深海条件下固化剂对环氧树脂性能影响研究

利用深海模拟设备和力学测试设备考察了环氧树脂E51和Me-THPA、T403、593、H256 4种不同类型固化体系的吸水性能和弯曲性能,通过对比常压浸水处理和高静水压处理的环氧树脂性能变化,分析了深海条件下不同固化剂类型对环氧树脂性能影响.结果表明,在吸水性能方面,Me-THPA和T403固化剂高静水压处理试样吸水率低于常压浸水处理的试样,而固化剂593和H256与之相反；在力学性能方面,由于固化剂本身自由体积和极性基团的不同,不同固化剂在深海环境下强度下降不尽相同,Me-THPA和T403固化剂20 MPa高静水压处理试样相对于未处理试样弯曲性能有一定程度的降低,但强于常压浸水处理的试样,而593和H256固化剂在高静水压后弯曲性能弱于常压浸水处理的试样.     

Solid solubility of antilipemic agents and micronization of gemfibrozil in supercritical carbon dioxide

The solid solubilities of three antilipemic agents of clofibric acid, fenofibrate and gemfibrozil in supercritical carbon dioxide were measured using a semi-flow apparatus. The experimental data were taken at three isotherms of 308.2, 318.2 and 328.2 K, with pressure range from 10 to 22 MPa. These measured solid solubilities were correlated by the semi-empirical models of Mendez-Santiago-Teja and Chrastil. A solution model was also employed to fit the measured data. The absolute average deviation in solid solubility from semi-empirical models was 3-7%, and that from the solution model was 4-8%. The measured data satisfied the self-consistency test, and the optimally fitted parameters were reported.Gemfibrozil of the above antilipemic agents had high ranking among the best-selling generic drugs. It was then micronized using the rapid expansion of supercritical solution (RESS) method in this study. The particle size of gemfibrozil was micronized from its original 14.3 to 5.8 μm. It was also demonstrated that the dissolution rate of micronized gemfibrozil in a simulated intestinal fluid was enhanced by 5.5 times compared to that of the original compound.     

Antifoaming effect of chemical compounds in manure biogas reactors

A precise and efficient antifoaming control strategy in bioprocesses is a challenging task as foaming is a very complex phenomenon. Nevertheless, foam control is necessary, as foam is a major operational problem in biogas reactors. In the present study, the effect of 14 chemical compounds on foam reduction was evaluated at concentration of 0.05%, 0.1% and 0.5% v/v_sample, in raw and digested manure. Moreover, two antifoam injection methods were compared for foam reduction efficiency. Natural oils (rapeseed and sunflower oil), fatty acids (oleic, octanoic and derivative of natural fatty acids), siloxanes (polydimethylsiloxane) and ester (tributylphosphate) were found to be the most efficient compounds to suppress foam. The efficiency of antifoamers was dependant on their physicochemical properties and greatly correlated to their chemical characteristics for dissolving foam. The antifoamers were more efficient in reducing foam when added directly into the liquid phase rather than added in the headspace of the reactor.     

Design,Synthesis and Biological Evaluation of Highly Potent Simplified Archazolids

The archazolids are potent antiproliferative compounds that have recently emerged as a novel class of promising anticancer agents. Their complex macrolide structures and scarce natural supply make the development of more readily available analogues highly important. Herein, we report the design, synthesis and biological evaluation of four simplified and partially saturated archazolid derivatives. We also reveal important structure-activity relationship data as well as insights into the pharmacophore of these complex polyketides.     

Solvothermal synthesis and characterization of ytterbium/iron mixed oxide nanoparticles with potential functionalities for applications as multiplatform contrast agent in medical image techniques

A solvothermal route to prepare Glutathione capped hybrid ytterbium/iron oxide nanoparticles with potential applications as multiplatform contrast agent in medical image techniques has been developed. The influence of ytterbium/iron molar ratio used as precursor, as well as the degree of the autoclave filling on the structural and morphological characteristics of the obtained nanoparticles has been extensively studied. Although all nanoparticles present similar composition, with YbFeO₃ being the majority phase, size and morphology of the as synthetized nanoparticles are highly influenced by the critical temperature and by the over -saturation reached during the solvothermal process. We have demonstrated that glutathione properly functionalizes the hybrid nanoparticles, increasing their colloidal stability and decreasing their cytotoxicity. Additionally, they show good imaging in magnetic resonance and X-ray computerized tomography, thereby indicating promising potential as a dual contrast agent. This work presents, for the first time, glutathione functionalized ytterbium/iron oxide nanoparticles with potential applications in Biomedicine.     

Prevalence,Antimicrobial Resistance,and Virulence Characteristics of mecA‐Encoding Coagulase‐Negative Staphylococci Isolated from Soft Cheese in Brazil

Coagulase‐negative staphylococci (CoNS), which are generally neglected as foodborne bacteria, are emerging as significant opportunistic pathogens that may be highly resistant to available antimicrobial drugs. In this study, antimicrobial susceptibility patterns, mecA gene occurrence, and virulence‐associated characteristics were evaluated in CoNS isolated from soft cheese in Brazil. A total of 227 bacterial isolates were recovered from 35 cheese samples belonging to 5 batches with 7 different trademarks. The CoNS counts ranged from 10⁶ to 10⁷ CFU/g. High antimicrobial resistance percentages were observed for oxacillin (76.2%), penicillin (78.5%), erythromycin (67.8%), gentamicin (47.2%), clindamycin (35.7%), rifampicin (26.8%), azithromycin (14.7%), tetracycline (14.7%), levofloxacin (14.2%), and sulfamethoxazole‐trimethoprim (11.9%). A low antimicrobial resistance percentage was observed for chloramphenicol (2.3%), and all of the tested bacteria were susceptible to vancomycin and linezolid. In total, a multiple antibiotic resistance (MAR) index of >0.2 was observed for 80.6% of the isolated CoNS. However, the MAR index ranged from 50% to 92.6% when only bacterial cheese isolates belonging to the same trademark were considered. Regarding to the prevalence of CoNS carrying mecA gene, 81.5% of the isolated strains were mecA⁺, and 76.2% of these were phenotypically resistant to oxacillin. Three isolates carried the enterotoxin A gene (sea), 29.5% produced biofilm in a laboratory test, and α‐ or ß‐hemolysis were observed for 3% and 5.2%, respectively. This study highlights the extent of the antimicrobial resistance phenomenon in neglected foodborne microorganisms and the potential public health risks that are related to the consumption of CoNS‐contaminated soft cheese.     

Monocyclic Quinone Structure-Activity Patterns: Synthesis of Catalytic Inhibitors of Topoisomerase II with Potent Antiproliferative Activity

The monocyclic 1,4-benzoquinone, HU-331, the direct oxidation product of cannabidiol, inhibits the catalytic activity of topoisomerase II but without inducing DNA strand breaks or generating free radicals, and unlike many fused-ring quinones exhibits minimal cardiotoxicity. Thus, monocyclic quinones have potential as anticancer agents, and investigation of the structural origins of their biological activity is warranted. New syntheses of cannabidiol and (±)-HU-331 are here reported. Integrated synthetic protocols afforded a wide range of polysubstituted resorcinol derivatives; many of the corresponding novel 2-hydroxy-1,4-benzoquinone derivatives are potent inhibitors of the catalytic activity of topoisomerase II, some more so than HU-331, whose monoterpene unit replaced by a 3-cycloalkyl unit conferred increased antiproliferative properties in cell lines with IC₅₀ values extending below 1 mM, and greater stability in solution than HU-331. The principal pharmacophore of quinones related to HU-331 was identified. Selected monocyclic quinones show potential for the development of new anticancer agents.     

The use of statistical experimental design procedures in the development and “robust” manufacture of a water-based, corrosion-inhibiting adhesive primer

Details of the statistical experimental design techniques used to prepare a robust, water-based, corrosion-inhibiting, adhesive primer of low toxicity are given and the results are used to illustrate the efficacy of the approach to both manufacture and performance of the end product.     

The value of communicative skills for developing an energy strategy

A case study is presented of how a public-sector client organization engaged with a political directive on energy efficiency in buildings. The value of communication skills of built environment professionals is explored during a strategic change process. An interpretative approach is used to study the organizational discussions and interactions between mainly a senior engineer (an energy expert), the management team and officials. It demonstrates how the political directive led to an initially ambiguous energy target, but was successfully framed, contextualized and anchored within the organization. This change process was shaped by key actors’ ability to influence others. Use of discursive competence is important for explaining what stakeholders may gain from the changes needed to meet the energy target. The focus on the role of a senior engineer (middle management rather than top management) provides a novel perspective on how strategies develop and are adopted in organizations.