161 research outputs found
I. Correlation of Structural Details and Emission Properties of Copper(I)Iodide Complexes with Aliphatic Amines II. Copper(I) Halide ? Complexes
Chemistr
Thermal Properties of Cement-Based Composites for Geothermal Energy Applications
Geothermal energy piles are a quite recent renewable energy technique where geothermal energy in the foundation of a building is used to transport and store geothermal energy. In this paper, a structural–functional integrated cement-based composite, which can be used for energy piles, was developed using expanded graphite and graphite nanoplatelet-based composite phase change materials (CPCMs). Its mechanical properties, thermal-regulatory performance, and heat of hydration were evaluated. Test results showed that the compressive strength of GNP-Paraffin cement-based composites at 28 days was more than 25 MPa. The flexural strength and density of thermal energy storage cement paste composite decreased with increases in the percentage of CPCM in the cement paste. The infrared thermal image analysis results showed superior thermal control capability of cement based materials with CPCMs. Hence, the carbon-based CPCMs are promising thermal energy storage materials and can be used to improve the durability of energy piles
Preparation and Supercooling Modification of Salt Hydrate Phase Change Materials Based on CaCl2 2H2O/CaCl2
Salt hydrates have issues of supercooling when they are utilized as phase change materials
(PCMs). In this research, a new method was adopted to prepare a salt hydrate PCM (based
on a mixture of calcium chloride dihydrate and calcium chloride anhydrous) as a novel PCM
system to reduce the supercooling phenomenon existing in CaCl2 6H2O. Six samples with different
compositions of CaCl2 were prepared. The relationship between the performance and the proportion
of calcium chloride dihydrate (CaCl2 2H2O) and calcium chloride anhydrous (CaCl2) was also
investigated. The supercooling degree of the final PCM reduced with the increase in volume of
CaCl2 2H2O during its preparation. The PCM obtained with 66.21 wt % CaCl2 2H2O reduced the
supercooling degree by about 96.8%. All six samples, whose ratio of CaCl2 2H2O to (CaCl2 plus
CaCl2 2H2O) was 0%, 34.03%, 53.82%, 76.56%, 90.74%, and 100% respectively, showed relatively
higher enthalpy (greater than 155.29 J/g), and have the possibility to be applied in buildings
for thermal energy storage purposes. Hence, CaCl2 2H2O plays an important role in reducing
supercooling and it can be helpful in adjusting the solidification enthalpy. Thereafter, the influence of
adding different percentages of Nano-SiO2 (0.1 wt %, 0.3 wt %, 0.5 wt %) in reducing the supercooling
degree of some PCM samples was investigated. The test results showed that the supercooling of the
salt hydrate PCM in Samples 6 and 5 reduced to 0.2 C and 0.4 C respectively. Finally, the effect of
the different cooling conditions, including frozen storage (20 C) and cold storage (5 C), that were
used to prepare the salt hydrate PCM was considered. It was found that both cooling conditions are
effective in reducing the supercooling degree of the salt hydrate PCM. With the synergistic action of
the two materials, the performance and properties of the newly developed PCM systems were better
especially in terms of reducing the supercooling degree of the PCM. The novel composite PCMs are
promising candidates for thermal energy storage applications
Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles
Energy piles—A fairly new renewable energy concept—Use a ground heat exchanger
(GHE) in the foundation piles to supply heating and cooling loads to the supported building.
Applying phase change materials (PCMs) to piles can help in maintaining a stable temperature
within the piles and can then influence the axial load acting on the piles. In this study, two kinds
of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based
PCM) were prepared by vacuum impregnation for potential application in energy piles. Thereafter,
a systematic study was performed and different characterization tests were carried out on two
composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically
compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g
while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be
37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications
Accuracy of plasma sTREM-1 for sepsis diagnosis in systemic inflammatory patients: a systematic review and meta-analysis
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Genomic regions, cellular components and gene regulatory basis underlying pod length variations in cowpea (V. unguiculata L. Walp).
Cowpea (V. unguiculata L. Walp) is a climate resilient legume crop important for food security. Cultivated cowpea (V. unguiculata L) generally comprises the bushy, short-podded grain cowpea dominant in Africa and the climbing, long-podded vegetable cowpea popular in Asia. How selection has contributed to the diversification of the two types of cowpea remains largely unknown. In the current study, a novel genotyping assay for over 50 000 SNPs was employed to delineate genomic regions governing pod length. Major, minor and epistatic QTLs were identified through QTL mapping. Seventy-two SNPs associated with pod length were detected by genome-wide association studies (GWAS). Population stratification analysis revealed subdivision among a cowpea germplasm collection consisting of 299 accessions, which is consistent with pod length groups. Genomic scan for selective signals suggested that domestication of vegetable cowpea was accompanied by selection of multiple traits including pod length, while the further improvement process was featured by selection of pod length primarily. Pod growth kinetics assay demonstrated that more durable cell proliferation rather than cell elongation or enlargement was the main reason for longer pods. Transcriptomic analysis suggested the involvement of sugar, gibberellin and nutritional signalling in regulation of pod length. This study establishes the basis for map-based cloning of pod length genes in cowpea and for marker-assisted selection of this trait in breeding programmes
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