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Pyrazolines and their pyrazole congeners are important heterocyclic building blocks with numerous applications in the fine chemical industries. However, traditional routes towards these entities are based on multistep syntheses generating substantial amounts of chemical waste. Here we report an alternative approach using UV-light to convert tetrazoles into pyrazolines via a reagent-free photo-click strategy. This route generates nitrile imine dipoles in situ that are trapped with different dipolarophiles rendering a selection of these heterocyclic targets in high chemical yields. A continuous flow method is ultimately realized that generates multigram quantities of product in a safe and readily scalable manner thus demonstrating the value of this photochemical approach for future exploitations in industry.

This study investigates the user experience in cloud-based environments. As a result of the Coronavirus Disease 2019 (COVID-19)restrictions, we were not able to execute the experiments as initially planned and hence this study is being presented as a pilot experiment that can be used as a prototype in future research. The aim of these experiments is to find a metric that can be used in estimating the performance of remote desktop systems. This study mainly focuses on latency, within and across networks, as the primary factor in the remote-desktop user experience. © 2002 Society of Motion Picture and Television Engineers, Inc.

Load carriage (LC) is a contributing factor to musculoskeletal injury in many occupations. Given that falls are a common mechanism of injury for those frequently engaging in LC, understanding the effects of LC on postural stability (PS) is necessary. A systematic review and meta-analysis was conducted to examine effects of LC on PS. Sixteen and 9 studies were included in the qualitative and quantitative synthesis, respectively. In most studies, it was found that LC leads to a decrease in PS with significant effects on center of pressure (COP) sway area (standardized mean difference = 0.45; p 0.005) and COP anterior-posterior excursion (standardized mean difference = 0.52; p 0.05). Furthermore, load magnitude and load placement are factors which can significantly affect COP measures of PS. It is recommended to minimize load magnitude and equally distribute load when possible to minimize LC effects on PS. Future research should examine additional factors contributing to differences in individual PS responses to LC such as changes in muscle activation and prior LC experience.

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 nano-sized heat engine. Simultaneously, the electron temperatures of the reservoirs are affected, resulting in conventional thermoelectric transport. By detailed modelling and experimentally tuning the interdot coupling we disentangle both effects. Furthermore, we show that phonon-assisted transport gives access to the energy of excited states. Our findings demonstrate the versatility of our design to study fluctuations and fundamental nanothermodynamics., 11 pages, 4 figures + SI

Honorary Membership in the Society recognizes individuals who have performed eminent service in the advancement of engineering in motion pictures, television, or in the allied arts and sciences. Such contributions shall represent substantially a lifetime’s work inasmuch as Honorary Membership shall be the supreme accolade of the Society.

The electrical-electrical transfer function (EETF), described in International Telecommunications Union—Radiocommunication (ITU-R) BT.2390–7, offers four variations, which allow high luminance imagery to be tone-mapped to a lower luminance in different ways. This is useful when converting high dynamic range (HDR) encoding spaces or rendering HDR content on screens that have limited performance. However, for some input colors, these variations introduce drastic changes in hue, in some cases, and do not restrict the output to the desired color volume, in other cases. In this article, a fifth variation is proposed, that preserves the input color’s hue while also restricting the output to the specified color volume. This proposed variation is compared and shown to outperform the four standardized variations.

Millions of Americans have learned some form of meditation, including mindfulness, mantra, and spiritual meditation. The majority of them learned on their own, comparatively few consulting a practitioner or attending a meditation class to receive instruction. Despite persistent consumer interest, there is limited research on meditation instruction. As interest in meditation continues to grow, the need for information on instructional best practices becomes increasingly important. For this reason, an instructional resource was developed that provided a simple heuristic for understanding and navigating meditation practice. A consumer-oriented pilot study was conducted to evaluate the resource in terms of perceived benefit, memorability, and satisfaction. The majority of participants reported it to be beneficial for understanding and practicing meditation and were able to recall the four elements of the resource correctly following a 3-week latency period and indicated general satisfaction with the resource. Meditation practice on days using versus not using the resource was also longer. Results suggest that a simple meditation resource can be of benefit in meditation instruction and practice.

International esteem for Galápagos’ natural wonders and the democratization of travel have contributed to a 300% increase in annual tourist entries to the archipelago from 2000 (68,989) to 2018 (275,817). The attendant spike in tourism-related anthropogenic impact coupled with deficient infrastructure development has put the archipelago’s natural capital and carrying capacity at risk. The complex nature of Galápagos’ food insecurity is linked to the archipelago’s geographic isolation, its diminishing agricultural workforce, international tourists’ demand for recognizable food, and a lack of investment in sustainable and innovative agricultural futures. Food security is key to the long-term well-being of Galapagueños, who sustain Galápagos’ tourism industry. However, the COVID-19 pandemic has further exposed the vulnerability of human systems in Galápagos, especially the fragility of Galápagos’ ecotourism dependency. Galapagueños’ struggle to endure the tourism sector’s slow rebound following the 2020 travel restrictions points to an urgent need to implement food security measures as an indispensable component of the archipelago’s long-term sustainability plan. This article presents ethnographic data to discuss the tourism sector’s impact on local food systems, Galapagueños’ right to food sovereignty, efforts to increase agricultural production, and why strengthening institutional partnerships is vital to Galápagos’ food self-sufficiency.

Proposals for quantum information applications are frequently based on the coherent manipulation of spins confined to quantum dots. For these applications, $p$-type III-V material systems promise a reduction of the hyperfine interaction while maintaining large $g$ factors and strong spin-orbit interaction. In this Letter, we study bottom-gated device architectures to realize single and serial multiquantum dot systems in Schottky-contacted $p$-type GaSb nanowires. We find that the effect of potentials applied to gate electrodes on the nanowire is highly localized to the immediate vicinity of the gate electrode only, which prevents the formation of double quantum dots with commonly used device architectures. We further study the transport properties of a single quantum dot induced by bottom gating and find large gate-voltage dependent variations of the ${g}^{*}$ factors up to $8.1\ifmmode\pm\else\textpm\fi{}0.2$ as well as spin-orbit energies between 110 and 230 $\ensuremath{\mu}\mathrm{eV}$.

Colleges and universities have implemented a broad range of initiatives to support student success. Problem solving courses and course supplements are one approach. Evaluation of these courses has shown positive outcomes in terms of improved academic performance and other benefits. A number of these studies have also reported the largest positive effects with underperforming student groups. To further explore this approach a novel general education academic success course was developed. The course integrated a comprehensive problem-solving model into lectures and assignments as the basis of an active learning instructional strategy. Students were taught the model along with relevant academic skills content. They then applied the model to a personal challenge affecting their success in school and life. Using a matched cohort design, 826 course participants were compared with a campus-wide sample matched on key variables. Generalized linear models were used to estimate between group mean differences, and a Cox proportional hazards model was used to compare time to graduation. Results showed that students who successfully completed the course achieved higher cumulative GPAs overall compared with matched peers. Highest GPAs for students who took the course as freshmen suggested a transfer of knowledge over time. Results also showed that the course significantly benefited students from historically at-risk populations in terms of higher GPAs, units earned, retention, and graduation rates. This study shows that a well designed problem solving course can help students, especially those who struggle academically, to more effectively meet the challenges of college and daily life.

Mass spectrometry has established itself as a powerful tool in the chemical, biological, medical, environmental, and agricultural fields. However, experimental approaches and potential application areas have been limited by a traditional reliance on sample preparation, extraction, and chromatographic separation. Ambient ionization mass spectrometry methods have addressed this challenge but are still somewhat restricted in requirements for sample manipulation to make it suitable for analysis. These limitations are particularly restrictive in view of the move toward high-throughput and automated analytical workflows. To address this, we present what we consider to be the first automated sample-preparation-free mass spectrometry platform utilizing a carbon dioxide (CO2) laser for sample thermal desorption linked to the rapid evaporative ionization mass spectrometry (LA-REIMS) methodology. We show that the pulsatile operation of the CO2 laser is the primary factor in achieving high signal-to-noise ratios. We further show that the LA-REIMS automated platform is suited to the analysis of three diverse biological materials within different application areas. First, clinical microbiology isolates were classified to species level with an accuracy of 97.2%, the highest accuracy reported in current literature. Second, fecal samples from a type 2 diabetes mellitus cohort were analyzed with LA-REIMS, which allowed tentative identification of biomarkers which are potentially associated with disease pathogenesis and a disease classification accuracy of 94%. Finally, we showed the ability of the LA-REIMS system to detect instances of adulteration of cooking oil and determine the geographical area of production of three protected olive oil products with 100% classification accuracy.

In process mining, extensive data about an organizational process is summarized by a formal mathematical model with well-grounded semantics. In recent years a number of successful algorithms have been developed that output Petri nets, and other related formalisms, from input event logs, as a way of describing process control flows. Such formalisms are inherently constrained when reasoning about the probabilities of the underlying organizational process, as they do not explicitly model probability. Accordingly, this paper introduces a framework for automatically discovering stochastic process models, in the form of Generalized Stochastic Petri Nets. We instantiate this Toothpaste Miner framework and introduce polynomial-time batch and incremental algorithms based on reduction rules. These algorithms do not depend on a preceding control-flow model. We show the algorithms terminate and maintain a deterministic model once found. An implementation and evaluation also demonstrate feasibility.

Many algorithms now exist for discovering process models from event logs. These models usually describe a control flow and are intended for use by people in analysing and improving real-world organizational processes. The relative likelihood of choices made while following a process (i.e., its stochastic behaviour) is highly relevant information which few existing algorithms make available in their automatically discovered models. This can be addressed by automatically discovered stochastic process models.

Sparse data exist regarding the normal range of composition of maternal milk beyond the first postnatal weeks. This single timepoint, observational study in collaboration with the &lsquo, Parenting Science Gang&rsquo, citizen science group evaluated the metabolite and bacterial composition of human milk from 62 participants (infants aged 3&ndash, 48 months), nearly 3 years longer than previous studies. We utilised rapid evaporative ionisation mass spectrometry (REIMS) for metabolic fingerprinting and 16S rRNA gene metataxonomics for microbiome composition analysis. Milk expression volumes were significantly lower beyond 24 months of lactation, but there were no corresponding changes in bacterial load, composition, or whole-scale metabolomic fingerprint. Some individual metabolite features (~14%) showed altered abundances in nursling age groups above 24 months. Neither milk expression method nor nursling sex affected metabolite and metataxonomic fingerprints. Self-reported lifestyle factors, including diet and physical traits, had minimal impact on metabolite and metataxonomic fingerprints. Our findings suggest remarkable consistency in human milk composition over natural-term lactation. The results add to previous studies suggesting that milk donation can continue up to 24 months postnatally. Future longitudinal studies will confirm the inter-individual and temporal nature of compositional variations and the use of donor milk as a personalised therapeutic.

To determine the possible role of organic matter in promoting the attenuation of an Acid Rock Drainage (ARD), microcosm-based experiments were performed using ARD sediment which had been stimulated by addition of local plants and different manures. Mineralogical, geochemical, organic geochemical and microbial analyses of the ARD sediment, indicated a predominance of goethite, a substantial amount of organic carbon originating from local sources and a bacterial community comparable to those detected in a range of ARD sites worldwide. After one hundred days of incubation, changes in the mineralogical, organic and microbiological composition of the biostimulated ARD sediments, have demonstrated that the plant additions stimulate microbes that have the potential to degrade this organic matter but do not necessary cause substantial Fe(III)-reduction. Conversely, the greatest observed stimulation of Fe(III)-reduction, associated with an increase in pH to near neutral values, was observed using manure additions. These results demonstrate that adding the optimal natural carbon source offers a potential remediation strategy for sites impacted by acid mine or rock drainage, through the stimulation of biogeochemical processes that can generate alkalinity.

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.

We use co-tunneling spectroscopy to investigate spin-, orbital-, and spin-orbital Kondo transport in a strongly confined system of InAs double quantum dots (QDs) parallel-coupled to source and drain. In the one-electron transport regime, the higher symmetry spin-orbital Kondo effect manifests at orbital degeneracy and no external magnetic field. We then proceed to show that the individual Kondo contributions can be isolated and studied separately; either by orbital detuning in the case of spin-Kondo transport, or by spin splitting in the case of orbital Kondo transport. By varying the inter-dot tunnel coupling, we show that lifting of the spin degeneracy is key to confirming the presence of an orbital degeneracy, and to detecting a small orbital hybridization gap. Finally, in the two-electron regime, we show that the presence of a spin-triplet ground state results in spin-Kondo transport at zero magnetic field., 8 pages, 6 figures

Cyclical heat engines are a paradigm of classical thermodynamics, but are impractical for miniaturization because they rely on moving parts. A more recent concept is particle-exchange (PE) heat engines, which uses energy filtering to control a thermally driven particle flow between two heat reservoirs. As they do not require moving parts and can be realized in solid-state materials, they are suitable for low-power applications and miniaturization. It was predicted that PE engines could reach the same thermodynamically ideal efficiency limits as those accessible to cyclical engines, but this prediction has not been verified experimentally. Here, we demonstrate a PE heat engine based on a quantum dot (QD) embedded into a semiconductor nanowire. We directly measure the engine's steady-state electric power output and combine it with the calculated electronic heat flow to determine the electronic efficiency $\eta$. We find that at the maximum power conditions, $\eta$ is in agreement with the Curzon-Ahlborn efficiency and that the overall maximum $\eta$ is in excess of 70$\%$ of the Carnot efficiency while maintaining a finite power output. Our results demonstrate that thermoelectric power conversion can, in principle, be achieved close to the thermodynamic limits, with direct relevance for future hot-carrier photovoltaics, on-chip coolers or energy harvesters for quantum technologies.

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.

The accurate and timely identification of the causative organism of infection is important in ensuring the optimum treatment regimen is prescribed for a patient. Rapid evaporative ionisation mass spectrometry (REIMS), using electrical diathermy for the thermal disruption of a sample, has been shown to provide fast and accurate identification of microorganisms directly from culture. However, this method requires contact to be made between the REIMS probe and microbial biomass; resulting in the necessity to clean or replace the probes between analyses. Here, optimisation and utilisation of ambient laser desorption ionisation (ALDI) for improved speciation accuracy and analytical throughput is shown. Optimisation was completed on 15 isolates of Escherichia coli, showing 5 W in pulsatile mode produced the highest signal-to-noise ratio. These parameters were used in the analysis of 150 clinical isolates from ten microbial species, resulting in a speciation accuracy of 99.4% - higher than all previously reported REIMS modalities. Comparison of spectral data showed high levels of similarity between previously published electrical diathermy REIMS data. ALDI does not require contact to be made with the sample during analysis, meaning analytical throughput can be substantially improved, and further, increases the range of sample types which can be analysed in potential direct-from-sample pathogen detection.

© 2017 Springer Science+Business Media, LLC, part of Springer Nature Chinese Americans have low colorectal cancer (CRC) screening rates. It is unclear whether physicians should offer all CRC screening modalities (fecal occult blood test [FOBT], sigmoidoscopy, colonoscopy) to Chinese Americans to increase screening. Seven hundred and twenty-five Chinese Americans were asked in a survey if their physician had ever recommended CRC screening and to self-report receipt and type of CRC screening. Participants whose physician had recommended all CRC screening modalities were significantly more likely to report ever having screening (adjusted odds ratio 4.29, 95% CI 1.26–14.68) and being up-to-date (4.06, 95% CI 2.13–7.74) than those who reported that their physician only recommended FOBT. Participants who received a recommendation of only one type of screening did not report a significant difference in ever having or being up-to-date for screening. A potential strategy to increase CRC screening among Chinese Americans is for clinicians to recommend all available CRC screening modalities to each patient.

Rapid Evaporative Ionisation 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 handheld bipolar probe allowed REIMS to analyse 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 on the creation of a customised platform which enables automated, high-throughput REIMS analysis, which requires minimal user input and operation; and 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 optimisation of our data analysis approach, we achieved substantially similar results between the two REIMS approaches. For handheld bipolar probe REIMS a speciation accuracy of 96.3% was achieved, whilst 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 pre-analysis preparative steps.

Repeated violent attacks and arson campaigns perpetrated by organized gangs targeted Muslim communities in Rakhine State of Myanmar in 2012 and 2013. The attacks came after decades of tension between the Muslim minority and the Rakhine Buddhist majority. Many Muslims--mainly those often known as Rohingya--in Rakhine State are effectively stateless, having failed to attain any form of citizenship. (1) Campaigns against Muslims in Rakhine State, who make up around one third of the State's overall population of about 3.2 million, (2) have been described by Human Rights Watch as "ethnic cleansing". (3) In 2012, groups of local Rakhine activists razed communities to the ground in central districts of the State as part of a concerted effort to change the area's ethnic composition. Further violent clashes have been attributed to perpetrators from both the minority and majority communities, but reputable sources agree that the main aggressors were affiliated with Rakhine Buddhist networks. (4) Casualty figures are unreliable, but up to 1,000 people, the majority of them Muslim, are thought to have died in inter-communal violence during 2012. In two waves of attacks, most of the Muslims living in central parts of Rakhine State were displaced from their communities and relocated to isolated camps. Their freedom of movement remained restricted after the violence subsided. (5) In most instances, a similar pattern of violence evolved. A specific and emotive flashpoint, such as allegations of offences committed by Muslim men against Rakhine women, was seized as a rallying call for a violent response by groups of mostly young Rakhine men. Tensions remained high and in 2015 most of the 140,000 Muslims who had fled from their homes were still confined to camps. (6) Individuals associated with the 2012 violence appear to have close ties to ethnic Rakhine politicians such as Kyaw Zaw Oo, a political activist who published an outspoken revisionist tract alleging that Muslims in Rakhine State were aliens. Despite having been arrested for his role in the communal violence of 2012, he stood successfully for a parliamentary seat in Sittwe, the capital of Rakhine State in the November 2015 general elections. (7) This article explores the reasons behind the outbreak of violence in Rakhine State in 2012. It considers patterns identified in comparative analyses of communal and ethnic violence, and identifies the main factors that affect this specific case. The research approach uses primary data, consisting mainly of interviews by the author with key informants in Rakhine State and Yangon during several periods in 2013 and 2014. Secondary sources were also consulted, including media coverage, official government statements, reports from humanitarian agencies, online blogs and published academic work. (8) Taken together, these sources cover the circumstances and the wider context of the violence in Rakhine State at that time. The findings also take account of the outcome of the elections of 8 November 2015, an important landmark for politicians in Rakhine State and for all of Myanmar. In addressing the reasons behind ethnic conflicts, researchers have considered specific aspects of violence, focusing on identifiable political and social factors that can be observed across recent conflicts. Empirical studies suggest that the risk of violence is greater among populations with high levels of stratification along ethnic lines whereby certain ethnic groups are more privileged than others. Frances Stewart's work builds on earlier literature addressing multiethnic societies and finds that disparities between ethnic groups or "horizontal inequalities" increase the likelihood of conflict. (9) Michael Mann states that in areas inhabited by different ethnic groups, a high level of nationalism defined along ethnic lines tends to justify extreme standpoints, enable leaders to create scapegoats out of minorities and reduce the scope to manage inter-group tensions. …

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.

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.

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 K2) at low temperatures. However, they have no clear advantage over bulk materials at, or above, room temperature. (Less)

The recently developed automated, high-throughput monopolar REIMS platform is suited for the identification of clinically important microorganisms. Although already comparable to the previously reported bipolar forceps method, optimization of the geometry of monopolar electrodes, at the heart of the system, holds the most scope for further improvements to be made. For this, sharp tip and round shaped electrodes were optimized to maximize species-level classification accuracy. Following optimization of the distance between the sample contact point and tube inlet with the sharp tip electrodes, the overall cross-validation accuracy improved from 77% to 93% in negative and from 33% to 63% in positive ion detection modes, compared with the original 4 mm distance electrode. As an alternative geometry, round tube shaped electrodes were developed. Geometry optimization of these included hole size, number, and position, which were also required to prevent plate pick-up due to vacuum formation. Additional features, namely a metal “X”-shaped insert and a pin in the middle were included to increase the contact surface with a microbial biomass to maximize aerosol production. Following optimization, cross-validation scores showed improvement in classification accuracy from 77% to 93% in negative and from 33% to 91% in positive ion detection modes. Supervised models were also built, and after the leave 20% out cross-validation, the overall classification accuracy was 98.5% in negative and 99% in positive ion detection modes. This suggests that the new generation of monopolar REIMS electrodes could provide substantially improved species level identification accuracies in both polarity detection modes. Graphical abstract Electronic supplementary material The online version of this article (10.1007/s13361-017-1818-5) contains supplementary material, which is available to authorized users.

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.

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.