Durable press finishing of cotton fabrics with polycarboxylic acid increases fabric wrinkle-resistance at the expense of its mechanical strength. Severe tensile strength loss is the major disadvantage for wrinkle resi...Durable press finishing of cotton fabrics with polycarboxylic acid increases fabric wrinkle-resistance at the expense of its mechanical strength. Severe tensile strength loss is the major disadvantage for wrinkle resistant cotton fabrics.Tensile strength loss of cotton fabric crosslinked by a polycarboxylic acid can be attributed to depolymerization and crosslink of cellulose molecules. Measurement of the molecular weight of cotton fabric before and after crosslinked by polycarboxylic acids can offer a possibility of direct understanding of the depolymerization. In this research, amultiple angle laser light scattering photometer was used todetermine the absolute molecular weight of cotton fabric treated with BTCA at different pH and then hydrolyzed with 0. 5 M NaOH solution at 50℃ for 144 h. The results indicate that average molecular weights of cotton fabric treated with polycarboxylic acids at different pH are almost the same.展开更多
Objective: To sum up 121 cases of heart disease operations with the help of thoracoscope from May to August in 2000. Among these cases, 48 cases were atrial septal defect (ASD); the average age of patients is 20±...Objective: To sum up 121 cases of heart disease operations with the help of thoracoscope from May to August in 2000. Among these cases, 48 cases were atrial septal defect (ASD); the average age of patients is 20±10 years old; average weight is (43±16) kg. 67 patients with ventricular septal defects (VSD), average age13±9 years old; one male patient, 44 years old with Ebstein malformation; one female patient (21 years old) partial atrioventricular canal combined with cor triatriatum; one male (21 years old) with ruptared aneuryem of aortic sinus. 3 cases(all females ) with mitral stenosis combined with mitral valve incompetence. One male patient(aged 16)with pericardiun effusion after trauma. Methods: During operations, a patient with supine position, and his/her right shoulder was padded 30°higher. Tracheal cannula was inserted and air was piped in with high frequency jet ventilation. Three mini thoracotomies with a diameter of 2 to 3 cm were made in the 4th intercostals space of the right par sternum and the 4th and 7th intercostals spaces of the right middle axillary line respectively. An periphera extra corporeal circulation was made. the aortic clamp was clamped, cannula for cold perfusion. After the heart was sliced and a reformative operation was performed. The process of the operation of defects repairs was finished under the thoracoscope. The other operations were performed with the help of thoracoscope. 3 rheumatic heart disease patients got 25# mechanical mitral valve prosthesis. A 30# tricuspid plasty ring was applied to The Ebstein malformation patient. Results: all 121 patients were successfully operated on without death. Two VSD cases appeared transient third degree atrialventricular block.Because 4 cases had more chest drainage, so they were stanched bleeding twice. After the operation, heart murmur vanished, and ultrasonic inspection showed no diffluence inside the heart. Conclusion: Our experience showed that all atrium, ventricular septal defects can be repaired under the thoracoscope. This scope-assisted technology is more accepted by patients because of tiny incisions and also provides an alternative solution for cardiac surgeons.展开更多
-Two types of filters are widely used to remove semidirunal and diurnal tidal signals and other high frequency noises in oceanography. The first type of filters uses moving average with weights in time domain, and can...-Two types of filters are widely used to remove semidirunal and diurnal tidal signals and other high frequency noises in oceanography. The first type of filters uses moving average with weights in time domain, and can be easily operated. Some data will be lost at each end of the time series, especially for the low low-pass filters. The second type of filters uses the discrete Fourier transform filter (DFTF) which operates in the frequency domain, and there are no data loss at the ends for the forward transform. However, owing to the Gibbs phenomenon and the discrete sampling (Nyquist effect) , ringing appears in the inverse transformed data, which is especially serious at each end. Thus some data at the ends are also discarded. The present study tries to find out what causes the ringing and then to seek for methods to overcome the ringing. We have found that there are two kinds of ringings, one is the Gibbs phenomenon, as defined before. The other is the 'Nyquist'ringing due to sampling Nyquist critical frequency. The former is due to the abrupt transition in frequency band. The Gibbs and Nyquist effects show the ringing at each end of the filtered time series. Thus, the use of a cosine taper or a linear taper on the window in the frequency domain makes the transition band smooth, so that the Gibbs phenomenon will be minimized. Before applying the Fast Fourier Transform (FFT), the original time series at each end is properly tapered by a split cosine bell that reduces significant ringing since this method limits the energy transfer from outside of the Nyquist frequency. Thus, the DFTF can be a powerful tool to suppress the signals in which we are not interested, with sharp peaks in low frequency variation and less data loss at each end.展开更多
基金The Project-sponsored by SRF for ROCS, SEM and EYTP of MOE
文摘Durable press finishing of cotton fabrics with polycarboxylic acid increases fabric wrinkle-resistance at the expense of its mechanical strength. Severe tensile strength loss is the major disadvantage for wrinkle resistant cotton fabrics.Tensile strength loss of cotton fabric crosslinked by a polycarboxylic acid can be attributed to depolymerization and crosslink of cellulose molecules. Measurement of the molecular weight of cotton fabric before and after crosslinked by polycarboxylic acids can offer a possibility of direct understanding of the depolymerization. In this research, amultiple angle laser light scattering photometer was used todetermine the absolute molecular weight of cotton fabric treated with BTCA at different pH and then hydrolyzed with 0. 5 M NaOH solution at 50℃ for 144 h. The results indicate that average molecular weights of cotton fabric treated with polycarboxylic acids at different pH are almost the same.
文摘Objective: To sum up 121 cases of heart disease operations with the help of thoracoscope from May to August in 2000. Among these cases, 48 cases were atrial septal defect (ASD); the average age of patients is 20±10 years old; average weight is (43±16) kg. 67 patients with ventricular septal defects (VSD), average age13±9 years old; one male patient, 44 years old with Ebstein malformation; one female patient (21 years old) partial atrioventricular canal combined with cor triatriatum; one male (21 years old) with ruptared aneuryem of aortic sinus. 3 cases(all females ) with mitral stenosis combined with mitral valve incompetence. One male patient(aged 16)with pericardiun effusion after trauma. Methods: During operations, a patient with supine position, and his/her right shoulder was padded 30°higher. Tracheal cannula was inserted and air was piped in with high frequency jet ventilation. Three mini thoracotomies with a diameter of 2 to 3 cm were made in the 4th intercostals space of the right par sternum and the 4th and 7th intercostals spaces of the right middle axillary line respectively. An periphera extra corporeal circulation was made. the aortic clamp was clamped, cannula for cold perfusion. After the heart was sliced and a reformative operation was performed. The process of the operation of defects repairs was finished under the thoracoscope. The other operations were performed with the help of thoracoscope. 3 rheumatic heart disease patients got 25# mechanical mitral valve prosthesis. A 30# tricuspid plasty ring was applied to The Ebstein malformation patient. Results: all 121 patients were successfully operated on without death. Two VSD cases appeared transient third degree atrialventricular block.Because 4 cases had more chest drainage, so they were stanched bleeding twice. After the operation, heart murmur vanished, and ultrasonic inspection showed no diffluence inside the heart. Conclusion: Our experience showed that all atrium, ventricular septal defects can be repaired under the thoracoscope. This scope-assisted technology is more accepted by patients because of tiny incisions and also provides an alternative solution for cardiac surgeons.
文摘-Two types of filters are widely used to remove semidirunal and diurnal tidal signals and other high frequency noises in oceanography. The first type of filters uses moving average with weights in time domain, and can be easily operated. Some data will be lost at each end of the time series, especially for the low low-pass filters. The second type of filters uses the discrete Fourier transform filter (DFTF) which operates in the frequency domain, and there are no data loss at the ends for the forward transform. However, owing to the Gibbs phenomenon and the discrete sampling (Nyquist effect) , ringing appears in the inverse transformed data, which is especially serious at each end. Thus some data at the ends are also discarded. The present study tries to find out what causes the ringing and then to seek for methods to overcome the ringing. We have found that there are two kinds of ringings, one is the Gibbs phenomenon, as defined before. The other is the 'Nyquist'ringing due to sampling Nyquist critical frequency. The former is due to the abrupt transition in frequency band. The Gibbs and Nyquist effects show the ringing at each end of the filtered time series. Thus, the use of a cosine taper or a linear taper on the window in the frequency domain makes the transition band smooth, so that the Gibbs phenomenon will be minimized. Before applying the Fast Fourier Transform (FFT), the original time series at each end is properly tapered by a split cosine bell that reduces significant ringing since this method limits the energy transfer from outside of the Nyquist frequency. Thus, the DFTF can be a powerful tool to suppress the signals in which we are not interested, with sharp peaks in low frequency variation and less data loss at each end.
