Polyamide 6 composite fibers with incorporated mixtures of melamine cyanurate,carbon nanotubes,and carbon black

Polyamide 6 (PA6) composite filament yarns were produced by the simultaneous incorporation of melamine cyanurate (MeCy) with multiwalled carbon nanotubes (CNTs) and carbon black (CB) into a composite matrix in a melt-spinning process. The results show that the simultaneous incorporation of MeCy with CNTs or CB additives provided filaments with a uniform black color. Tensile analysis confirmed that a reinforcing effect was achieved when CB was used, whereas the CNTs induced a reducing effect on the filament tenacity. With regard to the burning behavior, the flame-retardant action of MeCy was preserved in the presence of CB but was significantly hindered when used in combination with CNTs. These results indicate that the mixture of MeCy and CB was much more compatible for the production of reinforced PA6 composite filaments with increased thermal stability and improved flame retardancy over those of the MeCy and CNTs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47007.     

Wide range humidity sensors printed on biocomposite films of cellulose nanofibril and poly(ethylene glycol)

Cellulose nanofibril (CNF) films were prepared from side streams generated by the sugarcane industry, that is, bagasse. Two fractionation processes were utilized for comparison purposes: (1) soda and (2) hot water and soda pretreatments. 2,2,6,6-Tetramethylpiperidinyl-1-oxyl-mediated oxidation was applied to facilitate the nanofibrillation of the bagasse fibers. Poly(ethylene glycol) (PEG) was chosen as plasticizer to improve the ductility of CNF films. The neat CNF and biocomposite films (CNF and 40% PEG) were used for fabrication of self-standing humidity sensors. CNF-based humidity sensors exhibited high change of impedance, within four orders of magnitude, in response to relative humidity (RH) from 20 to 90%. The use of plasticizer had an impact on sensor kinetics. While the biocomposite film sensors showed slightly longer response time, the recovery time of these plasticized sensors was two times shorter in comparison to sensors without PEG. This study demonstrated that agroindustrial side streams can form the basis for high-end applications such as humidity sensors, with potential for, for example, packaging and wound dressing applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47920.     

The effect of composition of a polymeric coating on the biofilm formation of bacteria and filamentous fungi

Functionality of polymeric coating, especially in terms of anti-corrosive properties and stability, can be negatively influenced by formation of either bacterial or fungal biofilm on its surface. Herein, the epoxy-ester resin based polymeric coating was filled with pigments (natural silicon dioxide diatomite, natural wollastonite, tungstate and molybdate). Pigments was modified by conducting polymers (polyaniline phosphate, polypyrrole phosphate, poly(p-phenylenediamine) phosphate and ZnFe₂O₄). Impact of modified pigments on the surface energy and formation of biofilm were tested. The use of various biofilm forming species of both the bacteria and fungi filled a knowledge gap about their behavior on polymeric coatings.     

表面活性剂改性磁性氧化石墨烯共价固定脂肪酶CRL

采用化学共沉淀法制备磁性氧化石墨烯（MGO）,直接在反应体系中加入Span系列表面活性剂,一锅法制备得到表面活性剂改性磁性氧化石墨烯（SMGO）。X射线衍射仪（XRD）、扫描电镜（SEM）和傅里叶变换红外光谱（FTIR）表征结果表明SMGO制备成功,且具有良好的磁分离性能。以1,5-戊二醛（GA）为交联剂,褶皱假丝酵母脂肪酶（CRL）为模型酶,共价固定CRL于SMGO载体上。Span40 MGO固定化酶酶活回收率为116.5%±1.7%,为MGO固定化酶的6倍;比活可达32.5U/mg,为游离酶的1.6倍;k_cat/K_m也有较大的提升,高于游离酶50%。储存稳定性及热稳定性得到提高,用于水解反应6批次后仍然保留73.6%的相对酶活力。初步分析认为MGO经改性后表面从亲水性转为强疏水性,使得共价固定化过程中同时发生疏水性界面活化,这是酶活性提高的原因之一。文章所报道的改性策略可为类似载体改性提供新思路。     

燃煤循环流化床锅炉急冷脱硫底渣作为水泥混合材的性能

针对循环流化床锅炉（CFB）底渣利用率偏低的问题,提出一种新的底渣处理应用方案——对底渣进行急冷处理后,将其作为脱硫剂或水泥混合材进行综合利用。本文通过搭建CFB锅炉底渣急冷实验系统,制备了不同渣温下的急冷底渣样品;然后选取亿利底渣和42.5标号的水泥作为研究对象,探讨了急冷底渣作混合材对水泥性能的影响。实验结果表明：急冷会破坏底渣颗粒形状,导致外壳成分发生变化。急冷处理不仅造成CaSO₄峰值显著降低,而且使得Ca(OH)₂的特征峰变强。在相同的CFB底渣掺比下,与原始底渣相比,急冷底渣作为水泥混合材时,虽然无助于提高抗折抗压强度,但能缩短凝结时间,减少安定性值。同时,还能减少水泥标准稠度需水量,提升水泥的密实程度,对水泥的力学性能和抗侵蚀性有着一定的积极作用。     

The comprehensive in vitro evaluation of eight different calcium phosphates: Significant parameters for cell behavior

Eight different calcium phosphate nanoparticles, namely bovine bone bioapatite calcined at 500, 600, and 700°C, Mg-doped brushite, fluorinated calcium phosphate, Ca-deficient hydroxyapatite, hydroxyapatite, and tricalcium phosphate, were characterized employing physico-chemical methods. Their cytocompatibility was evaluated under human osteoblast-like cell line MG-63 culture conditions in elution media and via the direct interaction of cells with calcium phosphate nanoparticles. The main objective was to determine the correlation of the cell indices with the differently determined physical and chemical parameters of the calcium phosphates. Chemical composition, which contributes toward pH changes, and the calcium ion concentration in the medium appear to make up particularly significant factors; moreover, it was proved that the number of material types represents a further important aspect. In the case of a large number of material types, almost no correlation was determined between the analyzed parameters; however, in the case of a small number of apatite types, several positive correlations were found. It can be concluded that it is not possible to identify any monitored parameters that had a major impact on cell behavior or, at least, such an effect which can be generalized. It appears more likely that cell behavior is affected by the interplay of various parameters.     

Single-step preparation of rutile-type CrNbO4 and CrTaO4 oxides from oxalate precursors–characterization and properties

Chromium niobate and tantalate (CrNbO₄ and CrTaO₄) were synthesized by pyrolysis of the oxalate-based heterometallic complexes [Cr₂(bpy)₄(μ-O)₄Nb₂(C₂O₄)₄]·3H₂O (Cr-Nb) and [Cr(bpy)₂(H₂O)(μ-O)Ta(C₂O₄)₃]₂·3.5H₂O (Cr-Ta) (bpy = 2,2'-bipyridine). Compared to conventional solid-state synthesis, herein studied oxides are prepared at lower temperatures, in one step without repeating grinding procedures. The structure, morphology, and optical properties of the as-synthesized oxides were characterized using powder X-ray diffraction (PXRD), field emission scanning electron microscopy (SEM), the thermogravimetric and differential thermal analysis (TG/DTA) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The determined band gap energies of CrNbO₄ and CrTaO₄ are 2.39 and 2.82 eV, respectively, which prompted us to investigate photocatalytic activity of these oxides in degradation of dyes. Microscopy studies show that the particles of both oxides began to aggregate into bigger particles, leading to an increase in grain size. Additionally, magnetization measurements on both oxides revealed spin-glass behavior at low temperatures.     

Structure and enhanced antimicrobial activity of mechanically activated nano TiO2

Titanium dioxide is a photocatalyst, known not only for its ability to oxidize organic contaminants, but also for its antimicrobial properties. In this article, significant enhancement of the antimicrobial activity of TiO₂ (up to 32 times) was demonstrated after its activation by ball milling. The antimicrobial activity was analyzed for one fungal and 13 bacterial ATCC strains using the microdilution method and recording the minimum inhibitory concentration (MIC) values. In order to further investigate the correlation between the mechanical activation of TiO₂ and its antimicrobial activity, the structure, morphology and phase composition of the material were studied by means of Electron Microscopy, X-ray diffraction and nitrogen adsorption-desorption measurements. UV-Vis diffuse reflectance spectra were recorded and the Kubelka-Munk function was applied to convert reflectance into the equivalent band gap energy (E_g) and, consequently, to investigate changes in the E_g value. X-ray photoelectron spectroscopy was used to analyze the influence of mechanical activation on the Ti 2p and O 1s spectra. The presented results are expected to enable the development of more sustainable and effective advanced TiO₂-based materials with antimicrobial properties that could be used in numerous green technology applications.     

An improved gray line profile method to inspect the warp–weft density of fabrics

Image processing has become a tremendous tool for various fields of applications as well as for textile manufacturing industry in recent years. Inspection of fabric density is one of the major issues for fabric manufacturers in textile industries. In this study, an image processing method comprising of linear and nonlinear techniques for automatic inspection of warp and weft yarn density of fabrics has been proposed. By avoiding common problems of linear filtering such as blurring and localization, anisotropic diffusion filtering has been applied as preprocessing operation to enhance the edge region/boundaries between adjacent yarns of the fabric images. We conjecture that given a skewed gray level image, the number of peaks in the gray line profile of the image is minimized if the image is rotated in such a way that the inter-spaces between yarns are aligned with the vertical axis. Gabor filter, an orientation-sensitive filter, is applied to the skewed image at that angle to boost the edges between inter-spaces. The number of warp and weft yarn density has been inspected by applying gray line profile method. Simulations have been done on a wide range of fabric image data set. The results have shown that nonlinear and steered filters made a contribution to the performance of the method. The number warp and weft yarn densities are determined with an accuracy rates above 90%.     

Performance of wood impregnated with N-methylol and copper based aqueous solutions

The combination of copper and N-methylol compounds considerably improves the performance against copper sensitive fungi (G. trabeum and T. versicolor), while the fungicidal effect against copper tolerant strain (A. vaillantii) remained insufficient. Addition of N-methylol compounds to copper solution significantly reduces leaching from wood blocks impregnated with the solution of the lowest copper concentration (c_Cu =0.1%), and less notably reduces leaching from wood blocks impregnated with solutions of higher copper contents (c_Cu=0.5%).