Grain size dependent high-pressure elastic properties of ultrafine micro/nanocrystalline grossular.

We have performed sound velocity and unit cell volume measurements of three synthetic, ultrafine micro/nanocrystalline grossular samples up to 50 GPa using Brillouin spectroscopy and synchrotron X-ray diffraction. The samples are characterized by average grain sizes of 90 nm, 93 nm and 179 nm (hereinafter referred to as samples Gr90, Gr93, and Gr179, respectively). The experimentally determined sound velocities and elastic properties of Gr179 sample are comparable with previous measurements, but slightly higher than those of Gr90 and Gr93 under ambient conditions. However, the differences diminish with increasing pressure, and the velocity crossover eventually takes place at approximately 20-30 GPa. The X-ray diffraction peaks of the ultrafine micro/nanocrystalline grossular samples significantly broaden between 15-40 GPa, especially for Gr179. The velocity or elasticity crossover observed at pressures over 30 GPa might be explained by different grain size reduction and/or inhomogeneous strain within the individual grains for the three grossular samples, which is supported by both the pressure-induced peak broadening observed in the X-ray diffraction experiments and transmission electron microscopy observations. The elastic behavior of ultrafine micro/nanocrystalline silicates, in this case, grossular, is both grain size and pressure dependent.

Communication: strong excitonic and vibronic effects determine the optical properties of Li2O2.

The band structure and optical absorption spectrum of lithium peroxide (Li(2)O(2)) is calculated from first-principles using the G(0)W(0) approximation and the Bethe-Salpeter equation, respectively. A strongly localized (Frenkel type) exciton corresponding to the π(∗)→σ(∗) transition on the O(2)(-2) peroxide ion gives rise to a narrow absorption peak around 1.2 eV below the calculated bandgap of 4.8 eV. In the excited state, the internal O(2)(-2) bond is significantly weakened due to the population of the σ(∗) orbital. As a consequence, the bond is elongated by almost 0.5 Å leading to an extreme Stokes shift of 2.6 eV. The strong vibronic coupling entails significant broadening of the excitonic absorption peak in good agreement with diffuse reflectance data on Li(2)O(2) which shows a rather featureless spectrum with an absorption onset around 3.0 eV. These results should be important for understanding the origin of the high potential losses and low current densities, which are presently limiting the performance of Li-air batteries.

Elastic relaxations associated with the Pm3m-R3c transition in LaAlO(3): I. Single crystal elastic moduli at room temperature.

Values for all six independent components of the 3m elastic modulus tensor of LaAlO(3) perovskite are reported. These were determined by means of Brillouin scattering measurements of acoustic velocities in single crystal plates cut parallel to (110) and (100), as defined with respect to the cubic parent structure, and by pure-mode longitudinal and transverse sound velocity measurements along [100], [110] and [111] directions using GHz pulse-echo ultrasonics. The crystals contained intimate intergrowths of twins arising from the Pm3m <--> R3c transition at higher temperature but, in combination with a careful analysis of twin orientation relationships, the two sets of data have allowed a unique solution to be obtained for individual twin components. The new data set represents an important contribution to the characterization of LaAlO(3) single crystals which are widely used as the substrate for a plethora of different thin films with technological applications.

Elastic relaxations associated with the Pm3m-R3c transition in LaAlO(3): II. Mechanisms of static and dynamical softening.

Brillouin spectra have been collected in situ at temperatures up to ∼1000 K for different crystallographic directions from two single crystal plates of LaAlO(3) perovskite. Elastic moduli derived from these, together with heat capacity, spontaneous strain and Raman data from the literature, have then been used to calibrate the coefficients in a classical Landau free energy expansion for the second order [Formula: see text] phase transition at T(c) = 817 K. The static strain/order parameter coupling model provides a quantitative description of elastic softening between room temperature and ∼700 K, but from ∼700 K up to T(c) additional elastic softening correlates with the development of a central peak in the Brillouin spectra. The presence of quasi-elastic scattering, which reaches maximum intensity ∼5-15 K below T(c), implies a strong dynamical component to the phase transition. Relaxation times estimated from the width of the central peak are of the order of ∼10-100 ps and appear to be more or less constant between ∼700 and 800 K, which is consistent with an intrinsic origin associated with phonon density fluctuations. Central peak width variations and an irregular pattern of acoustic velocity variations in a 20 K temperature interval below T(c) are interpreted in terms of flipping of clusters of tilted octahedra between different ⟨111⟩, ⟨011⟩ and ⟨001⟩ tilt axes. The additional softening beyond that expected from the classical strain/order parameter coupling model can be understood in terms of coupling of acoustic modes with the central peak mode(s).

Dexamethasone compared with betamethasone for glucocorticoid treatment of postpartum HELLP syndrome.

OBJECTIVES: To compare the efficacy of dexamethasone and betamethasone to ameliorate the course of postpartum hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome. METHODS: A prospective, mixed randomized/non-randomized clinical investigation of patients with postpartum HELLP syndrome. Treatment with either dexamethasone or betamethasone was continued until there was evidence of disease recovery. RESULTS: Baseline characteristics of both the dexamethasone (n=18) and betamethasone (n=18) groups were similar. Although the time to discharge from the obstetrical recovery room was not statistically significant between groups, reduction in mean arterial blood pressure was more pronounced in the dexamethasone group as compared with the betamethasone group (-15.3+/-1.4 mmHg vs. -7.5+/-1.4 mmHg, respectively, P<0.01). Patients in the dexamethasone group required less antihypertensive treatment than the betamethasone group (6% vs. 50%, P=0.01) and also had a decreased need for readmission to the obstetrical recovery room (0% vs. 22%, P=0.03). CONCLUSION: This investigation supports the use of dexamethasone as the superior glucocorticoid to use for patients with postpartum HELLP syndrome.

A prospective, randomized trial comparing the efficacy of dexamethasone and betamethasone for the treatment of antepartum HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome.

OBJECTIVE: This study was undertaken to determine whether dexamethasone or betamethasone is superior for the antepartum treatment of HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome. STUDY DESIGN: This prospective, randomized, clinical investigation compared intravenously administered dexamethasone and intramuscularly administered betamethasone in the treatment of gravid women with HELLP syndrome. Efficacy end points included laboratory values (platelet count, lactate dehydrogenase activity, aspartate aminotransferase activity) and clinical parameters (mean arterial pressure, urinary output). RESULTS: Forty patients were enrolled in the study, 19 in the dexamethasone arm and 21 in the betamethasone arm. The adjusted time-averaged changes from baseline were significant for aspartate aminotransferase activity (dexamethasone, -20.4 +/- 9.6 U/L; betamethasone, 9.9 +/- 8.9 U/L; P =.029), mean arterial pressure (dexamethasone, -15.6 +/- 1.4 mm Hg; betamethasone, -8.1 +/- 1.4 mm Hg; P <.001), and urinary output (dexamethasone, 12.9 +/- 8.6 mL/h; betamethasone, -11.9 +/- 8.2 mL/h; P =.043). CONCLUSION: Intravenously administered dexamethasone appears to be more effective than intramuscularly administered betamethasone for the antepartum treatment of mothers with HELLP syndrome.

Membrane sweeping versus dinoprostone vaginal insert in the management of pregnancies beyond 41 weeks with an unfavorable cervix.

OBJECTIVE: To determine the best method of cervical ripening to prevent postdate inductions in women with an unfavorable cervix at 41 weeks' gestation. STUDY DESIGN: Women presenting at 41 weeks' gestation with a Bishop score of < or = 4 received daily dinoprostone (Cervidil) vaginal inserts (group I) or daily membrane sweeping (group II). RESULTS: One-hundred and eighty-two women were prospectively randomized with 91 women in each arm. The women in group II, membrane sweeping, had Bishop scores significantly greater on admission for delivery (p < 0.001), had less time elapsed from admission to delivery (p = 0.018), and had fewer labor inductions at 42 weeks (p = 0.04) than the women in group I, the dinoprostone group. In addition, a greater number of women in group II were admitted in spontaneous labor (p = 0.006) than in group I. Total antenatal costs for the membrane sweeping group was $15,120 versus $59,540 for the dinoprostone group. CONCLUSION: Daily membrane sweeping was more effective than dinoprostone administration with fewer postdate inductions at one-fourth the cost.

Effect of amniotic fluid volume on neonatal outcome in diamniotic twin pregnancies.

PROBLEM: We assessed neonatal outcome of normal diamniotic twin pregnancies with known amniotic fluid (AF) volume. METHOD: The AF volume was empirically determined in 39 diamniotic twin gestations. The neonates were stratified by AF volume and evaluated for clinical outcome, gestational age, lecithin-sphingomyelin (L/S) ratio, and birth weight. RESULTS: Neonatal complications did not significantly differ among infants delivered from pregnancies with low (155 to 404 mL), moderate (405 to 807 mL), or high (808 to 5,430 mL) volumes of AF. Relatively constant volumes of AF were maintained throughout the 27 to 38 week range of gestational age, with no apparent correlation between AF volume and gestational age. Variations in the L/S ratio and newborn birth weights were also independent of AF volume. Gestational age was the only significant determinant of the frequency of neonatal complications. CONCLUSION: Amniotic fluid volume does not greatly affect neonatal outcome in normal diamniotic twin pregnancies.

Amniotic fluid volume in normal singleton pregnancies.

OBJECTIVE: To evaluate the amniotic fluid (AF) volume in normal singleton pregnancies from 15 to 40 weeks. METHODS: This prospective study evaluated the AF volume in singleton pregnancies undergoing amniocentesis for genetic assessment of fetal karyotype, preterm labor, or fetal lung maturity. Amniotic fluid volume was determined using a dye dilution technique. To assess the relationship between AF volume and estimated gestational age, a nonlinear regression model was applied. RESULTS: One hundred forty-four normal singleton pregnancies had AF volume evaluated. There was wide variability in the measured AF volumes with a significant (P < .01) increase in AF volume as a function of gestational age. Growth curve modeling estimated that AF volume continued to increase until 40 weeks' gestation. Analyses of the observed AF volume indicated that AF volume nearly doubled after 30 weeks' gestation. CONCLUSION: In contrast to other reports indicating that maximal AF volume in singleton gestations is expected early in the third trimester, we observed the attainment of maximal AF volume near term.

Survival of carcinoma of the prostate patients less than 55 years old compared to older patient groups.

Both incidence and death rate from cancer of prostate are rising. Prostate cancer is the most common malignancy in man and second most common cause of death in men. Lung cancer is the leading cause of death in men. Carcinoma of prostate is generally a disease of older men. Carcinoma of prostate can also occur in the middle-aged men. This study was performed to find whether the middle-aged men survived longer than older men when both groups of patients were compared according to equivalent stage of the disease. In this series, survival is slightly better in younger age groups when patients of all stages are pooled together. Due to small number of patients in younger age groups, survival difference cannot be calculated for each stage of the disease.

The effect of levenogesterol (Norplant) contraception on coagulation as measured by antithrombin-III levels.

PURPOSE: To determine the effect of contraception given immediately postpartum on coagulation as measured by antithrombin III. STUDY DESIGN: In this prospective study, parturients (n = 85) self selected three means of postpartum contraception: levenorgesterol implants, oral contraceptives, or a barrier method. RESULTS: Baseline coagulation was assessed by antithrombin-III levels in each of the 85 women within 48 hours of delivery (100.35 +/- 1.61%) and at one (109.1 +/- 1.89%) and six (105.51 +/- 1.71%) weeks postpartum. There was a rise in antithrombin-III after delivery but there were no significant differences between the groups. CONCLUSION: The levenorgesterol implant system did not cause a decrease in antithrombin-III in normal parturients.

PIP: The effect of postpartum Norplant implant use on coagulation factors was investigated in a prospective study conducted in Mississippi, US. 85 postpartum women were given a choice of 3 contraceptive methods: levonorgestrel implants (n = 25), oral contraceptives (n = 38), or a barrier method (n = 22). Antithrombin-III (AT-III) levels were measured on the day of discharge from the hospital after delivery, 7 days after delivery, and 6 weeks after delivery. There was no significant difference between groups in the initial AT-III level (mean, 100.35 +or- 1.61%). At the end of the first postpartum week, AT-III levels rose significantly to 109.1 +or- 1.89%, but again, there were no significant differences according to contraceptive method. By the 6-week follow-up, AT-III levels had stabilized at a mean of 105.51 +or- 1.71%, with no significant between-group differences. AT-III levels in pill users declined more markedly between the first and sixth postpartum weeks than those in the 2 other groups. These findings indicate that subdermal implant use does not affect coagulation, and these devices can be inserted safely during the postpartum period.

Durability of venous valve reconstruction techniques for "primary" and postthrombotic reflux.

PURPOSE: The durability of the variety of valve reconstruction techniques in "primary" reflux and postthrombotic reflux was studied. METHODS: A total of 423 valve repairs in 235 patients with a follow-up period ranging from 1 to 12 years were analyzed. End points for assessment consisted of ulcer recurrence and Doppler competence in serial duplex examination. Multivariate analysis with Cox proportional hazards model was used. RESULTS: Ulcer-free survival curves were similar for "primary" and postthrombotic reflux. No significant difference in ulcer recurrence was seen regardless of the technique used. Different results were obtained when valve competence instead of ulcer recurrence was used for assessment of durability. Reconstructions in "primary" reflux were more durable than those in postthrombotic reflux. Durability differences were also noted among different techniques. A cohort of posterior tibial repairs proved extraordinarily durable (0 failures in 23 repairs). CONCLUSION: Valve reconstruction in postthrombotic reflux can yield clinical results similar to those in "primary" reflux. Although any of the several described techniques can produce similar clinical results, Doppler competence suggests the following order for choice of procedures: (1) internal valvuloplasty, (2) prosthetic sleeve in situ, (3) external valvuloplasty, and (4) axillary vein transfer.

Infectious morbidity, operative blood loss, and length of the operative procedure after cesarean delivery by method of placental removal and site of uterine repair.

OBJECTIVE: This study was done to determine the impact of the method of placental removal and the site of uterine repair on postcesarean infectious morbidity rates in women receiving prophylactic antibiotics at cesarean delivery. STUDY DESIGN: This prospective study included 284 women who underwent cesarean delivery and who were randomly assigned to four groups based on the method of placental removal and the site of uterine repair: group 1, spontaneous placental removal and in situ uterine repair; group 2, spontaneous placental removal and exteriorized uterine repair; group 3, manual placental removal and in situ uterine repair; and group 4, manual placental removal with exteriorized uterine repair. Exclusion criteria were repeat cesarean deliveries without labor, active infection at the time of cesarean delivery, and patient refusal to participate. RESULTS: There was no significant difference among the groups in maternal age, race, parity, weight, the length of time from rupture of membranes (ROM) or the number of vaginal examinations from ROM to cesarean delivery, or preoperative hematocrit. Intraoperatively, the type of uterine incision, anesthesia administered, incidence of meconium-stained amniotic fluid, Apgar scores, and cord gases were similar between groups. The incidence of postcesarean endometritis was greater in group 4 (32 [45 percent] of 71, p = 0.003) compared with group 1 (17 [24 percent] of 71), group 2 (12 [30 percent] of 71); and group 3 (13 [18 percent] of 71). CONCLUSIONS: Manual placental removal and exteriorization of the uterus for repair of the surgical incision increases the infectious morbidity rate in women receiving prophylactic antibiotics at the time of cesarean delivery and increases the length of hospitalization.

Factors adversely affecting pregnancy outcome in the military.

This prospective study was undertaken to identify the significant risk factors associated with adverse pregnancy outcome in active-duty women. The deliveries of 300 consecutive pregnancies of active-duty women were assessed for maternal-fetal outcome. The risk factors evaluated were: marital status, parity, race, smoking and alcohol consumption while pregnant, maternal weight gain during pregnancy, maternal height, and educational level. Two-thirds of these women were junior enlisted personnel (rank E-4 or below) and worked under demanding job conditions over which they had little control. Increased age as a risk factor was associated with a significant increase in pregnancy-associated complications of cesarean birth, operative vaginal delivery, pregnancy-induced hypertension, preterm labor, maternal transport for fetal indications, intrauterine growth restriction, intrauterine fetal death, postpartum hemorrhage, placenta previa, and 5-minute Apgar scores < 7 (p = 0.039). In gravidas more than 65 inches in height with a weight gain more than 42 pounds, there was a significant increase in the complications of pregnancy (p = 0.022). Interactions of these risk factors yielded a significant age (p = 0.025), maternal height (p = 0.007), and height times weight gain interaction (p = 0.006) association with pregnancy complications. The risk factors of advancing maternal age and tall stature with a maternal weight gain of more than 42 pounds are associated with increased pregnancy complications of active-duty women.

Tumor necrosis factor alpha gene expression in human peritoneal macrophages is suppressed by extra-abdominal trauma.

BACKGROUND: Trauma is believed to activate immunocytes but paradoxically also increases the risk of intraperitoneal infection. OBJECTIVE: To investigate these events by evaluating changes in the cytokine control networks of human peritoneal macrophages (PM phi) early after trauma. DESIGN: Case-control study comparing cytokine messenger RNA (mRNA) expression by PM phi from patients with extra-abdominal trauma with that of both peripheral blood mononuclear cells (PBM) and PM phi obtained from healthy individuals. SETTING: Level I trauma center and basic science laboratory in a university hospital center. PATIENTS: Six patients with polytrauma (Injury Severity Score, > or = 15) with clinically negative diagnostic peritoneal lavages performed on routine indications at admission to the emergency department and six healthy age- and sex-matched individuals undergoing inguinal herniorrhaphy under local anesthesia. INTERVENTIONS: Peritoneal macrophages were isolated from diagnostic peritoneal lavages in trauma patients. Identical lavages were performed through the hernia sac in the control group. MEASUREMENTS: Cellular RNA was assayed for tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta, IL-6, and IL-10 message by semiquantitative reverse-transcription polymerase chain reaction. RESULTS: Normal PM phi expressed high levels of TNF-alpha mRNA relative to PBM, but expression of the other proinflammatory cytokines was equivalent to that of PBM. Peritoneal macrophage expression of TNF-alpha mRNA was markedly (64-fold) decreased after trauma (P < .001), when PBM expression of IL-10 mRNA was increased (P = .03). CONCLUSIONS: Human PM phi constitutively show high levels of TNF-alpha message expression, and this is down-regulated by polytrauma. This might constitute a functionally "primed" state. If so, TNF-alpha down-regulation might contribute to functional PM phi suppression after systemic injury.

Human peripheral mononuclear cells do not show proinflammatory patterns of cytokine transcription in early trauma: a preliminary report.

Injury has been hypothesized to cause inflammation through systemic release of lipopolysaccharide and pro-inflammatory cytokines, but this has proved difficult to demonstrate in humans. We looked for evidence of an inflammatory pattern of cytokine gene expression by peripheral blood mononuclear cells (PBM) in six polytraumatized patients (ISS = 25 +/- 8) upon ER admission, and in six matched healthy controls. PBM tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-4, IL-6, IL-10, and interferon (IFN)-gamma message was assessed by semi-quantitative reverse-transcription polymerase chain reaction. No increase in expression of any of the pro-inflammatory cytokines (tumor necrosis factor-alpha, IL-1 beta, or IL-6) was found after trauma, and IFN-gamma tended to decrease. Of the immunosuppressive cytokines, IL-10 expression increased 5-fold (p < .05) but no change in IL-4 was discerned. This pattern is fundamentally different from the cytokine expression patterns expected with sepsis or exposure to lipopolysaccharide. These findings are inconsistent with the occurrence of systemic endotoxemia and subsequent global immunocyte activation early after trauma.

Single daily dose of methimazole compared to every 8 hours propylthiouracil in the treatment of hyperthyroidism.

This study to compare single-dose and multiple-dose antithyroid therapy was prompted by a perceived lack of compliance in our University Medical Clinics by those patients using multidose regimens. Twenty-two hyperthyroid patients were randomly assigned to two therapy groups. Twelve received methimazole (Tapazole) 30 mg once daily in the morning; 10 received propylthiouracil 100 mg every 8 hours. Patients were seen every 4 weeks for 3 months and assessed clinically, as well as having the appropriate thyroid tests done. Univariate analysis revealed no difference in the two groups at baseline. Posttreatment assessment revealed the once-a-day methimazole therapy to be just as effective as propylthiouracil in improving thyroid indices and clinical markers. Compliance with methimazole was 83.3% compared to 53.3% with propylthiouracil. In conclusion, once-a-day methimazole was just as effective as propylthiouracil every 8 hours in this population. Compliance was also improved with the once-a-day therapy.

Does level of ligation influence results in a murine biliary obstruction model?

BACKGROUND: Despite advances in perioperative management, patients with extrahepatic biliary obstruction still experience a high rate of complications and death after surgery. The rat is commonly used as an experimental animal for research in obstructive jaundice. Ligation of the rat bile duct high in the liver hilum is assumed to produce a more severe model of biliary obstruction than low ligation. The differences are attributed to the ability of the rat bile duct to dilate. Differences in level of ligation may, thus, explain some discrepancies between studies. MATERIALS AND METHODS: To test this hypothesis, female Lewis rats underwent high ligation (HL), low ligation (LL), and sham celiotomy. Colloidal carbon clearance, bilirubin, total serum bile acids, and hematocrit were measured 12 days later. Liver and spleen weight, presence or absence of ascites, infection, and adequacy of ligation were noted and the liver was processed for routine histology and electron microscopy. RESULTS: Although bilirubin levels were higher after HL than after LL, liver and spleen weight, total serum bile salts, and phagocytic constants K and alpha were not different between these two groups. Gross, histologic, and ultrastructural appearance did not differ between HL and LL groups. CONCLUSION: High ligation causes greater hyperbilirubinemia than low ligation, but does not alter other parameters including phagocytic constants. The present study does not confirm the hypothesis that HL creates a more severe model than LL; therefore, it is unlikely that differences in level of ligation explain variability in results between studies.

Acute tocolysis for suspected intrapartum fetal distress: maternal effects of terbutaline versus magnesium sulfate.

This study was undertaken to determine the maternal hemodynamic impact of terbutaline versus magnesium sulfate in the acute treatment of fetal distress prior to cesarean delivery. Forty-six women were prospectively randomized to receive 0.25 mg subcutaneous terbutaline or 4.0 g intravenous magnesium sulfate for in utero fetal resuscitation before cesarean delivery. There were no significant differences between groups in baseline mean arterial pressure, arterial pressure before and after induction of anesthesia, maternal heart rate, maternal oxygen saturation, estimated blood loss, and pre- and postoperative hematocrits. Magnesium sulfate-treated women received significantly more intraoperative intravenous fluids (2365 +/- 877 ml) than the terbutaline group (1624 +/- 564 ml; P < 0.001). However, mean urine output was significantly greater in the terbutaline group (88 +/- 42 ml/h) than in those treated with magnesium sulfate (61 +/- 26 ml/h; P < 0.03). Terbutaline, the superior agent for acute tocolysis, is not associated with an increase in maternal cardiovascular side effects during anesthesia.