Although the Hammerhead ribozyme (HHRz) has long been used as a model system in the field of ribozyme enzymology, several details of its mechanism are still not well understood. In particular, ...significant questions remain concerning the disposition and role of catalytic metals in the HHRz. Previous metal-rescue experiments using a "minimal" HHRz resulted in prediction of a catalytic metal that is bound in the A9/G10.1 site in the ground state of the reaction and that bridges to the scissile phosphate further along the reaction pathway. "Native" or extended HHRz constructs contain tertiary contacts that stabilize a more compact structure at moderate ionic strength. We performed Cd(2+) rescue experiments on an extended HHRz from Schistosoma mansoni using stereo-pure scissile phosphorothioate-substituted substrates in order to determine whether a metal ion makes contact with the scissile phosphate in the ground state or further along the reaction coordinate. Inhibition in Ca(2+)/Mg(2+) and rescue by thiophilic Cd(2+) was specific for the R(p)-S stereoisomer of the scissile phosphate. The affinity of the rescuing Cd(2+), measured in two different ionic strength backgrounds, increased fourfold to 17-fold when the pro-R(p) oxygen is replaced by sulfur. These data support a model in which the rescuing metal ion makes a ground-state interaction with the scissile phosphate in the native HHRz. The resulting model for Mg(2+) activation in the HHRz places a metal ion in contact with the scissile phosphate, where it may provide ground-state electrostatic activation of the substrate.
The surface properties of aluminum, such as chemical composition, roughness, friction, adhesion, and wear, can play an important role in the performance of micro-/nano-electromechanical systems, ...e.g., digital micromirror devices. Aluminum substrates chemically reacted with octadecylphosphonic acid (ODP/Al), decylphosphonic acid (DP/Al), and octylphosphonic acid (OP/Al) have been investigated and characterized by X-ray photoelectron spectroscopy (XPS), contact angle measurements, and atomic force microscopy (AFM). XPS analysis confirmed the presence of alkylphosphonate molecules on ODP/Al, DP/Al, and OP/Al. No phosphonates were found on bare Al as a control. The sessile drop static contact angle of pure water on ODP/Al and DP/Al was typically more than 115° and on OP/Al typically less than 105° indicating that all phosphonic acid reacted Al samples were highly hydrophobic. The root-mean-square surface roughness for ODP/Al, DP/Al, OP/Al, and bare Al was less than 15 nm as determined by AFM. The surface energy for ODP/Al and DP/Al was determined to be approximately 21 and 22 mJ/m2, respectively, by the Zisman plot method, compared to 25 mJ/m2 for OP/Al. ODP/Al and OP/Al were studied by friction force microscopy, a derivative of AFM, to better understand their micro-/nano-tribological properties. ODP/Al gave the lowest coefficient of friction values while bare Al gave the highest. The adhesion forces for ODP/Al and OP/Al were comparable.
The European System for Cardiac Operative Risk Evaluation (EuroSCORE) is the most rigorously evaluated scoring system in cardiac surgery. We sought to evaluate the performance of EuroSCORE in the ...prediction of long-term mortality in patients undergoing heart valve surgery.
Medical records of patients with isolated or combined heart valve surgery, who were discharged alive (n = 1035), were retrospectively reviewed. Their operative surgical risks were calculated according to EuroSCORE model (standard and logistic). Long-term survival data (mean follow-up 4.5 ± 3.1 years) were obtained from the National Death Index. Kaplan-Meier curves of the quartiles of standard and logistic EuroSCORE were plotted.
The estimated 5-year survival rates of the quartiles in the standard and logistic EuroSCORE model were: 90.0% ± 2.3%, 85.1% ± 2.3%, 64.8% ± 3.3%, and 55.1% ± 3.7% (
p < 0.0001, log-rank test with adjustment for trend) and 90.4% ± 2.2%, 86.4% ± 2.5%, 66.9% ± 3.3%, and 56.1% ± 3.3% (
p < 0.0001, log-rank test with adjustment for trend) respectively. The odds of death in the highest-risk quartile were 7.46- and 7.82-fold higher than the odds of death in the lowest-risk quartile for standard and logistic EuroSCORE respectively.
EuroSCORE can be used to predict not only in-hospital mortality, for which it was originally designed, but also long-term mortality in the whole context of heart valve surgery. This outcome can be predicted using the standard EuroSCORE, which is very simple and easy in its calculation.
Citrus sinensis, commonly known as sweet orange, is rich in antioxidants and widely produced worldwide. Sweet orange consists of the water-soluble vitamins C, B1, B2, essential oils, and phenolic ...components. This fruit is known for its health benefits such as immune booster, digestive aid, anticancer activity, and cardioprotective activity. Its shelf life is low and also it contains high moisture content and so drying of oranges can be done. This review compared the following drying methods: sun drying, spray drying, freeze-drying, microwave drying, inert fluidized bed drying, ultrasonic drying, and infrared drying. Both thermal and nonthermal drying techniques had an influence on the functional properties of the dried orange powder. The comparison of the drying techniques determined relationship between the temperature of the drying process and its subsequent changes on the orange components. At higher drying temperature, it was reported to have a lower color, higher browning effect, lower total phenol content, lower total flavonoid content, and lowered antioxidant activity in dried orange samples. Further studies should be done to determine a method for drying oranges which provides high yield with low power consumption, temperature, and cost.
Objectives To compare the direct costs of the index hospitalization and 30-day morbidity and mortality incurred during robotic and conventional coronary artery bypass grafting at a single institution ...based on hospital clinical and financial records. Design Retrospective study, propensity-matched groups with one-to-one nearest neighbor matching. Setting University hospital, a tertiary care center. Participants Two thousand eighty-eight consecutive patients who underwent primary coronary artery bypass grafting (CABG) from January 2007 to March 2012. Interventions One hundred forty-one matched pairs were created and analyzed. Measurements and Main Results Robotic CABG was associated with a decrease in operative time (5.61±1.1 v 6.6±1.15 hours, p<0.001), a lower need for blood transfusion (12.8% v 22.6%, p = 0.04), a shorter length of stay (6 4-9) v 7 5-11 days, p = 0.001), a shorter ICU stay (31 24-49 hours v 52 32-96.5 hours, p<0.001) and lower NY state complications composite rate (4.26% v 13.48%, p = 0.01). In spite of that, the cost of robotic procedures was not significantly different from matched conventional cases ($18,717.35 11,316.1-34,550.6 versus $18,601 13,137-50,194.75, p = 0.13), except 26 hybrid coronary revascularizations in which angioplasty was performed on the same admission (hybrid 25,311.1 18,537.1-41,167.85 versus conventional 18,966.13 13,337.75-56,021.75, p = 0.02). Conclusion Robotically assisted CABG does not increase the cost of the index hospitalization when compared to conventional CABG unless hybrid revascularization is performed on the same admission.
Precipitation-hardened Cu-0.804Cr-0.063Zr alloy is a potential material to be used for the fabrication of heat sinks in International Thermonuclear Experimental Reactor (ITER) applications. The ...softening temperature of these alloys is 500 °C, which makes it suitable for the fabrication of components subjected to high heat flux. During welding, the precipitates get completely dissolved in the melted zone, which results in lower hardness and softening temperature. The aim of this study was to understand the effects of electron beam welding (EBW) on weld bead geometry and mechanical properties of this alloy. Accelerating voltage, beam current, welding speed, and focusing distance were selected as input variables, and bead geometric parameters like bead width, bead penetration, and microhardness values of the fusion and heat-affected zones were considered as outputs. Statistical regression analysis was conducted to determine input-output relationships. All the above input parameters were found to have significant contributions toward bead penetration and microhardness of fusion zone. However, accelerating voltage did not have significant contribution toward bead width. Optimization was done to obtain minimum weldment area after satisfying the conditions of maximum bead penetration and minimum deviation of the hardness of fusion zone from that of parent material. This constrained optimization problem was solved using a genetic algorithm along with a penalty function approach for handling the functional constraints. A good agreement was obtained between the results predicted by the optimization tool and that of real experiments. Thus, the genetic algorithm (GA) could accurately establish input-output relationships of this process.
Self-assembled monolayer (SAM) films have been formed on oxidized copper (Cu) substrates by reaction with 1H,1H,2H,2H-perfluorodecylphosphonic acid (PFDP), octadecylphosphonic acid (ODP), ...decylphosphonic acid (DP), and octylphosphonic acid (OP) and then investigated by X-ray photoelectron spectroscopy (XPS), contact angle measurement (CAM), and atomic force microscopy (AFM). The presence of alkyl phosphonate molecules, PFDP, ODP, DP, and OP, on Cu were confirmed by CAM and XPS analysis. No alkyl phosphonate molecules were seen by XPS on unmodified Cu as a control. The PFDP/Cu and ODP/Cu SAMs were found to be very hydrophobic having water sessile drop static contact angles of more than 140°, while DP/Cu and OP/Cu have contact angles of 119° and 76°, respectively. PFDP/Cu, ODP/Cu, DP/Cu, and OP/Cu SAMs were studied by friction force microscopy, a derivative of AFM, to better understand their micro/nanotribological properties. PFDP/Cu, ODP/Cu, and DP/Cu had comparable adhesive force, which is much lower than that for unmodified Cu. ODP/Cu had the lowest friction coefficient followed by PFDP/Cu, DP/Cu, and OP/Cu while unmodified Cu had the highest. XPS data gives some indication that a bidentate bond forms between the alkyl phosphonate molecules and the oxidized Cu surface. Hydrophobic phosphonate SAMs could be useful as corrosion inhibitors in micro/nanoelectronic devices and/or as promoters for anti-wetting, low adhesion surfaces.
Increasingly, forest management goals include building or maintaining resistance and/or resilience to disturbances in the face of climate change. Although a multitude of descriptive definitions for ...resistance and resilience exist, to evaluate whether specific management activities (silviculture) are effective, prescriptive characterizations are necessary. We introduce a conceptual framework that explicitly differentiates resistance and resilience, denotes appropriate scales, and establishes the context for evaluation-structure and composition. Generally, resistance is characterized as the influence of structure and composition on disturbance, whereas resilience is characterized as the influence of disturbance on subsequent structure and composition. Silvicultural utility of the framework is demonstrated by describing disturbance-specific, time-bound structural and compositional objectives for building resistance and resilience to two fundamentally different disturbances: wildfires and spruce beetle outbreaks. The conceptual framework revealed the crucial insight that attempts to build stand or landscape resistance to spruce beetle outbreaks will ultimately be unsuccessful. This frees the silviculturist to focus on realistic goals associated with building resilience to likely inevitable outbreaks. Ultimately, because structure and composition, at appropriate scales, are presented as the standards for evaluation and manipulation, the framework is broadly applicable to many kinds of disturbance in various forest types.
Methods to map small-molecule binding sites on cellular RNAs are important for understanding interactions with both endogenous and exogenous compounds. Pt(ii) reagents are well-known DNA and RNA ...crosslinking agents, but sequence-specific and genome-wide identification of Pt targets following in-cell treatment is challenging. Here we describe application of high-throughput 'Pt-Seq' to identify Pt-rRNA adducts following treatment of S. cerevisiae with cisplatin.
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