974 resultados para SUPRAMOLECULAR SOFT MATERIALS
                                
Resumo:
Two factors generally reported to influence bone density are body composition and muscle strength. However, it is unclear if these relationships are consistent across race and sex, especially in older persons. If differences do exist by race and/or sex, then strategies to maintain bone mass or minimize bone loss in older adults may need to be modified accordingly. Therefore, we examined the independent effects of bone mineral-free lean mass (LM), fat mass (FM), and muscle strength on regional and whole body bone mineral density (BMD) in a cohort of 2619 well-functioning older adults participating in the Health, Aging, and Body Composition (Health ABC) Study with complete measures. Participants included 738 white women, 599 black women, 827 white men, and 455 black men aged 70-79 years. BMD (g/cm(2)) of the femoral neck, whole body, upper and lower limb, and whole body and upper limb bone mineral-free LM and FM was assessed by dual-energy X-ray absorptiometry (DXA). Handgrip strength and knee extensor torque were determined by dynamometry. In analyses stratified by race and sex and adjusted for a number of confounders, LM was a significant (p < 0.001) determinant of BMD, except in white women for the lower limb and whole body. In women, FM also was an independent contributor to BMD at the femoral neck, and both PM and muscle strength contributed to limb BMD. The following were the respective Beta-weights (regression coefficients for standardized data, Std beta) and percent difference in BMD per unit (7.5 kg) LM: femoral neck, 0.202-0.386 and 4.7-6.9 %; lower limb,.0.209-0.357 and 2.9-3.5%; whole body, 0.239-0.484 and 3.0-4.7 %; and upper limb (unit = 0.5 kg), 0.231-0.407 and 3.1-3.4%. Adjusting for bone size (bone mineral apparent density [BMAD]) or body size BMD/height) diminished the importance of LM, and the contributory effect of FM became more pronounced. These results indicate that LM and FM were associated with bone mineral depending on the bone site and bone index used. Where differences did occur, they were primarily by sex not race. To preserve BMD, maintaining or increasing LM in the elderly would appear to be an appropriate strategy, regardless of race or sex.
                                
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We derive a general thermo-mechanical theory for particulate materials consisting of granules of arbitrary whose material points possess three translational and three independent rotational degrees of freedom. Additional field variables are the translational and rotational granular temperatures, the kinetic energies shape and size. The kinematics of granulate is described within the framework of a polar continuum theory of the velocity and spin fluctuations respectively and the usual thermodynamic temperature. We distinguish between averages over particle categories (averages in mass/velocity and moment of inertia/spin space, respectively) and particle phases where the average extends over distinct subsets of particle categories (multi phase flows). The relationship between the thermal energy in the granular system and phonon energy in a molecular system is briefly discussed in the main body of the paper and discussed in detail in the Appendix A. (C) 2001 Elsevier Science B.V. All rights reserved.
                                
                                
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This paper addresses the broader unresolved issues posed by the patenting of genetic materials that are central to dealing with the tension between the patenting and competition schemes, namely distinguishing between what has already been 'discovered' and economically useful innovations (including the thresholds for novelty and non-obviousness), the exclusion of some subject matter from patenting and the restrictions on access to genetic resources to facilitate further innovation. The possible solutions of raising the threshold patenting standards, taking advantage of international intellectual property law developments and compulsory licensing are examined as ways to ameliorate the possibly detrimental consequences of current genetic material patenting practices. (C) 2003 Elsevier B.V. All rights reserved.
                                
Resumo:
Managing financial institutions in an underdeveloped economic context has become a real challenge nowadays. In order to reach the organization`s planned goals, they have to deal with structural, behavioral and informational problems. From the systemic point of view, this situation gets even worse when the company does not present organizational boundaries and a cohesive identification for their stakeholders. Thus, European countries have some special financial lines in order to help the development of micro credit in Latin communities in an attempt to help the local economy. However, institutions like Caixa dos Andes in Peru present management problems when dealing with this complexity. Based on this, how can the systemic eye help in the diagnosis of soft problems of a Peruvian financial company? This study aims to diagnose soft problems of a Peruvian financial company based on soft variables like identity, communication and autonomy and also intends to identify possible ways to redesign its basic framework. The (VSM--Viable System Model) method from Beer (1967), applied in this diagnostic study, was used in a practical way as a management tool for organizations` analysis and planning. By describing the VSM`s five systems, the creation of a systemic vision or a total vision is possible, showing the organization`s complexity from the inside. Some company`s soft problems like double control, inefficient use of physical and human resources, low information flows, slowness, etc. The VSM presented an organizational diagnosis indicating effective solutions that do integrate its five systems.
                                
                                
Resumo:
The fabrication of heavy-duty printer heads involves a great deal of grinding work. Previously in the printer manufacturing industry, four grinding procedures were manually conducted in four grinding machines, respectively. The productivity of the whole grinding process was low due to the long loading time. Also, the machine floor space occupation was large because of the four separate grinding machines. The manual operation also caused inconsistent quality. This paper reports the system and process development of a highly integrated and automated high-speed grinding system for printer heads. The developed system, which is believed to be the first of its kind, not only produces printer heads of consistently good quality, but also significantly reduces the cycle time and machine floor space occupation.
                                
Resumo:
In this work, we report the synthesis, characterization and catalytic properties of a vanadium oxide-silicon oxide composite xerogel prepared by a soft chemistry approach. In order to obtain such material, we submitted a vanadium pentoxide gel previously synthesized via protonation of metavanadate species to an ""in situ"" progressive polycondensation into silica gel. The material has been characterized by X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. Further, the catalytic activity of this material was evaluated for the epoxidation of styrene and cyclooctene using iodosylbenzene, hydrogen peroxide and m-chloroperbenzoic acid as the oxidizing agent.
                                
Resumo:
Self-assembled materials consisting of V(2)O(5), polyallylamine (PAR) and silver nanoparticles (AgNPs) were obtained by the layer-by-layer (LbL) method, aiming at their application as electrodes for lithium-ion batteries and electrochromic devices. The method employed herein allowed for linear growth of visually homogeneous films composed of V(2)O(5), V(2)O(5)/PAH, and V(2)O(5)/PAH/AgNP with 15 bilayers. According to the Fourier transform infrared spectra, interaction between the oxygen atom of the vanadyl group and the amino group should be responsible for the growth of these films. This interaction also enabled establishment of an electrostatic shield between the lithium ions and the sites with higher negative charge, thereby raising the ionic mobility and consequently increasing the energy storage capacity and reducing the response time. According to the site-saturation model and the electrochemical and spectroelectrochemical results, the presence of PAH in the self-assembled host matrix decreased the number of V(2)O(5) electroactive sites. Thus, AgNPs were stabilized in PAR and inserted into the nanoarchitecture, so as to enhance the specific capacity. This should provide new conducting pathways and connect isolated V(2)O(5) particles in the host matrix. Therefore, new nanoarchitectures for specific interactions were formed spontaneously and chosen as examples in this work, aiming to demonstrate the potentiality of the adopted self-assembled method for enhancing the charge transport rate into the host matrices. The obtained materials displayed suitable properties for use as electrodes in lithium batteries and electrochromic devices.
                                
                                
Resumo:
Nanocomposite materials have received considerable attention in recent years due to their novel properties. Grain boundaries are considered to play an important role in nanostructured materials. This work focuses on the finite element analysis of the effect of grain boundaries on the overall mechanical properties of aluminium/alumina composites. A grain boundary is incorporated into the commonly used unit cell model to investigate its effect on material properties. By combining the unit cell model with an indentation model, coupled with experimental indentation measurements, the ''effective'' plastic property of the grain boundary is estimated. In addition, the strengthening mechanism is also discussed based on the Estrin-Mecking model.
                                
Resumo:
Introduction: Number 3 cleft or oral-nasal-ocular cleft is a well-known entity that was described by Morian over a century ago. This malformation is a paranasal-medial orbitomaxillary cleft running across the lacrimal segment of the lower eyelid and over the lacrimal groove. The Tessier number 3 naso-ocular cleft represents one of the most difficult and challenging malformations to correct for the reconstructive surgeon. We have conducted a retrospective analysis of our series consisting of 21 cases. Objective: The objective was to review the functional outcome and aesthetic results of the different techniques applied for each case. Materials and Methods: From 1997 to 2007, 21 patients with a Tessier number 3 cleft were treated in our craniofacial units. The clinical findings, tomographic studies, and surgical procedures were reviewed and analyzed. We have discussed our protocol of the treatment. Results: We have treated facial malformation in 2 craniofacial centers. Fourteen patients were evaluated in the first year of their life, with an average age at presentation of 3 years. Twelve patients were female, and 9 were male; 6 patients had amniotic bands in limbs, 5 patients had an association with Tessier number 11 cleft, 3 patients with number 9 cleft, and 1 with number 7 cleft. Related to cleft lip, 10 patients had bilateral cleft lip, and 8 patients had unilateral cleft lip. Three patients did not have any involvement of the upper lip. The alar base was deviated upward in 19 patients, 11 cases had severe anatomic alteration with the lateral border of the ala above the medial canthus, and 8 cases had a mild dislocation. Nine cases of lacrimal duct obstruction and 8 cases of lacrimal duct extrophy were identified. Twelve patients had a lower eyelid coloboma of varying grades, and there were 2 cases of microblepharia. Aiming the soft tissue reconstruction, eyelid, nose, and upper lip were evaluated regarding their position, absence of tissue, and position of medial canthus and ala. Twelve of our patients underwent correction in the same moment, their medial canthus rotated upward and the ala downward, using the contralateral side as the reference. The lip was treated using a Millard-like technique. Neo-conjunctivorhinostomy was performed in the same moment in 2 patients or later in 1 case. Four patients had plagiocephaly due to the cranial involvement, and they were submitted to cranioplasty. Three had neurosurgical approach and advancement of the frontal bandeau. One adult patient received an acrylic plate to reshape the frontal area. Conclusions: Tessier number 3 cleft is one of the most difficult and challenging malformations to correct for the reconstructive surgeon. Besides the difficulties of its treatment, patients with Tessier number 3 cleft may achieve good results when the team has good skills.
                                
Resumo:
The search for an ideal filler for soft tissue augmentation still continues. Because aging changes are continuous, temporary fillers should be preferred against permanent ones. Since 1999, the poly-L-lactic acid filler (PLA) has been marketed in Europe as Newfill. As a synthetic biocompatible polymer, PLA originally was used in suture materials and screws. In 2004, the U.S. Food and Drug Administration approved PLA under the name of Sculptra for the treatment of human immunodeficiency virus-related facial lipoatrophy. This study aimed to evaluate a 3-year follow-up investigation into the effect of PLA implant injection for the treatment of sunken nasolabial folds. Between October 2003 and February 2004, 10 women with a median age of 54 years (range, 43-60 years) were injected with polylactic acid hydrogel (Newfill) in the nasolabial fold area for aesthetic reasons. All the patients underwent three injections: one injection per month for 3 months. Evaluation of the results based on clinical examination and photography was performed at each session, at 6 months, and then 36 months after the third session. Injectable PLA was able to correct nasolabial folds successfully with a more lasting result than absorbable fillers commonly used in clinical practice, such as hyaluronic acid and collagen. Careful and standardized photographic documentation is indispensable.
                                
Resumo:
Smoothing the potential energy surface for structure optimization is a general and commonly applied strategy. We propose a combination of soft-core potential energy functions and a variation of the diffusion equation method to smooth potential energy surfaces, which is applicable to complex systems such as protein structures; The performance of the method was demonstrated by comparison with simulated annealing using the refinement of the undecapeptide Cyclosporin A as a test case. Simulations were repeated many times using different initial conditions and structures since the methods are heuristic and results are only meaningful in a statistical sense.
                                
 
                    