Aerosol–Ice Formation Closure Knopf, D. A.; Barry, K. R.; Brubaker, T. A. ...
Bulletin of the American Meteorological Society,
10/2021, Letnik:
102, Številka:
10
Journal Article
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Prediction of ice formation in clouds presents one of the grand challenges in the atmospheric sciences. Immersion freezing initiated by ice-nucleating particles (INPs) is the dominant pathway of ...primary ice crystal formation in mixed-phase clouds, where supercooled water droplets and ice crystals coexist, with important implications for the hydrological cycle and climate. However, derivation of INP number concentrations from an ambient aerosol population in cloud-resolving and climate models remains highly uncertain. We conducted an aerosol–ice formation closure pilot study using a field-observational approach to evaluate the predictive capability of immersion freezing INPs. The closure study relies on collocated measurements of the ambient size-resolved and single-particle composition and INP number concentrations. The acquired particle data serve as input in several immersion freezing parameterizations, which are employed in cloud-resolving and climate models, for prediction of INP number concentrations. We discuss in detail one closure case study in which a front passed through the measurement site, resulting in a change of ambient particle and INP populations. We achieved closure in some circumstances within uncertainties, but we emphasize the need for freezing parameterization of potentially missing INP types and evaluation of the choice of parameterization to be employed. Overall, this closure pilot study aims to assess the level of parameter details and measurement strategies needed to achieve aerosol–ice formation closure. The closure approach is designed to accurately guide immersion freezing schemes in models, and ultimately identify the leading causes for climate model bias in INP predictions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The California Air Resources Board conducted ambient air monitoring of pesticides in support of the California Department of Pesticide Regulation toxic air contaminant program. Monitoring was done in ...several communities in a county of high use during the month of expected peak use of a particular pesticide in order to assess general population exposure. Additional sampling was conducted adjacent to specific agricultural applications to assess maximum short-term concentrations to which the public might be exposed. Medium and low volume samplers were used with appropriate collection media (e.g., Teflon filters, XAD-2 adsorbent resin), followed by laboratory analysis. Concentrations measured around specific applications would be expected to be representative of other areas, especially in California, with comparable application rates, crops, and weather conditions. Since the program began in 1986, monitoring has been conducted for 22 pesticides. Results for three soil fumigants were of potential public health concern and led to the suspension of permits for the use of one pesticide and were used in the development of use modifications and buffer zones for two others.
Diatoms are of interest to the materials research community because of their ability to create highly complex and intricate silica structures under physiological conditions: what these single-cell ...organisms accomplish so elegantly in nature requires extreme laboratory conditions to duplicate-this is true for even the simplest of structures. Following the identification of polycationic peptides from the diatom Cylindrotheca fusiformis, simple silica nanospheres can now be synthesized in vitro from silanes at nearly neutral pH and at ambient temperatures and pressures. Here we describe a method for creating a hybrid organic/inorganic ordered nanostructure of silica spheres through the incorporation of a polycationic peptide (derived from the C. fusiformis silaffin-1 protein) into a polymer hologram created by two-photon-induced photopolymerization. When these peptide nanopatterned holographic structures are exposed to a silicic acid, an ordered array of silica nanospheres is deposited onto the clear polymer substrate. These structures exhibit a nearly fifty-fold increase in diffraction efficiency over a comparable polymer hologram without silica. This approach, combining the ease of processability of an organic polymer with the improved mechanical and optical properties of an inorganic material, could be of practical use for the fabrication of photonic devices.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Precision measurements are reported of the cross-spectrum of rotationally induced differential position displacements in a pair of colocated 39 m long, high-power Michelson interferometers. One arm ...of each interferometer is bent 90° near its midpoint to obtain sensitivity to rotations about an axis normal to the plane of the instrument. The instrument achieves quantum-limited sensing of spatially correlated signals in a broad frequency band extending beyond the 3.9-MHz inverse light travel time of the apparatus. For stationary signals with bandwidth Δ f > 10 kHz , the sensitivity to rotation-induced strain h of classical or exotic origin surpasses CSDδh< t P / 2 , where t P = 5.39 × 10−44 s is the Planck time. This measurement is used to constrain a semiclassical model of nonlocally coherent rotational degrees of freedom of spacetime, which have been conjectured to emerge in holographic quantum geometry but are not present in a classical metric.
Gemcitabine plus cisplatin (GC) and methotrexate, vinblastine, doxorubicin, and cisplatin (MVAC) were compared in patients with locally advanced or metastatic transitional-cell carcinoma (TCC) of the ...urothelium.
Patients with stage IV TCC and no prior systemic chemotherapy were randomized to GC (gemcitabine 1,000 mg/m2 days 1, 8 and 15; cisplatin 70 mg/m2 day 2) or standard MVAC every 28 days for a maximum of six cycles.
Four hundred five patients were randomized (GC, n = 203; MVAC, n = 202). The groups were well-balanced with respect to prognostic factors. Overall survival was similar on both arms (hazards ratio HR, 1.04; 95% confidence interval CI, 0.82 to 1.32; P = .75), as were time to progressive disease (HR, 1.05; 95% CI, 0.85 to 1.30), time to treatment failure (HR, 0.89; 95% CI 0.72 to 1.10), and response rate (GC, 49%; MVAC, 46%). More GC patients completed six cycles of therapy, with fewer dose adjustments. The toxic death rate was 1% on the GC arm and 3% on the MVAC arm. More GC than MVAC patients had grade 3/4 anemia (27% v 18%, respectively), and thrombocytopenia (57% v 21%, respectively). On both arms, the RBC transfusion rate was 13 of 100 cycles and grade 3/4 hemorrhage or hematuria was 2%; the platelet transfusion rate was four patients per 100 cycles and two patients per 100 cycles on GC and MVAC, respectively. More MVAC patients, compared with GC patients, had grade 3/4 neutropenia (82% v 71%, respectively), neutropenic fever (14% v 2%, respectively), neutropenic sepsis (12% v 1%, respectively), and grade 3/4 mucositis (22% v 1%, respectively) and alopecia (55% v 11%, respectively). Quality of life was maintained during treatment on both arms; however, more patients on GC fared better regarding weight, performance status, and fatigue.
GC provides a similar survival advantage to MVAC with a better safety profile and tolerability. This better-risk benefit ratio should change the standard of care for patients with locally advanced and metastatic TCC from MVAC to GC.
Clathrin-mediated endocytosis (CME) regulates many cell physiological processes such as the internalization of growth factors and receptors, entry of pathogens, and synaptic transmission. Within the ...endocytic network, clathrin functions as a central organizing platform for coated pit assembly and dissociation via its terminal domain (TD). We report the design and synthesis of two compounds named pitstops that selectively block endocytic ligand association with the clathrin TD as confirmed by X-ray crystallography. Pitstop-induced inhibition of clathrin TD function acutely interferes with receptor-mediated endocytosis, entry of HIV, and synaptic vesicle recycling. Endocytosis inhibition is caused by a dramatic increase in the lifetimes of clathrin coat components, including FCHo, clathrin, and dynamin, suggesting that the clathrin TD regulates coated pit dynamics. Pitstops provide new tools to address clathrin function in cell physiology with potential applications as inhibitors of virus and pathogen entry and as modulators of cell signaling.
Display omitted
► Identification of selective clathrin inhibitors termed pitstop 1 and pitstop 2 ► Ligand association of clathrin terminal domain regulates coated pit dynamics ► Acute clathrin inhibition blocks HIV entry and synaptic vesicle recycling ► Wide potential biomedical applications of pitstops and derivatives
Abstract
Species radiations, despite immense phenotypic variation, can be difficult to resolve phylogenetically when genetic change poorly matches the rapidity of diversification. Genomic potential ...furnished by palaeopolyploidy, and relative roles for adaptation, random drift and hybridisation in the apportionment of genetic variation, remain poorly understood factors. Here, we study these aspects in a model radiation,
Syzygium
, the most species-rich tree genus worldwide. Genomes of 182 distinct species and 58 unidentified taxa are compared against a chromosome-level reference genome of the sea apple,
Syzygium grande
. We show that while
Syzygium
shares an ancient genome doubling event with other Myrtales, little evidence exists for recent polyploidy events. Phylogenomics confirms that
Syzygium
originated in Australia-New Guinea and diversified in multiple migrations, eastward to the Pacific and westward to India and Africa, in bursts of speciation visible as poorly resolved branches on phylogenies. Furthermore, some sublineages demonstrate genomic clines that recapitulate cladogenetic events, suggesting that stepwise geographic speciation, a neutral process, has been important in
Syzygium
diversification.
Herein, we report further improvements to the synthesis of tenofovir 1, the precursor to tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide fumarate (TAF). Starting from acyclic precursor ...diaminomalononitrile 12, a four-step protocol to tenofovir 1 will allow for vertical integration for more manufacturers. The key transformation is a convergent one-step procedure from 6 as compared to the current commercial process, with an improved yield from 59% (two steps) to 70%. Further improvements include eliminating the need for problematic magnesium tert-butoxide (MTB) and significant solvent reduction by avoiding an intermediate workup. With the costs of HIV/AIDS treatments remaining a barrier for those most in need, lowering the raw material/processing costs and increasing the security of supply can increase patient access.
Microplastic particles are of increasing environmental concern due to the widespread uncontrolled degradation of various commercial products made of plastic and their associated waste disposal. ...Recently, common technology used to repair sewer pipes was reported as one of the emission sources of airborne microplastics in urban areas. This research presents results of the multi-modal comprehensive chemical characterization of the microplastic particles related to waste discharged in the pipe repair process and compares particle composition with the components of uncured resin and cured plastic composite used in the process. Analysis of these materials employs complementary use of surface-enhanced Raman spectroscopy, scanning transmission X-ray spectro-microscopy, single particle mass spectrometry, and direct analysis in real-time high-resolution mass spectrometry. It is shown that the composition of the relatively large (100 μm) microplastic particles resembles components of plastic material used in the process. In contrast, the composition of the smaller (micrometer and sub-micrometer) particles is significantly different, suggesting their formation from unintended polymerization of water-soluble components occurring in drying droplets of the air-discharged waste. In addition, resin material type influences the composition of released microplastic particles. Results are further discussed to guide the detection and advanced characterization of airborne microplastics in future field and laboratory studies pertaining to sewer pipe repair technology.
Microplastic particles are of increasing environmental concern due to the widespread uncontrolled degradation of various commercial products made of plastic and their associated waste disposal.
A low-cost, protecting group-free route to 6-(2-fluoro-4-nitrophenyl)-2-oxa-6-azaspiro3.3heptane (1), the starting material for the in-development tuberculosis treatment TBI-223, is described. The ...key bond forming step in this route is the creation of the azetidine ring through a hydroxide-facilitated alkylation of 2-fluoro-4-nitroaniline (2) with 3,3-bis(bromomethyl)oxetane (BBMO, 3). After optimization, this ring formation reaction was demonstrated at 100 g scale with isolated yield of 87% and final product purity of >99%. The alkylating agent 3 was synthesized using an optimized procedure that starts from tribromoneopentyl alcohol (TBNPA, 4), a commercially available flame retardant. Treatment of 4 with sodium hydroxide under Schotten–Baumann conditions closed the oxetane ring, and after distillation, 3 was recovered in 72% yield and >95% purity. This new approach to compound 1 avoids the previous drawbacks associated with the synthesis of 2-oxa-6-azaspiro3,3heptane (5), the major cost driver used in previous routes to TBI-223. The optimization and multigram scale-up results for this new route are reported herein.
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