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101.
The effect of pitching rate on fermentation and production of flavour compounds was studied in high gravity wort using a lager yeast. Fermentation performance was followed by monitoring the total sugar content and yeast growth. Volatile compounds were evaluated by analysing higher alcohols, esters and carbonyl compounds at the end of fermentation. Faster fermentation rates and higher yeast counts were observed with the higher pitching levels. Lower amounts of 2‐ and 3‐methyl‐1‐butanols and higher levels of 2‐methyl‐1‐propanol were found at the increased pitching rates. The concentration of isoamyl acetate was reduced with an increased pitching rate. Higher amounts of diacetyl and 2,3‐pentanedione were obtained at the lower pitching levels. 相似文献
102.
Ahmet Yalcin Gungor Erhan Ozcan Huseyin Alkis Hakan Turkkahraman 《Journal of Adhesion Science and Technology》2013,27(9):958-964
Introduction: The aim of the study was to determine the effects of sodium ascorbate and delaying bonding for 4 weeks after bleaching on SBS of orthodontic brackets.Methods: Sixty freshly extracted, noncarious, premolars were randomly assigned to 4 groups of 15 each. Orthodontic brackets were bonded with a composite resin and cured with a halogen light. After bonding, the shear bond strengths of the brackets were tested with a universal testing machine. Group I served as the control. In groups II, III, and IV, teeth were bleached with an office bleaching method. In group II, brackets bonded immediately after bleaching. In group III, teeth were immersed in artificial saliva of 4 weeks after bleaching before bonding brackets. In group IV, teeth were treated with 10% sodium ascorbate after bleaching before bonding brackets.Results: One-way analysis of variance indicated a significant difference between groups (P < .001). The highest values for SBS were measured in group I (11.92 ± 0.81 MPa). The SBS was significantly lower in groups II, III, and IV than in group I (P < .001). There was no statistically significant difference between groups III and IV.Conclusions: Bleaching significantly reduced the SBS of orthodontic brackets on human enamel. If bleaching is mandatory, teeth should be treated with sodium ascorbate before bonding. 相似文献
103.
Ni incorporated and Ni–Rh incorporated bimetallic MCM-41 like mesoporous catalysts, which were synthesized following a one-pot hydrothermal procedure, showed very high activity in dry reforming of methane. Among the Ni incorporated catalysts, Ni-MCM-41-V, with a Ni/Si ratio of 0.19, showed the best catalytic performance. Rh incorporation into this catalyst by the one-pot procedure improved both activity and time on stream stability of the catalyst. However, Rh incorporation by impregnation caused instabilities due to coke formation, after about 11 h of reaction time. Occurrence of reverse water gas shift reaction caused higher CO selectivity than H2 selectivity, with the Ni incorporated catalysts. Rh incorporation into these catalysts decreased the relative significance of reverse water gas shift reaction, with respect to dry reforming reaction. 相似文献
104.
Huseyin Yilmaz Gary L. Messing Susan Trolier-McKinstry 《Journal of Electroceramics》2003,11(3):207-215
Textured (Na1/2Bi1/2)TiO3-BaTiO3 (5.5 mol% BaTiO3) ceramics with <100>pc (where pc denotes the pseudocubic perovskite cell) orientation were fabricated by Templated Grain Growth (TGG) and Reactive Templated Grain Growth (RTGG) using anisotropically shaped template particles. In the case of TGG, molten salt synthesized SrTiO3 platelets were tape cast with a (Na1/2Bi1/2)TiO3-5.5 mol%BaTiO3 powder and sintered at 1200°C for up to 12 h. In the RTGG approach, Bi4Ti3O12 (BiT) platelets were tape cast with a Na2CO3, Bi2O3, TiO2, and BaCO3 powder mixture and reactively sintered. The TGG approach using SrTiO3 templates resulted in >90% texture along [001] whereas the RTGG approach using BiT templates resulted in 80% texture. The grain orientation distribution along the textured direction, as measured by X-ray rocking curve, showed a full width at half maximum of 8° and a texture fraction of 80%. 相似文献
105.
106.
This study considers numerical simulation of the combustion of methane with air, including oxygen and nitrogen, in a burner
and the numerical solution of local entropy generation rate due to high temperature and velocity gradients in the combustion
chamber. The effects of equivalence ratio (Φ) and oxygen percentage (γ ) on combustion and entropy generation rates are investigated
for different Φ (from 0.5 to 1.0) andγ values (from 10 to 30%). Combustion is simulated for the fuel mass flow rate resulting in the same heat transfer rate (Q)y
to the combustion chamber in each case. Numerical calculation of combustion is performed individually for all cases with the
use of the Fluent CFD code. Furthermore, a computer program has been developed to calculate the volumetric entropy generation
rate and the other thermodynamic parameters numerically by using the results of the calculations performed with the FLUENT
code. The predictions show that the increase of Φ (or the decrease of λ) significantly reduces the reaction rate levels. Average
temperature in the combustion chamber increases by about 70 and 35% with increase ofγ (from 10 to 30%) and Φ (from 0.5 to 1.0) respectively. With increase ofγ from 10 to 30%, volumetric local entropy generation rate decreases by about 9 and 4% for Φ = 0.5 and 1.0 respectively, while
total entropy generation rate decreases exponentially and the merit numbers increase. The ratio of the rates useful energy
transfer to irreversibility therefore improves as the oxygen percentage increases 相似文献
107.
Huseyin M. Ertunc Kenneth A. Loparo Hasan Ocak 《International Journal of Machine Tools and Manufacture》2001,41(9):2102
Monitoring of tool wear condition for drilling is a very important economical consideration in automated manufacturing. Two techniques are proposed in this paper for the on-line identification of tool wear based on the measurement of cutting forces and power signals. These techniques use hidden Markov models (HMMs), commonly used in speech recognition. In the first method, bargraph monitoring of the HMM probabilities is used to track the progress of tool wear during the drilling operation. In the second method, sensor signals that correspond to various types of wear status, e.g., sharp, workable and dull, are classified using a multiple modeling method. Experimental results demonstrate the effectiveness of the proposed methods. Although this work focuses on on-line tool wear condition monitoring for drilling operations, the HMM monitoring techniques introduced in this paper can be applied to other cutting processes. 相似文献
108.
Huseyin Sehitoglu Ibrahim Karaman X. Zhang Hong Kim Yuriy Chumlyakov I. Kireeva Hans J. Maier 《Metallurgical and Materials Transactions A》2001,32(3):477-489
Single-crystal orientations of NiTi10Cu alloys were studied under incremental, cyclic compression conditions to establish
the pseudoelastic and shape memory response of this class of alloys. This material exhibits a two-step transformation involving
cubic to orthorhombic martensite (B2 → B19) followed by orthorhombic to monoclinic martensite (B19 → B19′). The transformation
parameters (shear magnitudes and directions for habit and twin planes) were determined associated with the B2 → B19 transformation.
The growth of monoclinic martensite correspondent variant pairs (CVPs) emanating from the orthorhombic structure was also
analyzed. The transformation strain for the B2 → B19 case was orientation dependent and lower than the B19 → B19′ transformation
in compression for all orientations except those near the [001] pole. The experimental results show that the critical transformation
stress is orientation dependent and is in the range 30 to 58 MPa. Orientations that exhibit lower transformation stress (or
high resolved shear stress factors, [100] and [012]) produce higher recoverable strains (as high as 4 pct), while other orientations
([011], [111], and [123]) with lower resolved shear stress factors result in recoverable strains less than 3 pct. At higher
strains, inelastic deformation develops, limiting recoverability. The recoverable strains are lower than the theoretical values
for two main reasons: the transformation is curtailed first by austenite slip and subsequently by martensite slip, and the
orthorhombic structure does not fully transform to the monoclinic martensite. 相似文献
109.
110.
A sticky surface of a tape was adhered to a graphite surface and then the tape was peeled off. The insulator tape was coated with thin graphite and became conductive in order to use flexible tape as a current collector. Aniline was electrodeposited onto a flexible tape substrate having graphite layer by electrochemical polymerization method from an aqueous (H2SO4 solution containing aniline monomers) and non-aqueous media (a deep eutectic solvent containing aniline). The prepared polymeric electrodes were characterized by Fourier transform infrared spectroscopy, Raman, thermogravimetric analysis and scanning electron microscopy techniques. The electrochemical properties of coated and uncoated electrodes were also examined by cyclic voltammetry and galvanostatic charge discharge techniques. The polyaniline (PANI) coated tape can be used as a flexible electrode in supercapacitor applications because PANI coated electrodes are highly electroactive in Na2SO4 electrolyte. After 3000 cycles, the capacitance retention of PANI film electrodeposited from Ethaline bath was 90%, while the areal capacitance of PANI film obtained from acidic medium reaches 50% after 500 cycles. As PANI electrode is stable in an ionic liquid for long cycling, Ethaline ionic liquid can be used as electrolyte for PANI based supercapacitor electrode. PANI coated graphite on tape, which is prepared in an easy and inexpensive way is a promising flexible material for high performance supercapacitors. 相似文献