High thermoelectric performance of flexible nanocomposite films based on Bi2Te3 nanoplates and carbon nanotubes selected using ultracentrifugation.

Thermoelectric generators with flexibility and high performance near 300 K have the potential to be employed in self-supporting power supplies for Internet of Things (IoT) devices. Bismuth telluride (Bi2Te3) exhibits high thermoelectric performance, and single-walled carbon nanotubes (SWCNTs) show excellent flexibility. Therefore, composites of Bi2Te3 and SWCNTs should exhibit an optimal structure and high performance. In this study, flexible nanocomposite films based on Bi2Te3 nanoplates and SWCNTs were prepared by drop casting on a flexible sheet, followed by thermal annealing. Bi2Te3 nanoplates were synthesized using the solvothermal method, and SWCNTs were synthesized using the super-growth method. To improve the thermoelectric properties of the SWCNTs, ultracentrifugation with a surfactant was performed to selectively obtain suitable SWCNTs. This process selects thin and long SWCNTs but does not consider the crystallinity, chirality distribution, and diameters. A film consisting of Bi2Te3 nanoplates and the thin and long SWCNTs exhibited high electrical conductivity, which was six times higher than that of a film with SWCNTs obtained without ultracentrifugation; this is because the SWCNTs uniformly connected the surrounding nanoplates. The power factor was 6.3 µW/(cm K2), revealing that this is one of the best-performing flexible nanocomposite films. The findings of this study can support the application of flexible nanocomposite films in thermoelectric generators to provide self-supporting power supplies for IoT devices.

Differences in antimicrobial components between bacterial culture-positive and culture-negative bovine clinical mastitis milk.

A bacterial culture of milk is the most common test to determine the presence of mastitis-causing pathogens, which informs appropriate treatment. However, a certain proportion of clinical mastitis milk shows no growth of any mastitis-causing pathogens. We hypothesized that bacterial culture-negative clinical mastitis milk is associated with the activity of antimicrobial components contained in the milk. In this study, the differences in antimicrobial components (lactoferrin, transferrin, lysozyme, lactoperoxidase, and lingual antimicrobial peptide [LAP]) between bacterial culture-positive and culture-negative bovine clinical mastitis milk were investigated using Holstein cows. Our results showed that 37 out of 71 samples of clinical mastitis milk had negative bacterial cultures. The LAP concentration in bacterial culture-negative milk was lower than that in positive milk (31.95 ± 1.64 nM vs. 42.85 ± 4.01 nM). In contrast, the lysozyme concentration in bacterial culture-negative milk was higher than that in positive milk (0.76 ± 0.15 µg/ml vs. 0.42 ± 0.06 µg/ml). In conclusion, the concentration of antimicrobial components was different between bacterial culture-positive and culture-negative bovine clinical mastitis milk, which suggests that antimicrobial components are related to bacterial culture results.

Heat source free water floating carbon nanotube thermoelectric generators.

Thermoelectric generators (TEGs) produce electric power from environmental heat energy and are expected to play a key role in powering the Internet of things. However, they require a heat source to create a stable and irreversible temperature gradient. Overcoming these restrictions will allow the use of TEGs to proliferate. Therefore, we propose heat source-free water-floating carbon nanotube (CNT) TEGs. Output voltage and power are generated by the temperature gradient in the CNT films in which water pumping via capillary action leads to evaporation-induced cooling in selected areas. Furthermore, the output voltage and power increase when the films are exposed to sunlight and wind flow. These water-floating CNT TEGs demonstrate a pathway for developing wireless monitoring systems for water environments.

Origin of n type properties in single wall carbon nanotube films with anionic surfactants investigated by experimental and theoretical analyses.

We investigated the origin of n-type thermoelectric properties in single-wall carbon nanotube (SWCNT) films with anionic surfactants via experimental analyses and first-principles calculations. Several types of anionic surfactants were employed to fabricate SWCNT films via drop-casting, followed by heat treatment at various temperatures. In particular, SWCNT films with sodium dodecylbenzene sulfonate (SDBS) surfactant heated to 350 °C exhibited a longer retention period, wherein the n-type Seebeck coefficient lasted for a maximum of 35 days. In x-ray photoelectron spectroscopy, SWCNT films with SDBS surfactant exhibited a larger amount of sodium than oxygen on the SWCNT surface. The electronic band structure and density of states of SWCNTs with oxygen atoms, oxygen molecules, water molecules, sulfur atoms, and sodium atoms were analyzed using first-principles calculations. The calculations showed that sodium atoms and oxygen molecules moved the Fermi level closer to the conduction and valence bands, respectively. The water molecules, oxygen, and sulfur atoms did not affect the Fermi level. Therefore, SWCNT films exhibited n-type thermoelectric properties when the interaction between the sodium atoms and the SWCNTs was larger than that between the oxygen molecules and the SWCNTs.

Picosecond pulsed infrared laser tuned to amide I band dissociates polyglutamine fibrils in cells.

Amyloid fibrils are causal substances for serious neurodegenerative disorders and amyloidosis. Among them, polyglutamine fibrils seen in multiple polyglutamine diseases are toxic to neurons. Although much efforts have been made to explore the treatments of polyglutamine diseases, there are no effective drugs to block progression of the diseases. We recently found that a free electron laser (FEL), which has an oscillation wavelength at the amide I band (C = O stretch vibration mode) and picosecond pulse width, was effective for conversion of the fibril forms of insulin, lysozyme, and calcitonin peptide into their monomer forms. However, it is not known if that is also the case in polyglutamine fibrils in cells. We found in this study that the fibril-specific ß-sheet conformation of polyglutamine peptide was converted into nonfibril form, as evidenced by the infrared microscopy and scanning-electron microscopy after the irradiation tuned to 6.08 µm. Furthermore, irradiation at this wavelength also changed polyglutamine fibrils to their nonfibril state in cultured cells, as shown by infrared mapping image of protein secondary structure. Notably, infrared thermography analysis showed that temperature increase of the cells during the irradiation was within 1 K, excluding thermal damage of cells. These results indicate that the picosecond pulsed infrared laser can safely reduce amyloid fibril structure to the nonfibril form even in cells.

Reliability in somatic cell count measurement of clinical mastitis milk using DeLaval cell counter.

Somatic cell counts (SCC) measurements are typically performed using quantitative methods, such as the Breed method (Breed) and the Fossomatic method (FSCC). The DeLaval cell counter (DCC) developed recently is a quantitative somatic cell counter with a low initial cost and superior portability. However, since the DCC was specifically developed for measuring SCC of ≤ 4 × 10(6) cells/mL milk from bulk tanks or individual cows, its reliability for estimating SCC that exceed this concentration has not yet been clarified. This study therefore examined whether it is possible to accurately measure SCC by diluting milk samples with initial SCC of 4 × 10(6) cells/mL, as seen in clinical mastitis milk. We collected milk samples from 99 quarters of 99 Holstein cows with clinical mastitis. These milk samples were diluted 10-fold with saline and thoroughly mixed before performing SCC measurement with the DCC. The correlation coefficients of SCC measured by the FSCC, Breed and DCC methods indicated strong correlations between each pair of methods. The findings showed that DCC can be used to identify bovine clinical mastitis milk and is useful as a quantitative SCC measurement device on farm sites.

Octanoate reduces very low-density lipoprotein secretion by decreasing the synthesis of apolipoprotein B in primary cultures of chicken hepatocytes.

Fatty acids of varying lengths and saturation differentially affect plasma apolipoprotein B (apoB) levels. To identify the mechanisms underlying the effect of octanoate on very low-density lipoprotein (VLDL) secretion, chicken primary hepatocytes were incubated with either fatty acid-bovine serum albumin (BSA) complexes or BSA alone. Addition of octanoate to culture medium significantly reduced VLDL-triacylglycerol (TG), VLDL-cholesterol and apoB secretion from hepatocytes compared to both control cultures with BSA only and palmitate treatments, but did not modulate intracellular TG accumulation. However, no differences in cellular microsomal triglyceride transfer protein levels were observed in the cultures with saturated fatty acid. In pulse-chase studies, octanoate treatment resulted in reduced apoB-100 synthesis, in agreement with its promotion of secretion. This characteristic effect of octanoate was confirmed by addition of a protease inhibitor, N-acetyl-leucyl-leucyl-norleucinal (ALLN), to hepatocyte cultures. Analysis showed that the level of apoB mRNA was lower in cultures supplemented with octanoate than in the control cultures, but no significant changes were observed in the levels of apolipoprotein A-I, fatty acid synthase and 3-hydroxy-3-methylglutaryl-CoA reductase mRNA as a result of octanoate treatment. Time-course studies indicate that a 50% reduction in apoB mRNA levels requires 12 h of incubation with octanoate. We conclude that octanoate reduced VLDL secretion by the specific down-regulation of apoB gene expression and impairment of subsequent synthesis of apoB, not by the modulation of intracellular apoB degradation, which is known to be a major regulatory target of VLDL secretion of other fatty acids.

Impairment of VLDL secretion by medium-chain fatty acids in chicken primary hepatocytes is affected by the chain length.

To determine the effect of the chain length of medium-chain fatty acids (MCFAs) on VLDL secretion, the media of chicken hepatocyte cultures were supplemented with hexanoate (6:0), octanoate (8:0), decanoate (10:0), or dodecanoate (12:0). The supplementation of palmitate (16:0) or bovine serum albumin (BSA) alone in media was used as the positive control or the control, respectively. Palmitate significantly increased intracellular triacylglycerol (TG) accumulation and VLDL-TG, -cholesterol, and -apolipoprotein (apo)B secretion. On the other hand, the addition of hexanoate did not affect these variables relative to control cultures supplemented with BSA alone, whereas octanoate, decanoate, and dodecanoate decreased apoB secretion from the chicken hepatocytes. ApoB secretion from hepatocytes cultured with 1.0 mmol/L MCFA, in particular decanoate and dodecanoate, in the presence of 0.2 mmol/L palmitate was significantly lower than that obtained with 0.2 mmol/L palmitate alone. Decanoate at 0.25-1.0 mmol/L dose dependently reduced apoB mRNA expression compared with the control (BSA alone). The levels of 3-hydroxy-3-metylglutaryl-CoA reductase and apoA-I mRNA were significantly lower in cultures supplemented with hexanoate, octanoate, and decanoate than in cultures with dodecanoate and palmitate. These changes did not correspond to the reduction in VLDL-apoB secretion. We suggest that MCFAs with different chain lengths differentially affect apoB secretion and mRNA expression, with decanoate being the most effective at decreasing VLDL-apoB secretion by regulating apoB mRNA expression at the transcriptional level.