MXene Based Nanocomposites for Recent Solar Energy Technologies.

This article discusses the design and preparation of a modified MXene-based nanocomposite for increasing the power conversion efficiency and long-term stability of perovskite solar cells. The MXene family of materials among 2D nanomaterials has shown considerable promise in enhancing solar cell performance because of their remarkable surface-enhanced characteristics. Firstly, there are a variety of approaches to making MXene-reinforced composites, from solution mixing to powder metallurgy. In addition, their outstanding features, including high electrical conductivity, Young's modulus, and distinctive shape, make them very advantageous for composite synthesis. In contrast, its excellent chemical stability, electronic conductivity, tunable band gaps, and ion intercalation make it a promising contender for various applications. Photovoltaic devices, which turn sunlight into electricity, are an exciting new area of research for sustainable power. Based on an analysis of recent articles, the hydro-thermal method has been widely used for synthesizing MXene-based nano-composites because of the easiness of fabrication and low cost. Finally, we identify new perspectives for adjusting the performance of MXene for various nanocomposites by controlling the composition of the two-dimensional transition metal MXene phase.

A Brief Review of the Role of 2D Mxene Nanosheets toward Solar Cells Efficiency Improvement.

This article discusses the application of two-dimensional metal MXenes in solar cells (SCs), which has attracted a lot of interest due to their outstanding transparency, metallic electrical conductivity, and mechanical characteristics. In addition, some application examples of MXenes as an electrode, additive, and electron/hole transport layer in perovskite solar cells are described individually, with essential research issues highlighted. Firstly, it is imperative to comprehend the conversion efficiency of solar cells and the difficulties of effectively incorporating metal MXenes into the building blocks of solar cells to improve stability and operational performance. Based on the analysis of new articles, several ideas have been generated to advance the exploration of the potential of MXene in SCs. In addition, research into other relevant MXene suitable in perovskite solar cells (PSCs) is required to enhance the relevant work. Therefore, we identify new perspectives to achieve solar cell power conversion efficiency with an excellent quality-cost ratio.

Association of lipid parameters and insulin resistance with bone health in South Korean adolescents.

UNLABELLED: This study investigated the association between lipid profiles and insulin resistance and bone mineral content (BMC) in Korean adolescents and found that BMC was inversely associated with triglyceride (TG) and homeostasis model assessment of insulin resistance (HOMA-IR). This association did not differ according to obesity status in either boys or girls. INTRODUCTION: To prevent future osteoporosis, it is important to identify factors that affect bone health in adolescents as well as adults. This study aimed to examine the association between lipid profiles and insulin resistance and BMC in Korean adolescents. METHODS: Data from 706 boys and 621 girls, who participated in the Korea National Health and Nutrition Examination Survey from 2008 to 2011, were analyzed. Lipid profiles were measured, and HOMA-IR was calculated to assess insulin resistance. BMC was measured for the total femur, femur neck, and lumbar spine by using whole-body dual-energy X-ray absorptiometry (DXA). RESULTS: TG level and HOMA-IR were negatively correlated with BMC at all three sites in boys. In girls, TG level showed a negative correlation with BMC at the femur neck and lumbar spine, and HOMA-IR was negatively associated with BMC at the femur neck only. These inverse associations did not differ according to obesity status in either sex. Adjusted means of BMC at the three sites in boys tended to decrease in the higher tertile groups of TG and HOMA-IR, and the adjusted means of BMC for the total femur in girls tended to decrease in the higher tertile groups of TG and HOMA-IR. CONCLUSIONS: BMC was inversely associated with TG and HOMA-IR in Korean adolescents, and this association was more pronounced in boys. This association did not differ according to obesity status in either sex.

Ballistocardiogram of baby during sleep.

Ballistocardiogram (BCG), which displays the mechanical activity of heart, has been a subject of interest for several years due to its advantages in taking unobtrusive physiological measurements. In the field of sleep science, researchers actively study sleep architecture and clinically apply various sleep-related conditions through BCG-derived biological information such as the heartbeat, respiration and body movements of subjects. However, most of these studies have involved only adults. This area of research may be even more important with babies to monitor their biological signals without confinement. For this reason, we developed a physiological signal monitoring bed for baby by using a load cell. Heartbeat and respiration information was assessed with average respective performance errors of 1.53% and 2.53% compared to commercial equipment. The results showed the possibility of applying BCG technology to baby. Therefore, we expect that BCG-derived signals can be extensively applied to analyze sleep architecture and clinical applications in baby as they are with adults.

Effect of 0.1% pilocarpine mouthwash on xerostomia: double-blind, randomised controlled trial.

The objective of this study was to evaluate the effect of 0.1% pilocarpine mouthwash in xerostomic patients. Sixty volunteers were randomly allocated to two groups. The experimental group used 0.1% pilocarpine solution, and the control group used 0.9% saline. The short- and long-term effects of pilocarpine were investigated by measuring the severity of oral dryness, minor salivary flow rates and unstimulated whole salivary flow rate at predetermined times. The severity of oral dryness was decreased in both groups at 0, 30 and 60 min after mouthwashing, with no significant difference between the groups. Buccal and labial secretions were increased in both groups, but only the experimental group exhibited increased palatal secretion. Labial and palatal secretions, but not buccal secretion, differed between the groups. The unstimulated whole salivary flow rate was increased in the experimental group and differed from that in the control group. After 4 weeks, the severity of oral dryness was decreased in both groups and did not differ between them. The oral dryness at night or on awakening significantly decreased in both groups, with no significant difference between them, but the oral dryness at other times of the day and the difficulty in swallowing foods were not significantly changed in both groups. Minor salivary and unstimulated whole salivary flow rates did not increase in both groups. Until 1 h after mouthwashing, 0.1% pilocarpine mouthwash increased minor salivary and unstimulated whole salivary secretions, but was not superior compared with 0.9% saline at relieving subjective oral dryness.

Malignant peripheral nerve sheath tumour in the liver of a dog.

A 14-year-old male mixed breed dog was presented for abdominal distension and abdominal pain. Radiographical examination identified a large space-occupying mass in the abdomen. Necropsy examination revealed the presence of a 12cm hepatic mass that occupied almost half of the abdominal cavity. Microscopically, this mass consisted of spindle-shaped neoplastic cells that were arranged in short streams and interlacing bundles. Immunohistochemically, the neoplastic cells expressed vimentin, S-100, protein gene product 9.5 and neuron specific enolase, but were negative for cytokeratin, smooth muscle actin, melan A and von Willebrand Factor. These findings indicated that the hepatic mass was a primary hepatic peripheral nerve sheath tumour. To our knowledge, this is the first documentation of a primary hepatic malignant peripheral nerve sheath tumour in a dog.

Sensory characteristics and consumer acceptability of beef soup with added glutathione and/or MSG.

The sensory characteristics and consumer acceptability of beef soup with added glutathione (GSH) and/or monosodium glutamate (MSG) were investigated to examine the feasibility of GSH as a flavor enhancer. The sensory characteristics of beef soup samples, containing only GSH or MSG at different levels or a mixture of these, were examined by descriptive analysis. Principle component analysis was conducted to summarize the relationships between the beef soup samples and the attributes. In consumer testing, separate groups of consumers evaluated overall liking as well as the flavor intensities of beef, seasoning, and MSG. Partial least square regression was conducted to observe the relationships between the descriptive data and consumer data. The samples containing GSH had stronger "beef flavor,""garlic flavor," and "green onion flavor" while the samples containing MSG had stronger "salty taste,""sweet taste,""MSG taste," and "potato flavor." The consumers preferred samples containing both GSH and MSG, which had higher perceived flavor intensities of beef, seasonings, MSG. This study indicates that GSH has potential as a flavor enhancer, but more tests in different food systems with additions of GSH at varying levels are required to elucidate its effectiveness as a flavor enhancer more clearly.

Impacts of glutathione Maillard reaction products on sensory characteristics and consumer acceptability of beef soup.

The sensory characteristics and consumer acceptability of beef soup with added glutathione Maillard reaction products (GMRPs) were investigated to examine the effects of the GMRPs on beef-soup flavor compared to soups made with glutathione (GSH) and monosodium glutamate (MSG), a control (CON), or a control soup made with 150% beef content (CON150). The sensory characteristics of the beef soups were examined by descriptive analysis. The overall acceptabilities of the beef soups were rated by consumers. Principal component analysis was performed on descriptive data as explanatory variables with overall acceptability as a supplementary variable to observe the relationships between the descriptive data and consumer acceptability, as well as the relationships between the beef-soup samples and their sensory attributes. The samples containing GMRPs had "beef flavor" that was stronger than the CON and MSG samples, and comparable to that of the GSH sample and CON150. The GMRP samples had stronger "green onion flavor,""garlic flavor," and "boiled egg white flavor" than the other samples. The beef soup containing MSG was preferred to CON, CON150, and GSH. The samples with GMRPs were least favored because of their pronounced metallic and astringent notes. The results of this study imply the feasibility of GMRPs as a flavor enhancer since the soups containing these compounds showed more complex flavor profiles than GSH. However, future studies are required to optimize the MR conditions that produce GMRPs without undesirable characteristics. Practical Application: This study examined the practicability of the Maillard reaction products between glutathione (GSH) and glucose (GP) or fructose (FP) as a flavor enhancer by investigating the sensory characteristics and consumer acceptability evoked by them in a beef-soup system. This study helps flavor and food industry to develop a new flavor enhancer by providing practical information, such as beef flavor-enhancing effect of FP and GP compared to that by increasing beef content or adding GSH or MSG. In addition, it is expected that the outcome of this study, such as sensory attributes of and consumer responses to GSH Maillard reaction products, compliments previous studies that mostly focused on chemical analysis of Maillard reaction.

Free fatty acids activate a vigorous Ca(2+):2H(+) antiport activity in yeast mitochondria.

The accumulation and retention of Ca(2+) by yeast mitochondria (Saccharomyces cerevisiae) mediated by ionophore ETH 129 occurs with a variable efficiency in different preparations. Ineffective Ca(2+) transport and a depressed membrane potential occur in parallel, are exacerbated in parallel by exogenous free fatty acids, and are corrected in parallel by the addition of bovine serum albumin. Bovine serum albumin is not required to develop a high membrane potential when either Ca(2+) or ETH 129 are absent, and when both are present membrane potential is restored by the addition of EGTA in a concentration-dependent manner. Respiration and swelling data indicate that the permeability transition pore does not open in yeast mitochondria that are treated with Ca(2+) and ETH 129, whereas fatty acid concentration studies and the inaction of carboxyatractyloside indicate that fatty acid-derived uncoupling does not underlie the other observations. It is concluded that yeast mitochondria contain a previously unrecognized Ca(2+):2H(+) antiporter that is highly active in the presence of free fatty acids and leads to a futile cycle of Ca(2+) accumulation and release when exogenous Ca(2+) and ETH 129 are available. It is also shown that isolated yeast mitochondria degrade their phospholipids at a relatively rapid rate. The activity responsible is also previously unrecognized. It is Ca(2+)-independent, little affected by the presence or absence of a respiratory substrate, and leads to the hydrolysis of ester linkages at both the sn-1 and sn-2 positions of the glycerophospholipids. The products of this activity, through their actions on the antiporter, explain the variable behavior of yeast mitochondria treated with Ca(2+) plus ETH 129.

High-fat diet feeding elevates skeletal muscle uncoupling protein 3 levels but not its activity in rats.

OBJECTIVE: The objective of this study is to test the impact of high-fat diet (HFD) feeding on skeletal muscle (SM) uncoupling protein 3 (UCP3) expression and its association with mitochondrial ion permeability and whole-body energy homeostasis. RESEARCH METHODS AND PROCEDURES: Sprague-Dawley rats were fed ad libitum either a HFD (60% of energy from fat, n = 6) or a low-fat diet (12% of energy from fat, n = 6) for 4 weeks. Twenty-four-hour energy expenditure was measured by indirect calorimetry in the last week of the dietary treatment. Blood samples were collected for plasma leptin and free fatty acid assays, and mitochondria were isolated from hindlimb SM for subsequent determinations of UCP3 levels and mitochondrial ion permeability. RESULTS: Plasma leptin levels were higher in rats fed the HFD despite the same body weight in two groups. The same dietary treatment also rendered a 2-fold increase in plasma free fatty acid and SM UCP3 protein levels (Western blot) compared with the group fed the low-fat diet. However, the elevated UCP3 protein levels did not correlate with mitochondrial swelling rates, a measure of mitochondrial chloride, and proton permeability, or with 24-hour energy expenditure. DISCUSSION: The high correlation between the levels of plasma free fatty acid levels and SM UCP3 suggests that circulating free fatty acid may play an important role in UCP3 expression during the HFD feeding. However, the dissociation between the UCP3 protein levels and 24-hour energy expenditure as well as mitochondrial ion permeability suggests that mitochondrial proton leak mediated by muscle UCP3 may not be a major contributor in energy balance in HFD feeding, and other regulatory mechanisms independent of gene regulation may be responsible for the control of UCP3-mediated uncoupling activity.

Counterion-dye staining method for DNA in agarose gels using crystal violet and methyl orange.

Sensitive and safe methods for visualization of DNA in agarose gels are described. 0.001% crystal violet dissolved in distilled water was used for DNA staining on agarose gels and it could detect as little as 16 ng of DNA (3 kb, pGem-7Zf/EcoRI) without destaining procedure. The detection limit is four times lower than that of ethidium bromide. To improve the sensitivity, we studied a counterion-dye staining method using methyl orange as a counterion-dye which contributes to reduce excessive background staining by crystal violet. Dye concentration, pH of staining solution, mixing molar ratio of two dyes, and staining times were optimized for the counterion-dye staining. By the staining with a mixed solution of 0.0025% crystal violet and 0.0005% methyl orange in distilled water, 8 ng of the 3 kb DNA in an agarose gel was detected within 30 min.

PKC and ERK1/2 regulate amylase promoter activity during differentiation of a salivary gland cell line.

The addition of transforming growth factor alpha (TGFalpha) to a human submandibular gland cell line (HSG) cultured on basement membrane extract Matrigel, synergistically activates the acinar cell-specific salivary amylase promoter. Signaling through beta1 integrins and increased phosphorylation of ERK1/2 are involved in the increased promoter activity. Phorbol-12-myristate-13-acetate (PMA) and thapsigargin increase amylase promoter activity, suggesting that phorbol ester and calcium-dependent protein kinase C (PKC) pathways are also involved. The combination of specific inhibitors of PKC and MEK1 inhibits the amylase promoter. Inhibitors of the calcium-dependent PKC isoforms alpha, beta, and gamma decrease the promoter activity; however, PKCbeta is not detectable in HSG cells. TGFalpha alters the cellular localization of PKCalpha but not -gamma, suggesting PKCalpha is involved in TGFalpha upregulation of the amylase promoter. Furthermore, rottlerin, a PKCdelta-specific inhibitor, increases the promoter activity, suggesting PKC isoforms differentially regulate the amylase promoter. In conclusion, beta1-integrin and TGFalpha signaling pathways regulate the amylase promoter activity in HSG cells. In response to Matrigel and TGFalpha, the activation of both PKCalpha and phosphorylation of ERK1/2 results in synergistic activation of the amylase promoter. Published 2000 Wiley-Liss, Inc.

Matrix free Mg(2+) and the regulation of mitochondrial volume.

Mitochondria must maintain volume homeostasis in order to carry out oxidative phosphorylation. It has been postulated that the concentration of free Mg(2+) ([Mg(2+)]) serves as the sensor of matrix volume and regulates a K(+)-extruding K(+)/H(+) antiport (K. D. Garlid. J. Biol. Chem. 255: 11273-11279, 1980). To test this hypothesis, the fluorescent probe furaptra was used to monitor [Mg(2+)] and free Ca(2+) concentration ([Ca(2+)]) in the matrix of isolated beef heart mitochondria, and K(+)/H(+) antiport activity was measured by passive swelling in potassium acetate. Concentrations that result in 50% inhibition of maximum activity of 92 microM matrix [Mg(2+)] and 2.2 microM [Ca(2+)] were determined for the K(+)/H(+) antiport. Untreated mitochondria average 670 microM matrix [Mg(2+)], a value that would permit <1% of maximum K(+)/H(+) antiport activity. Hypotonic swelling results in large decreases in matrix [Mg(2+)], but swelling due to accumulation of acetate salts does not alter [Mg(2+)]. Swelling in phosphate salts decreases matrix [Mg(2+)], but not to levels that permit appreciable antiport activity. We conclude that 1) it is unlikely that matrix [Mg(2+)] serves as the mitochondrial volume sensor, 2) if K(+)/H(+) antiport functions as a volume control transporter, it is probably regulated by factors other than [Mg(2+)], and 3) alternative mechanisms for mitochondrial volume control should be considered.

Detection of DNA in agarose gels using berberine and Mordant Yellow 3R.

A nontoxic and simple staining method for the detection of DNA in agarose gels is described. After eletrophoretic separation, the gels were stained with 5 microg/ml of berberine (BB) prepared in distilled water and then the gels were soaked in 20 microg/ml of aqueous Mordant Yellow 3R (MY3R) solution. Employment of MY3R as a counterion dye efficiently quenched unwanted background fluorescence of BB. This method can detect as little as 10 ng of plasma membrane H(+)-ATPase cDNA obtained from Arabidopsis thaliana L. (AHA1, 3.2 kb) under a long wavelength of UV irradiation (366 nm) within 1 h.

Mixed-dye staining method for protein detection in polyacrylamide gel electrophoresis using calconcarboxylic acid and rhodamine B.

We have developed a new mixed-dye protein staining method that is simple, rapid, and sensitive. A freshly prepared mixture of calconcarboxylic acid (NN, 0.02%) and rhodamine B (RB, 0.04%) in 40% methanol/7% acetic acid, was used as a staining solution. RB acts as an auxiliary agent to inhibit the binding of NN to the gel matrix, reducing the background staining and therefore enhancing the protein staining by NN. This mixed-dye staining method reduces the total staining and destaining time to less than an hour, and increases the sensitivity to 25 ng of bovine serum albumin, which is greater than the 100 ng sensitivity limit of Coomassie Brilliant Blue R-250 (CBBR) staining.

Laminin-1 and laminin-2 G-domain synthetic peptides bind syndecan-1 and are involved in acinar formation of a human submandibular gland cell line.

The culture of human submandibular gland (HSG) cells on laminin-1 induces acinar differentiation. We identified a site on laminin involved in acinar differentiation using synthetic peptides derived from the C-terminal G-domain of the laminin alpha1 and alpha2 chains. The alpha1 chain peptide AG73 (RKRLQVQLSIRT) decreases the size of acini formed on laminin-1. Cells cultured with either AG73 or the homologous alpha2 chain peptide MG73 (KNRLTIELEVRT) form structures that appear acinar-like, but the cell nuclei are not polarized to the basal surface and no lumen formation occurs, indicating that additional sites on laminin are required for complete differentiation. The G-domain of laminin-1 contains both integrin and heparin binding sites, and anti-beta1-integrin antibodies disrupt acinar formation. Cell adhesion to the peptides and to E3, an elastase digest fragment of laminin-1 containing AG73, is specific, since other laminin peptides or EDTA do not compete the binding. Heparin and heparan sulfate decrease cell adhesion to AG73 and MG73 but anti-beta1-integrin antibodies have no effect. Treating the cell surface with heparitinase inhibits adhesion to both AG73 and MG73. We isolated cell surface ligands using both peptide affinity chromatography and laminin-1 affinity chromatography. Treating the material bound to the affinity columns with heparitinase and chondroitinase enriches for a core protein identified as syndecan-1 by Western blot analysis, thus identifying a syndecan-1 binding site in the globular domain of laminin-1 and laminin-2. In summary, multiple interactions between laminin and HSG cells contribute to acinar differentiation, involving both beta1-integrins and syndecan-1.

ELISA for the determination of saikosaponin a, an active component of Bupleuri Radix.

In order to quantify saikosaponin a (SSA), one of the major active components of Bupleuri Radix, a competitive and indirect ELISA method was developed. High titer rabbit polyclonal antibodies (pAbs) were raised against a conjugate of SSA and bovine serum albumin, coupled with a periodate oxidation method. SSA competitively inhibited the binding of rabbit anti-SSA pAbs to SSA-ovalbumin on the solid phase, a coated antigen on the well. The quantity of pAbs bound to the well was monitored using a peroxidase-conjugated anti-rabbit IgG as a secondary antibody, and tetramethylbenzidine solution as a substrate. The measuring range extended from 50 pg/ml to 20 ng/ml of SSA, with a detection limit of 40 pg/ml (5.13 pM). Antibodies showed some cross-reactivity with saikosaponin c (12.74%). However, the antibodies showed only slight cross-reactivities with saikosaponin d (0.3%), which differs from SSA only in the stereochemistry of the 16-hydroxyl group, and the artificial saikosaponins, saikosaponin b1 (2.1%) and saikosaponin g (0.53%). The specific and sensitive ELISA is especially suited for determination of SSA in samples when only small quantities of materials can be extracted for analysis.

Determination of ginsenoside Rf and Rg2 from Panax ginseng using enzyme immunoassay.

We have developed an enzyme immunoassay (EIA) to quantify trace amounts of ginsenoside Rf (Rf), one of the glycosides of protopanaxatriol from Panax ginseng. A carrier protein of bovine serum albumin (BSA) was coupled to the carbohydrate component of Rf using the periodate oxidation method. Antibodies were raised in rabbits using Rf-BSA conjugate as the immunogen and competitive indirect EIA was used for the determination of Rf. The working range was 0.01-10 ng per assay. The anti-Rf antiserum cross-reacted with ginsenoside Rg2 (105%), which is also a component of Panax ginseng and has a very similar chemical structure to Rf. These results suggest that the anti-Rf antiserum could also be used for the quantitation of ginsenoside Rg2 as well as ginsenoside Rf. In a comparison of EIA and HPLC the linear regression equation and correlation coefficient for the two methods were y(EIA) = 1.31x (HPLC)-11.48 and 0.98, respectively.

Production of antibody against saikosaponin a, an active component of bupleuri radix.

High titer rabbit polyclonal antibodies (pAbs) which show a specificity for saikosaponin a (SSA), have been generated. The immunogen used was a conjugate of SSA linked through its glucose moiety to bovine serum albumin by periodate oxidation method. The antibody titers obtained from two rabbits, inoculated with the immunogen, reached a plateau after the fourth and third booster injection, respectively. The specificity of the pAbs was determined by hapten inhibition assays using several SSA-like structures. SSA competitively inhibited the binding of the rabbit anti-SSA pAbs to SSA-ovalbumin on solid phase, a coated antigen on the well. The antibodies showed high specificity to SSA, exhibiting no significant cross-reactivity with any of SSA analogues tested.