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Instrument Design (instrument + design)
Selected AbstractsCyclic fatigue resistance and three-dimensional analysis of instruments from two nickel,titanium rotary systemsINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2006N. M. Grande Abstract Aim, To determine how instrument design affects the fatigue life of two nickel,titanium (Ni,Ti) rotary systems (Mtwo and ProTaper) under cyclic fatigue stress in simulated root canals. Methodology, Cyclic fatigue testing of instruments was performed in stainless steel artificial canals with radii of curvature of 2 or 5 mm and an angle of curvature of 60°. A total of 260 instruments were rotated until fracture occurred and the number of cycles to failure were recorded. The morphology of Ni,Ti rotary instruments was investigated by measuring the volume of millimetre slices of each instrument size starting from the tip to the shank by means of ,CT analysis. The fracture surface of three representative samples of each size was analysed by scanning electron microscopy (SEM). Data were analysed by one-way anova, Holm t -test, paired t -test and linear regression; the significance was determined at the 95% confidence level. Results, Cycles to failure significantly decreased as the instrument volume increased for both the radii of curvature tested (P < 0.01). The radius of curvature had a statistically significant influence on the fatigue life of the instruments (P < 0.05). Larger instruments underwent fracture in less time under cyclic stress than smaller ones. SEM evaluation showed typical features of fracture through fatigue failure. Conclusions, The metal volume in the point of maximum stress during a cyclic fatigue test could affect the fatigue life of Ni,Ti rotary instruments. The larger the metal volume, the lower the fatigue resistance. [source] Cross-sectional studies in prescribing researchJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 6 2001J. Jesson BSc PhD A cross-sectional study aims to describe the overall picture of a phenomenon, a situational problem, an attitude or an issue, by asking a cross-section of a given population at one specified moment in time. This paper describes the key features of the cross-sectional survey method. It begins by highlighting the main principles of the method, then discusses stages in the research process, drawing on two surveys of primary care pharmacists to illustrate some salient points about planning, sampling frames, definition and conceptual issues, research instrument design and response rates. Four constraints in prescribing studies were noted. First the newness of the subject meant a low basis of existing knowledge to design a questionnaire. Second, there was no public existing database for the sampling frame, so a pragmatic sampling exercise was used. Third, the definition of a Primary Care Pharmacist (PCP) [in full] and respondents recognition of that name and identification with the new role limited the response. Fourth, a growing problem for all surveys, but particularly with pharmacists and general practitioners (GP) [in full] is the growing danger of survey fatigue, which has a negative impact on response levels. [source] NONCONTACT TEMPERATURE MONITORING OF A PELLETING PROCESS USING INFRARED THERMOGRAPHYJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2007C. SALAS-BRINGAS ABSTRACT Contact methods are commonly used to determine temperature during food and feed manufacturing processes. This may, however, result in incorrect temperature measurements, because many food and feed materials easily agglomerate around the thermowell tip of the sensors, decreasing their time response; also, it is difficult to measure temperature from moving objects using contact methods. This article assesses the use of thermography to measure temperature throughout the manufacture of poultry feed. The experiment showed that precaution should be used when the temperature difference, between the meal at the outlet of the conditioner and pellets at the outlet of the pellet press, is associated with the temperature rise across the die. Precaution should also be used when the temperature of the pellets at the outlet of the pellet press is used as the peak temperature during the process. Temperature measurements through infrared emissions require improved instrument design to operate in a dusty, damp, steamy and oily environment. [source] Attitudes Toward Nurse Practitioners: Influence of Gender, Age, Ethnicity, Education and IncomeJOURNAL OF THE AMERICAN ACADEMY OF NURSE PRACTITIONERS, Issue 7 2000Carol Y. Phillips PhD ABSTRACT Survey research was undertaken to measure relationships between gender, age, ethnicity, education, income level, and an individual's attitude toward using a nurse practitioner (NP) for health care. Pender's Health Promotion Model provided the theoretical basis for the research initiative and instrument design. Following initial pilot work, 238 individuals were surveyed. While no significant differences on the basis of gender and race were found, high school graduates demonstrated significantly more positive attitudes toward NPs than non-high school graduates, and older subjects and those with lower incomes were less positively inclined to use NP services. These findings have implications for the marketing of NP services, NP education, and public education, and should be used as a basis for additional research in this area. [source] Femtosecond electron diffraction: Direct probe of ultrafast structural dynamics in metal filmsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2009Shouhua Nie Abstract Femtosecond electron diffraction is a rapidly advancing technique that holds a great promise for studying ultrafast structural dynamics in phase transitions, chemical reactions, and function of biological molecules at the atomic time and length scales. In this paper, we summarize our development of a tabletop femtosecond electron diffractometer. Using a delicate instrument design and careful experimental configurations, we demonstrate the unprecedented capability of detecting submilli-ångström lattice spacing change on a subpicosecond timescale with this new technique. We have conducted an in-depth investigation of ultrafast coherent phonon dynamics induced by an impulsive optical excitation in thin-film metals. By probing both coherent acoustic and random thermal lattice motions simultaneously in real time, we have provided the first and unambiguous experimental evidence that the pressure of hot electrons contributes significantly to the generation of coherent acoustic phonons under nonequilibrium conditions when electrons and phonons are not thermalized. Based on these observations, we also propose an innovative approach to measure the electronic Grüneisen parameter in magnetic materials at and above room temperature, which provides a way to gain new insights into electronic thermal expansion in ferromagnetic transition metals. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc. [source] A new hybrid electrospray Fourier transform mass spectrometer: design and performance characteristicsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 2 2006Peter B. O'Connor A new hybrid electrospray quadrupole Fourier transform mass spectrometry (FTMS) instrument design is shown and characterized. This instrument involves coupling an electrospray source and mass-resolving quadrupole, ion accumulation, and collision cell linear ion trap system developed by MDS Sciex with a home-built ion guide and ion cyclotron resonance (ICR) cell. The iterative progression of this design is shown. The final design involves a set of hexapole ion guides to transfer the ions from the accumulation/collision trap through the magnetic field gradient and into the cell. These hexapole ion guides are separated by a thin gate valve and two conduction limits to maintain the required <10,9,mbar vacuum for FTICR. Low-attomole detection limits for a pure peptide are shown, 220,000 resolving power in broadband mode and 820,000 resolving power in narrow-band mode are demonstrated, and mass accuracy in the <2,ppm range is routinely available provided the signal is abundant, cleanly resolved, and internally calibrated. This instrument design provides high experimental flexibility, allowing Q2 CAD, SORI-CAD, IRMPD, and ECD experiments with selected ion accumulation as well as experiments such as nozzle skimmer dissociation. Initial top-down mass spectrometry experiments on a protein is shown using ECD. Copyright © 2005 John Wiley & Sons, Ltd. [source] Bridging the educational research-teaching practice gapBIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 1 2010Tools for evaluating the quality of assessment instruments Abstract Student assessment is central to the educational process and can be used for multiple purposes including, to promote student learning, to grade student performance and to evaluate the educational quality of qualifications. It is, therefore, of utmost importance that assessment instruments are of a high quality. In this article, we present various tools that instructors could use, both to improve instrument design and validity before presentation to students and, to evaluate the reliability and quality of the assessment after students have answered the questions. In keeping with our goals of the Bridging-the-Gap series, we also present various ideas from the educational literature regarding the evaluation of assessment quality and end with a list of criteria that instructors could use to guide their evaluation process. [source] Nonlinear modeling of protein separation in a preparative-scale dynamic field gradient focusing instrumentAICHE JOURNAL, Issue 1 2009Noah I. Tracy Abstract Dynamic field gradient focusing (DFGF) uses an electric field gradient opposed by a counter-flow of buffer to separate milligrams of proteins according to their electrophoretic mobilities. A nonlinear model of protein separation in a preparative-scale DFGF device was developed to aid in refining the instrument's design and finding optimal run conditions prior to performing experiments. The model predicted the focal points of bovine serum albumin (BSA), and bovine hemoglobin (Hb) to within the 95% confidence intervals about the means of the experimental values. The resolution between the proteins in the model was 2.08, which was 3% less than the lower limit of the 95% confidence interval about the experimental value. The model predicted 67% more dispersion than was present in the experimental device, which made the simulated BSA peak 22% wider than the experimentally measured width. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source] | |||||||||||||