3,084 research outputs found
Cobalt-catalysed site-selective intra- and intermolecular dehydrogenative amination of unactivated sp3 carbons
Cobalt-catalysed sp2 C–H bond functionalization has attracted considerable attention in recent years because of the low cost of cobalt complexes and interesting modes of action in the process. In comparison, much less efforts have been devoted to the sp3 carbons. Here we report the cobalt-catalysed site-selective dehydrogenative cyclization of aliphatic amides via a C–H bond functionalization process on unactivated sp3 carbons with the assistance of a bidentate directing group. This method provides a straightforward synthesis of monocyclic and spiro β- or γ-lactams with good to excellent stereoselectivity and functional group tolerance. In addition, a new procedure has been developed to selectively remove the directing group, which enables the synthesis of free β- or γ-lactam compounds. Furthermore, the first cobalt-catalysed intermolecular dehydrogenative amination of unactivated sp3 carbons is also realized.,
Functionalizing unactivated carbon–hydrogen bonds is challenging, especially when using non-precious metals and dealing with sp3 hybridized carbons. Here, the authors report an intramolecular cobalt catalysed amination of C–H bonds of sp3 carbons, giving access to β- and γ-lactams
Assessing Cross Laminated Timber (CLT) as an Alternative Material for Mid-Rise Residential Buildings in Cold Regions in China—A Life-Cycle Assessment Approach
Timber building has gained more and more attention worldwide due to it being a generic renewable material and having low environmental impact. It is widely accepted that the use of timber may be able to reduce the embodied energy of a building. However, the development of timber buildings in China is not as rapid as in some other countries. This may be because of the limitations of building regulations and technological development. Several new policies have been or are being implemented in China in order to encourage the use of timber in building construction and this could lead to a revolutionary change in the building industry in China. This paper is the first one to examine the feasibility of using Cross Laminated Timber (CLT) as an alternative solution to concrete by means of a cradle-to-grave life-cycle assessment in China. A seven-storey reference concrete building in Xi’an was selected as a case study in comparison with a redesigned CLT building. Two cities in China, in cold and severe cold regions (Xi’an and Harbin), were selected for this research. The assessment includes three different stages of the life span of a building: materialisation, operation, and end-of-life. The inventory data used in the materialisation stage was mostly local, in order to ensure that the assessment appropriately reflects the situation in China. Energy consumption in the operation stage was obtained from simulation by commercialised software IESTM, and different scenarios for recycling of timber material in the end-of-life are discussed in this paper. The results from this paper show that using CLT to replace conventional carbon intensive material would reduce energy consumption by more than 30% and reduce CO2 emission by more than 40% in both cities. This paper supports, and has shown the potential of, CLT being used in cold regions with proper detailing to minimise environmental impact
A Prospective Randomized Study of Adjuvant Chemotherapy in Resected Stage IIIA-N2 Non-small Cell Lung Cancer
Background and objective Lung cancer is one of the leading cause of cancer-related death around the world. Surgery is the primary treatment for patients with stage I, II, or IIIA non-small cell lung cancer (NSCLC). However, longterm survival of NSCLC patients after surgery alone is largely unsatisfactory. We undertook to determine whether adjuvant vinorelbine/paclitaxel plus carboplatin prolong overall survival among patients with completely resected stage IIIA-N2 nonsmall cell lung cancer. Methods We randomly assigned patients with completely resected stage IIIA-N2 non-small cell lung cancer to vinorelbine/paclitaxel plus carboplatin or to observation. Results A total of 150 patients (1999-2003) underwent randomization to vinorelbine/paclitaxel plus carboplatin (79 patients) or observation. In both groups, the median age was 57 years, 73 percent were male, and 28 percents had squamous carcinoma. Chemotherapy caused neutropenia in 82 percents of patients (including grade 3 and 4 neutropenia in 42 percent) and there was no treatment-related death observed in this trial. After median follow-up of 39 months (range 1-110), overall survival was significantly prolonged in the chemotherapy group as compared with the observation group (33 months versus 24 months, χ2=4.363, P=0.037), as was disease-free survival (32 months versus 20 months, χ2=5.413, P=0.020). Five-year overall survival rates were 31.1 percent and 19.1 percent, respectively. Conclusion Adjuvant vinorelbine/paclitaxel plus carboplatin have an acceptable level of toxicity and prolongs disease-free and overall survival among patients with completely resected stage IIIA-N2 non-small cell lung cancer
Energy Saving and Carbon Reduction in the Operation Stage of Cross Laminated Timber Residential Buildings in China
This paper focused on energy consumption and carbon emission for heating and cooling
during a building’s operation stage, and examined the energy effects of using Cross Laminated
Timber (CLT) as an alternative building material to reinforced concrete (RC) in China’s 31 key cities
located in different climate zones. The authors designed two seven-story residential buildings, which
were constructed with RC framed and CLT systems, separately. This was followed by simulating the
energy consumption using commercialized software IESTM under the different climate zones and
calculating the carbon emissions. Comparisons were made between RC and CLT systems buildings
on the basis of simulation data. The results show that the estimated energy consumption and carbon
emission in CLT buildings are much lower than that of RC buildings in all studied cities, which
indicates that CLT systems have good potential in reducing carbon emission and saving energy
consumption compared to RC. The energy consumptions and carbon emissions in both concrete and
CLT buildings are closely related to the climate zones. Buildings in Severe Cold and Cold Regions
consumed the most energy and released more carbon. At the national level, the estimated energy
consumption at the operation stage, in the studied building with RC frames and CLT system was
approximately 465.1 MJ/m2 and 332.6 MJ/m2 per annum, respectively. Despite vast differences in
China’s climate zones, the effects of energy saving and carbon reduction potentials of CLT buildings
show little relationship to the climate zone. CLT buildings may result in a weighted 29.4% energy
saving, which equals 24.6% carbon reductions, compared with RC buildings at the operation stage at
national level, although it may vary in different climate zones
Use of parenteral caffeinum natrio-benzoicum: an underestimated risk factor for HCV transmission in China
Health-related quality of life as measured with EQ-5D among populations with and without specific chronic conditions: A population-based survey in Shaanxi province, China
© 2013 Tan et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Introduction: The aim of this study was to examine health-related quality of life (HRQoL) as measured by EQ-5D and to investigate the influence of chronic conditions and other risk factors on HRQoL based on a distributed sample located in Shaanxi Province, China. Methods: A multi-stage stratified cluster sampling method was performed to select subjects. EQ-5D was employed to measure the HRQoL. The likelihood that individuals with selected chronic diseases would report any problem in the EQ-5D dimensions was calculated and tested relative to that of each of the two reference groups. Multivariable linear regression models were used to investigate factors associated with EQ VAS. Results: The most frequently reported problems involved pain/discomfort (8.8%) and anxiety/depression (7.6%). Nearly half of the respondents who reported problems in any of the five dimensions were chronic patients. Higher EQ VAS scores were associated with the male gender, higher level of education, employment, younger age, an urban area of residence, access to free medical service and higher levels of physical activity. Except for anemia, all the selected chronic diseases were indicative of a negative EQ VAS score. The three leading risk factors were cerebrovascular disease, cancer and mental disease. Increases in age, number of chronic conditions and frequency of physical activity were found to have a gradient effect. Conclusion: The results of the present work add to the volume of knowledge regarding population health status in this area, apart from the known health status using mortality and morbidity data. Medical, policy, social and individual attention should be given to the management of chronic diseases and improvement of HRQoL. Longitudinal studies must be performed to monitor changes in HRQoL and to permit evaluation of the outcomes of chronic disease intervention programs. © 2013 Tan et al.National Nature Science Foundation (No. 8107239
The Plastic Scintillator Detector at DAMPE
he DArk Matter Particle Explorer (DAMPE) is a general purposed
satellite-borne high energy ray and cosmic ray detector, and among the
scientific objectives of DAMPE are the searches for the origin of cosmic rays
and an understanding of Dark Matter particles. As one of the four detectors in
DAMPE, the Plastic Scintillator Detector (PSD) plays an important role in the
particle charge measurement and the photons/electrons separation. The PSD has
82 modules, each consists of a long organic plastic scintillator bar and two
PMTs at both ends for readout, in two layers and covers an overall active area
larger than 82 cm 82 cm. It can identify the charge states for
relativistic ions from H to Fe, and the detector efficiency for Z=1 particles
can reach 0.9999. The PSD has been successfully launched with DAMPE on Dec. 17,
2015. In this paper, the design, the assembly, the qualification tests of the
PSD and some of the performance measured on the ground have been described in
detail
- …
