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201.
Characterization of a formaldehyde-free cornstarch-tannin wood adhesive for interior plywood 总被引:4,自引:0,他引:4
Amine Moubarik Ahmed Allal Antonio Pizzi Fatima Charrier Bertrand Charrier 《Holz als Roh- und Werkstoff》2010,68(4):427-433
This study investigated the physical properties (rheological and thermogravimetric analysis) of cornstarch-tannin adhesives and the mechanical properties (dry tensile strength and 3-point bending strength) of plywood made using cornstarch-tannin adhesives. This adhesive was evaluated for its utility in interior plywood manufacture. The optimum cure temperature and cure time of cornstarch-tannin adhesives were 170°C and 4?min, respectively. Plywood bonded with formaldehyde-free cornstarch-tannin adhesive exhibited excellent mechanical properties comparable to commercially available phenol-formaldehyde plywood adhesives. It was found that cornstarch-tannin panels which do not contain formaldehyde and with an emission equal to that of heated but unbound wood can be obtained by the use of hexamethylenetetramine (hexamine) as hardener. The work has indicated that an environmentally friendly wood adhesive can be prepared from a natural renewable resource (cornstarch and wattle tannin) for bonding interior-type plywood. 相似文献
202.
Isotactic polypropylene (iPP) and iron oxide (Fe3O4) nanocomposites were mixed by masterbatch blending technique in a single screw extruder machine. The concentrations of Fe3O4 in the iPP/Fe3O4 nanocomposites were 0.5, 1, 2, and 5% by weight. The influence of Fe3O4 nanoparticles on the effectiveness of nucleation, morphology, mode of crystallization, and crystallinity of iPP were studied by differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The introduction of Fe3O4 nanoparticles in the iPP matrix inhibited the formation of β crystals, and caused a shift in the melting point to higher values. The magnitude of the shift was up to 20–21°C which indicates that using the masterbatch technique leads to an enhancement of the dispersion process of the Fe3O4 nanoparticle and the formation of less agglomerates in the iPP/Fe3O4 nanocomposites. The percentage crystallinity, Xc, increased at the low cooling rates of 1 and 2°C/min. At higher cooling rates of 5, 10, and 20°C/min, the masterbatch technique produced nanocomposites of Xc with nonuniform trends. The overall crystallization rate enhancement for the iPP/Fe3O4 nanocomposites is attributed to the presence of Fe3O4 nanoparticles as a nucleating agent which have no significant effect on the growth rate of iPP crystals. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
203.
204.
Fatima Toor Jihun Oh Howard M. Branz 《Progress in Photovoltaics: Research and Applications》2015,23(10):1375-1380
We produce low‐reflectivity nanostructured ‘black’ silicon (bSi) using copper (Cu) nanoparticles as the catalyst for metal‐assisted etching and demonstrate a 17.0%‐efficient Cu‐etched bSi solar cell without any vacuum‐deposited anti‐reflection coating. The concentration ratio of HF to H2O2 in the etch solution provides control of the nanostructure morphology. The solar‐spectrum‐weighted average reflection (Rave) for bSi is as low as 3.1% on Cu‐etched planar samples; we achieve lower reflectivity by nanostructuring of micron‐scale pyramids. Successful Cu‐based anti‐reflection etching requires a concentration ratio [HF]/[H2O2] ≥ 3. Our 17.0%‐efficient Cu‐etched bSi photovoltaic cell with a pyramid‐texture has a Rave of 3% and an open circuit voltage (Voc) of 616 mV that might be further improved by reducing near‐surface phosphorus (P) densities. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
205.
The effects of changes in marital status on the changes in depressive symptoms of 443 African American mothers from the National Longitudinal Survey of Youth 1979 (NLSY) were examined. Results showed that those mothers who exited marriage increased in depressive symptoms relative to continuously married and newly married mothers. Moreover, mothers who entered marriage later experienced the same level of depressive symptoms as continuously married mothers. However, financial resources moderated the effects of marital transitions. Those mothers with more financial resources did not experience an increase in depressive symptoms after divorce, but those with fewer resources experienced a large increase. It was concluded that divorce is a risk factor for mental health concerns among African American mothers, but financial resources serve as a protective factor. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
206.
Pakistan's readymade garments' industry is a key player in Pakistan's industry in general, and its textile industrial output and exports in particular. In a liberalizing international trade regime, quality will be a critical success factor in the international competitiveness of Pakistan's readymade garments. Research in quality management in Pakistan's readymade garments' industry was undertaken. To gain further information, a postal self-completion questionnaire was mailed to 101 members of the Pakistan Readymade Garments' and Exporters' Association (PRGMEA). The response rate was 32%. It was found that while this industrial segment was in various stages of development, it needs to graduate fast to advanced quality management concepts of Kaizen and total quality management in order to maintain its competitive advantage in an environment that will soon be liberalized fully. 相似文献
207.
Fatima Bousejra‐El Garah Jean‐Luc Stigliani Dr. Frédéric Coslédan Dr. Bernard Meunier Dr. Anne Robert Dr. 《ChemMedChem》2009,4(9):1469-1479
PfATP6, a calcium‐dependent ATPase of Plasmodium falciparum, is considered the putative target of the antimalarial drug artemisinin and its derivatives. Herein, the 3D structure of PfATP6 was modeled on the basis of the crystal structure of SERCA 1a, the mammalian homologue. Model validation was achieved using protein structure checking tools. AutoDock4 was used to predict the binding affinities of artemisinin (and analogues) and various other antimalarial agents for PfATP6, for which in vitro activity is also reported. No correlation was found between the affinity of the compounds for PfATP6 predicted by AutoDock4 and their antimalarial activity. 相似文献
208.
Tam Minh Le Thu Huynh Fatima Zahra Bamou Andrs Szekeres Ferenc Fülp Zsolt Szakonyi 《International journal of molecular sciences》2021,22(11)
Discovery of novel antibacterial agents with new structures, which combat pathogens is an urgent task. In this study, a new library of (+)-neoisopulegol-based O-benzyl derivatives of aminodiols and aminotriols was designed and synthesized, and their antimicrobial activity against different bacterial and fungal strains were evaluated. The results showed that this new series of synthetic O-benzyl compounds exhibit potent antimicrobial activity. Di-O-benzyl derivatives showed high activity against Gram-positive bacteria and fungi, but moderate activity against Gram-negative bacteria. Therefore, these compounds may serve a good basis for antibacterial and antifungal drug discovery. Structure–activity relationships were also studied from the aspects of stereochemistry of the O-benzyl group on cyclohexane ring and the substituent effects on the ring system. 相似文献
210.
Tasnim Fatima Nasrin Arab Evgeny P. Zemskov Adrian Muntean 《Journal of Engineering Mathematics》2011,69(2-3):261-276
A reaction?Cdiffusion system modeling concrete corrosion in sewer pipes is discussed. The system is coupled, semi-linear, and partially dissipative. It is defined on a locally periodic perforated domain with nonlinear Robin-type boundary conditions at water?Cair and solid?Cwater interfaces. Asymptotic homogenization techniques are applied to obtain upscaled reaction?Cdiffusion models together with explicit formulae for the effective transport and reaction coefficients. It is shown that the averaged system contains additional terms appearing due to the deviation of the assumed geometry from a purely periodic distribution of perforations for two relevant parameter regimes: (a) all diffusion coefficients are of order of ${\mathcal{O}(1)}$ and (b) all diffusion coefficients are of order of ${\mathcal{O}(\varepsilon^2)}$ except the one for H2S(g) which is of order of ${\mathcal{O}(1)}$ . In case (a) a set of macroscopic equations is obtained, while in case (b) a two-scale reaction?Cdiffusion system is derived that captures the interplay between microstructural reaction effects and the macroscopic transport. 相似文献