Antibacterial Polysiloxane Polymers and Coatings for Cochlear Implants

Within this study, new materials were synthesized and characterized based on polysiloxane modified with different ratios of N-acetyl-l-cysteine (NAC) and crosslinked via UV-assisted thiol-ene addition, in order to obtain efficient membranes able to resist bacterial adherence and biofilm formation. These membranes were subjected to in vitro testing for microbial adherence against S. pneumoniae using standardized tests. WISTAR rats were implanted for 4 weeks with crosslinked siloxane samples without and with NAC. A set of physical characterization methods was employed to assess the chemical structure and morphological aspects of the new synthetized materials before and after contact with the microbiological medium.     

Preliminary evidence that both blue and red light can induce alertness at night

Background  

A variety of studies have demonstrated that retinal light exposure can increase alertness at night. It is now well accepted that the circadian system is maximally sensitive to short-wavelength (blue) light and is quite insensitive to long-wavelength (red) light. Retinal exposures to blue light at night have been recently shown to impact alertness, implicating participation by the circadian system. The present experiment was conducted to look at the impact of both blue and red light at two different levels on nocturnal alertness. Visually effective but moderate levels of red light are ineffective for stimulating the circadian system. If it were shown that a moderate level of red light impacts alertness, it would have had to occur via a pathway other than through the circadian system.     

Comparison of catalytic properties of free and immobilized cellobiase Novozym 188

The enzyme cellobiase from Novo was immobilized in controlled pore silica particles by covalent binding with the silane-glutaraldehyde method with protein and activity yields of 67 and 13.7%, respectively. The activity of the free enzyme (FE) and immobilized enzyme (IE) was determined with 2 g/L of cellobiose, from 40 to 75°C at pH 3.0–7.0 for FE and from 40 to 70°C at pH 2.2–7.0 for IE. At pH 4.8 the maximum specific activity for the FE and IE occurred at 65°C: 17.8 and 2.2 micromol of glucose/(min·mg of protein), respectively. For all temperatures the optimum pH observed for FE was 4.5 whereas for IE it was shifted to 3.5. The energy of activation was 11 kcal/mol for FE and 5 kcal/mol for IE at pH 4.5–5, showing apparent diffusional limitation for the latter. Thermal stability of the FE and IE was determined with 2 g/L of cellobiose (pH 4.8) at temperatures from 40 to 70°C for FE and 40 to 75°C for IE. Free cellobiase maintained its activity practically constant for 240 min at temperatures up to 55°C. The IE has shown higher stability, retaining its activity in the sametest up to 60°C. Half-life experimental results for FE were 14.1, 2.1, and 0.17 h at 60, 65, and 70°C, respectively, whereas IE at the same temperatures had half-lives of 245, 21.3, and 2.9 h. The energy of thermal deactivation was 80.6 k cal/mol for the free enzyme and 85.2 k cal/mol for the IE, suggesting stabilization by immobilization.     

The contributions regarding the conception,designing, modelling and the implementation in a flexible cell of fabrication of a modular serial robot

The authors of the presented paper are propose to relief the calculus, modelling and construction of the translation module of an industrial robot which possess in his cinematic chain five degrees of freedom, type TTRTR. It is propose a choosing variant of the direct current driving engine of the translation module, knowing the output momentum and calculating the input momentum. This is realized by equalize of an equation which results from dynamic modeling of the robot with a designing equation which keep in view the component elements of the structure of the module. The robot is composed by: module of translation on horizontal to the base of the robot (MTB-Sil), module of translation on vertical (MTV-Sil), module of rotation round the vertical axis from the robot's arm, module of translation from the structure of the robot's arm (MT-Sil) and module of orientation assembled with clamping device. In the paper, also is presented an economic study regarding the implementation of the analyzed robot in a manufactural cell concerning the manufacturing and assembling of some types of car radiators. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

S,S‐Chiral Linker Induced U Shape with a Syn‐facial Sensitizer and Photocleavable Ethene Group

There is a major need for light‐activated materials for the release of sensitizers and drugs. Considering the success of chiral columns for the separation of enantiomer drugs, we synthesized an S,S‐chiral linker system covalently attached to silica with a sensitizer ethene near the silica surface. First, the silica surface was modified to be aromatic rich, by replacing 70% of the surface groups with (3‐phenoxypropyl)silane. We then synthesized a 3‐component conjugate [chlorin sensitizer, S,S‐chiral cyclohexane and ethene building blocks] in 5 steps with a 13% yield, and covalently bound the conjugate to the (3‐phenoxypropyl)silane‐coated silica surface. We hypothesized that the chiral linker would increase exposure of the ethene site for enhanced ¹O₂‐based sensitizer release. However, the chiral linker caused the sensitizer conjugate to adopt a U shape due to favored 1,2‐diaxial substituent orientation; resulting in a reduced efficiency of surface loading. Further accentuating the U shape was π–π stacking between the (3‐phenoxypropyl)silane and sensitizer. Semiempirical calculations and singlet oxygen luminescence data provided deeper insight into the sensitizer's orientation and release. This study has lead to insight on modifications of surfaces for drug photorelease and can help lead to the development of miniaturized photodynamic devices.     

Spasmolytic and antidiarrheal activities of Lippia thymoides (Verbenaceae) essential oil

Lippia thymoides (‘alecrim-do-mato’ or ‘alecrim-do-campo’) is used in Brazilian folk medicine to treat various illnesses, including diarrhea. This work aimed to evaluate in vitro spasmolytic and in vivo antidiarrheal activities of the L. thymoides essential oil (OOS) and to correlate with the traditional use of this plant. In isolated guinea-pig ileum, OOS presented a concentration-dependent spasmolytic activity in preparations pre-contracted with KCl 40 mM [EC₅₀ = 16.89 (11.56–24.66) μg/mL], and antagonized phasic contractions induced by 1 μM carbachol [IC₅₀ = 42.71 (37.35–48.83) μg/mL] or histamine [IC₅₀ = 32.38 (27.44–38.20) μg/mL]. In mice, OOS at 400 mg/kg reduced intestinal transit, at 200 and 400 mg/kg reduced total stool mass and at 400 mg/kg reduced intestinal fluid accumulation. It was shown that the antidiarrheal effect of OOS is related to the inhibition of smooth muscle contraction and may be due to the presence of major compound β-caryophyllene in this essential oil.     

Is the ‘canine surrogacy approach’ (CSA) still valid for dogs and humans in market-oriented and subsistence-oriented communities in Brazil?

Based on the assumptions that human food is available for dogs and isotope diet–tissue differences are similar in dogs and humans, the ‘canine surrogacy approach’ (CSA) has been used to infer patterns of ancient populations. The goal of this study was to test the CSA in urban (Brasília and Piracicaba) and in rural (Ubatuba and Maraã) areas. The hair C and N isotope ratios of modern dogs were compared with those of human fingernails from different regions of Brazil. Our CSA results showed a correlation between dog and human isotopes values: in rural areas δ¹⁵N of humans and dogs was not statistically different; contrarily, in urban centres, δ¹⁵N of humans was approximately 1?‰ higher (p?<?0.01) than δ¹⁵N of dogs; humans had lower δ¹³C values (p?<?0.01) than dogs in Brasília, Piracicaba and Ubatuba. In Maraã, there was not any significant difference between dogs and humans. We concluded that CSA is still valid as a first approach in modern societies. However, isotopic differences found suggest that in modern societies processed dog food is increasingly disconnecting human and dog, jeopardising the use of CSA in the future if the trend of increasing processed dog food consumption continues to occur.     

Aspects Regarding the Conception,Modeling and Implementation of an Articulated Robot in Space with Noises and Vibrations

The authors want to conceive and to model a structure of a 6R serial modular industrial robot with six freedom degrees. Some specific points are followed: the direct geometric modelling of the robot using the matrix of rotation method, the given in 3D modelling of the robot, the presentation of its components having some possible applications in the processes of production in the spaces with noises and vibrations. The direct geometrical modelling will be determinate the relative orientation matrices, which express the position of each system T_i, (i=1-6), according to the system T_i–1, also expressing the vectors of relative position of origin O_i of the systems T_i. They will be expressed the orientation of each system T_i in account to the fixed system T_o attached to the robot base, the set of independent parameters of orientation then are obtained the final equation of the column vector of the generalized coordinates, which express the position and the orientation of the clamping device. The paper presents the two possible applications of the studied robot implementation in a flexible manufacturing cel for the manipulation operations of parts. The robot will be used on the other side for the execution of weld in a points applied to the car carcases. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Determination of the addendum modification at helical gears,at the points where the meshing starts and ends,based on the relative velocity equalization criterion

The paper gives a new method for the determination of the specific addendum modifications at helical gears. The method is based on the equalization of the relative velocities at the points where the meshing of the teeth begins and ends. The numerical values were obtained for some given gears using MathCAD. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)