The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Dale P Bentz - One of the best experts on this subject based on the ideXlab platform.
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activation energies of high volume fly ash ternary blends hydration and setting
Cement & Concrete Composites, 2014Co-Authors: Dale P BentzAbstract:Because ready-mixed concrete is placed under a wide variety of environmental conditions, the influence of temperature on the hydration reactions and the accompanying setting process is of critical importance. While contractors are generally quite comfortable with the temperature sensitivity of conventional ordinary portland cement (OPC) concretes, more sustainable mixtures containing high volumes of fly ash (HVFA), for example, often present problems with delayed setting times and increased temperature sensitivity. Based on isothermal calorimetry and Vicat Needle Penetration measurements, this study demonstrates that the high temperature sensitivity of such HVFA mixtures can be effectively moderated by the replacement of a portion of the fly ash with a fine calcium carbonate powder. In addition to accelerating and amplifying hydration and reducing setting times at a given temperature, the presence of the fine CaCO3 powder also lowers the apparent activation energy for setting for temperatures below 25 °C. The reactivity of the CaCO3 in these mixtures is quantified using thermogravimetric analysis. Comparison of results for CaCO3 powders of nominal sizes of 1 µm and 17 µm, replacing 10 % by volume of the cement in an OPC mixture, indicates that the former is highly superior in accelerating/amplifying hydration and reducing setting times.
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rheology and setting of high volume fly ash mixtures
Cement & Concrete Composites, 2010Co-Authors: Dale P Bentz, Chiara F FerrarisAbstract:While high volume fly ash (HVFA) concretes can be designed and produced to meet 28-d strength requirements and often even exceed the durability performance of conventional concretes, a persistent problem is the potentially long delay in setting time that produces concurrently long delays in finishing the concrete in the field. Previous isothermal calorimetry studies on two different powder additions, namely calcium hydroxide and a rapid set cement, have shown that these powders can mitigate excessive retardation of the hydration reactions. In this paper, rheological measurements and conventional Vicat setting time studies are conducted to verify that these powder additions do indeed reduce setting times in paste systems based on both ASTM Class C and ASTM Class F fly ashes. The reductions depend on the class of fly ash and suggest that trial mixtures would be a necessity to apply these technologies to each specific fly ash/cement/admixture combination being employed in the field. Potentially, for such screening studies, the rheological measurement of yield stress may provide a faster indication of setting (and finishability) than conventional Vicat Needle Penetration measurements on pastes.
Seyhmus Yigit - One of the best experts on this subject based on the ideXlab platform.
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effects of topical alkane vapocoolant spray on pain intensity prior to digital nerve block for ingrown nail surgery
Foot and Ankle Specialist, 2010Co-Authors: Ozkan Kose, Sedat Saylan, Naim Ediz, Seyhmus YigitAbstract:Needle Penetration and local anesthetic infiltration are 2 painful steps that cause considerable stress and anxiety during digital nerve block, which is the most frequently used regional anesthesia for ingrown nail surgery. The purpose of this study was to evaluate the effectiveness of topical alkane vapocoolant spray in decreasing pain during digital nerve block for ingrown nail surgery. The authors conducted a prospective, randomized clinical trial with 62 patients who underwent big toenail surgery. Prior to the digital block, alkane vapocoolant spray was applied to patients who were selected by flipping a coin. A visual analog scale (VAS) was used for assessment of pain during the skin Needle Penetration and during the infiltration of the anesthetic product. VAS scores during Needle Penetration were significantly lower in the intervention group. However, VAS scores during infiltration were similar statistically. Alkane vapocoolant spray has no noticeable clinical benefit in decreasing pain intensity during digital nerve block in patients undergoing toenail surgery.
Chiara F Ferraris - One of the best experts on this subject based on the ideXlab platform.
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rheology and setting of high volume fly ash mixtures
Cement & Concrete Composites, 2010Co-Authors: Dale P Bentz, Chiara F FerrarisAbstract:While high volume fly ash (HVFA) concretes can be designed and produced to meet 28-d strength requirements and often even exceed the durability performance of conventional concretes, a persistent problem is the potentially long delay in setting time that produces concurrently long delays in finishing the concrete in the field. Previous isothermal calorimetry studies on two different powder additions, namely calcium hydroxide and a rapid set cement, have shown that these powders can mitigate excessive retardation of the hydration reactions. In this paper, rheological measurements and conventional Vicat setting time studies are conducted to verify that these powder additions do indeed reduce setting times in paste systems based on both ASTM Class C and ASTM Class F fly ashes. The reductions depend on the class of fly ash and suggest that trial mixtures would be a necessity to apply these technologies to each specific fly ash/cement/admixture combination being employed in the field. Potentially, for such screening studies, the rheological measurement of yield stress may provide a faster indication of setting (and finishability) than conventional Vicat Needle Penetration measurements on pastes.
Harry W. Flynn - One of the best experts on this subject based on the ideXlab platform.
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management of inadvertent Needle Penetration resulting in subretinal triamcinolone acetonide and retinal detachment
American Journal of Ophthalmology Case Reports, 2018Co-Authors: Kimberly D. Tran, Ashley M. Crane, Harry W. FlynnAbstract:Abstract Purpose To report management of inadvertent Needle Penetration during subtenons triamcinolone acetonide administration resulting in retinal detachment. Observations A 71-year-old female with history of diabetes, hypothyroidism, and mild myopia underwent subtenons triamcinolone acetonide (TA) injection in the right eye for nodular scleritis. There was unexpected patient movement concurrent with the injection resulting in Needle Penetration, subretinal and intravitreal injection of TA, superotemporal retinal break, and macula-involving retinal detachment. The patient underwent partial subretinal TA removal, successful retinal detachment repair, and recovered 20/25 visual acuity. Conclusions and importance In spite of prominent subretinal TA and retinal detachment, successful repair of retinal detachment and recovery of good visual acuity is possible.
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Management of inadvertent Needle Penetration resulting in subretinal triamcinolone acetonide and retinal detachment
Elsevier, 2018Co-Authors: Kimberly D. Tran, Ashley M. Crane, Harry W. FlynnAbstract:Purpose: To report management of inadvertent Needle Penetration during subtenons triamcinolone acetonide administration resulting in retinal detachment. Observations: A 71-year-old female with history of diabetes, hypothyroidism, and mild myopia underwent subtenons triamcinolone acetonide (TA) injection in the right eye for nodular scleritis. There was unexpected patient movement concurrent with the injection resulting in Needle Penetration, subretinal and intravitreal injection of TA, superotemporal retinal break, and macula-involving retinal detachment. The patient underwent partial subretinal TA removal, successful retinal detachment repair, and recovered 20/25 visual acuity. Conclusions and importance: In spite of prominent subretinal TA and retinal detachment, successful repair of retinal detachment and recovery of good visual acuity is possible. Keywords: Needle Penetration, Retrobulbar injection, Peribulbar injectio
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Needle Penetration of the globe during retrobulbar and peribulbar injections
Ophthalmology, 1991Co-Authors: Andy Hay, Harry W. Flynn, Joseph I Hoffman, Alfred H RiveraAbstract:The charts of 23 patients with Needle Penetration of the globe during retrobulbar or peribulbar injections between January 1980 and May 1990 were reviewed. Possible Needle Penetration risk factors included high myopia, previous scleral buckling procedures, injection by nonophthalmologists, and poor patient cooperation during the injection. Of the 23 cases of ocular Penetration, 16 (70%) were from sharp (22-, 23-, and 25-gauge) Needles, and 7 (30%) were from blunt (23- and 25-gauge) Needles. Management options depended on the severity of the intraocular injury. Retinal breaks without retinal detachment were treated by laser photocoagulation (four cases) or cryopexy (one case) and were observed in three cases. More advanced complications (retinal detachment and vitreous hemorrhage) were usually treated by pars plana vitrectomy with or without a scleral buckle (12 of 14 cases). The final visual acuity was 20/400 or better in only 2 of the 14 retinal detachment cases. In cases without retinal detachment, the final visual acuity was 20/50 or better in 7 of 9 cases.
David A Vorp - One of the best experts on this subject based on the ideXlab platform.
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mechanics of anesthetic Needle Penetration into human sciatic nerve
Journal of Biomechanics, 2018Co-Authors: Joseph E Pichamuthu, Spandan Maiti, Maria G Gan, Nicole M Verdecchia, Steven L Orebaugh, David A VorpAbstract:Abstract Nerve blocks are frequently performed by anesthesiologists to control pain. For sciatic nerve blocks, the optimal placement of the Needle tip between its paraneural sheath and epineurial covering is challenging, even under ultrasound guidance, and frequently results in nerve puncture. We performed Needle Penetration tests on cadaveric isolated paraneural sheath (IPS), isolated nerve (IN), and the nerve with overlying paraneural sheath (NPS), and quantified puncture force requirement and fracture toughness of these specimens to assess their role in determining the clinical risk of nerve puncture. We found that puncture force (123 ± 17 mN) and fracture toughness (45.48 ± 9.72 J m−2) of IPS was significantly lower than those for NPS (1440 ± 161 mN and 1317.46 ± 212.45 Jm−2, respectively), suggesting that it is not possible to push the tip of the block Needle through the paraneural sheath only, without pushing it into the nerve directly, when the sheath is lying directly over the nerve. Results of this study provide a physical basis for tangential placement of the Needle as the ideal situation for local anesthetic deposition, as it allows for the Penetration of the sheath along the edge of the nerve without entering the epineurium.
