General strategy for developing thick-film micro-thermoelectric coolers from material fabrication to device integration.

Micro-thermoelectric coolers are emerging as a promising solution for high-density cooling applications in confined spaces. Unlike thin-film micro-thermoelectric coolers with high cooling flux at the expense of cooling temperature difference due to very short thermoelectric legs, thick-film micro-thermoelectric coolers can achieve better comprehensive cooling performance. However, they still face significant challenges in both material preparation and device integration. Herein, we propose a design strategy which combines Bi2Te3-based thick film prepared by powder direct molding with micro-thermoelectric cooler integrated via phase-change batch transfer. Accurate thickness control and relatively high thermoelectric performance can be achieved for the thick film, and the high-density-integrated thick-film micro-thermoelectric cooler exhibits excellent performance with maximum cooling temperature difference of 40.6 K and maximum cooling flux of 56.5 W·cm-2 at room temperature. The micro-thermoelectric cooler also shows high temperature control accuracy (0.01 K) and reliability (over 30000 cooling cycles). Moreover, the device demonstrates remarkable capacity in power generation with normalized power density up to 214.0 µW · cm-2 · K-2. This study provides a general and scalable route for developing high-performance thick-film micro-thermoelectric cooler, benefiting widespread applications in thermal management of microsystems.

Association of waist-calf circumference ratio, waist circumference, calf circumference, and body mass index with all-cause and cause-specific mortality in older adults: a cohort study.

BACKGROUND: Waist circumference (WC), calf circumference (CC), and body mass index (BMI) have been independently linked to mortality. However, it's not yet clear how the waist-calf circumference ratio (WCR) relates to mortality. This study aims to investigate the relationship between WCR, WC, CC, and BMI with all-cause and cause-specific mortality in older adults. METHODS: In the 2014 Chinese Longitudinal Healthy Longevity Survey, 4627 participants aged 65 years and older were included, and they were subsequently followed up in 2018. Cox proportional hazards models were utilized to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality, based on WCR, WC, CC, and BMI. RESULTS: During a median follow-up of 3.4 years, 1671 deaths (36.1%) occurred. Compared to the second quartile of WCR, the highest quartile had a higher risk of mortality from all causes (HR 1.42, 95%CI 1.24-1.64), cardiovascular disease (CVD) (HR 1.88, 95%CI 1.38-2.56), and other causes (HR 1.37, 95%CI 1.15-1.63). The first and fourth quartiles of WC had HRs of 2.19 (1.00-4.79) and 2.69 (1.23-5.89), respectively, for cancer mortality. The highest quartile of CC was associated with a lower risk of all-cause and other-cause mortality, whereas the lowest quartile was associated with a higher risk of all-cause, CVD, and other-cause mortality compared to the second CC quartile. Additionally, the lowest quartile of BMI was associated with a higher risk of all-cause and respiratory disease mortality. Interaction analyses showed that the effects of CC on all-cause and CVD mortality were more pronounced in adults aged ≥ 80 years (P-interaction < .05). CONCLUSIONS: Higher WCR and lower CC increased the risk of all-cause, CVD, and other-cause mortality. Lower BMI was associated with higher all-cause and respiratory disease mortality risk, while WC only predicted cancer mortality.

Dual-Ion Electrochemical Deionization System with Binder-Free Aerogel Electrodes.

Desalination devices such as capacitive deionization (CDI) have been developed for many years as an approach to relief freshwater shortage. However, due to the limitation of physical adsorption capacity of CDI, the salt removal capacity is unable to reach high value. To enhance the desalination capacity effectively, battery materials are employed to fabricate a dual-ion electrochemical deionization (DEDI) device. Herein, a binder-free DEDI system with two free-standing aerogel electrodes is reported. A Na3 V2 (PO4 )3 /graphene hybrid aerogel is used as sodium electrode and a AgCl/graphene hybrid aerogel is used as chloride electrode. With electric current passing through, sodium and chloride ions are released or absorbed by two aerogel electrodes. This system achieves super high desalination capacity, excellent cycling stability, and rapid desalination rate. The desalination capacity is as high as 107.5 mg g-1 after 50 cycles with the current density of 100 mA g-1 . The outstanding desalination performance of this system shows a synergistic effect of combining battery materials with graphene for deionization and promises a new potential alternative of future desalination design.

Ultrahigh-Desalination-Capacity Dual-Ion Electrochemical Deionization Device Based on Na3V2(PO4)3@C-AgCl Electrodes.

Seawater desalination is a promising way to alleviate water scarcity nowadays. Present capacitive desalination methods have limitation of salt removal capacity. Herein, a new dual-ion electrochemical desalination system with an ultrahigh desalination capacity is reported. It is composed of Na3V2(PO4)3@C wires as a sodium ion Faradaic electrode, AgCl as a chloride ion Faradaic electrode, and salt feed solution as the electrolyte. When a constant current is applied, redox reactions occur on electrodes, releasing or removing sodium ions and chloride ions. Na3V2(PO4)3 has a high sodium specific capacity, and as a sodium superionic conductor, Na3V2(PO4)3@C wires form an ion conductor network, providing high sodium ion mobility. Additionally, both the wire structure and carbon shell enhance the electrical conductivity of Na3V2(PO4)3. Benefiting from these, outstanding desalination performance, rate capability, and cycle capability have been achieved with the Na3V2(PO4)3@C wire-AgCl device. An ultrahigh desalination capacity of 98.0 mg/g is obtained at a current density of 100 mA/g for more than 50 cycles. This system provides a viable dual-ion electrochemical desalination strategy, which outperforms most of the existing desalination methods.

The prevalence and adverse profiles of fatty liver disease among different ethnic public servants in Urumqi of Xinjiang Uygur Autonomous Region in China.

BACKGROUND: The purpose of this survey was to confirm the prevalence and adverse profiles of fatty liver disease among different ethnic public servants in Urumqi of Xinjiang. METHODS: The cross-sectional study were implemented among serving and retired public servants who participated in the annual physical check-up including abdominal ultrasonography from April 2012 to April 2013 at the health promotion center of the First Affiliated Hospital of Xinjiang Medical University in Urumqi. The information including questionnaires, anthropometric indexes and biochemical profiles were collected to analyze. RESULTS: There were 46612 individuals ranging from 20 to 93 years of age included in the analysis. There were 39120 of Han, 4148 of Uygur, 877 of Kazakh, 2098 of Hui, and 369 of other ethnic groups. The prevalence of FLD in total, Han, Hui, Uygur, Kazakh and other ethnic group were 32.0%, 31.2%, 31.5%, 39.3%, 36.4% and 32.8%. Uygur was significantly higher than the other ethnic groups both male and female (P < 0.01) and male was higher than female regardless of ethnicity (P < 0.01). FLD co-exiting with DM, hypertension, obesity, overweight and dysliplidemia (especially for hypertriglyceridemia) were common and distribution of these diseases were significantly different among various ethnicity (P < 0.01). Multiple logistic regression analysis indicated that there were different in adverse factors including age, gender, DM, obesity, dyslipidemia and hypertension of FLD among ethnicity and obesity having higher OR value in each ethnic group can be as predictive index of FLD. CONCLUSIONS: The high prevalence of FLD is present among public servants in Urumqi of Xinjiang, China. The prevalence of FLD is significantly different in different ethnic groups and genders. Distributions of adverse factors are disparate in different ethnicity. Comprehensive strategies for the prevention and treatment of FLD should be explored basing on the ethnic differences.

Ethnic differences in acylation stimulating protein (ASP) in Xinjiang Uygur autonomous region, China.

BACKGROUND: Acylation Stimulating Protein (ASP) stimulates adipocyte triglyceride synthesis and glucose transport. The aim was to examine ethnic difference in ASP and the relation to lipid profile and other parameters among Han, Uygur, and Kazak healthy populations matched for BMI, age and gender distribution. METHODS: 331 healthy persons were recruited in total (age 30-60 yr): 137 Han, 114 Uygur, and 80 Kazak. Anthropometric measurements including height, weight, waist circumference, hip circumference, blood pressure, ankle brachial index (ABI), and pulse wave velocity (PWV) were measured in all participants. Fasting concentrations of fasting glucose, uric acid, and lipids, including triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), ASP, complement C3, insulin, non-esterified fatty acid (NEFA) and C-reactive protein (CRP) were measured. RESULTS: ASP in Uygurs was significantly lower than Han subjects (P=0.0003). The Uygurs demonstrated the highest C3 (P<0.001), CRP (P=0.001), and NEFA concentrations (P=0.008), the lowest %ASP/C3 (P<0.001) and TC levels (P=0.0008) vs those in Han and Kazak populations. In the Han group, glucose, the average ABI (an index of peripheral response) and diastolic blood pressure were significantly different from both Uygur and Kazak group (P=0.0007, P=0.0003, P=0.0001) while Kazaks show the lowest waist/hip circumference (WHR) (P=0.0003). CONCLUSION: There are ethnic differences in ASP, C3, CRP and lipid profiles in healthy Han, Uygur, and Kazak populations. Overall, the Uygur populations presents with a disadvantageous metabolic profile as compared to Han and Kazak groups.

n-Type carbon nanotubes/silver telluride nanohybrid buckypaper with a high-thermoelectric figure of merit.

n-Type thermoelectric (TE) materials was made from carbon nanotube (CNT) buckypapers. We used silver telluride (Ag2Te) to achieve electron injection to the CNTs. The TE characterizations on more than 50 samples show that the CNTs/Ag2Te hybrids exhibit negative Seebeck coefficients (e.g., n-type) from -30 to -228 µV/K. Meanwhile, the tunneling coupling between the CNTs and Ag2Te increase the electrical conductance to the range of 10,000-20,000 S/m, which is higher than each single component (CNTs or Ag2Te). These n-type TE buckypapers are flexible and robust with ZT values of 1-2 orders of magnitude higher than previously reproted for CNT-based TE materials. In addition, the preparation of such buckypapers are very simple compared to a tranditonal inorganic process, without the need for hot pressing or spark sintering. These n-type TE buckypapers can provide important components for fabricating CNT-based flexible TE devices with good conversion efficiency.

A carbon monoxide gas sensor using oxygen plasma modified carbon nanotubes.

Carbon monoxide (CO) is a highly toxic gas that can be commonly found in many places. However, it is not easily detected by human olfaction due to its colorless and odorless nature. Therefore, highly sensitive sensors need to be developed for this purpose. Carbon nanotubes (CNTs) have an immense potential in gas sensing. However, CNT-based gas sensors for sensing CO are seldom reported due to the lack of reactivity between CO and CNTs. In this work, O(2) plasma modified CNT was used to fabricate a CNT gas sensor. The plasma treated CNTs showed selectively towards CO, with the capability of sensing low concentrations of CO (5 ppm) at room temperature, while the pristine CNTs showed no response. UV spectra and oxygen reduction reaction provided evidence that the difference in sensing property was due to the elimination of metallic CNTs and enhancement of the oxygen reduction property.

Preparation and thermoelectric properties of sulfur doped Ag2Te nanoparticles via solvothermal methods.

In this work, n-type Ag(2)Te nanoparticles are prepared by a solvothermal approach with uniform and controllable sizes, e.g. 5-15 nm. The usage of dodecanethiol during the synthesis effectively introduces sulfur doping into the sample, which optimizes the charge carrier concentration of the nanoparticles to >1 × 10(20) cm(-3). This allows us to achieve the desired electrical resistivities of <5 × 10(-6)Ω m. It is demonstrated that Ag(2)Te particles prepared by this solvothermal process can exhibit high ZT values, e.g. 15 nm Ag(2)Te nanoparticles with effective sulphur doping show a maximum ZT value of ~0.62 at 550 K.

High-power and high-energy-density flexible pseudocapacitor electrodes made from porous CuO nanobelts and single-walled carbon nanotubes.

We report a simple wet-chemical process to prepare porous CuO nanobelts (NBs) with high surface area and small crystal grains. These CuO NBs were mixed with carbon nanotubes in an appropriate ratio to fabricate pseudocapacitor electrodes with stable cycling performances, which showed a series of high energy densities at different power densities, for example, 130.2, 92, 44, 25, and 20.8 W h kg(-1) at power densities of 1.25, 6.25, 25, and 50 k Wh kg(-1), respectively. CuO-on-single-walled carbon nanotube (SWCNT) flexible hybrid electrodes were also fabricated using the SWCNT films as current collectors. These flexible electrodes showed much higher specific capacitance than that of electrodes made of pure SWCNTs and exhibited more stable cycling performance, for example, effective specific capacitances of >62 F g(-1) for the hybrid electrodes after 1000 cycles in 1 M LiPF6/EC:DEC at a current density of 5 A g(-1) and specific capacitance of only 23.6 F g(-1) for pure SWCNT electrodes under the same testing condition.