Morphology and supermolecular structure of polypropylene–poly(1-butene)–hydrogenated oligo(cyclopentadiene) ternary blends

Ternary blends containing polypropylene, poly(1-butene), and hydrogenated oligo(cyclopentadiene) have been studied using microscopic, calorimetric, and X-ray diffraction techniques. While no phase separation was found to occur in the melt for all the considered compositions, demixing phenomena were observed by scanning electron microscopy in the ternary blends after crystallization of both polyolefins. On the other hand, a homogeneous surface without the presence of separate domains was observed for blends quenched avoiding the crystallization of polypropylene. The composition has been found to affect the crystallization and the melting properties of the ternary blends and the crystal modification of polypropylene. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1878–1882, 1998     

Contribution of the cashew gum (Anacardium occidentale L.) for development of layer-by-layer films with potential application in nanobiomedical devices

The search for bioactive molecules to be employed as recognition elements in biosensors has stimulated researchers to pore over the rich Brazilian biodiversity. In this sense, we introduce the use of natural cashew gum (Anacardium occidentale L.) as an active biomaterial to be used in the form of layer-by-layer films, in conjunction with phthalocyanines, which were tested as electrochemical sensors for dopamine detection. We investigated the effects of chemical composition of cashew gum from two different regions of Brazil (Piauí and Ceará states) on the physico-chemical characteristics of these nanostructures. The morphology of the nanostructures containing cashew gum was studied by atomic force microscopy which indicates that smooth films punctuated by globular features were formed that showed low roughness values. The results indicate that, independent of the origin, cashew gum stands out as an excellent film forming material with potential application in nanobiomedical devices as electrochemical sensors.     

Chemical composition and antimicrobial activity of the essential oil of Lippia grandis Schauer (Verbenaceae) from the western Amazon

Lippia grandis Schauer is an aromatic plant that has been used as a spice in Brazilian culinary and in traditional medicine to treat liver disease, disorders of the stomach and throat infections. We determined the chemical composition of the essential oil of L. grandis and evaluated its potential for the treatment of clinically-important pathogenic micro-organisms. The essential oil was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), giving carvacrol (37.12%), ρ-cymene (11.64%), and thymol (7.83%) as the main components. The agar disk diffusion method of the essential oil was effective against 75% of the micro-organisms analyzed, in particular, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli. The minimum inhibitory concentration was 0.57 mg/ml for E. faecalis and 1.15 mg/ml for all the other strains. The results indicate that the essential oil of L. grandis contains chemical compounds with good potential for the treatment of infections.     

Synthetic peptides as substrate for assaying the proteolytic activity of Lactobacillus helveticus

Four Lactobacillus helveticus strains were studied for proteolytic capacity and general aminopeptidase (AP) and X-Pro dipeptidyl aminopeptidase (DAP) activity. The rate of hydrolysis and the activity against synthetic substrates with N-terminal residues of Arg, Lys, Leu, Glu or Pro, varied markedly among the strains. The X-Pro DAP activity was consistently high. The crude cell-wall and cytoplasm extracts from strain Lb. helveticus ISLC59 were analysed thoroughly for their proteolysis ability by using four synthetic peptide substrates, including alpha(s)1-CN(f1-23). Peptides formed during in vitro hydrolysis of the synthetic substrates by cell wall and cytoplasm preparations were identified by LC-ESI/MS. In doing so, it was possible to infer a prevalent endopeptidase activity splitting Lys7-His8 and Gln13-Glu14 bonds in the cytoplasm, and to deduce a secondary activity, which hydrolysed Glu14-Val15, Leu16-Asn17, Glu18-Asn19 and Lys3-His4 bonds lacking in the cell-wall. The presence of exopeptidases, as mainly AP, DAP, and carboxypeptidase (CPase) was deduced from the formation of several N- and C-terminally truncated peptides sets. The AP activity was higher in the cell-wall layer, where CPase activity was absent. The in vitro assays with cell extracts of the Lb. helveticus ISLC59 strain revealed extensive exopeptidase and endopeptidase activities. In several cases, the hydrolytic system of Lb. helveticus that splits in vitro alpha(s)1-CN(f1-23) peptide bonds was similar to that of Lactococcus lactis. The effects were also compared with those occurring in vivo in hard cheese such as Grana Padano.     

Home birth and short-stay delivery. Lessons in health care financing for providers of health care for women

The current restructuring of the U.S. health care delivery system is driven primarily by economic forces. Although primary care providers may understand the roles of technology and advocacy in fostering fundamental change, they may not be familiar with the issues related to financing of health care and, thus, may not fully appreciate the extent to which economic factors influence the character of their professional lives and the services they provide. Analysis of the loss of the home birth option in the 1950s provides a method for understanding and influencing the factors driving health care restructuring today. In examining short-stay delivery in the 1990s, this article also addresses ways in which managed health care systems may improve or restrict women's access to a variety of primary care services.     

Design,Synthesis, and Preliminary Biological Evaluation of Pyrrolo[3,4‐c]quinolin‐1‐one and Oxoisoindoline Derivatives as Aggrecanase Inhibitors

A small set of aggrecanase inhibitors based on the pyrrolo[3,4‐c]quinolin‐1‐one or oxoisoindoline frameworks bearing a 4‐(benzyloxy)phenyl substituent and different zinc binding groups were rationally designed and evaluated in silico by docking studies using the crystal structure of the ADAMTS‐5 catalytic domain (PDB code: 3B8Z). The designed compounds were synthesized via straightforward routes and tested for their potential inhibitory activity against ADAMTS‐5 and ADAMTS‐4. Among the compounds containing the pyrrolo[3,4‐c]quinolinone tricyclic system, hydroxamate derivative 2 b inhibited both ADAMTS‐5 and ADAMTS‐4, with IC₅₀ values in the submicromolar range and an inhibitory profile very similar to that of reference carboxylate derivative 11 . Conversely, the corresponding carboxylate derivative 2 a was significantly less active and unable to discriminate between ADAMTS‐5 and ‐4. The structure–activity relationship analysis of pyrroloquinolinone derivatives 2 a – i suggests that the carboxylate or hydroxamate groups of compounds 2 a , b play a key role in the interaction of these compounds with ADAMTS‐5 and ‐4. On the other hand, the oxoisoindoline derivatives 3 a , b lack significant ADAMTS‐4 inhibitory activity and inhibit ADAMTS‐5 showing IC₂₅ values in the micromolar range.     

Thermally induced chemical evolution in polyimide films investigated by X‐ray photoelectron spectroscopy

Thermally modified polyimide films based on 1,4‐Phenylene diamine (p‐PDA) and 3,3′,4,4′ – Benzophenone tetracarboxylic dianhydride (BTDA) were prepared and their chemical structure transformation after thermal treatment at 350 °C–500 °C was investigated. X‐ray diffraction results revealed an increase in the polymer chain order for all treated PI samples as a consequence of the thermal treatment and chain interaction. TGA analysis showed that the heat treatment promoted different thermal degradation profiles. Electron spin resonance evidenced a large population of free radicals as a result of homogeneous bond cleavage when the thermal treatment was performed at 500 °C. X‐ray photoelectron spectroscopy analysis indicated that the chemical structure transformation not only occurs on the outer surface but also in the sub‐surface layer. These results show that controlled fast thermal treatment can produce materials with specific characteristics and may serve as a general strategy for changing both structural and chemical properties of the polymers. POLYM. ENG. SCI., 58:943–951, 2018. © 2017 Society of Plastics Engineers     

Detection of helmets on motorcyclists

Multimedia Tools and Applications - The use of motorcycle accidents has rapidly increased. Although the helmet is the main safety equipment of motorcyclists, many drivers do not use it. This paper...     

Modeling and simulation of the anode in direct ethanol fuels cells

Mathematical modeling has been extensively applied to the study and development of fuel cells. In this work, the objective is to characterize a mechanistic model for the anode of a direct ethanol fuel cell and perform appropriate simulations.