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关键词： Chemical modification   Coating   Films   Polyethylene glycol   Starch  

摘要： This study proposes a simple route to obtain starch grafted copolymers from cassava and banana starches chemically modified with amphiphilic maleic anhydride-poly (ethylene glycol) methyl ether (Ma-mPEG). The starches were extracted from cassava (StC) and banana (StB) pulp and characterized by FTIR spectroscopy, amylose content, scanning electron microscope (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and average molecular weight. Starches were chemically modified with amphiphilic Ma-mPEG in three mass ratios 1:1, 1:2 and 1:3. Thermal behavior and interactions of Ma-mPEG/starch in the Stg-(Ma-mPEG) copolymers were studied by DSC and TGA. The T-g values showed a higher plasticizer effect in the copolymers obtained from StC. Films were formed from StC-g-(Ma-mPEG) and StB-g-(Ma-mPEG) copolymers, thermal and morphological properties were studied. An increase in the mass ratios of Ma-mPEG and the absence of the glycerol in the formulations formed homogeneous films. StC-g-(Ma-mPEG) 1:3 with 2% concentration showed a potential use as coating in strawberries, presenting a lower weight loss (15.5 +/-& nbsp;5.7%) than the control sample (18.6 +/-& nbsp;3.3%).

关键词： fused porphyrins   directly linked corroles   metal complexes   electrochemistry   magnetic properties  

摘要： Metal complexes of multi-porphyrins and multi-corroles are unique systems that display a host of extremely interesting properties. Availability of free meso and beta positions allow formation of different types of directly linked bis-porphyrins giving rise to intriguing optical and electronic properties. While the fields of metalloporphyrin and corroles monomer have seen exponential growth in the last decades, the chemistry of metal complexes of bis-porphyrins and bis-corroles remain rather underexplored. Therefore, the impact of covalent linkages on the optical, electronic, (spectro)electrochemical, magnetic and electrocatalytic activities of metal complexes of bis-porphyrins and -corroles has been summarized in this review article. This article shows that despite the (still) somewhat difficult synthetic access to these molecules, their extremely exciting properties do make a strong case for pursuing research on these classes of compounds.

关键词： Ultrasonic treatment   Red bean protein   Lutein   Interactions   Functional properties  

摘要： The complexation of red bean protein (RBP) and lutein (LU) enhances the functional properties of proteins and increases their applicability as nutraceuticals for LU. The effects of ultrasonic treatment on the interactions between RBP and LU, physicochemical properties, antioxidant activities, and digestion behaviors of RBP-LU complexes were investigated. Ultrasonic treatment promoted the non-covalent binding of RBP with LU through hydrophobic interactions, causing the binding site to be closer to tryptophan than tyrosine. This process resulted in a more flexible secondary structure and less compact tertiary conformation of complexes with higher binding ratios, surface hydrophobicity, surface charge, and smaller particle size. The enhanced RBP-LU interactions and structural modifications of complexes induced by ultrasound possibly enhanced the functional properties. Ultrasonic treatment maximized the emulsifying and antioxidant activities of these complexes, and also enhanced the release of LU in the intestine by altering the digestion behavior of the complex, thereby improving its bioaccessibility. An appropriate ultrasonic treatment could facilitate RBP-LU interactions and modify the structure of complexes to improve their functional properties.

关键词： Cow ghee   Microfluidization   Rheology   Particle size   Thermal analysis   Fourier transform infrared  

摘要： Application of microfluidization can influence physicochemical, structural, rheological and functional properties of the food matrix, significantly. In the present research, effect of high pressure microfluidization treatment (50-200 MPa, single pass) on pH, refractive index (RI), free fatty acid (FFA) values, colour measurements, rheology, particle size, structural properties and thermal properties of cow ghee (CG) were investigated. Upon microfluidization, the pH values of CG significantly increased from 4.5 to 4.9. The shear-thinning nature of microfluidized CG was demonstrated by a Rheogram between apparent viscosity and shear rate. At 50 MPa, the apparent viscosity of the sample increased but then decreased as the microfluidization pressure was increased. Thermal analysis revealed an increase in glass transition temperature (Tg) at 50 MPa from 32 to 37 C and a significant effect was observed on it as the pressure was increased. GC-MS analysis revealed that micro fluidization at 150 MPa reduced the cholesterol level in CG by 39.37%. The current research is the first one on microfluidization of CG and can open new channels on the research end.

关键词： Chemical structure   Hydrocarbons   Liquids   Physical chemistry   Surfactants  

关键词： Hydroxyapatite  

摘要： Ductal carcinoma in situ (DCIS) is frequently associated with breast calcification. This study combines multiple analytical techniques to investigate the heterogeneity of these calcifications at the micrometre scale. X-ray diffraction, scanning electron microscopy and Raman and Fourier-transform infrared spectroscopy were used to determine the physicochemical and crystallographic properties of type II breast calcifications located in formalin fixed paraffin embedded DCIS breast tissue samples. Multiple calcium phosphate phases were identified across the calcifications, distributed in different patterns. Hydroxyapatite was the dominant mineral, with magnesium whitlockite found at the calcification edge. Amorphous calcium phosphate and octacalcium phosphate were also identified close to the calcification edge at the apparent mineral/matrix barrier. Crystallographic features of hydroxyapatite also varied across the calcifications, with higher crystallinity centrally, and highest carbonate substitution at the calcification edge. Protein was also differentially distributed across the calcification and the surrounding soft tissue, with collagen and beta-pleated protein features present to differing extents. Combination of analytical techniques in this study was essential to understand the heterogeneity of breast calcifications and how this may link crystallographic and physicochemical properties of calcifications to the surrounding tissue microenvironment.

关键词： 物理化学   教学模式   微课程   虚拟实验  

摘要： 近年来,随着信息技术和互联网的迅速发展,以及移动学习和在线教育的迅速发展。物理化学实验课作为化学、化工类专业学生的必修课程,其学科特点是知识点比较抽象、实验涉及很多大型分析仪器的使用。随着学习者学习需求的不断变化,传统的实验教学模式不能达到良好的教学效果,因此迫切需要借助现代化的信息技术和手段弥补传统实验的不足。将虚拟实验微课程引入到物理化学实验课程教学过程中,采用一体化、研究式、开放式、渐进式、个性化自主式和混合式教学模式,运用多样化的教学手段,提高教学效果,培养学生创新实践能力、自主学习能力以及使其形成良好的科学素养。

关键词： Nanocomposite   Photocatalyst   Titanium dioxide   Folic acid   Antibacterial property  

摘要： In different industries, the manufacturing of antibacterial packaging is an important challenge for researchers. The goal of this project is the fabrication of antibacterial nanocomposite (NC) films based on poly(vinyl alcohol) (PVA) and titanium dioxide-folic acid (TiO2-FA) nanoparticles (NPs). Surface modification of TiO2 NPs was done with FA (as biosafe material) molecule and ultrasonic method. Various methods characterized the structure of the prepared PVA/TiO2-FA NC films. The thermogravimetric analysis displayed that the prepared PVA/TiO2-FA NC films had higher thermal stability than the neat PVA. Morphology study of the NC films showed that the TiO2-FA NPs with spherical shape had an excellent dispersion in the PVA matrices. PVA/TiO2-FA NC films had high absorption in Ultra-violet (UV)-A and UV-B regions. Also, the prepared NC film showed the lower permeability for oxygen gas compared with neat PVA. Furthermore, it was found that under UV radiation, the PVA/TiO2-FA NC films showed better antibacterial properties against Escherichia coli and Staphylococcus aureus bacteria.

关键词： 物理化学   二硝酰胺铵   ADN   晶体表面   吸湿性   表面自由能   机械感度  

摘要： 为研究二硝酰胺铵(ADN)晶体的表面性质,通过理论模拟计算探究了ADN晶体重要晶面的阴阳离子暴露数目、粗糙度、电负性和表面自由能等,并探讨了其与晶体吸湿性之间的关系;分析了ADN的键长分布,探究了引发键密度和表面自由能的关系,计算了不同晶面的引发键能量,研究了不同晶面下机械感度的大小。结果表明,当ADN表面带负电性或者电中性时吸湿性较低,表明晶体表面暴露的阴阳离子与吸湿性有关,暴露的阴离子数目越多,吸湿性越低;从晶体表面结构性质可以得出,晶体表面越光滑,吸湿性越低,感度越低;表面自由能越大,吸湿性越强;晶面的引发键密度越小、引发键能量越低,机械感度越大。其中(020)和(100)晶面光滑程度较高,表面自由能较小,引发键密度和引发键能量较大,因此吸湿性和机械感度较低。