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Poly(butylene succinate‐co‐butylene adipate)/polyethylene oxide blends for controlled release materials: A morphological study 下载免费PDF全文
Amandine Cottaz Fadi Khalil Sophie Galland Fouzia Jbilou Isabelle Adt Pascal Degraeve Catherine Joly 《应用聚合物科学杂志》2016,133(3)
Varying the formulation and processing conditions of polymer blends allows the design of materials with a large range of morphologies. Active materials embedding active compounds in a devoted phase are promising applications of such blends, offering possible various transport properties. In this study, 13 poly(butylene succinate‐co‐butylene adipate) (PBSA)/polyethylene oxide (PEO) blends were extruded in a slit die. Their morphologies were characterized by water extraction (selective PEO dissolution), FTIR spectroscopy, and differential scanning calorimetry. Transport properties were assessed by water vapor permeation and fluorescein release as model migrant. Indeed, the desorption in water of fluorescein (previously entrapped in PEO) was monitored to preliminary investigate the release properties of these materials: two morphologies were obtained (i) pseudo multilayer films made of PEO‐rich layer/PBSA‐rich layer/PEO‐rich layer and (ii) PEO nodules dispersed in the PBSA‐rich matrix for the highest PBSA contents. The first systems were erodible ones with an uncontrolled fast delivery by PEO dissolution whereas the second ones showed a controlled release by permeation through the PBSA matrix from PEO nodules. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42874. 相似文献
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The RecQ-related family of DNA helicases is required for the maintenance of genomic stability in organisms ranging from bacteria to humans. In humans, mutation of three RecQ-related helicases, BLM, WRN and RecQL4, cause the cancer-prone and premature ageing diseases of Bloom syndrome, Werner's syndrome and Rothmund-Thompson syndrome, respectively. In the fission yeast Schizosaccharomyces pombe, disruption of the rqh1(+) gene, which encodes the single Sz. pombe RecQ-related helicase, causes cells to display reduced viability and elevated levels of chromosome loss. After S-phase arrest or DNA damage, cells lacking rqh1(+) function display elevated levels of homologous recombination and defective chromosome segregation. Here we show that, like other RecQ family members, the Rqh1p protein displays 3' to 5' DNA helicase activity. Interestingly, however, unlike other RecQ family members, the helicase activity of Rqh1p is only partially required for its function in recovery from S-phase arrest or DNA damage. We also report that high cellular levels of Rqh1p result in lethal chromosome segregation defects, while more moderate levels of Rqh1p cause significantly elevated rates of chromosome loss. This suggests that careful regulation of RecQ-like protein levels in eukaryotic cells is vital for maintaining genome stability. 相似文献
3.
Fouzia Belaib Mokri AzzedineBoukellal Boubeker Meniai Abdeslam-Hassen 《International Journal of Hydrogen Energy》2014
The release of drugs and their metabolites into the environment is of a great concern, as far as the water pollution is concerned. One can cite oxytetracycline which is used in large quantities and it is essential to reduce its presence in aquatic environments. 相似文献
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Rifaqat Ali Khan Rao Moonis Ali Khan Fouzia Rehman 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2010,156(1):106-113
This work presents the biosorption potential of Fennel biomass for the effective removal of Cd(II) ions. The biosorption was maximum (92%) at pH 4.3. Maximum biosorption capacities of Cd(II) at 30, 40 and 50 °C temperatures were 21, 24 and 30 mg/g, respectively. The biosorption of Cd(II) was concentration dependent and increases from 0.49 to 9.3 mg/g with increase in concentration from 5 to 100 mg/L. Biosorption follows Freundlich isotherm at 50 °C. Mean free energies at different temperatures were in between 7.1 and 11.95 kJ/mol indicating chemical nature of biosorption process. Kinetics studies showed that pseudo-second-order kinetics model was applicable to the data. The process was endothermic and spontaneous, the spontaneity of the process increases with increase in temperature. Regeneration studies showed a decrease in the recovery of Cd(II) from 99.8% to 41.7% in five consecutive cycles. 80% of the Cd(II) in single and multi-metal systems was recovered in 10 mL. Breakthrough and exhaustive capacities of Cd(II) in single metal system were 10 and 40 mg/g. For multi-metal systems in double distilled water the breakthrough and exhaustive capacities of Cd(II) were 2 and 12 mg/g. In saline solution the breakthrough and exhaustive capacities of Cd(II) were 0.8 and 4 mg/g. 相似文献
5.
In this paper, experiments to investigate fibrous insulating materials used in buildings have been performed. Two kinds of glass fibers based products were studied. Scanning electron microscopy (SEM) coupled with an EDX detector, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and X-ray diffraction diagnostic method were used to assess materials properties. Through the coupling of thermal analyses with morphological and structural characterization techniques, a fast and safer comparison between the insulators becomes possible. So, after being tested at various rates of humidities, it is shown that the aim cause of ageing in the glass wools studied is mainly due to their binders. In fact, the alteration of glass constituting fibers comes much later. Besides, there is no preferential orientation for the vapor transfer inside glass wools. 相似文献
6.
Fouzia Hussain Shagufta Kamal Saima Rehman Muhammad Azeem Ismat Bibi Tanvir Ahmed Hafiz M. N. Iqbal 《Catalysis Letters》2017,147(5):1204-1213
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Andreas Reisch Patricia Tirado Emilie Roger Fouzia Boulmedais Dominique Collin Jean‐Claude Voegel Benoît Frisch Pierre Schaaf Joseph B. Schlenoff 《Advanced functional materials》2013,23(6):673-682
Durable compact polyelectrolyte complexes (CoPECs) with controlled porosity and mechanical properties are prepared by ultracentrifugation. Because the starting materials, poly(allylamine hydrochloride) (PAH) and poly(acrylic acid sodium salt) (PAA), are weak acids/bases, both composition and morphology are controlled by solution pH. In addition, the nonequilibrium nature of polyelectrolyte complexation can be exploited to provide a range of compositions and porosities under the influence of polyelectrolyte addition order and speed, and concentration. Confocal microscopy shows these “saloplastic” materials to be highly porous, where pore formation is attributed to a combination of deswelling of the polyelectrolyte matrix and expansion of small inhomogenities by osmotic pressure. The porosity (15–70%) and the pore size (<5 μm to >70 μm) of these materials can be tuned by adjusting the PAA to PAH ratio, the salt concentration, and the pH. The modulus of these CoPECs depends on the ratio of the two polyelectrolytes, with stoichiometric complexes being the stiffest due to optimized charge pairing, which correlates with maximized crosslinking density. Mechanical properties, pore sizes, and pore density of these materials make them well suited to three dimensional supports for tissue engineering applications. 相似文献
9.
Selma Limam Mansar Hajo A. Reijers Fouzia Ounnar 《Expert systems with applications》2009,36(2):3248-3262
To support the efficient appraisal of and selection from a list of generic business process improvement principles, this paper proposes a strategy for the implementation of business process redesign (BPR). Its backbone is formed by the analytic hierarchy process (AHP) multicriteria method and our earlier research into the popularity and impact of a set of redesign “best practices”. Using AHP, we derive a classification of most suitable directions for a particular process to be redesigned. Criteria such as the popularity, the impact, the goals and the risks of BPR implementation are taken into account. A case study is included to demonstrate the method’s feasibility and effectiveness. 相似文献
10.
Fouzia Adjadj El-djemai Belbacha Malek Bouharkat 《Journal of Alloys and Compounds》2007,430(1-2):85-91
The experimental study of the system Sb–Zn by differential calorimetry made it possible to plot the whole phase diagram. We found the stability domains of existence of the stoichiometric compound SbZn and the solid solutions which extend on both sides from the compositions corresponding to Sb3Zn4 (forms γ and β) and Sb2Zn3 (forms η and ζ). Sb3Zn4 and Sb2Zn3 are both congruent melting compounds at 566 and 568 °C respectively with an eutectic transformation at 563 °C:Sb2Zn3(ζ) is formed at 407 °C starting from Sb3Zn4(β) and zinc. The decomposition, by cooling, occurs around 360 °C. 相似文献
liquid(43% Zn) ↔ Sb3Zn4(γ) + Sb2Zn3(η).