Improving the creation of SiV centers in diamond via sub-µs pulsed annealing treatment.

Silicon-vacancy (SiV) centers in diamond are emerging as promising quantum emitters in applications such as quantum communication and quantum information processing. Here, we demonstrate a sub-µs pulsed annealing treatment that dramatically increases the photoluminescence of SiV centers in diamond. Using a silane-functionalized adamantane precursor and a laser-heated diamond anvil cell, the temperature and energy conditions required to form SiV centers in diamond were mapped out via an optical thermometry system with an accuracy of ±50 K and a 1 µs temporal resolution. Annealing scheme studies reveal that pulsed annealing can obviously minimize the migration of SiV centers out of the diamond lattice, and a 2.5-fold increase in the number of emitting centers was achieved using a series of 200-ns pulses at a 50 kHz repetition rate via acousto-optic modulation. Our study provides a novel pulsed annealing treatment approach to improve the efficiency of the creation of SiV centers in diamond.

Nanometer-resolution tracking of single cargo reveals dynein motor mechanisms.

Cytoplasmic dynein is essential for intracellular transport. Despite extensive in vitro characterizations, how the dynein motors transport vesicles by processive steps in live cells remains unclear. To dissect the molecular mechanisms of dynein, we develop optical probes that enable long-term single-particle tracking in live cells with high spatiotemporal resolution. We find that the number of active dynein motors transporting cargo switches stochastically between one and five dynein motors during long-range transport in neuronal axons. Our very bright optical probes allow the observation of individual molecular steps. Strikingly, these measurements reveal that the dwell times between steps are controlled by two temperature-dependent rate constants in which two ATP molecules are hydrolyzed sequentially during each dynein step. Thus, our observations uncover a previously unknown chemomechanical cycle of dynein-mediated cargo transport in living cells.

Noninvasive virtual biopsy using micro-registered optical coherence tomography (OCT) in human subjects.

Histological hematoxylin and eosin-stained (H&E) tissue sections are used as the gold standard for pathologic detection of cancer, tumor margin detection, and disease diagnosis. Producing H&E sections, however, is invasive and time-consuming. While deep learning has shown promise in virtual staining of unstained tissue slides, true virtual biopsy requires staining of images taken from intact tissue. In this work, we developed a micron-accuracy coregistration method [micro-registered optical coherence tomography (OCT)] that can take a two-dimensional (2D) H&E slide and find the exact corresponding section in a 3D OCT image taken from the original fresh tissue. We trained a conditional generative adversarial network using the paired dataset and showed high-fidelity conversion of noninvasive OCT images to virtually stained H&E slices in both 2D and 3D. Applying these trained neural networks to in vivo OCT images should enable physicians to readily incorporate OCT imaging into their clinical practice, reducing the number of unnecessary biopsy procedures.

Knowledge and attitude regarding organ donation among medical students in Hong Kong: a cross-sectional study.

OBJECTIVES: The rate of organ donation in Hong Kong is among the lowest in developed regions. Since medical students will play an important role in counselling patients for organ donation and identifying potential donors in the future, their knowledge, attitudes and action for organ donation are important. This study aims to understand knowledge, attitudes and actions with regard to organ donation among medical students and investigate the factors determining the knowledge and attitudes. DESIGN: A cross-sectional study. SETTING AND PARTICIPANTS: Medical students in Hong Kong were invited to complete a questionnaire. 377 medical students participated in the study. METHODS: The questionnaire assessed their attitudes, knowledge, action of organ donation, belief and perception on organ donation, and other factors. Linear regression analyses and logistic regression were performed to analyse the effect of the variables on knowledge, attitudes and action for organ donation. RESULTS: Almost all medical students (99.5%) held a positive attitude towards organ donation, but only 28.1% have signed up as organ donors. Determinants of knowledge of organ donation included belief in preservation of intact body after death (ß = -0.14, 95% CI = -0.24 to -0.04) and perceived confidence and competence of organ donation discussion (ß = -0.12, 95% CI = -0.22 to -0.02). Predictors of organ donor registration status included knowledge of organ donation (OR=1.03, 95% CI=1.00 to 1.06), perceived convenience of organ donation registration (OR=3.75, 95% CI=1.62 to 8.71), commitment to organ donation (OR=3.81, 95% CI=2.01 to 7.21) and exposure to organ donation (OR=4.28, 95% CI=2.37 to 7.74). CONCLUSIONS: Knowledge is positively associated with organ donation action. The above determinants of organ donation could be emphasised in medical education.

Trends of extreme US weather events in the changing climate.

Trends in extreme 100-y events of temperature and rainfall amounts in the continental United States are estimated, to see effects of climate change. This is a nontrivial statistical problem because climate change effects have to be extracted from "noisy" weather data within a limited time range. We use nonparametric Bayesian methods to estimate the trends of extreme events that have occurred between 1979 and 2019, based on data for temperature and rainfall. We focus on 100-y events for each month in [Formula: see text] geographical areas looking at hourly temperature and 5-d cumulative rainfall. Distribution tail models are constructed using extreme value theory (EVT) and data on 33-y events. This work shows it is possible to aggregate data from spatial points in diverse climate zones for a given month and fit an EVT model with the same parameters. This surprising result means there are enough extreme event data to see the trends in the 41-y record for each calendar month. The yearly trends of the risk of a 100-y high-temperature event show an average 2.1-fold increase over the last 41 y of data across all months, with a 2.6-fold increase for the months of July through October. The risk of high rainfall extremes increases in December and January 1.4-fold, but declines by 22% for the spring and summer months.

Effects of TRAM-34 and minocycline on neuroinflammation caused by diabetic ketoacidosis in a rat model.

INTRODUCTION: Diabetic ketoacidosis (DKA) causes acute and chronic neuroinflammation that may contribute to cognitive decline in patients with type 1 diabetes. We evaluated the effects of agents that reduce neuroinflammation (triarylmethane-34 (TRAM-34) and minocycline) during and after DKA in a rat model. RESEARCH DESIGN AND METHODS: Juvenile rats with DKA were treated with insulin and saline, either alone or in combination with TRAM-34 (40 mg/kg intraperitoneally twice daily for 3 days, then daily for 4 days) or minocycline (45 mg/kg intraperitoneally daily for 7 days). We compared cytokine and chemokine concentrations in brain tissue lysates during DKA among the three treatment groups and in normal controls and diabetic controls (n=9-15/group). We also compared brain inflammatory mediator levels in these same groups in adult diabetic rats that were treated for DKA as juveniles. RESULTS: Brain tissue concentrations of chemokine (C-C) motif ligand (CCL)3, CCL5 and interferon (IFNγ) were increased during acute DKA, as were brain cytokine composite scores. Both treatments reduced brain inflammatory mediator levels during acute DKA. TRAM-34 predominantly reduced chemokine concentrations (chemokine (C-X-C) motif ligand (CXCL-1), CCL5) whereas minocycline had broader effects, (reducing CXCL-1, tumor necrosis factor (TNFα), IFNγ, interleukin (IL) 2, IL-10 and IL-17A). Brain inflammatory mediator levels were elevated in adult rats that had DKA as juveniles, compared with adult diabetic rats without previous DKA, however, neither TRAM-34 nor minocycline treatment reduced these levels. CONCLUSIONS: These data demonstrate that both TRAM-34 and minocycline reduce acute neuroinflammation during DKA, however, treatment with these agents for 1 week after DKA does not reduce long-term neuroinflammation.

Reduced Pneumonia Risk in Advanced Dementia Patients on Careful Hand Feeding Compared With Nasogastric Tube Feeding.

OBJECTIVES: To compare survival and pneumonia risk among hospitalized patients with advanced dementia on nasogastric tube feeding (NGF) vs careful hand feeding (CHF) and to examine outcomes by feeding problem type. DESIGN: Retrospective cohort study. SETTING AND PARTICIPANTS: Advanced dementia patients aged ≥60 years with indication for tube feeding admitted to 2 geriatric convalescent hospitals between January 1, 2015, and June 30, 2019. METHODS: Comparison on the effect of NGF and CHF on survival and pneumonia risk using Kaplan Meier survival analysis and Cox proportional hazards models. RESULTS: Of the 764 patients (mean age 89 years, 61% female, 74% residential care home residents), 464 (61%) were initiated on NGF and 300 (39%) on CHF. The primary feeding problem types were dysphagia (50%), behavioral feeding problem (33%), or both (17%). There was no difference in 1-year survival rate between NGF and CHF groups (36% vs 37%, P = .71) and survival did not differ by feeding problem type. Nasogastric tube feeding was not a significant predictor for survival (adjusted hazard ratio 1.15, 95% CI 0.94-1.39). Among 577 (76%) patients who survived to discharge, pneumonia rates were lower in the CHF group (48% vs 60%, P = .004). After adjusting for cofounders, NGF was a significant risk factor for pneumonia (adjusted hazard ratio 1.41, 95% CI 1.08-1.85). In subgroup analyses, NGF was associated with increased pneumonia risk for patients with both dysphagia and behavioral feeding problem (P = .01) but not in patients with behavioral feeding problem alone (P = .24) or dysphagia alone (P = .30). CONCLUSIONS AND IMPLICATIONS: For advanced dementia patients with feeding problems, there is no difference in survival between NGF and CHF. However, NGF is associated with a higher pneumonia risk, particularly for patients with both dysphagia and behavioral feeding problem. Further research on how the feeding problem type impacts pneumonia risk for patients on NGF is needed.

Reversibly Photoswitching Upconversion Nanoparticles for Super-Sensitive Photoacoustic Molecular Imaging.

Photoacoustic (PA) imaging uses light excitation to generate the acoustic signal for detection and improves tissue penetration depth and spatial resolution in the clinically relevant depth of living subjects. However, strong background signals from blood and pigments have significantly compromised the sensitivity of PA imaging with exogenous contrast agents. Here we report a nanoparticle-based probe design that uses light to reversibly modulate the PA emission to enable photoacoustic photoswitching imaging (PAPSI) in living mice. Such a nanoprobe is built with upconverting nanocrystals and photoswitchable small molecules and can be switched on by NIR light through upconversion to UV energy. Reversibly photoswitching of the nanoprobe reliably removed strong tissue background, increased the contrast-to-noise ratio, and thus improved imaging sensitivity. We have shown that PAPSI can image 0.05 nM of the nanoprobe in hemoglobin solutions and 104 labeled cancer cells after implantation in living mice using a commercial PA imager.

Engineering Bright and Mechanosensitive Alkaline-Earth Rare-Earth Upconverting Nanoparticles.

Upconverting nanoparticles (UCNPs) are an emerging platform for mechanical force sensing at the nanometer scale. An outstanding challenge in realizing nanometer-scale mechano-sensitive UCNPs is maintaining a high mechanical force responsivity in conjunction with bright optical emission. This Letter reports mechano-sensing UCNPs based on the lanthanide dopants Yb3+ and Er3+, which exhibit a strong ratiometric change in emission spectra and bright emission under applied pressure. We synthesize and analyze the pressure response of five different types of nanoparticles, including cubic NaYF4 host nanoparticles and alkaline-earth host materials CaLuF, SrLuF, SrYbF, and BaLuF, all with lengths of 15 nm or less. By combining optical spectroscopy in a diamond anvil cell with single-particle brightness, we determine the noise equivalent sensitivity (GPa/√Hz) of these particles. The SrYb0.72Er0.28F@SrLuF particles exhibit an optimum noise equivalent sensitivity of 0.26 ± 0.04 GPa/√Hz. These particles present the possibility of robust nanometer-scale mechano-sensing.

Addressing personal protective equipment (PPE) decontamination: Methylene blue and light inactivates severe acute respiratory coronavirus virus 2 (SARS-CoV-2) on N95 respirators and medical masks with maintenance of integrity and fit.

OBJECTIVE: The coronavirus disease 2019 (COVID-19) pandemic has resulted in shortages of personal protective equipment (PPE), underscoring the urgent need for simple, efficient, and inexpensive methods to decontaminate masks and respirators exposed to severe acute respiratory coronavirus virus 2 (SARS-CoV-2). We hypothesized that methylene blue (MB) photochemical treatment, which has various clinical applications, could decontaminate PPE contaminated with coronavirus. DESIGN: The 2 arms of the study included (1) PPE inoculation with coronaviruses followed by MB with light (MBL) decontamination treatment and (2) PPE treatment with MBL for 5 cycles of decontamination to determine maintenance of PPE performance. METHODS: MBL treatment was used to inactivate coronaviruses on 3 N95 filtering facepiece respirator (FFR) and 2 medical mask models. We inoculated FFR and medical mask materials with 3 coronaviruses, including SARS-CoV-2, and we treated them with 10 µM MB and exposed them to 50,000 lux of white light or 12,500 lux of red light for 30 minutes. In parallel, integrity was assessed after 5 cycles of decontamination using multiple US and international test methods, and the process was compared with the FDA-authorized vaporized hydrogen peroxide plus ozone (VHP+O3) decontamination method. RESULTS: Overall, MBL robustly and consistently inactivated all 3 coronaviruses with 99.8% to >99.9% virus inactivation across all FFRs and medical masks tested. FFR and medical mask integrity was maintained after 5 cycles of MBL treatment, whereas 1 FFR model failed after 5 cycles of VHP+O3. CONCLUSIONS: MBL treatment decontaminated respirators and masks by inactivating 3 tested coronaviruses without compromising integrity through 5 cycles of decontamination. MBL decontamination is effective, is low cost, and does not require specialized equipment, making it applicable in low- to high-resource settings.

Three-Dimensional Analysis of Particle Distribution on Filter Layers inside N95 Respirators by Deep Learning.

The global COVID-19 pandemic has changed many aspects of daily lives. Wearing personal protective equipment, especially respirators (face masks), has become common for both the public and medical professionals, proving to be effective in preventing spread of the virus. Nevertheless, a detailed understanding of respirator filtration-layer internal structures and their physical configurations is lacking. Here, we report three-dimensional (3D) internal analysis of N95 filtration layers via X-ray tomography. Using deep learning methods, we uncover how the distribution and diameters of fibers within these layers directly affect contaminant particle filtration. The average porosity of the filter layers is found to be 89.1%. Contaminants are more efficiently captured by denser fiber regions, with fibers <1.8 µm in diameter being particularly effective, presumably because of the stronger electric field gradient on smaller diameter fibers. This study provides critical information for further development of N95-type respirators that combine high efficiency with good breathability.

Acute and chronic neuroinflammation is triggered by diabetic ketoacidosis in a rat model.

INTRODUCTION: Cognitive decline is common in patients with type 1 diabetes and has been attributed to the effects of chronic hyperglycemia and severe hypoglycemia. Diabetic ketoacidosis (DKA) has only recently been suspected to be involved in causing cognitive decline. We hypothesized that DKA triggers both acute and chronic neuroinflammation, contributing to brain injury. RESEARCH METHODS AND DESIGN: We measured concentrations of cytokines, chemokines and matrix metalloproteinases (MMP) in serum and brain tissue lysates in juvenile rats during and after DKA (during acute DKA, 24 hours and 7 days after DKA), and compared these to healthy controls and hyperglycemic controls. We also measured cytokine, chemokine and MMP concentrations in serum and brain tissue of adult rats (70 days) that had experienced DKA as juveniles and compared these measurements to those of adult diabetic rats without exposure to DKA. RESULTS: During acute DKA in the juvenile rats, serum concentrations of CCL3, tumor necrosis factor (TNF)-α, interleukin (IL)-1ß and MMP-9 were significantly increased. Serum concentrations of IL-2 and IL-17A increased 7 days after DKA recovery. In brain tissue lysates, concentrations of CCL3, CCL5, interferon (IFN)-γ and MMP-9 were significantly elevated during acute DKA. In adult rats that had DKA as juveniles (28 days previously), serum concentrations of IL-1ß and brain concentrations of IL-10 and IL-12p70 were elevated in comparison to diabetic rats without prior DKA. Composite scores for highly correlated cytokines and chemokines (mean z-scores for IL-10, IL-1ß, TNF-α, IL-17A, IFN-γ, CXCL-1 and CCL5) were also significantly elevated in adult rats with prior DKA. CONCLUSIONS: These data confirm that DKA causes acute systemic inflammation and neuroinflammation in a rat model. Importantly, the neuroinflammatory response triggered by DKA is long-lasting, suggesting the possibility that DKA-induced chronic neuroinflammation could contribute to long-term cognitive decline in individuals with diabetes.

Decontamination of SARS-CoV-2 and Other RNA Viruses from N95 Level Meltblown Polypropylene Fabric Using Heat under Different Humidities.

In March of 2020, the World Health Organization declared a pandemic of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The pandemic led to a shortage of N95-grade filtering facepiece respirators (FFRs), especially surgical-grade N95 FFRs for protection of healthcare professionals against airborne transmission of SARS-CoV-2. We and others have previously reported promising decontamination methods that may be applied to the recycling and reuse of FFRs. In this study we tested disinfection of three viruses, including SARS-CoV-2, dried on a piece of meltblown fabric, the principal component responsible for filtering of fine particles in N95-level FFRs, under a range of temperatures (60-95 °C) at ambient or 100% relative humidity (RH) in conjunction with filtration efficiency testing. We found that heat treatments of 75 °C for 30 min or 85 °C for 20 min at 100% RH resulted in efficient decontamination from the fabric of SARS-CoV-2, human coronavirus NL63 (HCoV-NL63), and another enveloped RNA virus, chikungunya virus vaccine strain 181/25 (CHIKV-181/25), without lowering the meltblown fabric's filtration efficiency.

A Single-Molecule Surface-Based Platform to Detect the Assembly and Function of the Human RNA Polymerase II Transcription Machinery.

Single-molecule detection and manipulation is a powerful tool for unraveling dynamic biological processes. Unfortunately, success in such experiments is often challenged by tethering the biomolecule(s) of interest to a biocompatible surface. Here, we describe a robust surface passivation method by dense polymer brush grafting, based on optimized polyethylene glycol (PEG) deposition conditions, exactly at the lower critical point of an aqueous biphasic PEG-salt system. The increased biocompatibility achieved, compared with PEG deposition in sub-optimal conditions away from the critical point, allowed us to successfully detect the assembly and function of a large macromolecular machine, a fluorescent-labeled multi-subunit, human RNA Polymerase II Transcription Pre-Initiation Complex, on single, promoter-containing, surface-immobilized DNA molecules. This platform will enable probing the complex biochemistry and dynamics of large, multi-subunit macromolecular assemblies, such as during the initiation of human RNA Pol II transcription, at the single-molecule level.

Decontamination of SARS-CoV-2 and other RNA viruses from N95 level meltblown polypropylene fabric using heat under different humidities.

In March of 2020, the World Health Organization declared a pandemic of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The pandemic led to a shortage of N95-grade filtering facepiece respirators (FFRs), especially for protection of healthcare professionals against airborne transmission of SARS-CoV-2. We and others have previously reported promising decontamination methods that may be applied to the recycling and reuse of FFRs. In this study we tested disinfection of three viruses including SARS-CoV-2, dried on a piece of meltblown fabric, the principal component responsible for filtering of fine particles in N95-level FFRs, under a range of temperatures (60-95°C) at ambient or 100% relative humidity (RH) in conjunction with filtration efficiency testing. We found that heat treatments of 75°C for 30 min or 85°C for 20 min at 100% RH resulted in efficient decontamination from the fabric of SARS-CoV-2, human coronavirus NL63 (HCoV-NL63) and chikungunya virus vaccine strain 181 (CHIKV-181), without lowering the meltblown fabric's filtration efficiency.

A scalable method of applying heat and humidity for decontamination of N95 respirators during the COVID-19 crisis.

A lack of N95 Filtering Facepiece Respirators (FFRs) during the COVID-19 crisis has placed healthcare workers at risk. It is important for any N95 reuse strategy to determine the effects that proposed protocols would have on the physical functioning of the mask, as well as the practical aspects of implementation. Here we propose and implement a method of heating N95 respirators with moisture (85°C, 60-85% humidity). We test both mask filtration efficiency and fit to validate this process. Our tests focus on the 3M 1860, 3M 1870, and 3M 8210 Plus N95 models. After five cycles of the heating procedure, all three respirators pass both quantitative fit testing (score of >100) and show no degradation of mask filtration efficiency. We also test the Chen Heng V9501 KN95 and HKYQ N95 finding no degradation of mask filtration efficiency, however even for unheated masks these scored <50 for every fit test. The heating method presented here is scalable from individual masks to over a thousand a day with a single industrial convection oven, making this method practical for local application inside health-care facilities.

Household Materials Selection for Homemade Cloth Face Coverings and Their Filtration Efficiency Enhancement with Triboelectric Charging.

The COVID-19 pandemic is currently causing a severe disruption and shortage in the global supply chain of necessary personal protective equipment (e.g., N95 respirators). The U.S. CDC has recommended use of household cloth by the general public to make cloth face coverings as a method of source control. We evaluated the filtration properties of natural and synthetic materials using a modified procedure for N95 respirator approval. Common fabrics of cotton, polyester, nylon, and silk had filtration efficiency of 5-25%, polypropylene spunbond had filtration efficiency 6-10%, and paper-based products had filtration efficiency of 10-20%. An advantage of polypropylene spunbond is that it can be simply triboelectrically charged to enhance the filtration efficiency (from 6 to >10%) without any increase in pressure (stable overnight and in humid environments). Using the filtration quality factor, fabric microstructure, and charging ability, we are able to provide an assessment of suggested fabric materials for homemade facial coverings.

Can N95 Respirators Be Reused after Disinfection? How Many Times?

The coronavirus disease 2019 (COVID-19) pandemic has led to a major shortage of N95 respirators, which are essential for protecting healthcare professionals and the general public who may come into contact with the virus. Thus, it is essential to determine how we can reuse respirators and other personal protective equipment in these urgent times. We investigated multiple commonly used disinfection schemes on media with particle filtration efficiency of 95%. Heating was recently found to inactivate the virus in solution within 5 min at 70 °C and is among the most scalable, user-friendly methods for viral disinfection. We found that heat (≤85 °C) under various humidities (≤100% relative humidity, RH) was the most promising, nondestructive method for the preservation of filtration properties in meltblown fabrics as well as N95-grade respirators. At 85 °C, 30% RH, we were able to perform 50 cycles of heat treatment without significant changes in the filtration efficiency. At low humidity or dry conditions, temperatures up to 100 °C were not found to alter the filtration efficiency significantly within 20 cycles of treatment. Ultraviolet (UV) irradiation was a secondary choice, which was able to withstand 10 cycles of treatment and showed small degradation by 20 cycles. However, UV can potentially impact the material strength and subsequent sealing of respirators. Finally, treatments involving liquids and vapors require caution, as steam, alcohol, and household bleach all may lead to degradation of the filtration efficiency, leaving the user vulnerable to the viral aerosols.

Single-particle spectroscopy for functional nanomaterials.

Tremendous progress in nanotechnology has enabled advances in the use of luminescent nanomaterials in imaging, sensing and photonic devices. This translational process relies on controlling the photophysical properties of the building block, that is, single luminescent nanoparticles. In this Review, we highlight the importance of single-particle spectroscopy in revealing the diverse optical properties and functionalities of nanomaterials, and compare it with ensemble fluorescence spectroscopy. The information provided by this technique has guided materials science in tailoring the synthesis of nanomaterials to achieve optical uniformity and to develop novel applications. We discuss the opportunities and challenges that arise from pushing the resolution limit, integrating measurement and manipulation modalities, and establishing the relationship between the structure and functionality of single nanoparticles.