Effect of polymer-coated urea and tillage on the dynamics of available N and nitrous oxide emission from Gray Luvisols

Two field experiments were conducted to assess the effectiveness of polymer-coated urea (PCU) vs. conventional urea (urea) in minimizing nitrate accumulation in soil and nitrous oxide (N₂O) emission while optimizing available N supply. The trials were located on Dark Gray Luvisols (Typic Cryoboralf) near Beaverlodge, Alberta (2004–2007) and Star City, Saskatchewan (2004–2006), in the north western Canadian Prairies. The treatments comprised of combinations of two tillage systems (conventional and no tillage), the two forms of urea (applied at commercial rates, 50–60 kg N ha⁻¹), and time of application (side-banded in spring or fall). Tillage had little effect on the measured soil variables. Available N at the anthesis growth stage was higher with spring- than fall-banded N in three of four site-years, and with PCU than urea in two site-years. At seeding, nitrate in the soil layers to 60-cm depth, especially the top 15 cm, was mostly higher for fall- than spring-banded treatments but differed less between the forms of urea. Fall application, therefore, has greater potential for gaseous N and leaching losses early in the growing season when crops have low N requirements, and hence is not advisable. Nitrous oxide emission from spring to fall was higher with the fertilized treatments in three of five site-years and not different between fertilized and unfertilized treatments in the other site-years. At Beaverlodge, N₂O loss was low in 2 years and showed few significant treatment effects. At Star City, N₂O loss was 1.5- to 1.7-fold higher from urea than PCU treatments, and up to 1.5-fold lower from spring than fall application. It is concluded that although PCU can increase available N during the growth period and reduce N₂O loss in some years compared with urea, the time of N application had a consistently greater effect than the type of urea in enhancing crop N recovery and reducing N loss to the environment.     

Modeling a Thermoelectric HVAC System for Automobiles

In automobiles thermal energy is used at various energy scales. With regard to reduction of CO₂ emissions, efficient generation of hot and cold temperatures and wise use of waste heat are of paramount importance for car manufacturers worldwide. Thermoelectrics could be a vital component in automobiles of the future. To evaluate the applicability of thermoelectric modules in automobiles, a Modelica model of a thermoelectric liquid–gas heat exchanger was developed for transient simulations. The model uses component models from the object-oriented Modelica library TIL. It was validated based on experimental data of a prototype heat exchanger and used to simulate transient and steady-state behavior. The use of the model within the energy management of an automobile is successfully shown for the air-conditioning system of a car.     

Fast spin-echo MR imaging of the eye

Magnetic resonance imaging of the eye usually includes T2-weighted images both for screening purposes and for characterization of melanoma. Conventional T2-weighted spin-echo (SE) imaging suffers both from long acquisition times and incomplete recovery of the vitreous' signal. A fast SE sequence was therefore compared prospectively with conventional sequences in 29 consecutive patients with lesions of the eye. Fast SE images delineated melanoma and other lesions of the eye from vitreous better than conventional T2-weighted images. Image quality and lesion conspicuity were improved on the fast sequence. Whereas melanoma appeared hypointense to vitreous on both types of images, subretinal effusion was hypointense on fast images and hyperintense on conventional T2-weighted images. Ghosting of the globe, which, however, did not decrease diagnostic value, was more pronounced on fast images. Conventional T2-weighted images may be replaced by fast SE images in MR studies of the eye with a gain in lesion conspicuity and significant time saving.     

Polyclonal stimulation of lymphocytes by macrophages

To analyze the interaction between macrophages and splenic lymphocytes with reference to time and concentration, the Mishell-Dutton system was divided into two experimental steps. Step 1 consisted of the cocultivation of spleen cells with various doses of macrophages for different periods of time, while in step 2 macrophages were removed, spleen cells transferred to fresh petri dishes and cultivated until plaque assay. Cocultivation of spleen cells with high doses of macrophages for 4--8 h markedly enhanced the DNA synthesis and plaque-forming cell (PFC) response of sheep red blood cell-stimulated and unstimulated cultures. A cocultivation longer than 24 h resulted in an inhibition of both DNA synthesis and PFC response of spleen cells. These studies suggest a nonspecific function of macrophages on proliferation and differentiation processes in antibody formation.     

Verteilte RC Nullnetzwerke: Vergleich mit RC Doppel-T-Filtern und Anwendung in selektive Verstärkern

Übersicht Ein RC Doppel-T-Filter (i. allg. unsymmetrisch) wird mit einem verteilten RC Null-Filter (mit exponentieller RC-Leitung) hinsichtlich Form und Steilheit der Spannungsübertragungsfunktion verglichen. Der Einfluß der Belastung mit Wirkwiderständen wird untersucht.Bei der Anwendung verteilter RC Nullnetzwerke im Gegenkopplungszweig eines Verstärkers zur Realisierung eines einfachen Bandpasses ergeben sich Mittenfrequenzen des Durchlaßbandes, die von den Nullfrequenzen der passiven Netzwerke verschieden sind. Die Differenz kann auf Netzwerk-und Verstärkerparameter zurückgeführt werden. Zur Berechnung werden die Ortskurven der Nullnetzwerke angenähert.

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Contents A parallel-T RC filter (asymmetrical in general) is compared with a distributed RC null-filter (exponentially tapered) with regard to form and steepness of the voltage transfer function. The influence of resistive load is investigated.Distributed RC null networks can be connected into the feedback loop of an amplifier in order to realize a simple band pass. The difference between the centre frequency of the pass band and the null frequency of a passive network can be related to the parameters of the network and the amplifier. The transfer loci of null networks are approximated for the calculations.

     

Hydrophilic trans‐Cyclooctenylated Noncanonical Amino Acids for Fast Intracellular Protein Labeling

Introduction of bioorthogonal functionalities (e.g., trans‐cyclooctene‐TCO) into a protein of interest by site‐specific genetic encoding of non‐canonical amino acids (ncAAs) creates uniquely targetable platforms for fluorescent labeling schemes in combination with tetrazine‐functionalized dyes. However, fluorescent labeling of an intracellular protein is usually compromised by high background, arising from the hydrophobicity of ncAAs; this is typically compensated for by hours‐long washout to remove excess ncAAs from the cellular interior. To overcome these problems, we designed, synthesized, and tested new, hydrophilic TCO‐ncAAs. One derivative, DOTCO‐lysine was genetically incorporated into proteins with good yield. The increased hydrophilicity shortened the excess ncAA washout time from hours to minutes, thus permitting rapid labeling and subsequent fluorescence microscopy.     

Monitoring Binding of HIV‐1 Capsid Assembly Inhibitors Using 19F Ligand‐and 15N Protein‐Based NMR and X‐ray Crystallography: Early Hit Validation of a Benzodiazepine Series

The emergence of resistance to existing classes of antiretroviral drugs underlines the need to find novel human immunodeficiency virus (HIV)‐1 targets for drug discovery. The viral capsid protein (CA) represents one such potential target. Recently, a series of benzodiazepine inhibitors was identified via high‐throughput screening using an in vitro capsid assembly assay (CAA). Here, we demonstrate how a combination of NMR and X‐ray co‐crystallography allowed for the rapid characterization of the early hits from this inhibitor series. Ligand‐based ¹⁹F NMR was used to confirm inhibitor binding specificity and reversibility as well as to identify the N‐terminal domain of the capsid (CA_NTD) as its molecular target. Protein‐based NMR (¹H and ¹⁵N chemical shift perturbation analysis) identified key residues within the CA_NTD involved in inhibitor binding, while X‐ray co‐crystallography confirmed the inhibitor binding site and its binding mode. Based on these results, two conformationally restricted cyclic inhibitors were designed to further validate the possible binding modes. These studies were crucial to early hit confirmation and subsequent lead optimization.     

Urinary incontinence in rural older women: prevalence, incidence and remission

OBJECTIVES: To determine the prevalence, incidence, and remission rates of urinary incontinence in a large group of older women over a 6-year time span and to assess factors associated with incontinence incidence and remission. DESIGN: Longitudinal cohort study. SETTING: Two rural counties in Iowa. PARTICIPANTS: 2025 women aged 65 years or older residing in rural Iowa, enrolled in the Iowa 65+ Rural Health Study of EPESE (Establishment of Populations for Epidemiologic Studies of the Elderly) were interviewed in person annually for 6 years; specific responses to queries about urinary incontinence were given at baseline, 3-, and 6-year intervals. MEASUREMENTS: Conditional multivariate logistic regression analysis was done to assess the relationship between incontinence symptoms and various factors previously found to be related to incontinence. RESULTS: The baseline prevalence of urge incontinence was 36.3%, and of stress incontinence it was 40.3%. For urge incontinence, the 3-year incidence and remission rates between the third and sixth years were 28.5% and 22.1%, respectively. For stress incontinence, the 3-year incidence and remission rates between years 3 and 6 were 28.6% and 25.1%, respectively. Seventy-six percent and 84% of women who reported no urge or stress incontinence, respectively, at the baseline interview were continent at both follow-up interviews. The only significant factors related to changes in incontinence status were age, which was associated with an increased incidence of urge incontinence (OR 1.11, P = .017, 95% CI 1.019-1.203), and improvement in activities of daily living, which was associated with a increased remission of urge incontinence (OR 0.50, P = .015, 95% CI 0.28-0.9) CONCLUSION: In some older women, urinary incontinence is a dynamic state, with women moving back and forth along a continuum between continence and incontinence. These results are tempered by limitations of the study, which include its questionnaire design and lack of ability to detect potential treatment effect.     

Development of a new composite flow curve statement

A new composite flow curve statement is presented, which allows good approximation of the flow curve and is suitable for numeric simulations. Without restrictions, it holds over the entire range of validity of a flow curve as a function of plastic strain, plastic strain rate and temperature. Simultaneously, it can be used for any material so that it is well suited for material databases. The number of coefficients used is higher than in other flow curve statements; however, the coefficients are calculated more easily and partially by automatic procedures. The described composite statement can be integrated so that it can be employed in analytical calculations, e.g. of force and power requirements.