Expanded graphite (EG) powder as a typical porous material has high thermal conductivity and large surface area that are often used to enhance the thermal conductivity of phase change materials ...(PCMs). Ten composites of paraffin/EG powder with various weight fractions were elaborated by high pressure compression. Their microstructure configuration and thermal properties were characterized with Scanning Electron Microscopy (SEM), Thermal Constant Analyzer. The saturation sorption capacity of EG under compression was experimentally determined. The thermal conductivity of the paraffin/EG composite is greatly enhanced by 41 times in maximum as compared to pure paraffin. Based on the experimental quantification, we propose a novel two-level scale model from micro-scale to macro-scale to compute the thermal conductivity of the composite. The numerical results agree well with the experimental data that validate the precision and reliability of the proposed model. Furthermore, the results reveal that both keeping porous EG structure at original morphology and increasing the saturated sorption capacity of paraffin in EG could eventually improve the heat transfer capacity of the composites. In addition, the proposed model would require more experimental validation based on the composites with different materials in future work.
•Ten paraffin/EG composites were elaborated with high pressure compression.•The saturation sorption capacity of composites was experimentally determined.•The composite thermal conductivity is greatly enhanced by 41 times as compared to pure paraffin.•We propose a two-level scale model to compute the thermal conductivity.•The simulation results have been validated by experiment.
A novel palmitic acid @ZnO/Expanded graphite composite phase change material (PCM) was prepared. Palmitic acid (PA) was selected as phase change material and ZnO/Expanded Graphite as supporting ...material. Expanded graphite (EG), which was used to improve the thermal conductivity of PCM, was chemically modified using ZnO derived from ZIF-8. ZnO derived from ZIF-8 has abundant pore structure and large specific surface area. The structure of ZnO/EG additive was characterized by SEM analyzing method. The prepared ZnO/EG has a three-dimensional coupled network and hierarchical porous structure. Meanwhile, EG can effectively prevent the structural collapse and aggregation of Metal-Organic Framework (MOF) derivatives. The morphology and thermal properties of composite PCMs were analyzed with SEM, XRD, FTIR, DSC, TG, and DTG. The melting/solidifying temperatures and corresponding latent heats of composite PCM PA@ZnO/EG-6% are 60.38 °C and 58.46 °C, and 203.35 kJ/kg and 207.87 kJ/kg. Thermal conductivity of the composite PCM PA@ZnO/EG-6% increases by 137.5% than that of PA. The DTG results indicated the composite PCM has superior thermal stability. All test results suggested that this composite is a good PCM and has excellent potential in heat storage due to its excellent thermal properties, good thermal stability, and reliability.
•The expanded graphite was modified by ZnO in situ precipitation method.•The prepared ZnO/EG has the three-dimensional coupled network.•The melting phase change enthalpy of the composite PCMs could attain 203.35 kJ/kg.•The thermal conductivity of PCM with 6 wt% ZnO/EG increases by 137.5% than that of PA.
Aim To investigate the feasibility of assessing vertebral marrow adipose tissue using a magnetic resonance imaging (MRI) chemical shift-based water–fat separation technique at 3 T. Material and ...methods A modified Dixon technique was performed to obtain the vertebral marrow fat fraction (FF) in a study of 58 postmenopausal females (age range 49.2–77.4 years), including 24 normal bone density, 19 osteopaenia, and 15 osteoporosis as documented with dual-energy X-ray absorptiometry. The reliability of FF measurements performed by two radiologists independently was evaluated with the intraclass correlation coefficient (ICC). Ten participants were scanned twice to assess the reproducibility of FF measurements. FF values were compared between each vertebral level and between groups. Results The mean coefficient of variation of FF measurements was 2.1%. According to the ICC, the measurements were reliable (ICC = 0.900 for normal bone density, ICC = 0.937 for osteopaenia and ICC = 0.909 for osteoporosis, p < 0.001 for all). There was an inverse association between mean FF at L1–L4 vertebrae and lumbar spine BMD ( r = −0.459, p = 0.006), which remained significant even after controlling for confounders (age, height, and body weight). FF values at different vertebral levels were significantly correlated to each other ( r = 0.703–0.921, p < 0.05 for all). There was a general trend toward increased marrow adiposity for more inferior vertebral bodies. Patients with osteopaenia and osteoporosis had a higher marrow fat content compared with normal bone mass after adjusting for confounders, although no significant differences in each vertebral level and average marrow fat content were found between the osteopaenia and osteoporosis groups. Conclusion Chemical shift-based water–fat separation enables the quantitation of vertebral marrow adiposity with excellent reproducibility, which appears to be a useful method to provide complementary information to osteoporosis-related research fields.
Summary
The aim of this study was to evaluate the oxidative status in ketotic cows. We observed changes in the oxidative status and correlations between the oxidative and metabolic status in ...non‐ketotic (n = 10), subclinical ketotic (n = 10) and ketotic cows (n = 10). Plasma samples were analysed by standard biochemical techniques and ELISA to determine traditional metabolic parameters: triglyceride (TG), phosphonium (P), calcium (Ca), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total protein (TP), albumin (ALB), immune globulin (Ig), total cholesterol (TC), high‐density lipoprotein (HDL), very low‐density lipoprotein (VLDL) and lactate dehydrogenase (LDH); energy metabolism indices: glucose, β‐hydroxybutyrate (BHBA) and non‐esterified fatty acids (NEFA); and indices of oxidative status: malondialdehyde (MDA), hydrogen peroxide (H2O2), vitamin C, vitamin E, superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), catalase (CAT), xanthine oxidase (XOD) and total antioxidant capacity (TAOC). The results of this study showed that plasma glucose levels were lower in ketotic and subclinical ketotic cows than in non‐ketotic cows; however, the plasma NEFA and BHBA concentrations were higher. In addition, significant decreases in TC, HDL and VLDL and significant increases in AST, ALT and LDH were observed in the plasma of the ketotic cows. The ketotic cows showed decreased plasma SOD, CAT, vitamin C and vitamin E, inhibited hydroxyl radical capacity and increased plasma H2O2 and MDA. There were positive correlations between the plasma NEFA and ALT, AST, LDH and MDA and negative correlations between the plasma NEFA and TC, HDL, VLDL, SOD, vitamin C, vitamin E, 1542280 uric acid and inhibited hydroxyl radical capacity. In addition, there were positive correlations between BHBA concentrations and ALT, AST and LDH and negative correlations between plasma BHBA concentrations and TC, HDL, VLDL, vitamin E and inhibited hydroxyl radical capacity. Overall, ketotic dairy cows experience oxidative stress, which is presumably associated with hyperketonemia and higher NEFA.
A novel Ralstonia Bcul-1 strain was isolated from soil samples that was closest to Ralstonia pickettii. Broad-spectrum resistance was identified to a group of heavy metal ions and tolerance to ...concentrations of Cd2+ up to 400 mg L-1. Low concentrations of heavy metal ions did not have distinctive impact on heavy metal resistance genes and appeared to induce greater expression. Under exposure to Cd2+, cell wall components were significantly enhanced, and some proteins were also simultaneously expressed allowing the bacteria to adapt to the high Cd2+ living environment. The maximum removal rate of Cd2+ by the Ralstonia Bcul-1 strain was 78.97% in the culture medium supplemented with 100 mg L-1 Cd2+. Ralstonia Bcul-1 was able to survive and grow in a low nutrient and cadmium contaminated (0.42 mg kg-1) vegetable soil, and the cadmium removal rate was up to 65.76% in 9th growth. Ralstonia Bcul-1 mixed with biochar could maintain sustainable growth of this strain in the soil up to 75 d and the adsorption efficiency of cadmium increased by 16.23–40.80% as compared to biochar application alone. Results from this work suggests that Ralstonia Bcul-1 is an ideal candidate for bioremediation of nutrient deficient heavy metal contaminated soil.
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•A novel Ralstonia was identified by genes and phenotypic characteristics.•Few studies on Ralstonia bioremediation to the soil contaminated by heavy metals.•Ralstonia Bcul-1 has broad-spectrum resistance to heavy metal ions, which is regulated by heavy metal-resistant genes.•Cell wall components change and protein expression to adapt to the living environment under the action of Cd2+.•The mixture of Ralstonia Bcul-1 and biochar show excellent practice application prospect to adsorb cadmium in low nutrition soil.
Modulation of pore environment is an effective strategy to optimize guest binding in porous materials. We report the post-synthetic modification of the charge distribution in a charged metal-organic ...framework, MFM-305-CH
, Al(OH)(L)Cl, (H
L)Cl = 3,5-dicarboxy-1-methylpyridinium chloride and its effect on guest binding. MFM-305-CH
shows a distribution of cationic (methylpyridinium) and anionic (chloride) centers and can be modified to release free pyridyl N-centres by thermal demethylation of the 1-methylpyridinium moiety to give the neutral isostructural MFM-305. This leads simultaneously to enhanced adsorption capacities and selectivities (two parameters that often change in opposite directions) for CO
and SO
in MFM-305. The host-guest binding has been comprehensively investigated by
synchrotron X-ray and neutron powder diffraction, inelastic neutron scattering, synchrotron infrared and
H NMR spectroscopy and theoretical modelling to reveal the binding domains of CO
and SO
in these materials. CO
and SO
binding in MFM-305-CH
is shown to occur
hydrogen bonding to the methyl and aromatic-CH groups, with a long range interaction to chloride for CO
. In MFM-305 the hydroxyl, pyridyl and aromatic C-H groups bind CO
and SO
more effectively
hydrogen bonds and dipole interactions. Post-synthetic modification
dealkylation of the as-synthesised metal-organic framework is a powerful route to the synthesis of materials incorporating active polar groups that cannot be prepared directly.
Topological nodal-line semimetals with exotic quantum properties are characterized by symmetry-protected line-contact bulk band crossings in the momentum space. However, in most of identified ...topological nodal-line compounds, these topological nontrivial nodal lines are enclosed by complicated topological trivial states at the Fermi energy (EF), which would perplex their identification and hinder further applications. Utilizing angle-resolved photoemission spectroscopy and first-principles calculations, we provide compelling evidence for the existence of Dirac nodal-line fermions in the monoclinic semimetal SrAs3, which possesses a simple nodal loop in the vicinity of EF without the distraction from complicated trivial Fermi surfaces. Our calculations revealed that two bands with opposite parities were inverted around Y near EF, resulting in the single nodal loop at the Γ−Y−S plane with a negligible spin-orbit coupling effect. The band crossings were tracked experimentally and the complete nodal loop was identified quantitatively, which provide a critical experimental support for the existence of nodal-line fermions in the CaP3 family of materials. Hosting simple topological nontrivial bulk electronic states around EF and without complication from the trivial states, SrAs3 is expected to be a potential platform for topological quantum state investigation and applications.
Background and aims:The major risk factors for acute hepatitis B (AHB) in China and the viral factors determining the progression from acute to chronic hepatitis B remain largely ...unknown.Methods:Epidemiological studies within a population-based surveillance for AHB in adults were performed in Shanghai, China, including 294 patients, 588 matched controls and 572 family members of the patients.Results:Invasive medical procedures, household contact with hepatitis B virus (HBV) carriers, body care and beauty treatments, and lack of HBV vaccination were independently associated with AHB. Among those risks, pedicure in bath centres emerged. Sixty-eight of 128 patients with AHB were genotyped including 33 with HBV B2 and 35 with HBV C2. Twenty-five (8.50%) of the 294 patients, including 20 with HBV C2 and 5 with HBV B2 (p = 0.013), progressed to chronic infection. Multivariate analysis showed that HBV C2 was independently associated with chronicification of AHB. Patients with HBV B2 were younger and there was a higher proportion of women than those with HBV C2. The prevalence of HBV B2 was higher in the patients than in neighbourhood chronic carriers. The chronic carriers with HBV B2 showed higher viral loads, higher hepatitis B e antigen (HBeAg) seropositivity, and with higher proportion in men than those with HBV C2, implying that sexual contact plays a role in the transmission of HBV B2. Phylogenetic analysis showed that HBV C2 was frequently involved in transmissions within households.Conclusions:Despite lower viral load and HBeAg status in the chronic carriers, HBV C2 was more prone to causing chronic infection than was HBV B2.
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