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71.
Osteosclerosis due to endemic fluorosis 总被引:2,自引:0,他引:2
Tamer MN Kale Köroğlu B Arslan C Akdoğan M Köroğlu M Cam H Yildiz M 《The Science of the total environment》2007,373(1):43-48
Endemic water borne fluorosis is a public health problem in Isparta, a city located in southern Turkey. In order to investigate the association between osteosclerosis and fluorosis, we retrospectively screened the results of lumbar spine and femur neck bone mineral density (BMD) of 1500 patients who were examined before, for any reason in between 2001-2003. Sixty nine patients (67 females and 2 males, mean age 52.6+/-10.2) with vertebra T-scores>or=+2 were found only except a patient with osteoid osteoma in the femur neck (femur T-score+6.64). Thirty-four of the patients could be reexamined with lateral vertebra BMD and investigated for fluorosis and the other etiologic causes of osteosclerosis. Of 34 patients, 14 had either mottled tooth enamel or urine fluoride level greater than 1.5 mg/l. Other etiologic causes were hypothyroidism (2), hypoparathyroidism (1), history of lumbar fracture (1), use of retinoids (1), vitamin D (7), oral calcium preparations (9), and bisphosphanates (3). Lateral lumbar vertebral T-score was greater than+2 in 12 patients (35.3%). Femur T-score was greater than+2 in 7 patients (20.6%). Fourteen patients (41.2%) had lateral vertebral or femur T-score>or=+2. Five (35.7%) of these patients had signs of fluorosis, as discussed before. Mean body mass index of individuals with fluorosis was 36.4+/-7.9 and this result was significantly higher than other osteosclerotic subjects (31.6+/-4.4). In conclusion we believe that approximately one third of the osteosclerosis in our region was due to endemic skeletal fluorosis and obesity may enhance this osteosclerotic type bone changes in endemic fluorosis. 相似文献
72.
The amount of retained austenite in the quenched cold work tool steel sample is 17.7%, in the condition of sub-zero heat treated and double tempered samples following by quenching is 1.9% determined by XRD analysis. The types of carbides (MC, M7C3, M23C6) present in the structure was determined by XRD and SEM-EDS analysis. The hardness of test samples were 865 HV(0.1) for quenched sample and 785 HV(0.1) forth sample subjected to sub-zero treatment and double tempered after the quenching. 相似文献
73.
Fuel properties of rapeseed oil and soybean oil methyl esters (e.g. density, cetane number and viscosity etc.) are similar to those of the diesel fuel. These methyl esters can be used as diesel engine fuel by mixing withy diesel fuel. In this study a comparison of diesel fuel, the rapeseed oil methyl ester and the soybean oil methyl ester was made from the engine performance and emissions point of view. The tests were carried out with a four-cylinder diesel engine for tree different injection pressures such as 250, 300 and 350 bar with each of these fuels. For the purpose of comparison, tests were also conducted at full load conditions with diesel fuel. As the result, the performance and emission values of rapeseed oil (R) and soybean oil (S) methyl esters were found to be nearly the same with those of diesel fuels (D) when injection pressure was increased to 300 bar. 相似文献
74.
75.
Continuous production of palm methyl esters 总被引:4,自引:0,他引:4
A system for continuous transesterification of palm oil was developed using a continuous stirred-tank reactor (CSTR) and pumps
for continuous delivery of oil and catalyst and for continuous removal of product. Potassium hydroxide was used as the catalyst,
the methanol-to-oil molar ratio was 6∶1, and reaction temperature was 60°C. The yield of methyl esters increased from 58.8%
of theoretical yield at a residence time of 40 min to 97.3% at a residence time of 60 min. However, higher residence times
decreased the production rate. During long-term continuous operation, the CSTR displayed steady state conditions in terms
of product profile and methyl ester concentration. This process has good potential in the manufacture of biodiesel. 相似文献
76.
Mulder J. Ward C.M. Chi-Hung Lin Kruse D. Westra J.R. Lugthart M. Arslan E. van de Plassche R.J. Bult K. van der Goes F.M.L. 《Solid-State Circuits, IEEE Journal of》2004,39(12):2116-2125
This paper presents an 8-b two-step subranging analog-to-digital (ADC) using interpolation, averaging, offset compensation, and pipelining techniques to accomplish an effective number of bits of 7.6 b at 125 MSample/s. The 0.13-/spl mu/m CMOS ADC occupies 0.09 mm/sup 2/ and consumes 21 mW. 相似文献
77.
In this letter, Doppler spread estimation in digital mobile radio systems is described. A maximum-likelihood approach is derived, and used to develop suboptimal approaches with lower complexity. The proposed algorithms rely on periodic channel estimation and can be used in both TDMA and CDMA systems 相似文献
78.
Iftikhar Ahmad Javid H Zaidi Rizwan Hussain Arshad Munir 《Polymer International》2007,56(12):1521-1529
A series of blocked diisocyanates has been synthesized from toluene diisocyante (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 4,4′‐diphenylmethane diisocyanate (MDI) and 2‐butoxyethanol. The synthesis of blocked diisocyanate adducts was confirmed by Fourier transform infrared, 1H NMR, electron impact mass spectrometry and nitrogen analysis. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and carbon dioxide evolution were used to determine the minimum de‐blocking temperatures. De‐blocking temperatures determined by these three techniques were found to be in the order DSC > TGA > CO2 evolution. The effect of different metal catalysts on thermal de‐blocking reaction of the blocked diisocyanates was studied, using the carbon dioxide evolution method. It was found that iron(III) oxide has the maximum catalytic activity on de‐blocking. The solubility of the blocked diisocyanate adducts was determined in different solvents. The study revealed that at 30 °C blocked IPDI and HDI adducts show better solubility than adducts based on TDI and MDI. Isocyanate‐terminated prepolymers of blocked diisocyanates and hydroxyl‐terminated polybutadiene (HTPB) were prepared. The storage stability and gelation times of the prepolymers were studied. Results showed that all the diisocyanate‐HTPB compositions are stable at 50 °C for more than three months. However, aliphatic diisocyanate‐HTPB compositions require greater gelation time than aromatic diisocyanate‐HTPB compositions at their respective de‐blocking temperatures. Copyright © 2007 Society of Chemical Industry 相似文献
79.
Summary The modeling of deformation in flexible multibody systems is still under intensive investigation. While the floating frame
of reference formulation has become a standard for the modeling of deformable moving bodies, formulations based on absolute
coordinates are comparatively new. The recently developed absolute nodal coordinate formulation uses solely nodal position
and slopes as degrees of freedom for structural elements. The numerical treatment is similar to the absolute coordinate formulation,
which is investigated in the following. An efficient formulation based on absolute coordinates with a reduced strain tensor
(similar to corotational formulations) has been derived recently, and the analogy to the floating frame of reference formulation
has been shown. The efficiency of this formulation is based on a co-rotated stiffness matrix which is factorized only once,
however, only linear constraints have been treated up to now. The present paper treats the extension of the advantages of
the co-rotated formulation with respect to nonlinear constraints, damping and contact. Constraints are discussed for the special
cases of linear and nonlinear dependence on the deformation degrees of freedom. The (implicit) Newmark scheme is used to illustrate
the time stepping procedure within the present method. In the case of a small number of nonlinear constraints, a single time
step can be performed by solving only a small system of nonlinear equations by means of Newton's method. A numerical example
shows a method to reduce the number of constraints and illustrates the computational advantages of the proposed method. 相似文献
80.