DNA-Powered Stimuli-Responsive Single-Walled Carbon Nanotube Junctions

Reconfigurable stimuli-responsive molecular materials play an important role in the fabrication of nanoscale systems and devices. Here, we report a bottom-up strategy for the reversible assembly of single-walled carbon nanotube linear junctions in solution. The assembly/disassembly of the nanotubes can be controlled via the intrinsic responsiveness to different stimuli of sequence-specific deoxyribonucleic acid linkers forming the junctions

The dependence of the proton-triton thermo-nuclear fusion reaction rate on the temperature and total energy content of the high-energy proton distribution function

The endothermic nuclear reaction between thermal tritons and high-energy protons can represent an important contribution to the total neutron yield in tokamak plasmas heated by radio-frequency waves, as the first JET experiments have demonstrated (see Mantsinen et al 2001 Nucl. Fusion 41 1815). A further study based on more recent JET experiments was reported in Santala et al 2006 (Plasma Phys. Control. Fusion 48 1233). In this letter we supplement and complete the previous analysis by reporting the first systematic measurement of the scaling of the proton-triton (pT) thermo-nuclear fusion reaction rate as a function of the total energy content and perpendicular tail temperature of the fast protons heated by radio-frequency waves. It is found that the pT-neutron rate increases almost linearly with the fast proton temperature and the total energy content

DNA-Driven Dynamic Assembly of MoS2 Nanosheets

Controlling the assembly of molybdenum disulfide (MoS2) layers into static and dynamic superstructures can impact on their use in optoelectronics, energy, and drug delivery. Toward this goal, we present a strategy to drive the assembly of MoS2 layers via the hybridization of complementary DNA linkers. By functionalizing the MoS2 surface with thiolated DNA, MoS2 nanosheets were assembled into mulitlayered superstructures, and the complementary DNA strands were used as linkers. A disassembly process was triggered by the formation of an intramolecular i-motif structure at a cystosine-rich sequence in the DNA linker at acidic pH values. We tested the versatility of our approach by driving the disassembly of the MoS2 superstructures through a different DNA-based mechanism, namely strand displacement. This study demonstrates how DNA can be employed to drive the static and dynamic assembly of MoS2 nanosheets in aqueous solution

Parotidite aguda pós-cirúgica: prevalência atual no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo

Postsurgical acute suppurative parotitis is a bacterial gland infection that occurs from a few days up to some weeks after abdominal surgical procedures. In this study, the authors analyze the prevalence of this complication in Hospital das Clínicas/São Paulo University Medical School by prospectively reviewing the charts of patients who underwent surgeries performed by the gastroenterological and general surgery staff from 1980 to 2005. Diagnosis of parotitis or sialoadenitis was analyzed. Sialolithiasis and chronic parotitis previous to hospitalization were exclusion criteria. In a total of 100,679 surgeries, 256 patients were diagnosed with parotitis or sialoadenitis. Nevertheless, only three cases of acute postsurgical suppurative parotitis associated with the surgery were identified giving an incidence of 0.0028%. All patients presented with risk factors such as malnutrition, immunosuppression, prolonged immobilization and dehydration. In the past, acute postsurgical suppurative parotitis was a relatively common complication after major abdominal surgeries. Its incidence decreased as a consequence of the improvement of perioperative antibiotic therapy and postoperative support. In spite of the current low incidence, we believe it is important to identify risks and diagnose as quick as possible, in order to introduce prompt and appropriate therapeutic measures and avoid potentially fatal complications with the evolution of the disease.A parotidite supurativa pós-cirúrgica é infecção bacteriana da glândula que ocorre poucos dias até algumas semanas após procedimento cirúrgico. Os autores analisam a prevalência desta complicação cirúrgica nos últimos 25 anos do Hospital das Clínicas de São Paulo. Foram analisados os prontuários das cirurgias realizadas pelos serviços de Cirurgia do Aparelho Digestivo e Cirurgia Geral da Faculdade de Medicina da Universidade de São Paulo no período de 1980 a 2005, num total de 106790 cirurgias. Todos os prontuários que apresentaram entre os diagnósticos das altas complicações cirúrgicas, parotidite ou sialoadenite foram avaliados. Foram identificados 256 prontuários. Pacientes com outras complicações, ou que já apresentavam sialolitíase ou parotidite crônica anterior à internação foram excluídos do estudo. Foram identificados apenas três casos de parotidite aguda supurativa pós-cirúrgica, revelando incidência de 0,0028%. A parotidite supurativa pós-cirúrgica foi complicação relativamente comum de grandes cirurgias abdominais no passado, com acentuada redução atual da sua incidência decorrente da antibioticoterapia de amplo espectro, além de preparação pré-operatória adequada e suporte pós-operatório dos pacientes. Apesar da baixa incidência atual, consideramos importante identificar seus fatores de risco, assim como realizar diagnóstico precoce, conduta terapêutica apropriada para evitar complicações letais associadas a esta infecção