New important applications of copper metal, e.g., in the areas of hydrogen production, fuel cell operation, and spent nuclear fuel disposal, require accurate knowledge of the physical and chemical properties of stable and metastable copper compounds. Among the copper(I) compounds with oxygen and hydrogen, cuprous oxide Cu(2)O is the only one stable and the best studied. Other such compounds are less known (CuH) or totally unknown (CuOH) due to their instability relative to the oxide. Here we combine quantum-mechanical calculations with experimental studies to search for possible compounds of monovalent copper. Cuprous hydride (CuH) and cuprous hydroxide (CuOH) are proved to exist in solid form. We establish the chemical and physical properties of these compounds, thereby filling the existing gaps in our understanding of hydrogen- and oxygen-related phenomena in Cu metal. 相似文献
This study aimed at evaluating the degree of conversion (DC) of four composite
resins, being one nanofilled and 3 microhybrid resins, photo-activated with
second- and third-generation light-emitting diodes (LEDs).
Material and methods
FiltekTM Z350 nanofilled composite resins and Amelogen®
Plus, Vit-l-escenceTM and Opallis microhybrid resins were
photo-activated with two second-generation LEDs (Radii-cal and Elipar Free
LightTM 2) and one third-generation LED (Ultra-Lume LED 5) by
continuous light mode, and a quartz halogen-tungsten bulb (QHT, control). After 24
h of storage, the samples were pulverized into fine powder and 5 mg of each
material were mixed with 100 mg of potassium bromide (KBr). After homogenization,
they were pressed, which resulted in a pellet that was evaluated using an infrared
spectromer (Nexus 470, Thermo Nicolet) equipped with TGS detector using diffuse
reflectance (32 scans, resolution of 4 cm-1) coupled to a computer. The
percentage of unreacted carbon-carbon double bonds (% C=C) was determined from the
ratio of absorbance intensities of aliphatic C=C (peak at 1637 cm-1) against
internal standard before and after curing of the specimen: aromatic C-C (peak at
1610 cm-1).
Results
The ANOVA showed a significant effect on the interaction between the light-curing
units (LCUs) and the composite resins (p<0.001). The Tukey''s test showed that
the nanofilled resin (FiltekTM Z350) and Opallis when photo-activated
by the halogen lamp (QTH) had the lowest DC compared with the other microhybrid
composite resins. The DC of the nanofilled resin (FiltekTM Z350) was
also lower using LEDs. The highest degrees of conversion were obtained using the
third-generation LED and one of second-generation LEDs (Elipar Free
LightTM 2).
Conclusions
The nanofilled resin showed the lowest DC, and the Vit-l-escenceTM
microhybrid composite resin showed the highest DC. Among the LCUs, it was not
possible to establish an order, even though the second-generation LED Radii-cal
provided the lowest DC. 相似文献
We calculated the light absorbing potential (LAP) of hemoglobin (Hb) and myoglobin (Mb) in mammalian skeletal muscle at rest based on analysis of published chemical and morphometric data (Part 1), interpreted changes in total[Hb + Mb] from NIRS during exercise (Part 2), and estimated the potential contribution of Hb and Mb to changes in NIRS from rest to exercise (Part 3). Part 1: [Hb] in skeletal muscle was estimated from microvascular volume, systemic blood [Hb], and microvascular hematocrit and saturation at rest and during exercise. Part 2: Changes in total[Hb + Mb] (as t[Hb + Mb]) during cycling or knee extension exercise were interpreted using the results of Part 1. Part 3: Using estimates of mean microvascular PO2, Hb and Mb contribution at peak exercise was estimated. Across several species, [Mb] contributed ∼50–70% of the total LAP to NIRS at rest in skeletal muscle. With exercise, increases in t[Hb + Mb] of up to 30% could be entirely explained by the predicted increase in microvascular hematocrit with exercise. Finally, Mb was estimated to contribute ∼70% of the changes in NIRS from rest to peak exercise. 相似文献
Objectives: The purpose of the study was to investigate and characterize the oral lyophilisates containing the pregabalin-acetaminophen drug combination and as xcipients mannitol with microcrystalline cellulose or hydroxypropyl methylcellulose, in order to conclude upon drug-excipient interactions and their stability implications, impact of excipients on drug release and on the physicochemical and mechanical properties of the pharmaceutical formulations.
Methods: The oral tablets were made by using a Christ freeze-dryer alpha 2–4-LSC lyophilizer, and evaluated for stability, drug-excipient compatibility and homogeneity of the prepared pharmaceutical formulations. The formulations were evaluated for in vivo absorption in rabbits by histopathological exams.
Results: FTIR and thermogravimetric analyses, DLS technique, SEM and NIR-CI studies confirmed the compatibility between compounds. From the determined physical and biochemical parameters of the formulations it was established that they are stable, homogeneous, and meet the conditions for orally disintegrating tablets.
Conclusion: In the case of the investigated pharmaceutical formulations the study evidenced the assembling through physical bonds between the excipients and the ‘codrug’ complex, which do not affect the release of the bioactive compounds. 相似文献
Cardiopulmonary bypass (CPB) in infants is associated with morbidity due to systemic inflammatory response syndrome (SIRS). Strategies to mitigate SIRS include management of perfusion temperature, hemodilution, circuit miniaturization, and biocompatibility. Traditionally, perfusion parameters have been based on body weight. However, intraoperative monitoring of systemic and cerebral metabolic parameters suggest that often, nominal CPB flows may be overestimated. The aim of the study was to assess the safety and efficacy of continuous metabolic monitoring to manage CPB in infants during open‐heart repair. Between December 2013 and October 2014, 31 consecutive neonates, infants, and young children undergoing surgery using normothermic CPB were enrolled. There were 18 male and 13 female infants, aged 1.4 ± 1.7 years, with a mean body weight of 7.8 ± 3.8 kg and body surface area of 0.39 m2. The study was divided into two phases: (i) safety assessment; the first 20 patients were managed according to conventional CPB flows (150 mL/min/kg), except for a 20‐min test during which CPB was adjusted to the minimum flow to maintain MVO2 >70% and rSO2 >45% (group A); (ii) efficacy assessment; the following 11 patients were exclusively managed adjusting flows to maintain MVO2 >70% and rSO2 >45% for the entire duration of CPB (group B). Hemodynamic, metabolic, and clinical variables were compared within and between patient groups. Demographic variables were comparable in the two groups. In group A, the 20‐min test allowed reduction of CPB flows greater than 10%, with no impact on pH, blood gas exchange, and lactate. In group B, metabolic monitoring resulted in no significant variation of endpoint parameters, when compared with group A patients (standard CPB), except for a 10% reduction of nominal flows. There was no mortality and no neurologic morbidity in either group. Morbidity was comparable in the two groups, including: inotropic and/or mechanical circulatory support (8 vs. 1, group A vs. B, P = 0.07), reexploration for bleeding (1 vs. none, P = not significant [NS]), renal failure requiring dialysis (none vs. 1, P = NS), prolonged ventilation (9 vs. 4, P = NS), and sepsis (2 vs. 1, P = NS). The present study shows that normothermic CPB in neonates, infants, and young children can be safely managed exclusively by systemic and cerebral metabolic monitoring. This strategy allows reduction of at least 10% of predicted CPB flows under normothermia and may lay the ground for further tailoring of CPB parameters to individual patient needs. 相似文献