Microstructurally Tailored Thin ß-Ag2 Se Films toward Commercial Flexible Thermoelectrics.

Aiming to overcome both the structural and commercial limitations of flexible thermoelectric power generators, an efficient room-temperature aqueous selenization reaction that can be completed in air within less than 1 min, to directly fabricate thin ß-Ag2 Se films consisting of perfectly crystalline and large columnar grains with both in-plane randomness and out-of-plane [201] preferred orientation, is designed. A high power factor (PF) of 2590 ± 414 µW m-1 K-2 and a figure-of-merit (zT) of 1.2 ± 0.42 are obtained from a sample with a thickness of ≈1 µm. The maximum output power density of the best 4-leg thermoelectric generator sample reach 27.6 ± 1.95 and 124 ± 8.78 W m-2 at room temperature with 30 and 60 K temperature differences, respectively, which may be useful in future flexible thermoelectric devices.

Flexible n-Type Abundant Chalcopyrite/PEDOT:PSS/Graphene Hybrid Film for Thermoelectric Device Utilizing Low-Grade Heat.

Combining inorganic thermoelectric (TE) materials with conductive polymers is one promising strategy to develop flexible thermoelectric (FTE) films and devices. As most inorganic materials tried up until now in FTE composites are composed of scarce or toxic elements, and n-type FTE materials are particularly desired, we combined the abundant, inexpensive, nontoxic Zn-doped chalcopyrite (Cu1-xZnxFeS2, x = 0.01, 0.02, 0.03) with a flexible electrical network constituted by poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) and graphene for n-type FTE films. Hybrid films from the custom design of binary Cu1-xZnxFeS2/PEDOT:PSS to the optimum design of ternary Cu0.98Zn0.02FeS2/PEDOT:PSS/graphene are characterized. Compared with the binary film, a 4-fold enhancement in electrical conductivity was observed in the ternary film, leading to a maximum power factor of ∼ 23.7 µW m-1 K-2. The optimum ternary film could preserve >80% of the electrical conductivity after 2000 bending cycles, exhibiting an exceptional flexibility due to the network constructed by PEDOT:PSS and graphene. A five-leg thermoelectric prototype made of optimum films generated a voltage of 4.8 mV with a ΔT of 13 °C. Such an evolution of an inexpensive chalcopyrite-based hybrid film with outstanding flexibility exhibits the potential for cost-sensitive FTE applications.

Thermoelectric Performance Enhancement of Film by Pulse Electric Field and Multi-Nanocomposite Strategy.

Thermoelectric (TE) film has wide potential application in low-grade waste heat recovery and TE generation due to its quick response and multifunctional integration. Multi-nanocomposite is a promising method to solve the difficulty of maintaining temperature difference and achieving a high figure of merit ZT. However, the depletion layer induced by the multi-nanocomposite typically degrades performance. This study presents a simple and convenient method to solve this problem by pulse electric field (PEF). Prototypical TE Bi2 Te3 is selected as the objective film. The strong current density effect of PEF removes the depletion layer among carbon nanotubes (CNT) and Bi2 Te3 grains. Thus, the CNT nanocomposite with PEF treatment breaks the trade-off between electrical conductivity and Seebeck coefficient, achieving a power factor of 4400 µW m-1 K-2 which stabilizes after annealing effect to 2920 µW m-1 K-2 , a record for Bi2 Te3 films. Simultaneously, the self-assembled porosity decreases thermal conductivity via phonon scattering while still maintaining a high electrical conductivity of 3130 S cm-1 . Thus, the porosity helps maintain the temperature difference and thereby enables a sharp increase in output power. These results indicate that the combination of PEF and multi-nanocomposite is a new method to enhance TE performance, which would have a potential application in the commercial field.

Experimental investigation of reciprocity of temperature response across two layer samples by flash method.

The reciprocity of heat transfer is a fundamental principle. However, there are few experimental studies to verify this principle. In this paper, we measured two layer samples made of ordinary metal by the laser flash method to verify the reciprocity principle. We heated and detected the different surfaces of each two layer sample to observe the reciprocal response. We also made use of areal heat diffusion time to analyze the temperature rise of two layer samples to enable to extend analysis for future multi-layer samples. This study is an important starting point to discuss whether characteristic materials obey the reciprocal principle.

Drastic power factor improvement by Te doping of rare earth-free CoSb3-skutterudite thin films.

In the present study, we have focused on the elaboration of control of Te-doped CoSb3 thin films by RF magnetron sputtering which is an attractive technique for industrial development of thermoelectric (TE) thin films. We have successfully synthesized sputtering targets with a reliable approach in order to obtain high-quality films with controlled stoichiometry. TE properties were then probed and revealed a reliable n-type behavior characterized by poor electrical transport properties. Tellurium substitution was realized by co-sputtering deposition and allowed obtaining a significant enhancement of the power factor with promising values of PF ≈ 0.21 mW m-1 K-2 near room temperature. It is related to the Te doping effect which leads to an increase of the Seebeck coefficient and the electrical conductivity simultaneously. However, despite this large improvement, the properties remained far from the bulk material and further developments are necessary to improve the carrier mobility reduced by the thin film formatting.

Characteristics of early filtering blebs that predict successful trabeculectomy identified via three-dimensional anterior segment optical coherence tomography.

BACKGROUND/AIMS: To identify the cross-sectional characteristics of filtering blebs at 2 weeks post-trabeculectomy associated with intraocular pressure (IOP) control at 1 year post-trabeculectomy. METHODS: Ninety-nine eyes of 94 patients who had undergone primary trabeculectomy were included in this retrospective consecutive case series study. Surgical success was defined as an IOP ≤15 mm Hg and a >20% reduction in IOP without glaucoma medication or additional glaucoma surgeries at 1 year post-trabeculectomy. Subjects were classified into two groups according to whether surgery was successful or unsuccessful. Blebs were examined using swept-source three-dimensional anterior segment optical coherence tomography and evaluated for quantitative parameters, including maximum height, maximum wall thickness and ratio of hyporeflective space of the wall, as well as qualitative parameters, including multiple parallel hyporeflective layers within the wall (striping phenomenon), decreased visibility of the sclera underlying the bleb (shading phenomenon) and cyst-like structures of the wall. RESULTS: Seventy-seven eyes (77.8%) were assigned to the successful group and 22 (22.2%) to the unsuccessful group. Univariate analysis showed significant differences between the groups regarding maximum bleb height (p=0.044), maximum bleb wall thickness (p=0.017) and the striping phenomenon of the bleb wall (p=0.007). Multivariate logistic regression analysis confirmed that the striping phenomenon at 2 weeks post-trabeculectomy was significantly associated with success at 1 year post-trabeculectomy (OR 3.405; 95% CI 1.059 to 10.947; p=0.040). CONCLUSION: Taller blebs with thicker walls that showed the striping phenomenon at 2 weeks post-trabeculectomy appeared to predict good IOP control at 1 year post-trabeculectomy.

The signs of ocular-surface disorders after switching from latanoprost to tafluprost/timolol fixed combination: a prospective study.

PURPOSE: To evaluate the ocular-surface safety of a 0.001% benzalkonium chloride-containing tafluprost/timolol fixed combination (TTFC) in patients with primary open-angle glaucoma (POAG) or ocular hypertension who have inadequate intraocular pressure (IOP) control with latanoprost monotherapy. METHODS: This study is a multicenter, prospective, single-arm, open-label clinical study. Patients with POAG or ocular hypertension who have inadequate IOP control with latanoprost monotherapy were considered eligible. After providing informed consent, patients continued latanoprost monotherapy for 12 weeks, followed by a switch to TTFC. We evaluated the extent of ocular-surface damage using superficial punctate keratopathy (SPK) score, tear breakup time (TBUT), hyperemia score, IOP, systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate at 0, 4, and 12 weeks after switching. RESULTS: A total of 68 patients were enrolled, of whom, 64 patients were included in the final analysis. No significant changes in SPK score, TBUT, or hyperemia score were observed at 4 and 12 weeks compared with week 0. IOP decreased significantly at 4 (13.9±2.5 mmHg) and 12 (14.1±2.5 mmHg) weeks, relative to week 0 (15.3±2.7 mmHg). No significant changes in either SBP or DBP were observed during the study, although patients' mean heart rate decreased significantly after switching to TTFC. Adverse drug reactions to TTFC occurred in seven patients including two incidences of asthma and one of arrhythmia, and no events were serious. CONCLUSION: The ocular-surface safety of TTFC is not significantly different to that of latanoprost. Furthermore, switching from latanoprost to TTFC in patients with insufficient IOP control has additive IOP-lowering effects. TTFC is an effective approach for patients receiving latanoprost monotherapy who require more intensive IOP reduction.

Characteristics of successful filtering blebs at 1 year after trabeculectomy using swept-source three-dimensional anterior segment optical coherence tomography.

PURPOSE: To identify the cross-sectional characteristics of filtering blebs associated with intraocular pressure (IOP) control at 1 year after trabeculectomy with a square scleral flap and a fornix-based conjunctival flap. METHODS: A retrospective consecutive case series study was conducted. Eighty-four eyes of 79 patients who had undergone primary trabeculectomy were included. Surgical success was defined as IOP ≤15 mmHg and a >20% reduction in IOP without glaucoma medication and without additional glaucoma surgery at 1 year after trabeculectomy. The subjects were classified into two groups according to whether surgery was successful or unsuccessful. Filtering blebs were examined using swept-source three-dimensional anterior segment optical coherence tomography and evaluated for the following quantitative parameters: maximum bleb height, maximum bleb wall thickness, and ratio of hypo-reflective space of the bleb wall. RESULTS: Sixty-six eyes were determined to be successful and 18 eyes unsuccessful. Univariate analysis showed significant differences between the two groups regarding bleb height (P < 0.001), bleb wall thickness (P = 0.011), and ratio of hypo-reflective space of the bleb wall (P = 0.002). Multivariate logistic regression analysis confirmed that the bleb height was significantly associated with success in trabeculectomy [odds ratio 13.996 (95% confidence interval 1.184-165.420); P = 0.036]. CONCLUSION: A tall bleb with a thick hypo-reflective wall may be a feature of the well-functioning bleb.

Evaluation of relationship between retinal nerve fiber layer thickness progression and visual field progression in patients with glaucoma.

PURPOSE: To evaluate the capability of optical coherence tomography (OCT), retinal nerve fiber layer (RNFL) thickness, and visual field (VF) measurements in glaucoma progression detection. METHODS: The study examined 62 eyes of 37 glaucoma patients observed over a 3-year period. All eyes underwent at least four serial RNFL measurements performed by Cirrus OCT, with the first and last measurements separated by at least 3 years. VF testing was performed by using the Swedish interactive threshold algorithm (SITA) Standard 30-2 program of the Humphrey field analyzer (HFA) on the same day as the RNFL imaging. Both serial RNFL thicknesses and VF progression were assessed by the guided progression analysis (GPA) software program. RNFL thickness progression was evaluated by event analysis. Total deviation (TD) in the superior or inferior hemifield was also examined. RESULTS: A total of 295 OCT scans and 295 VFs were analyzed. Five eyes exhibited progression by OCT only and 8 eyes exhibited progression by VF GPA only. When the analysis was based on the combined measurement findings, progression was noted in 6 eyes. The average of the progressive hemifield TD at baseline for combined RNFL and VF progression was -3.21±1.38 dB, while it was -2.17±1.14 dB for RNFL progression and -9.12±3.75 dB for VF progression. The average of the progressive hemifield TD indicated a significant advancement of VF progression as compared to RNFL progression (P=0.002). CONCLUSIONS: When a mild VF defect is present, OCT RNFL thickness measurements are important in helping discern glaucoma progression.

Correlation between the ganglion cell-inner plexiform layer thickness measured with cirrus HD-OCT and macular visual field sensitivity measured with microperimetry.

PURPOSE: To evaluate relationships between the macular visual field (VF) mean sensitivity and the ganglion cell and inner plexiform layer (GCA) thicknesses. METHODS: Seventy-one glaucoma patients and 29 healthy subjects were included in this cross-sectional study. At each visit, GCA thicknesses were measured by Cirrus HD-OCT and static threshold perimetry was performed using Macular Integrity Assessment (MAIA). The relationship between the VF sensitivity and GCA thickness was examined globally, and in the superior hemiretina, inferior hemiretina, and six VF sectors with both VF and optical coherence tomography (OCT) in retinal view. Regression analysis was used to investigate the relationship between the GCA thickness and macular sensitivity. RESULTS: Macular VF sensitivity (dB) and GCA thickness relationships were statistically significant in each sector (R = 0.365-0.706, all P < 0.001). The highest correlation observed was between the inferotemporal average mean sensitivity and the inferotemporal average GCA thickness (R = 0.706) with both VF and OCT in retinal view. Strength of the structure-function relationship for each of the corresponding inferior sectors was higher than those for the corresponding superior sectors. The strength of the structure-function relationship of the temporal sector was higher than that of the nasal sector. CONCLUSIONS: GCA thickness measured by Cirrus HD-OCT showed statistically significant structure-function associations with central VF. Inferotemporal central VF had the strongest association.

Evaluation of peripapillary choroidal thickness in patients with normal-tension glaucoma.

BACKGROUND: To compare peripapillary choroidal thickness measurements between normal and normal-tension glaucoma eyes. METHODS: Cross-sectional comparative study. 50 normal and 52 normal-tension glaucoma subjects were enrolled in the study. Peripapillary choroidal thickness was measured with spectral-domain optical coherence tomography and enhanced depth imaging. After obtaining circular B-scans around the disc, choroidal thicknesses were calculated based on the exported segmentation values. Visual fields were measured using automated perimetry. Difference in peripapillary choroidal thickness between the normal subjects and the patients with normal-tension glaucoma was analyzed. RESULTS: There were no significant differences in age, axial length, or refraction between the two groups. Peripapillary choroidal thickness was inversely correlated with age in both the normal (r = -0.287, P = 0.04) and normal and normal-tension glaucoma (r = -0.322, P = 0.02) groups. Peripapillary choroidal thickness of inferonasal (125 vs 148 µm, P < 0.05), inferior (101 vs 122 µm, P < 0.05), or inferotemporal (100 vs 127 µm, P < 0.05) regions were significantly thinner in the normal-tension glaucoma group as compared to normal subjects. Superior visual hemifield defect was significantly worse than inferior visual hemifield defect in normal and normal-tension glaucoma patients. CONCLUSION: As compared to normal subjects, peripapillary choroidal thickness was significantly thinner in the normal and normal-tension glaucoma patients, at least in some locations.

Comparison of optic nerve head parameters using Heidelberg Retina Tomograph 3 and spectral-domain optical coherence tomography.

BACKGROUND: To assess the agreement between the Heidelberg Retina Tomograph and Cirrus spectral-domain optical coherence tomography (Cirrus HD-OCT [Carl Zeiss Meditec, Dublin, CA, USA]) when measuring optic disc parameters. DESIGN: Prospective, cross-sectional study. PARTICIPANTS: A total of 96 glaucoma patients and 21 normal subjects were analysed. METHODS: Optic nerve head measurements, including disc area, rim area, cup-to-disc ratio and cup volume were obtained using both the Cirrus HD-OCT and Heidelberg Retina Tomograph 3 (Heidelberg Engineering GmbH, Heidelberg, Germany). MAIN OUTCOME MEASUREMENTS: Bland-Altman plots were used to evaluate the agreement between each of the optic disc parameters. RESULTS: Although Cirrus HD-OCT values were smaller than Heidelberg Retina Tomograph 3 values for the disc and rim areas, overall the Cirrus HD-OCT and Heidelberg Retina Tomograph 3 measurements were highly correlated (r = 0.657 to 0.821). As compared with Heidelberg Retina Tomograph 3, disc and rim areas tended to be minimized by Cirrus HD-OCT, especially when there were large disc and rim areas, although there was no relationship between the discrepancy and the level of measurement of the cup-to-disc ratio. The optical coherence tomography overestimated the Heidelberg Retina Tomograph-determined cup volume, especially when there were large cup volumes. CONCLUSIONS: Bland-Altman analyses revealed that with the exception of the cup-to-disc ratio, there was poor agreement between the Cirrus HD-OCT and Heidelberg Retina Tomograph 3 morphometric measurements. In addition, with the exception of the cup-to-disc ratio, the optic nerve head measurements could not be directly compared between the Cirrus HD-OCT and Heidelberg Retina Tomograph 3.

Relationship between progression of visual field damage and choroidal thickness in eyes with normal-tension glaucoma.

BACKGROUND: To measure choroidal thickness in normal eyes and in patients with normal-tension glaucoma using enhanced depth imaging optical coherence tomography and evaluate the association between choroidal thickness and progression of visual field damage. DESIGN: Cross-sectional comparative study. PARTICIPANTS: A total of 62 eyes of 62 normal subjects and 45 eyes of 45 normal-tension glaucoma patients were examined. METHODS: The choroid was measured at the fovea and 3 mm nasal and temporal from the fovea. In the separate study, both eyes of the patients with normal-tension glaucoma were included in the analyses. Visual fields were measured with automated perimetry. Changes in mean deviation per year (dB/year), that is, mean deviation slope, were calculated. MAIN OUTCOME MEASURES: Difference in the choroidal thickness between the normal subjects and the patients with normal-tension glaucoma. The relationship between mean deviation slope and the choroidal thickness in eyes with normal-tension glaucoma was analysed. RESULTS: Compared with normal subjects, the choroidal thickness was significantly thinner in eyes with normal-tension glaucoma at 3 mm nasal from the fovea (P = 0.02). There was a significant correlation between the choroidal thickness at 3 mm nasal from the fovea and the mean deviation slope (Pearson's r = 0.413; P < 0.001). CONCLUSION: The decrease in the thickness of the choroid at 3 mm nasal from the fovea in eyes with normal-tension glaucoma may be associated with progressive visual field loss. Thus, choroidal abnormalities may play a role in the pathogenesis of normal-tension glaucoma.

Efficacy and safety of switching from topical latanoprost to bimatoprost in patients with normal-tension glaucoma.

PURPOSE: The aim of this study was to evaluate the efficacy and safety of bimatoprost in Japanese patients with normal-tension glaucoma (NTG) who showed insufficient response to latanoprost. METHODS: A prospective, nonrandomized study was conducted in patients with NTG, with ≤20% intraocular pressure (IOP) decrease from pretreatment baseline with latanoprost monotherapy who had been switched to bimatoprost. The IOP was measured at 4, 8, and 12 weeks after the switch to bimatoprost. In 12 weeks after the switch to bimatoprost, efficacy and safety were evaluated. RESULTS: Postswitch to bimatoprost, IOP was significantly reduced at every visit. Bimatoprost produced significantly greater mean% IOP reduction rate from pretreatment than that of latanoprost at week 12 (P<0.01). There was a significant correlation between% IOP reduction of bimatoprost and that of latanoprost (Pearson r(2)=0.374; P=0.007). No significant difference was observed in the mean scores of conjunctival hyperemia and corneal epithelial disorder between bimatoprost-treated eyes and latanoprost-treated eyes. CONCLUSIONS: Significant additional IOP lowering was achieved by switching to bimatoprost in Japanese patients with NTG with insufficient response to latanoprost. Bimatoprost treatment was safe and well tolerated.

Comparison of retinal nerve fiber layer thickness measurements using time domain and spectral domain optical coherence tomography, and visual field sensitivity.

PURPOSE: To investigate the relationship between the peripapillary retinal nerve fiber layer (RNFL) thickness, as measured by Stratus time domain optical coherence tomography (OCT) (Stratus OCT) and Cirrus spectral domain OCT (Cirrus HD-OCT), and the severity indices of the visual field (VF) defects in glaucoma patients. METHODS: This was a prospective, cross-sectional study. Correlations between the individual VF sensitivity at 52 test points and the Stratus OCT and Cirrus HD-OCT, which determined peripapillary RNFL thicknesses from 6 sectors, were calculated in 54 eyes with open-angle glaucoma and 22 normal control eyes. The association between the RNFL thickness and VF sensitivity was evaluated using a second-order regression model. RESULTS: A significant correlation was found for the RNFL thicknesses determined by the 2 OCT devices (r=0.51 to 0.95; P<0.001). VF sensitivities at each test point were also significantly correlated with the sectoral RNFL thicknesses. The inferotemporal RNFL sector exhibited the highest coefficient of determination, whereas the superotemporal test point had the highest VF sensitivity (Stratus, 0.70; Cirrus, 0.62). CONCLUSIONS: The structure-function relationship was comparable between Cirrus HD-OCT and Stratus OCT RNFL measurements.

Comparison of ICare rebound tonometer with noncontact tonometer in healthy children.

PURPOSE: To evaluate the effectiveness of using a noncontact tonometer (NCT) versus a rebound tonometer (ICare) when measuring the intraocular pressure (IOP) in healthy children. DESIGN: Prospective observational study. METHODS: A total of 180 (96 males and 84 females) healthy children, aged 6 months to 15 years, were recruited. IOPs were measured using both the NCT and ICare devices in the absence of anesthesia. A successful outcome was defined as the measurement of the IOP in both eyes. The McNemar test for comparing correlated proportions was used to analyze the ICare and NCT data. RESULTS: Although the IOP was successfully measured in 160 children (88.9%) when using ICare, we were only able to successfully measure 130 children (72.2%) when using NCT. Below the age of 6 years, measurement of the IOP using ICare was better tolerated as compared with the NCT (McNemar test; P<0.001). The mean differences (95% limits of agreement) for the IOP readings between ICare and NCT in right and left eyes were 0.90±6.40 and 1.18±6.19 mm Hg, respectively. CONCLUSIONS: IOP measurements performed using ICare are better tolerated in the pediatric population, as compared with measurements using NCT, especially in children below the age of 6 years.

Stratus optical coherence tomography study of filtering blebs after primary trabeculectomy with a fornix-based conjunctival flap.

PURPOSE: To investigate the relationship between filtering bleb function and Stratus optical coherence tomography (OCT) images. METHODS: We studied 72 eyes of 65 consecutive patients who had a fornix-based conjunctival flap in primary trabeculectomy with mitomycin C (MMC). Filtering blebs with various types of glaucoma were examined using Stratus OCT. Success rates were defined as intraocular pressure (IOP) < or = 15 mmHg and IOP reduction > or = 25% without medication or additional surgery. Success rates among classified groups were compared using Kaplan-Meier survival curves and the log-rank test. RESULTS: Blebs were classified into three different categories on the basis of the following Stratus OCT patterns: cystoid type (multiple cysts inside the bleb; 17 eyes), diffuse type (low to high reflective areas that were mixed inside the bleb; 31 eyes) and layer type (medium to high reflective layer inside the bleb; 24 eyes). Success rates in the cystoid-, diffuse- and layer-type blebs were 94%, 97% and 75% (P = 0.02), respectively. CONCLUSION: In trabeculectomy with MMC and a fornix-based conjunctival flap, there is a significant association between the success rates and the postoperative Stratus OCT findings of filtering blebs.

Effect of trabeculectomy on intraocular pressure fluctuation with postural change in eyes with open-angle glaucoma.

PURPOSE: To investigate the effect of trabeculectomy on the intraocular pressure (IOP) fluctuations caused by the postural change in patients with open-angle glaucoma. METHODS: Prospective, nonrandomized study. Ten eyes of 10 patients with primary open-angle glaucoma and 3 eyes of 3 patients with normal-tension glaucoma who underwent trabeculectomy were studied. The IOP at the baseline and 3 months after trabeculectomy was measured in both sitting and supine positions. A pneumatonometer was used to measure the IOP in both sitting and supine position. RESULTS: The mean IOP in the sitting position was 19.6+/-5.1 mm Hg at the baseline and 9.4+/-2.9 mm Hg after trabeculectomy (P<0.01, paired t test). The mean difference in IOP between the sitting and supine position was 4.1+/-1.6 mm Hg at the baseline and 2.2+/-1.5 mm Hg after trabeculectomy (P=0.01, paired t test). CONCLUSIONS: Trabeculectomy might decrease not only the IOP in the sitting position but also the magnitude of IOP elevation associated with the postural change.