The lignin-cellulosic texture of wood was used to produce two-dimensional （2D） carbon/carbon （C/C） composites using coal tar pitch. Ash content tests were conducted to select two samples among the different kinds ...The lignin-cellulosic texture of wood was used to produce two-dimensional （2D） carbon/carbon （C/C） composites using coal tar pitch. Ash content tests were conducted to select two samples among the different kinds of woods present in lran, including walnut, white poplar, cherry, willow, buttonwood, apricots, berry, and blue wood. Walnut and white poplar with ash contents of 1.994wt% and 0.35 lwt%, respectively, were selected. The behavior of these woods during pyrolysis was investigated by differential thermal analysis （DTA） and thermo gravimetric （TG） analysis. The bulk density and open porosity were measured after carbonization and densification. The mierostruc- tural characteristics of samples were investigated by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, and Fourier-transform infrared （FT-IR） spectroscopy. The results indicate that the density of both the walnut and white poplar is increased, and the open porosity is decreased with the increasing number of carbonization cycles. The XRD patterns of the wood charcoal change gradually with increasing py- rolysis temperature, possibly as a result of the ultra-structural changes in the charcoal or the presence of carbonized coal tar pitch in the composite＇s body.展开更多
Background: An irreversible renal function impairment is called chronic renal failure (CRF) which finally leads to the “end-stage renal disease” (ESRD) and requires renal replacement therapies. The aim of this study...Background: An irreversible renal function impairment is called chronic renal failure (CRF) which finally leads to the “end-stage renal disease” (ESRD) and requires renal replacement therapies. The aim of this study is to evaluate the incidence, prevalence of epidemiological indicators (age, sex), and causes of chronic renal failure in children in Mashhad (one of the big cities of Iran). Methods: This is a cross-sectional study that was conducted on patients’ records over a seven-year period (2008-2014) in Doctor Sheikh Children’s Hospital of Mashhad. The inclusion criteria were all children under 20 years old diagnosed with ESRD, with a GFR less than 15 ml/min/1.73 m2 who were referred to the hospital during the study period. Patients’ information, such as age, gender, onset of dialysis, causes of constructing renal failure, and positive or negative antigen of hepatitis B was extracted from their records. Data were analyzed using SPSS 16 software. Results: A total of 326 patients were studied, of which, 56.4% were male. 45.1% were from 7 to 18 years. 56.4% of patients were on hemodialysis and others were on peritoneal dialysis. The most common cause of chronic renal failure in the study was respectively reflux nephropathy (32.9%), nephrotic syndrome (8.9%), neurogenic bladder (5.5%), stones (2.5%), glomerulopathy (2.1%) and cystinosis (1.5%) and (20.9%) had unknown cause. During the 7-year period of study considering the treatment outcomes, 69.3% of patients needed to continue the dialysis;10.4% underwent transplantation;10.4% unfortunately died despite of treatment and 1.5% were cured. Conclusions: It is hoped that considering the clinical symptoms of children with chronic renal failure and the diagnosis of the cause, we can reduce complications of the disease with a quick diagnosis and treatment, as well as appropriate follow-up.展开更多
文摘The lignin-cellulosic texture of wood was used to produce two-dimensional （2D） carbon/carbon （C/C） composites using coal tar pitch. Ash content tests were conducted to select two samples among the different kinds of woods present in lran, including walnut, white poplar, cherry, willow, buttonwood, apricots, berry, and blue wood. Walnut and white poplar with ash contents of 1.994wt% and 0.35 lwt%, respectively, were selected. The behavior of these woods during pyrolysis was investigated by differential thermal analysis （DTA） and thermo gravimetric （TG） analysis. The bulk density and open porosity were measured after carbonization and densification. The mierostruc- tural characteristics of samples were investigated by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, and Fourier-transform infrared （FT-IR） spectroscopy. The results indicate that the density of both the walnut and white poplar is increased, and the open porosity is decreased with the increasing number of carbonization cycles. The XRD patterns of the wood charcoal change gradually with increasing py- rolysis temperature, possibly as a result of the ultra-structural changes in the charcoal or the presence of carbonized coal tar pitch in the composite＇s body.
文摘Background: An irreversible renal function impairment is called chronic renal failure (CRF) which finally leads to the “end-stage renal disease” (ESRD) and requires renal replacement therapies. The aim of this study is to evaluate the incidence, prevalence of epidemiological indicators (age, sex), and causes of chronic renal failure in children in Mashhad (one of the big cities of Iran). Methods: This is a cross-sectional study that was conducted on patients’ records over a seven-year period (2008-2014) in Doctor Sheikh Children’s Hospital of Mashhad. The inclusion criteria were all children under 20 years old diagnosed with ESRD, with a GFR less than 15 ml/min/1.73 m2 who were referred to the hospital during the study period. Patients’ information, such as age, gender, onset of dialysis, causes of constructing renal failure, and positive or negative antigen of hepatitis B was extracted from their records. Data were analyzed using SPSS 16 software. Results: A total of 326 patients were studied, of which, 56.4% were male. 45.1% were from 7 to 18 years. 56.4% of patients were on hemodialysis and others were on peritoneal dialysis. The most common cause of chronic renal failure in the study was respectively reflux nephropathy (32.9%), nephrotic syndrome (8.9%), neurogenic bladder (5.5%), stones (2.5%), glomerulopathy (2.1%) and cystinosis (1.5%) and (20.9%) had unknown cause. During the 7-year period of study considering the treatment outcomes, 69.3% of patients needed to continue the dialysis;10.4% underwent transplantation;10.4% unfortunately died despite of treatment and 1.5% were cured. Conclusions: It is hoped that considering the clinical symptoms of children with chronic renal failure and the diagnosis of the cause, we can reduce complications of the disease with a quick diagnosis and treatment, as well as appropriate follow-up.
