Construction of semiconductor nanocomposites for room-temperature gas sensors.

Gas sensors are essential for ensuring public safety and improving quality of life. Room-temperature gas sensors are notable for their potential economic benefits and low energy consumption, and their expected integration with wearable electronics, making them a focal point of contemporary research. Advances in nanomaterials and low-dimensional semiconductors have significantly contributed to the enhancement of room-temperature gas sensors. These advancements have focused on improving sensitivity, selectivity, and response/recovery times, with nanocomposites offering distinct advantages. The discussion here focuses on the use of semiconductor nanocomposites for gas sensing at room temperature, and provides a review of the latest synthesis techniques for these materials. This involves the precise adjustment of chemical compositions, microstructures, and morphologies. In addition, the design principles and potential functional mechanisms are examined. This is crucial for deepening the understanding and enhancing the operational capabilities of sensors. We also highlight the challenges faced in scaling up the production of nanocomposite materials. Looking ahead, semiconductor nanocomposites are expected to drive innovation in gas sensor technology due to their carefully crafted design and construction, paving the way for their extensive use in various sectors.

Two-Phase Electrosynthesis of Dihydroxycoumestans: Discovery of a New Scaffold for Topoisomerase I Poison.

Coumestan represents a biologically relevant structural motif distributed in a number of natural products, and the rapid construction of related derivatives as well as the characterization of targets would accelerate lead compound discovery in medicinal chemistry. In this work, a general and scalable approach to 8,9-dihydroxycoumestans via two-electrode constant current electrolysis was developed. The application of a two-phase (aqueous/organic) system plays a crucial role for success, protecting the sensitive o-benzoquinone intermediates from over-oxidation. Based on the structurally diverse products, a primary SAR study on coumestan scaffold was completed, and compound 3 r exhibited potent antiproliferative activities and a robust topoisomerase I (Top1) inhibitory activity. Further mechanism studies demonstrates that compound 3 r was a novel Top1 poison, which might open an avenue for the development of Top1-targeted antitumor agent.

Solution Blow Spinning of the Benzimidazole-Containing Aramid Nanofibers for Separators of Lithium-Ion Batteries.

Nanofibers based on high-performance polymers are much highlighted in recent studies toward advanced lithium-ion batteries. Herein, we demonstrate one scalable poly(ethylene oxide) (PEO)-assisted solution blow spinning strategy for the preparation of heterocyclic aramid (HA) nanofibers of poly(p-phenylene-benzimidazole-terephthalamide). The incorporation of PEO is essential to improve the spinnability of the HA solution achieved directly through the low-temperature-solution copolymerization process. Additionally, the flexible PEO with a strong H-bonding affinity is also utilized as the molecular zipper to adjust the pore size of the nanofiber membrane during the post-treatment process. The obtained membrane combines the good wettability of PEO to the liquid electrolytes, with outstanding mechanical strength, modulus, toughness, and environmental resistance of HA. The nonwoven separator membranes with a porosity of 83.6% exhibited excellent comprehensive performance, which could be seen not only on the high tensile strength (68.2 MPa), modulus (3.0 GPa), and toughness but also on the high thermal stability (Td > 405 °C) and flame retardancy, as well as the high electrolyte uptake (302.4%). The ion conductivity of the porous separators reached 0.83 mS/cm, with the bulk resistance dropping to 1/4 of the reference polypropylene separator. In the assembly of the Li/LiFePO4 half battery, the HA separators displayed improved discharge specific capacity and high retention in both rate capability and cycling tests, providing the potential industrial preparation for advanced lithium-ion batteries.

Long-term observation on safety and visual quality of implantable collamer lens V4c implantation for myopia correction: a 5-year follow-up.

AIM: To elucidate the safety and visual quality of implantable collamer lens with central hole (ICL V4c) implantation for correcting moderate and high myopia for at least 5y. METHODS: This retrospective study was conducted on 58 patients (114 eyes) who were followed up for at least 5y after ICL V4c implantation. The observation was done before and on 1d, 1mo, 1 and 5y or more after the surgical procedure. The visual acuity, subjective refraction, intraocular pressure, vault, axial length, central hole position, pupil diameter, visual quality, and adverse events were analyzed. The visual quality includes aberration, the modulation transfer function cutoff frequency (MTF cutoff), objective scattering index (OSI), Stroller's ratio (SR), and visual quality questionnaire. RESULTS: The average follow-up period was 69.25±3.80mo (range 60-82mo) and the preoperative spherical equivalent (SE) was -8.66±1.97 D. At 5y after operation, the safety index was 1.01±0.02 and the efficacy index was 0.99±0.42 and SE was -0.65±0.63 D. The 59.6% of the eyes achieved an uncorrected distance visual acuity of 20/20, 76.3% of the eyes had SE within ±1.0 D at the last visit. The axial length increased by 0.29±0.71 mm 5y after the surgery (t=-3.843, P<0.001). The mean vault at the last follow-up was 510.59±245.61 µm. The central hole was on the temporal side in 80 eyes (84.2%). The visual quality questionnaire showed that 98.2% patients were satisfied with the surgical procedure. Adverse events occurred in 4 eyes (3.5%), including the posttraumatic toric ICL rotation (2 eyes), iris incarceration (1 eye), and posttraumatic ICL displacement (1 eye) at the last follow-up. CONCLUSION: Long-term ICL V4c implantation is safe, effective, and stable for correcting moderate and to high myopia, and the visual quality with patients is excellent and satisfactory, but the progression of axial length still needs attention after surgery.

A Biterm Topic Model for Sparse Mutation Data.

Mutational signature analysis promises to reveal the processes that shape cancer genomes for applications in diagnosis and therapy. However, most current methods are geared toward rich mutation data that has been extracted from whole-genome or whole-exome sequencing. Methods that process sparse mutation data typically found in practice are only in the earliest stages of development. In particular, we previously developed the Mix model that clusters samples to handle data sparsity. However, the Mix model had two hyper-parameters, including the number of signatures and the number of clusters, that were very costly to learn. Therefore, we devised a new method that was several orders-of-magnitude more efficient for handling sparse data, was based on mutation co-occurrences, and imitated word co-occurrence analyses of Twitter texts. We showed that the model produced significantly improved hyper-parameter estimates that led to higher likelihoods of discovering overlooked data and had better correspondence with known signatures.

A mixture model for signature discovery from sparse mutation data.

Mutational signatures are key to understanding the processes that shape cancer genomes, yet their analysis requires relatively rich whole-genome or whole-exome mutation data. Recently, orders-of-magnitude sparser gene-panel-sequencing data have become increasingly available in the clinic. To deal with such sparse data, we suggest a novel mixture model, Mix. In application to simulated and real gene-panel sequences, Mix is shown to outperform current approaches and yield mutational signatures and patient stratifications that are in higher agreement with the literature. We further demonstrate its utility in several clinical settings, successfully predicting therapy benefit and patient groupings from MSK-IMPACT pan-cancer data. Availability: https://github.com/itaysason/Mix-MMM .

Of dilemmas and tensions: a qualitative study of palliative care physicians' positions regarding voluntary active euthanasia in Quebec, Canada.

OBJECTIVES: In 2015, the Province of Quebec, Canada passed a law that allowed voluntary active euthanasia (VAE). Palliative care stakeholders in Canada have been largely opposed to euthanasia, yet there is little research about their views. The research question guiding this study was the following: How do palliative care physicians in Quebec position themselves regarding the practice of VAE in the context of the new provincial legislation? METHODS: We used interpretive description, an inductive methodology to answer research questions about clinical practice. A total of 18 palliative care physicians participated in semistructured interviews at two university-affiliated hospitals in Quebec. RESULTS: Participants positioned themselves in opposition to euthanasia. Their justifications were framed within their professional commitment to not hasten death, which sat in tension with the value of patients' autonomy to choose how to die. Participants described VAE as unacceptable if it impeded opportunities to evaluate and alleviate suffering. Further, they contested government rhetoric that positioned VAE as a way to improve end-of-life care. Participants felt that VAE would diminish the potential of palliative care to relieve suffering. Dilemmas were apparent in their narratives, about reconciling respect for patient autonomy with broader palliative care values, and the value of accompanying and not abandoning patients who make requests for VAE while being committed to neither prolonging nor hastening death. CONCLUSIONS: This study provides insight into nuanced positions of experienced palliative care physicians in Quebec and confirms expected tensions between an important stakeholder and the practice of VAE as guided by the new legislation.

A Novel Colon Wall Flattening Model for Computed Tomographic Colonography: Method and Validation.

Computed tomographic colonography (CTC) has been developed for screening of colon cancer. Flattening the three-dimensional (3D) colon wall into two-dimensional (2D) image is believed to (1) provide supplementary information to the endoscopic views and further (2) facilitate colon registration, taniae coli (TC) detection, and haustral fold segmentation. Though the previously-used conformal mapping-based flattening methods can preserve the angular geometry, they have the limitations in providing accurate information of the 3D inner colon wall due to the lack of undulating topography. In this paper, we present a novel colon-wall flattening method using a strategy of 2.5D approach. Coupling with the conformal flattening model, the presented new approach builds an elevation distance map to depict the neighborhood characteristics of the inner colon wall. We validated the new method via two CTC applications: TC detection and haustral fold segmentation. Experimental results demonstrated the effectiveness of our strategy for CTC studies.