6,286 research outputs found
Effect of Water Content on the Thermal Inactivation Kinetics of Horseradish Peroxidase Freeze-Dried from Alkaline pH
The thermal inactivation of horseradish peroxidase freeze-dried from solutions of different pH (8, 10 and 11.5, measured at 25 C) and equilibrated to different water contents was studied in the temperature range from 110 to 150 C. The water contents studied (0.0, 1.4, 16.2 and 25.6 g water per 100 g of dry enzyme) corresponded to water activities of 0.0, 0.11, 0.76 and 0.88 at 4 C. The kinetics were well described by a double exponential model. The enzyme was generally more stable the lower the pH of the original solution, and for all pH values, the maximum stability was obtained at 1.4 g water/100 g dry enzyme. Values of z were generally independent of water content and of the pH of the original solution, and in the range of 15–25 °C, usually found in neutral conditions, with the exception of the enzyme freeze dried from pH 11.5 and equilibrated with phosphorus pentoxide, where a z-value of the stable fraction close to 10 C was found
Characterization of three types of silicon solar cells for SEPS Deep Space Mission. Volume 3: Current-voltage characteristics of spectrolab sculptured BSR/P+ (K7), BSR/P+ (K6.5) and BSR (K4.5) cells as a function of temperature and intensity
Three types of high performance silicon solar cells, sculptured BSR/P+(K7), BSR/P+(K6.5) and BSR(K4.5) manufactured by Spectrolab were evaluated for their low temperature and low intensity performance. Sixteen cells of each type were subjected to 11 temperatures and 9 intensities. The sculptured BSR/P+(K7) cells provided the greatest maximum power output both at 1 AU and at LTLI conditions. The average efficiencies of this cell were 14.4 percent at 1 SC/+25 deg C and 18.5 percent at 0.086 SC/-100 deg C
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Al0.2Ga0.8As 2 × 2 square pixel X-ray photodiode array
A monolithic 2 × 2 square pixel Al0.2Ga0.8As p+-i-n+ mesa X-ray photodiode array (each photodiode area 200 µm by 200 µm, 3 µm i layer) has been fabricated from material grown by MOVPE. The array was electrically characterised across the temperature range 100 °C to -20 °C. Each pixel’s response to illumination with soft X rays from an 55Fe radioisotope X-ray source (Mn Kα = 5.9 keV; Mn Kβ = 6.49 keV) was investigated across the temperature range 30 °C to -20 °C. The best energy resolution (FWHM at 5.9 keV) achieved at 20 °C was 0.76 keV ± 0.06 keV (with 30 V reverse bias applied to the detector). The measured energy resolution is the best so far reported for AlGaAs X-ray photodiodes at 20 °C. It is also the first time a small AlGaAs X-ray photodiode array has been demonstrated. Due to the temperature tolerance and the radiation hardness of AlGaAs, such detectors are expected to find utility in future space science missions exposed to intense radiation environments, for example missions to study the Jovian or Saturnian aurorae and high temperature planetary surfaces
An In Situ Study of the Role of Pressure on Fe Recrystallization and Grain Growth during Thermomechanical Processing
Elevated pressures are encountered in many metal forming processes that can
alter microstructural evolution rates. Here we measure rate changes with
pressure in recrystallization and grain growth in Fe through adaptation of
synchrotron-compatible multi-anvil presses, originally designed for study of
the mantle. Recrystallization and grain growth are monitored in situ using
high-energy X-ray diffraction. Principal component analysis applied to the
diffraction images is used to quantify evolution rates, with increasing
pressure significantly slowing the process
Aspectos artÃsticos da História Cultura de Araraquara
This text celebrates Araraquara’s birthday, in August, on the eve of its second centenary (1817-2015). It is a homage to its expressive cultural heritage, highlighting artistic and intellectual aspects of its history in the first half of the last century. Considering this, it rescues the extraordinary development in two important areas: theater and plastic arts, emphasizing the singularity of these manifestations and the main involved protagonists. Deepening the historical view, it also captures some contradictions.Este texto celebra o aniversário de Araraquara, no mês de agosto, à s vésperas do seu segundo centenário (1817-2015). Homenageia seu expressivo legado cultural, destacando aspectos artÃsticos e intelectuais de sua História na primeira metade do século passado. Para tanto, resgata o extraordinário desenvolvimento de duas áreas importantes: teatro e artes plásticas, enfatizando a singularidade dessas manifestações e os principais protagonistas envolvidos. Aprofundando a visão histórica, capta, ainda, algumas contradições
Characterization of a 5-eV neutral atomic oxygen beam facility
An experimental effort to characterize an existing 5-eV neutral atomic oxygen beam facility being developed at Princeton Plasma Physics Laboratory is described. This characterization effort includes atomic oxygen flux and flux distribution measurements using a catalytic probe, energy determination using a commercially designed quadrupole mass spectrometer (QMS), and the exposure of oxygen-sensitive materials in this beam facility. Also, comparisons were drawn between the reaction efficiencies of materials exposed in plasma ashers, and the reaction efficiencies previously estimated from space flight experiments. The results of this study show that the beam facility is capable of producing a directional beam of neutral atomic oxygen atoms with the needed flux and energy to simulate low Earth orbit (LEO) conditions for real time accelerated testing. The flux distribution in this facility is uniform to +/- 6 percent of the peak flux over a beam diameter of 6 cm
AlGaAs 55Fe X-ray radioisotope microbattery
This paper describes the performance of a fabricated prototype Al0.2Ga0.8As 55Fe radioisotope microbattery photovoltaic cells over the temperature range −20 °C to 50 °C. Two 400 μm diameter p+-i-n+ (3 μm i-layer) Al0.2Ga0.8As mesa photodiodes were used as conversion devices in a novel X-ray microbattery prototype. The changes of the key microbattery parameters were analysed in response to temperature: the open circuit voltage, the maximum output power and the internal conversion efficiency decreased when the temperature was increased. At −20 °C, an open circuit voltage and a maximum output power of 0.2 V and 0.04 pW, respectively, were measured per photodiode. The best internal conversion efficiency achieved for the fabricated prototype was only 0.95% at −20 °C
Cytomegalovirus-associated pulmonary exacerbation in patients with cystic fibrosis.
CMV is an unusual cause of pulmonary exacerbation in immunocompetent individuals with CF http://ow.ly/Rdds30hlnjV
The role of chronic conditions in influencing symptom attribution and anticipated help-seeking for potential lung cancer symptoms: a vignette-based study
BACKGROUND: Very little is known about the influence of chronic conditions on symptom attribution and help-seeking for potential cancer symptoms. AIM: To determine if symptom attribution and anticipated help-seeking for potential lung cancer symptoms is influenced by pre-existing respiratory conditions (often referred to as comorbidity), such as asthma or chronic obstructive pulmonary disease (COPD). DESIGN & SETTING: A total of 2143 adults (1081 with and 1062 without a respiratory condition) took part in an online vignette survey. METHOD: The vignette described potential lung cancer symptoms (persistent cough and breathlessness) after which questions were asked on symptom attribution and anticipated help-seeking. RESULTS: Attribution of symptoms to cancer was similar in participants with and without respiratory conditions (21.5% and 22.1%, respectively). Participants with respiratory conditions, compared with those without, were more likely to attribute the new or changing cough and breathlessness to asthma or COPD (adjusted odds ratio [OR] = 3.64, 95% confidence interval [CI] = 3.02 to 4.39). Overall, 56.5% of participants reported intention to seek help from a GP within 3 weeks if experiencing the potential lung cancer symptoms. Having a respiratory condition increased the odds of prompt help-seeking (OR = 1.25, 95% CI = 1.04 to 1.49). Regular healthcare appointments were associated with higher odds of anticipated help-seeking. CONCLUSION: Only one in five participants identified persistent cough and breathlessness as potential cancer symptoms, and half said they would promptly seek help from a GP, indicating scope for promoting help-seeking for new or changing symptoms. Chronic respiratory conditions did not appear to interfere with anticipated help-seeking, which might be explained by regular appointments to manage chronic conditions
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