Lower adiponectin is associated with higher anthropometry and insulin resistance but not with low cardiorespiratory fitness in adolescents.

PURPOSE: The aim of this study was to analyze the relationship between adiposity, cardiometabolic risk and cardiorespiratory fitness (CRF) according to different groups of adiponectin concentration. METHODS: 255 adolescents of both sexes, aged 11-17 years old, participated. Anthropometric and biochemical parameters such as body mass, height, abdominal circumference (AC), waist circumference (WC), fat mass, fat-free mass, total cholesterol (TC), high-density lipoprotein (HDL-c), low-density lipoprotein (LDL-c), triglycerides (TG), glucose, insulin, adiponectin, blood pressure, peak oxygen consumption (VO2peak) were measured. Body mass index (BMI), z-score BMI (BMI-z), triponderal mass index (TMI), waist-to-height ratio (WHtR), homeostasis model to assessment insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI) were calculated. Adiponectin was categorized: low adiponectin concentration (LAC ≤ 5.18 µg/mL-1), intermediate (IAC = 5.18 and 7.63 µg/mL-1) and high (HAC ≥ 7.63 µg/ml-1). RESULTS: LAC showed higher BMI, BMI-z and TMI than the other groups (p < 0.05) and higher AC, WC and WHtR that the HAC (p < 0.05). IAC showed lower values of TC, LDL-c and TG, and the LAC presented the highest values of insulin, HOMA-IR and QUICKI (p < 0.05) to the IAC and HAC. HAC presented the lower VO2peak than the other groups (p < 0.01). BMI, TMI, glucose, insulin, HOMA-IR showed inverse, and QUICKI a direct and weak correlation with adiponectin (p < 0.05). No significant association was found between adiponectin and VO2peak (p > 0.05). CONCLUSION: The LAC group had higher means in the anthropometric variables and the worst results related to insulin resistance and sensitivity. Thus, adiponectin may play an important role in obesity and reduced concentration may be a factor in the development of obesity-associated morbidities.

Responsiveness on metabolic syndrome criteria and hepatic parameters after 12 weeks and 24 weeks of multidisciplinary intervention in overweight adolescents.

PURPOSE: This study aimed to evaluate the effect and individual responsiveness after 12 (12wk) and 24 weeks (24wk) of physical exercise (PE) and nutritional guidance (NG) on metabolic syndrome (MetS) criteria and hepatic parameters in overweight adolescents. METHODS: The study comprised 94 overweight adolescents, aged between 10 and 16 years old, from both sexes, allocated into groups: PE and NG (PENGG, n = 64) and control with NG (NGCG, n = 30). Variables were collected at baseline, 12wk, and 24wk. Weight, height, abdominal circumference (AC), blood pressure, and peak oxygen consumption (VO2peak), as well as insulin, triglycerides (TAG), high-density lipoprotein (HDL-c), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were evaluated. HOMA-IR and QUICKI were calculated. PE session consisted of 45 min of indoor cycling, 45 min of walking, and 20 min of stretching, three times a week. The NG consisted of three collective sessions in the first 12wk. Anova, effect size, and prevalence of responders were used for statistical analysis. RESULTS: The PENGG12wk reduced anthropometric and metabolic measurements, while increased VO2peak and HDL-c. The PEG24wk promoted anthropometric, blood pressure, metabolic, and VO2peak improvements, but participants without PE returned to pre-exercise status and presented worsening AST and ALT concentrations. Frequencies of respondents in PENGG12wk versus (vs) NGCG12wk were, respectively, AC (69.1% vs 17.6%, p < 0.01), HDL-c (87.2% vs 23.5%, p < 0.01), TAG (67.3% vs 41.7%, p = 0.05) and ALT (45.5% vs 5,9%; p = 0.003). CONCLUSION: Interventions with PE were effective to reduce MetS components in 12wk and maintenance in 24wk, showing anthropometric, metabolic, and VO2peak improvements. Higher individual responses were observed in 12wk and in 24wk, important changes in overweight adolescent's therapy. LEVEL OF EVIDENCE: Level I, evidence obtained from well-designed controlled trials randomization. TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION: Brazilian Registry of Clinical Trials (RBR-4v6h7b) and date of registration April 4th, 2020.

Bending, buckling and torsional resistance of rotary and reciprocating glide path instruments.

AIM: To evaluate the bending, buckling and torsional resistance of ProGlider (PG) (Dentsply Sirona, Ballaigues, Switzerland), R-Pilot (RP) (VDW, Munich, Germany) and WaveOne Gold Glider (WOGG) (Dentsply Sirona). METHODOLOGY: Ninety instruments were used: 30 PG (size 0.16, .02v taper), 30 RP (size 0.125, .04 taper) and 30 WOGG (size 0.15, .02v taper). The bending resistance test was performed on 10 randomly selected instruments of each system according to ISO 3630-1 specifications. For the buckling resistance test, a loading was applied in the axial direction of each instrument using a universal test machine, with a 20 N cell and 15 mm min-1 speed, in the axial direction. When a lateral elastic displacement of 1 mm occurred, the force was registered. The torsional resistance test was performed according to ISO 3630-1 specifications. Statistical analysis was performed using one-way anova and post hoc Student-Newman-Keuls test (P < 0.05). RESULTS: WOGG had the lowest bending resistance, whilst RP had the highest bending resistance (P < 0.05). RP also had the highest buckling resistance, and WOGG had the lowest (P < 0.05). PG had intermediate results regarding bending and buckling resistance, with significant differences to RP and WOGG (P < 0.05). RP had the highest torsional strength and the lowest angular deflection when compared to PG and WOGG (P < 0.05). No differences in the torsional strength and angular deflection were observed between WOGG and PG (P> 0.05). CONCLUSION: The glide path instruments had different behaviours in term of bending, buckling and torsional resistance.

8-Hydroxyquinoline-5-sulfonamides are promising antifungal candidates for the topical treatment of dermatomycosis.

AIM: The purpose of this study was to uncover insights into the mechanism of action of the 8-hydroxyquinoline derivatives PH151 and PH153. In addition, with the future perspective of developing a topical drug for the treatment of candidiasis and dermatophytosis, the antifungal activity of a nanoemulsion formulation containing the most active compound (PH151) is also presented here. METHODS AND RESULTS: Sorbitol protection assay and scanning electron microscopy indicate that the 8-hydroxyquinoline derivatives act on the cell wall of Candida sp. and dermatophytes and they inhibit the pseudohyphae formation of C. albicans. These findings demonstrate a strong effect of these compounds on C. albicans morphogenesis, which can be considered a potential mode of action for this molecule. Besides, the nanoemulsion formulation MIC values ranged from 0·5 to 4 µg ml-1 demonstrating the significant antifungal activity when incorporated into a pharmaceutical formulation. CONCLUSIONS: Taken together, the results support the potential of these molecules as promising antifungal candidates for the treatment of candidiasis and dermatophytosis. SIGNIFICANCE AND IMPACT OF THE STUDY: There is an emerging need to fill the pipeline with new antifungal drugs due to the limitations presented by the currently used drugs. In this study, we have described a novel formulation with a 8-hydroxyquinoline-5-sulfonamide derivative which has presented a great potency in providing a finished product. Furthermore, the derivative has shown a selective mechanism of action confirming its potential to be developed into a new drug candidate.

Recording and erasure of photorefractive holograms in undoped BTO crystal at moderate to high intensities of 639.7 nm laser under action of 532 nm laser pre-illumination.

We investigate recording and erasure of photorefractive holographic gratings in an undoped Bi12TiO20 crystal in a moderate to high intensity regime of the recording beams at 639.7 nm without and with the action of laser pre-illumination at 532 nm. The detected hologram without pre-illumination indicates the participation of two photorefractive electronic gratings in its recording process, and the diffracted signal by itself exhibits a fivefold enhancement when the total intensity increases from 38.4 to 214.5 mW/cm2. The dependence of the measured total diffraction efficiency on intensity was investigated and showed linear behavior. At least three gratings are present in the regime of pre-illumination and participate in the writing and erasure of holographic mechanisms. Two of them are electronic, and one is hole-based, with a phase difference of Δϕ between them. The theoretical approach used to analyze the total diffraction efficiency based upon the photorefractivity standard model, and considering the presence of the three gratings, showed good agreement with the holographic erasure experimental data and permitted us to compute Δϕ, which exhibited strong and unusual dependence on the total intensity.

Assessing an imidazolium salt's performance as antifungal agent on a mouthwash formulation.

AIMS: This study demonstrates the development of a mouthwash formulation containing the imidazolium salt (IMS) 1-n-hexadecyl-3-methylimidazolium chloride (C16 MImCl), considering its stability and efficacy against Candida sp. Biofilm formation. METHODS AND RESULTS: A variety of in vitro test methods were applied, assessing contaminated acrylic resin strip specimens before and after applying the mouthwash formulations. The formulation using C16 MImCl presented a similar antibiofilm activity to cetylpyridinium chloride one and a commercial mouthwash, but at a 10 times lower concentration. Scanning electron microscopy imaging demonstrated that the selected mouthwash preparation fully destroys the biofilm cells, while with the hypoallergenicity test no irritant effect was observed in ex vivo model. CONCLUSIONS: The results presented herein indicate a high potential for imidazolium salts application as mouthwash agents that can eliminate Candida biofilm growth at very low concentrations. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates a new and effective antibiofilm formulation containing the IMS C16 MImCl. These findings suggest the IMS' use as mouthwash formulations active ingredient against Candida biofilms on oral surfaces, as it outperforms the often used cetylpyridinium chloride at a 10 times lower concentration.

Goats reinfected with toxoplasma gondii: loss of viable prolificacy and gross revenue / Cabras reinfectadas com toxoplasma gondii: perdas de prolificidade viável e receita bruta

We determined the reproductive parameters and clinical disorders in pregnant goats infected and reinfected with Toxoplasma gondii, and posteriorly the loss of gross revenue due to congenital toxoplasmosis was estimated. Of the 25 non-pregnant females negative for T. gondii, 20 were orally inoculated (ME 49 strain) and of these, 15 pregnant females chronically infected were orally reinoculated (VEG strain) with T. gondii oocysts. Five groups were formed (n=5): GI, GII and GIII (reinoculations at 40, 80 and 120 days of gestation, respectively), GIV (inoculation) and GV (no inoculation). Clinical and serological exams were performed on days 0 (prior to inoculation), 3, 6 9, 15 and 21 and every 7 days post-inoculation. Exams were also performed on day 3 and every 7 days post-reinoculation. Reproductive management was performed on all females and initiated when the females infected displayed IgG titers IFAT<1,024. From the average prolificacy indexes of each experimental group were estimated: total production of kilograms of live weight (total kg LW) of goats for slaughter, gross revenue and loss of gross revenue in U.S. dollars (US$), designed for a herd of 1,000 matrices. The unviable prolificacy indexes were 0.8 (GI), 1.2 (GII) and 0.2 (GIII). Clinical disorders affected 57.1% (GI), 75.0% (GII) and 16.7% (GIII) of the offspring of goats reinfected with T. gondii. Congenital toxoplasmosis in goats reinfected resulted in the loss of 26.5% of gross revenues, being GI (US$ 10,577.60 or 57.1%) and GII (US$ 12,693.12 or 60%) holders of the highest values and percentages of economic losses. It was found that congenital toxoplasmosis reinfection cause clinical disorders in goats chronically infected with T. gondii and their offspring with birth of unviable animals and loss of gross revenue, at different stages of pregnancy (40, 80 and 120 days of gestation)...

Nós determinamos os parâmetros reprodutivos e distúrbios clínicos em cabras gestantes infectadas e reinfectados com Toxoplasma gondii, e posteriormente, foi estimada a perda de receita bruta devido à toxoplasmose congênita. Das 25 fêmeas não prenhes negativas para T. gondii, 20 foram inoculadas oralmente (cepa ME 49) e, destas, 15 fêmeas gestantes infectadas cronicamente foram reinoculadas (cepa VEG), via oral, com oocistos de T. gondii. Cinco grupos foram formados (n = 5): GI, GII e GIII (reinoculações aos 40, 80 e 120 dias de gestação, respectivamente), GIV (inoculação) e GV (não inoculação). Exames clínicos e sorológicos foram realizados nos dias 0 (antes da inoculação), 3, 6 9, 15 e 21 e a cada sete dias após a inoculação. Os exames também foram realizados nos dias 3 e a cada sete dias de pós-reinoculação. Manejo reprodutivo foi realizado em todas as fêmeas e iniciou-se quando as fêmeas infectadas exibiram títulos de anticorpos IgG<1.024. A partir dos índices médios de prolificidade de cada grupo experimental foram estimados: a produção total de kg de peso vivo (total kg PV) de cabritos para o abate, receita bruta e perda de receita bruta em dólares norte-americanos (US$), projetadas para um rebanho de 1000 matrizes. Os índices de prolificidade inviáveis foram de 0,8 (GI), 1.2 (GII) e 0,2 (GIII). Distúrbios clínicos afetaram 57,1% (GI), 75,0% (GII) e 16,7% (GIII) das crias de cabras reinfectados com T. gondii. A toxoplasmose congênita em crias das cabras reinfectadas com T. gondii resultou na perda de 26,5% da receita bruta, sendo GI (US $ 10,577.60 e 57,1%) e GII (US $ 12,693.12 e 60.0%) os detentores dos mais altos valores e porcentagens de perdas econômicas. Verificou-se que a reinfecção toxoplásmica congênita causa distúrbios clínicos em cabras cronicamente infectadas com T. gondii e sua prole com o nascimento de animais inviáveis e perda de receita bruta, em diferentes fases da gestação (40, 80 e 120 dias de gestação)...

Baffled primary facultative ponds with inlets and outlets set at different levels treating domestic wastewater in northeast Brazil.

This study evaluates the performance of four 2.3 m deep pilot-scale, independently loaded, primary facultative ponds treating predominantly domestic sewage in northeast Brazil. The ponds contained longitudinal baffles giving different length to width ratios from 3.55 to 32.4. The ponds had mean hydraulic retention times of ~15 days, and mean surface organic loadings of 330 kg BOD(5).ha.d(-1) during the first experimental phase and 375 kg BOD(5).ha.d(-1) in the second. The vertical inlets and outlets pipes were positioned at 1.8 m and 5 cm respectively below the pond surface in the first phase and at 50 cm and 1.8 m respectively in the second. All the ponds functioned as efficient primary facultative ponds but statistical analysis demonstrated no differences in effluent quality for most of the parameters measured for the various configurations of baffles and inlet and outlet depths. All behaved similarly to the unbaffled pond. The only exceptions were suspended solids and chlorophyll a concentrations which tended to be lower for all combinations of baffles with the outlets set 1.8 m below the surface. This study suggested that the longitudinal baffling of primary facultative ponds when using vertical inlets and outlets may well not significantly improve pond performance.

The removal of ammonia from sanitary landfill leachate using a series of shallow waste stabilization ponds.

This study evaluated the efficiency of a shallow (0.5 m deep) waste stabilization pond series to remove high concentrations of ammonia from sanitary landfill leachate. The pond system was located at EXTRABES, Campina Grande, Paraiba, Northeast Brazil. The pond series was fed with sanitary landfill leachate transported by road tanker to the experimental site from the sanitary landfill of the City of Joao Pessoa, Paraiba. The ammoniacal-N surface loading on the first pond of the series was equivalent to 364 kg ha(-1) d(-1) and the COD surface loading equivalent to 3,690 kg ha(-1) d(-1). The maximum mean ammonia removal efficiency was 99.5% achieved by the third pond in the series which had an effluent concentration of 5.3 mg L(-1) ammoniacal-N for an accumulative HRT of 39.5 days. The removal process was mainly attributed to ammonia volatilization (stripping) from the pond surfaces as a result of high surface pH values and water temperatures of 22-26°C. Shallow pond systems would appear to be a promising technology for stripping ammonia from landfill leachate under tropical conditions.

Exercise-induced bronchospasm in obese adolescents.

BACKGROUND: Assess the frequency and severity of exercise-induced bronchospasm (EIB) in obese adolescents. METHODS: A cross-sectional descriptive study involving 80 adolescents of both genders, aged 10-16 years-old, divided into four groups according to clinical history of asthma and/or allergic rhinitis and body mass index as follows: asthmatic obese (n = 18); asthmatic non-obese (n = 21); obese non-asthmatic (n = 26); and healthy individuals (n = 15). An exercise bronchoprovocation test was used for EIB diagnosis, considered positive when the forced expiratory volume in one second (FEV(1)) decreased > or = 15% in relation to pre-exercise FEV(1). Maximum percent fall in FEV(1) (MF%FEV(1)) and area above the curve (AAC(0-30)) were calculated to evaluate EIB severity and recovery. RESULTS: No significant difference was found in EIB frequency between asthmatic obese (50.0%) and asthmatic non-obese (38.0%) individuals or between obese non-asthmatics (11.5%) and healthy individuals (6.7%). However, the MF%FEV(1) and AAC(0-30) were significantly greater in the asthmatic obese group compared to the asthmatic non-obese (37.7% and 455 vs 24.5% and 214, p<0.03). CONCLUSIONS: Obesity did not contribute to increased EIB frequency in asthmatics and non-asthmatics. However, obesity did contribute to increased EIB severity and recovery among asthmatics.

Exercise-induced bronchospasm in obese adolescents

Background Assess the frequency and severity of exercise-induced bronchospasm (EIB) in obese adolescents. Methods A cross-sectional descriptive study involving 80 adolescents of both genders, aged 10-16 years-old, divided into four groups according to clinical history of asthma and/or allergic rhinitis and body mass index as follows: asthmatic obese (n=18); asthmatic non-obese (n=21); obese non-asthmatic (n=26); and healthy individuals (n=15). An exercise bronchoprovocation test was used for EIB diagnosis, considered positive when the forced expiratory volume in one second (FEV1) decreased ≥15% in relation to pre-exercise FEV1. Maximum percent fall in FEV1 (MF%FEV1) and area above the curve (AAC0_30) were calculated to evaluate EIB severity and recovery. Results No significant difference was found in EIB frequency between asthmatic obese (50.0%) and asthmatic non-obese (38.0%) individuals or between obese non-asthmatics (11.5%) and healthy individuals (6.7%). However, the MF%FEV1 and AAC0_30 were significantly greater in the asthmatic obese group compared to the asthmatic non-obese (37.7% and 455 vs 24.5% and 214, p<0.03). Conclusions Obesity did not contribute to increased EIB frequency in asthmatics and non-asthmatics. However, obesity did contribute to increased EIB severity and recovery among asthmatics (AU)

Prevalence of anti-Toxoplasma gondii antibodies in dairy cattle, dogs, and humans from the Jauru micro-region, Mato Grosso state, Brazil.

In order to determine the prevalence of anti-Toxoplasma gondii antibodies, 2000 serum samples from female dairy cattle belonging to 50 farms in the southwest of Mato Grosso state were analyzed by the indirect fluorescent antibody test (IFAT> or =64). Serum samples from 61 dogs (IFAT> or =40) and 116 humans (IFAT=40), all from the same farm, were also tested. Among these samples, 1420 (71.0%) cattle, 54 (88.5%) dogs, and 113 (97.4%) humans were seropositive for the infection. No significant differences (P> or =0.05) were observed for risk factors associated with the occurrence of toxoplasmosis in humans due to contaminated sources such as fresh milk, cheese/sausage, and contact with felines or other animals. The presence of felines can indicate the likelihood of a contaminated environment, posing a risk to the human population and other animals. The work presented herein is the first report to evaluate the seroprevalence of T. gondii in bovines from the Southwest region of the Mato Grosso state, Brazil.

Effects of physical exercise and nutritional guidance on metabolic syndrome in obese adolescents / Efeito do exercício físico e da orientação nutricional na síndrome metabólica em adolescentes obesos

OBJECTIVES: To analyze the effects of physical exercise and nutritional guidance on body composition, physical fitness, lipid profile and insulin resistance among obese adolescents with and without metabolic syndrome. METHODS: Sixty-four obese adolescents (26 boys), 10-16 years of age, were divided into two groups: with metabolic syndrome (n=29) and without metabolic syndrome (n=35). They were classified as having metabolic syndrome if they met three or more criteria for age and sex according to the Adult Treatment Panel III (ATP III). Blood pressure, waist circumference, maximum oxygen uptake (VO2peak), blood glucose, blood insulin, homeostatic model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI) and lipid profile were assessed at baseline and after 12 weeks of intervention. Both groups participated in 12 weeks of physical education and two nutritional guidance sessions. Each physical education session consisted of 50 min indoor cycling, 50 min of walking/running and 20 min of stretching, three times a week. RESULTS: Fifty-five participants (with metabolic syndrome=25; without metabolic syndrome=30) completed the treatment. After 12 weeks, both groups showed reductions in body weight, BMI z-score, waist circumference, fat mass and triglycerides; and increases in height, HDL-C and VO2peak (p<0.05). In addition, the group with metabolic syndrome presented reduced systolic blood pressure and increased insulin sensitivity (p<0.05). The risk factors for metabolic syndrome decreased by 72 percent. CONCLUSION: Following the multidisciplinary intervention, the risk factors decreased, with improvements in physical fitness and metabolic profile. The multidisciplinary intervention was effective in reducing metabolic syndrome.

OBJETIVOS: Analisar os efeitos de exercícios físicos (EF) e orientação nutricional (ON) sobre a composição corporal, aptidão física, perfil lipídico e resistência insulínica em adolescentes obesos com e sem síndrome metabólica (SM). MÉTODOS: 64 obesos (26 meninos), com idade entre 10 a 16 anos, divididos em dois grupos: com SM (n=29) e sem SM (n=35). Utilizou-se como critério de classificação de SM a presença de três ou mais critérios para idade e sexo de acordo com Adult Treatment Panel III (ATP III). Mensuraram-se antes e após 12 semanas de intervenção: pressão arterial, circunferência abdominal, consumo máximo de oxigênio (VO2pico), glicemia, insulinemia, Homeostatic Metabolic Assessments (HOMA-IR), Quantitative Insulin Sensitivity Check Index (QUICKI) e perfil lipídico. Os dois grupos participaram de 12 semanas de EF e duas sessões de ON. Cada sessão de EF consistiu em 50 minutos de ciclismo indoor, 50 minutos de caminhada e 20 minutos de alongamento, três vezes por semana. RESULTADOS: 55 sujeitos (com SM=25; sem SM=30) completaram o tratamento. Após 12 semanas, houve diminuição na massa corporal, IMC escore-z, circunferência abdominal, massa gorda, TG e aumento na estatura, HDL-C e VO2pico, em ambos os grupos. Além disso, houve uma redução na pressão arterial sistólica, aumento na sensibilidade à insulina (p<0,05) no grupo com SM. Os fatores de risco para SM diminuíram em 72 por cento. CONCLUSÃO: Após a intervenção multidisciplinar, houve uma redução nos fatores de risco, melhorando a aptidão física e perfil metabólico. A intervenção multidisciplinar foi efetiva para redução da SM.

Semen variables of sheep (Ovis aries) experimentally infected with Toxoplasma gondii.

The influence of Toxoplasma gondii on semen variables and sperm morphology of sheep was evaluated in eight reproductive males distributed into three experimental groups: GI, three sheep inoculated with 2.0x10(5) of P strain oocytes; GII, three sheep infected with 1.0x10(6) of RH strain tachyzoites and; GIII two control sheep. Clinical (rectal temperature, cardiac and respiratory frequencies), parasite and serology exams (IIF) were realized. Sperm variables (volume, motility, vigor and concentration) and semen morphology for each sheep were also evaluated. Thus, semen and blood collections were assessed on post-inoculation days (PIDs)-1,3,5,7,11,14 and weekly thereafter up to PID 70. Clinical alterations were observed (hypothermia and anorexia) in infected sheep from groups GI and GII. Parasitic outbreaks were detected in five sheep. All the infected sheep produced antibodies against T. gondii from PID 5 onwards, reaching a peak of 4096 and 8192 for group GI and GII sheep, respectively. Differences (P<0.05) were observed regarding the ejaculate volume between the inoculated groups (oocytes and tachyzoites) and control. Even though experimental toxoplasmic infection resulted in clinical symptomology in the inoculated sheep, the minimal alterations in sperm pathologies could not be directly attributed to T. gondii.

Nonequilibrium self-assembly of metals on diblock copolymer templates.

Most studies of self-assembled systems reveal that the highest order is associated with equilibrium states of the system. By systematically studying metal decoration of diblock copolymer templates, I show that a high degree of order can arise under strongly nonequilibrium conditions. Under a wide range of conditions, thermally evaporated gold decorates ultrathin, asymmetric, polystyrene-b-polymethylmethacrylate diblock copolymer films with isolated nanoparticles. These particles aggregate into nanoparticle chains inside the polystyrene block with a selectivity approaching 100%. However, even at metal loading fractions of up to 30% by volume no coalescence into continuous nanowires is observed. This behavior is also shared by indium, tin, lead, bismuth, and silver at low coverage (<30 A nominal thickness). At high coverage (>100 A nominal thickness), however, silver self-assembles to form nanowires. One can understand the formation of the chains of nanoparticles by understanding the equilibrium state of the system (metal+polymer). The silver nanowires are highly nonequilibrium structures and, to the best of my knowledge, unexplained by existing theoretical models. Assuming an energy difference for metallic particles for either side of the diblock, a mobility difference, and an attractive interaction between metallic particles, I modeled the self-assembly of the nanowires with a Monte Carlo simulation. This Monte Carlo simulation qualitatively agrees with the formation of the silver nanowires and their relaxation to equilibrium upon moderate heating.

Hierarchical self-assembly of metal nanostructures on diblock copolymer scaffolds.

Self-assembly is emerging as an elegant, 'bottom-up' method for fabricating nanostructured materials. This approach becomes particularly powerful when the ease and control offered by the self-assembly of organic components is combined with the electronic, magnetic or photonic properties of inorganic components. Here we demonstrate a versatile hierarchical approach for the assembly of organic-inorganic, copolymer-metal nanostructures in which one level of self-assembly guides the next. In a first step, ultrathin diblock copolymer films form a regular scaffold of highly anisotropic, stripe-like domains. During a second assembly step, differential wetting guides diffusing metal atoms to aggregate selectively along the scaffold, producing highly organized metal nanostructures. We find that, in contrast to the usual requirement of near-equilibrium conditions for ordering, the metal arranged on the copolymer scaffold produces the most highly ordered configurations when the system is far from equilibrium. We delineate two distinct assembly modes of the metal component-chains of separate nanoparticles and continuous wires-each characterized by different ordering kinetics and strikingly different current-voltage characteristics. These results therefore demonstrate the possibility of guided, large-scale assembly of laterally nanostructured systems.

Quimioprofilaxia da doença de Chagas: bloqueio da transmissão transfusional por produtos naturais / Chemyprophylaxis of Chagas disease: blockage of blood transfusion transmission by natural products

Em busca da solução para o serio problema da transmissão transfusional da doença de Chagas em nosso meio, realizamos a avaliação de produtos naturais corn atividade tripanosomicida. Os testes "in vitro" foram realizados incubando-se a 4°C, sangue de camundongos contendo ± 10(6)/ ml formas tripomastigotas de Trypanosoma cruzi corn os extratos vegetais. Após diferentes períodos de incubação, frações sangüíneas foram examinadas em microscopia de fase. Os extratos que apresentaram atividade tripanosomicida ate 48 horas de incubação, foram examinados em microscopia eletrônica corn intuito de verificarmos sua toxicidade contra os elementos normais do sangue. Foram testados 242 extratos obtidos de 81 vegetais a 56 demonstraram atividade.

Considering the serius problem of blood transfusion transmission of Chagas disease in our environment, we realized the evalution of natural products against Chagas diseases. The tests were realized "in vitro" by in incubation at 4ºC mouse blood having ± 10(6)/ml of Trypanosoma cruzi, sample "y" and "Colombina" with the plant extracts. After different times of incubation, blood fractions were examined by phase microscopy. The drugs that showed activity until 48 hours of incubation, were examined by electron microscopy to virify the toxicity to blood elements. The tests were realized with 242 extracts from 81 plants and 56 extracts showed activity against T. cruzi.