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•We report 10% polarization in nitrous oxide, a source of long-lived singlet state.•Temperature-induced clusters in N2O/solvent/radical mixture enhance polarization.•Our ab initio ...analytical model of the NMR spectrum provides instant 15N polarimetry.
Dynamic nuclear polarization (DNP) of 15N2O, known for its long-lived singlet-state order at low magnetic field, is demonstrated in organic solvent/trityl mixtures at ∼1.5K and 5T. Both 15N polarization and intermolecular dipolar broadening are strongly affected by the sample’s thermal history, indicating spontaneous formation of N2O clusters. In situ 15N NMR reveals four distinct powder-pattern spectra, attributed to the chemical-shift anisotropy (CSA) tensors of the two 15N nuclei, further split by the intramolecular dipolar coupling between their magnetic moments. 15N polarization is estimated by fitting the free-induction decay (FID) signals to the analytical model of four single-quantum transitions. This analysis implies (10.2±2.2)% polarization after 37h of DNP, and provides a direct, instantaneous probe of the absolute 15N polarization, without a need for time-consuming referencing to a thermal-equilibrium NMR signal.
Coccidioidomycosis in dogs and cats: a review Graupmann-Kuzma, Angela; Valentine, Beth A; Shubitz, Lisa F ...
The Journal of the American Animal Hospital Association,
09/2008, Letnik:
44, Številka:
5
Journal Article
Recenzirano
The dimorphic fungi Coccidioides immitis and Coccidioides posadasii are the causative agents of coccidioidomycosis. Dogs and cats residing in and visiting endemic areas are at risk of exposure to ...infectious arthrospores. The primary infection is pulmonary and frequently results in chronic cough. Disseminated disease is common and causes cutaneous, osseous, cardiac, ocular, nervous system, or other organ disease. Radiographic changes include a variable degree of interstitial pulmonary infiltration, hilar lymphadenopathy, and osseous lesions. Serological titers support the diagnosis, but definitive diagnosis relies on identification of Coccidioides in cytological or tissue samples. Coccidioidomycosis should be considered in any dog or cat that has been potentially exposed during the previous 3 years and is presented with chronic illness, respiratory signs, lameness, lymphadenopathy, nonhealing cutaneous lesions, or neurological, ocular, or cardiac abnormalities.
We present the results from a study of heat transfer enhancement for bulk water boiling at atmospheric pressure on a surface with micro- and nanorelief, including a relief formed from silicon carbide ...and aluminum oxide nanoparticles. Horizontally oriented steel tube 1.2 mm in diameter and copper plate 15 × 3 mm in size were selected as test sections. The process was recorded by means of a video camera, and the values of heat transfer, critical heat fluxes, and contact angles were measured. The use of surface with micro- and nanorelief makes it possible to obtain a significantly higher critical heat flux and boiling heat transfer coefficient owing to a change of surface wettability. The results of investigations can find use in compact heat exchangers, refrigerating plants, heat pipes, in the mirrors of high-capacity lasers, in the targets and resonators of charged particle accelerators and for external cooling of reactor vessels under emergency conditions.
Dynamic nuclear polarization (DNP) of 15N2O15N2O, known for its long-lived singlet-state order at low magnetic field, is demonstrated in organic solvent/trityl mixtures at a141.5 K and 5 T. Both ...15N15N polarization and intermolecular dipolar broadening are strongly affected by the sampleas thermal history, indicating spontaneous formation of N2O clusters. In situ 15N15N NMR reveals four distinct powder-pattern spectra, attributed to the chemical-shift anisotropy (CSA) tensors of the two 15N nuclei, further split by the intramolecular dipolar coupling between their magnetic moments. 15N15N polarization is estimated by fitting the free-induction decay (FID) signals to the analytical model of four single-quantum transitions. This analysis implies (10.2A-2.2)%(10.2A-2.2)% polarization after 37 h of DNP, and provides a direct, instantaneous probe of the absolute 15N15N polarization, without a need for time-consuming referencing to a thermal-equilibrium NMR signal.
Abstract Prior studies have found that > 50% of prehospital intravenous catheters (i.v.s) were unutilized for treatment; however, few data are available regarding which patients benefit. The ...objective of this study was to examine the association between i.v. utilization in the field, paramedic primary impression, and patient presentation. Prehospital records for 34,585 patients were evaluated for i.v. placement and utilization in the field. Logistic regression was used to evaluate the association of primary impression, systolic blood pressure, heart rate, respiratory rate, Glasgow Coma Scale score, skin sign color, and capillary refill with placement and utilization. Intravenous catheters were placed in 60% of patients, but only 17% of the total was utilized. Examples of primary impressions with frequent initiation and low utilization (n = number in group, % of total with i.v. placed, % of total used): post-seizure (n = 989, 72%, 9%); weakness/dizzy/nausea (n = 3092, 69%, 20%), syncope/near-syncope (n = 2034, 81%, 26%), and abdominal pain (n = 1554, 70%, 14%). Fifty-eight percent with normal vital signs received an i.v. and 28–30% were utilized; hypotension: 80% received i.v. (odds ratio OR 1.211, p = 0.012), 70% utilized; hypertension: 61% received i.v. (OR 1.060, p = 0.027), 28% utilized; bradycardia: 82% received i.v. (OR 1.588, p < 0.0001), 51% utilized; tachycardia: 66% received i.v. (OR 1.152, p = 0.001), 33% utilized; bradypnea: 93% received i.v. (OR 1.638, p = 0.051), 86% utilized; tachypnea: 70% (OR 1.120, p = 0.024), 33% utilized. A Glasgow Coma Scale score < 15: 76% received i.v. (OR 1.672, p < 0.0001), 32% utilized. Abnormal skin color: 79% received i.v. (OR 1.691, p < 0.0001), 42% utilized. Certain primary impressions are associated with high i.v. initiation rates but infrequent utilization. High utilization rates were associated with hypotension, bradycardia, bradypnea, and abnormal skin signs. Study of high-frequency, low-utilization groups could reduce unnecessary i.v. placement.
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