Tet-mediated DNA demethylation regulates specification of hematopoietic stem and progenitor cells during mammalian embryogenesis.

Ten-eleven translocation (Tet) enzymes promote DNA demethylation by oxidizing 5-methylcytosine. They are expressed during development and are essential for mouse gastrulation. However, their postgastrulation functions are not well established. We find that global or endothelial-specific loss of all three Tet enzymes immediately after gastrulation leads to reduced number of hematopoietic stem and progenitor cells (HSPCs) and lethality in mid-gestation mouse embryos. This is due to defects in specification of HSPCs from endothelial cells (ECs) that compromise primitive and definitive hematopoiesis. Mechanistically, loss of Tet enzymes in ECs led to hypermethylation and down-regulation of NFκB1 and master hematopoietic transcription factors (Gata1/2, Runx1, and Gfi1b). Restoring Tet catalytic activity or overexpression of these factors in Tet-deficient ECs rescued hematopoiesis defects. This establishes Tet enzymes as activators of hematopoiesis programs in ECs for specification of HSPCs during embryogenesis, which is distinct from their roles in adult hematopoiesis, with implications in deriving HSPCs from pluripotent cells.

The DNA dioxygenase Tet1 regulates H3K27 modification and embryonic stem cell biology independent of its catalytic activity.

Tet enzymes (Tet1/2/3) oxidize 5-methylcytosine to promote DNA demethylation and partner with chromatin modifiers to regulate gene expression. Tet1 is highly expressed in embryonic stem cells (ESCs), but its enzymatic and non-enzymatic roles in gene regulation are not dissected. We have generated Tet1 catalytically inactive (Tet1m/m) and knockout (Tet1-/-) ESCs and mice to study these functions. Loss of Tet1, but not loss of its catalytic activity, caused aberrant upregulation of bivalent (H3K4me3+; H3K27me3+) developmental genes, leading to defects in differentiation. Wild-type and catalytic-mutant Tet1 occupied similar genomic loci which overlapped with H3K27 tri-methyltransferase PRC2 and the deacetylase complex Sin3a at promoters of bivalent genes and with the helicase Chd4 at active genes. Loss of Tet1, but not loss of its catalytic activity, impaired enrichment of PRC2 and Sin3a at bivalent promoters leading to reduced H3K27 trimethylation and deacetylation, respectively, in absence of any changes in DNA methylation. Tet1-/-, but not Tet1m/m, embryos expressed higher levels of Gata6 and were developmentally delayed. Thus, the critical functions of Tet1 in ESCs and early development are mediated through its non-catalytic roles in regulating H3K27 modifications to silence developmental genes, and are more important than its catalytic functions in DNA demethylation.

Cannabis Use and the Onset of Cigarette and E-cigarette Use: A Prospective, Longitudinal Study Among Youth in the United States.

INTRODUCTION: Cigarette use is declining among youth in the United States, whereas cannabis use and e-cigarette use are increasing. Cannabis use has been linked with increased uptake and persistence of cigarette smoking among adults. The goal of this study was to examine whether cannabis use is associated with the prevalence and incidence of cigarette, e-cigarette, and dual product use among U.S. youth. METHODS: Data included U.S. youth ages 12-17 from two waves of the Population Assessment of Tobacco and Health (PATH) Study (Wave 1 youth, n = 13 651; Wave 1 tobacco-naive youth, n = 10 081). Weighted logistic regression models were used to examine the association between Wave 1 cannabis use and (1) Wave 1 prevalence of cigarette/e-cigarette use among Wave 1 youth and (2) Wave 2 incidence of cigarette/e-cigarette use among Wave 1 tobacco-naive youth. Analyses were run unadjusted and adjusted for demographics and internalizing/externalizing problem symptoms. RESULTS: Wave 1 cigarette and e-cigarette use were significantly more common among youth who used versus did not use cannabis. Among Wave 1 tobacco-naive youth, Wave 1 cannabis use was associated with significantly increased incidence of cigarette and e-cigarette use by Wave 2. CONCLUSIONS: Youth who use cannabis are more likely to report cigarette and e-cigarette use, and cannabis use is associated with increased risk of initiation of cigarette and e-cigarette use over 1 year. Continued success in tobacco control-specifically toward reducing smoking among adolescents-may require focusing on cannabis, e-cigarette, and cigarette use in public health education, outreach, and intervention efforts. IMPLICATIONS: These data extend our knowledge of cigarette and e-cigarette use among youth by showing that cannabis use is associated with increased prevalence and incidence of cigarette and e-cigarette use among youth, relative to youth who do not use cannabis. The increasing popularity of cannabis use among youth and diminished perceptions of risk, coupled with the strong link between cannabis use and tobacco use, may have unintended consequences for cigarette control efforts among youth.

Synthesis of gold nanostructures using glycine as the reducing agent.

Biological synthesis of gold nanostructures could potentially offer an environmentally friendly alternative to traditional chemical synthetic methods. During the last decades, various biomolecules, including amino acids, have been successfully used as reducing and capping agents to synthesize multi-shaped gold nanostructures. A grand challenge in this field is to increase our ability to control the size and shape of gold nanostructures formed precisely by systematic synthetic approaches based on the understanding of the mechanism for structural determination. In this study, using glycine as the model amino acid and chloroaurate (AuCl4 -) ions as the precursor solution, we report the finding that the shape of the gold nanostructures synthesized showed a strong correlation with the speciation of gold complexes determined by the pH, precursor concentration and chloride concentration of the solvent system. The gold chloro-hydroxy speciation [AuClx(OH)4-x]- (with x = 0-4) influenced the shape of the gold nanostructures formed, with gold nanoplatelets, nanotriangles, nanokites and nanoribbons observed at x = 4, 3, 2 and 1, respectively, and spherical nanoparticles observed at x = 0. Glycine was found to play a role as a reducing agent, but no significant effect on the morphology was observed, indicating the dominance of gold chloro-hydroxy speciation in the structural formation. These results collectively provide synthetic considerations to systematically synthesize non-spherical to spherical biosynthesized gold nanostructures by controlling the speciation of [AuClx(OH)4-x]-.

Cannabis use among youth in the United States, 2004-2016: Faster rate of increase among youth with depression.

BACKGROUND: Cannabis use has significant negative consequences for youth. Depression is associated with greater cannabis use among adults but less is known about cannabis use and depression among youth. This study investigated whether depression is associated with increased cannabis use among youth in the United States (US), overall and by demographics, and examined trends in cannabis use by depression status among youth from 2004 to 2016. METHODS: Data were from the 2004-2016 National Survey on Drug Use and Health (NSDUH), annual cross-sectional national samples of US persons 12 and older. The analytic sample included respondents aged 12-17 (total combined n=204,102). First, the prevalence of past-month cannabis use by past-year depression status among youth was examined, overall and by demographic subgroups, using pooled data from 2004-2016. Next, linear time trends of past-month cannabis use were assessed by depression status from 2004 to 2016 using logistic regression models with continuous year as the predictor. Models with year-by-depression status interaction terms assessed differential time trends for those with and without depression. RESULTS: From 2004-2016, cannabis use increased both among youth with and without depression. Cannabis use increased significantly more rapidly among youth with (8.45% to 11.65%), compared to without, depression (4.28% to 4.71%). Youth with depression were more than twice as likely to report cannabis use (12.86% versus 6.40%), relative to those without depression. CONCLUSIONS: Cannabis use was more than twice as common and increased more rapidly from 2004 to 2016 among youth with depression compared to youth without depression.

Trends in Cigar Use in the United States, 2002-2016: Diverging Trends by Race/Ethnicity.

INTRODUCTION: Although there are racial/ethnic differences in cigarette use, little is known about how non-cigarette tobacco use differs among racial/ethnic groups. This study investigated trends in cigar use from 2002 to 2016, by racial/ethnic group, in nationally representative US data. METHODS: Data were drawn from the 2002-2016 National Survey on Drug Use and Health public use data files (total analytic sample n = 630 547 including 54 060 past-month cigar users). Linear time trends of past-month cigar use were examined by racial/ethnic group (Non-Hispanic [NH] White, NH Black, Hispanic, NH Other/Mixed Race/Ethnicity) using logistic regression models. RESULTS: In 2016, the prevalence of past-month cigar use was significantly higher among NH Black respondents than among other racial/ethnic groups (ps < .001). Cigar use was also higher among NH White respondents than among Hispanic and NH Other/Mixed Race/Ethnicity respondents. The year by racial/ethnic group interaction was significant (p < .001). Past-month cigar use decreased significantly from 2002 to 2016 among NH White and Hispanic respondents (ps = .001), whereas no change in prevalence was observed among NH Black (p = .779) and NH Other/Mixed Race/Ethnicity respondents (p = .152). Cigar use decreased for NH White men (p < .001) and did not change for NH White women (p = .884). Conversely, cigar use increased for NH Black women (p < .001) and did not change for NH Black men (p = .546). CONCLUSIONS: Cigar use remains significantly more common among NH Black individuals in the United States and is not declining among NH Black and NH Other/Mixed Race/Ethnicity individuals over time, in contrast to declines among NH White and Hispanic individuals. IMPLICATIONS: This study identified racial/ethnic differences in trends in past-month cigar use over 15 years among annual cross-sectional samples of US individuals. The highest prevalence of cigar use in 2016 was found among NH Black individuals. In addition, cigar use prevalence did not decline from 2002 to 2016 among NH Black and NH Other/Mixed Race/Ethnicity groups over time, in contrast to NH White and Hispanic groups. Further, cigar use increased over time for NH Black women. Targeted public health and clinical efforts may be needed to decrease the prevalence of cigar use, especially for NH Black individuals.

Cigarette smoking quit ratios among adults in the USA with cannabis use and cannabis use disorders, 2002-2016.

BACKGROUND: The prevalence of cigarette smoking is nearly three times higher among persons who use cannabis and have cannabis use disorders (CUDs), relative to those who do not. The current study examined cigarette quit ratios from 2002 to 2016 among US adults with and without cannabis use and CUDs. METHODS: The current study analysed US adults aged 18 years and older from the National Survey on Drug Use and Health, an annual cross-sectional study. Quit ratios (ie, proportion of former smokers among ever-smokers) were calculated annually from 2002 to 2016. Time trends in quit ratios by cannabis use/CUDs were tested using logistic regression. RESULTS: In 2016, the quit ratios for people with any cannabis use (23%) and CUDs (15%) were less than half the quit ratios of those without cannabis use and CUDs (51% and 48%, respectively). After controlling for demographics and substance use disorders, the quit ratio did not change from 2002 to 2016 among persons with CUD, though it non-linearly increased among persons with cannabis use, without cannabis use and without CUDs. Quit ratios increased more rapidly among those who reported past-month cannabis use compared with those without past-month cannabis use. CONCLUSIONS: Cigarette smoking quit ratios remain dramatically lower among people who use cannabis and have CUDs and quit ratios did not change significantly from 2002 to 2016 among those with CUDs. Public health and clinical attention are needed to increase quit ratios and reduce harmful cigarette smoking consequences for persons with cannabis use and CUDs.

Cannabis Use Is Associated With Increased Risk of Cigarette Smoking Initiation, Persistence, and Relapse Among Adults in the United States.

INTRODUCTION: Despite increasing use of cannabis, it is unclear how cannabis use is related to cigarette transitions. This study examined cannabis use and smoking initiation, persistence, and relapse over 1 year among a nationally representative sample of US adults. METHODS: Data were from US adults (≥18 years) who completed two waves of longitudinal data from the Population Assessment of Tobacco and Health Study (Wave 1, 2013-2014; Wave 2, 2014-2015; n = 26 341). Logistic regression models were used to calculate the risk of Wave 2 incident smoking among Wave 1 never-smokers, smoking cessation among Wave 1 smokers, and smoking relapse among Wave 1 former smokers by Wave 1 cannabis use. Analyses were adjusted for age, gender, race/ethnicity, income, and education. RESULTS: Among Wave 1 never-smokers, cannabis use was associated with increased odds of initiation of nondaily (adjusted odds ratio [AOR] = 5.50, 95% confidence limits [CL] = 4.02-7.55) and daily cigarette smoking (AOR = 6.70, 95% CL = 4.75-9.46) 1 year later. Among Wave 1 daily smokers, cannabis use was associated with reduced odds of smoking cessation (AOR = 0.36, 95% CL = 0.20-0.65). Among Wave 1 former smokers, cannabis use was associated with increased odds of relapse to daily and nondaily cigarette smoking (daily AOR = 1.90, 95% CL = 1.11-3.26; nondaily AOR = 2.33, 95% CL = 1.61-3.39). CONCLUSIONS: Cannabis use was associated with increased cigarette smoking initiation, decreased smoking cessation, and increased smoking relapse among adults in the United States. Increased public education about the relationship between cannabis use and cigarette smoking transitions may be needed as cannabis use becomes more common among US adults. IMPLICATIONS: As cannabis use increases in the United States and other countries, an evaluation of the relationships of cannabis use to other health-related behaviors (eg, cigarette smoking) is needed to understand the population-level impact of legalization. Little is known about associations between cannabis use and cigarette smoking transitions (1) using recent longitudinal data, (2) among adults, and (3) examining transitions other than smoking initiation (eg, smoking relapse). Our results suggest that among US adults, cannabis use was associated with increased cigarette smoking initiation among never-smokers, decreased cigarette smoking cessation among current smokers, and increased cigarette smoking relapse among former smokers.

Isolation and Culture of Oculomotor, Trochlear, and Spinal Motor Neurons from Prenatal Islmn:GFP Transgenic Mice.

Oculomotor neurons (CN3s) and trochlear neurons (CN4s) exhibit remarkable resistance to degenerative motor neuron diseases such as amyotrophic lateral sclerosis (ALS) when compared to spinal motor neurons (SMNs). The ability to isolate and culture primary mouse CN3s, CN4s, and SMNs would provide an approach to study mechanisms underlying this selective vulnerability. To date, most protocols use heterogeneous cell cultures, which can confound the interpretation of experimental outcomes. To minimize the problems associated with mixed-cell populations, pure cultures are indispensable. Here, the first protocol describes in detail how to efficiently purify and cultivate CN3s/CN4s alongside SMNs counterparts from the same embryos using embryonic day 11.5 (E11.5) IslMN:GFP transgenic mouse embryos. The protocol provides details on the tissue dissection and dissociation, FACS-based cell isolation, and in vitro cultivation of cells from CN3/CN4 and SMN nuclei. This protocol adds a novel in vitro CN3/CN4 culture system to existing protocols and simultaneously provides a pure species- and age-matched SMN culture for comparison. Analyses focusing on the morphological, cellular, molecular, and electrophysiological characteristics of motor neurons are feasible in this culture system. This protocol will enable research into the mechanisms that define motor neuron development, selective vulnerability, and disease.

Highly enhanced voltage holding property for low-frequency-driven fringe-field switching liquid crystal mode by charge-trapping effect of carbon-nanotube-doped surface.

We herein propose a multiwalled carbon nanotube (MWCNT) doping method into liquid crystal (LC) alignment polyimides (PIs) with low resistivity for resolving both issues of voltage holding and image sticking in low-frequency-driven fringe-field switching (FFS) LC modes using negative dielectric LCs (n-LCs). By utilizing strong ion trapping ability of MWCNTs, the FFS n-LC cell aligned by low resistivity PIs with 0.05 wt% MWCNT doping exhibited an excellent voltage holding ratio of 99% under an extremely low operation frequency of 0.5 Hz and approximately 23.6 times better surface discharging property than that aligned by high resistivity PIs.

Non-catalytic Roles of Tet2 Are Essential to Regulate Hematopoietic Stem and Progenitor Cell Homeostasis.

The Ten-eleven translocation (TET) enzymes regulate gene expression by promoting DNA demethylation and partnering with chromatin modifiers. TET2, a member of this family, is frequently mutated in hematological disorders. The contributions of TET2 in hematopoiesis have been attributed to its DNA demethylase activity, and the significance of its nonenzymatic functions has remained undefined. To dissect the catalytic and non-catalytic requirements of Tet2, we engineered catalytically inactive Tet2 mutant mice and conducted comparative analyses of Tet2 mutant and Tet2 knockout animals. Tet2 knockout mice exhibited expansion of hematopoietic stem and progenitor cells (HSPCs) and developed myeloid and lymphoid disorders, while Tet2 mutant mice predominantly developed myeloid malignancies reminiscent of human myelodysplastic syndromes. HSPCs from Tet2 knockout mice exhibited distinct gene expression profiles, including downregulation of Gata2. Overexpression of Gata2 in Tet2 knockout bone marrow cells ameliorated disease phenotypes. Our results reveal the non-catalytic roles of TET2 in HSPC homeostasis.

Rinf Regulates Pluripotency Network Genes and Tet Enzymes in Embryonic Stem Cells.

The Retinoid inducible nuclear factor (Rinf), also known as CXXC5, is a nuclear protein, but its functions in the context of the chromatin are poorly defined. We find that in mouse embryonic stem cells (mESCs), Rinf binds to the chromatin and is enriched at promoters and enhancers of Tet1, Tet2, and pluripotency genes. The Rinf-bound regions show significant overlapping occupancy of pluripotency factors Nanog, Oct4, and Sox2, as well as Tet1 and Tet2. We found that Rinf forms a complex with Nanog, Oct4, Tet1, and Tet2 and facilitates their proper recruitment to regulatory regions of pluripotency and Tet genes in ESCs to positively regulate their transcription. Rinf deficiency in ESCs reduces expression of Rinf target genes, including several pluripotency factors and Tet enzymes, and causes aberrant differentiation. Together, our findings establish Rinf as a regulator of the pluripotency network genes and Tet enzymes in ESCs.

Stem cell-derived cranial and spinal motor neurons reveal proteostatic differences between ALS resistant and sensitive motor neurons.

In amyotrophic lateral sclerosis (ALS) spinal motor neurons (SpMN) progressively degenerate while a subset of cranial motor neurons (CrMN) are spared until late stages of the disease. Using a rapid and efficient protocol to differentiate mouse embryonic stem cells (ESC) to SpMNs and CrMNs, we now report that ESC-derived CrMNs accumulate less human (h)SOD1 and insoluble p62 than SpMNs over time. ESC-derived CrMNs have higher proteasome activity to degrade misfolded proteins and are intrinsically more resistant to chemically-induced proteostatic stress than SpMNs. Chemical and genetic activation of the proteasome rescues SpMN sensitivity to proteostatic stress. In agreement, the hSOD1 G93A mouse model reveals that ALS-resistant CrMNs accumulate less insoluble hSOD1 and p62-containing inclusions than SpMNs. Primary-derived ALS-resistant CrMNs are also more resistant than SpMNs to proteostatic stress. Thus, an ESC-based platform has identified a superior capacity to maintain a healthy proteome as a possible mechanism to resist ALS-induced neurodegeneration.

Racial/ethnic differences in daily, nondaily, and menthol cigarette use and smoking quit ratios in the United States: 2002 to 2016.

In the United States (US), racial/ethnic groups differ in cigarette smoking behaviors. We examined changes in cigarette prevalence and quit ratios over 15 years by racial/ethnic group (Non-Hispanic (NH) White, NH Black, Hispanic, NH Other). Data were drawn from the 2002-2016 National Survey on Drug Use and Health (NSDUH) public use data files and analyzed in 2018. Linear time trends of the prevalence of daily, nondaily, and menthol cigarette use and quit ratios (i.e., proportion of former smokers among lifetime smokers) were assessed using logistic regression models. 19.35% of NH White persons were daily smokers in 2016; this prevalence was significantly higher than all other groups (NH Black 10.99%, Hispanic 6.81%, NH Other 9.10%). Menthol use was significantly more common among NH Black individuals than all other groups in every year from 2002 to 2016 (2016: NH Black 23.38%, NH White 14.52%, Hispanic 10.49%, NH Other 8.97%). From 2002 to 2016, daily and nondaily smoking decreased significantly among all groups. The rate of decline of nondaily smoking was more rapid among Hispanic than NH White individuals while the rate of menthol smoking decline was more rapid among NH White than among Hispanic individuals. The quit ratio did not change significantly from 2002 to 2016 among NH Black individuals (31% to 35%) in contrast to a significant increase among NH White (2002, 45%; 2016, 50%) and Hispanic (2002, 33%; 2016, 41%) individuals. Further progress in tobacco control for vulnerable groups may need to include innovative strategies to address these concerning trends.

Serious psychological distress and daily cannabis use, 2008 to 2016: Potential implications for mental health?

BACKGROUND: Daily cannabis use is increasing in the United States (US). Yet, it is not known whether daily cannabis use is disproportionately common, or whether it has increased differentially over time, by mental health status. This study estimated the prevalence of daily cannabis use among adults in the US with and without past-month serious psychological distress (SPD; measured by the Kessler Psychological Distress Scale (K6)) in 2016 and estimated trends in daily cannabis use by past-30-day SPD status from 2008 to 2016. METHODS: Data were drawn from adults age 18 and older in the 2008-2016 National Survey on Drug Use and Health (combined total analytic sample n = 356,413). Linear time trends of daily cannabis use, stratified by SPD status, were assessed using logistic regression models with continuous year as the predictor. RESULTS: In 2016, past-month daily cannabis use was significantly more common among those with past-month SPD (8.07%), compared to those without past-month SPD (2.66%). Daily cannabis use increased significantly from 2008 to 2016 among those both with and without SPD although use among those with SPD was persistently higher than use among those without SPD over the time period studied. CONCLUSIONS: Daily cannabis use is significantly more common among persons with serious psychological distress and is increasing in this group, as well as among those without. Given this increase and the high prevalence of cannabis use among those with SPD, it may be important to consider potential consequences of this increased use for those with mental health vulnerabilities.

Low-Loading of Pt Nanoparticles on 3D Carbon Foam Support for Highly Active and Stable Hydrogen Production.

Minimizing Pt loading is essential for designing cost-effective water electrolyzers and fuel cell systems. Recently, three-dimensional macroporous open-pore electroactive supports have been widely regarded as promising architectures to lower loading amounts of Pt because of its large surface area, easy electrolyte access to Pt sites, and superior gas diffusion properties to accelerate diffusion of H2 bubbles from the Pt surface. However, studies to date have mainly focused on Pt loading on Ni-based 3D open pore supports which are prone to corrosion in highly acidic and alkaline conditions. Here, we investigate electrodeposition of Pt nanoparticles in low-loading amounts on commercially available, inexpensive, 3D carbon foam (CF) support and benchmark their activity and stability for electrolytic hydrogen production. We first elucidate the effect of deposition potential on the Pt nanoparticle size, density and subsequently its coverage on 3D CF. Analysis of the Pt deposit using scanning electron microscopy images reveal that for a given deposition charge density, the particle density increases (with cubic power) and particle size decreases (linearly) with deposition overpotential. A deposition potential of -0.4 V vs. standard calomel electrode (SCE) provided the highest Pt nanoparticle coverage on 3D CF surface. Different loading amounts of Pt (0.0075-0.1 mgPt/cm2) was then deposited on CF at -0.4 V vs. SCE and subsequently studied for its hydrogen evolution reaction (HER) activity in acidic 1M H2SO4 electrolyte. The Pt/CF catalyst with loading amounts as low as 0.06 mgPt/cm2 (10-fold lower than state-of-the-art commercial electrodes) demonstrated a mass activity of 2.6 ampere per milligram Pt at 200 mV overpotential, nearly 6-fold greater than the commercial Pt/C catalyst tested under similar conditions. The 3D architectured electrode also demonstrated excellent stability, showing <7% loss in activity after 60 h of constant current water electrolysis at 100 mA/cm2.

Fast-switching optically isotropic liquid crystal nano-droplets with improved depolarization and Kerr effect by doping high k nanoparticles.

We proposed and analyzed an optically isotropic nano-droplet liquid crystal (LC) doped with high k nanoparticles (NPs), exhibiting enhanced Kerr effects, which could be operated with reduced driving voltages. For enhancing the contrast ratio together with the light efficiencies, the LC droplet sizes were adjusted to be shorter than the wavelength of visible light to reduce depolarization effects by optical scattering of the LC droplets. Based on the optical analysis of the depolarization effects, the influence of the relationship between the LC droplet size and the NP doping ratio on the Kerr effect change was investigated.

Earth-Abundant Tin Sulfide-Based Photocathodes for Solar Hydrogen Production.

Tin-based chalcogenide semiconductors, though attractive materials for photovoltaics, have to date exhibited poor performance and stability for photoelectrochemical applications. Here, a novel strategy is reported to improve performance and stability of tin monosulfide (SnS) nanoplatelet thin films for H2 production in acidic media without any use of sacrificial reagent. P-type SnS nanoplatelet films are coated with the n-CdS buffer layer and the TiO2 passivation layer to form type II heterojunction photocathodes. These photocathodes with subsequent deposition of Pt nanoparticles generate a photovoltage of 300 mV and a photocurrent density of 2.4 mA cm-2 at 0 V versus reversible hydrogen electrode (RHE) for water splitting under simulated visible-light illumination (λ > 500 nm, Pin = 80 mW cm-2). The incident photon-to-current efficiency at 0 V versus RHE for H2 production reach a maximum of 12.7% at 575 nm with internal quantum efficiency of 13.8%. The faradaic efficiency for hydrogen evolution remains close to unity after 6000 s of illumination, confirming the robustness of the heterojunction for solar H2 production.

Dual-reporter SERS-based biomolecular assay with reduced false-positive signals.

We present a sensitive and quantitative protein detection assay that can efficiently distinguish between specific and nonspecific target binding. Our technique combines dual affinity reagents with surface-enhanced Raman spectroscopy (SERS) and chemometric analysis. We link one Raman reporter-tagged affinity reagent to gold nanoparticles and another to a gold film, such that protein-binding events create a "hot spot" with strong SERS spectra from both Raman reporter molecules. Any signal generated in this context is indicative of recognition by both affinity labels, whereas signals generated by nonspecific binding lack one or the other label, enabling us to efficiently distinguish true from false positives. We show that the number of hot spots per unit area of our substrate offers a quantitative measure of analyte concentration and demonstrate that this dual-label, SERS-linked aptasensor assay can sensitively and selectively detect human α-thrombin in 1% human serum with a limit of detection of 86 pM.

An Optically Isotropic Antiferroelectric Liquid Crystal (OI-AFLC) Display Mode Operating over a Wide Temperature Range using Ternary Bent-Core Liquid Crystal Mixtures.

We report on the synthesis and characterization of bent-core liquid crystal (LC) compounds and the preparation of mixtures that provide an optically isotropic antiferroelectric (OI-AFLC) liquid crystal display mode over a very wide temperature interval and well below room temperature. From the collection of compounds synthesized during this study, we recognized that several ternary mixtures displayed a modulated SmCaPA phase down to below -40 °C and up to about 100 °C on both heating and cooling, as well as optical tilt angles in the transformed state of approximately 45° (optically isotropic state). The materials were fully characterized and their liquid crystal as well as electro-optical properties analyzed by polarized optical microscopy, differential scanning calorimetry, synchrotron X-ray diffraction, dielectric spectroscopy, and electro-optical tests.