141 research outputs found

    A Colorimetric Label‐Free Sensor Array of Metal–Organic‐Framework‐Based Fabry–Pérot Films for Detecting Volatile Organic Compounds and Food Spoilage

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    The unambiguous detection and classification of volatile organic compounds (VOCs) are crucial in many fields. For using VOC-sensing to explore the alteration and spoilage of food, very inexpensive sensors are desired. Simple colorimetric sensors seem highly attractive for these applications. Here, a label-free, colorimetric sensor array made of metal-organic-framework-based (MOF-based) Fabry-Pérot (FP) films is presented where the signal read-out is performed either by their optical spectra or by pictures taken with a smartphone camera. Exposing the FP-MOF-films to various VOCs causes a reversible shift of the photonic pattern, where the magnitude of the shift depends on the VOC type, its concentration, and the MOF structure. The application of machine- learning- algorithms on the sensor data allows to identify the VOCs with a high classification accuracy (92% at 100 ppm). It is shown that the sensor array read-out can also be performed with a common smartphone camera, also precisely classifying the VOC analytes. Moreover, fresh and spoiled food, like milk and meat, is distinguished by its head space. Thus, the study presents a very inexpensive platform of small colorimetric sensors that allow determining the quality, alteration, and spoilage of food, and it may contribute to realizing smart labels and intelligent packaging

    Investigating the Impact of Shading Effect on the Characteristics of a Large-Scale Grid-Connected PV Power Plant in Northwest China

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    Northwest China is an ideal region for large-scale grid-connected PV system installation due to its abundant solar radiation and vast areas. For grid-connected PV systems in this region, one of the key issues is how to reduce the shading effect as much as possible to maximize their power generation. In this paper, a shading simulation model for PV modules is established and its reliability is verified under the standard testing condition (STC) in laboratory. Based on the investigation result of a 20 MWp grid-connected PV plant in northwest China, the typical shading phenomena are classified and analyzed individually, such as power distribution buildings shading and wire poles shading, plants and birds droppings shading, and front-row PV arrays shading. A series of experiments is also conducted on-site to evaluate and compare the impacts of different typical shading forms. Finally, some feasible solutions are proposed to avoid or reduce the shading effect of PV system during operation in such region

    Phylogenetic, Expression, and Bioinformatic Analysis of the ABC1

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    We studied 17 ABC1 genes in Populus trichocarpa, all of which contained an ABC1 domain consisting of about 120 amino acid residues. Most of the ABC1 gene products were located in the mitochondria or chloroplasts. All had a conserved VAVK-like motif and a DFG motif. Phylogenetic analysis grouped the genes into three subgroups. In addition, the chromosomal locations of the genes on the 19 Populus chromosomes were determined. Gene structure was studied through exon/intron organization and the MEME motif finder, while heatmap was used to study the expression diversity using EST libraries. According to the heatmap, PtrABC1P14 was highlighted because of the high expression in tension wood which related to secondary cell wall formation and cellulose synthesis, thus making a contribution to follow-up experiment in wood formation. Promoter cis-element analysis indicated that almost all of the ABC1 genes contained one or two cis-elements related to ABA signal transduction pathway and drought stress. Quantitative real-time PCR was carried out to evaluate the expression of all of the genes under abiotic stress conditions (ABA, CdCl2, high temperature, high salinity, and drought); the results showed that some of the genes were affected by these stresses and confirmed the results of promoter cis-element analysis

    PromptStyle: Controllable Style Transfer for Text-to-Speech with Natural Language Descriptions

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    Style transfer TTS has shown impressive performance in recent years. However, style control is often restricted to systems built on expressive speech recordings with discrete style categories. In practical situations, users may be interested in transferring style by typing text descriptions of desired styles, without the reference speech in the target style. The text-guided content generation techniques have drawn wide attention recently. In this work, we explore the possibility of controllable style transfer with natural language descriptions. To this end, we propose PromptStyle, a text prompt-guided cross-speaker style transfer system. Specifically, PromptStyle consists of an improved VITS and a cross-modal style encoder. The cross-modal style encoder constructs a shared space of stylistic and semantic representation through a two-stage training process. Experiments show that PromptStyle can achieve proper style transfer with text prompts while maintaining relatively high stability and speaker similarity. Audio samples are available in our demo page

    An algorithm to predict advanced proximal colorectal neoplasia in Chinese asymptomatic population

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    This study aims to develop and validate a new algorithm that incorporates distal colonoscopic findings to predict advanced proximal neoplasia (APN) in a Chinese asymptomatic population. We collected age, gender, and colonoscopic findings from a prospectively performed colonoscopy study between 2013 and 2015 in a large hospital-based endoscopy unit in Shanghai, China. Eligible subjects were allocated to a derivation group (n = 3,889) and validation group (n = 1,944) by random sampling. A new index for APN and its cut-off level were evaluated from the derivation cohort by binary logistic regression. The model performance was tested in the validation cohort using area under the curve (AUC). Age, gender, and distal finding were found to be independent predictors of APN in the derivation cohort (p < 0.001). Subjects were categorized into Average Risk (AR) and High Risk (HR) based on a cut-off score of 2. The AUC of the derivation and validation cohorts were 0.801 (0.754–0.847) and 0.722 (0.649–0.794), respectively. In the validation cohort, those in the HR group had a 3.57 fold higher risk of APN when compared with the AR group (P < 0.001), requiring 18 (95% CI = 12–28) follow-up colonoscopies to detect 1 APN. This new clinical index is useful to stratify APN risk in Chinese population

    Capability of four sigmoidoscopy-based screening strategies to predict proximal neoplasia in an asymptomatic Chinese population

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    Background and Aim: A proper colonoscopy referral criterion is essential for flexible sigmoidoscopy‐based colorectal cancer screening. We aimed to compare the predictive capability of four existing criteria to detect proximal neoplasia (PN) and advanced proximal neoplasia (APN) in a Chinese population. Methods: Asymptomatic Chinese participants aged 50–75 years, who received screening colonoscopy, were consecutively recruited. The four criteria included (i) UK flexible sigmoidoscopy; (ii) Italian Screening for COlon REctum; (iii) NORwegian Colorectal Cancer Prevention trial; and (iv) US clinical index. The sensitivity, specificity, positive/negative predictive value, and the number of subjects needed to screen (NNS)/refer (NNR) to detect one APN/PN were examined. The area under receiver operating characteristic curve was evaluated. Results: Among 5833 subjects, 749 (12.8%) and 151 (2.6%) cases were found to have PN and APN, respectively. US criteria achieved the highest sensitivity for PN (49%) and APN (66%), while UK criteria attained the highest specificity (93%) for PN/APN. The lowest NNS was required by US criteria for PN (16 vs 19–38) and APN (58 vs 69–86), while the lowest NNR was required by UK criteria for PN (3.2 vs 4.0–4.8) and APN (7 vs 10–16). The receiver operating characteristic of all four criteria was 0.57–0.61 for PN and 0.68–0.70 for APN. Conclusions: Among all the four criteria, US criteria had the highest sensitivity and lowest NNS, while UK criteria achieved the highest specificity and lowest NNR. Their limited discriminatory capability highlighted the need for a new score to predict PN/APN in Chinese populations

    Observation of Orbitally Excited B_s Mesons

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    We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let
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