Cellulose pyrolysis and quantum chemistry

Cellulose is the major constituent of most plants of interest as renewable sources of energy and is the most extensively studied form of biomass or biomass constituent. Predicting the mass loss and product yields when cellulose is subjected to increased temperature represents a fundamental problem in the thermal release of biomass energy. Unfortunately, at this time, there is no internally consistent model of cellulose pyrolysis that can organize the varied experimental data now available or provide a guide for additional experiments. Here, we present a model of direct cellulose pyrolysis using a multistage decay scheme that we first presented in the IJQC in 1984. This decay scheme can, with the help of an inverse method of assigning reaction rates, provide a reasonable account of the direct fast pyrolysis yield measurements. The model is suggestive of dissociation states of d-glucose (C6H10O5,), the fundamental cellulose monomer. The model raises the question as to whether quantum chemistry could now provide the dissociation energies for the principal breakup modes of glucose into C-1, C-2, C-3, C-4, and C-5 compounds. These calculations would help in achieving a more fundamental description of volatile generation from cellulose pyrolysis and could serve as a guide for treating hemicellulose and lignin, the other major biomass constituents. Such advances could lead to the development of a predictive science of biomass pyrolysis that would facilitate the design of liquifiers and gasifiers based upon renewable feedstocks. (C) 1998 John Wiley & Sons, Inc.

Thermo-analyses of polyaniline and its derivatives

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Hearing loss in patients with diabetes mellitus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lung ultrasound in acute respiratory distress syndrome and acute lung injury

Purpose of reviewLung ultrasound at the bedside can provide accurate information on lung status in critically ill patients with acute respiratory distress syndrome.Recent findingsLung ultrasound can replace bedside chest radiography and lung computed tomography for assessment of pleural effusion, pneumothorax, alveolar- interstitial syndrome, lung consolidation, pulmonary abscess and lung recruitment/de-recruitment. It can also accurately determine the type of lung morphology at the bedside (focal or diffuse aeration loss), and therefore it is useful for optimizing positive end-expiratory pressure. The learning curve is brief, so most intensive care physicians will be able to use it after a few weeks of training.SummaryLung ultrasound is noninvasive, easily repeatable and allows assessment of changes in lung aeration induced by the various therapies. It is among the most promising bedside techniques for monitoring patients with acute respiratory distress syndrome.

Administration of physiologic levels of triiodothyronine increases leptin expression in calorie-restricted obese rats, but does not influence weight loss

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Loss of vision secondary to obsessive-compulsive disorder: a case report

Objective: To report a rare case of self-inflicted eye injury secondary to obsessive-compulsive disorder (OCD).Method: Case report.Results: A 41 year-old patient had significant bilateral visual loss and blunt trauma through touching his ocular cavities due to recurrent doubts regarding their shape and urges to check the format of bones and cartilages. Differential diagnosis with tic disorders is discussed, and the patient's treatment approach is described.Conclusion: Although rare, severe clinical complications can occur in OCD. (C) 2009 Elsevier B.V. All rights reserved.

Incidence and physical properties of PSE chicken meat in a commercial processing plant

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chicken meat quality as a function of fasting period and water spray

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of body weight loss on serum progesterone concentrations of non-lactating dairy cows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Use of prebiotics and probiotics of bacterial and yeast origin for free-range broiler chickens

This study aimed to evaluate the effects of probiotics and prebiotics of bacterial and yeast origin on the performance, development of the digestive system, carcass yield and meat quality of free-range broiler chickens. Five hundred and sixty male chicks of the strain ISA S757-N were reared from one to 84 days old. The birds were distributed in four treatments according to a completely randomized block design: T1 = Control, T2 = Probiotics and Prebiotics of bacterial origin, T3 = Probiotics and prebiotics of yeast origin, T4 = Probiotics and prebiotics of bacterial origin + probiotics and prebiotics of yeast origin. There were four repetitions with 35 birds per repetition, and the birds had access to a pasture area after 35 days of age. Characteristics evaluated were performance, development of the digestive system, carcass and parts yield, abdominal fat, breast meat physical measurements (length, width and height) and meat quality parameters (pH from breast and leg meat, cooking loss and shearing force from breast meat). Lower mortality (p<0.05) and higher weight gain from 64 to 77 and 64 to 84 days of age were seen in birds supplemented with probiotics and prebiotics of bacterial origin compared to the non-supplemented birds (control). There were significant differences (p<0.05) among treatments for carcass yield. Birds supplemented with both probiotics and prebiotics of microbial and yeast origin (T4) showed higher carcass yield than control birds. Supplementation with probiotics and prebiotics of bacterial origin (T2) or the supplementation of these together with those of yeast origin (T4) reduced mortality and increased the carcass yield in free-range broiler chickens.

The influence of chronic stress imposed on pregnant rats on the induced bone loss in their adult offspring

Background and objective: Stress during pregnancy may alter offspring susceptibility to diseases during adulthood. In the present study, female Lewis rats were subjected to chronic stress during the gestational period, and the effect of this stress was evaluated histometrically on the progression of ligature-induced bone loss in their adult offspring.Material and methods: After confirming pregnancy, half of the pregnant rats were randomly designated as control animals (no stress regimen was imposed), and the other half was submitted to a chronic stress model (immobilization at cold temperature) between the 7th and the 18th gestational day. After birth, 12 male rats delivered by stressed mothers - Group 1 (G1) - and 12 male rats delivered by non-stressed mothers - Group 2 (G2) - were selected. When birthed rats reached 250 g of body weight, a silk ligature was placed around their maxillary right second molar in order to induce bone loss. The non-ligated left side served as a control. Sixty days later, these animals were sacrificed by anaesthetic overdose. After routine laboratorial processing, images of the histological sections were digitized and submitted for histometric measurement using two parameters: histological attachment loss and bone loss.Results: on the ligated side, G1 presented with greater histological attachment and bone loss than G2 (p < 0.05). on the non-ligated control side, neither of the groups presented with alterations in these parameters (p > 0.05).Conclusion: The chronic stress regimen imposed on pregnant rats produced a greater progression of ligature-induced bone loss in their adult offspring. (C) 0 2011 Elsevier Ltd. All rights reserved.

pH-cycling models for in vitro evaluation of the efficacy of fluoridated dentifrices for caries control: strengths and limitations

Despite a plethora of in situ studies and clinical trials evaluating the efficacy of fluoridated dentifrices on caries control, in vitro pH cycling models are still broadly used because they mimic the dynamics of mineral loss and gain involved in caries formation. This paper critically reviews the current literature on existing pH-cycling models for the in vitro evaluation of the efficacy of fluoridated dentifrices for caries control, focusing on their strengths and limitations. A search was undertaken in the MEDLINE electronic journal database using the keywords "pH-cycling", "demineralization", "remineralization", "in vitro", "fluoride", "dentifrice". The primary outcome was the decrease of demineralization or the increase of remineralization as measured by different methods (e. g.: transverse microradiography) or tooth fluoride uptake. Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. One hundred and sixteen studies were included, of which 42 addressed specifically the comparison of dentifrices using different pH-cycling models. The other studies included meta-analysis or reviews, data about the effect of different fluoride sources on de-remineralization, different methods for analysis de-remineralization and chemical variables and characteristics of dental hard tissues that might have influence on de-remineralization processes. Generally, the studies presented ability to detect known results established by clinical trials, to demonstrate dose-related responses in the fluoride content of the dentifrices, and to provide repeatability and reproducibility between tests. In order to accomplish these features satisfactorily, it is mandatory to take into account the type of substrate and baseline artificial lesion, as well as the adequate response variables and statistical approaches to be used. This critical review of literature showed that the currently available pH-cycling models are appropriate to detect dose-response and pH-response of fluoride dentifrices, and to evaluate the impact of new active principles on the effect of fluoridated dentifrices, as well as their association with other anti-caries treatments.

Tumor Necrosis Factor alpha and Interleukin-1 beta Modulate Calcium and Nitric Oxide Signaling in Mechanically Stimulated Osteocytes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Short-term induction of thrombocytopenia delays periodontal healing in rats with periodontal disease: participation of endostatin and vascular endothelial growth factor

Background and Objective:Platelets contain factors, including VEGF and endostatin, that can modulate the healing process. We evaluated the effects of severe thrombocytopenia on periodontal healing in rats and determined the contribution of VEGF and endostatin to the healing process.Material and Methods:Rats were distributed into three test groups and two control groups. Cotton ligatures were placed at the gingival margin level of the lower first molar in the test groups. Sham-operated rats and rats in one of the periodontitis groups were killed 15 days later. Rats in the remaining two periodontitis groups had the ligatures removed in order to study the spontaneous recovery from the periodontal disease 15 days later, and these rats were treated with rabbit antiplatelet serum, in order to induce thrombocytopenia, or normal rabbit serum. An additional group without ligatures received antiplatet serum in the same period.Results:After ligature removal, rats treated with normal rabbit serum showed reduced myeloperoxidase activity, decreased alveolar bone loss and increased numbers of blood vessels. Thrombocytopenia caused a delay in alveolar bone regeneration, a decrease in the number of vessels and a modest decrease in myeloperoxidase activity. In the rats with periodontitis, serum endostatin concentrations were slightly decreased and serum VEGF remained unchanged compared with sham-operated animals. After ligature removal, a significant VEGF increase and endostatin decrease were observed in the rats treated with normal rabbit serum. Thrombocytopenia led to a dramatic fall in both VEGF and endostatin concentrations.Conclusion:Thrombocytopenia leads to a delay of periodontal healing in the situation of experimental periodontitis, which might be mediated in part by a decrease in the serum concentration of VEGF and endostatin derived from the platelets. However, other factors derived from the platelets may also have contributed to a delay of periodontal healing in the rats with thrombocytopenia.

Morphological evidences indicate that the interference of cimetidine on the peritubular components is responsible for detachment and apoptosis of Sertoli cells

Cimetidine, referred as antiandrogenic agent, has caused alterations in the seminiferous tubules, including alterations in the peritubular tissue and death of myoid cells by apoptosis. Regarding the structural and functional importance of the peritubular tissue for the maintenance of Sertoli cells (SC), we purpose to investigate the SC-basement membrane interface, focusing the morphological features of SC and their interaction with the basement membrane in the affected tubules by cimetidine. Ten animals were distributed into two groups, control (CG) and cimetidine (CmG) which received saline solution and 50 mg of cimetidine per kg of body weight, respectively, for 52 days. The testes were fixed, dehydrated and embedded for analyses under light and transmission electron microscopy. Paraffin sections were submitted to the TUNEL method; sections of testes embedded in glycol methacrylate were submitted to PAS method and stained by H&E for morphological and quantitative analyses of Sertoli Cells. In the CmG, the SC nuclei were positive to the TUNEL method and showed typical morphological alterations of cell death by apoptosis (from early to advanced stages). A significant reduction in the number of Sertoli Cells was probably due to death of these cells by apoptosis. A close relationship between SC nuclear alterations (including a high frequency of dislocated nuclei from the basal portion) and damage in the peritubular tissue was observed. The ultrastructural analysis showed a parallelism between the gradual advancement of apoptotic process in SC and detachment of the anchoring sites (hemidesmosomes) of SC plasma membrane from the lamina densa. The presence of portions of lamina densa underlying the detached hemidesmosomes indicates a continuous deposition of lamina densa, resulting in the thickening of the basal lamina. The results indicate a possible disarrangement of the SC cytoskeleton, including the focal adhesion structure. These alterations are related to SC apoptosis and probably result from disturbs induced by cimetidine on the peritubular tissue.