Effect of thermal dissipation by adding graphene materials to surface coating of LED lighting module.

The effect of thermal dissipation by adding graphene nano-platelets to two different commercially available thermal dissipation coatings (ceramic coating and powder coating) was studied. Steady state temperatures of each points of LED modules was monitored in a closed system, with an integral photo detection sphere where there is no external air flow. Having eliminated the contributions of thermal conduction and air flow convection, the module with a conventional heat dissipation coatings showed 8-16% enhancement of thermal dissipation compared to that of non-coated LED module. The addition of graphene is shown to have about 3% additional enhancement. By analyzing thermal resistance of each component of the LED module, the improved thermal conductivity of the graphene added coatings contributes to the enhancement of slight improvement with heat dissipation.

Electrochemical characterization of nano-sized Pd-based catalysts as cathode materials in direct methanol fuel cells.

To improve the catalytic activity of palladium (Pd) as a cathode catalyst in direct methanol fuel cells (DMFCs), we prepared palladium-titanium oxide (Pd-TiO2) catalysts which the Pd and TiO2 nanoparticles were simultaneously impregnated on carbon. We selected Pd and TiO2 as catalytic materials because of their electrochemical stability in acid solution. The crystal structure and the loading amount of Pd and TiO2 on carbon were characterized by X-ray diffraction (XRD) and energy dispersive X-ray microanalysis (EDX). The electrochemical characterization of Pd-TiO2/C catalysts for the oxygen reduction reaction was carried out in half and single cell systems. The catalytic activities of the Pd-TiO2 catalysts were strongly influenced by the TiO2 content. In the single cell test, the Pd-TiO2 catalysts showed very comparable performance to the Pt catalyst.

Electrochemical characterization of Pt-Ru-Pd catalysts for methanol oxidation reaction in direct methanol fuel cells.

PtRuPd nanoparticles on carbon black were prepared and characterized as electrocatalysts for methanol oxidation reaction in direct methanol fuel cells. Nano-sized Pd (2-4 nm) particles were deposited on Pt/C and PtRu/C (commercial products) by a simple chemical reduction process. The structural and physical information of the PtRuPd/C were confirmed by TEM and XRD, and their electrocatalytic activities were measured by cyclic voltammetry and linear sweep voltammetry. The catalysts containing Pd showed higher electrocatalytic activity for methanol oxidation reaction than the other catalysts. This might be attributed to an increase in the electrochemical surface area of Pt, which is caused by the addition of Pd; this results in increased catalyst utilization.

TCDD-up-regulation of IGFBP-6 and IL-5R alpha subunit genes in vivo and in vitro.

Although the potent environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been well known for its immunosuppressive activity, the mechanisms of its action have been difficult to elucidate. This is partly due to its inability to exert its effects in vitro. To further elucidate the underlying mechanisms of TCDD effects, we screened for genes that are regulated by the in vivo TCDD treatment of mice that are challenged with allogeneic tumor cells. RNA, collected from lymphoid organs including the thymus, draining lymph nodes, and bone marrow, was reverse-transcribed to cDNA and hybridized to DNA arrays that consisted of 588 genes (ClonTech, USA). The expression of the NF-kappaB p65, c-jun, and p27(Kip1) genes was increased by the TCDD treatment, as previously reported. In addition, we found that the expression of several genes, which were not reported as regulated by TCDD, were modulated by TCDD. Some genes, including insulin-like growth factor-binding protein-6 (IGFBP-6) and IL-5R alpha, were upregulated; while other genes, including CD14, were down-regulated. The expression of the IGFBP-6 and IL-5R alpha subunit genes by TCDD in the thymus was confirmed by RT-PCR and Western blot analyses. Furthermore, TCDD effects on the expression of the IGFBP-6 gene was also observed with EL4 mouse thymoma cells. This suggests that IGFBP-6 may be involved in thymic atrophy, and EL4 cells may be used as an in vitro model for studying molecular mechanisms of thymic atrophy.

Mucociliary activity and ultrastructural abnormalities of regenerated sinus mucosa in rabbits.

The purpose of this study was to observe histologic findings in the regenerated maxillary sinus mucosa and restoration of ciliary activity by measuring the speed of mucociliary transport after complete surgical removal of the maxillary sinus mucosa. The maxillary sinuses of 32 rabbits were opened anteriorly and one side of the sinus mucosa of each animal was completely removed. In 16 animals, the natural ostia were widened, and, in another 16 animals, the natural ostia were left undisturbed. The contralateral, sham-operated sinus was used as a control for each animal. The animals of each group were reanesthetized and the maxillary sinuses were reopened at planned intervals. The speed of mucociliary transport toward the maxillary ostium, determined by India ink particle movement, was reduced to 6.4 mm/min, whereas it was 10.8 mm/min in the control side. Beating cilia were observed in 16% by dark-field microscopy, in contrast to 66% in the control sinus. Pseudostratified columnar epithelia without cilia were present in 12%, with the remaining consisting of pseudostratified ciliated columnar epithelia (88%). Light microscopic examination showed increase in submucosal fibrotic proliferation, decrease in submucosal glands, and infiltration of inflammatory cells. Under transmission electron microscopy, abnormal cilia such as compound cilia or edematous cilia were frequently found in the regenerated specimens. These observations suggest that mucociliary clearance of the regenerated sinus mucosa may be significantly diminished compared with that of the original mucosa.

Serous retinal detachment in a patient with rhino-orbital mucormycosis.

BACKGROUND: Rhino-orbital mucormycosis is a difficult disease to treat. We report one case of rhino-orbital mucormycosis, complicated by serous retinal detachment, that responded to aggressive treatment. CASE: A 38-year-old man with diabetic ketoacidosis was referred to the emergency department of our hospital with fever, proptotic right eye, and complaint of lethargy. OBSERVATIONS: Fundus examination showed serous retinal detachment and focal lesions of retinitis with exudate at the inferior portion coincident with the position of opacification in the orbit on MRI. Fluorescein angiography showed pooling of dye in the detached retina and leakage from focal lesions of retinitis. We thoroughly removed the large necrotic materials in the orbit and sinus through the lower conjunctiva without enucleation or exenteration. Microscopic examination and culture of the necrotic materials that were removed from the orbit proved that the patient had mucormycosis. The serous retinal detachment improved 10 days after orbital debridement combined with intravenous and local (intraorbital) amphotericin B treatment. Visual acuity recovered to 20/50. CONCLUSION: We propose that inflammation of the sclera in close contact with necrotic fungi materials may cause serous retinal detachment.

Efficacy of intravitreal hemocoagulase for control of bleeding in rabbit experimental model of vitrectomy.

Hemorrhage during vitrectomy for diabetic retinopathy or in the recently traumatized eye can complicate the surgical procedures and might cause termination and failure of vitrectomy in some cases. The effect of the hemocoagulase, Botropase, on the hemostasis of intraocular bleeding was evaluated in a rabbit model by cutting central retinal vessels in the medullary ray. Addition of the hemocoagulase (1 NIH unit/100 ml) to BSS Plus significantly reduced bleeding time. Immediately after vitrectomy with the use of this hemocoagulase, the average of the maximum amplitudes of the b-wave in electroretinography was normal, although the sensitivity of the electroretinogram was reduced by 0.1 log unit in the experimental eyes which were infused with hemocoagulase solution. The sensitivity showed no significant difference after the second postoperative day. The experimental eyes showed no abnormal findings histologically. Infusate containing Botropase appeared to be a useful adjunct for the control of intraocular bleeding during vitreous surgery.

Leaching behavior and characteristics of glass components and surrogate nuclides in radioactive vitrified waste forms.

Several vitrified waste forms were fabricated and characterized, which contain simulated radioactive waste incineration ash, and a long-term leaching test was conducted by an ISO method for 820 days to assess the chemical durability of vitrified waste forms. Two semi-empirical mechanism models were applied to find out the dominant leaching mechanism of glass elements. For glass elements, dissolution associated with diffusion was the dominant leaching mechanism and leaching characteristics also depend upon solubilities of components. A type of prediction model was applied to observe the long-term leaching behavior of major glass elements and surrogates. Diffusion coefficients and dissolution rate constants, the main parameters in the long-term prediction model, were obtained for glass elements and surrogate nuclides using experimental data for short and long-term periods. The model could be used to predict long-term behavior of such elements to observe and assess the stability of vitrified waste forms.

Degradation of phagosomes and diurnal changes of lysosomes in rabbit retinal pigment epithelium.

Diurnal changes of lysosomes including ultrastructural changes of phagosomes and acid phosphatase reactions in phagosomes, as well as diurnal biochemical changes in cathepsin D activity, were studied in the retinal pigment epithelium (RPE) of the rabbit. The rabbit was maintained on a natural light-dark cycle over seven days in fall and was sacrificed at various times during the day and night. The number of lysosomes or phagosomes in the RPE was the highest at 1.5 hours after exposure to sunlight (8:00 AM), and thereafter decreased with time. Three types of phagosomes were observed and acid phosphatase reactions were different in each type of phagosome; the fresh phagosomes were negative or positive, lamellar bodies positive, and dense bodies partially positive. The biochemical activity of cathepsin D was the highest at 8:00 AM, and this was consistent with the time of peak in phagocytic activity in the RPE. This report shows that phagocytic activity in the RPE occurred in the early stage after exposure to sunlight, and that fresh phagosomes were sequentially degraded to lamellar or dense bodies. Cathepsin D activity also increased, and this was consistent with the phagocytic activity in the RPE.

Long-term visual recovery after scleral buckling procedure of rhegmatogenous retinal detachment involving the macula.

The long-term visual recovery after a scleral buckling procedure for rhegmatogenous retinal detachment involving the macula was investigated retrospectively. The patients had been treated with a segmental or encircling scleral buckle procedure and in this study the follow-up period was between 5 and 11 years. In order to investigate the natural course of functional recovery of the reattached retina, all cases with a history of intraocular surgery or trauma were excluded. In this investigation, 34 patients were selected in which 35 eyes were studied. The best corrected visual acuities between a 6-month and 5-year postoperative period were compared. They were found to be more improved 5 years after surgery than after 6-month by two or more lines in 19 eyes (54%). In these 19 eyes, the visual acuities continued to improve up to 10 years after surgery. Improvement in the long-term postoperative visual acuity was found to correlate with the shorter duration of macular detachment (30 days), zero or mild myopia (-6 diopters) and to a lesser extent, retinal detachment. the visual function of the reattached human retinas may continue to improve over the long term, especially when these beneficial factors are present.

The electroretinogram in chronic renal failure.

To evaluate functional changes of the retina in patients with chronic renal failure (CRF), we analyzed maximal combined response according to the recommendations of the International Society of Clinical Electrophysiology of Vision. Oscillatory potentials were extracted from maximal combined response by high pass filtering. Because most CRF patients suffer from hypertension, hypertensive patients were selected for the control group. Values recorded in CRF patients were compared with those recorded in hypertensive patients and in the normal control group. CRF patients underwent laboratory tests which included complete blood cell count and the determination of blood urea nitrogen, creatinine, natrium, and potassium levels. The parameters of electroretinograms obtained from CRF patients were compared with those obtained from the normal control group, in the former group all amplitudes were significantly lower and all implicit times except those of b-wave were significantly delayed (P < 0.05). In CRF patients, decreased b-amplitude of maximal combined response and delayed implicit time of oscillatory potentials 1, and 2 were significantly different from those in hypertensive patients (P < 0.05). CRF patients had anemia, and their blood urea nitrogen and creatinine levels appeared abnormal. There was, however, no clinical correlation between biochemical data and electroretinograms. Consequently, retinal function in CRF patients was severely damaged compared with control groups (i.e., normal and hypertensive patients). We suggest that these findings are result of anemia and uremia in addition to hypertensive retinal damage.

Melanosomes of retinal pigment epithelium--distribution, shape, and acid phosphatase activity.

The distribution and shape of melanosomes of the retinal pigment epithelium (RPE), and acid phosphatase activity in melanosomes were studied in rabbits. The rabbit eyes were observed using electron microscopy and enzyme cytochemical electron microscopy. The majority of melanosomes were located near the apical region of the RPE. Melanosomes in the RPE were classified as two shapes, elliptical and spherical or oval. Elliptical melanosomes were located parallel to the apical process and spherical or oval melanosomes were arranged vertically or obliquely to the apical process. We think that the distribution and shape of melanosomes contributes to the effective absorption and blocking of light coming from all directions. Almost all of the mature and immature melanosomes we identified showed positive in acid phosphatase reaction, indicating that melanosomes are commonly incorporated into the lysosomal system of the RPE. However, a few melanosomes showed negative in acid phosphatase reaction, suggesting that some melanosomes are stable and inert. The observed premelanosome showed negative reaction. Two types of melanosome-related complex granules were identified; melanosomes with a cortex of enzyme-reactive material (melanolysosome) and melanosomes with a cortex of lipofuscin (melanolipofuscin). These findings indicate tha a relationship between melanosomes and the lysosomal system of the RPE exists, and suggest that melanosomes may undergo modification or degradation in the cytoplasm. Also, the observation of a premelanosome and the positive acid phosphatase activity in mature and immature melanosomes indicates that melanosomes of the RPE may continue to be synthesized at a low rate in adult eyes.

Hepatocellular carcinoma metastatic to the orbit.

Orbital metastases of hepatocellular carcinoma are rare. The authors report a case of hepatocellular carcinoma metastatic to the orbit. A 56-year-old woman with hepatitis B infection as confirmed serologic test for hepatitis B surface antigen (HBsAg) demonstrated superior displacement of the left eyeball. The clinical appearance of the patient demonstrated an inferior displacement of the right eye. MRI disclosed an orbital mass that extended toward the lower eyelid and into the temporal fossa with destruction of the lateral orbital wall. Upon subsequent abdominal computed tomographic scans, the primary tumor was found in the liver. A biopsy specimen of the orbit showed trabecular structures with eosinophilic cytoplasm. Bile canaliculi and sinusoids were also seen. The tumor cells showed vesicular nuclei with mitoses. Immunohistochemical markers such as high-molecular-weight keratin and alpha-fetoprotein showed a positive response. However, immunohistochemical markers such as low-molecular-weight keratin and polyclonal carcinoembryonic antigen showed as negative. We diagnosed the tumor as a hepatocellular carcinoma metastatic to the orbit. A review of the pertinent literature disclosed relatively few occurrences of hepatocellular carcinoma metastasizing to the orbit.

Electroretinographic studies in rhegmatogenous retinal detachment before and after reattachment surgery.

Changes in the scotopic electroretinogram (ERG) and oscillatory potentials (Ops) were examined in patients who had rhegmatogenous retinal detachment within 3 days before and also at regular intervals after a successful reattachment operation. Electroretinograms were recorded in 38 patients (age 10 to 62 years) for the recent 5 year period. The amplitudes of the scotopic a-wave and b-wave in the detached eye were significantly decreased compared to the fellow normal eye preoperatively. Statistically significant differences were found between the preoperative and the postoperative recordings of the diseased eye. However, postoperative interocular differences in the amplitude of the a-wave between the reattached and normal fellow eye were not statistically significant. The amplitudes of the a-wave and b-wave were inversely related to the extent of the retinal detachment area, the duration of the detachment, and the extent of the buckles that were applied. Significant interocular differences in the b/a wave amplitude ratio and the Ops amplitude were observed. These results strongly suggest that the retinal function, even after successful reattachment surgery, might be compromised mainly by an inner retinal malfunction rather than from a photoreceptor dysfunction.

Intraocular infusate with hemocoagulase for the control of bleeding during vitreous surgery.

The effects of hemocoagulase in injectable form (hemocoagulating enzymatic fraction of South American snake Bothrops jararaca venom provided by Ravizza) on the control of intraocular bleeding during vitreous surgery were evaluated in rabbit eyes. Intraocular infusion solution with hemocoagulase (1 NIH thrombin unit/100 ml of BSS plus) significantly reduced the bleeding time. Electroretinogram b-wave and electroretinogram c-wave showed no abnormality. Infusate with hemocoagulase (1 NIH thrombin unit/100 ml of BSS plus) is not toxic to retinal tissue and appeared to be a useful agent for the control of intraocular bleeding during vitreous surgery.

Efficacy of ciprofloxacin and dexamethasone in experimental pseudomonas endophthalmitis.

To determine injection time and effective dose of ciprofloxacin in endophthalmitis and to evaluate the effectiveness of dexamethasone. In rabbits, Pseudomonas aeruginosa (2 x 10(4) CFU/0.1 ml) was inoculated intravitreally. At 6, 12, 18, 24 hours postinoculation, single intravitreal doses of ciprofloxacin (300 micrograms/0.15 ml or 100 micrograms/0.05 ml) alone or with dexamethasone (400 micrograms) were given. Electrophysiological and histologic measures were utilized to rate drug effectiveness. 300 micrograms ciprofloxacin was effective in killing P. aeruginosa at 6 and 12 hours postinoculation, but one hundred ug ciprofloxacin was not effective. 300 ug ciprofloxacin had no significant effect in killing P. aeruginosa at 18 hrs and 24 hrs postinoculation. Eyes treated with dexamethasone (400 micrograms) and ciprofloxacin (300 micrograms) at 6 hours postinoculation did not differ from eyes treated with ciprofloxacin alone. Cultures from eyes treated with dexamethasone and ciprofloxacin at 12 hours postinoculation were positive. Cultures from eyes treated with ciprofloxacin alone were negative. The failure of treatment at 18 hrs and 24 hrs postinoculation may be due to either an increased rate of clearance of drugs from the eyes or a reduced bactericidal effect of ciprofloxacin which could be altered by acidic pH, degree of hypoxia or bacterial counts. Dexamethasone had no beneficial effect in the treatment of P. aeruginosa endophthalmitis in the early phase.

Continued lodging of retinal emboli in a patient with internal carotid artery and ophthalmic artery occlusions.

Internal carotid artery or ophthalmic artery occlusions are devastating ophthalmological events which lead to severe impairment of vision. A case of multiple branch retinal artery occlusions in a 63-year-old male with internal carotid artery and ophthalmic artery occlusions on brain angiography is presented. Emboli lodging in branches of the retinal arteries were bright, glistening, yellow or orange in appearance. Such a distinctive ophthalmoscopic appearance led to the diagnosis of cholesterol emboli. Fluorescein and indocyanine green angiography disclosed delayed filling of the retinal vessels and choroid, and showed multiple hypofluorescence distal to the vessels in which the emboli were lodged. At the time of initial examination, the number of emboli lodged in retinal arteries was estimated at more than 20. As time passed, a few of the previous emboli disappeared and new emboli appeared in other sites on fundus examination. We think that the lodging of new emboli in other sites is due to the continued break-up of atheromatous tissue through the collateral circulation associated with the occlusion of the internal carotid and ophthalmic arteries.

Central retinal vein occlusion combined with cilioretinal artery occlusion.

A healthy 65-year-old man with sudden profound visual loss in his right eye presented with clinical signs of central retinal venous occlusion and retinal whitening, indicative of a cilioretinal arterial obstruction. He had been diagnosed with cilioretinal artery occlusion at a private ophthalmology clinic three days before being referred to our department. On fluorescein angiogram of the affected eye, the proximal portion of the retinal arteries filled with dye 27.3 seconds after injection, indicating a delay in retinal arterial filling. Moreover, the cilioretinal artery did not fill at that phase, but went on to fill 45.1 seconds after injection. Over 63.4 seconds after the filling of the retinal arteries, the laminar flow of the retinal venous vessels appeared. This was not until 90.7 seconds after injection. This patient was elderly, had no systemic diseases, and showed non-ischemic CRVO, prolonged retinal arterial filling on fluorescein angiography, and poor prognosis in visual acuity. His clinical course seemed to favor the pathogenetic hypothesis of a primary arterial affection.

Mitomycin C-induced apoptosis in cultured human Tenon's capsule fibroblasts.

To investigate the mitomycin C-induced apoptotic cell death of fibroblasts, the primarily cultured human Tenon's capsule fibroblasts were exposed to a clinically used dosage of 0.4 mg/ml of mitomycin C for 5 minutes. TUNEL (TdT-mediated dUTP-biotin nick end labeling) assay and electron microscopic studies were performed to determine the extent of mitomycin C-induced apoptosis. A flow cytometric study was performed to quantify the apoptotic cell population over time. The TUNEL stains were positive and electron microscopy showed features of apoptotic cell death in some fibroblasts 3 and 5 days after treatment. Flow cytometric analysis using Annexin V-propidium iodide double staining detected apoptotic cells 3 days after treatment. These apoptotic cell populations increased at 4 days and were sustained for one week. This study revealed that the clinical effects of mitomycin C on fibroblasts may be mediated not only by antiproliferative but also apoptotic cell death to some degree. Therefore, the apoptotic cell death of fibroblasts induced by mitomycin C should be considered to properly understand the mechanism of wound healing after trabeculectomy with adjunctive mitomycin C.

Normal range of exophthalmos values on orbit computerized tomography in Koreans.

The value of parameters in Hertel's exophthalmometry was measured by using orbit computerized tomography (CT) in this study. We selected images that revealed the center of the lens, the largest eyeball contour and the optic canal on the axial view of orbit CT. Parameters of exophthalmometry on orbit CT were the distance between the lateral orbital rims of both eyes (A), the shortest distance from the corneal center to line A (B), the B/A ratio, the distance between the lateral orbital rim and the medial orbital rim (C), the length of the line passing through the lens center from the apex to line C (D) and the D/C ratio. To compare the center position of the eye, we measure the axial length (E) and the longest distance between the corneal apex and the posterior pole (F) which is parallel to line B. We also calculated B-F/2 and Hertel-F/2 in order to know if there is a difference between measurements of orbit CT and of Hertel's exophthalmometer. Subjects were classified into group 1 (aged 8-13 years old) and group 2 (aged 20 years old more). Sixteen subjects were enrolled in group 1 (32 eyes). In group 2, 100 subjects were male (200 eyes) and 35 were female (70 eyes). In group 1, the mean value was 89.94 mm for A, 13.49 mm for B, 35.13 mm for C, 10.64 mm for D, 24.40 mm for E, 24.20 mm for F, 0.15 for the B/A ratio and 0.30 for the D/C ratio. In group 2, the mean value was 100.93 mm for A, 15.03 mm for B, 38.78 mm for C, 12.03 mm for D, 24.62 mm for E, 24.33 mm for F, 0.15 for the B/A ratio and 0.31 for the D/C ratio. There was a statistically significant difference between the two groups for parameters A, B, C and D (p = 0.001), but no significant difference for the B/A (p = 0.239) and D/C ratios (p = 0.803). In the males and females of group 2, there was a statistically significant difference for the B/A ratio (p = 0.028). We suggest that the value of the D/C ratio (0.30-0.31) could be used as the index of protrusion. The normal values of exophthalmometry parameters measured by orbit CT could also be helpful to evaluate the exact protrusion in orbital diseases.