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At least 19 recordsLinked to original sources
PubMed1990

Effects of the diamond grit sizes of the commercial dental diamond points on the weight-load cutting of bovine enamel and glass-ceramic Typodont teeth.

To evaluate the effect of the diamond grit size of commercial dental diamond points on the dental cutting, we conducted weight-load cutting tests on bovine enamel and glass-ceramic typodont teeth using 3 different diamond grit sizes and air-bearing and ball-bearing air-turbine driven handpieces. With the transverse load applied on the diamond point varied between 20 and 80 g, we measured rotational cutting speed and cutting volume. Generally, increases in applied load caused decreases in rotational cutting speed and increases in cutting volume. The intensity of this trend, however, differed between grit sizes. Regular grit diamond points most strongly showed this tendency, while super-fine grit diamond points were least affected. Fine grit diamond points behaved in a manner similar to regular grit points.

Animals↗
PubMed1975

Regulation and grinding ability of grit in the gizzard of Norwegian willow ptarmigan (Lagopus lagopus).

Fluctuations in grit composition in the gizzards of willow ptarmigans and the grinding ability of various grit assortments from wild ptarmigans were examined. We confirmed reports of other investigators that larger, fewer and rounder stones were present in the winter than in the autumn. Experiments showed that ptarmigans prefer stones with diameters between 2-5 mm. Birds on a constant diet maintained a constant stone intake throughout the year. The composition of gizzard grit was influenced by the availability of stones as well as of the type of food the ptarmigans ate. Using an artificial gizzard, grit from birds shot during the autumn was found to be a more efficient grinding material than grit from winter birds. We suggest that other functions than grinding, such as supplying minerals, may be equally important functions of the grit.

Animals↗
PubMed1991

[The effect of diamond grinding instrument of different grit on dental hard tissue].

Under practice-related conditions 100 human molars and premolars were prepared with diamond grinding instruments of different grit. We obtained the smoothest surfaces by using the extra-fine grit at 250,000 rpm, thus indicating the suitability of these instruments for finishing cavity walls especially at high rotating speeds. Only slight differences were found between medium and coarse grit. The time saved by choosing the super-coarse grit for preparation is largely compensated because finishing of rough cavity walls will take longer. No constant effect of the rotating speeds on the depth of roughness of cavity walls was observed.

Carbon↗
PubMed2026

Playing with Fire, Losing the Drive: Bidirectional Links Between Problematic Smartphone Use and Grit Dimensions.

This study examined bidirectional longitudinal associations between grit dimensions (consistency of interest [CI] and perseverance of effort [PE]) and problematic smartphone use (PSU) and tested cognitive flexibility as a mediating mechanism. A sample of 1,641 Chinese university students (55.2 percent female; Mage = 20.1 years) completed measures at two time points 6 months apart. A four-variable cross-lagged panel model revealed that CI and PSU negatively predicted each other over time, whereas PSU unidirectionally predicted decreased PE. Cognitive flexibility partially mediated the PSU-to-PE pathway (indirect effect = -0.004, 95 percent bootstrap CI [-0.010, -0.0001]). Competing models analysis confirmed this directionality: the forward mediation (PSU → cognitive flexibility → PE) was significant, whereas the reverse was not. These findings demonstrate that grit dimensions exhibit distinct longitudinal patterns with PSU and identify cognitive flexibility as a cognitive mechanism through which PSU specifically undermines effort persistence. Implications for dimensional approaches to grit and targeted interventions are discussed.

Humans↗
PubMed1992

Torsional stability of HA-coated and grit-blasted titanium dental implants.

Hydroxylapatite (HA)-coated and grit-blasted (non-HA-coated) titanium dental implants were inserted into healed extraction sites of canine mandibles. After six weeks, the animals were killed and the implants mechanically tested in torsion to failure. Interface attachment strength, implant/tissue compatibility, integrity of the HA coating, and the location of interface failure were evaluated. Mechanical testing demonstrated an interface torsional strength of 3.98 +/- 0.93 MPa for the HA-coated implants and 2.25 +/- 0.65 MPa for the grit-blasted implants. This represents a 76.9% improvement in the maximum torsional interface strength, and is statistically-significant (p = 0.0004). On qualitative histologic analysis, interface failure was seen to occur primarily at the HA/implant interface, although failure through the HA coating and regions of bone/HA interface failure were observed. The HA-coated implants had bone in direct apposition to their surface with no fibrous tissue interposition. The grit-blasted implants also had regions of direct bone-implant apposition, but these areas were limited to a smaller proportion of the total interface area. There was no evidence of breakdown or change in thickness of the HA coating.

Animals↗
PubMed1991

Red imported fire ant (Hymenoptera: Formicidae) control with a corn grit bait of fenoxycarb without soybean oil.

The standard fenoxycarb fire ant bait formulation (Logic), composed of pregel defatted corn grits and soybean oil toxicant, was modified by eliminating the soybean oil. This formulation without soybean oil contained greater than 2 times more fenoxycarb and was as effective as the standard bait formulation against laboratory colonies of red imported fire ant, Solenopsis invicta Buren. In field tests, the modified and standard baits were equally effective in controlling fire ants after 6, 12, and 18 wk. Individual worker ants obtained from plots treated with fenoxycarb baits without soybean oil had greater than 47 times less fenoxycarb than did workers from the plots treated with the standard fenoxycarb baits containing soybean oil.

Animals↗
PubMed1990

Effect of dentin surface roughness on shear bond strength.

The aim of this investigation was to evaluate the effect of dentin surface roughness on the shear bond strength of a dentin bonding agent. Seventy-five dentin samples were divided into five surface preparation groups: (1) 60-grit SiC; (2) 320-grit SiC; (3) 600-grit SiC; (4) 600-grit SiC followed by AI2O3, and (5) 320-grit SiC followed by a #245 carbide bur. The prepared dentin was treated with a dentin primer, and one coat of dentin bonding agent was applied and light-cured for 30 s. Each dentin specimen was mounted in a device with a split Teflon mold (I.D. = 3.5 mm, depth = 5.0 mm). Three increments of a restorative composite were placed, compressed firmly, and light-cured for 30 s in the mold. After 24 h of storage, the bonds were stressed to failure in a mechanical testing machine at a cross-head speed of 0.5 mm/min. Weibull analysis was used to obtain a shape factor and characteristic level for each group. The results showed that, with the possible exception of the 600-grit SiC and AI2O3 group, the grit size used for preparation of dentin specimens for shear bond strength testing in this study did not significantly affect bond strength.

Dental Bonding↗
PubMed1992

Efficacy of a porcelain refinishing system in restoring surface finish after grinding with fine and extra-fine diamond burs.

Commercial porcelain refinishing kits are claimed to restore the surface finish on porcelain after adjustments in circumstances that preclude reglazing. This study investigates the efficacy of one such kit in restoring a Vitadur N porcelain surface finish after grinding with fine (30 microns grit-red band) and extra-fine (15 microns grit-yellow band) high-speed diamond burs. The production of the porcelain test samples, the refinishing procedures, and the refinishing times were standardized throughout. Techniques were selected to simulate clinical practice. Randomly selected examples of surfaces created during refinishing were subjected to scanning electron microscopy, using standard kV and tilt angle settings, and to surface profilometry tracings. Roughness average (Ra) readings were recorded for each test specimen for every surface finish. Ra readings were analyzed statistically using a two-way unbalanced model for analysis of variance. Although refinishing after grinding with a 15 microns grit bur produced surfaces significantly smoother than on specimens previously ground with the 30 microns grit burs, the surfaces remained significantly rougher than when originally glazed. It is concluded that, using the type of kit tested, burs of a grade finer than the existing 15 microns grit yellow band types would be appropriate for porcelain adjustments to permit subsequent refinishing to a surface smoothness comparable to the original glaze.

Aluminum Oxide↗
PubMed1992

Gel extenders in larval diet of Cochliomyia hominivorax (Diptera: Calliphoridae).

Larvae of the screwworm, Cochliomyia hominivorax (Coquerel), were reared on meridic diets containing ground corncob material (grit) in test 1 and the cob grit or sawdust in test 2 to reduce or replace the amount of an expensive synthetic copolymer gelling agent. Biological parameters for the tests included pupal yield (total number), pupal weight (size), pupal malformation, adult emergence, adult malformation, egg weight, and egg hatch to assess for any significant differences. In the first test, larval propagation was successful for five consecutive generations on 24 of an original 37 formulations. Results indicate that a minimum concentration of 4% of the cob grit is needed to reduce the gel by 50%; at least 8% concentration is needed to reduce the gel by 80%; and at least 12% concentration is needed to replace the gel completely. In the second test, the larvae were successfully propagated for five consecutive generations when the copolymer gel was reduced by 50 or 75% in the diet by using either sawdust or the no. 60 cob grit size. The cost savings and applications of use of sawdust or the cob grit incorporated into the larval diet can be beneficial to a mass-production screwworm program.

Acrylic Resins↗
PubMed1990

Adherence of HDPE powder coating on Co-Cr surfaces: effect of substrate preparation and gas sterilization.

As part of the development of a hemiarthroplasty implant with a compliant surface layer, the effect of surface preparation of a cast Co-Cr alloy substrate on the adhesion of a polymeric coating was studied. High-density polyethylene (HDPE) coatings were deposited on Co-Cr alloys without adhesive by spraying powder onto the surface of specimens maintained at a controlled temperature. Prior to deposition, two different types of surface preparation were carried out: chemical etching and grit-blasting. Adherence tests were performed in order to study the effect of the surface preparation of a Co-Cr alloy on the adherence of the HDPE film. The etching process enhanced the adherence by a factor of 10 compared to the grit-blasting process. For coatings deposited on grit-blasted Co-Cr surfaces, rupture occurred at the interface (adhesive mode) as well as in the coating (cohesive mode). A full cohesive mode was observed for films deposited on etched surfaces. Gas sterilization with an ethylene oxide and Freon 12 solution did not change significantly the adherence of the film deposited on etched surfaces. Examination of the surfaces indicated that the etching process created a specific type of porosity consisting of dendritic cavities whereas grit-blasting produced surface irregularities. Cavities produced by etching were larger that the polymer powder particles and could be easily filled. The coating of an etched Co-Cr alloy substrate with a layer of HDPE provided an interface that could probably sustain the physiological loading in a normal synovial joint.

Biocompatible Materials↗
PubMedDate not supplied

[Change in the sugar content in oaten products, buckwheat and rice groats during their heat processing by cooking].

The sugar content in the grits and in a gruel cooked with samples of oats and buckwheat subjected to hydrothermal treatment under different conditions and also in the oat flour, a product of baby and dietetic nutrition, was quantified. Hydrothermal processing results in significant changes occurring individual sugars of the grit. During culinary treatment these changes are levelled out, but in the end the level of virtually all types of sugar is higher in the gruel cooked with hydrothermally treated grit than in that prepared with initial, untreated grit. The oats flour is distinguished by a high glucose, maltose, fructose and saccharose content. A fall of the reducing sugars level coming as a result of thermal and culinary treatment is explained by their participating in the reaction of melanoidine formation. On the other hand, a rise in their content under rigorous conditions and in the production of oat flour is due to the starting of the starch hydrolysis.

Carbohydrates↗
PubMed1992

[Method of producing fusarin C in perlite-liquid culture medium].

For researching the biosynthesis labelled Fusarin C(Fc) by Fuscarium moniliforme, a more quick and convenient method of Fusarin C production and purification were established, and a good liquid culture medium consisted of different kinds organic matters (hydroxy proline, sucrose and glycerin), inorganic salts and perlite replaced corn grit medium. The perlite-liquid culture medium inoculated with the strain of F. moniliforme yields 936mg Fc/kg organic matter with in 14 days of incubation at 28 degrees C. As compared with the corn grit medium, the amount of Fc from perlite-liquid medium was more than that from corn grit medium (831mg Fc/kg corn grit). In all experiments both thin-layer chromatography and high-pressure liquid chromatography were used to confirm the presence of Fc. parameters which were important for the optimal biosynthesis of Fc included hydroxy proline and sucrose concentrations, incubated time/temperature and amount of perlite. The 40g of sucrose/L liquid culture was optimal concentration for Fusarin C production. Of three contained N-matter tested, hydroxy proline was the best sources of N-atom for Fusarin C. Under the absence of hydroxy proline, the Fc wasn't synthesized in perlite-liquid culture medium by F. moniliforme. A culture time/temperature study of Fc production was done, and the optimal Fc amounts was synthesized after incubation for 14 days at 28 degrees C on perlite-liquid culture medium.

Aluminum Oxide↗
PubMed1991

Influence of surface characteristics on bone integration of titanium implants. A histomorphometric study in miniature pigs.

The purpose of the present study was to evaluate the influence of different surface characteristics on bone integration of titanium implants. Hollow-cylinder implants with six different surfaces were placed in the metaphyses of the tibia and femur in six miniature pigs. After 3 and 6 weeks, the implants with surrounding bone were removed and analyzed in undecalcified transverse sections. The histologic examination revealed direct bone-implant contact for all implants. However, the morphometric analyses demonstrated significant differences in the percentage of bone-implant contact, when measured in cancellous bone. Electropolished as well as the sandblasted and acid pickled (medium grit; HF/HNO3) implant surfaces had the lowest percentage of bone contact with mean values ranging between 20 and 25%. Sandblasted implants with a large grit and titanium plasma-sprayed implants demonstrated 30-40% mean bone contact. The highest extent of bone-implant interface was observed in sandblasted and acid attacked surfaces (large grit; HCl/H2SO4) with mean values of 50-60%, and hydroxylapatite (HA)-coated implants with 60-70%. However, the HA coating consistently revealed signs of resorption. It can be concluded that the extent of bone-implant interface is positively correlated with an increasing roughness of the implant surface.

Animals↗
PubMed1991

Histological and clinical comparisons of guided tissue regeneration on dehisced hydroxylapatite-coated and titanium endosseous implant surfaces: a pilot study.

Fifty-six endosseous cylindrical implants were placed in dog mandibles 12 weeks after the extraction of all mandibular premolars and first molars. Eight implants, four coated with 50 microns of hydroxylapatite (HA) and four grit-blasted and titanium-surfaced, were placed in each dog. Ideal implant placement sites were modified by creating standardized 3 x 5-mm facial dehiscence defects. Half the dehiscences were treated with a modified expanded polytetrafluoroethylene (PTFE) membrane; the remainder served as controls. After 8 weeks of healing, the animals were sacrificed and measurements made to determine the percentage of dehiscence repair. The HA-coated implants had a mean defect fill of 95.17% and the grit-blasted implants had a percent fill of 82.8% in the guided tissue regeneration (GTR) test group; the control implants demonstrated a mean fill of 55% and 39% in the HA-coated and grit-blasted implants, respectively. Significant differences (P less than .05) were noted between both test groups and the titanium control group, and between the HA test and HA control groups. Histologic evaluation showed significantly greater repair associated with HA-coated implants, as well as significant bone loss associated with clinically exposed membranes. It was concluded that within the limitations of this study, guided tissue regeneration is a viable option in treating defects associated with dental implants.

Alveolar Bone Loss↗
PubMedDate not supplied

[Amino acid composition and biologic value of the proteins of several sorts of buckwheat].

The amino acids composition of summary proteins in unground buckwheat of four common and promising varieties grown in the Ukraine was investigated by using ion-exchange chromatography with an automatic analyzor Hd-1200 E. Between individual varieties of buckweheat no essential differences in the amino acids content were in evidence. The total proteins of the buckwheat grit contain high quantities of lysine, treonine, leucine, glutamic acid and arginine. The amino acids score was instrumental in determining the biological value and in eliciting amino acids limiting this value in different grits. These data may be made use of in the practice of public catering for estimating formulae of meals prepared with grits differently combined with other products securing an improved amino acids composition of ready-to-eat meals.

Amino Acids↗
PubMed1978

Soy protein utilization in food systems.

Soy protein products are utilized in food systems as whole beans, flours and grits, concentrates and isolates, and textured products. Soy proteins play a significant role in food systems as a source of supplementary and complementary protein and contribute functional properties such as solubility, water absorption, viscosity, emulsification, texture, and antioxidation. Whole soybeans are processed into snack foods, beverages, and fermented foods. Soy protein is an ideal supplement for cereal protein because it corrects lysine and other amino acid deficiencies. Blends of soy flour or grits with cereals such as corn, wheat, or sorghum are widely used in world feeding programs. The blends are also valuable in domestic food systems such as breakfast cereals and baked foods. Concentrates and isolates are utilized in processed meats and baby foods. Isolates are utilized in processed meats and baby foods. Isolates are employed as whipping agents and coffee whiteners. Thermoplastic extrusion of defatted flours or protein concentrates produces an expanded type of textured protein. Isolated soy protein is converted to meat analogs by a spun fiber process. Textured soy protein products are used to extend or replace meat products in food systems.

Amino Acids, Essential↗