Geometric Symmetry Breaking and Nonlinearity Can Increase Thermoelectric Power.

Direct thermal-to-electric energy converters typically operate in the linear regime, where the ratio of actual maximum power relative to the ideal maximum power, the so-called fill factor (FF), is 0.25. Here, we show, based on fundamental symmetry considerations, that the leading order nonlinear terms that can increase the FF require devices with broken spatial symmetry. Studying nonlinear, thermoelectric transport across an asymmetric energy barrier defined in a single semiconductor nanowire, we find in both experiment and theory that we can increase the FF as well as maximum power. Geometric symmetry breaking combined with the design of nonlinear behavior thus represents a strategy for increasing the performance of thermoelectric or hot-carrier devices.

Quantifying PG : VG ratio and nicotine content in commercially available e-liquids using handheld Raman spectroscopy.

Electronic cigarettes are a popular nicotine consumption product that have risen in popularity as an alternative to cigarettes. However, their recent meteoric rise in market size and various controversies have resulted in the analyses of e-liquid ingredients to be focused on powerful laboratory-based slow methods such as chromatography and mass spectrometry. Here we present a complementary technology based on Raman spectroscopy combined with chemometrics as a fast, inexpensive, and highly portable screening tool to detect and quantify the propylene glycol : glycerol (PG : VG) ratio and nicotine content of e-cigarette liquids. Through this, the PG : VG ratio of 20 out of 23 commercial samples was quantified to within 3% of their stated value, while nicotine was successfully quantified to within 1 mg g-1 for 16 out of 23 samples without the need for accurate knowledge of flavonoid composition. High linearity was also achieved when flavours were kept constant. Finally, the limitations of Raman spectroscopy are discussed, and potential solutions are suggested.

Antimicrobial Evaluation of New Pyrazoles, Indazoles and Pyrazolines Prepared in Continuous Flow Mode.

Multi-drug resistant bacterial strains (MDR) have become an increasing challenge to our health system, resulting in multiple classical antibiotics being clinically inactive today. As the de-novo development of effective antibiotics is a very costly and time-consuming process, alternative strategies such as the screening of natural and synthetic compound libraries is a simple approach towards finding new lead compounds. We thus report on the antimicrobial evaluation of a small collection of fourteen drug-like compounds featuring indazoles, pyrazoles and pyrazolines as key heterocyclic moieties whose synthesis was achieved in continuous flow mode. It was found that several compounds possessed significant antibacterial potency against clinical and MDR strains of the Staphylococcus and Enterococcus genera, with the lead compound (9) reaching MIC values of 4 µg/mL on those species. In addition, time killing experiments performed on compound 9 on Staphylococcus aureus MDR strains highlight its activity as bacteriostatic. Additional evaluations regarding the physiochemical and pharmacokinetic properties of the most active compounds are reported and showcased, promising drug-likeness, which warrants further explorations of the newly identified antimicrobial lead compound.

Revisiting the Assessment of Strength, Power, and Change of Direction in Collegiate American Football Athletes.

ABSTRACT: Burke, AA, Guthrie, BM, Magee, M, Miller, AD, and Jones, MT. Revisiting the assessment of strength, power, and change of direction in collegiate american football athletes. J Strength Cond Res 37(8): 1623-1627, 2023-The primary purpose was to assess the effect of strength on vertical jump (VJ) and change of direction (COD) with a secondary purpose to examine if these relationships were moderated by the sport position group through path analysis using structural equation modeling. Subjects were collegiate American football athletes grouped by skill (SK; n = 98) and nonskill (NS; n = 83) sport position groups. Maximal strength was assessed by 1 repetition maximum back squat and hang clean (HC). Vertical jump was used to evaluate power. Change of direction was assessed through the 20-yard shuttle (i.e., 5-10-5) test. Multigroup path analysis examined causal pathways among variables and moderating effects of sport position. The final model revealed that VJ fully mediated the relationship between HC and COD (HC-VJ: ß = 0.408, p < 0.001; VJ-COD: ß = -0.376, p < 0.001; and HC-COD: ß = -0.137, p = 0.17) in SK. The NS showed only direct effects of HC on COD ( ß = -0.335, p < 0.001). These findings suggest that strength does not solely explain COD ability but also can serve to enhance underpinning qualities, such as relative force production in the VJ. Relationships between strength, power, and COD are different depending on the positional group. The results provide further insight into performance outcomes in field tests. It is recommended that sport position differences be considered when assessing and analyzing physical qualities in a team setting within the sport of American football.

Heat Driven Transport in Serial Double Quantum Dot Devices.

Studies of thermally induced transport in nanostructures provide access to an exciting regime where fluctuations are relevant, enabling the investigation of fundamental thermodynamic concepts and the realization of thermal energy harvesters. We study a serial double quantum dot formed in an InAs/InP nanowire coupled to two electron reservoirs. By means of a specially designed local metallic joule-heater, the temperature of the phonon bath in the vicinity of the double quantum dot can be enhanced. This results in phonon-assisted transport, enabling the conversion of local heat into electrical power in a nanosized heat engine. Simultaneously, the electron temperatures of the reservoirs are affected, resulting in conventional thermoelectric transport. By detailed modeling and experimentally tuning the interdot coupling, we disentangle both effects. Furthermore, we show that phonon-assisted transport is sensitive to excited states. Our findings demonstrate the versatility of our design to study fluctuations and fundamental nanothermodynamics.

Hot-Carrier Extraction in Nanowire-Nanoantenna Photovoltaic Devices.

Nanowires bring new possibilities to the field of hot-carrier photovoltaics by providing flexibility in combining materials for band engineering and using nanophotonic effects to control light absorption. Previously, an open-circuit voltage beyond the Shockley-Queisser limit was demonstrated in hot-carrier devices based on InAs-InP-InAs nanowire heterostructures. However, in these first experiments, the location of light absorption, and therefore the precise mechanism of hot-carrier extraction, was uncontrolled. In this Letter, we combine plasmonic nanoantennas with InAs-InP-InAs nanowire devices to enhance light absorption within a subwavelength region near an InP energy barrier that serves as an energy filter. From photon-energy- and irradiance-dependent photocurrent and photovoltage measurements, we find that photocurrent generation is dominated by internal photoemission of nonthermalized hot electrons when the photoexcited electron energy is above the barrier and by photothermionic emission when the energy is below the barrier. We estimate that an internal quantum efficiency up to 0.5-1.2% is achieved. Insights from this study provide guidelines to improve internal quantum efficiencies based on nanowire heterostructures.

Hot-carrier separation in heterostructure nanowires observed by electron-beam induced current.

The separation of hot carriers in semiconductors is of interest for applications such as thermovoltaic photodetection and third-generation photovoltaics. Semiconductor nanowires offer several potential advantages for effective hot-carrier separation such as: a high degree of control and flexibility in heterostructure-based band engineering, increased hot-carrier temperatures compared to bulk, and a geometry well suited for local control of light absorption. Indeed, InAs nanowires with a short InP energy barrier have been observed to produce electric power under global illumination, with an open-circuit voltage exceeding the Shockley-Queisser limit. To understand this behaviour in more detail, it is necessary to establish control over the precise location of electron-hole pair-generation in the nanowire. In this work we perform electron-beam induced current measurements with high spatial resolution, and demonstrate the role of the InP barrier in extracting energetic electrons.We interprete the results in terms of hot-carrier separation, and extract estimates of the hot carriers' mean free path.

Evaluation of Direct from Sample Metabolomics of Human Feces Using Rapid Evaporative Ionization Mass Spectrometry.

Mass spectrometry is a powerful tool in the investigation of the human fecal metabolome. However, current approaches require time-consuming sample preparation, chromatographic separations, and consequently long analytical run times. Rapid evaporative ionization mass spectrometry (REIMS) is a method of ambient ionization mass spectrometry and has been utilized in the metabolic profiling of a diverse range of biological materials, including human tissue, cell culture lines, and microorganisms. Here, we describe the use of an automated, high-throughput REIMS robotic platform for direct analysis of human feces. Through the analysis of fecal samples from five healthy male participants, REIMS analytical parameters were optimized and used to assess the chemical information obtainable using REIMS. Within the fecal samples analyzed, bile acids, including primary, secondary, and conjugate species, were identified, and phospholipids of possible bacterial origin were detected. In addition, the effect of storage conditions and consecutive freeze/thaw cycles was determined. Within the REIMS mass spectra, the lower molecular weight metabolites, such as fatty acids, were shown to be significantly affected by storage conditions for prolonged periods at temperatures above -80 °C and consecutive freeze/thaw cycles. However, the complex lipid region was shown to be unaffected by these conditions. A further cohort of 50 fecal samples, collected from patients undergoing bariatric surgery, were analyzed using the optimized REIMS parameters and the complex lipid region mass spectra used for multivariate modeling. This analysis showed a predicted separation between pre- and post-surgery specimens, suggesting that REIMS analysis can detect biological differences, such as microbiome-level differences, which have traditionally been reliant upon methods utilizing extensive sample preparations and chromatographic separations and/or DNA sequencing.

Thermoelectric Power Factor Limit of a 1D Nanowire.

In the past decade, there has been significant interest in the potentially advantageous thermoelectric properties of one-dimensional (1D) nanowires, but it has been challenging to find high thermoelectric power factors based on 1D effects in practice. Here we point out that there is an upper limit to the thermoelectric power factor of nonballistic 1D nanowires, as a consequence of the recently established quantum bound of thermoelectric power output. We experimentally test this limit in quasiballistic InAs nanowires by extracting the maximum power factor of the first 1D subband through I-V characterization, finding that the measured maximum power factors conform to the theoretical limit. The established limit allows the prediction of the achievable power factor of a specific nanowire material system with 1D electronic transport based on the nanowire dimension and mean free path. The power factor of state-of-the-art semiconductor nanowires with small cross section and high crystal quality can be expected to be highly competitive (on the order of mW/m K^{2}) at low temperatures. However, they have no clear advantage over bulk materials at, or above, room temperature.

Thermoelectric Characterization of the Kondo Resonance in Nanowire Quantum Dots.

We experimentally verify hitherto untested theoretical predictions about the thermoelectric properties of Kondo correlated quantum dots (QDs). The specific conditions required for this study are obtained by using QDs epitaxially grown in nanowires, combined with a recently developed method for controlling and measuring temperature differences at the nanoscale. This makes it possible to obtain data of very high quality both below and above the Kondo temperature, and allows a quantitative comparison with theoretical predictions. Specifically, we verify that Kondo correlations can induce a polarity change of the thermoelectric current, which can be reversed either by increasing the temperature or by applying a magnetic field.

Bipolar Photothermoelectric Effect Across Energy Filters in Single Nanowires.

The photothermoelectric (PTE) effect uses nonuniform absorption of light to produce a voltage via the Seebeck effect and is of interest for optical sensing and solar-to-electric energy conversion. However, the utility of PTE devices reported to date has been limited by the need to use a tightly focused laser spot to achieve the required, nonuniform illumination and by their dependence upon the Seebeck coefficients of the constituent materials, which exhibit limited tunability and, generally, low values. Here, we use InAs/InP heterostructure nanowires to overcome these limitations: first, we use naturally occurring absorption "hot spots" at wave mode maxima within the nanowire to achieve sharp boundaries between heated and unheated subwavelength regions of high and low absorption, allowing us to use global illumination; second, we employ carrier energy-filtering heterostructures to achieve a high Seebeck coefficient that is tunable by heterostructure design. Using these methods, we demonstrate PTE voltages of hundreds of millivolts at room temperature from a globally illuminated nanowire device. Furthermore, we find PTE currents and voltages that change polarity as a function of the wavelength of illumination due to spatial shifting of subwavelength absorption hot spots. These results indicate the feasibility of designing new types of PTE-based photodetectors, photothermoelectrics, and hot-carrier solar cells using nanowires.

Single-nanowire, low-bandgap hot carrier solar cells with tunable open-circuit voltage.

Compared to traditional pn-junction photovoltaics, hot carrier solar cells offer potentially higher efficiency by extracting work from the kinetic energy of photogenerated 'hot carriers' before they cool to the lattice temperature. Hot carrier solar cells have been demonstrated in high-bandgap ferroelectric insulators and GaAs/AlGaAs heterostructures, but so far not in low-bandgap materials, where the potential efficiency gain is highest. Recently, a high open-circuit voltage was demonstrated in an illuminated wurtzite InAs nanowire with a low bandgap of 0.39 eV, and was interpreted in terms of a photothermoelectric effect. Here, we point out that this device is a hot carrier solar cell and discuss its performance in those terms. In the demonstrated devices, InP heterostructures are used as energy filters in order to thermoelectrically harvest the energy of hot electrons photogenerated in InAs absorber segments. The obtained photovoltage depends on the heterostructure design of the energy filter and is therefore tunable. By using a high-resistance, thermionic barrier, an open-circuit voltage is obtained that is in excess of the Shockley-Queisser limit. These results provide generalizable insight into how to realize high voltage hot carrier solar cells in low-bandgap materials, and therefore are a step towards the demonstration of higher efficiency hot carrier solar cells.

Prevalence and patterns of use of mantra, mindfulness and spiritual meditation among adults in the United States.

BACKGROUND: Despite a growing body of scientific literature exploring the nature of meditation there is limited information on the characteristics of individuals who use it. This is particularly true of comparative studies examining prevalence and predictors of use of various forms of meditation. METHODS: A secondary analysis was conducted using data from the 2012 National Health Interview Survey (n = 34,525). Three popular forms of meditation were compared-mantra, mindfulness, and spiritual-to determine lifetime and 12-month use related to key sociodemographic, health behavior, health status, and healthcare access variables. RESULTS: The 12-month prevalence for meditation practice was 3.1% for spiritual meditation, 1.9% for mindfulness meditation, and 1.6% for mantra meditation. This represents approximately 7.0, 4.3, and 3.6 million adults respectively. A comparison across the three meditation practices found many similarities in user characteristics, suggesting interest in meditation may be more related to the type of person meditating than to the type of practice selected. Across meditation styles use was more prevalent among respondents who were female, non-Hispanic White, college educated, physically active; who used other complementary health practices; and who reported depression. Higher utilization of conventional healthcare services was one of the strongest predictors of use of all three styles. In addition to similarities, important distinctions were observed. For example, spiritual meditation practice was more prevalent among former drinkers. This may reflect use of spiritual meditation practices in support of alcohol treatment and sobriety. Reasons for use of meditation were examined using the sample of respondents who practiced mindfulness meditation. Wellness and prevention (74%) was a more common reason than use to treat a specific health condition (30%). Common reasons for use included stress management (92%) and emotional well-being (91%), and to support other health behaviors. Meditation was viewed positively because it was self-care oriented (81%) and focused on the whole person (79%). CONCLUSION: Meditation appears to provide an accessible, self-care resource that has potential value for mental health, behavioral self-regulation, and integrative medical care. Considering consumer preference for distinct types of meditation practices, understanding the underlying mechanisms, benefits, and applications of practice variations is important.

Automated High-Throughput Identification and Characterization of Clinically Important Bacteria and Fungi using Rapid Evaporative Ionization Mass Spectrometry.

Rapid evaporative ionization mass spectrometry (REIMS) has been shown to quickly and accurately speciate microorganisms based upon their species-specific lipid profile. Previous work by members of this group showed that the use of a hand-held bipolar probe allowed REIMS to analyze microbial cultures directly from culture plates without any prior preparation. However, this method of analysis would likely be unsuitable for a high-throughput clinical microbiology laboratory. Here, we report the creation of a customized platform that enables automated, high-throughput REIMS analysis that requires minimal user input and operation and is suitable for use in clinical microbiology laboratories. The ability of this high-throughput platform to speciate clinically important microorganisms was tested through the analysis of 375 different clinical isolates collected from distinct patient samples from 25 microbial species. After optimization of our data analysis approach, we achieved substantially similar results between the two REIMS approaches. For hand-held bipolar probe REIMS, a speciation accuracy of 96.3% was achieved, whereas for high-throughput REIMS, an accuracy of 93.9% was achieved. Thus, high-throughput REIMS offers an alternative mass spectrometry based method for the rapid and accurate identification of clinically important microorganisms in clinical laboratories without any preanalysis preparative steps.

Educational Interventions to Promote Healthy Nutrition and Physical Activity Among Older Chinese Americans: A Cluster-Randomized Trial.

OBJECTIVES: To evaluate the efficacy of an in-language intervention of 2 lectures plus printed materials versus printed materials alone on knowledge and adherence to nutrition and physical activity guidelines among older Chinese Americans in San Francisco, California. METHODS: From August 2010 to September 2013, we randomized 756 Chinese Americans aged 50 to 75 years to either lectures plus print (n = 361) or print (n = 357). Clusters were the participants recruited by each lay health worker. Intervention outcomes were changes in knowledge of recommended vegetable intake, fruit intake, and physical activity level and adherence to those recommendations from pre- to 6 months postintervention. RESULTS: The retention rate was 99%. At baseline, knowledge and adherence to recommendations were low. Print yielded increases in knowledge of recommended vegetable intake and physical activity level and adherence to fruit intake and physical activity recommendations. Lectures plus print had significant increases in all 6 outcomes. In multivariable models, lectures plus print was superior to print for knowledge of vegetable (adjusted odds ratio [AOR] = 12.61; 95% confidence interval [CI] = 6.50, 24.45) and fruit (AOR = 16.16; 95% CI = 5.61, 46.51) intake recommendations and adherence to vegetable intake recommendations (AOR = 5.53; 95% CI = 1.96, 15.58). CONCLUSIONS: In-language print materials, alone and combined with lectures, increased nutrition and physical activity knowledge and behaviors among older Chinese Americans.

Healthcare Communication Barriers and Self-Rated Health in Older Chinese American Immigrants.

Older Chinese immigrants are a growing population in the United States who experience multiple healthcare communication barriers such as limited English proficiency and low health literacy. Each of these obstacles has been associated with poor health outcomes but less is known about their effects in combination. This study examined the association between healthcare communication barriers and self-rated health among older Chinese immigrants. Cross-sectional survey data were obtained from 705 Chinese American immigrants ages 50-75 living in San Francisco, California. Communication barriers examined included spoken English proficiency, medical interpreter needs, and health literacy in written health information. The study sample (81 % females, mean age = 62) included 67 % who spoke English poorly or not at all, 34 % who reported needing a medical interpreter, and 37 % who reported "often" or "always" needing assistance to read health information. Two-thirds reported poor self-rated health; many reported having access to racial-concordant (74 %) and language-concordant (86 %) healthcare services. Both poor spoken English proficiency and low health literacy were associated with poor self-rated health, independent of other significant correlates (unemployment, chronic health conditions, and having a primary doctor who was ethnic Chinese). Results revealed that spoken English proficiency and print health literacy are independent communication barriers that are directly associated with health status among elderly Chinese American immigrants. Access to racial- or language-concordant health care services did not appear to resolve these barriers. These findings underscore the importance of addressing both spoken and written healthcare communication needs among older Chinese American immigrants.

Electron-beam patterning of polymer electrolyte films to make multiple nanoscale gates for nanowire transistors.

We report an electron-beam based method for the nanoscale patterning of the poly(ethylene oxide)/LiClO4 polymer electrolyte. We use the patterned polymer electrolyte as a high capacitance gate dielectric in single nanowire transistors and obtain subthreshold swings comparable to conventional metal/oxide wrap-gated nanowire transistors. Patterning eliminates gate/contact overlap, which reduces parasitic effects and enables multiple, independently controllable gates. The method's simplicity broadens the scope for using polymer electrolyte gating in studies of nanowires and other nanoscale devices.

Engaging traditional medicine providers in colorectal cancer screening education in a chinese american community: a pilot study.

INTRODUCTION: Although colorectal cancer (CRC) screening is effective in preventing colon cancer, it remains underused by Asian Americans. Because Chinese Americans often use traditional Chinese medicine (TCM), we conducted a pilot study to explore the feasibility and acceptability of having TCM providers deliver education about CRC screening. METHODS: Four TCM providers (2 herbalists and 2 acupuncturists) were trained to deliver small-group educational sessions to promote CRC screening. Each provider recruited 15 participants aged 50 to 75. Participants completed a baseline survey on CRC-related knowledge, attitudes, and behaviors and then attended one 2-hour educational session delivered by the providers in Cantonese or Mandarin. Three months later, participants completed a postintervention survey. RESULTS: Sixty participants were recruited from the San Francisco Chinatown neighborhood. The average age was 62.4 years. Most participants had limited English proficiency (96.7%), annual household income less than $20,000 per year (60%), and low educational attainment (65.1% < high school education). At postintervention (n = 57), significant increases were found in having heard of CRC (from 52.6% to 79.0%, P < .001) and colon polyps (from 64.9% to 84.2%, P < .001). Knowledge regarding screening frequency recommendations also increased significantly. The rate of ever having received any CRC screening test increased from 71.9% to 82.5% (P <.001). The rate of up-to-date screening increased from 70.2% to 79.0% (P = .04). CONCLUSION: The findings suggest that TCM providers can be trained to deliver culturally and linguistically appropriate outreach on CRC screening within their community. Participants reached by TCM providers increased CRC knowledge and self-reported CRC screening.

A yoga intervention for type 2 diabetes risk reduction: a pilot randomized controlled trial.

BACKGROUND: Type 2 diabetes is a major health problem in many countries including India. Yoga may be an effective type 2 diabetes prevention strategy in India, particularly given its cultural familiarity. METHODS: This was a parallel, randomized controlled pilot study to collect feasibility and preliminary efficacy data on yoga for diabetes risk factors among people at high risk of diabetes. Primary outcomes included: changes in BMI, waist circumference, fasting blood glucose, postprandial blood glucose, insulin, insulin resistance, blood pressure, and cholesterol. We also looked at measures of psychological well-being including changes in depression, anxiety, positive and negative affect and perceived stress. Forty-one participants with elevated fasting blood glucose in Bangalore, India were randomized to either yoga (n = 21) or a walking control (n = 20). Participants were asked to either attend yoga classes or complete monitored walking 3-6 days per week for eight weeks. Randomization and allocation was performed using computer-generated random numbers and group assignments delivered in sealed, opaque envelopes generated by off-site study staff. Data were analyzed based on intention to treat. RESULTS: This study was feasible in terms of recruitment, retention and adherence. In addition, yoga participants had significantly greater reductions in weight, waist circumference and BMI versus control (weight -0.8 ± 2.1 vs. 1.4 ± 3.6, p = 0.02; waist circumference -4.2 ± 4.8 vs. 0.7 ± 4.2, p < 0.01; BMI -0.2 ± 0.8 vs. 0.6 ± 1.6, p = 0.05). There were no between group differences in fasting blood glucose, postprandial blood glucose, insulin resistance or any other factors related to diabetes risk or psychological well-being. There were significant reductions in systolic and diastolic blood pressure, total cholesterol, anxiety, depression, negative affect and perceived stress in both the yoga intervention and walking control over the course of the study. CONCLUSION: Among Indians with elevated fasting blood glucose, we found that participation in an 8-week yoga intervention was feasible and resulted in greater weight loss and reduction in waist circumference when compared to a walking control. Yoga offers a promising lifestyle intervention for decreasing weight-related type 2 diabetes risk factors and potentially increasing psychological well-being. TRIAL REGISTRATION: ClinicalTrials.gov Identified NCT00090506.

Re-examining religiosity as a protective factor: comparing alcohol use by self-identified religious, spiritual, and secular college students.

Religiosity has been found to be associated with lower alcohol use by college students. The majority of studies on this topic, however, fail to differentiate religiosity and spirituality. This is potentially problematic due to the changing face of religion in America today. A study was conducted to explore similarities and differences between self-identified religious and spiritual college students. A modified version of the Core Alcohol and Drug Survey was administered online with a sample of 2,312 students. As hypothesized, self-identified religious and spiritual students differed significantly on key variables related to religious practices, alcohol consumption, and postmodern social values.