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Laboratory Procedures (laboratory + procedure)
Selected AbstractsA Laboratory Procedure for Optimal Implant Abutment PreparationJOURNAL OF PROSTHODONTICS, Issue 6 2009Tuncer Burak Özcelik DDS Abstract Simplicity and predictability have made cement-retained implant crowns the recent restoration of choice. The taper of the abutment is of particular importance for cement-retained implant restorations. The ideal taper of the implant abutment allows the clinician to control the overall retention of restorations. The technique described in this report presents the laboratory preparation of an implant abutment for a cement-retained crown using a counter gauge to control the preparation taper. [source] The effect of fixed-count subsampling on macroinvertebrate biomonitoring in small streamsFRESHWATER BIOLOGY, Issue 2 2000Craig P. Doberstein Summary 1When rigorous standards of collecting and analysing data are maintained, biological monitoring adds valuable information to water resource assessments. Decisions, from study design and field methods to laboratory procedures and data analysis, affect assessment quality. Subsampling - a laboratory procedure in which researchers count and identify a random subset of field samples - is widespread yet controversial. What are the consequences of subsampling? 2To explore this question, random subsamples were computer generated for subsample sizes ranging from 100 to 1000 individuals as compared with the results of counting whole samples. The study was done on benthic invertebrate samples collected from five Puget Sound lowland streams near Seattle, WA, USA. For each replicate subsample, values for 10 biological attributes (e.g. total number of taxa) and for the 10-metric benthic index of biological integrity (B-IBI) were computed. 3Variance of each metric and B-IBI for each subsample size was compared with variance associated with fully counted samples generated using the bootstrap algorithm. From the measures of variance, we computed the maximum number of distinguishable classes of stream condition as a function of sample size for each metric and for B-IBI. 4Subsampling significantly decreased the maximum number of distinguishable stream classes for B-IBI, from 8.2 for fully counted samples to 2.8 classes for 100-organism subsamples. For subsamples containing 100,300 individuals, discriminatory power was low enough to mislead water resource decision makers. [source] Development of a quick on-farm test to determine nitrate levels in soilJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2005Urs Schmidhalter Abstract Crop management can be optimized and nitrogen (N) losses can be reduced with a better knowledge of soil-nitrogen availability, especially if this information becomes directly available on-site in a fast and cost-effective way. In this paper, simple on-farm methods to determine nitrate-N in field-moist soil samples immediately after sampling are described. The procedures include volumetric soil sampling, extraction based on manual shaking with tap water as universally available extractant, filtering soil/extractant mixtures on-site, on-site determination of the soil water content, and reflectometric nitrate measurements based on test strips. Using correction factors can compensate the impact of the temperature during the final nitrate measurement. An excellent agreement was found between the developed quick-test procedures and the standard laboratory procedure. The proposed quick-test has great potential to enable economical savings for farmers as well as benefiting the environment. Entwicklung eines Schnelltestes zur Bestimmung des Nitratgehaltes in feldfeuchten Böden vor Ort Eine bessere Kenntnis der Stickstoff (N)-Verfügbarkeit des Bodens trägt zu Verbesserungen in der Bewirtschaftung und zu reduzierten Stickstoffverlusten bei, insbesondere wenn diese Information unmittelbar vor Ort rasch und billig zur Verfügung steht. Einfache Schnellmethoden zur direkten Bestimmung von Nitrat in feldfeuchten Bodenproben unmittelbar nach der Entnahme vor Ort werden beschrieben. Die vereinfachte Prozedur ermöglicht es, volumenbezogene Bodenproben zu entnehmen und die Lagerungsdichte des Bodens verlässlich zu bestimmen. Als universal erhältliches Extraktionsmittel kann Leitungswasser eingesetzt werden. Minimale Schüttelzeiten für die Extraktion wurden bestimmt. Die Nitrat-Messungen werden danach im klaren Überstand der Lösung oder nach einer stark vereinfachten Filterprozedur reflektometrisch mit nitratsensitiven Teststäbchen durchgeführt. Der Bodenwassergehalt kann unmittelbar vor Ort vereinfacht bestimmt werden. Die Temperaturabhängigkeit der Nitrat-Bestimmung kann durch die Nutzung von Korrekturfaktoren kompensiert werden. Die vorgeschlagenen Schnelltestmethoden zeigten eine sehr gute Übereinstimmung mit Standardbestimmungen im Labor. Die Methoden sind anwenderfreundlich und können zu ökonomischen Einsparungen bei den Landwirten führen sowie einen Beitrag zur Entlastung der Umwelt leisten. [source] Evaluation of interarch space for implant restorations in edentulous patients: A laboratory techniqueJOURNAL OF PROSTHODONTICS, Issue 2 2000Nicolas F. AbuJamra DDS This article describes a laboratory procedure for the visual evaluation of interarch space and its effect on implant prosthesis design. The method is applicable to patients presenting with completely edentulous arches. Silicone impression material is used to form a resilient cast and an external mold from an existing denture. The denture is duplicated using autopolymerizing acrylic resin. The duplicate denture and resilient cast are mounted on an articulator. Spatial relationships of anatomic landmarks can be evaluated, and a quantitative evaluation of available space can be made. The duplicate denture can also be used as a surgical template to direct implant placement. Reference tables are provided to serve as guidelines in the correlation between available space and minimum space required for various implant-assisted restorations. [source] The effect of fixed-count subsampling on macroinvertebrate biomonitoring in small streamsFRESHWATER BIOLOGY, Issue 2 2000Craig P. Doberstein Summary 1When rigorous standards of collecting and analysing data are maintained, biological monitoring adds valuable information to water resource assessments. Decisions, from study design and field methods to laboratory procedures and data analysis, affect assessment quality. Subsampling - a laboratory procedure in which researchers count and identify a random subset of field samples - is widespread yet controversial. What are the consequences of subsampling? 2To explore this question, random subsamples were computer generated for subsample sizes ranging from 100 to 1000 individuals as compared with the results of counting whole samples. The study was done on benthic invertebrate samples collected from five Puget Sound lowland streams near Seattle, WA, USA. For each replicate subsample, values for 10 biological attributes (e.g. total number of taxa) and for the 10-metric benthic index of biological integrity (B-IBI) were computed. 3Variance of each metric and B-IBI for each subsample size was compared with variance associated with fully counted samples generated using the bootstrap algorithm. From the measures of variance, we computed the maximum number of distinguishable classes of stream condition as a function of sample size for each metric and for B-IBI. 4Subsampling significantly decreased the maximum number of distinguishable stream classes for B-IBI, from 8.2 for fully counted samples to 2.8 classes for 100-organism subsamples. For subsamples containing 100,300 individuals, discriminatory power was low enough to mislead water resource decision makers. [source] Orthopaedic surgery in severe bleeding disorders: a low-volume, high-cost procedureHAEMOPHILIA, Issue 6 2002V. Mishra Summary. As more and more nations are scrutinizing their health care costs, attention has been focused on high-cost low-density disease. Assessment of actual total cost of care for haemophilia and its positive outcome becomes essential to justify support for these patients. In this study, we assessed hospital cost and diagnosis-related group (DRG) reimbursement for patients undergoing elective orthopaedic surgical procedures from May 1999 to December 1999. Hospital cost was assessed by a prospective microcost-analysis method. To identify real hospital costs, we performed registration of preoperative phase, operative phase and 1-year follow-up costs. Hospital cost included personnel costs and costs for clinical and laboratory procedures, blood products, prosthetic implants, coagulation factor concentrates and drugs. These data were compared with hospital DRG reimbursement. We included nine consecutive patients, with a mean age 38 years (19,54 years) who had had 10 major orthopaedic surgical procedures performed during the study period. Six patients had haemophilia A, two had haemophilia B and one had factor VII deficiency. Data analysis showed a mean cost of US$ 54 201 (range US$ 25 795,105 479; 1US$ = 8.5 NOK). The average actual hospital revenue (50% DRG reimbursement + income related to length of stay) was $4730 (range $ 1 308,13 601). Our study confirms that orthopaedic surgery in patients with severe bleeding disorders puts the hospital to a considerable expense. Activity-based financing, as used in Norway, does not provide a proper reimbursement for this part of the haemophilia care. [source] Does aversive behavior during toddlerhood matter?INFANT MENTAL HEALTH JOURNAL, Issue 4 2002The effects of difficult temperament on maternal perceptions, behavior Seventy-three mothers and their toddlers were observed when the children were 18 and 24 months of age in a series of laboratory procedures designed to assess relations among frustration distress, aggression/venting, and defiance, as indicators of aversive behavior, and their relations to maternal interactive style concurrently and over time. A second goal was to identify the predictors of aversive behavior at 24 months of age. Child aversive behavior as a predictor of increases in maternal negativity over time was also examined. Results indicated that distress, venting, and defiance were related to one another at 18 months of age. For boys, venting at 24 months of age, but not distress or defiance, was associated with greater maternal report of stress and higher incidence of behavior problems at 24 months of age. Venting behavior at 24 months of age was predicted by the interaction of early aversive behavior and low maternal positive guiding behavior. Increases in maternal negative behavior over the six-month period were predicted by the interaction of earlier negative maternal behavior and child sex, with negative mothers of boys displaying greater increases in negative behavior at the later age. These findings are discussed in terms of the significance of early aversive behavior, in the context of mother,child interaction, for later problematic behavior. ©2002 Michigan Association for Infant Mental Health. [source] Bonding strength between a hard chairside reline resin and a denture base material as influenced by surface treatmentJOURNAL OF ORAL REHABILITATION, Issue 12 2001C. R. Leles Direct relining of dentures made with hard chairside reline resins is faster than laboratory-processed reline systems and the patient is not without the prosthesis for the time necessary to perform the laboratory procedures. However, a weak bond between the autopolymerizing acrylic reline resins and the denture base material has been observed. This study evaluated the effect of six different surface treatments on the bond strength between a hard chairside reline acrylic resin and a heat-cured acrylic resin. Specimens of the heat-cured acrylic resin were divided into seven groups. One of these groups remained intact. In the other groups, a 10-mm square section was removed from the centre of each specimen. The bonding surfaces were then treated with (i) methyl methacrylate monomer, (ii) isobutyl methacrylate monomer, (iii) chloroform, (iv) acetone, (v) experimental adhesive and (vi) no surface treatment , control group. Kooliner acrylic resin was packed into the square sections and polymerized. The bonding strength was evaluated by a three-point loading test. The results were submitted to one-way analysis of variance (ANOVA) followed by a Tukey multiple range test at a 5% level of significance. No significant difference was found between the surface treatment with Lucitone 550 monomer or chloroform, but both were stronger than the majority of the other groups. The bond strength provided by all the surface treatments was lower than that of the intact heat-cured resin. [source] An Alternative Technique for Fabrication of an Occlusal DeviceJOURNAL OF PROSTHODONTICS, Issue 5 2008FACP, Mijin Choi DDS Abstract Several methods have been described for fabrication of occlusal devices, but many require complex and time-consuming laboratory procedures. In this article, an alternative fabrication method for a hard occlusal device while maintaining the articulation of the cast is described. [source] Influence of the storage time and the method of stimulation on whole blood chemiluminescenceLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2002Wojciech Podraza Abstract The ultra-weak light, chemiluminescence (CL), of stimulated leukocytes is a well-known phenomenon. Parameters of this CL are modified by many factors including laboratory procedures. The order of stimulation and enhancement (two possibilities) and two concentrations of luminol create four types of procedure, which were accomplished in five sample storage ,time points'. We received the strongest signals of CL using higher concentrations of luminol (and DMSO), but only when stimulation (FMLP) was used before enhancement (luminol); luminol used before FMLP strongly inhibited CL. For lower luminol concentration (and DMSO), the order of stimulation and enhancement was of no importance. There were comparable but weaker signals of CL in this case. We received stronger signals with storage time for all procedures. It may be dependent on the priming of phagocytes by releasing cell factors. Stimulation (FMLP) before enhancement (luminol) eliminates the inhibitory effect of DMSO on CL. Copyright © 2002 John Wiley & Sons, Ltd. [source] Defensibility and ethics in the laboratoryQUALITY ASSURANCE JOURNAL, Issue 2 2003Jo Ann Boyd Abstract Laboratory personnel must feel that ethical standards of conduct are a priority in the laboratory. Management must support this concept not only during training but also in daily communication to employees. Further, review of staff experience and training of employees is necessary to reinforce the need for ethics. This paper discusses defensibility and ethics in the laboratory, and the goals of assuring that the reporting of laboratory data will be performed in an ethical manner and will provide legal defensibility of data and laboratory procedures. Copyright © 2003 John Wiley & Sons, Ltd. [source] Two- and three-dimensional hydrated coordination polymers of diaqualanthanum(3+) ions with 2-hydroxypropanedioate, oxalate and acetate anions as bridging ligandsACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Rajesh Koner The title compounds, poly[[tetraaquadi-,-2-hydroxypropanedioato-,-oxalato-dilanthanum(III)] tetrahydrate], {[La2(C2O4)(C3H2O5)2(H2O)4]·4H2O}n, (I), and poly[[tetra-,-acetato-tetraaqua-,-oxalato-dilanthanum(III)] dihydrate], {[La2(C2O4)(C2H3O2)4(H2O)4]·2H2O}n, (II), represent crystalline hydrates of coordination polymers of diaqualanthanum(3+) ions with different combinations of bridging carboxylate ligands, viz. 2-hydroxypropanedioate and oxalate in a 2:2:1 ratio in (I), and acetate and oxalate in a 2:4:1 ratio in (II). While the acetate component was one of the reactants used, the other ligands were obtained in situ by aerial oxidation of the dihydroxyfumaric acid present in the reactions. The crystal structure of (I) consists of two-dimensional polymeric arrays with water molecules intercalated between and hydrogen bonded to the arrays. The oxalate components are located on inversion centres. The crystal structure of (II) reveals an open three-dimensional polymeric connectivity between the interacting components, with the solvent water molecules incorporated within the intralattice voids and hydrogen bonded to the polymeric framework. The LaIII ion and the noncoordinated water molecules are located on axes of twofold symmetry. The oxalate group is centred at the 222 symmetry site, the intersection of the three rotation axes. The coordination number of the LaIII ion in the two structures is 10. The significance of this study lies mainly in the characterization of two new coordination polymers, as well as in the confirmation that dihydroxyfumaric acid tends to rearrange to form smaller components in standard laboratory procedures, and should be considered a poor reagent for formulating hybrid coordination polymers with metal ions. [source] Requirements for the welfare of baboons and pigs used in animal-to-animal xenotransplantation experimentsAUSTRALIAN VETERINARY JOURNAL, Issue 10 2009N Cross Objective Review the welfare requirements of pigs and baboons used for xenotransplantation in research laboratories. Because of the requirements to maintain optimum health status, these animals are often kept in barren enclosures with little or no enrichment. They may also be exposed to procedures causing stress and discomfort. Although animal-to-human xenotransplantation is, at the present time, not approved in Australia, research is currently being performed to develop laboratory procedures, using the pig-to-baboon model. Results and conclusion We make recommendations for the husbandry of baboons and pigs used for xenotransplantation, to increase their welfare and minimise stress during experimental procedures, while attempting to preserve the health status required. It is proposed that novel standards should be devised and implemented for baboons, whereas existing pig welfare appraisal schemes could, with minor changes, be suitable for assessing the welfare of pigs used for xenotransplantation. [source] | |||||||||||||