ceramic membrane exhibits stable separation performance toward the methylene blue solution.Overall,this study provides valuable guidance for the adjustment of the ceramic membrane surface charge for treating industrial cationic dye wastewater.

摘要： The formation and application of polymeric nanomaterials is great demand in science,industry,biotechnology,and medicine due to the possibility of achieving a significant improvement in the physicochemical,mechanical,and barrier properties of polymers and using them as drug carriers and fillers,which is especially promising for biodegradable polymers such as chitosan and their derivatives.The article presents methods for creating polymer nanostructures based on polysaccharides and,in particular,chitosan.Obtaining nanostructured samples of chitosan using the approaches of chemical transformation and modification of polysaccharides is an urgent scientific problem,the solution of which makes it possible to obtain new polymer systems of great practical interest.The medical aspects of the use of polymer carriers based on chitosan for the treatment of various diseases are discussed.The unique specificity of the properties of chitosan and nanomaterials derived from it,with the properties inherent in this natural polymer,can serve as a promising future,especially in the field of medicine.

摘要： In this research,some practical aspects of densified wood glulam were investigated.For this aim,poplar wood specimens were densified by hygro-thermo-mechanical technique.Glulam specimens were produced by finger joint technique and polyurethane glue was used as resin.Physical and mechanical properties of glulams were investigated according to ASTM D 143-09,ASTM D 905-03 and ISO 8375 standards.Based on obtained results,using this process(steam and pressurize compaction)resulted in improvement of physical and mechanical prop-erties of glulam specimens.Optical microscopic and scanning electron microscopic(SEM)pictures were proved structural changes on wood material during of applied technique.Generally,the increase of wood density and hygrothermal treatment has a positive role on the glulam properties especially its dimensional stability.This tech-nique showed a significant effect on water absorption;the steaming temperature and holding time significantly decreased water absorption but densification process increased this parameter.Also,delamination of specimens was decreased by hygrothermal treatment while densification showed negative effect on delamination.Moreover,modulus of rupture,modulus of elasticity,shear strength and compression strength parallel to grain were decreased by this technique but it is depend to treatment temperature and holding time.Higher temperature and holding time cause to higher decrease in the glulam mechanical strength.

摘要： In this study,(2,2,6,6-tetramethylpiperidin-1-yl)oxyl-mediated(TEMPO-mediated)oxidized cellulose nanofibrils(TOCNFs)modified with octenyl succinic anhydride(OSA)to improve their hydrophobicity and emulsification performance were investigated.OSA loadings of 9.87-14.81 mmol/g(base on oven-dry weight of TOCNFs)were explored during modification,and the obtained OSA-modified TOCNFs(TOCNF-OSA)were characterized using Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy,X-ray diffraction,and thermogravimetric analysis.Additionally,the emulsification performance of TOCNF-OSA was also investigated in the preparation of the Pickering emulsion.The results demonstrated that the molecular chain of OSA was successfully grafted onto the backbone of TOCNFs during modification.With an increase in OSA loading,the content of the carboxyl group of the modified TOCNF-OSA increased significantly while the Zeta potential decreased.Moreover,a degree of substitution of 0.95 could be achieved at an OSA loading of 14.81 mmol/g.During the preparation of Pickering emulsions,compared with original TOCNFs,the modified TOCNF-OSA significantly improved the stability and dispersibility of the Pickering emulsion.This study demonstrated a promising approach for the modification of the Pickering emulsion to produce an eco-friendly emulsifier with superior performance for use in the food industry.

摘要： Rare earth elements(REE)are strategic resources and the recycling of REE in alternative resources is urgent and gets increasingly attention.However,the separation of REE in these alternative resources is still a challenge due to the low concentration of REE and multi coexisted ions in acidic system.In this study,the species distribution of REE within the pH 0-8.0 was calculated.The SBA-15 originated from coal fly ash was modified by two steps with(3-aminopropyl)triethoxysilane(APTES)and diethylenetriaminepentaacetic dianhydride(DTPADA)to obtain DTPADA-SBA-15 adsorbent,which was applied to the selective adsorption of REE.The results showed that DTPADA-SBA-15 possessed excellent adsorption performance on the selective adsorption of REE,including Eu,Gd,Tb,Nd and Sm,in acidic solution(pH 2)with multi competing ions.The FT-IR and Zeta potential characterization verified that the chemical adsorption through the coordination of O in DTPADA-SBA-15 with REE was dominant at lower pH value.The study of adsorption kinetics indicated that the adsorption of rare earth metal ions followed pseudosecond-order kinetic,of which the adsorption process followed the Langmuir isotherm model.

摘要： The present energy dilemma in conjunction with the adverse environmental impacts caused by fossil fuel combustion motivates researchers to seek for new renewable energy with minimal CO_(2)footprint.As a practice pathway,it is of significance to produce biofuel and platform chemicals from sustainable biomass resources.However,the research and development of high-efficiency catalysts remain one key scientific challenge.Among the catalysts developed,transition metal carbides,especially molybdenum carbide,show promising performances on biomass-based conversion.Significant efforts have been made in past few decades on tuning the structure and electronic property of molybdenum carbide via controlling particle size and morphology,metal and nonmetal doping and vacancies,etc.The review summarizes recent developments of molybdenum carbide as catalysts in converting biomass into fuel,mainly focused on the preparation methods,the structure-dependent effects and the electronic modulation.The controllable selective cleavage of C-C,C-O and C-H bonds over modified molybdenum carbides that has been demonstrated in the conversion of biomass feedstocks is then highlighted.In addition,the possible deactivation mechanisms of molybdenum carbide are also presented in the review.This review provides systematic and fundamental information for the further design and development of molybdenum carbide for the conversion of biomass resources.

摘要： The study of toxicological mechanism is an important aspect in the field of environmental and occupational health related disease control.With the progress of science and technology,the research of toxicological mechanism has made great progress.In recent years,the application of"omics"in the study of toxicological mechanisms has attracted widespread attention from scholars in the field."Omics,"such as Genomics and Proteomics[1].More and more studies have found that many important life activities and diseases are not only related to protein abundance,but more importantly are regulated by various post-translational modifications(PTMs)of proteins.In-depth study of protein post-translational modification is of great significance for revealing the mechanism of life activities,screening clinical markers of diseases,and identifying drug targets.

摘要： Nanoparticles offer unique features such as a larger surface area and enhanced electrochemical performance compared to their contemporary matters. These properties make them suitable to be considered in bridging the lacunae associated with the use of bare electrodes in electrochemical sensors. Nanomaterials enhance the redox reversibility on the electrodes’ surfaces, hence, improving the reproducibility, sensitivity, and limit of detection of the electrodes/sensors. Their methods of synthesis (top-to-bottom and bottom-to-to-top) are tailored toward manipulating their sizes, shapes, and preventing their agglomeration. This review paper provides a synopsis on research done in synthesizing nanoparticles, modifying electrodes, and pinpointing the improved performances of the modified electrodes via known characteristic techniques, namely: cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. In addition, a perspective is given in terms of increasing the lifespan of the working electrodes and the need for non-faradaic sensors.

摘要： With the discovery of the“central dogma”of life science,the molecular mechanism of genetics and evolution of biological species has basically been established.However,the completion of the Human Genome Project at the turn of the 21st century has begun to uncover the complexity of individual lives.Although the evolution of living individuals depends mainly on the sequence of genes,its complexity and diversity cannot be explained by the“central dogma”alone.Biomolecules,including proteins,nucleic acids and polysaccharides,are the basic“building blocks”of life,providing the material basis for living processes,and are subject to dynamic chemical modifications and regulation.The dynamic chemical modifications of these biomolecules play a key role in the development of individual organisms and in the regulation of cell fate,and also play a decisive role in the onset and development of diseases.

摘要： A series of novel hyperbranched polyurethane acrylate oligomers containing photoinitiator weresynthesized by modifying the second generation hyperbranched polyester with isophoronediisocyanate-2-hydroxyethylacrylate (IPDI-HEA) and isophoronediisocyanate-2-hydroxy-2-methylpropiophenone (IPDI-HMPP) at different feed ratio. The structure of theobtained oligomers was characterized by FT-IR,1H-NMR and elemental analysis. The molecular weights andpolydispersities of the oligomers were analyzed by GPC and shown narrow distribution. UV–Vis spectraresults showed that the maximum absorption bands of these oligomers are at around 325nm. UV-curingproperties were characterized by FT-IR at different curing time. The thermal properties of the oligomers werealso studied by TGA. The results showed that the UV-cured films have good thermal stability.

摘要： A series of novel hyperbranched polyurethane acrylate oligomers containing photoinitiator weresynthesized by modifying the second generation hyperbranched polyester with isophoronediisocyanate-2-hydroxyethylacrylate (IPDI-HEA) and isophoronediisocyanate-2-hydroxy-2-methylpropiophenone (IPDI-HMPP) at different feed ratio. The structure of theobtained oligomers was characterized by FT-IR,1H-NMR and elemental analysis. The molecular weights andpolydispersities of the oligomers were analyzed by GPC and shown narrow distribution. UV–Vis spectraresults showed that the maximum absorption bands of these oligomers are at around 325nm. UV-curingproperties were characterized by FT-IR at different curing time. The thermal properties of the oligomers werealso studied by TGA. The results showed that the UV-cured films have good thermal stability.

摘要： A series of novel hyperbranched polyurethane acrylate oligomers containing photoinitiator weresynthesized by modifying the second generation hyperbranched polyester with isophoronediisocyanate-2-hydroxyethylacrylate (IPDI-HEA) and isophoronediisocyanate-2-hydroxy-2-methylpropiophenone (IPDI-HMPP) at different feed ratio. The structure of theobtained oligomers was characterized by FT-IR,1H-NMR and elemental analysis. The molecular weights andpolydispersities of the oligomers were analyzed by GPC and shown narrow distribution. UV–Vis spectraresults showed that the maximum absorption bands of these oligomers are at around 325nm. UV-curingproperties were characterized by FT-IR at different curing time. The thermal properties of the oligomers werealso studied by TGA. The results showed that the UV-cured films have good thermal stability.

摘要： A series of novel hyperbranched polyurethane acrylate oligomers containing photoinitiator weresynthesized by modifying the second generation hyperbranched polyester with isophoronediisocyanate-2-hydroxyethylacrylate (IPDI-HEA) and isophoronediisocyanate-2-hydroxy-2-methylpropiophenone (IPDI-HMPP) at different feed ratio. The structure of theobtained oligomers was characterized by FT-IR,1H-NMR and elemental analysis. The molecular weights andpolydispersities of the oligomers were analyzed by GPC and shown narrow distribution. UV–Vis spectraresults showed that the maximum absorption bands of these oligomers are at around 325nm. UV-curingproperties were characterized by FT-IR at different curing time. The thermal properties of the oligomers werealso studied by TGA. The results showed that the UV-cured films have good thermal stability.