Stabilization of molten salt materials using metal chlorides for solar thermal storage.

The effect of a variety of metal-chlorides additions on the melting behavior and thermal stability of commercially available salts was investigated. Ternary salts comprised of KNO3, NaNO2, and NaNO3 were produced with additions of a variety of chlorides (KCl, LiCl, CaCl2, ZnCl2, NaCl and MgCl2). Thermogravimetric analysis and weight loss experiments showed that the quaternary salt containing a 5 wt% addition of LiCl and KCl led to an increase in short term thermal stability compared to the ternary control salts. These additions allowed the salts to remain stable up to a temperature of 630 °C. Long term weight loss experiments showed an upper stability increase of 50 °C. A 5 wt% LiCl addition resulted in a weight loss of only 25% after 30 hours in comparison to a 61% loss for control ternary salts. Calorimetry showed that LiCl additions allow partial melting at 80 °C, in comparison to the 142 °C of ternary salts. This drop in melting point, combined with increased stability, provided a molten working range increase of almost 100 °C in total, in comparison to the control ternary salts. XRD analysis showed the oxidation effect of decomposing salts and the additional phase created with LiCl additions to allow melting point changes to occur.

Thrombotic markers in metabolic syndrome subjects exposed to diesel exhaust.

Traffic-derived particulate matter (PM) is associated with cardiovascular morbidity and mortality, but the mechanism of this association is unclear. Prothrombotic processes have been linked to PM in epidemiological and animal models, but have not been consistently implicated in controlled human models. Diesel exhaust (DE) is a major contributor to PM. We conducted a controlled human exposure of DE in subjects with metabolic syndrome. The study objective was to evaluate DE exposure effects on prothrombotic markers in a population vulnerable to cardiovascular disease. A randomized, crossover, double-blinded design was used: 16 subjects with metabolic syndrome exposed on 3 different days (> or = 2 wk washout) to DE at 0 (filtered air, FA), 100 microg PM(2.5)/m(3) (DE(100)) and 200 mug PM(2.5)/m(3) (DE(200)). We assessed DE-associated changes in D-dimer, von Willebrand factor (VWF), and plasmin activator inhibitor-1 (PAI-1) at 3, 7, and 22 h after exposure initiation. A DE(200)-attributable decrease (1.17-fold; CI 1.04 to 1.34) in VWF was noted at 7 h. Significant changes did not occur in other primary endpoints. As previously noted with healthy subjects, strong diurnal patterns in PAI-1 were observed. Thus, in a novel study, we were unable to demonstrate a prothrombotic effect of moderate-dose diesel exhaust exposure in a population at risk for cardiovascular disease.

Association between short term exposure to fine particulate matter and heart rate variability in older subjects with and without heart disease.

BACKGROUND: Short term increases in exposure to particulate matter (PM) air pollution are associated with increased cardiovascular morbidity and mortality. The mechanism behind this effect is unclear, although changes in autonomic control have been observed. It was hypothesised that increases in fine PM measured at the subjects' home in the preceding hour would be associated with decreased high frequency heart rate variability (HF-HRV) in individuals with pre-existing cardiac disease. METHODS: Two hundred and eighty five daily 20 minute measures of HRV (including a paced breathing protocol) were made in the homes of 34 elderly individuals with (n = 21) and without (n = 13) cardiovascular disease (CVD) over a 10 day period in Seattle between February 2000 and March 2002. Fine PM was continuously measured by nephelometry at the individuals' homes. RESULTS: The median age of the study population was 77 years (range 57-87) and 44% were male. Models that adjusted for health status, relative humidity, temperature, mean heart rate, and medication use did not find a significant association between a 10 microg/m3 increase in 1 hour mean outdoor PM2.5 before the HRV measurement and a change in HF-HRV power in individuals with CVD (3% increase in median HF-HRV (95% CI -19 to 32)) or without CVD (5% decrease in median HF-HRV (95% CI -34 to 36)). Similarly, no association was evident using 4 hour and 24 hour mean outdoor PM2.5 exposures before the HRV measurement. CONCLUSION: No association was found between increased residence levels of fine PM and frequency domain measures of HRV in elderly individuals.

Antipneumolysin antibody titers in HIV-seropositive injection drug users before and after pneumococcal bacteremia.

Lower baseline antipneumolysin antibody (alpha-PLY) levels have been found in populations with a higher incidence of pneumococcal infections. To determine whether predisease alpha-PLY titer is associated with invasive pneumococcal disease in HIV-seropositive injection drug users (IDU), we utilized a prospective cohort of IDU in Baltimore to compare alpha-PLY titers before bacteremia in 28 HIV- seropositive IDU cases with alpha-PLY titers in 56 matched (CD4 and seroconversion date) HIV-seropositive IDU control subjects and 28 matched (calendar time) HIV-seronegative IDU control subjects remaining free of pneumococcal disease. We also compared the postinfection fold-rise of alpha-PLY titers in cases relative to the change in alpha-PLY titers in control subjects during the same interval; alpha-PLY titers were measured using quantitative ELISA, and functional activity was assessed using antihemolysin assays. Predisease alpha-PLY titer did not differ between cases (66 units) and HIV-seropositive control subjects (70 units, p = 0.56) or HIV-seronegative control subjects (80 units, p = 0.10). There was a significant difference in fold-rise of alpha-PLY titers postdisease between cases (1.18) and HIV-seronegative control subjects (0.76), p = 0.03. Baseline alpha-PLY titers do not differ significantly between HIV-seropositive IDU who develop pneumococcal bacteremia from HIV-seropositive and HIV-seronegative IDU control subjects remaining free of severe pneumococcal disease.

Effect of antiretroviral therapy on the incidence of bacterial pneumonia in patients with advanced HIV infection.

To determine the relationship of combination antiretroviral therapy and bacterial pneumonia, we assessed incidence of and risk factors for bacterial pneumonia in 1,898 human immunodeficiency virus (HIV)-infected patients with CD4 cell counts < 200/mm(3) followed in the Johns Hopkins HIV clinic between 1993 and 1998. A total of 352 episodes of bacterial pneumonia occurred during 2,310 patient-years of follow-up. Incidence of bacterial pneumonia decreased from 22.7 episodes/100 person-years (py) in the first half of 1993 to 12.3 episodes/100 py in the first half of 1996, reaching a nadir of 9.1 episodes/100 py in the second half of 1997 (p < 0.05). The use of protease inhibitor-containing regimens was associated with a decreased risk of bacterial pneumonia (risk ratio [RR] 0.55, 95% CI 0.31 to 0.94). Lower CD4 cell counts (RR 2.22, 95% CI 1.54 to 3.18), injection drug use as HIV transmission category (RR2.0, 95% CI 1.43 to 2.76), and prior Pneumocystis carinii pneumonia (RR 3.88, 95% CI 1.65 to 9.16) were also significantly associated with bacterial pneumonia. Trimethoprim-sulfamethoxazole and macrolide use were not significantly associated with risk of bacterial pneumonia. There has been a dramatic decline in the incidence of bacterial pneumonia resulting from the use of combination antiretroviral therapy containing protease inhibitors.

Effects of UV-B radiation on photosynthesis and growth of terrestrial plants.

The photosynthetic apparatus of some plant species appears to be well-protected from direct damage from UV-B radiation. Leaf optical properties of these species apparently minimizes exposure of sensitive targets to UV-B radiation. However, damage by UV-B radiation to Photosystem II and Rubisco has also been reported. Secondary effects of this damage may include reductions in photosynthetic capacity, RuBP regeneration and quantum yield. Furthermore, UV-B radiation may decrease the penetration of PAR, reduce photosynthetic and accessory pigments, impair stomatal function and alter canopy morphology, and thus indirectly retard photosynthetic carbon assimilation. Subsequently, UV-B radiation may limit productivity in many plant species. In addition to variability in sensitivity to UV-B radiation, the effects of UV-B radiation are further confounded by other environmental factors such as CO2, temperature, light and water or nutrient availability. Therefore, we need a better understanding of the mechanisms of tolerance to UV-B radiation and of the interaction between UV-B and other environmental factors in order to adequately assess the probable consequences of a change in solar radiation.

The effects of ultraviolet-B radiation on photosynthesis of different aged needles in field-grown loblolly pine.

We examined the effect of supplemental UV-B radiation (290-320 nm) on photosynthetic characteristics of different aged needles of 3-year-old, field-grown loblolly pine (Pinus taeda L.). Needles in four age classes were examined: I, most recently fully expanded, year 3; II, first flush, year 3; III, final flush, year 2; and IV, oldest needles still present, year 2. Enhanced UV-B radiation caused a statistically significant decrease (6%) in the ratio of variable to maximum fluorescence (F(v)/F(m)) following dark adaptation only in needles from the youngest age class, suggesting transient damage to photosynthesis. However, no effects of enhanced UV-B radiation on other instantaneous measures of photosynthesis, including maximum photosynthesis, apparent quantum yield and dark respiration, were seen for needles of any age. Foliar nitrogen concentration was unaffected by UV-B treatment. However, the (13)C/(12)C carbon isotope ratios (delta(13)C-a time integrated measure of photosynthetic function) of needles in age classes II and IV were 3% (P < 0.01) and 2% (P < 0.05) more negative, respectively, in treated plants than in control plants. Exposure to enhanced UV-B radiation caused a 20% decrease in total biomass and a 4% (P < 0.05), 25% (P < 0.01), and 9% (P < 0.01) decrease in needle length of needles in age classes I, II, and IV, respectively. The observed decreases in delta(13)C, and F(v)/F(m) of the needles in the youngest needle age class suggest subtle damage to photosynthesis, although overall growth reductions were probably a result of decreased total leaf surface rather than decreased photosynthetic capacity. Needles of age class IV had lower light- and CO(2)-saturated maximum photosynthetic rates (39%), lower dark respiration (34%), lower light saturation points (37%), lower foliar nitrogen concentration (28%), and lower delta(13)C (14%) values than needles of age class I. Apparent quantum yield and F(v)/F(m) did not change with needle age. The observed changes in photosynthesis and foliage chemical composition with needle age are consistent with previous studies of coniferous trees and may represent adaptations of older needles to shaded conditions within the canopy.

Contrast enema diagnosis of necrotizing enterocolitis.

Contrast enema was performed in a select group of 126 neonates with ambiguous diagnosis of necrotizing enterocolitis (NEC). Enema findings were compared with that on plain abdominal radiographs (AXR) and the clinical outcome. Thirty-one of the 34 patients with a discharge diagnosis of NEC were interpreted to have a positive contrast enema, and 91 of the 92 patients without a discharge diagnosis of NEC were interpreted to have a negative contrast enema. The AXR was interpreted as positive in 57 patients and as negative or indeterminate in 69. Not a single case of perforation was produced. Judicious use of contrast enema can improve specificity of diagnosis in cases with discordant clinical and plain radiographic findings.

Self-compression plates for orbital rim fractures.

The development and principles of self-compression plating, as well as a series of patients treated with this technique, are described. The use of such plates has specific advantages over other techniques for disorders encountered by the oculoplastic surgeon. The indications for plating were displaced trimalar fracture, displaced trimalar fracture with orbital rim fragment, and comminuted orbital rim fracture. Results were good; no complications have been observed to date. Comparison of compression plating to other methods for repair of orbital fractures is made. Self-compression plating with Vitallium plates is an effective modality for the treatment of a broad spectrum of patients with orbital rim fractures.

Interaction of Elevated Ultraviolet-B Radiation and CO(2) on Productivity and Photosynthetic Characteristics in Wheat, Rice, and Soybean.

Wheat (Triticum aestivum L. cv Bannock), rice (Oryza sativa L. cv IR-36), and soybean (Glycine max [L.] Merr cv Essex) were grown in a factorial greenhouse experiment to determine if CO(2)-induced increases in photosynthesis, biomass, and yield are modified by increases in ultraviolet (UV)-B radiation corresponding to stratospheric ozone depletion. The experimental conditions simulated were: (a) an increase in CO(2) concentration from 350 to 650 microliters per liter; (b) an increase in UV-B radiation corresponding to a 10% ozone depletion at the equator; and (c) a and b in combination. Seed yield and total biomass increased significantly with elevated CO(2) in all three species when compared to the control. However, with concurrent increases in UV-B and CO(2), no increase in either seed yield (wheat and rice) or total biomass (rice) was observed with respect to the control. In contrast, CO(2)-induced increases in seed yield and total plant biomass were maintained or increased in soybean within the elevated CO(2), UV-B environment. Whole leaf gas exchange indicated a significant increase in photosynthesis, apparent quantum efficiency (AQE) and water-use-efficiency (WUE) with elevated CO(2) in all 3 species. Including elevated UV-B radiation with high CO(2) eliminated the effect of high CO(2) on photosynthesis and WUE in rice and the increase in AQE associated with high CO(2) in all species. Elevated CO(2) did not change the apparent carboxylation efficiency (ACE) in the three species although the combination of elevated CO(2) and UV-B reduced ACE in wheat and rice. The results of this experiment illustrate that increased UV-B radiation may modify CO(2)-induced increases in biomass, seed yield and photosynthetic parameters and suggest that available data may not adequately characterize the potential effect of future, simultaneous changes in CO(2) concentration and UV-B radiation.

Field Study of the Interaction between Solar Ultraviolet-B Radiation and Drought on Photosynthesis and Growth in Soybean.

Soybean, Glycine max (L.) Merr. cv Essex, plants were grown in the field in a 2 x 2 factorial design, under ambient and supplemental levels of ultraviolet-B (UV-B) radiation (supplemental daily dose of 5.1 effective kilojoules per square meter) and were either well-watered or subjected to drought. Soil water potentials were reduced to -2.0 megapascals by the exclusion of natural precipitation in the drought plots and were maintained at approximately -0.5 megapascal by supplemental irrigation in well-watered plots. Plant growth and gas exchange characteristics were affected under both drought and supplemental UV-B radiation. Whole-leaf gas exchange analysis indicated that stomatal limitations on photosynthesis were only significantly affected by the combination of UV-B radiation and drought but substrate (ribulose bisphosphate) regeneration limitations were observed under either stress. The combined effect of both drought and UV-B radiation on photosynthetic gas exchange was a reduction in apparent quantum efficiency and the rapid appearance of biochemical limitations to photosynthesis concomitant with reduced diffusional limitations. However, the combination of stresses did not result in additive effects on total plant growth or seed yield compared to reductions under either stress independently.

Pretarsal fixation of gold weights in facial nerve palsy.

Implantation of a gold weight in the pretarsal space was performed on 17 patients with poor eyelid closure secondary to facial nerve weakness. Successful results were obtained in 14 (82%) of 17 patients. Postmortem histopathology of such a case demonstrated firm fibrous encapsulation of the weight. Although some authors advocate fixation of lid weights to the orbital septum, fixation in the pretarsal space is preferred for the following reasons: (a) "cheesewiring" is less likely to occur, (b) a limited levator recession may be more easily performed, (c) greater mechanical benefits are obtained, and (d) the potential for inferior migration is less.

Eyelid anaphylactic reaction to atracurium with general anesthesia.

Atracurium is a relatively new neuromuscular blocking anesthetic with known histamine release effects which has become popular in ophthalmic anesthesia. This report describes the IV use of Atracurium causing an anaphylactic reaction manifested by localized edema of all four eyelids, conjunctival chemosis and mild laryngeal edema requiring scheduled ptosis and strabismus surgery to be cancelled.

The pathogenesis of retinal detachment with morning glory disc and optic pit.

A child with nonrhegmatogenous retinal detachment associated with morning glory disc underwent first a vitrectomy and then, some months later, an optic nerve sheath fenestration. The latter procedure led to retinal reattachment. It also produced a biopsy specimen that confirmed the perineural herniation of poorly differentiated retinal tissue in this condition, similar to that in congenital pit of the optic nerve. It demonstrated continuity of the vitreous cavity with the perineural space, both histologically and by the fact that gas injected through the pars plana into the vitreous cavity bubbled out the window in the optic nerve sheath. The authors suggest that morning glory disc and optic pit share similar anatomic features, differing more in degree than in kind, and that the porous nature of the poorly differentiated tissue herniated around the optic nerve into the subarachnoid space in these conditions makes several sources of subretinal fluid possible.

Cryosurgery in ophthalmic practice.

Cutaneous cryosurgery is useful in an ophthalmic practice in the treatment of basal cell carcinoma, trichiasis, and other benign cutaneous disorders. Indications and techniques for using liquid nitrogen and nitrous oxide instruments are discussed.