Investigation of structural, thermal, and electrical characteristics of zirconium-doped lithium-phosphate glasses.

Zirconium-lithium-phosphate glasses were elaborated through the melting-quenching technique. The primary objective of this research is to investigate how the replacement of lithium oxide with zirconium oxide impacts the physical, thermal, mechanical, and electrical properties of the fabricated glasses. The result showed that the vitreous materials were obtained with a ZrO2 content lower than 1 mol%. Furthermore, it is found that incorporating ZrO2 in the glassy phosphate framework affects mal compatibility and increases the durability of the glassy samples. Analyzing the mechanical performance reveals that the incorporation of ZrO2 leads to enhancements in the elastic constants of the glasses, including the longitudinal modulus, shear modulus, Young's modulus, bulk modulus, and Poisson coefficient. The bond strengths are used to calculate and explain the glasses' Vickers hardness values. On the other hand, the infrared (IR) spectroscopy results reveal that replacing Li2O with ZrO2 oxide in the glassy matrix causes significant structural changes. Finally, the dielectric features of the prepared glasses versus frequency and temperature are analyzed. The significance lies in the fact that the replacement of lithium with zirconium leads to a reduction in the ionic conductivity of the glasses.

Effect of the Na2O-Nb2O5-P2O5 glass additive on the structure, dielectric and energy storage performances of sodium niobate ceramics.

A phosphate glass Na2O-Nb2O5-P2O5 (NPP) is incorporated into NaNbO3 (NN) ceramics to examine its impact on the density, rearrangement of structural units, dielectric and energy storage features of the elaborated composites. The sodium niobate ceramic (NN) is prepared using the solid state process, whereas, the Na2O-Nb2O5-P2O5 (NPP) glasses are produced using the method of conventional melt quenching. The glass (NPP) is added to the ceramic (NN) according to the composition (100-x) NN-xNNP; (x = 0, 2.5, 5, and 7.5 %wt). The developed composites are denoted as NN-Gx where x represents the content of glass in %wt. The appropriate sintering temperature for the glass-ceramic composites was measured based on the density measurements. It was found that with the addition of glass, their density was decreased and their fritting at lower temperatures was enhanced. The obtained SST for all composites is about 900 °C. After the densification stage, Raman spectroscopy, X-ray Diffraction, Granulo-laser analysis, and scanning electron microscopy are examined to study the structural approach and the morphology of sintered NN-Gx composites. The NN-G5 composite was found to have a fine grain microstructure that was uniform. The dielectric features of the composite revealed that at ambient temperature the NN-G5 had the greatest dielectric constant. The energy storage performance of the composite was investigated from the P-E plots and the parameters of energy storage. Based on the obtained results, it was concluded that incorporating up to 5% wt. of NNP glass in sodium niobate ceramics positively affects their dielectric and energy storage performances.

High temperature and composition induced phase transitions in LiZnV1-xAsxO4 phenacites: Crystal structure and Raman spectroscopy studies.

In this work, using techniques of X-ray diffraction and Raman spectroscopy, we report the composition and high-temperature induced phase transition in the system LiZnV1-xAsxO4 (0⩽x⩽1). Both techniques showed that the increase of arsenic amount induced a structural transition from R-3 LiZnVO4 type to LiZnAsO4 type belonging to R3 space group, the transition occurring between x=0.7 and x=0.8. Furthermore, increasing temperature for the compositions (0.8⩽x⩽1) manifests a transition from the LiZnAsO4 structural type with R3 space group to the R-3 LiZnVO4 structural type. For this series, the transition from the space group R3 to the centro-symmetric space group R-3 shows considerable changes in the compositional and temperature dependencies of the bands: spectral positions of all the observed Raman bands exhibit shifts linearly proportional to the temperature increase, with points of shift-rate changes revealing a symmetry change. The Raman-spectra based temperature-composition phase diagram confirms the results obtained using the method of Rietveld refinements, thus showing the R-3 to R3 transition occurring between x=0.7 and 0.8.

Blood pressure and age associated with silent autonomic dysreflexia during urodynamic examinations in patients with spinal cord injury.

STUDY DESIGN: An observational study. OBJECTIVES: To investigate the factors associated with silent autonomic dysreflexia (AD) during urodynamics (UD) in spinal cord injury (SCI) patients. SETTING: Taichung city, Taiwan, ROC. METHODS: Blood pressure (BP) and symptoms of AD were continuously monitored during UD, and systolic blood pressure (SBP) elevations >20 mmHg was considered an AD reaction. AD patients were divided into a symptomatic group and a silent group (without AD symptoms), and variables (basic demographic data, hemodynamic data and UD parameters) were compared. RESULTS: A total of 42 patients, 21 in symptomatic and 21 in silent AD groups, were analyzed. Symptomatic group had significantly greater diastolic blood pressure (DBP) increment and rates of SBP/DBP changes (change of BP divided by duration) as compared to the silent group (29.5 vs 21.7 mmHg; 4.8 vs 2.3 mmHg min(-1) and 2.8 vs 1.4 mmHg min(-1)) (P<0.05). The cutoff points of these three variables, determined by receiver operating characteristic analysis, are: DBP increment of 21 mmHg and rates of SBP/DBP change of 2.27 and 1.16 mmHg min(-1). Age had a weak negative correlation with DBP change (Pearson's r=-0.377, P=0.048) and the silent group was significantly older than the symptomatic group (49.4 vs 40.1 years, P<0.05). CONCLUSION: Patients with more symptomatic AD tended to have significant DBP elevation and more rapid SBP/DBP increments, and this was negatively correlated with age. Aging decreases AD symptoms and the magnitude of DBP elevation, possibly through the mechanism of decreased baroreceptor sensitivity. BP monitoring during UD and other invasive procedures is strongly recommended, especially for elderly SCI patients.

Use of sonography and radioisotope renography to diagnose hydronephrosis in patients with spinal cord injury.

OBJECTIVE: To study the accuracy of sonography and radioisotope renography in detecting hydronephrosis in patients with spinal cord injury (SCI). DESIGN: Prospective, blinded comparison study. SETTING: Rehabilitation hospital affiliated with a medical college. PARTICIPANTS: One hundred and nine patients with SCI (21 women, 88 men) participated. INTERVENTIONS: Comprehensive urologic examinations including clinical evaluation, laboratory tests, intravenous urography (IVU), sonography, radioisotope renography (renal scan), voiding cystourethrography, and cystometry. The findings at sonography and renal scan were separately compared with the final diagnosis interpreted by IVU and clinical findings. MAIN OUTCOME MEASURES: Effective renal plasma flow, pyelocaliectasis, and positive and negative predictive value. RESULTS: A total of 235 kidneys were analyzed. Sonography correctly excluded the presence of hydronephrosis in 173 of 192 nonobstructed kidneys. Sonograms were interpreted as positive in 41 of 43 kidneys with documented hydronephrosis. Renal scan correctly excluded 161 nonobstructed kidneys. The renal scan detected 39 of 43 kidneys with hydronephrosis. The sensitivity of sonography was.96 with a specificity of.90. Renal scan reached a sensitivity of.91 with a specificity of.84. CONCLUSION: Sonography and renal scan are safe, sensitive, and specific for detecting hydronephrosis. Combined use of both methods appears to be a reliable alternative to IVU in the long-term follow-up for patients with SCI with neurogenic bladder dysfunction.

Tc-99m MAG3 renal studies: renogram and effective renal plasma flow in spinal cord injury patients.

To determine whether years since injury, level of injury, degree of injury, gender, or age influence renal function in 66 spinal cord injuries (SCI) patients without urological complications, individual kidney effective renal plasma flow (ERPF) and radionuclide renogram (RR) were measured using technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3). The 176 individual kidneys included 84 kidneys with normal ERPF and RR, 48 kidneys with normal ERPF but abnormal RR, and 44 kidneys with abnormal ERPF and RR. The incidence of abnormal Tc-99m renal study results was higher in the kidneys of female patients (37/54, 68%) than of male patients (55/122, 45%) (p < 0.05). We found that Tc-99m MAG3 renal studies including ERPF and RR are safe and noninvasive urological screening tests for SCI patients.

Bladder shape impact on the accuracy of ultrasonic estimation of bladder volume.

OBJECTIVE: Variations in bladder shape can lead to errors in ultrasonic estimation of the bladder volume. The purposes of this study were to compare the accuracies of various formulas to estimate bladder volume from sonographic measurements and to assess the impact of bladder shape on the accuracy of bladder volume estimation. STUDY DESIGN: Twenty-four healthy volunteers (13 men, 11 women) and 55 spinal cord injury patients (48 men, 7 women) underwent ultrasonographic measurements of dimensions before and after voiding. Bladder shape was classified as cuboid, ellipsoid, or triangular prism. Ten formulas from the literature were applied to estimate bladder volume, using the volume voided or catheterized as the standard, and then linear regression was used to obtain optimal correction coefficients for the whole data set as well as each of the three bladder shapes. SETTING: Rehabilitation hospital affiliated with a medical college. RESULTS: The most accurate of the 10 formulas tested was height (H) X transverse depth (Dt) x weight (W) x 0.7 (mean error 17.4%+/-11.6%). Linear regression analysis yield optimal correction coefficients of .72 for the whole data set and .89, .81, and .66 for cuboidal, ellipsoid, and triangular prism-shaped bladders, respectively. The mean error for the estimation of bladder volume using .72 as the correction coefficient was 16.9%+/-11.9% and decreased to 12.7%+/-10.1% (p < .0001, paired t test) when the bladder shape was taken into account. CONCLUSION: Using bladder shape for reference and applying the corresponding correction coefficient to volume calculations will improve the accuracy of the estimation.

Sonographic diagnosis of hydronephrosis in patients with spinal cord injury: influence of bladder fullness.

OBJECTIVE: To investigate and compare the diagnostic accuracy of prevoid and postvoid renal sonography in detecting hydronephrosis in patients with spinal cord injury. STUDY DESIGN: A prospective, blind comparison of renal sonography and excretory urography in 67 spinal cord injury patients who underwent periodic urologic examinations. Renal sonography was performed twice, once when the patient's bladder was physiologically full (prevoid) and again when it was just emptied (postvoid). RESULTS: Of 140 kidneys, 24 from 16 patients were found to have hydronephrosis by excretory urography; 116 kidneys had normal urogram findings. Prevoid sonography missed the diagnosis of hydronephrosis in one kidney and showed hydronephrosis in 18 kidneys that had normal results on excretory urography (sensitivity, 95.8%; specificity, 84.5%; negative predictive value, 99.0%). The postvoid sonograms did not detect hydronephrosis in four kidneys and showed hydronephrosis in six kidneys that had normal results on excretory urography (sensitivity, 83.3%; specificity, 94.8%; negative predictive value, 96.5%). Compared to excretory urography, renal sonography detected eight more upper urinary tract abnormalities, which were confirmed by cystograms or radioisotopic renograms. CONCLUSION: Performing renal sonography while the bladder is full can increase the sensitivity in detecting hydronephrosis in asymptomatic spinal cord injured patients.

Application of radioisotope renography with technetium-99m mercaptoacetyltriglycine on patients with spinal cord injuries.

The effectiveness of radioisotope renography with Technetium-99m (Tc-99m) mercaptoacetyltriglycine (MAG3) to provide possible routine urological follow-up was evaluated for the spinal cord injury (SCI) population. Sixty-six SCI patients were examined with radioisotope renography and renal ultrasonography. Excretory urography was done on 46 patients and voiding cystourethrography was done on 46 patients and voiding cystourethrography was done on 59 patients. The time-activity curve patterns of renography were classified into six groups. Curves A were normal. Curves B and C showed various excretion delay but normal effective renal plasma flow (ERPF). Curves D, E, and F showed definite decreased ERPF and excretion delay of different severity. The respective incidence of upper urinary tract complications were 12.0% (10/83) for A, 68.2% (15/22) for B, 100% (4/4) for C, 100% (8/8) for D, 100% (11/11) for E, and 100% (4/4) for F curves. The sensitivity of radioisotope renography was 83.9%, and the specificity was 92.0% in detecting the upper urinary tract complications. There was no adverse effect after 80 renography examinations on 66 SCI patients. As excretion delay occurred in the earlier stage of renal dysfunction, followed by decrease of ERPF, the abnormal time-activity curves can be sensitive indicators to subject SCI patients with early renal deterioration for further urodynamic and morphological studies. For patients with normal renograms, conventional uroradiological studies are not recommended because they are more invasive, cumbersome, and have more side effects as well as higher radiation exposure. We found that radioisotope renography with Tc-99m MAG3 is a safe, noninvasive, sensitive, and valuable urological screening test for SCI patients.

The rehabilitation of pressure sores after myocutaneous flap surgery.

Fourteen myocutaneous flap operations for the treatment of pressure sores were performed from June 1984 to May 1986. After surgery, the patient was immobilized in a prone position in order to avoid direct pressure on the flap and to minimize motion of the hips. When the daily drainage from the wound was less than 10ml, the drain was removed. Hip flexion and body turning every 2 hours (except direct pressure on the flap) were started the day after the removal of the drain. In the meanwhile, a 2-5kg sandbag was placed on the flap until the flap showed mild redness which disappeared within 10 minutes. Under close observation, the duration increased step by step till the flap could tolerate compression for 2 hours continuously. Then the patient was allowed to assume a position with the body weight directly on the flap. Each session of pressure training lasted only until the flap showed mild redness and faded away quickly. The pressure training was finished when the flap was able to tolerate the patient's body weight for approximately 2 hours. The results showed that the myocutaneous flap could bear weight as normal skin 18.5 +/- 5.3 days after the operation; the average duration of hospitalization for treating one sore with a myocutaneous flap was 28.2 +/- 8.7 days. The time involved in pressure training after a myocutaneous flap operation may progress more quickly than that after a conventional skin flap operation.