Asymmetry Analysis of Macular Inner Retinal Layers for Glaucoma Diagnosis: Swept-Source Optical Coherence Tomography Study.

PubMed

Lee, Sang-Yoon; Lee, Eun Kyoung; Park, Ki Ho; Kim, Dong Myung; Jeoung, Jin Wook

2016-01-01

To report an asymmetry analysis of macular inner retinal layers using swept-source optical coherence tomography (OCT) and to evaluate the utility for glaucoma diagnosis. Observational, cross-sectional study. Seventy normal healthy subjects and 62 glaucoma patients. Three-dimensional scans were acquired from 70 normal subjects and 62 open angle glaucoma patients by swept-source OCT. The thickness of the retinal nerve fiber layer, ganglion cell-inner plexiform layer (GCIPL), ganglion cell complex, and total retina were calculated within a 6.2×6.2 mm macular area divided into a 31×31 grid of 200×200 μm superpixels. For each of the corresponding superpixels, the thickness differences between the subject eyes and contra-lateral eyes and between the upper and lower macula halves of the subject eyes were determined. The negative differences were displayed on a gray-scale asymmetry map. Black superpixels were defined as thickness decreases over the cut-off values. The negative inter-ocular and inter-hemisphere differences in GCIPL thickness (mean ± standard deviation) were -2.78 ± 0.97 μm and -3.43 ± 0.71 μm in the normal group and -4.26 ± 2.23 μm and -4.88 ± 1.46 μm in the glaucoma group. The overall extent of the four layers' thickness decrease was larger in the glaucoma group than in the normal group (all Ps<0.05). The numbers of black superpixels on all of the asymmetry maps were larger in the glaucoma group than in the normal group (all Ps<0.05). The area under receiver operating characteristic curves of average negative thickness differences in macular inner layers for glaucoma diagnosis ranged from 0.748 to 0.894. The asymmetry analysis of macular inner retinal layers showed significant differences between the normal and glaucoma groups. The diagnostic performance of the asymmetry analysis was comparable to that of previous methods. These findings suggest that the asymmetry analysis can be a potential ancillary diagnostic tool.

Correlated alterations in prostate basal cell layer and basement membrane

PubMed Central

Liu, Aijun; Wei, Lixin; Gardner, William A.; Deng, Chu-Xia; Man, Yan-Gao

2009-01-01

Our recent studies revealed that focal basal cell layer disruption (FBCLD) induced auto-immunoreactions represented a contributing factor for human prostate tumor progression and invasion. As the basement membrane surrounds and attaches to the basal cell layer, our current study assessed whether FBCLD would impact the physical integrity of the associated basement membrane. Paraffin sections from 25-human prostate tumors were subjected to double immunohistochemistry to simultaneously elucidate the basal cell layer and the basement membrane with corresponding biomarkers. The physical integrity of the basement membrane overlying FBCLD was examined to determine the extent of correlated alterations. Of a total of 89 FBCLD encountered, 76 (85 %) showed correlated alterations in the overlying basement membrane, which included distinct focal disruptions or fragmentations. In the remaining 13 (15%) FBCLD, the overlying basement membrane showed significant attenuation or reduction of the immunostaining intensity. The basement membrane in all or nearly all ducts or acini with p63 positive basal cells was substantially thicker and more uniform than that in ducts or acini without p63 positive basal cells, and also, a vast majority of the focal disruptions occurred near basal cells that lack p63 expression. These findings suggest that focal disruptions in the basal cell layer and alterations in the basement membrane are correlated events and that the physical and functional status of the basal cells could significantly impact the physical integrity of the overlying basement membrane. As the degradation of both the basal cell layer and the basement membrane is a pre-requisite for prostate tumor invasion or progression, ducts or acini with focally disrupted basal cell layer and basement membrane are likely at greater risk to develop invasive lesions. Thus, further elucidation of the specific molecules and mechanism associated with these events may lead to the development of a more effective alternative for repeat biopsy to monitor tumor progression and invasion. PMID:19343113

Internal configuration of prismatic lithium-ion cells at the onset of mechanically induced short circuit

DOE PAGES

Wang, Hsin; Simunovic, Srdjan; Maleki, Hosein; ...

2016-01-01

The response of Li-ion cells to mechanically induced internal electrical shorts is an important safety performance metric design. We assume that the battery internal configuration at the onset of electrical short influences the subsequent response and can be used to gauge the safety risk. We subjected a series of prismatic Li-ion cells to lateral pinching using 0.25", 0.5", 1", 2" and 3" diameter steel balls until the onset of internal short. The external aluminum enclosure froze the internal cell configuration at the onset of short and enabled us to cross-section the cells, and take the cross-section images. The images indicatemore » that an internal electric short is preceded by extensive strain partitioning in the cells, fracturing and tearing of the current collectors, and cracking and slipping of the electrode layers with multiple fault lines across multiple layers. These observations are at odds with a common notion of homogeneous deformation across the layers and strain hardening of electrodes that eventually punch through the separator and short the cell. The faults are akin to tectonic movements of multiple layers that are characteristic of granular materials and bonded aggregates. As a result, the short circuits occur after extensive internal faulting, which implies significant stretching and tearing of separators.« less

Structure and chemical organization of the accessory olfactory bulb in the goat.

PubMed

Mogi, Kazutaka; Sakurai, Katsuyasu; Ichimaru, Toru; Ohkura, Satoshi; Mori, Yuji; Okamura, Hiroaki

2007-03-01

The structure and chemical composition of the accessory olfactory bulb (AOB) were examined in male and female goats. Sections were subjected to either Nissl staining, Klüver-Barrera staining, lectin histochemistry, or immunohistochemistry for nitric oxide synthase (NOS), neuropeptide Y (NPY), tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and glutamic acid decarboxylase (GAD). The goat AOB was divided into four layers: the vomeronasal nerve layer (VNL), glomerular layer (GL), mitral/tufted (M/T) cell layer (MTL), and granule cell layer (GRL). Quantitative and morphometric analyses indicated that a single AOB contained 5,000-8,000 putative M/T cells with no sex differences, whereas the AOB was slightly larger in males. Of the 21 lectins examined, 7 specifically bound to the VNL and GL, and 1 bound not only to the VNL, but also to the MTL and GRL. In either of these cases, no heterogeneity of lectin staining was observed in the rostrocaudal direction. NOS-, TH-, DBH-, and GAD-immunoreactivity (ir) were observed in the MTL and GRL, whereas NPY-ir was present only in the GRL. In the GL, periglomerular cells with GAD-ir were found in abundance, and a subset of periglomerular cells containing TH-ir was also found. Double-labeling immunohistochemistry revealed that virtually all periglomerular cells containing TH-ir were colocalized with GAD-ir.

Different characteristics of mesenchymal stem cells isolated from different layers of full term placenta

PubMed Central

Ha, Chul-Won; Kim, Jin A; Heo, Jin-Chul; Han, Woo-Jung; Oh, Soo-Young; Choi, Suk-Joo

2017-01-01

Background The placenta is a very attractive source of mesenchymal stem cells (MSCs) for regenerative medicine due to readily availability, non-invasive acquisition, and avoidance of ethical issues. Isolating MSCs from parts of placenta tissue has obtained growing interest because they are assumed to exhibit different proliferation and differentiation potentials due to complex structures and functions of the placenta. The objective of this study was to isolate MSCs from different parts of the placenta and compare their characteristics. Methods Placenta was divided into amniotic epithelium (AE), amniotic membrane (AM), chorionic membrane (CM), chorionic villi (CV), chorionic trophoblast without villi (CT-V), decidua (DC), and whole placenta (Pla). Cells isolated from each layer were subjected to analyses for their morphology, proliferation ability, surface markers, and multi-lineage differentiation potential. MSCs were isolated from all placental layers and their characteristics were compared. Findings Surface antigen phenotype, morphology, and differentiation characteristics of cells from all layers indicated that they exhibited properties of MSCs. MSCs from different placental layers had different proliferation rates and differentiation potentials. MSCs from CM, CT-V, CV, and DC had better population doubling time and multi-lineage differentiation potentials compared to those from other layers. Conclusions Our results indicate that MSCs with different characteristics can be isolated from all layers of term placenta. These finding suggest that it is necessary to appropriately select MSCs from different placental layers for successful and consistent outcomes in clinical applications. PMID:28225815

Low cost sol-gel derived SiC-SiO2 nanocomposite as anti reflection layer for enhanced performance of crystalline silicon solar cells

NASA Astrophysics Data System (ADS)

Jannat, Azmira; Lee, Woojin; Akhtar, M. Shaheer; Li, Zhen Yu; Yang, O.-Bong

2016-04-01

This paper describes the preparation, characterizations and the antireflection (AR) coating application in crystalline silicon solar cells of sol-gel derived SiC-SiO2 nanocomposite. The prepared SiC-SiO2 nanocomposite was effectively applied as AR layer on p-type Si-wafer via two step processes, where the sol-gel of precursor solution was first coated on p-type Si-wafer using spin coating at 2000 rpm and then subjected to annealing at 450 °C for 1 h. The crystalline, and structural observations revealed the existence of SiC and SiO2 phases, which noticeably confirmed the formation of SiC-SiO2 nanocomposite. The SiC-SiO2 layer on Si solar cells was found to be an excellent AR coating, exhibiting the low reflectance of 7.08% at wavelengths ranging from 400 to 1000 nm. The fabricated crystalline Si solar cell with SiC-SiO2 nanocomposite AR coating showed comparable power conversion efficiency of 16.99% to the conventional SixNx AR coated Si solar cell. New and effective sol-gel derived SiC-SiO2 AR layer would offer a promising technique to produce high performance Si solar cells with low-cost.

Enface Thickness Mapping and Reflectance Imaging of Retinal Layers in Diabetic Retinopathy.

PubMed

Francis, Andrew W; Wanek, Justin; Lim, Jennifer I; Shahidi, Mahnaz

2015-01-01

To present a method for image segmentation and generation of enface thickness maps and reflectance images of retinal layers in healthy and diabetic retinopathy (DR) subjects. High density spectral domain optical coherence tomography (SDOCT) images were acquired in 10 healthy and 4 DR subjects. Customized image analysis software identified 5 retinal cell layer interfaces and generated thickness maps and reflectance images of the total retina (TR), inner retina (IR), outer retina (OR), and the inner segment ellipsoid (ISe) band. Thickness maps in DR subjects were compared to those of healthy subjects by generating deviation maps which displayed retinal locations with thickness below, within, and above the normal 95% confidence interval. In healthy subjects, TR and IR thickness maps displayed the foveal depression and increased thickness in the parafoveal region. OR and ISe thickness maps showed increased thickness at the fovea, consistent with normal retinal anatomy. In DR subjects, thickening and thinning in localized regions were demonstrated on TR, IR, OR, and ISe thickness maps, corresponding to retinal edema and atrophy, respectively. TR and OR reflectance images showed reduced reflectivity in regions of increased thickness. Hard exudates appeared as hyper-reflective spots in IR reflectance images and casted shadows on the deeper OR and ISe reflectance images. The ISe reflectance image clearly showed the presence of focal laser scars. Enface thickness mapping and reflectance imaging of retinal layers is a potentially useful method for quantifying the spatial and axial extent of pathologies due to DR.

Enface Thickness Mapping and Reflectance Imaging of Retinal Layers in Diabetic Retinopathy

PubMed Central

Francis, Andrew W.; Wanek, Justin; Lim, Jennifer I.; Shahidi, Mahnaz

2015-01-01

Purpose To present a method for image segmentation and generation of enface thickness maps and reflectance images of retinal layers in healthy and diabetic retinopathy (DR) subjects. Methods High density spectral domain optical coherence tomography (SDOCT) images were acquired in 10 healthy and 4 DR subjects. Customized image analysis software identified 5 retinal cell layer interfaces and generated thickness maps and reflectance images of the total retina (TR), inner retina (IR), outer retina (OR), and the inner segment ellipsoid (ISe) band. Thickness maps in DR subjects were compared to those of healthy subjects by generating deviation maps which displayed retinal locations with thickness below, within, and above the normal 95% confidence interval. Results In healthy subjects, TR and IR thickness maps displayed the foveal depression and increased thickness in the parafoveal region. OR and ISe thickness maps showed increased thickness at the fovea, consistent with normal retinal anatomy. In DR subjects, thickening and thinning in localized regions were demonstrated on TR, IR, OR, and ISe thickness maps, corresponding to retinal edema and atrophy, respectively. TR and OR reflectance images showed reduced reflectivity in regions of increased thickness. Hard exudates appeared as hyper-reflective spots in IR reflectance images and casted shadows on the deeper OR and ISe reflectance images. The ISe reflectance image clearly showed the presence of focal laser scars. Conclusions Enface thickness mapping and reflectance imaging of retinal layers is a potentially useful method for quantifying the spatial and axial extent of pathologies due to DR. PMID:26699878

Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography.

PubMed

Higashide, Tomomi; Ohkubo, Shinji; Hangai, Masanori; Ito, Yasuki; Shimada, Noriaki; Ohno-Matsui, Kyoko; Terasaki, Hiroko; Sugiyama, Kazuhisa; Chew, Paul; Li, Kenneth K W; Yoshimura, Nagahisa

2016-01-01

To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects. The thickness of retinal layers {retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCLIPL), RNFL plus GCLIPL (ganglion cell complex, GCC), total retina, total retina minus GCC (outer retina)} were measured by macular scans (RS-3000, NIDEK) in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters) with or without magnification correction. For each layer thickness, a semipartial correlation (sr) was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index. Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13) regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33) and a negative sr with GCLIPL (sr2, 0.22 to 0.31), GCC (sr2, 0.03 to 0.17), total retina (sr2, 0.07 to 0.17) and outer retina (sr2, 0.16 to 0.29) in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction. The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction.

Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography

PubMed Central

Higashide, Tomomi; Ohkubo, Shinji; Hangai, Masanori; Ito, Yasuki; Shimada, Noriaki; Ohno-Matsui, Kyoko; Terasaki, Hiroko; Sugiyama, Kazuhisa; Chew, Paul; Li, Kenneth K. W.; Yoshimura, Nagahisa

2016-01-01

Purpose To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects. Methods The thickness of retinal layers {retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCLIPL), RNFL plus GCLIPL (ganglion cell complex, GCC), total retina, total retina minus GCC (outer retina)} were measured by macular scans (RS-3000, NIDEK) in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters) with or without magnification correction. For each layer thickness, a semipartial correlation (sr) was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index. Results Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13) regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33) and a negative sr with GCLIPL (sr2, 0.22 to 0.31), GCC (sr2, 0.03 to 0.17), total retina (sr2, 0.07 to 0.17) and outer retina (sr2, 0.16 to 0.29) in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction. Conclusions The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction. PMID:26814541

Histological assessments on the abnormalities of mouse epiphyseal chondrocytes with short term centrifugal loading.

PubMed

de Freitas, Paulo Henrique Luiz; Kojima, Taku; Ubaidus, Sobhan; Li, Minqi; Shang, Guangwei; Takagi, Ritsuo; Maeda, Takeyasu; Oda, Kimimitsu; Ozawa, Hidehiro; Amizuka, Norio

2007-08-01

We have examined the morphological changes in chondrocytes after exposure to experimental hypergravity. Tibial epiphyseal cartilages of 17-days-old mouse fetuses were exposed to centrifugation at 3G for 16 h mimicking hypergravitational environment (experimental group), or subjected to stationary cultures (control group). Centrifugation did not affect the sizes of epiphyseal cartilage, chondrocyte proliferation, type X collagen-positive hypertrophic zone, and the mRNA expressions of parathyroid hormone-related peptide and fibroblast growth factor receptor III. However, centrifuged chondrocytes showed abnormal morphology and aberrant spatial arrangements, resulting in disrupted chondrocytic columns. Through histochemical assessments, actin filaments were shown to distribute evenly along cell membranes of control proliferative chondrocytes, while chondrocytes subjected to centrifugal force developed a thicker layer of actin filaments. Transmission electron microscopic observations revealed spotty electron-dense materials underlying control chondrocytes' cell membranes, while experimental chondrocytes showed their thick layer. In the intracolumnar regions of the control cartilage, longitudinal electron-dense fibrils were associated with short cytoplasmic processes of normal chondrocytes, indicating assumed cell-tomatrix interactions. These extracellular fibrils were disrupted in the centrifuged samples. Summarizing, altered actin filaments associated with cell membranes, irregular cell shape and disappearance of intracolumnar extracellular fibrils suggest that hypergravity disturbs cell-to-matrix interactions in our cartilage model.

Asymmetry Analysis of Macular Inner Retinal Layers for Glaucoma Diagnosis: Swept-Source Optical Coherence Tomography Study

PubMed Central

Lee, Sang-Yoon; Lee, Eun Kyoung; Park, Ki Ho; Kim, Dong Myung

2016-01-01

Purpose To report an asymmetry analysis of macular inner retinal layers using swept-source optical coherence tomography (OCT) and to evaluate the utility for glaucoma diagnosis. Design Observational, cross-sectional study. Participants Seventy normal healthy subjects and 62 glaucoma patients. Methods Three-dimensional scans were acquired from 70 normal subjects and 62 open angle glaucoma patients by swept-source OCT. The thickness of the retinal nerve fiber layer, ganglion cell-inner plexiform layer (GCIPL), ganglion cell complex, and total retina were calculated within a 6.2×6.2 mm macular area divided into a 31×31 grid of 200×200 μm superpixels. For each of the corresponding superpixels, the thickness differences between the subject eyes and contra-lateral eyes and between the upper and lower macula halves of the subject eyes were determined. The negative differences were displayed on a gray-scale asymmetry map. Black superpixels were defined as thickness decreases over the cut-off values. Results The negative inter-ocular and inter-hemisphere differences in GCIPL thickness (mean ± standard deviation) were -2.78 ± 0.97 μm and -3.43 ± 0.71 μm in the normal group and -4.26 ± 2.23 μm and -4.88 ± 1.46 μm in the glaucoma group. The overall extent of the four layers’ thickness decrease was larger in the glaucoma group than in the normal group (all Ps<0.05). The numbers of black superpixels on all of the asymmetry maps were larger in the glaucoma group than in the normal group (all Ps<0.05). The area under receiver operating characteristic curves of average negative thickness differences in macular inner layers for glaucoma diagnosis ranged from 0.748 to 0.894. Conclusions The asymmetry analysis of macular inner retinal layers showed significant differences between the normal and glaucoma groups. The diagnostic performance of the asymmetry analysis was comparable to that of previous methods. These findings suggest that the asymmetry analysis can be a potential ancillary diagnostic tool. PMID:27764166

Panoramic view of human corneal endothelial cell layer observed by a prototype slit-scanning wide-field contact specular microscope.

PubMed

Tanaka, Hiroshi; Okumura, Naoki; Koizumi, Noriko; Sotozono, Chie; Sumii, Yasuhiro; Kinoshita, Shigeru

2017-05-01

To observe the most peripheral region of the corneal endothelial cell (CEC) layer as long as optically recordable by use of a prototype slit-scanning wide-field contact specular microscope and produce a panoramic image to evaluate the variation of CEC density with ageing. Observational case series study. This study involved 15 eyes of 15 normal healthy subjects divided into three groups according to age: A (20-40 years), B (41-60 years) and C (>60 years). The corneal endothelial layer of each eye was recorded in a horizontal direction, from nasal to temporal, with a slit-scanning wide-field contact specular microscope (Konan) and endothelial cell density (ECD) in three specific regions (central, mid-peripheral, and peripheral) was automatically calculated via built-in analysis software. Corneal endothelial images from near the surgical limbus to limbus in all eyes were clearly recorded and panoramic images were made by combining still images. ECD in groups A, B and C were 2809±186, 2717±91 and 2580±129 cells/mm 2 at the centre, 2902±242, 2772±97 and 2604±187 cells/mm 2 at the mid-periphery and 2893±308, 2691±99 and 2533±112 cells/mm 2 at the periphery. Significance differences in ECD was found between groups A and C in all regions and groups between B and C at mid-peripheral region. A prototype slit-scanning wide-field contact specular microscope enabled us to record the endothelial layer from the surgical limbus to limbus of the cornea and compare specific areas among subjects, and showed that ECD in each region of the cornea decreases with ageing. UMIN000021264, Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Early detection of macular and peripapillary changes with spectralis optical coherence tomography in patients with prediabetes.

PubMed

Şahin, Muhammed; Şahin, Alparslan; Kılınç, Faruk; Karaalp, Ümit; Yüksel, Harun; Özkurt, Zeynep Gürsel; Türkcü, Fatih Mehmet; Çaça, İhsan

2018-02-01

To compare the retina ganglion cell complex (GCC) layer and peripapillary nerve fibre layer thickness (pRNFL) in patients with prediabetes and healthy subjects analysed by spectral domain optical coherence tomography (SD-OCT). This cross-sectional and comparative study included prediabetic patients and healthy subjects. All participants underwent SD-OCT measurement of pRNFL thickness, and GCC thickness. A total of 30 eyes of the 30 patients with prediabetes and 30 eyes of 30 controls were included. The overall calculated pRNFL thicknesses were similar between the prediabetic and control subjects. The GCC thickness was significantly lower in all quadrants of the inner macula, and outer nasal quadrant in the prediabetes group when compared to the control group. Our study demonstrated that inner macular GCC thickness was significantly thinner in prediabetic subjects. As a result neurodegeneration may play role in the thinning of GCC.

New concepts of histological changes in experimental augmentation cystoplasty: insights into the development of neoplastic transformation at the enterovesical and gastrovesical anastomosis.

PubMed

Gitlin, J S; Wu, X R; Sun, T T; Ritchey, M L; Shapiro, E

1999-09-01

To our knowledge the pathogenesis of malignancy associated with ileal cystoplasty, ureterosigmoidostomy and ileal conduits is currently unknown. To gain further insights into the mechanism of neoplastic transformation we studied histological changes in a canine augmentation cystoplasty model. Enterocystoplasty and gastrocystoplasty were performed using a 5 to 7 cm. patch of ileum in 8 dogs and gastric antrum in 6. Specimens were harvested 4 months postoperatively. Representative 3 microm sections of the enterovesical and gastrovesical junctions were stained with hematoxylin and eosin. Uroplakin expression was assessed using an indirect peroxidase method subjected to double staining with alcian blue and periodic acid-Schiffreagent. The bladder portion of the augmentation cystoplasty had 3 to 4 stratified cell layers covered with a distinctive umbrella cell layer. Strong uroplakin staining was visible in all cell layers except the basal layer. At the enterovesical and gastrovesical junctions 6 to 10 layers of hyperplastic, urothelial appearing cells covered the glandular epithelium of the ileal and gastric segments. These cells expressed uroplakins. At this junction zone there was a marked decrease of underlying enteric glands, which had atrophied in proportion to the degree of urothelial hyperplasia. Double staining of uroplakin stained sections with alcian blue and periodic acid-Schiff reagent revealed mucosubstances in hyperplastic urothelial cells covering the enteral segments, indicating that the cells co-expressed uroplakins and mucins. Histological changes in this experimental canine model of augmentation cystoplasty indicated that the overgrowth of hyperplastic transitional epithelium develops at the enterovesical and gastrovesical junctions. These cells express not only uroplakins, but also mucosubstances. Our results suggest that the migrated hyperplastic urothelial cells have undergone changes characteristic of the enteric and gastric epithelium, which may have important implications in the pathogenesis of malignancy in bladder augmentations.

Glaucoma Diagnostic Capability of Global and Regional Measurements of Isolated Ganglion Cell Layer and Inner Plexiform Layer.

PubMed

Chien, Jason L; Ghassibi, Mark P; Patthanathamrongkasem, Thipnapa; Abumasmah, Ramiz; Rosman, Michael S; Skaat, Alon; Tello, Celso; Liebmann, Jeffrey M; Ritch, Robert; Park, Sung Chul

2017-03-01

To compare glaucoma diagnostic capability of global/regional macular layer parameters in different-sized grids. Serial horizontal spectral-domain optical coherence tomography scans of macula were obtained. Automated macular grids with diameters of 3, 3.45, and 6 mm were used. For each grid, 10 parameters (total volume; average thicknesses in 9 regions) were obtained for 5 layers: macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), ganglion cell-inner plexiform layer (GCIPL; GCL+IPL), and ganglion cell complex (GCC; mRNFL+GCL+IPL). Sixty-nine normal eyes (69 subjects) and 87 glaucomatous eyes (87 patients) were included. For the total volume parameter, the area under the receiver operating characteristic curves (AUCs) in 6-mm grid were larger than the AUCs in 3- and 3.45-mm grids for GCL, GCC, GCIPL, and mRNFL (all P<0.020). For the average thickness parameters, the best AUC in 6-mm grid (T2 region for GCL, IPL, and GCIPL; I2 region for mRNFL and GCC) was greater than the best AUC in 3-mm grid for GCL, GCC, and mRNFL (P<0.045). The AUC of GCL volume (0.920) was similar to those of GCC (0.920) and GCIPL (0.909) volume. The AUC of GCL T2 region thickness (0.942) was similar to those of GCC I2 region (0.942) and GCIPL T2 region (0.934) thickness. Isolated macular GCL appears to be as good as GCC and GCIPL in glaucoma diagnosis, while IPL does not. Larger macular grids may be better at detecting glaucoma. Each layer has a characteristic region with the best glaucoma diagnostic capability.

Method for passivating crystal silicon surfaces

DOEpatents

Wang, Qi [Littleton, CO; Wang, Tihu [Littleton, CO; Page, Matthew R [Littleton, CO; Yan, Yanfa [Littleton, CO

2009-12-08

In a method of making a c-Si-based cell or a .mu.c-Si-based cell, the improvement of increasing the minority charge carrier's lifetime, comprising: a) placing a c-Si or polysilicon wafer into CVD reaction chamber under a low vacuum condition and subjecting the substrate of the wafer to heating; and b) passing mixing gases comprising NH.sub.3/H.sub.2 through the reaction chamber at a low vacuum pressure for a sufficient time and at a sufficient flow rate to enable growth of an a-Si:H layer sufficient to increase the lifetime of the c-Si or polysilicon cell beyond that of the growth of an a-Si:H layer without treatment of the wafer with NH.sub.3/H.sub.2.

Reliability and efficacy of organic passivation for polycrystalline silicon solar cells at room temperature

NASA Astrophysics Data System (ADS)

Shinde, Onkar S.; Funde, Adinath M.; Jadkar, Sandesh R.; Dusane, Rajiv O.; Dhere, Neelkanth G.; Ghaisas, Subhash V.

2016-09-01

Oleylamine is used as a passivating layer instead of commercial high temperature SiNx. Oleylamine coating applied on the n-type emitter side with p-type base polycrystalline silicon solar cells at room temperature using a simple spin coating method. It has been observed that there is 16% increase in efficiency after Oleylamine coating. Further, the solar cell was subjected to standard characterization namely current-voltage measurement for electrical parameters and Fourier transform infrared spectroscopy to understand the interaction of emitter surface and passivating Oleylamine. However, the passivation layer is not stable due to the reaction between Oleylamine and ambient air content such as humidity and carbon dioxide. This degradation can be prevented with suitable overcoating.

Alterations in a Unique Class of Cortical Chandelier Cell Axon Cartridges in Schizophrenia.

PubMed

Rocco, Brad R; DeDionisio, Adam M; Lewis, David A; Fish, Kenneth N

2017-07-01

The axons of chandelier cells (ChCs) target the axon initial segment of pyramidal neurons, forming an array of boutons termed a cartridge. In schizophrenia, the density of cartridges detectable by gamma-aminobutyric acid (GABA) membrane transporter 1 immunoreactivity is lower, whereas the density of axon initial segments detectable by immunoreactivity for the α2 subunit of the GABA A receptor is higher in layers 2/superficial 3 of the prefrontal cortex. These findings were interpreted as compensatory responses to lower GABA levels in ChCs. However, we recently found that in schizophrenia, ChC cartridge boutons contain normal levels of the 67 kDa isoform of glutamic acid decarboxylase (GAD67) protein, the enzyme responsible for GABA synthesis in these boutons. To understand these findings we quantified the densities of ChC cartridges immunoreactive for vesicular GABA transporter (vGAT+), which is present in all cartridge boutons, and the subset of cartridges that contain calbindin (CB+). Prefrontal cortex tissue sections from 20 matched pairs of schizophrenia and unaffected comparison subjects were immunolabeled for vGAT, GAD67, and CB. The mean density of vGAT+/CB+ cartridges was 2.7-fold higher, exclusively in layer 2 of schizophrenia subjects, whereas the density of vGAT+/CB- cartridges did not differ between subject groups. Neither vGAT, CB, or GAD67 protein levels per ChC bouton nor the number of boutons per cartridge differed between subject groups. Our findings of a greater density of CB+ ChC cartridges in prefrontal cortex layer 2 from schizophrenia subjects suggests that the normal developmental pruning of these cartridges is blunted in the illness. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Short-term environmental enrichment exposure induces proliferation and maturation of doublecortin-positive cells in the prefrontal cortex

PubMed Central

Fan, Chunling; Zhang, Mengqi; Shang, Lei; Cynthia, Ngobe Akume; Li, Zhi; Yang, Zhenyu; Chen, Dan; Huang, Jufang; Xiong, Kun

2014-01-01

Previous studies have demonstrated that doublecortin-positive immature neurons exist predominantly in the superficial layer of the cerebral cortex of adult mammals such as guinea pigs, and these neurons exhibit very weak properties of self-proliferation during adulthood under physiological conditions. To verify whether environmental enrichment has an impact on the proliferation and maturation of these immature neurons in the prefrontal cortex of adult guinea pigs, healthy adult guinea pigs were subjected to short-term environmental enrichment. Animals were allowed to play with various cognitive and physical stimulating objects over a period of 2 weeks, twice per day, for 60 minutes each. Immunofluorescence staining results indicated that the number of doublecortin-positive cells in layer II of the prefrontal cortex was significantly increased after short-term environmental enrichment exposure. In addition, these doublecortin-positive cells co-expressed 5-bromo-2-deoxyuridine (a marker of cell proliferation), c-Fos (a marker of cell viability) and NeuN (a marker of mature neurons). Experimental findings showed that short-term environmental enrichment can induce proliferation, activation and maturation of doublecortin-positive cells in layer II of the prefrontal cortex of adult guinea pigs. PMID:25206818

Exogenous Hydrogen Peroxide Contributes to Heme Oxygenase-1 Delaying Programmed Cell Death in Isolated Aleurone Layers of Rice Subjected to Drought Stress in a cGMP-Dependent Manner

PubMed Central

Wang, Guanghui; Xiao, Yu; Deng, Xiaojiang; Zhang, Heting; Li, Tingge; Chen, Huiping

2018-01-01

Hydrogen peroxide (H2O2) is a reactive oxygen species (ROS) that plays a dual role in plant cells. Here, we discovered that drought (20% polyethylene glycol-6000, PEG)-triggered decreases of HO-1 transcript expression and HO activity. However, exogenous H2O2 contributed toward the increase in HO-1 gene expression and activity of the enzyme under drought stress. Meanwhile, the HO-1 inducer hematin could mimic the effects of the H2O2 scavengers ascorbic acid (AsA) and dimethylthiourea (DMTU) and the H2O2 synthesis inhibitor diphenyleneiodonium (DPI) for scavenging or diminishing drought-induced endogenous H2O2. Conversely, the zinc protoporphyrin IX (ZnPPIX), an HO-1-specific inhibitor, reversed the effects of hematin. We further analyzed the endogenous H2O2 levels and HO-1 transcript expression levels of aleurone layers treated with AsA, DMTU, and DPI in the presence of exogenous H2O2 under drought stress, respectively. The results showed that in aleurone layers subjected to drought stress, when the endogenous H2O2 level was inhibited, the effect of exogenous H2O2 on the induction of HO-1 was enhanced. Furthermore, exogenous H2O2-activated HO-1 effectively enhanced amylase activity. Application of 8-bromoguanosine 3′,5′-cyclic guanosine monophosphate (8-Br-cGMP) (the membrane permeable cGMP analog) promoted the effect of exogenous H2O2-delayed PCD of aleurone layers in response to drought stress. More importantly, HO-1 delayed the programmed cell death (PCD) of aleurone layers by cooperating with nitric oxide (NO), and the delayed effect of NO on PCD was achieved via mediation by cGMP under drought stress. In short, in rice aleurone layers, exogenous H2O2 (as a signaling molecule) triggered HO-1 and delayed PCD via cGMP which possibly induced amylase activity under drought stress. In contrast, as a toxic by-product of cellular metabolism, the drought-generated H2O2 promoted cell death. PMID:29449858

Exogenous Hydrogen Peroxide Contributes to Heme Oxygenase-1 Delaying Programmed Cell Death in Isolated Aleurone Layers of Rice Subjected to Drought Stress in a cGMP-Dependent Manner.

PubMed

Wang, Guanghui; Xiao, Yu; Deng, Xiaojiang; Zhang, Heting; Li, Tingge; Chen, Huiping

2018-01-01

Hydrogen peroxide (H 2 O 2 ) is a reactive oxygen species (ROS) that plays a dual role in plant cells. Here, we discovered that drought (20% polyethylene glycol-6000, PEG)-triggered decreases of HO-1 transcript expression and HO activity. However, exogenous H 2 O 2 contributed toward the increase in HO-1 gene expression and activity of the enzyme under drought stress. Meanwhile, the HO-1 inducer hematin could mimic the effects of the H 2 O 2 scavengers ascorbic acid (AsA) and dimethylthiourea (DMTU) and the H 2 O 2 synthesis inhibitor diphenyleneiodonium (DPI) for scavenging or diminishing drought-induced endogenous H 2 O 2 . Conversely, the zinc protoporphyrin IX (ZnPPIX), an HO-1-specific inhibitor, reversed the effects of hematin. We further analyzed the endogenous H 2 O 2 levels and HO-1 transcript expression levels of aleurone layers treated with AsA, DMTU, and DPI in the presence of exogenous H 2 O 2 under drought stress, respectively. The results showed that in aleurone layers subjected to drought stress, when the endogenous H 2 O 2 level was inhibited, the effect of exogenous H 2 O 2 on the induction of HO-1 was enhanced. Furthermore, exogenous H 2 O 2 -activated HO-1 effectively enhanced amylase activity. Application of 8-bromoguanosine 3',5'-cyclic guanosine monophosphate (8-Br-cGMP) (the membrane permeable cGMP analog) promoted the effect of exogenous H 2 O 2 -delayed PCD of aleurone layers in response to drought stress. More importantly, HO-1 delayed the programmed cell death (PCD) of aleurone layers by cooperating with nitric oxide (NO), and the delayed effect of NO on PCD was achieved via mediation by cGMP under drought stress. In short, in rice aleurone layers, exogenous H 2 O 2 (as a signaling molecule) triggered HO-1 and delayed PCD via cGMP which possibly induced amylase activity under drought stress. In contrast, as a toxic by-product of cellular metabolism, the drought-generated H 2 O 2 promoted cell death.

Spectroellipsometric, AFM and XPS probing of stainless steel surfaces subjected to biological influences

NASA Astrophysics Data System (ADS)

Vinnichenko, M.; Chevolleau, Th; Pham, M. T.; Poperenko, L.; Maitz, M. F.

2002-11-01

Surface modification of austenitic stainless steel (SS) 316L after incubation in growing cell cultures and cell-free media as control has been studied. The following treatments were applied: mouse fibrosarcoma cells L929 for 3 and 7 days, polymorphonuclear neutrophils for 3 and 7 days and human osteosarcoma cells SAOS-2 for 7 and 14 days. Cells were enzymatically removed in all cases. The modified surfaces were probed in comparison with untreated ones by means of spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). XPS shows the appearance of the peak of bonded nitrogen at 400.5 eV characteristic for adsorbed proteins on the surface for each type of cells and for the cell-free medium. Migration of Ni in the adsorbed layer is observed in all cases for samples after the cell cultures. The protein layer thickness is ellipsometrically determined to be within 2.5-6.0 nm for all treated samples with parameterization of its optical constants in Cauchy approach. The study showed that for such biological treatments of the SS the protein layer adsorption is the dominating process in the first 2 weeks, which could play a role in the process of corrosion by complex forming properties with metal ions.

Single-Walled Carbon Nanotubes in Solar Cells.

PubMed

Jeon, Il; Matsuo, Yutaka; Maruyama, Shigeo

2018-01-22

Photovoltaics, more generally known as solar cells, are made from semiconducting materials that convert light into electricity. Solar cells have received much attention in recent years due to their promise as clean and efficient light-harvesting devices. Single-walled carbon nanotubes (SWNTs) could play a crucial role in these devices and have been the subject of much research, which continues to this day. SWNTs are known to outperform multi-walled carbon nanotubes (MWNTs) at low densities, because of the difference in their optical transmittance for the same current density, which is the most important parameter in comparing SWNTs and MWNTs. SWNT films show semiconducting features, which make SWNTs function as active or charge-transporting materials. This chapter, consisting of two sections, focuses on the use of SWNTs in solar cells. In the first section, we discuss SWNTs as a light harvester and charge transporter in the photoactive layer, which are reviewed chronologically to show the history of the research progress. In the second section, we discuss SWNTs as a transparent conductive layer outside of the photoactive layer, which is relatively more actively researched. This section introduces SWNT applications in silicon solar cells, organic solar cells, and perovskite solar cells each, from their prototypes to recent results. As we go along, the science and prospects of the application of solar cells will be discussed.

Continuous Attractor Network Model for Conjunctive Position-by-Velocity Tuning of Grid Cells

PubMed Central

Si, Bailu; Romani, Sandro; Tsodyks, Misha

2014-01-01

The spatial responses of many of the cells recorded in layer II of rodent medial entorhinal cortex (MEC) show a triangular grid pattern, which appears to provide an accurate population code for animal spatial position. In layer III, V and VI of the rat MEC, grid cells are also selective to head-direction and are modulated by the speed of the animal. Several putative mechanisms of grid-like maps were proposed, including attractor network dynamics, interactions with theta oscillations or single-unit mechanisms such as firing rate adaptation. In this paper, we present a new attractor network model that accounts for the conjunctive position-by-velocity selectivity of grid cells. Our network model is able to perform robust path integration even when the recurrent connections are subject to random perturbations. PMID:24743341

Laser surface treatment of porous ceramic substrate for application in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Mahmod, D. S. A.; Khan, A. A.; Munot, M. A.; Glandut, N.; Labbe, J. C.

2016-08-01

Laser has offered a large number of benefits for surface treatment of ceramics due to possibility of localized heating, very high heating/cooling rates and possibility of growth of structural configurations only produced under non-equilibrium high temperature conditions. The present work investigates oxidation of porous ZrB2-SiC sintered ceramic substrates through treatment by a 1072 ± 10 nm ytterbium fiber laser. A multi-layer structure is hence produced showing successively oxygen rich distinct layers. The porous bulk beneath these layers remained unaffected as this laser-formed oxide scale and protected the substrate from oxidation. A glassy SiO2 structure thus obtained on the surface of the substrate becomes subject of interest for further research, specifically for its utilization as solid protonic conductor in Solid Oxide Fuel Cells (SOFCs).

Retina ganglion cell/inner plexiform layer and peripapillary nerve fiber layer thickness in patients with acromegaly.

PubMed

Şahin, Muhammed; Şahin, Alparslan; Kılınç, Faruk; Yüksel, Harun; Özkurt, Zeynep Gürsel; Türkcü, Fatih Mehmet; Pekkolay, Zafer; Soylu, Hikmet; Çaça, İhsan

2017-06-01

Increased secretion of growth hormone and insulin-like growth factor-1 in acromegaly has various effects on multiple organs. However, the ocular effects of acromegaly have yet to be investigated in detail. The aim of the present study was to compare retina ganglion cell/inner plexiform layer (GCIPL) and peripapillary nerve fiber layer thickness (pRNFL) between patients with acromegaly and healthy control subjects using spectral domain optical coherence tomography (SD-OCT). This cross-sectional, comparative study included 18 patients with acromegaly and 20 control subjects. All participants underwent SD-OCT to measure pRNFL (in the seven peripapillary areas), GCIPL (in the nine ETDRS areas), and central macular thickness (CMT). Visual field (VF) examinations were performed using a Humphrey field analyzer in acromegalic patients. Measurements were compared between patients with acromegaly and control subjects. A total of 33 eyes of 18 patients with acromegaly and 40 eyes of 20 control subjects met the inclusion criteria of the present study. The overall calculated average pRNFL thickness was significantly lower in patients with acromegaly than in control subjects (P = 0.01), with pRNFL thickness significantly lower in the temporal superior and temporal inferior quadrants. Contrary to our expectations, pRNFL thickness in the nasal quadrant was similar between acromegalic and control subjects. The mean overall pRNFL thickness and superonasal, nasal, inferonasal, and inferotemporal quadrant pRNFL thicknesses were found to correlate with the mean deviation (MD) according to Spearman's correlation. However, other quadrants were not correlated with VF sensitivity. No significant difference in CMT values was observed (P = 0.6). GCIPL thickness was significantly lower in all quadrants of the inner and outer macula, except for central and inferior outer quadrants, in the acromegaly group than that in the control group (P < 0.05). GCIPL thicknesses of the inferior inner and outer macula quadrants were found to correlate with MD, whereas no correlation was observed between other quadrants and VF sensitivity. We demonstrated that GCIPL thickness decreased in patients with acromegaly compared with that in control subjects. However, the nasal quadrant pRNFL thickness was similar in acromegaly, in contrast to our expectations. SD-OCT may have utility in the assessment of the effects of acromegaly on retinal structures.

Electron Radiation Damage of (alga) As-gaas Solar Cells

NASA Technical Reports Server (NTRS)

Loo, R.; Kamath, G. S.; Knechtli, R.

1979-01-01

Solar cells (2 cm by 2 cm (AlGa) As-GaAs cells) were fabricated and then subjected to irradiation at normal incidence by electrons. The influence of junction depth and n-type buffer layer doping level on the cell's resistance to radiation damage was investigated. The study shows that (1) a 0.3 micrometer deep junction results in lower damage to the cells than does a 0.5 micrometer junction, and (2) lowering the n buffer layer doping density does not improve the radiation resistance of the cell. Rather, lowering the doping density decreases the solar cell's open circuit voltage. Some preliminary thermal annealing experiments in vacuum were performed on the (AlGa)As-GaAs solar cells damaged by 1-MeV electron irradiation. The results show that cell performance can be expected to partially recover at 200 C with more rapid and complete recovery occurring at higher temperature. For a 0.5hr anneal at 400 C, 90% of the initial power is recovered. The characteristics of the (AlGa)As-GaAs cells both before and after irradiation are described.

Advances and Promises of Layered Halide Hybrid Perovskite Semiconductors.

PubMed

Pedesseau, Laurent; Sapori, Daniel; Traore, Boubacar; Robles, Roberto; Fang, Hong-Hua; Loi, Maria Antonietta; Tsai, Hsinhan; Nie, Wanyi; Blancon, Jean-Christophe; Neukirch, Amanda; Tretiak, Sergei; Mohite, Aditya D; Katan, Claudine; Even, Jacky; Kepenekian, Mikaël

2016-11-22

Layered halide hybrid organic-inorganic perovskites (HOP) have been the subject of intense investigation before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells and revisited for light-emitting devices. In this review, we combine classical solid-state physics concepts with simulation tools based on density functional theory to overview the main features of the optoelectronic properties of layered HOP. A detailed comparison between layered and 3D HOP is performed to highlight differences and similarities. In the same way as the cubic phase was established for 3D HOP, here we introduce the tetragonal phase with D 4h symmetry as the reference phase for 2D monolayered HOP. It allows for detailed analysis of the spin-orbit coupling effects and structural transitions with corresponding electronic band folding. We further investigate the effects of octahedral tilting on the band gap, loss of inversion symmetry and possible Rashba effect, quantum confinement, and dielectric confinement related to the organic barrier, up to excitonic properties. Altogether, this paper aims to provide an interpretive and predictive framework for 3D and 2D layered HOP optoelectronic properties.

Adjustment of Conduction Band Edge of Compact TiO2 Layer in Perovskite Solar Cells Through TiCl4 Treatment.

PubMed

Murakami, Takurou N; Miyadera, Tetsuhiko; Funaki, Takashi; Cojocaru, Ludmila; Kazaoui, Said; Chikamatsu, Masayuki; Segawa, Hiroshi

2017-10-25

Perovskite solar cells (PSCs) without a mesoporous TiO 2 layer, that is, planar-type PSCs exhibit poorer cell performance as compared to PSCs with a porous TiO 2 layer, owing to inefficient electron transfer from the perovskite layer to the compact TiO 2 layer in the former case. The matching of the conduction band levels of perovskite and the compact TiO 2 layer is thus essential for enhancing PSC performance. In this study, we demonstrate the shifting of the conduction band edge (CBE) of the compact TiO 2 layer through a TiCl 4 treatment, with the aim of improving PSC performance. The CBE of the compact TiO 2 layer was shifted to a higher level through the TiCl 4 treatment and then shifted in the opposite direction, that is, to a lower level, through a subsequent heat treatment. These shifts in the CBE were reflected in the PSC performance. The TiCl 4 -treated PSC showed an increase in the open-circuit voltage of more than 150 mV, as well as a decrease of 100 mV after being heated at 450 °C. On the other hand, the short-circuit current decreased after the treatment but increased after heating at temperatures higher than 300 °C. The treated PSC subjected to subsequent heating at 300 °C exhibited the best performance, with the power conversion efficiency of the PSC being 17% under optimized conditions.

Evaluation of the Ganglion Cell Complex and Retinal Nerve Fiber Layer in Low, Moderate, and High Myopia: A Study by RTVue Spectral Domain Optical Coherence Tomography.

PubMed

Sezgin Akcay, Betul Ilkay; Gunay, Betul Onal; Kardes, Esra; Unlu, Cihan; Ergin, Ahmet

2017-01-01

To assess the effect of low, moderate, and high myopia on the thickness of the retinal nerve fiber layer (RNFL) and Ganglion cell complex (GCC) measured by Spectral Domain Optical Coherence Tomography (SD-OCT) in non-glaucomatous subjects. The subjects were divided into three groups: low (n = 81, 35.6%), moderate (n = 79, 34.8%), and highly myopic eyes (n = 67, 29.5%). The RNFL thickness profile, including the average, superior, nasal, inferior, and temporal quadrant and each of the eight directional thicknesses, was measured. GCC parameters, including the average, superior, and inferior values, the focal loss volume (FLV), and the global loss volume (GLV), were measured. The correlation between the OCT measurements and the axial length was evaluated. The average, superior, inferior, and nasal RNFL thicknesses of low and moderate myopic eyes were found to be significantly higher than those of highly myopic eyes. The temporal RNFL thicknesses were not different among the three groups. The average, superior, and inferior ganglion cell complex values of low and moderate myopic eyes were significantly higher than those of highly myopic eyes. The FLV and GLV of low and moderate myopic eyes were significantly higher than those of highly myopic eyes (p = 0.001 for all). In the moderate and high myopia groups, the average RNFL thickness and GCC thickness were both negatively correlated with the axial length. Highly myopic subjects tend to have thinner RNFL and GCC thicknesses than subjects with low and moderate myopia.

Diagnostic ability of macular ganglion cell inner plexiform layer measurements in glaucoma using swept source and spectral domain optical coherence tomography.

PubMed

Yang, Zhiyong; Tatham, Andrew J; Weinreb, Robert N; Medeiros, Felipe A; Liu, Ting; Zangwill, Linda M

2015-01-01

To evaluate the diagnostic ability of macular ganglion cell and inner plexiform layer measurements in glaucoma, obtained using swept source (SS) and spectral domain (SD) optical coherence tomography (OCT) and to compare to circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements. The study included 106 glaucomatous eyes of 80 subjects and 41 eyes of 22 healthy subjects from the Diagnostic Innovations in Glaucoma Study. Macular ganglion cell and inner plexiform layer (mGCIPL), macular ganglion cell complex (mGCC) and cpRNFL thickness were assessed using SS-OCT and SD-OCT, and area under the receiver operating characteristic curves (AUCs) were calculated to determine ability to differentiate glaucomatous and healthy eyes and between early glaucomatous and healthy eyes. Mean (± standard deviation) mGCIPL and mGCC thickness were thinner in both healthy and glaucomatous eyes using SS-OCT compared to using SD-OCT. Fixed and proportional biases were detected between SS-OCT and SD-OCT measures. Diagnostic accuracy (AUCs) for differentiating between healthy and glaucomatous eyes for average and sectoral mGCIPL was similar in SS-OCT (0.65 to 0.81) and SD-OCT (0.63 to 0.83). AUCs for average cpRNFL acquired using SS-OCT and SD-OCT tended to be higher (0.83 and 0.85, respectively) than for average mGCC (0.82 and 0.78, respectively), and mGCIPL (0.73 and 0.75, respectively) but these differences did not consistently reach statistical significance. Minimum SD-OCT mGCIPL and mGCC thickness (unavailable in SS-OCT) had the highest AUC (0.86) among macular measurements. Assessment of mGCIPL thickness using SS-OCT or SD-OCT is useful for detecting glaucomatous damage, but measurements are not interchangeable for patient management decisions. Diagnostic accuracies of mGCIPL and mGCC from both SS-OCT and SD-OCT were similar to that of cpRNFL for glaucoma detection.

Diagnostic Ability of Macular Ganglion Cell Inner Plexiform Layer Measurements in Glaucoma Using Swept Source and Spectral Domain Optical Coherence Tomography

PubMed Central

Yang, Zhiyong; Tatham, Andrew J.; Weinreb, Robert N.; Medeiros, Felipe A.; Liu, Ting; Zangwill, Linda M.

2015-01-01

Purpose To evaluate the diagnostic ability of macular ganglion cell and inner plexiform layer measurements in glaucoma, obtained using swept source (SS) and spectral domain (SD) optical coherence tomography (OCT) and to compare to circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements. Methods The study included 106 glaucomatous eyes of 80 subjects and 41 eyes of 22 healthy subjects from the Diagnostic Innovations in Glaucoma Study. Macular ganglion cell and inner plexiform layer (mGCIPL), macular ganglion cell complex (mGCC) and cpRNFL thickness were assessed using SS-OCT and SD-OCT, and area under the receiver operating characteristic curves (AUCs) were calculated to determine ability to differentiate glaucomatous and healthy eyes and between early glaucomatous and healthy eyes. Results Mean (± standard deviation) mGCIPL and mGCC thickness were thinner in both healthy and glaucomatous eyes using SS-OCT compared to using SD-OCT. Fixed and proportional biases were detected between SS-OCT and SD-OCT measures. Diagnostic accuracy (AUCs) for differentiating between healthy and glaucomatous eyes for average and sectoral mGCIPL was similar in SS-OCT (0.65 to 0.81) and SD-OCT (0.63 to 0.83). AUCs for average cpRNFL acquired using SS-OCT and SD-OCT tended to be higher (0.83 and 0.85, respectively) than for average mGCC (0.82 and 0.78, respectively), and mGCIPL (0.73 and 0.75, respectively) but these differences did not consistently reach statistical significance. Minimum SD-OCT mGCIPL and mGCC thickness (unavailable in SS-OCT) had the highest AUC (0.86) among macular measurements. Conclusion Assessment of mGCIPL thickness using SS-OCT or SD-OCT is useful for detecting glaucomatous damage, but measurements are not interchangeable for patient management decisions. Diagnostic accuracies of mGCIPL and mGCC from both SS-OCT and SD-OCT were similar to that of cpRNFL for glaucoma detection. PMID:25978420

Raman microspectroscopic study of oral buccal mucosa

NASA Astrophysics Data System (ADS)

Behl, Isha; Mamgain, Hitesh; Deshmukh, Atul; Kukreja, Lekha; Hole, Arti R.; Krishna, C. Murali

2014-03-01

Oral cancer is the most common cancer among Indian males, with 5-year- survival-rates of less than 50%. Efficacy of Raman spectroscopic methods in non-invasive and objective diagnosis of oral cancers and confounding factors has already been demonstrated. The present Raman microspectroscopic study was undertaken for in-depth and site-specific analysis of normal and tumor tissues. 10 normal and 10 tumors unstained sections from 20 tissues were accrued. Raman data of 160 x 60 μm and 140 x 140 μm in normal and tumor sections, respectively, were acquired using WITec alpha 300R equipped with 532 nm laser, 50X objective and 600 gr/mm grating. Spectral data were corrected for CCDresponse, background. First-derivitized and vector-normalized data were then subjected to K-mean cluster analysis to generate Raman maps and correlated with their respective histopathology. In normal sections, stratification among epithelial layers i.e. basal, intermediate, superficial was observed. Tumor, stromal and inflammatory regions were identified in case of tumor section. Extracted spectra of the pathologically annotated regions were subjected to Principal component analysis. Findings suggest that all three layers of normal epithelium can be differentiated against tumor cells. In epithelium, basal and superficial layers can be separated while intermediate layer show misclassifications. In tumors, discrimination of inflammatory regions from tumor cells and tumor-stroma regions were observed. Finding of the study indicate Raman mapping can lead to molecular level insights of normal and pathological states.

The Effects of Diabetic Retinopathy and Pan-Retinal Photocoagulation on Photoreceptor Cell Function as Assessed by Dark Adaptometry

PubMed Central

Bavinger, J. Clay; Dunbar, Grace E.; Stem, Maxwell S.; Blachley, Taylor S.; Kwark, Leon; Farsiu, Sina; Jackson, Gregory R.; Gardner, Thomas W.

2016-01-01

Purpose The pathophysiology of vision loss in persons with diabetic retinopathy (DR) is complex and incompletely defined. We hypothesized that retinal pigment epithelium (RPE) and rod and cone photoreceptor dysfunction, as measured by dark adaptometry, would increase with severity of DR, and that pan-retinal photocoagulation (PRP) would exacerbate this dysfunction. Methods Dark adaptation (DA) was measured in subjects with diabetes mellitus and healthy controls. Dark adaptation was measured at 5° superior to the fovea following a flash bleach, and the data were analyzed to yield cone and rod sensitivity curves. Retinal layer thicknesses were quantified using spectral-domain optical coherence tomography (OCT). Results The sample consisted of 23 controls and 73 diabetic subjects. Subjects with moderate nonproliferative diabetic retinopathy (NPDR) exhibited significant impairment of rod recovery rate compared with control subjects (P = 0.04). Cone sensitivity was impaired in subjects with proliferative diabetic retinopathy (PDR) (type 1 diabetes mellitus [T1DM]: P = 0.0047; type 2 diabetes mellitus [T2DM]: P < 0.001). Subjects with untreated PDR compared with subjects treated with PRP exhibited similar rod recovery rates and cone sensitivities. Thinner RPE as assessed by OCT was associated with slower rod recovery and lower cone sensitivity, and thinner photoreceptor inner segment/outer segment layer was associated with lower cone sensitivity. Conclusions The results suggest that RPE and photoreceptor cell dysfunction, as assessed by cone sensitivity level and rod- and RPE-mediated dark adaptation, progresses with worsening DR, and rod recovery dysfunction occurs earlier than cone dysfunction. Function was preserved following PRP. The findings suggest multiple defects in retinoid function and provide potential points to improve visual function in persons with PDR. PMID:26803796

Titania nanotubes with adjustable dimensions for drug reservoir sites and enhanced cell adhesion.

PubMed

Çalışkan, Nazlı; Bayram, Cem; Erdal, Ebru; Karahaliloğlu, Zeynep; Denkbaş, Emir Baki

2014-02-01

This study aims to generate a bactericidal agent releasing surface via nanotube layer on titanium metal and to investigate how aspect ratio of nanotubes affects drug elution time and cell proliferation. Titania nanotube layers were generated on metal surfaces by anodic oxidation at various voltage and time parameters. Gentamicin loading was carried out via simple pipetting and the samples were tested against S. aureus for the efficacy of the applied modification. Drug releasing time and cell proliferation were also tested in vitro. Titania nanotube layers with varying diameters and lengths were prepared after anodization and anodizing duration was found as the most effective parameter for amount of loaded drug and drug releasing time. Drug elution lasted up to 4 days after anodizing for 80 min of the samples, whereas release completed in 24 h when the samples were anodized for 20 min. All processed samples had bactericidal properties against S. aureus organism except unmodified titanium, which was also subjected to drug incorporation step. The anodization also enhanced water wettability and cell adhesion results. Anodic oxidation is an effective surface modification to enhance tissue-implant interactions and also resultant titania layer can act as a drug reservoir for the release of bactericidal agents. The use of implants as local drug eluting devices is promising but further in vivo testing is required. Copyright © 2013 Elsevier B.V. All rights reserved.

Peripheral blood CD34+KDR+ endothelial progenitor cells are determinants of subclinical atherosclerosis in a middle-aged general population.

PubMed

Fadini, Gian Paolo; Coracina, Anna; Baesso, Ilenia; Agostini, Carlo; Tiengo, Antonio; Avogaro, Angelo; de Kreutzenberg, Saula Vigili

2006-09-01

Disruption of the endothelial layer is the first step in the atherogenic process. Experimental studies have shown that endothelial progenitor cells (EPCs) are involved in endothelial homeostasis and repair. Conversely, EPC depletion has been demonstrated in the setting of established atherosclerotic diseases. With this background, we evaluated whether variations in the number of EPCs are associated with subclinical atherosclerosis in healthy subjects. Carotid intima-media thickness (IMT), high-sensitive C-reactive protein (hsCRP), levels of circulating EPCs, and cardiovascular risk were compared in 137 healthy subjects. Six subpopulations of progenitor cells were determined by flow cytometry on the basis of the surface expression of CD34, CD133, and KDR antigens: CD34(+), CD133(+), CD34(+)CD133(+), CD34(+)KDR(+), CD133(+)KDR(+), and CD34(+)CD133(+)KDR(+). Among different antigenic profiles of EPCs, only CD34(+)KDR(+) cells were significantly reduced in subjects with increased IMT. Specifically, CD34(+)KDR(+) cells were inversely correlated with IMT, even after adjustment for hsCRP and 10-year Framingham risk and independently of other cardiovascular parameters. Depletion of CD34(+)KDR(+) EPCs is an independent predictor of early subclinical atherosclerosis in healthy subjects and may provide additional information beyond classic risk factors and inflammatory markers.

Vitronectin Expression in the Airways of Subjects with Asthma and Chronic Obstructive Pulmonary Disease

PubMed Central

Salazar-Peláez, Lina M.; Abraham, Thomas; Herrera, Ana M.; Correa, Mario A.; Ortega, Jorge E.; Paré, Peter D.; Seow, Chun Y.

2015-01-01

Vitronectin, a multifunctional glycoprotein, is involved in coagulation, inhibition of the formation of the membrane attack complex (MAC), cell adhesion and migration, wound healing, and tissue remodeling. The primary cellular source of vitronectin is hepatocytes; it is not known whether resident cells of airways produce vitronectin, even though the glycoprotein has been found in exhaled breath condensate and bronchoalveolar lavage from healthy subjects and patients with interstitial lung disease. It is also not known whether vitronectin expression is altered in subjects with asthma and COPD. In this study, bronchial tissue from 7 asthmatic, 10 COPD and 14 control subjects was obtained at autopsy and analyzed by immunohistochemistry to determine the percent area of submucosal glands occupied by vitronectin. In a separate set of experiments, quantitative colocalization analysis was performed on tracheobronchial tissue sections obtained from donor lungs (6 asthmatics, 4 COPD and 7 controls). Vitronectin RNA and protein expressions in bronchial surface epithelium were examined in 12 subjects who undertook diagnostic bronchoscopy. Vitronectin was found in the tracheobronchial epithelium from asthmatic, COPD, and control subjects, although its expression was significantly lower in the asthmatic group. Colocalization analysis of 3D confocal images indicates that vitronectin is expressed in the glandular serous epithelial cells and in respiratory surface epithelial cells other than goblet cells. Expression of the 65-kDa vitronectin isoform was lower in bronchial surface epithelium from the diseased subjects. The cause for the decreased vitronectin expression in asthma is not clear, however, the reduced concentration of vitronectin in the epithelial/submucosal layer of airways may be linked to airway remodeling. PMID:25768308

Enhanced cell adhesion on severe peened-plasma nitrided 316L stainless steel

NASA Astrophysics Data System (ADS)

Jayalakshmi, M.; Bhat, Badekai Ramachandra; Bhat, K. Udaya

2018-04-01

Plasma nitriding is an effective technique to enhance the wear resistance of austenitic stainless steels. Recently, severe surface deformation techniques are extensively used prior to nitriding to enhance diffusion kinetics. In the present study, AISI 316L austenitic stainless steel is subjected to peening-nitriding duplex treatment and biocompatibility of treated surfaces is assessed through adhesion of the fibroblast cells. Three-fold increase in the surface microhardness is observed from the un-peened sample to the peened-nitrided sample; with severe peened sample showing intermediate hardness. Similar trend is observed in the number of the fibroblast cells attached to the sample surface. Spreading of some of the fibroblast cells is observed on the sample subjected to duplex treatment; while the other two samples showed only the spindle shaped fibroblasts. Combined influence of surface nanocrystallization and presence of nitride layer is responsible for the improved biocompatibility.

Investigating Phase-Change-Induced Flow in Gas Diffusion Layers in Fuel Cells with X-ray Computed Tomography

DOE PAGES

Shum, Andrew D.; Parkinson, Dilworth Y.; Xiao, Xianghui; ...

2017-10-07

The performance of polymer-electrolyte fuel cells is heavily dependent on proper management of liquid water. One particular reason is that liquid water can collect in the gas diffusion layers (GDLs) blocking the reactant flow to the catalyst layer. This results in increased mass-transport losses. At higher temperatures, evaporation of water becomes a dominant water-removal mechanism and specifically phase-change-induced (PCI) flow is present due to thermal gradients. This study used synchrotron based micro X-ray computed tomography (CT) to visualize and quantify the water distribution within gas diffusion layers subject to a thermal gradient. Plotting saturation as a function of through-plane distancemore » quantitatively shows water redistribution, where water evaporates at hotter locations and condenses in colder locations. The morphology of the 2 GDLs on the micro-scale, as well as evaporating water clusters, are resolved, indicating that the GDL voids are slightly prolate, whereas water clusters are oblate. From the mean radii of water distributions and visual inspection, it is observed that larger water clusters evaporate faster than smaller ones.« less

How normal is the transparent cornea? Effects of aging on corneal morphology.

PubMed

Hillenaar, Toine; van Cleynenbreugel, Hugo; Remeijer, Lies

2012-02-01

To ascertain the effects of aging on corneal morphology and to illustrate the morphologic diversity of the different layers in the normal cornea as seen by in vivo confocal microscopy (IVCM). Observational cross-sectional study. A total of 150 healthy subjects, evenly distributed over 5 age categories, comprising 75 men and 75 women. Both transparent corneas (n = 300) of all subjects were examined in duplicate by white light IVCM (Confoscan 4, NIDEK Technologies, Albignasego, Padova, Italy). After reviewing the IVCM examinations for morphologic variations of the corneal layers, we selected the 8 most common features to illustrate the morphologic diversity. Subsequently, all 600 IVCM examinations were assessed for the presence of these features. We used binary logistic regression analyses to assess the age-relatedness of each feature. Age distribution of bright superficial epithelial cells, dendriform cells, alterations characteristic of epithelial basement membrane dystrophy (EBMD), tortuous stromal nerves, stromal microdots in the anterior stroma, folds in the posterior stroma, opacification of Descemet's membrane, and corneal guttae. Four features were found characteristic of the aging cornea: stromal microdots in the anterior stroma (P<0.0001), folds in the posterior stroma (P<0.0001), opacification of Descemet's membrane (P<0.0001), and corneal guttae (P<0.0001). Alterations characteristic of EBMD were found in 3% of all eyes and only detected in subjects aged ≥40 years, suggesting age-relatedness (P = 0.09). Other features, such as bright superficial epithelial cells (n = 38, 13%), dendriform cells (n = 42, 14%), and tortuous stromal nerves (n = 115, 38%), were age-independent. We also found a novel phenotype of corneal endothelium in 4 normal eyes of 2 subjects, which we coined "salt and pepper endothelium." We could not establish whether this novel phenotype represented a morphologic variant of normal endothelium, an early stage of a known corneal endothelial disorder, or a completely new disease entity. Knowledge of the common morphologic variations of the corneal layers and the effects of aging on corneal morphology as seen by IVCM increases our understanding of corneal degenerative disorders and is essential to detect corneal pathology. Our finding of a novel phenotype of corneal endothelium emphasizes the morphologic diversity of this optically transparent tissue. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Differential voltage analysis as a tool for analyzing inhomogeneous aging: A case study for LiFePO4|Graphite cylindrical cells

NASA Astrophysics Data System (ADS)

Lewerenz, Meinert; Marongiu, Andrea; Warnecke, Alexander; Sauer, Dirk Uwe

2017-11-01

In this work the differential voltage analysis (DVA) is evaluated for LiFePO4|Graphite cylindrical cells aged in calendaric and cyclic tests. The homogeneity of the active lithium distribution and the loss of anode active material (LAAM) are measured by the characteristic shape and peaks of the DVA. The results from this analysis exhibit an increasing homogeneity of the lithium-ion distribution during aging for all cells subjected to calendaric aging. At 60 °C, LAAM is found additionally and can be associated with the deposition of dissolved Fe from the cathode on the anode, where it finally leads to the clogging of pores. For cells aged under cyclic conditions, several phenomena are correlated to degradation, such as loss of active lithium and local LAAM for 100% DOD. Moreover, the deactivation of certain parts of anode and cathode due to a lithium-impermeable covering layer on top of the anode is observed for some cells. While the 100% DOD cycling is featured by a continuous LAAM, the LAAM due to deactivation by a covering layer of both electrodes starts suddenly. The homogeneity of the active lithium distribution within the cycled cells is successively reduced with deposited passivation layers and with LAAM that is lost locally at positions with lower external pressure on the electrode.

Differences in Optic Nerve Head, Retinal Nerve Fiber Layer, and Ganglion Cell Complex Parameters Between Caucasian and Chinese Subjects.

PubMed

Chansangpetch, Sunee; Huang, Guofu; Coh, Paul; Oldenburg, Catherine; Amoozgar, Behzad; He, Mingguang; Lin, Shan C

2018-04-01

To compare optic nerve head, peripapillary retinal nerve fiber layer (pRNFL), and ganglion cell complex (GCC) parameters between Caucasian and ethnic Chinese. Normal subjects above 40 years old and self-identified as being Caucasian and Chinese were recruited. They were evaluated with spectral-domain optical coherence tomography (RTVue-100). Parameters related to the optic nerve head, pRNFL, and GCC analysis protocols were acquired. Multivariable linear regression was performed adjusting for potential confounders. Data from 116 Caucasian and 130 Chinese subjects were available for analysis. Mean age of all participants was 66.72 (SD 10.82) years. There were statistically significant differences for disc area (DA), area cup-to-disc, vertical cup-to-disc, and cup volume (P=0.02, 0.004, 0.02, and 0.03, respectively), greater in Chinese. After adjusting for age, sex, axial length (AL), intraocular pressure (IOP), DA, and GCC thickness, Chinese subjects had significantly greater thickness in all pRNFL parameters (mean differences ranged between 4.29 and 9.93 μm; all P<0.001) except the nasal quadrant. GCC outcomes were also adjusted for DA and pRNFL; Caucasians had significantly higher average GCC and inferior GCC (mean difference 2.97 and 3.45 μm, respectively; P<0.01), whereas the Chinese group had significantly higher ganglion cell global loss volume (mean difference 2.47 %, P<0.001). This study suggests there is significantly greater pRNFL thickness in Chinese, which were independent of age, AL, IOP, and DA, and possibly greater GCC in Caucasians after adjustment for age, AL, IOP, DA, and pRNFL thickness.

Events associated with apoptotic effect of p-Coumaric acid in HCT-15 colon cancer cells

PubMed Central

Jaganathan, Saravana Kumar; Supriyanto, Eko; Mandal, Mahitosh

2013-01-01

AIM: To investigate the events associated with the apoptotic effect of p-Coumaric acid, one of the phenolic components of honey, in human colorectal carcinoma (HCT-15) cells. METHODS: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tertazolium-bromide assay was performed to determine the antiproliferative effect of p-Coumaric acid against colon cancer cells. Colony forming assay was conducted to quantify the colony inhibition in HCT 15 and HT 29 colon cancer cells after p-Coumaric acid treatment. Propidium Iodide staining of the HCT 15 cells using flow cytometry was done to study the changes in the cell cycle of treated cells. Identification of apoptosis was done using scanning electron microscope and photomicrograph evaluation of HCT 15 cells after exposing to p-Coumaric acid. Levels of reactive oxygen species (ROS) of HCT 15 cells exposed to p-Coumaric acid was evaluated using 2’, 7’-dichlorfluorescein-diacetate. Mitochondrial membrane potential of HCT-15 was assessed using rhodamine-123 with the help of flow cytometry. Lipid layer breaks associated with p-Coumaric acid treatment was quantified using the dye merocyanine 540. Apoptosis was confirmed and quantified using flow cytometric analysis of HCT 15 cells subjected to p-Coumaric acid treatment after staining with YO-PRO-1. RESULTS: Antiproliferative test showed p-Coumaric acid has an inhibitory effect on HCT 15 and HT 29 cells with an IC50 (concentration for 50% inhibition) value of 1400 and 1600 μmol/L respectively. Colony forming assay revealed the time-dependent inhibition of HCT 15 and HT 29 cells subjected to p-Coumaric acid treatment. Propidium iodide staining of treated HCT 15 cells showed increasing accumulation of apoptotic cells (37.45 ± 1.98 vs 1.07 ± 1.01) at sub-G1 phase of the cell cycle after p-Coumaric acid treatment. HCT-15 cells observed with photomicrograph and scanning electron microscope showed the signs of apoptosis like blebbing and shrinkage after p-Coumaric acid exposure. Evaluation of the lipid layer showed increasing lipid layer breaks was associated with the growth inhibition of p-Coumaric acid. A fall in mitochondrial membrane potential and increasing ROS generation was observed in the p-Coumaric acid treated cells. Further apoptosis evaluated by YO-PRO-1 staining also showed the time-dependent increase of apoptotic cells after treatment. CONCLUSION: These results depicted that p-Coumaric acid inhibited the growth of colon cancer cells by inducing apoptosis through ROS-mitochondrial pathway. PMID:24282361

Age-related increase of sIAHP in prefrontal pyramidal cells of monkeys: relationship to cognition

PubMed Central

Luebke, Jennifer I.; Amatrudo, Joseph M.

2010-01-01

Reduced excitability, due to an increase in the slow afterhyperpolarization (and its underlying current sIAHP), occurs in CA1 pyramidal cells in aged cognitively-impaired, but not cognitively-unimpaired, rodents. We sought to determine whether similar age-related changes in the sIAHP occur in pyramidal cells in the rhesus monkey dorsolateral prefrontal cortex (dlPFC). Whole-cell patch-clamp recordings were obtained from layer 3 (L3) and layer 5 (L5) pyramidal cells in dlPFC slices prepared from young (9.6 ± 0.7 years old) and aged (22.3 ± 0.7 years old) behaviorally characterized subjects. The amplitude of the sIAHP was significantly greater in L3 (but not L5) cells from aged-impaired compared to both aged-unimpaired and young monkeys, which did not differ. Aged L3, but not L5, cells exhibited significantly increased action potential firing rates, but there was no relationship between sIAHP and firing rate. Thus, in monkey dlPFC L3 cells, an increase in sIAHP is associated with age-related cognitive decline; however, this increase is not associated with a reduction in excitability. PMID:20727620

Age-Related Alterations in the Retinal Microvasculature, Microcirculation, and Microstructure.

PubMed

Wei, Yantao; Jiang, Hong; Shi, Yingying; Qu, Dongyi; Gregori, Giovanni; Zheng, Fang; Rundek, Tatjana; Wang, Jianhua

2017-07-01

To characterize age-related alterations in the retinal microcirculation, microvascular network, and microstructure in healthy subjects. Seventy-four healthy subjects aged from 18 to 82 years were recruited and divided into four age groups (G1 with age <35 years, G2 with age 35 ∼ 49 years, G3 with age 50 ∼ 64 years, and G4 with age ≥65 years). Custom ultra-high resolution optical coherence tomography (UHR-OCT) was used to acquire six intraretinal layers of the macula. OCT angiography (OCTA) was used to image the retinal microvascular network. The retinal blood flow velocity (BFV) was measured using a Retinal Function Imager (RFI). Compared to G1, G2 had significant thinning of the retinal nerve fiber layer (RNFL) (P < 0.05), while G3 had thinning of the RNFL and ganglion cell and inner plexiform layer (GCIPL) (P < 0.05), in addition to thickening of the outer plexiform layer (OPL) and photoreceptor layer (PR) (P < 0.05). G4 had loss in retinal vessel density, thinning in RNFL and GCIPL, and decrease in venular BFV, in addition to thickening of the OPL and PR (P < 0.05). Age was negatively related to retinal vessel densities, the inner retinal layers, and venular BFV (P < 0.05). By contrast, age was positively related to OPL and PR (P < 0.05). During aging, decreases in retinal vessel density, inner retinal layer thickness, and venular BFV were evident and impacted each other as observed by simultaneous changes in multiple retinal components.

Potential application of CuSbS2 as the hole transport material in perovskite solar cell: A simulation study

NASA Astrophysics Data System (ADS)

Teimouri, R.; Mohammadpour, R.

2018-06-01

CH3 NH3 PbI3 (MAPbI3) thin film solar cells, which are reported at laboratory efficiency scale of nearly 22%, are the subject of much attention by energy researchers due to their low cost buildup, acceptable efficiency, high absorption coefficient and diffusion length. The main purpose of this research is to simulate the structure of thin film perovskite solar cells through numerical simulation of SCAPS based on the empirical data for different hole transport layers. After simulating the initial structure of FTO/TiO2/CH3NH3PbI3/Spiro-OMeTAD solar cell, the hole transport layer Spiro-OMeTAD thickness was optimized on a small scale using modeling. The researchers also sought to reduce the amount of this material and the cost of construction. Ultimately, an optimum thickness of 140 nm was obtained for this cell with efficiency of 22.88%. The effect of employing alternative inorganic hole transport layer was investigated as a substitute for Spiro-OMeTAD; Copper antimony sulphide (CuSbS2) was selected due to abundant and available material and high open circuit voltage of about 988 mV. Thickness variations were also performed on a MAPbI3/CuSbS2 solar cell. Finally, It has obtained that perovskite solar cell with 120 nm-thick of CuSbS2 has 23.14% conversion efficiency with acceptable VOC and JSC values.

Reduction in interface defect density in p-BaSi2/n-Si heterojunction solar cells by a modified pretreatment of the Si substrate

NASA Astrophysics Data System (ADS)

Yamashita, Yudai; Yachi, Suguru; Takabe, Ryota; Sato, Takuma; Emha Bayu, Miftahullatif; Toko, Kaoru; Suemasu, Takashi

2018-02-01

We have investigated defects that occurred at the interface of p-BaSi2/n-Si heterojunction solar cells that were fabricated by molecular beam epitaxy. X-ray diffraction measurements indicated that BaSi2 (a-axis-oriented) was subjected to in-plane compressive strain, which relaxed when the thickness of the p-BaSi2 layer exceeded 50 nm. Additionally, transmission electron microscopy revealed defects in the Si layer near steps that were present on the Si(111) substrate. Deep level transient spectroscopy revealed two different electron traps in the n-Si layer that were located at 0.33 eV (E1) and 0.19 eV (E2) below the conduction band edge. The densities of E1 and E2 levels in the region close to the heterointerface were approximately 1014 cm-3. The density of these electron traps decreased below the limits of detection following Si pretreatment to remove the oxide layers from the n-Si substrate, which involved heating the substrate to 800 °C for 30 min under ultrahigh vacuum while depositing a layer of Si (1 nm). The remaining traps in the n-Si layer were hole traps located at 0.65 eV (H1) and 0.38 eV (H2) above the valence band edge. Their densities were as low as 1010 cm-3. Following pretreatment, the current versus voltage characteristics of the p-BaSi2/n-Si solar cells under AM1.5 illumination were reproducible with conversion efficiencies beyond 5% when using a p-BaSi2 layer thickness of 100 nm. The origin of the H2 level is discussed.

Marine boundary layer cloud regimes and POC formation in an LES coupled to a bulk aerosol scheme

NASA Astrophysics Data System (ADS)

Berner, A. H.; Bretherton, C. S.; Wood, R.; Muhlbauer, A.

2013-07-01

A large-eddy simulation (LES) coupled to a new bulk aerosol scheme is used to study long-lived regimes of aerosol-boundary layer cloud-precipitation interaction and the development of pockets of open cells (POCs) in subtropical stratocumulus cloud layers. The aerosol scheme prognoses mass and number concentration of a single log-normal accumulation mode with surface and entrainment sources, evolving subject to processing of activated aerosol and scavenging of dry aerosol by cloud and rain. The LES with the aerosol scheme is applied to a range of steadily-forced simulations idealized from a well-observed POC case. The long-term system evolution is explored with extended two-dimensional simulations of up to 20 days, mostly with diurnally-averaged insolation. One three-dimensional two-day simulation confirms the initial development of the corresponding two-dimensional case. With weak mean subsidence, an initially aerosol-rich mixed layer deepens, the capping stratocumulus cloud slowly thickens and increasingly depletes aerosol via precipitation accretion, then the boundary layer transitions within a few hours into an open-cell regime with scattered precipitating cumuli, in which entrainment is much weaker. The inversion slowly collapses for several days until the cumulus clouds are too shallow to efficiently precipitate. Inversion cloud then reforms and radiatively drives renewed entrainment, allowing the boundary layer to deepen and become more aerosol-rich, until the stratocumulus layer thickens enough to undergo another cycle of open-cell formation. If mean subsidence is stronger, the stratocumulus never thickens enough to initiate drizzle and settles into a steady state. With lower initial aerosol concentrations, this system quickly transitions into open cells, collapses, and redevelops into a different steady state with a shallow, optically thin cloud layer. In these steady states, interstitial scavenging by cloud droplets is the main sink of aerosol number. The system is described in a reduced two-dimensional phase plane with inversion height and boundary-layer average aerosol concentrations as the state variables. Simulations with a full diurnal cycle show similar evolutions, except that open-cell formation is phase-locked into the early morning hours. The same steadily-forced modeling framework is applied to the development and evolution of a POC and the surrounding overcast boundary layer. An initial aerosol perturbation applied to a portion of the model domain leads that portion to transition into open-cell convection, forming a POC. Reduced entrainment in the POC induces a negative feedback between areal fraction covered by the POC and boundary layer depth changes. This stabilizes the system by controlling liquid water path and precipitation sinks of aerosol number in the overcast region, while also preventing boundary-layer collapse within the POC, allowing the POC and overcast to coexist indefinitely in a quasi-steady equilibrium.

p53 AND MDM2 PROTEIN EXPRESSION IN ACTINIC CHEILITIS

PubMed Central

de Freitas, Maria da Conceição Andrade; Ramalho, Luciana Maria Pedreira; Xavier, Flávia Caló Aquino; Moreira, André Luis Gomes; Reis, Sílvia Regina Almeida

2008-01-01

Actinic cheilitis is a potentially malignant lip lesion caused by excessive and prolonged exposure to ultraviolet radiation, which can lead to histomorphological alterations indicative of abnormal cell differentiation. In this pathology, varying degrees of epithelial dysplasia may be found. There are few published studies regarding the p53 and MDM2 proteins in actinic cheilitis. Fifty-eight cases diagnosed with actinic cheilitis were histologically evaluated using Banóczy and Csiba (1976) parameters, and were subjected to immunohistochemical analysis using the streptavidin-biotin method in order to assess p53 and MDM2 protein expression. All studied cases expressed p53 proteins in basal and suprabasal layers. In the basal layer, the nuclei testing positive for p53 were stained intensely, while in the suprabasal layer, cells with slightly stained nuclei were predominant. All cases also tested positive for the MDM2 protein, but with varying degrees of nuclear expression and a predominance of slightly stained cells. A statistically significant correlation between the percentage of p53 and MDM2-positive cells was established, regardless of the degree of epithelial dysplasia. The expression of p53 and MDM2 proteins in actinic cheilitis can be an important indicator in lip carcinogenesis, regardless of the degree of epithelial dysplasia. PMID:19082401

p53 and MDM2 protein expression in actinic cheilitis.

PubMed

de Freitas, Maria da Conceição Andrade; Ramalho, Luciana Maria Pedreira; Xavier, Flávia Caló Aquino; Moreira, André Luis Gomes; Reis, Sílvia Regina Almeida

2008-01-01

Actinic cheilitis is a potentially malignant lip lesion caused by excessive and prolonged exposure to ultraviolet radiation, which can lead to histomorphological alterations indicative of abnormal cell differentiation. In this pathology, varying degrees of epithelial dysplasia may be found. There are few published studies regarding the p53 and MDM2 proteins in actinic cheilitis. Fifty-eight cases diagnosed with actinic cheilitis were histologically evaluated using Banóczy and Csiba (1976) parameters, and were subjected to immunohistochemical analysis using the streptavidin-biotin method in order to assess p53 and MDM2 protein expression. All studied cases expressed p53 proteins in basal and suprabasal layers. In the basal layer, the nuclei testing positive for p53 were stained intensely, while in the suprabasal layer, cells with slightly stained nuclei were predominant. All cases also tested positive for the MDM2 protein, but with varying degrees of nuclear expression and a predominance of slightly stained cells. A statistically significant correlation between the percentage of p53 and MDM2-positive cells was established, regardless of the degree of epithelial dysplasia. The expression of p53 and MDM2 proteins in actinic cheilitis can be an important indicator in lip carcinogenesis, regardless of the degree of epithelial dysplasia.

First insight on the impact of an osteoblastic layer on the bio-tribocorrosion performance of Ti6Al4V hip implants.

PubMed

Runa, M J; Mathew, M T; Fernandes, M H; Rocha, L A

2015-01-01

In uncemented Ti6Al4V hip implants, the bone-stem interface is subjected to cyclic loading motion driven by the daily activities of the patients, which may lead to the complete failure of the implant in the long term. It may also compromise the proliferation and differentiation processes of osteoblastic cells (bone-forming cells). The main objective of this work is to approach for the first time the role of these organic materials on the bio-tribocorrosion mechanisms of cultured Ti6Al4V alloys. The colonized materials with MG63 osteoblastic-like cells were characterized through cell viability/proliferation and enzymatic activity. Tribocorrosion tests were performed under a reciprocating sliding configuration and low contact pressure. Electrochemical techniques were used to measure the corrosion kinetics of the system, under free potential conditions. All tests were performed at a controlled atmosphere. The morphology and topography of the wear scar were evaluated. The results showed that the presence of an osteoblastic cell layer on the implant surface significantly influences the tribocorrosion behavior of Ti6Al4V alloy. It was concluded that the cellular material was able to form an extra protective layer that inhibits further wear degradation of the alloy and decreases its corrosion tendency. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of fluoride and chlorhexidine digluconate mouthrinses on plaque biofilms.

PubMed

Rabe, Per; Twetman, Svante; Kinnby, Bertil; Svensäter, Gunnel; Davies, Julia R

2015-01-01

To develop a model in which to investigate the architecture of plaque biofilms formed on enamel surfaces in vivo and to compare the effects of anti-microbial agents of relevance for caries on biofilm vitality. Materials and Methodology : Enamel discs mounted on healing abutments in the pre-molar region were worn by three subjects for 7 days. Control discs were removed before subjects rinsed with 0.1% chlorhexidine digluconate (CHX) or 0.2% sodium fluoride (NaF) for 1 minute. Biofilms were stained with Baclight Live/Dead and z-stacks of images created using confocal scanning laser micoscopy. The levels of vital and dead/damaged bacteria in the biofilms, assessed as the proportion of green and red pixels respectively, were analysed using ImageTrak(®) software. Results : The subjects showed individual differences in biofilm architecture. The thickness of the biofilms varied from 28-96µm although cell density was always the greatest in the middle layers. In control biofilms, the overall levels of vitality were high (71-98%) especially in the area closest to the enamel interface. Rinsing with either CHX or NaF caused a similar reduction in overall vitality. CHX exerted an effect throughout the biofilm, particularly on the surface of cell clusters whereas NaF caused cell damage/death mainly in the middle to lower biofilm layers. Conclusion : We describe a model that allows the formation of mature, undisturbed oral biofilms on human enamel surfaces in vivo and show that CHX and NaF have a similar effect on overall vitality but differ in their sites of action.

Tomographic Structural Changes of Retinal Layers after Internal Limiting Membrane Peeling for Macular Hole Surgery.

PubMed

Faria, Mun Yueh; Ferreira, Nuno P; Cristóvao, Diana M; Mano, Sofia; Sousa, David Cordeiro; Monteiro-Grillo, Manuel

2018-01-01

To highlight tomographic structural changes of retinal layers after internal limiting membrane (ILM) peeling in macular hole surgery. Nonrandomized prospective, interventional study in 38 eyes (34 patients) subjected to pars plana vitrectomy and ILM peeling for idiopathic macular hole. Retinal layers were assessed in nasal and temporal regions before and 6 months after surgery using spectral domain optical coherence tomography. Total retinal thickness increased in the nasal region and decreased in the temporal region. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) showed thinning on both nasal and temporal sides of the fovea. The thickness of the outer plexiform layer (OPL) increased. The outer nuclear layer (ONL) and outer retinal layers (ORL) increased in thickness after surgery in both nasal and temporal regions. ILM peeling is associated with important alterations in the inner retinal layer architecture, with thinning of the RNFL-GCL-IPL complex and thickening of OPL, ONL, and ORL. These structural alterations can help explain functional outcome and could give indications regarding the extent of ILM peeling, even though peeling seems important for higher rate of hole closure. © 2017 S. Karger AG, Basel.

A Laminated Microfluidic Device for Comprehensive Preclinical Testing in the Drug ADME Process

PubMed Central

An, Fan; Qu, Yueyang; Luo, Yong; Fang, Ning; Liu, Yang; Gao, Zhigang; Zhao, Weijie; Lin, Bingcheng

2016-01-01

New techniques are urgently needed to replace conventional long and costly pre-clinical testing in the new drug administration process. In this study, a laminated microfluidic device was fabricated to mimic the drug ADME response test in vivo. This proposed device was loaded and cultured with functional cells for drug response investigation and organ tissues that are involved in ADME testing. The drug was introduced from the top of the device and first absorbed by the Caco-2 cell layer, and then metabolized by the primary hepatocyte layer. It subsequently interacted with the MCF-7 cell layer, distributed in the lung, heart and fat tissues, and was finally eliminated through the dialysis membrane. Throughout this on-chip ADME process, the proposed device can be used as a reliable tool to simultaneously evaluate the drug anti-tumor activity, hepatotoxicity and pharmacokinetics. Furthermore, this device was proven to be able to reflect the hepatic metabolism of a drug, drug distribution in the target tissues, and the administration method of a drug. Furthermore, this microdevice is expected to reduce the number of drug candidates and accelerate the pre-clinical testing process subject to animal testing upon adaptation in new drug discovery. PMID:27122192

Mechanical characterization and durability of sintered porous transport layers for polymer electrolyte membrane electrolysis

NASA Astrophysics Data System (ADS)

Borgardt, Elena; Panchenko, Olha; Hackemüller, Franz Josef; Giffin, Jürgen; Bram, Martin; Müller, Martin; Lehnert, Werner; Stolten, Detlef

2018-01-01

Differential pressure electrolysis offers the potential for more efficient hydrogen compression. Due to the differential pressures acting within the electrolytic cell, the porous transport layer (PTL) is subjected to high stress. For safety reasons, the PTL's mechanical stability must be ensured. However, the requirements for high porosity and low thickness stand in contrast to that for mechanical stability. Porous transport layers for polymer electrolyte membrane (PEM) electrolysis are typically prepared by means of the thermal sintering of titanium powder. Thus far, the factors that influence the mechanical strength of the sintered bodies and how all requirements can be simultaneously fulfilled have not been investigated. Here, the static and dynamic mechanical properties of thin sintered titanium sheets are investigated ex-situ via tensile tests and periodic loading in a test cell, respectively. In order for a sintered PTL with a thickness of 500 μm and porosities above 25% to be able to withstand 50 bar differential pressure in the cell, the maximum flow field width should be limited to 3 mm. Thus, a method was developed to test the suitability of PTL materials for use in electrolysis for various differential pressures and flow field widths.

A Laminated Microfluidic Device for Comprehensive Preclinical Testing in the Drug ADME Process.

PubMed

An, Fan; Qu, Yueyang; Luo, Yong; Fang, Ning; Liu, Yang; Gao, Zhigang; Zhao, Weijie; Lin, Bingcheng

2016-04-28

New techniques are urgently needed to replace conventional long and costly pre-clinical testing in the new drug administration process. In this study, a laminated microfluidic device was fabricated to mimic the drug ADME response test in vivo. This proposed device was loaded and cultured with functional cells for drug response investigation and organ tissues that are involved in ADME testing. The drug was introduced from the top of the device and first absorbed by the Caco-2 cell layer, and then metabolized by the primary hepatocyte layer. It subsequently interacted with the MCF-7 cell layer, distributed in the lung, heart and fat tissues, and was finally eliminated through the dialysis membrane. Throughout this on-chip ADME process, the proposed device can be used as a reliable tool to simultaneously evaluate the drug anti-tumor activity, hepatotoxicity and pharmacokinetics. Furthermore, this device was proven to be able to reflect the hepatic metabolism of a drug, drug distribution in the target tissues, and the administration method of a drug. Furthermore, this microdevice is expected to reduce the number of drug candidates and accelerate the pre-clinical testing process subject to animal testing upon adaptation in new drug discovery.

Light-Responsive and pH-Responsive DNA Microcapsules for Controlled Release of Loads.

PubMed

Huang, Fujian; Liao, Wei-Ching; Sohn, Yang Sung; Nechushtai, Rachel; Lu, Chun-Hua; Willner, Itamar

2016-07-20

A method to assemble light-responsive or pH-responsive microcapsules loaded with different loads (tetramethylrhodamine-modified dextran, TMR-D; microperoxidase-11, MP-11; CdSe/ZnS quantum dots; or doxorubicin-modified dextran, DOX-D) is described. The method is based on the layer-by-layer deposition of sequence-specific nucleic acids on poly(allylamine hydrochloride)-functionalized CaCO3 core microparticles, loaded with the different loads, that after the dissolution of the core particles with EDTA yields the stimuli-responsive microcapsules that include the respective loads. The light-responsive microcapsules are composed of photocleavable o-nitrobenzyl-phosphate-modified DNA shells, and the pH-responsive microcapsules are made of a cytosine-rich layer cross-linked by nucleic acid bridges. Irradiating the o-nitrobenzyl phosphate-functionalized microcapsules, λ = 365 nm, or subjecting the pH-responsive microcapsules to pH = 5.0, results in the cleavage of the microcapsule shells and the release of the loads. Preliminary studies address the cytotoxicity of the DOX-D-loaded microcapsules toward MDA-MB-231 breast cancer cells and normal MCF-10A breast epithelial cells. Selective cytotoxicity of the DOX-D-loaded microcapsules toward cancer cells is demonstrated.

Characteristics of water and ion exchange of Elodea nuttallii cells at high concentrations of lanthanides.

PubMed

Vorob'ev, Vladimir N; Mirziev, Samat I; Alexandrov, Evgeniy A; Sibgatullin, Timur A

2016-12-01

Changes of diffusive permeability of membranes of Elodea nuttallii cells following a short-term (60 min) treatment with high concentrations of lanthanides were recorded by the 1 H NMR-diffusometry and conductometry methods. The 1-h infiltration of segments of Elodea nuttallii internodes in 10 mM solutions of nitrates of La, Nd and Lu resulted in the increased leakage of electrolytes from cells, but has no effect on a water diffusive permeability of membranes. In samples subjected to a 30 min pretreatment with a water channel inhibitor HgCl 2 the water diffusive permeability of membranes (P d ) drops down under the influence of lanthanides, as well as an outcome of electrolytes. To explain the observed effects the change of spontaneous curvature of membrane lipid layer has been taken into consideration. The interaction of lanthanides with lipids of plasmalemma leads to the negative spontaneous curvature of lipid layer at which membrane channels are unclosed. Blocking of the ionic and water channels by mercury ions compensate the effect of change of spontaneous curvature of lipid layer. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ratiometric analysis of optical coherence tomography-measured in vivo retinal layer thicknesses for the detection of early diabetic retinopathy.

PubMed

Bhaduri, Basanta; Shelton, Ryan L; Nolan, Ryan M; Hendren, Lucas; Almasov, Alexandra; Labriola, Leanne T; Boppart, Stephen A

2017-11-01

Influence of diabetes mellitus (DM) and diabetic retinopathy (DR) on parafoveal retinal thicknesses and their ratios was evaluated. Six retinal layer boundaries were segmented from spectral-domain optical coherence tomography images using open-source software. Five study groups: (1) healthy control (HC) subjects, and subjects with (2) controlled DM, (3) uncontrolled DM, (4) controlled DR and (5) uncontrolled DR, were identified. The one-way analyses of variance (ANOVA) between adjacent study groups (i. e. 1 with 2, 2 with 3, etc) indicated differences in retinal thicknesses and ratios. Overall retinal thickness, ganglion cell layer (GCL) thickness, inner plexiform layer (IPL) thickness, and their combination (GCL+ IPL), appeared to be significantly less in the uncontrolled DM group when compared to controlled DM and controlled DR groups. Although the combination of nerve fiber layer (NFL) and GCL, and IPL thicknesses were not different, their ratio, (NFL+GCL)/IPL, was found to be significantly higher in the controlled DM group compared to the HC group. Comparisons of the controlled DR group with the controlled DM group, and with the uncontrolled DR group, do not show any differences in the layer thicknesses, though several significant ratios were obtained. Ratiometric analysis may provide more sensitive parameters for detecting changes in DR. Picture: A representative segmented OCT image of the human retina is shown. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evidence for Chemical and Electronic Nonuniformities in the Formation of the Interface of RbF-Treated Cu(In,Ga)Se2 with CdS.

PubMed

Nicoara, Nicoleta; Kunze, Thomas; Jackson, Philip; Hariskos, Dimitrios; Duarte, Roberto Félix; Wilks, Regan G; Witte, Wolfram; Bär, Marcus; Sadewasser, Sascha

2017-12-20

We report on the initial stages of CdS buffer layer formation on Cu(In,Ga)Se 2 (CIGSe) thin-film solar cell absorbers subjected to rubidium fluoride (RbF) postdeposition treatment (PDT). A detailed characterization of the CIGSe/CdS interface for different chemical bath deposition (CBD) times of the CdS layer is obtained from spatially resolved atomic and Kelvin probe force microscopy and laterally integrating X-ray spectroscopies. The observed spatial inhomogeneity in the interface's structural, chemical, and electronic properties of samples undergoing up to 3 min of CBD treatments is indicative of a complex interface formation including an incomplete coverage and/or nonuniform composition of the buffer layer. It is expected that this result impacts solar cell performance, in particular when reducing the CdS layer thickness (e.g., in an attempt to increase the collection in the ultraviolet wavelength region). Our work provides important findings on the absorber/buffer interface formation and reveals the underlying mechanism for limitations in the reduction of the CdS thickness, even when an alkali PDT is applied to the CIGSe absorber.

Age-dependent differences in myelin basic protein expression in the hippocampus of young, adult and aged gerbils

PubMed Central

Ahn, Ji Hyeon; Lee, Tae-Kyeong; Park, Joon Ha; Cho, Jeong Hwi; Kim, In Hye; Lee, Jae Chul; Hong, Seongkweon; Jeon, Yong Hwan; Kang, Il Jun; Lee, Young Joo

2017-01-01

Myelin degeneration is one of the characteristics of aging and degenerative diseases. This study investigated age-related alterations in expression of myelin basic protein (MBP) in the hippocampal subregions (dentate gyrus, CA2/3 and CA1 areas) of gerbils of various ages; young (1 month), adult (6 months) and aged (24 months), using western blot and immunohistochemistry. Western blot results showed tendencies of age-related reductions of MBP levels. MBP immunoreactivity was significantly decreased with age in synaptic sites of trisynaptic loops, perforant paths, mossy fibers, and Schaffer collaterals. In particular, MBP immunoreactive fibers in the dentate molecular cell layer (perforant path) was significantly reduced in adult and aged subjects. In addition, MBP immunoreactive mossy fibers in the dentate polymorphic layer and in the CA3 striatum radiatum was significantly decreased in the aged group. Furthermore, we observed similar age-related alterations in the CA1 stratum radiatum (Schaffer collaterals). However, the density of MBP immunoreactive fibers in the dentate granular cell layer and CA stratum pyramidale was decreased with aging. These findings indicate that expression of MBP is age-dependent and tissue specific according to hippocampal layers. PMID:29046699

Profile and Determinants of Retinal Optical Intensity in Normal Eyes with Spectral Domain Optical Coherence Tomography.

PubMed

Chen, Binyao; Gao, Enting; Chen, Haoyu; Yang, Jianling; Shi, Fei; Zheng, Ce; Zhu, Weifang; Xiang, Dehui; Chen, Xinjian; Zhang, Mingzhi

2016-01-01

To investigate the profile and determinants of retinal optical intensity in normal subjects using 3D spectral domain optical coherence tomography (SD OCT). A total of 231 eyes from 231 healthy subjects ranging in age from 18 to 80 years were included and underwent a 3D OCT scan. Forty-four eyes were randomly chosen to be scanned by two operators for reproducibility analysis. Distribution of optical intensity of each layer and regions specified by the Early Treatment of Diabetic Retinopathy Study (ETDRS) were investigated by analyzing the OCT raw data with our automatic graph-based algorithm. Univariate and multivariate analyses were performed between retinal optical intensity and sex, age, height, weight, spherical equivalent (SE), axial length, image quality, disc area and rim/disc area ratio (R/D area ratio). For optical intensity measurements, the intraclass correlation coefficient of each layer ranged from 0.815 to 0.941, indicating good reproducibility. Optical intensity was lowest in the central area of retinal nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer and photoreceptor layer, except for the retinal pigment epithelium (RPE). Optical intensity was positively correlated with image quality in all retinal layers (0.553<β<0.851, p<0.01), and negatively correlated with age in most retinal layers (-0.362<β<-0.179, p<0.01), except for the RPE (β = 0.456, p<0.01), outer nuclear layer and photoreceptor layer (p>0.05). There was no relationship between retinal optical intensity and sex, height, weight, SE, axial length, disc area and R/D area ratio. There was a specific pattern of distribution of retinal optical intensity in different regions. The optical intensity was affected by image quality and age. Image quality can be used as a reference for normalization. The effect of age needs to be taken into consideration when using OCT for diagnosis.

Monitoring apoptosis in real time.

PubMed

Green, Allan M; Steinmetz, Neil D

2002-01-01

Many therapeutically active anticancer treatments exert their effect by the induction of apoptosis and necrosis. Serial biopsies in breast cancer patients have suggested that response to therapy correlates with early posttreatment increases in tumor apoptotic index. Radiolabeled technetium Tc 99m-recombinant human (rh) annexin V provides a noninvasive technique for imaging treatment-induced cell death. Annexin V is a naturally occurring human protein that binds avidly to membrane-associated phosphatidylserine (PS). PS is normally found only on the inner leaflet of the cell membrane double layer, but it is actively transported to the outer layer as an early event in apoptosis and becomes available for annexin binding. Annexin also gains access to PS as a result of the membrane fragmentation associated with necrosis. In vitro studies of apoptosis using fluorescein annexin have shown good correlation with assessments of apoptosis documented by nuclear DNA degradation and caspase activation. In vivo localization of intravenously administered Tc 99m-annexin V has been demonstrated in numerous preclinical models of apoptosis, including anti-Fas-mediated hepatic apoptosis, rejection of allogeneic heterotopic cardiac allografts, cyclophosphamide treatment of murine lymphoma, cyclophosphamide-induced apoptosis in bone marrow, and leukocyte apoptosis associated with abscess formation. Scintigraphic studies in humans using Tc 99m-rh annexin V have demonstrated the feasibility of imaging cell death in acute myocardial infarction, in tumors with a high apoptotic index, and in response to anti-tumor chemotherapy of non-small cell lung cancer, small-cell lung cancer, breast cancer, lymphoma, and sarcoma. Increased localization of Tc 99m-rh annexin V within 1 to 3 days of chemotherapy has been noted in some, but not all, subjects with these tumors. To date, most subjects showing increased Tc 99m-rh annexin V uptake after the first course of chemotherapy have shown objective clinical responses. A single site study in 15 subjects with 1-year follow-up has suggested that increased posttreatment Tc 99m-rh annexin uptake is associated with improved time to progression of disease and survival time. In vivo imaging of cell death may have the potential to improve the treatment of cancer patients by allowing rapid, objective, patient-by-patient assessment of the efficacy of tumor cell killing.

Age-Related Alterations in the Retinal Microvasculature, Microcirculation, and Microstructure

PubMed Central

Wei, Yantao; Jiang, Hong; Shi, Yingying; Qu, Dongyi; Gregori, Giovanni; Zheng, Fang; Rundek, Tatjana; Wang, Jianhua

2017-01-01

Purpose To characterize age-related alterations in the retinal microcirculation, microvascular network, and microstructure in healthy subjects. Methods Seventy-four healthy subjects aged from 18 to 82 years were recruited and divided into four age groups (G1 with age <35 years, G2 with age 35 ∼ 49 years, G3 with age 50 ∼ 64 years, and G4 with age ≥65 years). Custom ultra-high resolution optical coherence tomography (UHR-OCT) was used to acquire six intraretinal layers of the macula. OCT angiography (OCTA) was used to image the retinal microvascular network. The retinal blood flow velocity (BFV) was measured using a Retinal Function Imager (RFI). Results Compared to G1, G2 had significant thinning of the retinal nerve fiber layer (RNFL) (P < 0.05), while G3 had thinning of the RNFL and ganglion cell and inner plexiform layer (GCIPL) (P < 0.05), in addition to thickening of the outer plexiform layer (OPL) and photoreceptor layer (PR) (P < 0.05). G4 had loss in retinal vessel density, thinning in RNFL and GCIPL, and decrease in venular BFV, in addition to thickening of the OPL and PR (P < 0.05). Age was negatively related to retinal vessel densities, the inner retinal layers, and venular BFV (P < 0.05). By contrast, age was positively related to OPL and PR (P < 0.05). Conclusions During aging, decreases in retinal vessel density, inner retinal layer thickness, and venular BFV were evident and impacted each other as observed by simultaneous changes in multiple retinal components. PMID:28744554

Impacts of age and sex on retinal layer thicknesses measured by spectral domain optical coherence tomography with Spectralis.

PubMed

Nieves-Moreno, María; Martínez-de-la-Casa, José M; Morales-Fernández, Laura; Sánchez-Jean, Rubén; Sáenz-Francés, Federico; García-Feijoó, Julián

2018-01-01

To examine differences in individual retinal layer thicknesses measured by spectral domain optical coherence tomography (SD-OCT) (Spectralis®) produced with age and according to sex. Cross-sectional, observational study. The study was conducted in 297 eyes of 297 healthy subjects aged 18 to 87 years. In one randomly selected eye of each participant the volume and mean thicknesses of the different macular layers were measured by SD-OCT using the instrument's macular segmentation software. Volume and mean thickness of macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), retinal pigmentary epithelium (RPE) and photoreceptor layer (PR). Retinal thickness was reduced by 0.24 μm for every one year of age. Age adjusted linear regression analysis revealed mean GCL, IPL, ONL and PR thickness reductions and a mean OPL thickness increase with age. Women had significantly lower mean GCL, IPL, INL, ONL and PR thicknesses and volumes and a significantly greater mRNFL volume than men. The thickness of most retinal layers varies both with age and according to sex. Longitudinal studies are needed to determine the rate of layer thinning produced with age.

ZEB1 is Estrogen Responsive In Vitro in Human Foreskin Cells and is Over Expressed in Penile Skin in Patients With Severe Hypospadias

PubMed Central

Qiao, Liang; Tasian, Gregory E.; Zhang, Haiyang; Cunha, Gerald R.; Baskin, Laurence

2012-01-01

Purpose We determined the effect of estrogen on ZEB1 in vitro and tested the hypothesis that ZEB1 is over expressed in the penile skin of subjects with hypospadias. Materials and Methods Hs68 cells, a fibroblast cell line derived from human foreskin, were exposed to 0, 1, 10 and 100 nM estrogen, and the expression level of ZEB1 was assessed using reverse transcription real-time polymerase chain reaction, Western blot and immunocytochemical analysis. Next, preputial skin was prospectively collected from case and control subjects at hypospadias repair (37 cases) and circumcision (11). Hypospadias was classified as severe (13 cases) or mild (24) based on the position of the urethral meatus. ZEB1 expression was quantified using reverse transcription real-time polymerase chain reaction, Western blot and immunohistochemical analysis. Results Estrogen increased ZEB1 expression at the mRNA and protein levels in Hs68 cells in a concentration dependent fashion (p <0.01). Subjects with severe hypospadias had significantly higher ZEB1 mRNA levels and protein expression compared to controls or subjects with mild hypospadias (both p <0.01). Subjects with severe hypospadias had increased expression of ZEB1 in the basal layers of the preputial epidermis. Conclusions Estrogen increases ZEB1 expression in a human foreskin fibroblast cell line in vitro. Furthermore, ZEB1 is significantly over expressed in the penile skin of subjects with severe hypospadias. We propose that ZEB1 overexpression may contribute to development of hypospadias and may mediate the effect of estrogen on developing external male genitalia. PMID:21421232

Food restriction enhances oxidative status in aging rats with neuroprotective effects on myenteric neuron populations in the proximal colon.

PubMed

Schoffen, João Paulo Ferreira; Santi Rampazzo, Ana Paula; Cirilo, Carla Possani; Zapater, Mariana Cristina Umada; Vicentini, Fernando Augusto; Comar, Jurandir Fernando; Bracht, Adelar; Natali, Maria Raquel Marçal

2014-03-01

Food restriction may slow the aging process by increasing the levels of antioxidant defenses and reducing cell death. We evaluated the effects of food restriction on oxidative and nutritional status, myenteric cell populations, and the colonic muscle layer in aging rats. Wistar rats were distributed into control groups (7, 12, and 23months of age) and subjected to food restriction (50% of normal diet) beginning at 7months of age. The animals were sacrificed, and blood was collected to evaluate its components and markers of oxidative status, including thiobarbituric acid-reactive substances, reduced glutathione, catalase, glutathione peroxidase, and total antioxidant capacity. The proximal colon was collected to evaluate HuC/D and neuronal nitric oxide synthase (nNOS)-positive and -negative myenteric neurons, S-100 glial cells, and the muscle layer. Age negatively affected oxidative status in the animals, which also increased the levels of total cholesterol, protein, and globulins and increased the thickness of the muscle layer. Aging also reduced the number and hypertrophied glial cell bodies, HuC/D neurons, and nNOS-negative and -positive neurons. An improvement was observed in oxidative status and the levels of total cholesterol and triglycerides with food restriction, which also provided neuroprotection of the intrinsic innervation. However, food restriction accentuated the loss of enteric glia and caused hypertrophy in the muscle layer at 23months. Food restriction improved oxidative and nutritional status in rats and protected HuC/D neurons and nNOS-negative and -positive neurons against neuronal loss. Nevertheless, food restriction caused morphoquantitative changes in glial cell populations, with possible interference with colonic neuromuscular control. Copyright © 2014 Elsevier Inc. All rights reserved.

Conductive polymer layers to limit transfer of fuel reactants to catalysts of fuel cells to reduce reactant crossover

DOEpatents

Stanis, Ronald J.; Lambert, Timothy N.

2016-12-06

An apparatus of an aspect includes a fuel cell catalyst layer. The fuel cell catalyst layer is operable to catalyze a reaction involving a fuel reactant. A fuel cell gas diffusion layer is coupled with the fuel cell catalyst layer. The fuel cell gas diffusion layer includes a porous electrically conductive material. The porous electrically conductive material is operable to allow the fuel reactant to transfer through the fuel cell gas diffusion layer to reach the fuel cell catalyst layer. The porous electrically conductive material is also operable to conduct electrons associated with the reaction through the fuel cell gas diffusion layer. An electrically conductive polymer material is coupled with the fuel cell gas diffusion layer. The electrically conductive polymer material is operable to limit transfer of the fuel reactant to the fuel cell catalyst layer.

Normative Database and Color-code Agreement of Peripapillary Retinal Nerve Fiber Layer and Macular Ganglion Cell-inner Plexiform Layer Thickness in a Vietnamese Population.

PubMed

Perez, Claudio I; Chansangpetch, Sunee; Thai, Andy; Nguyen, Anh-Hien; Nguyen, Anwell; Mora, Marta; Nguyen, Ngoc; Lin, Shan C

2018-06-05

Evaluate the distribution and the color probability codes of the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL) thickness in a healthy Vietnamese population and compare them with the original color-codes provided by the Cirrus spectral domain OCT. Cross-sectional study. We recruited non-glaucomatous Vietnamese subjects and constructed a normative database for peripapillary RNFL and macular GCIPL thickness. The probability color-codes for each decade of age were calculated. We evaluated the agreement with Kappa coefficient (κ) between OCT color probability codes with Cirrus built-in original normative database and the Vietnamese normative database. 149 eyes of 149 subjects were included. The mean age of enrollees was 60.77 (±11.09) years, with a mean spherical equivalent of +0.65 (±1.58) D and mean axial length of 23.4 (±0.87) mm. Average RNFL thickness was 97.86 (±9.19) microns and average macular GCIPL was 82.49 (±6.09) microns. Agreement between original and adjusted normative database for RNFL was fair for average and inferior quadrant (κ=0.25 and 0.2, respectively); and good for other quadrants (range: κ=0.63-0.73). For macular GCIPL κ agreement ranged between 0.39 and 0.69. After adjusting with the normative Vietnamese database, the percent of yellow and red color-codes increased significantly for peripapillary RNFL thickness. Vietnamese population has a thicker RNFL in comparison with Cirrus normative database. This leads to a poor color-code agreement in average and inferior quadrant between the original and adjusted database. These findings should encourage to create a peripapillary RNFL normative database for each ethnicity.

Selective Thinning of the Perifoveal Inner Retina as an Early Sign of Hydroxychloroquine Retinal Toxicity

PubMed Central

Pasadhika, Sirichai; Fishman, Gerald A; Choi, Dongseok; Shahidi, Mahnaz

2013-01-01

Purpose To evaluate macular thickness profiles using spectral-domain optical coherence tomography (SDOCT) and image segmentation in patients with chronic exposure to hydroxychloroquine. Methods This study included 8 patients with chronic exposure to hydroxychloroquine (Group 1) and 8 controls (Group 2). Group 1 patients had no clinically-evident retinal toxicity. All subjects underwent SDOCT imaging of the macula. An image segmentation technique was used to measure thickness of 6 retinal layers at 200 µm intervals. A mixed-effects model was used for multivariate analysis. Results By measuring total retinal thickness either at the central macular (2800 µm in diameter), the perifoveal region 1200-µm-width ring surrounding the central macula), or the overall macular area (5200 µm in diameter), there were no significant differences in the thickness between Groups 1 and 2. On an image segmentation analysis, selective thinning of the inner plexiform + ganglion cell layers (p=0.021) was observed only in the perifoveal area of the patients in Group 1 compared to that of Group 2 by using the mixed-effects model analysis. Conclusions Our results suggest that chronic exposure to hydroxychloroquine is associated with thinning of the perifoveal inner retinal layers, especially in the ganglion cell and inner plexiform layers, even in the absence of functional or structural clinical changes involving the photoreceptor or retinal pigment epithelial cell layers. This may be a contributing factor as the reason most patients who have early detectable signs of drug toxicity present with paracentral or pericentral scotomas. PMID:20395978

Influence of Smear Layer on the Antimicrobial Activity of a Sodium Hypochlorite/Etidronic Acid Irrigating Solution in Infected Dentin.

PubMed

Morago, Ana; Ordinola-Zapata, Ronald; Ferrer-Luque, Carmen María; Baca, Pilar; Ruiz-Linares, Matilde; Arias-Moliz, María Teresa

2016-11-01

The aim of this study was to evaluate the influence of the smear layer on the antimicrobial activity of a 2.5% sodium hypochlorite (NaOCl)/9% etidronic acid (HEBP) irrigating solution against bacteria growing inside dentin tubules. Dentin tubules were infected with Enterococcus faecalis by centrifugation. After 5 days of incubation, the smear layer had formed in half of the samples, which were then treated with 2.5% NaOCl either alone or combined with 9% HEBP for 3 minutes. The percentage of dead cells in infected dentinal tubules was measured using confocal laser scanning microscopy and the live/dead technique. The smear layer on the surface of the root canal wall was also observed by scanning electron microscopy. Results of the percentage of dead cells were compared using parametric tests after subjecting data to the normalized Anscombe transformation. The level of significance was P < .05. In the absence of the smear layer, 2.5% NaOCl alone and combined with 9% HEBP showed high antimicrobial activity without significant differences between the 2. The smear layer reduced the antimicrobial activity of 2.5% NaOCl significantly, whereas the solution with HEBP was not affected. No dentin tubules free of the smear layer were obtained in the 2.5% NaOCl group. In the case of 2.5% NaOCl/9% HEBP, 95.40% ± 3.63% of dentin tubules were cleaned. The presence of the smear layer reduced the antimicrobial activity of 2.5% NaOCl. The combination of 2.5% NaOCl/9% HEBP exerted antimicrobial activity that was not reduced by the smear layer. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Proliferative changes in the bronchial epithelium of former smokers treated with retinoids.

PubMed

Hittelman, Walter N; Liu, Diane D; Kurie, Jonathan M; Lotan, Reuben; Lee, Jin Soo; Khuri, Fadlo; Ibarguen, Heladio; Morice, Rodolfo C; Walsh, Garrett; Roth, Jack A; Minna, John; Ro, Jae Y; Broxson, Anita; Hong, Waun Ki; Lee, J Jack

2007-11-07

Retinoids have shown antiproliferative and chemopreventive activity. We analyzed data from a randomized, placebo-controlled chemoprevention trial to determine whether a 3-month treatment with either 9-cis-retinoic acid (RA) or 13-cis-RA and alpha-tocopherol reduced Ki-67, a proliferation biomarker, in the bronchial epithelium. Former smokers (n = 225) were randomly assigned to receive 3 months of daily oral 9-cis-RA (100 mg), 13-cis-RA (1 mg/kg) and alpha-tocopherol (1200 IU), or placebo. Bronchoscopic biopsy specimens obtained before and after treatment were immunohistochemically assessed for changes in the Ki-67 proliferative index (i.e., percentage of cells with Ki-67-positive nuclear staining) in the basal and parabasal layers of the bronchial epithelium. Per-subject and per-biopsy site analyses were conducted. Multicovariable analyses, including a mixed-effects model and a generalized estimating equations model, were used to investigate the treatment effect (Ki-67 labeling index and percentage of bronchial epithelial biopsy sites with a Ki-67 index > or = 5%) with adjustment for multiple covariates, such as smoking history and metaplasia. Coefficient estimates and 95% confidence intervals (CIs) were obtained from the models. All statistical tests were two-sided. In per-subject analyses, Ki-67 labeling in the basal layer was not changed by any treatment; the percentage of subjects with a high Ki-67 labeling in the parabasal layer dropped statistically significantly after treatment with 13-cis-RA and alpha-tocopherol treatment (P = .04) compared with placebo, but the drop was not statistically significant after 9-cis-RA treatment (P = .17). A similar effect was observed in the parabasal layer in a per-site analysis; the percentage of sites with high Ki-67 labeling dropped statistically significantly after 9-cis-RA treatment (coefficient estimate = -0.72, 95% CI = -1.24 to -0.20; P = .007) compared with placebo, and after 13-cis-RA and alpha-tocopherol treatment (coefficient estimate = -0.66, 95% CI = -1.15 to -0.17; P = .008). In per-subject analyses, treatment with 13-cis-RA and alpha-tocopherol, compared with placebo, was statistically significantly associated with reduced bronchial epithelial cell proliferation; treatment with 9-cis-RA was not. In per-site analyses, statistically significant associations were obtained with both treatments.

Proliferative Changes in the Bronchial Epithelium of Former Smokers Treated With Retinoids

PubMed Central

Hittelman, Walter N.; Liu, Diane D.; Kurie, Jonathan M.; Lotan, Reuben; Lee, Jin Soo; Khuri, Fadlo; Ibarguen, Heladio; Morice, Rodolfo C.; Walsh, Garrett; Roth, Jack A.; Minna, John; Ro, Jae Y.; Broxson, Anita; Hong, Waun Ki; Lee, J. Jack

2012-01-01

Background Retinoids have shown antiproliferative and chemopreventive activity. We analyzed data from a randomized, placebo-controlled chemoprevention trial to determine whether a 3-month treatment with either 9-cis-retinoic acid (RA) or 13-cis-RA and α-tocopherol reduced Ki-67, a proliferation biomarker, in the bronchial epithelium. Methods Former smokers (n = 225) were randomly assigned to receive 3 months of daily oral 9-cis-RA (100 mg), 13-cis-RA (1 mg/kg) and α-tocopherol (1200 IU), or placebo. Bronchoscopic biopsy specimens obtained before and after treatment were immunohistochemically assessed for changes in the Ki-67 proliferative index (i.e., percentage of cells with Ki-67–positive nuclear staining) in the basal and parabasal layers of the bronchial epithelium. Per-subject and per–biopsy site analyses were conducted. Multicovariable analyses, including a mixed-effects model and a generalized estimating equations model, were used to investigate the treatment effect (Ki-67 labeling index and percentage of bronchial epithelial biopsy sites with a Ki-67 index ≥ 5%) with adjustment for multiple covariates, such as smoking history and metaplasia. Coefficient estimates and 95% confidence intervals (CIs) were obtained from the models. All statistical tests were two-sided. Results In per-subject analyses, Ki-67 labeling in the basal layer was not changed by any treatment; the percentage of subjects with a high Ki-67 labeling in the parabasal layer dropped statistically significantly after treatment with 13-cis-RA and α-tocopherol treatment (P = .04) compared with placebo, but the drop was not statistically significant after 9-cis-RA treatment (P = .17). A similar effect was observed in the parabasal layer in a per-site analysis; the percentage of sites with high Ki-67 labeling dropped statistically significantly after 9-cis-RA treatment (coefficient estimate = −0.72, 95% CI = −1.24 to −0.20; P = .007) compared with placebo, and after 13-cis-RA and α-tocopherol treatment (coefficient estimate = −0.66, 95% CI = −1.15 to −0.17; P = .008). Conclusions In per-subject analyses, treatment with 13-cis-RA and α-tocopherol, compared with placebo, was statistically significantly associated with reduced bronchial epithelial cell proliferation; treatment with 9-cis-RA was not. In per-site analyses, statistically significant associations were obtained with both treatments. PMID:17971525

Photovoltaic cell module and method of forming

DOEpatents

Howell, Malinda; Juen, Donnie; Ketola, Barry; Tomalia, Mary Kay

2017-12-12

A photovoltaic cell module, a photovoltaic array including at least two modules, and a method of forming the module are provided. The module includes a first outermost layer and a photovoltaic cell disposed on the first outermost layer. The module also includes a second outermost layer disposed on the photovoltaic cell and sandwiching the photovoltaic cell between the second outermost layer and the first outermost layer. The method of forming the module includes the steps of disposing the photovoltaic cell on the first outermost layer, disposing a silicone composition on the photovoltaic cell, and compressing the first outermost layer, the photovoltaic cell, and the second layer to form the photovoltaic cell module.

Understanding dynamic changes in live cell adhesion with neutron reflectometry

NASA Astrophysics Data System (ADS)

Junghans, Ann

Understanding the structure and functionality of biological systems on a nanometer-resolution and short temporal scales is important for solving complex biological problems, developing innovative treatment, and advancing the design of highly functionalized biomimetic materials. For example, adhesion of cells to an underlying substrate plays a crucial role in physiology and disease development, and has been investigated with great interest for several decades. In the talk, we would like to highlight recent advances in utilizing neutron scattering to study bio-related structures in dynamic conditions (e . g . under the shear flow) including in-situ investigations of the interfacial properties of living cells. The strength of neutron reflectometry is its non-pertubative nature, the ability to probe buried interfaces with nanometer resolution and its sensitivity to light elements like hydrogen and carbon. That allows us to study details of cell - substrate interfaces that are not accessible with any other standard techniques. We studied the adhesion of human brain tumor cells (U251) to quartz substrates and their responses to the external mechanical forces. Such cells are isolated within the central nervous system which makes them difficult to reach with conventional therapies and therefore making them highly invasive. Our results reveal changes in the thickness and composition of the adhesion layer (a layer between the cell lipid membrane and the quartz substrate), largely composed of hyaluronic acid and associated proteoglycans, when the cells were subjected to shear stress. Further studies will allow us to determine more conditions triggering changes in the composition of the bio-material in the adhesion layer. This, in turn, can help to identify changes that correlate with tumor invasiveness, which can have significant medical impact for the development of targeted anti-invasive therapies.

Metal based gas diffusion layers for enhanced fuel cell performance at high current densities

NASA Astrophysics Data System (ADS)

Hussain, Nabeel; Van Steen, Eric; Tanaka, Shiro; Levecque, Pieter

2017-01-01

The gas diffusion layer strongly influences the performance and durability of polymer electrolyte fuel cells. A major drawback of current carbon fiber based GDLs is the non-controlled variation in porosity resulting in a random micro-structure. Moreover, when subjected to compression these materials show significant reduction in porosity and permeability leading to water management problems and mass transfer losses within the fuel cell. This study investigated the use of uniform perforated metal sheets as GDLs in conjunction with microchannel flowfields. A metal sheet design with a pitch of 110 μm and a hole diameter of 60 μm in combination with an MPL showed superior performance in the high current density region compared to a commercially available carbon paper based GDL in a single cell environment. Fuel cell testing with different oxidants (air, heliox and oxygen) indicate that the metal sheet offers both superior diffusion and reduced flooding in comparison to the carbon based GDL. The presence of the MPL has been found to be critical to the functionality of the metal sheet suggesting that the MPL design may represent an important optimisation parameter for further improvements in performance.

Multimodal imaging of ocular surface of dry eye subjects

NASA Astrophysics Data System (ADS)

Zhang, Aizhong; Salahura, Gheorghe; Kottaiyan, Ranjini; Yoon, Geunyoung; Aquavella, James V.; Zavislan, James M.

2016-03-01

To study the relationship between the corneal lipid layer and the ocular surface temperature (OST), we conducted a clinical trial for 20 subjects. Subjects were clinically screened prior to the trial. Of the 20 subjects, 15 have Meibomian gland dysfunction (MGD), and 5 have aqueous-deficient dry eye (ADDE). A custom, circularly polarized illumination video tearscope measured the lipid layer thickness of the ocular tear film. A long-wave infrared video camera recorded the dynamic thermal properties of the ocular team film. The results of these two methods were analyzed and compared. Using principal component analysis (PCA) of the lipid layer distribution, we find that the 20 subjects could be categorized into five statistically significant groups, independent of their original clinical classification: thin (6 subjects), medium (5 subjects), medium and homogenous (3 subjects), thick (4 subjects), and very thick (2 subjects) lipids, respectively. We also conducted PCA of the OST data, and recategorized the subjects into two thermal groups by k-means clustering: one includes all ADDE subjects and some MGD subjects; the other includes the remaining MGD subjects. By comparing these two methods, we find that dry eye subjects with thin (<= 40 nm) lipids have significantly lower OST, and a larger OST drop range, potentially due to more evaporation. However, as long as the lipid layer is not thin (> 40 nm), there is no strong correlation between the lipid layer thickness and heterogeneity and the OST patterns.

Unitized Regenerative Fuel Cell System Gas Storage/Radiator Development

NASA Technical Reports Server (NTRS)

Jakupca, Ian; Burke, Kenneth A.

2003-01-01

The ancillary components for Unitized Regenerative Fuel Cell (URFC) Energy Storage System are being developed at the NASA Glenn Research Center. This URFC system is unique in that it uses the surface area of the hydrogen and oxygen storage tanks as radiating heat surfaces for overall thermal control of the system. The waste heat generated by the URFC stack during charging and discharging is transferred from the cell stack to the surface of each tank by loop heat pipes. The heat pipes are coiled around each tank and covered with a thin layer of thermally conductive layer of carbon composite. The thin layer of carbon composite acts as a fin structure that spreads the heat away from the heat pipe and across the entire tank surface. Two different sized commercial grade composite tanks were constructed with integral heat pipes and tested in a thermal vacuum chamber to examine the feasibility of using the storage tanks as system radiators. The storage radiators were subjected to different steady-state heat loads and varying heat load profiles. The surface emissivity and specific heat capacity of each tank were calculated. The results were incorporated into a model that simulates the performance of similar radiators using lightweight, space rated carbon composite tanks.

Failure analysis of fuel cell electrodes using three-dimensional multi-length scale X-ray computed tomography

NASA Astrophysics Data System (ADS)

Pokhrel, A.; El Hannach, M.; Orfino, F. P.; Dutta, M.; Kjeang, E.

2016-10-01

X-ray computed tomography (XCT), a non-destructive technique, is proposed for three-dimensional, multi-length scale characterization of complex failure modes in fuel cell electrodes. Comparative tomography data sets are acquired for a conditioned beginning of life (BOL) and a degraded end of life (EOL) membrane electrode assembly subjected to cathode degradation by voltage cycling. Micro length scale analysis shows a five-fold increase in crack size and 57% thickness reduction in the EOL cathode catalyst layer, indicating widespread action of carbon corrosion. Complementary nano length scale analysis shows a significant reduction in porosity, increased pore size, and dramatically reduced effective diffusivity within the remaining porous structure of the catalyst layer at EOL. Collapsing of the structure is evident from the combination of thinning and reduced porosity, as uniquely determined by the multi-length scale approach. Additionally, a novel image processing based technique developed for nano scale segregation of pore, ionomer, and Pt/C dominated voxels shows an increase in ionomer volume fraction, Pt/C agglomerates, and severe carbon corrosion at the catalyst layer/membrane interface at EOL. In summary, XCT based multi-length scale analysis enables detailed information needed for comprehensive understanding of the complex failure modes observed in fuel cell electrodes.

Spectral characterization of a pteridine derivative from cyanide-utilizing bacterium Bacillus subtilis - JN989651.

PubMed

Durairaju Nisshanthini, S; Teresa Infanta S, Antony K; Raja, Duraisamy Senthil; Natarajan, Karuppannan; Palaniswamy, M; Angayarkanni, Jayaraman

2015-04-01

Soil and water samples were collected from various regions of SIPCOT and nearby Vanappadi Lake, Ranipet, Tamilnadu, India. Based on their colony morphology and their stability during subculturing, 72 bacteria were isolated, of which 14 isolates were actinomycetes. Preliminary selection was carried out to exploit the ability of the microorganisms to utilize sodium cyanate as nitrogen source. Those organisms that were able to utilize cyanate were subjected to secondary screening viz., utilization of sodium cyanide as the nitrogen source. The oxygenolytic cleavage of cyanide is dependent on cyanide monooxygenase which obligately requires pterin cofactor for its activity. Based on this, the organisms capable of utilizing sodium cyanide were tested for the presence of pterin. Thin layer chromatography (TLC) of the cell extracts using n-butanol: 5 N glacial acetic acid (4:1) revealed that 10 out of 12 organisms that were able to utilize cyanide had the pterin-related blue fluorescent compound in the cell extract. The cell extracts of these 10 organisms were subjected to high performance thin layer chromatography (HPTLC) for further confirmation using a pterin standard. Based on the incubation period, cell biomass yield, peak height and area, strain VPW3 was selected and was identified as Bacillus subtilis. The Rf value of the cell extract was 0.73 which was consistent with the 0.74 Rf value of the pterin standard when scanned at 254 nm. The compound was extracted and purified by preparative High Performance Liquid Chromatography (HPLC). Characterization of the compound was performed by ultraviolet spectrum, fluorescence spectrum, Electrospray Ionization-Mass Spectrometry (ESI-MS), and Nuclear Magnetic Resonance spectroscopy (NMR). The compound is proposed to be 6-propionyl pterin (2-amino-6-propionyl-3H-pteridin-4-one).

Pulsed laser deposited MnCo{sub 2}O{sub 4} protective layer on SS430 for solid oxide fuel cell application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaur, Anshu, E-mail: gauranshu20@gmail.com, E-mail: ahamed.vza@gmail.com; Mohiddon, Md. Ahamad, E-mail: gauranshu20@gmail.com, E-mail: ahamed.vza@gmail.com; Prasad, Muvva D.

2016-05-23

The growth and oxidation study of pulsed laser deposited MnCo{sub 2}O{sub 4} protective layer on SS430 substrate for solid oxide fuel cell application is demonstrated. MnCo{sub 2}O{sub 4} has been achieved in three different ways including, deposition at higher substrate temperature (700°C), and deposition at room temperature on pre-oxidized and untreated SS430 substrate followed by annealing at 700°C for 2 hrs. X-ray diffraction and Raman spectroscopy has been applied to demonstrate the kind of phases developed in each case. These three samples were subjected to heat treatment at 750°C for 5 hr. The extent of undesired Fe{sub 2}O{sub 3} phasemore » formation in the post deposition heat treated samples is discussed based on Raman spectroscopic results.« less

In vivo immunomodulatory, cumulative skin irritation, sensitization and effect of d-limonene on permeation of 6-mercaptopurine through transdermal drug delivery.

PubMed

Chandrashekar, N S; Hiremath, Shobha Rani Rajeev

2008-04-01

Using skin as a port for systemic drug administration, transdermal drug delivery has expanded greatly over the last two decades. Our aim was to formulate the single layer drug-in-adhesive transdermal patch for 6-mercaptopurine (6-MP). In vitro permeation study was carried out using modified Franz diffusion cell with and without of different concentration of d-limonene in human cadaver skin. In vivo immunomodulatory was carried out in mice, cumulative skin irritation, sensitization and patch adherence study was done in both mice and human subjects. 6-MP flux increased from 43+/-12.2 microg/cm2h (control) to 162.8+/-32.2 microg/cm2h (6% w/v d-limonene) data was significant (p<0.05), with decrease in the lag time to 35+/-9.3 min compared to control of 90 +/-15.3 min. In vivo immunomodulatory effect was shown in the Balb/c mice with 100 mumol/kg/body wt of animal for 5d (one dose/d) of d-limonene. WBC count of 13469 cells/mm peak was observed on 12th day, bone marrow cells of 26.3 x 10(6) cells/femur and alpha-esterase positive cells of 1259+/-328.4 cells/4000 bone marrow cells. Cumulative skin irritation, sensitisation and patch adherence in animals and human subjects showed no skin irritation and sensitization. Patch adhesion was greater than 90.0% respectively in both human subjects and mice. The percentage of human subjects with adhesive residue was significantly less with scores of zero. d-Limonene proved as good chemical enhancer by increasing in the skin permeability with shortened the lag time. It proved that therapeutic amount of 6-MP can be delivered through transdermal drug delivery.

P3HT:PCBM-based organic solar cells : Optimisation of active layer nanostructure and interface properties

NASA Astrophysics Data System (ADS)

Kadem, Burak Yahya

Organic solar cells (OSCs) have attracted a significant attention during the last decade due to their simple processability on a flexible substrate as well as scope for large-scale production using role to role technique. Improving the performance of the organic solar cells and their lifetime stability are one of the main challenges faced by researchers in this field. In this thesis, work has been carried out using a blend of Poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-Phenyl C[61] butyric acid methyl ester (PCBM) as an active layer in the ratio of (1:1) (P3HT:PCBM). The efficiency and stability of P3HT:PCBM-based solar cells have been examined using different methods and employing novel materials such as1-[N-(2-ethoxyethyl) pent-4-ynamide] -8 (11), 15 (18), 22 (25) -tris-{2-[2-(2-ethoxyethoxy) ethoxy]-1-[2-((2- ethoxyethoxy) - ethoxy) methyl] ethyloxy} phthalocyaninato zinc (II) (ZnPc) to construct a ternary hybrid as the active layer. Controlling the morphology and crystallinity of P3HT:PCBM active layer was carried out using different solvents including chloroform (CF), chlorobenzene (CB) and dichlorobenzene (DCB) and their co-solvents in the ratio of (1:1) to dissolve the P3HT:PCBM blend. Optimum morphology and crystallinity were achieved using a co-solvent made of CB:CF with the obtained solar cell exhibiting the highest performance with PCE reaching 2.73% among other devices prepared using different solvents. Further device performance improvement was observed through optimization of active layer thickness with studied thickness falling in range 65-266 nm. Measurements of the PV characteristics of the investigated OSC devices have revealed optimum performance when active layer thickness was 95 nm with PCE=3.846%. The stability of the P3HT:PCBM-based devices on optimisation of the active layer thickness has shown a decrease in PCE of about 71% over a period of 41 days. Furthermore, P3HT has been blended with different fullerene derivatives (PC[60]BM, PC[61]BM, PC[70]BM and PC[71]BM) and the active layers were processed using the optimum solvent as well as optimum film's thickness.These PCBM derivatives have different lower unoccupied molecular level (LUMO) and different higher occupied molecular level (HOMO) positions, which subsequently influence the PV parameters of the OSCs such as the device open circuit voltage (V[oc]) and its built-in potential (V[bi]). P3HT:PC61BM-based blend has exhibited the highest device performance with PCE reaching 4.2%. Using the above mentioned optimum parameters, the P3HT:PCBM-based devices have been subjected to post-deposition annealing at different temperatures in the range 100-180°C. Efficient device performance was ascribed to P3HT:PCBM layers being subjected to post-deposition heat treatment at 140°C with PCE=5.5%. Device stability as a result of post-deposition heat treatment has also been shown to improve with PCE degrading by about 38% after 55 days.The use of interfacial layer is found to play a key part in modifying the solar cell performance; using electron transport layer (ETL) such as aluminium tris(8-hydroxyquinoline) (Alq3) as a solution processable layer has contributed in increasing PCE to 4.25%, while, using PEDOT:PSS as a hole transport layer (HTL) doped with metal salts has significantly contributed in increasing PCE to reach 6.82% in device when PEDOT:PSS was doped with LiCl aqueous solution. Stability study for the device based on HTL has shown degradation in the PCE from 6.82% to around 1% over 96 days. Using ETL and HTL simultaneously in a complete device has shown a further enhanced PCE reaching 7%. In a further study, doping the P3HT:PCBM with the novel ZnPc hybrids (SWCNTs and reduced graphene oxide (rGO) are covalently and non-covalently functionalised to ZnPc) with the weight ratio of (1:0.01) has significantly altered the solar cell device properties. The best performance is based on P3HT:PCBM blended with ZnPc-SWCNTs-co bonded as a ternary active layer demonstrating device PCE of 5.3% compared to a reference device based on bare P3HT:PCBM blend with PCE of 3.46%.

Macular ganglion cell imaging study: glaucoma diagnostic accuracy of spectral-domain optical coherence tomography.

PubMed

Jeoung, Jin Wook; Choi, Yun Jeong; Park, Ki Ho; Kim, Dong Myung

2013-07-01

We evaluated the diagnostic accuracy of macular ganglion cell-inner plexiform layer (GCIPL) measurements using a high-definition optical coherence tomography (Cirrus HD-OCT) ganglion cell analysis algorithm for detecting early and moderate-to-severe glaucoma. Totals of 119 normal subjects and 306 glaucoma patients (164 patients with early glaucoma and 142 with moderate-to-severe glaucoma) were enrolled from the Macular Ganglion Cell Imaging Study. Macular GCIPL, peripapillary retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters were measured in each subject. Areas under the receiver operating characteristic curves (AUROCs) were calculated and compared. Based on the internal normative database, the sensitivity and specificity for detecting early and moderate-to-severe glaucoma were calculated. There was no statistically significant difference between the AUROCs for the best OCT parameters. For detecting early glaucoma, the sensitivity of the Cirrus GCIPL parameters ranged from 26.8% to 73.2% and that of the Cirrus RNFL parameters ranged from 6.1% to 61.6%. For the early glaucoma group, the best parameter from the GCIPL generally had a higher sensitivity than those of the RNFL and ONH parameters with comparable specificity (P < 0.05, McNemar's test). There were no significant differences between the AUROCs for Cirrus GCIPL, RNFL, and ONH parameters, indicating that these maps have similar diagnostic potentials for glaucoma. The minimum GCIPL showed better glaucoma diagnostic performance than the other parameters at comparable specificities. However, other GCIPL parameters showed performances comparable to those of the RNFL parameters.

Neocortical layers I and II of the hedgehog (Erinaceus europaeus). I. Intrinsic organization.

PubMed

Valverde, F; Facal-Valverde, M V

1986-01-01

The intrinsic organization and interlaminar connections in neocortical layers I and II have been studied in adult hedgehogs (Erinaceus europaeus) using the Golgi method. Layer I contains a dense plexus of horizontal fibers, the terminal dendritic bouquets of pyramidal cells of layer II and of underlying layers, and varieties of intrinsic neurons. Four main types of cells were found in layer I. Small horizontal cells represent most probably persisting foetal horizontal cells described for other mammals. Large horizontal cells, tufted cells, and spinous horizontal cells were also found in this layer. Layer II contains primitive pyramidal cells representing the most outstanding feature of the neocortex of the hedgehog. Most pyramidal cells in layer II have two, three or more apical dendrites, richly covered by spines predominating over the basal dendrites. These cells resemble pyramidal cells found in the piriform cortex, hippocampus and other olfactory areas. It is suggested that the presence of these neurons reflects the retention of a primitive character in neocortical evolution. Cells with intrinsic axons were found among pyramidal cells in layer II. These have smooth dendrites penetrating layer I and local axons forming extremely complex terminal arborizations around the bodies and proximal dendritic portions of pyramidal cells. They most probably effect numerous axo-somatic contacts resembling basket cells. The similarity of some axonal terminals with the chandelier type of axonal arborization is discussed. Other varieties of cells located in deep cortical layers and having ascending axons for layers I and II were also studied. It is concluded that the two first neocortical layers represent a level of important integration in this primitive mammal.

Solar cell modules with improved backskin and methods for forming same

DOEpatents

Hanoka, Jack I.

1998-04-21

A laminated solar cell module with a backskin layer that reduces the materials and labor required during the manufacturing process. The solar cell module includes a rigid front support layer formed of light transmitting material having first and second surfaces. A transparent encapsulant layer has a first surface disposed adjacent the second surface of the front support layer. A plurality of interconnected solar cells have a first surface disposed adjacent a second surface of the transparent encapsulant layer. The backskin layer is formed of a thermoplastic olefin, which includes first ionomer, a second ionomer, glass fiber, and carbon black. A first surface of the backskin layer is disposed adjacent a second surface of the interconnected solar cells. The transparent encapsulant layer and the backskin layer, in combination, encapsulate the interconnected solar cells. An end portion of the backskin layer can be wrapped around the edge of the module for contacting the first surface of the front support layer to form an edge seal. A laminated solar cell module with a backskin layer that reduces the materials and labor required during the manufacturing process. The solar cell module includes a rigid front support layer formed of light transmitting material having first and second surfaces. A transparent encapsulant layer has a first surface disposed adjacent the second surface of the front support layer. A plurality of interconnected solar cells have a first surface disposed adjacent a second surface of the transparent encapsulant layer. The backskin layer is formed of a thermoplastic olefin, which includes first ionomer, a second ionomer, glass fiber, and carbon black. A first surface of the backskin layer is disposed adjacent a second surface of the interconnected solar cells. The transparent encapsulant layer and the backskin layer, in combination, encapsulate the interconnected solar cells. An end portion of the backskin layer can be wrapped around the edge of the module for contacting the first surface of the front support layer to form an edge seal.

Hollow spheres of iron carbide nanoparticles encased in graphitic layers as oxygen reduction catalysts.

PubMed

Hu, Yang; Jensen, Jens Oluf; Zhang, Wei; Cleemann, Lars N; Xing, Wei; Bjerrum, Niels J; Li, Qingfeng

2014-04-01

Nonprecious metal catalysts for the oxygen reduction reaction are the ultimate materials and the foremost subject for low-temperature fuel cells. A novel type of catalysts prepared by high-pressure pyrolysis is reported. The catalyst is featured by hollow spherical morphologies consisting of uniform iron carbide (Fe3 C) nanoparticles encased by graphitic layers, with little surface nitrogen or metallic functionalities. In acidic media the outer graphitic layers stabilize the carbide nanoparticles without depriving them of their catalytic activity towards the oxygen reduction reaction (ORR). As a result the catalyst is highly active and stable in both acid and alkaline electrolytes. The synthetic approach, the carbide-based catalyst, the structure of the catalysts, and the proposed mechanism open new avenues for the development of ORR catalysts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Methods for forming particles

DOEpatents

Fox, Robert V.; Zhang, Fengyan; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin

2016-06-21

Single source precursors or pre-copolymers of single source precursors are subjected to microwave radiation to form particles of a I-III-VI.sub.2 material. Such particles may be formed in a wurtzite phase and may be converted to a chalcopyrite phase by, for example, exposure to heat. The particles in the wurtzite phase may have a substantially hexagonal shape that enables stacking into ordered layers. The particles in the wurtzite phase may be mixed with particles in the chalcopyrite phase (i.e., chalcopyrite nanoparticles) that may fill voids within the ordered layers of the particles in the wurtzite phase thus produce films with good coverage. In some embodiments, the methods are used to form layers of semiconductor materials comprising a I-III-VI.sub.2 material. Devices such as, for example, thin-film solar cells may be fabricated using such methods.

Histomorphologic changes of esophageal mucosa in experimental third degree stricture.

PubMed

Shaprynskyi, Volodymyr O; Shaprinskiy, Yevgeniy V; Karyi, Yaroslav V; Lysenko, Serhii A

Nowadays the level of early and late complications after the operations for esophageal corrosive strictures such as esophago-organ anastomotic leak, development of infections, pneumonia, pleural empyema, mediastinitis, peritonitis, postoperative corrosive stricture development etc. remains rather high. Besides, postoperative mortality rate is high as well - 3.5-30 %. For that reason, an experimental model of esophageal stricture was suggested and ultrastructural mucosal changes in the stricture itself were studied to elaborate the unified pathogenic approach in treatment of esophageal stricture and improvement of its results. The aim of our work was to study the dynamics of ultrastructural changes both in normal esophageal walls and in third degree esophageal stricture Materials and Methods: The experiment was carried out on white male rats weighting 250-300 grams, to whom the third degree esophageal stricture model was created. After layer-by-layer incision of anterior abdominal wall abdominal portion of the esophagus was completely ligated (10 rats). In the control group (6 rats) anterior abdominal wall was opened with its subsequent layered closure. The animals were withdrawn from the experiment on the third day by ketamine overdose, and the samples were taken for ultrastructural study. Electron microscopic study of submicroscopic organization of basal, prickle, superficial epithelial cells in stratified non-squamous epithelium, smooth myocytes of muscle plate and contractile elements in esophageal muscular layer was carried out. Nuclear membrane, membranes of mitochondria, endoplasmic reticulum and cytoplasmic Golgi complex were found to be subjected to focal lysis. The third degree esophageal stricture caused destructive lesions in ultrastructural architectonics of stratified non-squamous epithelium cells, smooth myocytes of muscle plate and contractile elements in esophageal muscular layer of rats. Thus, catabolic processes leading to organelle disintegration develop in esophageal cells of rats with third degree stricture.

Osteoblast Differentiation and Bone Matrix Formation In Vivo and In Vitro.

PubMed

Blair, Harry C; Larrouture, Quitterie C; Li, Yanan; Lin, Hang; Beer-Stoltz, Donna; Liu, Li; Tuan, Rocky S; Robinson, Lisa J; Schlesinger, Paul H; Nelson, Deborah J

2017-06-01

We review the characteristics of osteoblast differentiation and bone matrix synthesis. Bone in air breathing vertebrates is a specialized tissue that developmentally replaces simpler solid tissues, usually cartilage. Bone is a living organ bounded by a layer of osteoblasts that, because of transport and compartmentalization requirements, produce bone matrix exclusively as an organized tight epithelium. With matrix growth, osteoblasts are reorganized and incorporated into the matrix as living cells, osteocytes, which communicate with each other and surface epithelium by cell processes within canaliculi in the matrix. The osteoblasts secrete the organic matrix, which are dense collagen layers that alternate parallel and orthogonal to the axis of stress loading. Into this matrix is deposited extremely dense hydroxyapatite-based mineral driven by both active and passive transport and pH control. As the matrix matures, hydroxyapatite microcrystals are organized into a sophisticated composite in the collagen layer by nucleation in the protein lattice. Recent studies on differentiating osteoblast precursors revealed a sophisticated proton export network driving mineralization, a gene expression program organized with the compartmentalization of the osteoblast epithelium that produces the mature bone matrix composite, despite varying serum calcium and phosphate. Key issues not well defined include how new osteoblasts are incorporated in the epithelial layer, replacing those incorporated in the accumulating matrix. Development of bone in vitro is the subject of numerous projects using various matrices and mesenchymal stem cell-derived preparations in bioreactors. These preparations reflect the structure of bone to variable extents, and include cells at many different stages of differentiation. Major challenges are production of bone matrix approaching the in vivo density and support for trabecular bone formation. In vitro differentiation is limited by the organization and density of osteoblasts and by endogenous and exogenous inhibitors.

Osteoblast Differentiation and Bone Matrix Formation In Vivo and In Vitro

PubMed Central

Larrouture, Quitterie C.; Li, Yanan; Lin, Hang; Beer-Stoltz, Donna; Liu, Li; Tuan, Rocky S.; Robinson, Lisa J.; Schlesinger, Paul H.; Nelson, Deborah J.

2017-01-01

We review the characteristics of osteoblast differentiation and bone matrix synthesis. Bone in air breathing vertebrates is a specialized tissue that developmentally replaces simpler solid tissues, usually cartilage. Bone is a living organ bounded by a layer of osteoblasts that, because of transport and compartmentalization requirements, produce bone matrix exclusively as an organized tight epithelium. With matrix growth, osteoblasts are reorganized and incorporated into the matrix as living cells, osteocytes, which communicate with each other and surface epithelium by cell processes within canaliculi in the matrix. The osteoblasts secrete the organic matrix, which are dense collagen layers that alternate parallel and orthogonal to the axis of stress loading. Into this matrix is deposited extremely dense hydroxyapatite-based mineral driven by both active and passive transport and pH control. As the matrix matures, hydroxyapatite microcrystals are organized into a sophisticated composite in the collagen layer by nucleation in the protein lattice. Recent studies on differentiating osteoblast precursors revealed a sophisticated proton export network driving mineralization, a gene expression program organized with the compartmentalization of the osteoblast epithelium that produces the mature bone matrix composite, despite varying serum calcium and phosphate. Key issues not well defined include how new osteoblasts are incorporated in the epithelial layer, replacing those incorporated in the accumulating matrix. Development of bone in vitro is the subject of numerous projects using various matrices and mesenchymal stem cell-derived preparations in bioreactors. These preparations reflect the structure of bone to variable extents, and include cells at many different stages of differentiation. Major challenges are production of bone matrix approaching the in vivo density and support for trabecular bone formation. In vitro differentiation is limited by the organization and density of osteoblasts and by endogenous and exogenous inhibitors. PMID:27846781

Fuel cell system with interconnect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goettler, Richard; Liu, Zhien

The present invention includes a fuel cell system having a plurality of adjacent electrochemical cells formed of an anode layer, a cathode layer spaced apart from the anode layer, and an electrolyte layer disposed between the anode layer and the cathode layer. The fuel cell system also includes at least one interconnect, the interconnect being structured to conduct free electrons between adjacent electrochemical cells. Each interconnect includes a primary conductor embedded within the electrolyte layer and structured to conduct the free electrons.

Fuel cell system with interconnect

DOEpatents

Goettler, Richard; Liu, Zhien

2015-08-11

The present invention includes a fuel cell system having a plurality of adjacent electrochemical cells formed of an anode layer, a cathode layer spaced apart from the anode layer, and an electrolyte layer disposed between the anode layer and the cathode layer. The fuel cell system also includes at least one interconnect, the interconnect being structured to conduct free electrons between adjacent electrochemical cells. Each interconnect includes a primary conductor embedded within the electrolyte layer and structured to conduct the free electrons.

Fuel cell system with interconnect

DOEpatents

Goettler, Richard; Liu, Zhien

2015-03-10

The present invention includes a fuel cell system having a plurality of adjacent electrochemical cells formed of an anode layer, a cathode layer spaced apart from the anode layer, and an electrolyte layer disposed between the anode layer and the cathode layer. The fuel cell system also includes at least one interconnect, the interconnect being structured to conduct free electrons between adjacent electrochemical cells. Each interconnect includes a primary conductor embedded within the electrolyte layer and structured to conduct the free electrons.

Fuel cell system with interconnect

DOEpatents

Liu, Zhien; Goettler, Richard

2015-09-29

The present invention includes a fuel cell system having a plurality of adjacent electrochemical cells formed of an anode layer, a cathode layer spaced apart from the anode layer, and an electrolyte layer disposed between the anode layer and the cathode layer. The fuel cell system also includes at least one interconnect, the interconnect being structured to conduct free electrons between adjacent electrochemical cells. Each interconnect includes a primary conductor embedded within the electrolyte layer and structured to conduct the free electrons.

Electrochemical cells and methods of manufacturing the same

DOEpatents

Bazzarella, Ricardo; Slocum, Alexander H; Doherty, Tristan; Cross, III, James C

2015-11-03

Electrochemical cells and methods of making electrochemical cells are described herein. In some embodiments, an apparatus includes a multi-layer sheet for encasing an electrode material for an electrochemical cell. The multi-layer sheet including an outer layer, an intermediate layer that includes a conductive substrate, and an inner layer disposed on a portion of the conductive substrate. The intermediate layer is disposed between the outer layer and the inner layer. The inner layer defines an opening through which a conductive region of the intermediate layer is exposed such that the electrode material can be electrically connected to the conductive region. Thus, the intermediate layer can serve as a current collector for the electrochemical cell.

Effects of different feeder layers on culture of bovine embryonic stem cell-like cells in vitro.

PubMed

Cong, Shan; Cao, Guifang; Liu, Dongjun

2014-12-01

To find a suitable feeder layer is important for successful culture conditions of bovine embryonic stem cell-like cells. In this study, expression of pluripotency-related genes OCT4, SOX2 and NANOG in bovine embryonic stem cell-like cells on mouse embryonic fibroblast feeder layers at 1-5 passages were monitored in order to identify the possible reason that bovine embryonic stem cell-like cells could not continue growth and passage. Here, we developed two novel feeder layers, mixed embryonic fibroblast feeder layers of mouse and bovine embryonic fibroblast at different ratios and sources including mouse fibroblast cell lines. The bovine embryonic stem cell-like cells generated in our study displayed typical stem cell morphology and expressed specific markers such as OCT4, stage-specific embryonic antigen 1 and 4, alkaline phosphatase, SOX2, and NANOG mRNA levels. When feeder layers and cell growth factors were removed, the bovine embryonic stem cell-like cells formed embryoid bodies in a suspension culture. Furthermore, we compared the expression of the pluripotent markers during bovine embryonic stem cell-like cell in culture on mixed embryonic fibroblast feeder layers, including mouse fibroblast cell lines feeder layers and mouse embryonic fibroblast feeder layers by real-time quantitative polymerase chain reaction. Results suggested that mixed embryonic fibroblast and sources including mouse fibroblast cell lines feeder layers were more suitable for long-term culture and growth of bovine embryonic stem cell-like cells than mouse embryonic fibroblast feeder layers. The findings may provide useful experimental data for the establishment of an appropriate culture system for bovine embryonic stem cell lines.

Macular retinal ganglion cell-inner plexiform layer thickness in patients on hydroxychloroquine therapy.

PubMed

Lee, Min Gyu; Kim, Sang Jin; Ham, Don-Il; Kang, Se Woong; Kee, Changwon; Lee, Jaejoon; Cha, Hoon-Suk; Koh, Eun-Mi

2014-11-25

We evaluated macular ganglion cell-inner plexiform layer (GC-IPL) thickness using spectral-domain optical coherence tomography (SD-OCT) in patients with chronic exposure to hydroxychloroquine (HCQ). This study included 130 subjects, who were divided into three groups: Group 1A, 55 patients with HCQ use ≥5 years; Group 1B, 46 patients with HCQ use <5 years; and Group 2, 29 normal controls. In all patients with exposure to HCQ, fundus examination, automated threshold perimetry, fundus autofluorescence photography, SD-OCT, and GC-IPL thickness measurement using the Cirrus HD-OCT ganglion cell analysis algorithm were performed. Average and minimum macular GC-IPL thickness were compared between subjects groups, and correlations between GC-IPL thickness and duration or total dose of HCQ use were analyzed. Among the 101 patients of Group 1, six patients who showed clinically evident HCQ retinopathy also showed markedly thin macular GC-IPL. In addition, weak but significant negative correlations were observed between the average and minimum GC-IPL thickness of Group 1 patients and cumulative dose of HCQ, even when analyzing without the six patients with HCQ retinopathy. However, when analyzing after exclusion of patients with high cumulative doses (>1000 g), significant correlations were not observed. This study revealed that macular GC-IPL thickness did not show definite correlations with HCQ use. However, some patients, especially with HCQ retinopathy or high cumulative doses, showed thin GC-IPL. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

Improved Visualization of Glaucomatous Retinal Damage Using High-speed Ultrahigh-Resolution Optical Coherence Tomography

PubMed Central

Mumcuoglu, Tarkan; Wollstein, Gadi; Wojtkowski, Maciej; Kagemann, Larry; Ishikawa, Hiroshi; Gabriele, Michelle L.; Srinivasan, Vivek; Fujimoto, James G.; Duker, Jay S.; Schuman, Joel S.

2009-01-01

Purpose To test if improving optical coherence tomography (OCT) resolution and scanning speed improves the visualization of glaucomatous structural changes as compared with conventional OCT. Design Prospective observational case series. Participants Healthy and glaucomatous subjects in various stages of disease. Methods Subjects were scanned at a single visit with commercially available OCT (StratusOCT) and high-speed ultrahigh-resolution (hsUHR) OCT. The prototype hsUHR OCT had an axial resolution of 3.4 μm (3 times higher than StratusOCT), with an A-scan rate of 24 000 hertz (60 times faster than StratusOCT). The fast scanning rate allowed the acquisition of novel scanning patterns such as raster scanning, which provided dense coverage of the retina and optic nerve head. Main Outcome Measures Discrimination of retinal tissue layers and detailed visualization of retinal structures. Results High-speed UHR OCT provided a marked improvement in tissue visualization as compared with StratusOCT. This allowed the identification of numerous retinal layers, including the ganglion cell layer, which is specifically prone to glaucomatous damage. Fast scanning and the enhanced A-scan registration properties of hsUHR OCT provided maps of the macula and optic nerve head with unprecedented detail, including en face OCT fundus images and retinal nerve fiber layer thickness maps. Conclusion High-speed UHR OCT improves visualization of the tissues relevant to the detection and management of glaucoma. PMID:17884170

Method of forming a package for MEMS-based fuel cell

DOEpatents

Morse, Jeffrey D; Jankowski, Alan F

2013-05-21

A MEMS-based fuel cell package and method thereof is disclosed. The fuel cell package comprises seven layers: (1) a sub-package fuel reservoir interface layer, (2) an anode manifold support layer, (3) a fuel/anode manifold and resistive heater layer, (4) a Thick Film Microporous Flow Host Structure layer containing a fuel cell, (5) an air manifold layer, (6) a cathode manifold support structure layer, and (7) a cap. Fuel cell packages with more than one fuel cell are formed by positioning stacks of these layers in series and/or parallel. The fuel cell package materials such as a molded plastic or a ceramic green tape material can be patterned, aligned and stacked to form three dimensional microfluidic channels that provide electrical feedthroughs from various layers which are bonded together and mechanically support a MEMS-based miniature fuel cell. The package incorporates resistive heating elements to control the temperature of the fuel cell stack. The package is fired to form a bond between the layers and one or more microporous flow host structures containing fuel cells are inserted within the Thick Film Microporous Flow Host Structure layer of the package.

Method of forming a package for mems-based fuel cell

DOEpatents

Morse, Jeffrey D.; Jankowski, Alan F.

2004-11-23

A MEMS-based fuel cell package and method thereof is disclosed. The fuel cell package comprises seven layers: (1) a sub-package fuel reservoir interface layer, (2) an anode manifold support layer, (3) a fuel/anode manifold and resistive heater layer, (4) a Thick Film Microporous Flow Host Structure layer containing a fuel cell, (5) an air manifold layer, (6) a cathode manifold support structure layer, and (7) a cap. Fuel cell packages with more than one fuel cell are formed by positioning stacks of these layers in series and/or parallel. The fuel cell package materials such as a molded plastic or a ceramic green tape material can be patterned, aligned and stacked to form three dimensional microfluidic channels that provide electrical feedthroughs from various layers which are bonded together and mechanically support a MEMOS-based miniature fuel cell. The package incorporates resistive heating elements to control the temperature of the fuel cell stack. The package is fired to form a bond between the layers and one or more microporous flow host structures containing fuel cells are inserted within the Thick Film Microporous Flow Host Structure layer of the package.

Solare Cell Roof Tile And Method Of Forming Same

DOEpatents

Hanoka, Jack I.; Real, Markus

1999-11-16

A solar cell roof tile includes a front support layer, a transparent encapsulant layer, a plurality of interconnected solar cells and a backskin layer. The front support layer is formed of light transmitting material and has first and second surfaces. The transparent encapsulant layer is disposed adjacent the second surface of the front support layer. The interconnected solar cells has a first surface disposed adjacent the transparent encapsulant layer. The backskin layer has a first surface disposed adjacent a second surface of the interconnected solar cells, wherein a portion of the backskin layer wraps around and contacts the first surface of the front support layer to form the border region. A portion of the border region has an extended width. The solar cell roof tile may have stand-offs disposed on the extended width border region for providing vertical spacing with respect to an adjacent solar cell roof tile.

Electrochemical cells and methods of manufacturing the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazzarella, Ricardo; Slocum, Alexander H.; Doherty, Tristan

2016-07-26

Electrochemical cells and methods of making electrochemical cells are described herein. In some embodiments, an apparatus includes a multi-layer sheet for encasing an electrode material for an electrochemical cell. The multi-layer sheet including an outer layer, an intermediate layer that includes a conductive substrate, and an inner layer disposed on a portion of the conductive substrate. The intermediate layer is disposed between the outer layer and the inner layer. The inner layer defines an opening through which a conductive region of the intermediate layer is exposed such that the electrode material can be electrically connected to the conductive region. Thus,more » the intermediate layer can serve as a current collector for the electrochemical cell.« less

Progress in developing ultrathin solar cell blanket technology

NASA Technical Reports Server (NTRS)

Patterson, R. E.; Mesch, H. G.; Scott-Monck, J.

1984-01-01

A program was conducted to develop technologies for welding interconnects to three types of 50-micron-thick, 2 by 2-cm solar cells. Parallel-gap resistance welding was used for interconnect attachment. Weld schedules were independently developed for each of the three cell types and were coincidentally identical. Six 48-cell modules were assembled with 50-micron (nominal) thick cells, frosted fused-silica covers, silver-plated Invar interconnectors, and four different substrate designs. Three modules (one for each cell type) have single-layer Kapton (50-micron-thick) substrates. The other three modules each have a different substrate (Kapton-Kevlar-Kapton, Kapton-graphite-Kapton, and Kapton-graphite-aluminum honeycomb-graphite). All six modules were subjected to 4112 thermal cycles from -175 to 65 C (corresponding to over 40 years of simulated geosynchronous orbit thermal cycling) and experienced only negligible electrical degradation (1.1 percent average of six 48-cell modules).

Multijunction photovoltaic device and method of manufacture

DOEpatents

Arya, Rejeewa R.; Catalano, Anthony W.; Bennett, Murray

1995-04-04

A multijunction photovoltaic device includes first, second, and third amorphous silicon p-i-n photovoltaic cells in a stacked arrangement. The intrinsic layers of the second and third cells are formed of a-SiGe alloys with differing ratios of Ge such that the bandgap of the intrinsic layers respectively decrease from the first uppermost cell to the third lowermost cell. An interface layer, composed of a doped silicon compound, is disposed between the two cells and has a lower bandgap than the respective n- and p-type adjacent layers of the first and second cells. The interface layer forms an ohmic contact with the one of the adjacent cell layers of the same conductivity type, and a tunnel junction with the other of the adjacent cell layers.

Plasma-initiated rehydrogenation of amorphous silicon to increase the temperature processing window of silicon heterojunction solar cells

DOE PAGES

Shi, Jianwei; Boccard, Mathieu; Holman, Zachary

2016-07-19

The dehydrogenation of intrinsic hydrogenated amorphous silicon (a-Si:H) at temperatures above approximately 300°C degrades its ability to passivate silicon wafer surfaces. This limits the temperature of post-passivation processing steps during the fabrication of advanced silicon heterojunction or silicon-based tandem solar cells. We demonstrate that a hydrogen plasma can rehydrogenate intrinsic a-Si:H passivation layers that have been dehydrogenated by annealing. The hydrogen plasma treatment fully restores the effective carrier lifetime to several milliseconds in textured crystalline siliconwafers coated with 8-nm-thick intrinsic a-Si:H layers after annealing at temperatures of up to 450°C. Plasma-initiated rehydrogenation also translates to complete solar cells: A silicon heterojunction solar cell subjected to annealing at 450°C (following intrinsic a-Si:H deposition) had an open-circuit voltage of less than 600 mV, but an identical cell that received hydrogen plasma treatment reached a voltagemore » of over 710 mV and an efficiency of over 19%.« less

Plasma-initiated rehydrogenation of amorphous silicon to increase the temperature processing window of silicon heterojunction solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Jianwei; Boccard, Mathieu; Holman, Zachary

The dehydrogenation of intrinsic hydrogenated amorphous silicon (a-Si:H) at temperatures above approximately 300°C degrades its ability to passivate silicon wafer surfaces. This limits the temperature of post-passivation processing steps during the fabrication of advanced silicon heterojunction or silicon-based tandem solar cells. We demonstrate that a hydrogen plasma can rehydrogenate intrinsic a-Si:H passivation layers that have been dehydrogenated by annealing. The hydrogen plasma treatment fully restores the effective carrier lifetime to several milliseconds in textured crystalline siliconwafers coated with 8-nm-thick intrinsic a-Si:H layers after annealing at temperatures of up to 450°C. Plasma-initiated rehydrogenation also translates to complete solar cells: A silicon heterojunction solar cell subjected to annealing at 450°C (following intrinsic a-Si:H deposition) had an open-circuit voltage of less than 600 mV, but an identical cell that received hydrogen plasma treatment reached a voltagemore » of over 710 mV and an efficiency of over 19%.« less

Voltage-matched, monolithic, multi-band-gap devices

DOEpatents

Wanlass, Mark W.; Mascarenhas, Angelo

2006-08-22

Monolithic, tandem, photonic cells include at least a first semiconductor layer and a second semiconductor layer, wherein each semiconductor layer includes an n-type region, a p-type region, and a given band-gap energy. Formed within each semiconductor layer is a sting of electrically connected photonic sub-cells. By carefully selecting the numbers of photonic sub-cells in the first and second layer photonic sub-cell string(s), and by carefully selecting the manner in which the sub-cells in a first and second layer photonic sub-cell string(s) are electrically connected, each of the first and second layer sub-cell strings may be made to achieve one or more substantially identical electrical characteristics.

Voltage-Matched, Monolithic, Multi-Band-Gap Devices

DOEpatents

Wanlass, M. W.; Mascarenhas, A.

2006-08-22

Monolithic, tandem, photonic cells include at least a first semiconductor layer and a second semiconductor layer, wherein each semiconductor layer includes an n-type region, a p-type region, and a given band-gap energy. Formed within each semiconductor layer is a string of electrically connected photonic sub-cells. By carefully selecting the numbers of photonic sub-cells in the first and second layer photonic sub-cell string(s), and by carefully selecting the manner in which the sub-cells in a first and second layer photonic sub-cell string(s) are electrically connected, each of the first and second layer sub-cell strings may be made to achieve one or more substantially identical electrical characteristics.

Deficiency of interstitial cells of Cajal in the small intestine of patients with Crohn's disease.

PubMed

Porcher, Christophe; Baldo, Marjolaine; Henry, Monique; Orsoni, Pierre; Julé, Yvon; Ward, Sean M

2002-01-01

Interstitial cells of Cajal are critical for the generation of electrical slow waves that regulate the phasic contractile activity of the tunica muscularis of the GI tract. Under certain pathophysiological conditions loss of interstitial cells of Cajal may play a role in the generation of certain motility disorders. The aim of the present study was to determine if there is an abnormality in the density or distribution of interstitial cells of Cajal from patients with Crohn's disease. Small intestines from control subjects and patients with Crohn's disease were examined using immunohistochemistry and antibodies against the Kit receptor, which is expressed in interstitial cells of Cajal within the tunica muscularis of the GI tract. The density and distribution of interstitial cells of Cajal were assessed in the longitudinal and circular muscle layers and in the myenteric and deep muscular plexus regions of Crohn's and control tissues. Tissues from Crohn's disease patients showed an almost complete abolition of interstitial cells of Cajal within the longitudinal and circular muscle layers and a significant reduction in numbers at the level of the myenteric and deep muscular plexuses. In tissues from Crohn's disease patients, the density of interstitial cells of Cajal was reduced throughout the tunica muscularis in comparison to control small intestines. The disturbance of intestinal motility that occurs in patients with Crohn's disease may be a consequence of the loss of or defects in specific populations of interstitial cells of Cajal within the tunica muscularis.

Interaction of Vascular Smooth Muscle Cells Under Low Shear Stress

NASA Technical Reports Server (NTRS)

Seidel, Charles L.

1998-01-01

The blood vessel wall consists of three cellular layers, an outer adventitial, a middle medial and an inner intimal layer. When the blood vessel forms in the embryo it begins as a tube composed of a single cell type called endothelial cells. Over time, other cells are recruited from the surrounding tissue to form additional layers on the outer surface of the endothelial tube. The cells that are recruited are called mesenchymal cells. Mesenchymal cells are responsible for the production of connective tissue that holds the blood vessel together and for developing into vascular smooth muscle cells that are responsible for regulating the diameter of the vessel (1) and therefore, blood flow. In a fully developed blood vessel, the endothelial cells make- up the majority of cells in the intimal layer while the mesenchymal cells make-up the majority of cells in the medial and adventitial layers. Within the medial layer of a mature vessel, cells are organized into multiple circular layers of alternating bands of connective tissue and cells. The cell layer is composed of a mixture of mesenchymal cells that have not developed into smooth muscle cells and fully developed smooth muscle cells (2). The assembly and organization of complex tissues is directed in part by a signaling system composed of proteins on the cell surface called adhesion molecules. Adhesion molecules enable cells to recognize each other as well as the composition of the connective tissue in which they reside (3). It was hypothesized that the different cell types that compose the vascular wall possess different adhesion molecules that enable them to recognize each other and through this recognition system, form the complex layered organization of the vascular wall. In other words, the layered organization is an intrinsic property of the cells. If this hypothesis is correct then the different cells that make up the vessel wall, when mixed together, should organize themselves into a layered structure resembling an intact blood vessel. Experiments described below were designed to test this hypothesis.

High-Temperature, Dual-Atmosphere Corrosion of Solid-Oxide Fuel Cell Interconnects

NASA Astrophysics Data System (ADS)

Gannon, Paul; Amendola, Roberta

2012-12-01

High-temperature corrosion of ferritic stainless steel (FSS) surfaces can be accelerated and anomalous when it is simultaneously subjected to different gaseous environments, e.g., when separating fuel (hydrogen) and oxidant (air) streams, in comparison with single-atmosphere exposures, e.g., air only. This so-called "dual-atmosphere" exposure is realized in many energy-conversion systems including turbines, boilers, gasifiers, heat exchangers, and particularly in intermediate temperature (600-800°C) planar solid-oxide fuel cell (SOFC) stacks. It is generally accepted that hydrogen transport through the FSS (plate or tube) and its subsequent integration into the growing air-side surface oxide layer can promote accelerated and anomalous corrosion—relative to single-atmosphere exposure—via defect chemistry changes, such as increased cation vacancy concentrations, decreased oxygen activity, and steam formation within the growing surface oxide layers. Establishment of a continuous and dense surface oxide layer on the fuel side of the FSS can inhibit hydrogen transport and the associated effects on the air side. Minor differences in FSS composition, microstructure, and surface conditions can all have dramatic influences on dual-atmosphere corrosion behaviors. This article reviews high-temperature, dual-atmosphere corrosion phenomena and discusses implications for SOFC stacks, related applications, and future research.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Windisch, C.F. Jr.; Strachan, D.M.; Henager, C.H. Jr.

Cermet anodes were evaluated as nonconsumable substitutes for carbon anodes using a pilot-scale reduction cell at the Reynolds Manufacturing Technology Laboratory. After pilot cell testing, tile anodes were subjected to extensive materials characterization and physical properties measurements at the Pacific Northwest Laboratory. Significant changes in the composition of the cermet anodes were observed including the growth of a reaction layer and penetration of electrolyte deep into the cermet matrix. Fracture strength and toughness were measured as a function of temperature and the ductile-brittle transition wasreduced by 500C following pilot cell testing. These results imply difficulties with anode material and controlmore » of operating conditions in the pilot cell, and suggest that additional development work be performed before the cermet anodes are used in commercial reduction cells. The results also highlight specific fabrication and operational considerations that should be addressed in future testing.« less

Biomask: An Advanced Robotic System for the Real-time, Autonomous Monitoring and Treatment of Facial Burns of Wounded Soldiers

DTIC Science & Technology

2013-04-01

bioreactor systems, a microfluidic -based flexible fluid exchange patch was developed for porcine wound models. A novel design and fabrication process...to be established. 15. SUBJECT TERMS Biomask, burn injury, facial reconstruction, wound-healing, bioreactor, flexible microfluidic , and...and layers of facial skin using different cell types and matrices to produce a reliable, physiologic facial and skin construct to restore functional

Double-layer versus single-layer bone-patellar tendon-bone anterior cruciate ligament reconstruction: a prospective randomized study with 3-year follow-up.

PubMed

Mei, Xiaoliang; Zhang, Zhenxiang; Yang, Jingwen

2016-12-01

To evaluate the clinical results of a randomized controlled trial of single-layer versus double-layer bone-patellar tendon-bone (BPTB) anterior cruciate ligament (ACL) reconstruction. Fifty-eight subjects who underwent primary ACL reconstruction with a BPTB allograft were prospectively randomized into two groups: single-layer reconstruction (n = 31) and double-layer reconstruction (n = 27). The following evaluation methods were used: clinical examination, KT-1000 arthrometer measurement, muscle strength, Tegner activity score, Lysholm score, subjective rating scale regarding patient satisfaction and sports performance level, graft retear, contralateral ACL tear, and additional meniscus surgery. Forty-eight subjects (24 in single-layer group and 24 in double-layer group) who were followed up for 3 years were evaluated. Preoperatively, there were no differences between the groups. At 3-year follow-up, the Lachman and pivot-shift test results were better in the double-layer group (P = 0.019 and P < 0.0001, respectively). KT measurements were better in the double-layer group (mean 2.9 versus 1.5 mm; P = 0.0025). The Tegner score was also better in the double-layer group (P = 0.024). There were no significant differences in range of motion, muscle strength, Lysholm score, subjective rating scale, graft retear, and secondary meniscal tear. In ACL reconstruction, double-layer BPTB reconstruction was significantly better than single-layer reconstruction regarding anterior and rotational stability at 3-year follow-up. The results of KT measurements and the Lachman and pivot-shift tests were significantly better in the double-layer group, whereas there was no difference in the anterior drawer test results. The Tegner score was also better in the double-layer group; however, there were no differences in the other subjective findings.

The effects of the stem cell on ciliary regeneration of injured rabbit sinonasal epithelium.

PubMed

Kavuzlu, Ali; Tatar, Emel Çadallı; Karagöz, Tuğba; Pınarlı, Ferda Alpaslan; Tatar, İlkan; Bayır, Ömer; Korkmaz, Mehmet Hakan

2017-08-01

Defects in mucosal healing after sinonasal surgery cause infection, scar formation causing obstruction, relapse of the disease within a shorter period and revision surgery. The present study aimed to create a functional ciliated epithelium using a stem cell and stem cell sheet of adipose tissue origin and to show such regeneration ultra-structurally on experimentally injured rabbit nasal epithelium. This was an experimental animal study and basic research. A total of 18 white New Zealand rabbits were divided into three groups. The medial wall of the maxillary sinus of the subjects was peeled off bilaterally. No additional procedure was applied to the subjects in Group 1. In Group 2, adipose tissue-derived mesenchymal stem cell was implanted on the wound edges of the subjects. In Group 3, a stem cell sheet of three layers was laid onto the defect area. All subjects were killed after 3 weeks. The presence of the stem cell stained with bromo-deoxyuridine was assessed with a light microscope, whereas cilia density, ciliated orientation and cilia structure were evaluated with a scanning electron microscope. Ciliary densities in Group 2 and Group 3 were statistically superior compared to the control group (p < 0.001, p = 0.007). Cilia morphology in Group 2 and Group 3 was also better than the control group (p < 0.01, p = 0.048). Ciliary orientation in Group 2 was scored highest (p < 0.01). The ratio of BrDu-stained cells was observed to be 27% in Group 3 and 8% in Group 2. Sub-epithelial recovery was observed to be better in Group 3. Adipose tissue-derived mesenchymal stem cell increased the healing of the injured maxillary sinus mucosa of the rabbits in terms of cilia presence, density and morphology regardless of the implementation technique. Level of evidence NA.

Glaucoma-Diagnostic Ability of Ganglion Cell-Inner Plexiform Layer Thickness Difference Across Temporal Raphe in Highly Myopic Eyes.

PubMed

Kim, Young Kook; Yoo, Byeong Wook; Jeoung, Jin Wook; Kim, Hee Chan; Kim, Hae Jin; Park, Ki Ho

2016-11-01

To evaluate the glaucoma-diagnostic ability of the ganglion cell-inner plexiform layer (GCIPL) thickness difference across the temporal raphe in highly myopic eyes. We consecutively enrolled a total of 195 highly myopic eyes (axial length [AL] >26.5 mm) of 195 subjects: 93 glaucoma patients along with and 102 nonglaucomatous subjects. Cirrus high-definition optical coherence tomography (OCT) was employed to scan all of the subjects' macular and optic discs. Using a MATLAB-based customized program (the GCIPL hemifield test), a positive test result was automatically declared if the following two conditions were met: (1) the horizontal line is detected for longer than one-half of the distance from the temporal inner elliptical annulus to the outer elliptical annulus, and (2) the average GCIPL thickness difference within 10 pixels of the reference line, both above and below, is 5 μm or more. The glaucoma-diagnostic ability was computed using the area under the receiver operating characteristic curve (AUC). Among the glaucomatous eyes, GCIPL hemifield test positivity was shown in 92.5% (86 of 93), significantly higher than that for the nonglaucomatous eyes (4.90%, 5 of 102; P <0.001). The value of AUC for the GCIPL hemifield test was excellent (0.938; sensitivity 92.50%, specificity 95.10%) and was the best compared with those for any of OCT parameters. In highly myopic eyes, determination of the presence or absence of GCIPL thickness difference across the temporal raphe via OCT macula scan can be a useful means of distinguishing the glaucomatous damage.

Generation of organized germ layers from a single mouse embryonic stem cell.

PubMed

Poh, Yeh-Chuin; Chen, Junwei; Hong, Ying; Yi, Haiying; Zhang, Shuang; Chen, Junjian; Wu, Douglas C; Wang, Lili; Jia, Qiong; Singh, Rishi; Yao, Wenting; Tan, Youhua; Tajik, Arash; Tanaka, Tetsuya S; Wang, Ning

2014-05-30

Mammalian inner cell mass cells undergo lineage-specific differentiation into germ layers of endoderm, mesoderm and ectoderm during gastrulation. It has been a long-standing challenge in developmental biology to replicate these organized germ layer patterns in culture. Here we present a method of generating organized germ layers from a single mouse embryonic stem cell cultured in a soft fibrin matrix. Spatial organization of germ layers is regulated by cortical tension of the colony, matrix dimensionality and softness, and cell-cell adhesion. Remarkably, anchorage of the embryoid colony from the 3D matrix to collagen-1-coated 2D substrates of ~1 kPa results in self-organization of all three germ layers: ectoderm on the outside layer, mesoderm in the middle and endoderm at the centre of the colony, reminiscent of generalized gastrulating chordate embryos. These results suggest that mechanical forces via cell-matrix and cell-cell interactions are crucial in spatial organization of germ layers during mammalian gastrulation. This new in vitro method could be used to gain insights on the mechanisms responsible for the regulation of germ layer formation.

Perfect absorption in nanotextured thin films via Anderson-localized photon modes

NASA Astrophysics Data System (ADS)

Aeschlimann, Martin; Brixner, Tobias; Differt, Dominik; Heinzmann, Ulrich; Hensen, Matthias; Kramer, Christian; Lükermann, Florian; Melchior, Pascal; Pfeiffer, Walter; Piecuch, Martin; Schneider, Christian; Stiebig, Helmut; Strüber, Christian; Thielen, Philip

2015-10-01

The enhancement of light absorption in absorber layers is crucial in a number of applications, including photovoltaics and thermoelectrics. The efficient use of natural resources and physical constraints such as limited charge extraction in photovoltaic devices require thin but efficient absorbers. Among the many different strategies used, light diffraction and light localization at randomly nanotextured interfaces have been proposed to improve absorption. Although already exploited in commercial devices, the enhancement mechanism for devices with nanotextured interfaces is still subject to debate. Using coherent two-dimensional nanoscopy and coherent light scattering, we demonstrate the existence of localized photonic states in nanotextured amorphous silicon layers as used in commercial thin-film solar cells. Resonant absorption in these states accounts for the enhanced absorption in the long-wavelength cutoff region. Our observations establish that Anderson localization—that is, strong localization—is a highly efficient resonant absorption enhancement mechanism offering interesting opportunities for the design of efficient future absorber layers.

Comparing the Rates of Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Loss in Healthy Eyes and in Glaucoma Eyes.

PubMed

Hammel, Naama; Belghith, Akram; Weinreb, Robert N; Medeiros, Felipe A; Mendoza, Nadia; Zangwill, Linda M

2017-06-01

To compare the rates of circumpapillary retinal nerve fiber layer (RNFL) and macular retinal ganglion cell-inner plexiform layer (GCIPL) change over time in healthy and glaucoma eyes. Cohort study. The rates of circumpapillary RNFL and macular GCIPL loss in 28 healthy subjects and 97 glaucoma subjects from the Diagnostic Innovations in Glaucoma Study (DIGS) were compared using mixed-effects models. The median follow-up time and number of visits were 1.7 years and 6 visits and 3.2 years and 7 visits for healthy and glaucoma eyes, respectively. Significant rates of loss of both global circumpapillary RNFL and average macular GCIPL thickness were detectable in early and moderate glaucoma eyes; in severe glaucoma eyes, rates of average macular GCIPL loss were significant, but rates of global circumpapillary RNFL loss were not. In glaucoma eyes, mean rates of global circumpapillary RNFL thickness change (-0.98 μm/year [95% confidence interval (CI), -1.20 to -0.76]) and normalized global circumpapillary RNFL change (-1.7%/year [95% CI, -2.1 to -1.3]) were significantly faster than average macular GCIPL change (-0.57 μm/year [(95% CI, -0.73 to -0.41]) and normalized macular GCIPL change (-1.3%/year [95% CI, -1.7 to -0.9]). The rates of global and inferior RNFL change were weakly correlated with global and inferior macular GCIPL change (r ranges from 0.16 to 0.23, all P < .05). In this cohort, the rate of circumpapillary RNFL thickness change was faster than macular GCIPL change for glaucoma eyes. Global circumpapillary RNFL thickness loss was detectable in early and moderate glaucoma, and average macular GCIPL thickness loss was detectable in early, moderate, and severe glaucoma, suggesting that structural changes can be detected in severe glaucoma. Copyright © 2017 Elsevier Inc. All rights reserved.

Cooperative vaccinia infection demonstrated at the single-cell level using FluidFM.

PubMed

Stiefel, Philipp; Schmidt, Florian I; Dörig, Pablo; Behr, Pascal; Zambelli, Tomaso; Vorholt, Julia A; Mercer, Jason

2012-08-08

The mechanisms used by viruses to enter and replicate within host cells are subjects of intense investigation. These studies are ultimately aimed at development of new drugs that interfere with these processes. Virus entry and infection are generally monitored by dispensing bulk virus suspensions on layers of cells without accounting for the fate of each virion. Here, we take advantage of the recently developed FluidFM to deposit single vaccinia virions onto individual cells in a controlled manner. While the majority of virions were blocked prior to early gene expression, infection of individual cells increased in a nondeterministic fashion with respect to the number of viruses placed. Microscopic analyses of several stages of the virus lifecycle indicated that this was the result of cooperativity between virions during early stages of infection. These findings highlight the importance of performing controlled virus infection experiments at the single cell level.

Investigation of reliability attributes and accelerated stress factors on terrestrial solar cells

NASA Technical Reports Server (NTRS)

Lathrop, J. W.

1982-01-01

The accelerated stress test results obtained on all terrestrial solar cells since the inception of the program are summarized. Tested cells were grouped according to the method used to form the conductive metallization layer: solder dipped, vacuum deposited, screen printed, and copper plated. Although metallization systems within each group were quite similar, they differed in numerous details according to the procedures employed by each manufacturer. Test results were summarized for all cells according to both electrical degradation and catastrophic mechanical changes. These results indicated a variability within each metallization category which was dependent on the manufacturer. Only one manufacturer was represented in the copper plated category and, although these showed no signs of detrimental copper diffusion during high temperature testing, their metallization was removed easily during high humidity pressure cooker testing. Preliminary testing of encapsulated cells showed no major differences between encapsulated and unencapsulated cells when subjected to accelerated testing.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazzarella, Ricardo; Slocum, Alexander H.; Doherty, Tristan

Electrochemical cells and methods of making electrochemical cells are described herein. In some embodiments, an apparatus includes a multi-layer sheet for encasing an electrode material for an electrochemical cell. The multi-layer sheet including an outer layer, an intermediate layer that includes a conductive substrate, and an inner layer disposed on a portion of the conductive substrate. The intermediate layer is disposed between the outer layer and the inner layer. The inner layer defines an opening through which a conductive region of the intermediate layer is exposed such that the electrode material can be electrically connected to the conductive region. Thus,more » the intermediate layer can serve as a current collector for the electrochemical cell.« less

Temporal dynamics of ovine airway epithelial cell differentiation at an air-liquid interface

PubMed Central

Sutherland, Erin; Berry, Catherine C.; Davies, Robert L.

2017-01-01

The respiratory tract and lungs are subject to diverse pathologies with wide-ranging implications for both human and animal welfare. The development and detailed characterization of cell culture models for studying such forms of disease is of critical importance. In recent years the use of air-liquid interface (ALI)-cultured airway epithelial cells has increased markedly, as this method of culture results in the formation of a highly representative, organotypic in vitro model system. In this study we have expanded on previous knowledge of differentiated ovine tracheal epithelial cells by analysing the progression of differentiation over an extensive time course at an ALI. We observed a pseudo-stratified epithelium with ciliation and a concurrent increase in cell layer thickness from 9 days post-ALI with ciliation approaching a maximum level at day 24. A similar pattern was observed with respect to mucus production with intensely stained PAS-positive cells appearing at day 12. Ultrastructural analysis by SEM confirmed the presence of both ciliated cells and mucus globules on the epithelial surface within this time-frame. Trans-epithelial electrical resistance (TEER) peaked at 1049 Ω × cm2 as the cell layer became confluent, followed by a subsequent reduction as differentiation proceeded and stabilization at ~200 Ω × cm2. Importantly, little deterioration or de-differentiation was observed over the 45 day time-course indicating that the model is suitable for long-term experiments. PMID:28746416

Heterojunction solar cell with passivated emitter surface

DOEpatents

Olson, Jerry M.; Kurtz, Sarah R.

1994-01-01

A high-efficiency heterojunction solar cell wherein a thin emitter layer (preferably Ga.sub.0.52 In.sub.0.48 P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer.

Heterojunction solar cell with passivated emitter surface

DOEpatents

Olson, J.M.; Kurtz, S.R.

1994-05-31

A high-efficiency heterojunction solar cell is described wherein a thin emitter layer (preferably Ga[sub 0.52]In[sub 0.48]P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer. 1 fig.

Thermophotovoltaic in-situ mirror cell

DOEpatents

Campbell, Brian C.

1997-01-01

A photovoltaic cell used in a direct energy conversion generator for converting heat to electricity includes a reflective layer disposed within the cell between the active layers of the cell and the cell substrate. The reflective layer reflects photons of low energy back to a photon producing emitter for reabsorption by the emitter, or reflects photons with energy greater than the cell bandgap back to the cell active layers for conversion into electricity. The reflective layer can comprise a reflective metal such as gold while the substrate can comprise heavily doped silicon or a metal.

An approach for configuring space photovoltaic tandem arrays based on cell layer performance

NASA Technical Reports Server (NTRS)

Flora, C. S.; Dillard, P. A.

1991-01-01

Meeting solar array performance goals of 300 W/Kg requires use of solar cells with orbital efficiencies greater than 20 percent. Only multijunction cells and cell layers operating in tandem produce this required efficiency. An approach for defining solar array design concepts that use tandem cell layers involve the following: transforming cell layer performance at standard test conditions to on-orbit performance; optimizing circuit configuration with tandem cell layers; evaluating circuit sensitivity to cell current mismatch; developing array electrical design around selected circuit; and predicting array orbital performance including seasonal variations.

Resilient protein co-expression network in male orbitofrontal cortex layer 2/3 during human aging.

PubMed

Pabba, Mohan; Scifo, Enzo; Kapadia, Fenika; Nikolova, Yuliya S; Ma, Tianzhou; Mechawar, Naguib; Tseng, George C; Sibille, Etienne

2017-10-01

The orbitofrontal cortex (OFC) is vulnerable to normal and pathologic aging. Currently, layer resolution large-scale proteomic studies describing "normal" age-related alterations at OFC are not available. Here, we performed a large-scale exploratory high-throughput mass spectrometry-based protein analysis on OFC layer 2/3 from 15 "young" (15-43 years) and 18 "old" (62-88 years) human male subjects. We detected 4193 proteins and identified 127 differentially expressed (DE) proteins (p-value ≤0.05; effect size >20%), including 65 up- and 62 downregulated proteins (e.g., GFAP, CALB1). Using a previously described categorization of biological aging based on somatic tissues, that is, peripheral "hallmarks of aging," and considering overlap in protein function, we show the highest representation of altered cell-cell communication (54%), deregulated nutrient sensing (39%), and loss of proteostasis (35%) in the set of OFC layer 2/3 DE proteins. DE proteins also showed a significant association with several neurologic disorders; for example, Alzheimer's disease and schizophrenia. Notably, despite age-related changes in individual protein levels, protein co-expression modules were remarkably conserved across age groups, suggesting robust functional homeostasis. Collectively, these results provide biological insight into aging and associated homeostatic mechanisms that maintain normal brain function with advancing age. Copyright © 2017 Elsevier Inc. All rights reserved.

In Vivo Imaging of the Human Retinal Pigment Epithelial Mosaic Using Adaptive Optics Enhanced Indocyanine Green Ophthalmoscopy

PubMed Central

Tam, Johnny; Liu, Jianfei; Dubra, Alfredo; Fariss, Robert

2016-01-01

Purpose The purpose of this study was to establish that retinal pigment epithelial (RPE) cells take up indocyanine green (ICG) dye following systemic injection and that adaptive optics enhanced indocyanine green ophthalmoscopy (AO-ICG) enables direct visualization of the RPE mosaic in the living human eye. Methods A customized adaptive optics scanning light ophthalmoscope (AOSLO) was used to acquire high-resolution retinal fluorescence images of residual ICG dye in human subjects after intravenous injection at the standard clinical dose. Simultaneously, multimodal AOSLO images were also acquired, which included confocal reflectance, nonconfocal split detection, and darkfield. Imaging was performed in 6 eyes of three healthy subjects with no history of ocular or systemic diseases. In addition, histologic studies in mice were carried out. Results The AO-ICG channel successfully resolved individual RPE cells in human subjects at various time points, including 20 minutes and 2 hours after dye administration. Adaptive optics-ICG images of RPE revealed detail which could be correlated with AO dark-field images of the same cells. Interestingly, there was a marked heterogeneity in the fluorescence of individual RPE cells. Confirmatory histologic studies in mice corroborated the specific uptake of ICG by the RPE layer at a late time point after systemic ICG injection. Conclusions Adaptive optics-enhanced imaging of ICG dye provides a novel way to visualize and assess the RPE mosaic in the living human eye alongside images of the overlying photoreceptors and other cells. PMID:27564519

In Vivo Imaging of the Human Retinal Pigment Epithelial Mosaic Using Adaptive Optics Enhanced Indocyanine Green Ophthalmoscopy.

PubMed

Tam, Johnny; Liu, Jianfei; Dubra, Alfredo; Fariss, Robert

2016-08-01

The purpose of this study was to establish that retinal pigment epithelial (RPE) cells take up indocyanine green (ICG) dye following systemic injection and that adaptive optics enhanced indocyanine green ophthalmoscopy (AO-ICG) enables direct visualization of the RPE mosaic in the living human eye. A customized adaptive optics scanning light ophthalmoscope (AOSLO) was used to acquire high-resolution retinal fluorescence images of residual ICG dye in human subjects after intravenous injection at the standard clinical dose. Simultaneously, multimodal AOSLO images were also acquired, which included confocal reflectance, nonconfocal split detection, and darkfield. Imaging was performed in 6 eyes of three healthy subjects with no history of ocular or systemic diseases. In addition, histologic studies in mice were carried out. The AO-ICG channel successfully resolved individual RPE cells in human subjects at various time points, including 20 minutes and 2 hours after dye administration. Adaptive optics-ICG images of RPE revealed detail which could be correlated with AO dark-field images of the same cells. Interestingly, there was a marked heterogeneity in the fluorescence of individual RPE cells. Confirmatory histologic studies in mice corroborated the specific uptake of ICG by the RPE layer at a late time point after systemic ICG injection. Adaptive optics-enhanced imaging of ICG dye provides a novel way to visualize and assess the RPE mosaic in the living human eye alongside images of the overlying photoreceptors and other cells.

The determination of the real nano-scale sizes of bacteria in chernozem during microbial succession by means of hatching of a soil in aerobic and anaerobic conditions

NASA Astrophysics Data System (ADS)

Gorbacheva, M.

2012-04-01

M.A. Gorbacheva,L.M. Polyanskaya The Faculty of Soil Science, Moscow State University, Leninskie Gory, GSP-1, Moscow,119991,Russia In recent years there's been particular attention paid to the smallest life's forms- bacteria which size can be measured in nanometer. These are the forms of bacteria with diameter of 5-200 nm. Theoretical calculations based on the content of the minimum number of DNA, enzyme, lipids in and ribosome in cells indicates impossibility of existence of a living cells within diameter less than 300 nm. It is theoretically possible for a living cell to exist within possible diameter of approximately 140 nm. Using a fluorescence microscope there's been indicated in a number of samples from lakes, rivers, soil, snow and rain water that 200 nm is the smallest diameter of a living cell. Supposingly, such a small size of bacteria in soil is determined by natural conditions which limit their development by nutritious substances and stress-factors. Rejuvenescence of nanobacteria under unfavourable natural conditions and stress-factors is studied in laboratory environment. The object of the current study has become the samples of typical arable chernozem of the Central Chernozem State Biosphere Reserve in Kursk. The detailed morphological description of the soil profile and its basic analytical characteristics are widely represented in scientific publications. The soil is characterized by a high carbon content which makes up 3,96% ,3,8% , and 2,9% for the upper layers of the A horizon, and 0,79% for the layer of the B horizon. A microbial succession was studied under aerobic and anaerobic conditions by means of experiments with microcosms in upper A horizons and B horizon of a chernozem. The final aim is to identify the cells size of bacteria in aerobic and anaerobic soil conditions in chernozem during the microbial succession, by dampening and application of chitin by means of «cascade filtration» method. The study of the microcosms is important for understanding natural mechanisms in soil and will be useful for the development of new soil models in laboratory. Thus, by means of «cascade filtration» method there've been made some results on true size, quantity and biomass of bacteria. Development of a bacteria in various soil horizons and their layers in aerobic and anaerobic conditions and calculations of biomass of bacteria in upper layer horizon A and lower layer horizon B have also become the subjects of the studies. It was identified that the quantity of bacteria in aerobic conditions increase during the microbial succession while bacteria sized 230 and 380 nm were dominating. In anaerobic conditions the process of connecting cells sized 170 nm and bacteria is observed. Biomass of bacteria is higher in anaerobic conditions in upper layer horizon A because of elevated variety of bacteria. In horizon B in anaerobic conditions it is of maximum because of anaerobic situation in situ. Thus, distribution of bacteria's size depends on aeration of soil. That helps to acknowledge the receipt of theory of a great number of researchers about that fact that the size of bacteria in the soil in anaerobic conditions decrease under stress-factors. This work touches upon such a poorly investigated subject as nanobacteria in the soil. But this knowledge plays a significant role in land reclamation oil-cut and prognostication pollution of the soil by pathogenic bacteria.

Three-dimensional bioprinting of rat embryonic neural cells.

PubMed

Lee, Wonhye; Pinckney, Jason; Lee, Vivian; Lee, Jong-Hwan; Fischer, Krisztina; Polio, Samuel; Park, Je-Kyun; Yoo, Seung-Schik

2009-05-27

We present a direct cell printing technique to pattern neural cells in a three-dimensional (3D) multilayered collagen gel. A layer of collagen precursor was printed to provide a scaffold for the cells, and the rat embryonic neurons and astrocytes were subsequently printed on the layer. A solution of sodium bicarbonate was applied to the cell containing collagen layer as nebulized aerosols, which allowed the gelation of the collagen. This process was repeated layer-by-layer to construct the 3D cell-hydrogel composites. Upon characterizing the relationship between printing resolutions and the growth of printed neural cells, single/multiple layers of neural cell-hydrogel composites were constructed and cultured. The on-demand capability to print neural cells in a multilayered hydrogel scaffold offers flexibility in generating artificial 3D neural tissue composites.

Preservation of Archaeal Surface Layer Structure During Mineralization

NASA Astrophysics Data System (ADS)

Kish, Adrienne; Miot, Jennyfer; Lombard, Carine; Guigner, Jean-Michel; Bernard, Sylvain; Zirah, Séverine; Guyot, François

2016-05-01

Proteinaceous surface layers (S-layers) are highly ordered, crystalline structures commonly found in prokaryotic cell envelopes that augment their structural stability and modify interactions with metals in the environment. While mineral formation associated with S-layers has previously been noted, the mechanisms were unconstrained. Using Sulfolobus acidocaldarius a hyperthermophilic archaeon native to metal-enriched environments and possessing a cell envelope composed only of a S-layer and a lipid cell membrane, we describe a passive process of iron phosphate nucleation and growth within the S-layer of cells and cell-free S-layer “ghosts” during incubation in a Fe-rich medium, independently of metabolic activity. This process followed five steps: (1) initial formation of mineral patches associated with S-layer; (2) patch expansion; (3) patch connection; (4) formation of a continuous mineral encrusted layer at the cell surface; (5) early stages of S-layer fossilization via growth of the extracellular mineralized layer and the mineralization of cytosolic face of the cell membrane. At more advanced stages of encrustation, encrusted outer membrane vesicles are formed, likely in an attempt to remove damaged S-layer proteins. The S-layer structure remains strikingly well preserved even upon the final step of encrustation, offering potential biosignatures to be looked for in the fossil record.

Methods For Improving Polymeric Materials For Use In Solar Cell Applications

DOEpatents

Hanoka, Jack I.

2003-07-01

A method of manufacturing a solar cell module includes the use of low cost polymeric materials with improved mechanical properties. A transparent encapsulant layer is placed adjacent a rear surface of a front support layer. Interconnected solar cells are positioned adjacent a rear surface of the transparent encapsulant layer to form a solar cell assembly. A backskin layer is placed adjacent a rear surface of the solar cell assembly. At least one of the transparent encapsulant layer and the backskin layer are predisposed to electron beam radiation.

Methods For Improving Polymeric Materials For Use In Solar Cell Applications

DOEpatents

Hanoka, Jack I.

2001-11-20

A method of manufacturing a solar cell module includes the use of low cost polymeric materials with improved mechanical properties. A transparent encapsulant layer is placed adjacent a rear surface of a front support layer. Interconnected solar cells are positioned adjacent a rear surface of the transparent encapsulant layer to form a solar cell assembly. A backskin layer is placed adjacent a rear surface of the solar cell assembly. At least one of the transparent encapsulant layer and the backskin layer are predisposed to electron beam radiation.

The Influence of Soft Layer Electrokinetics on Electroporation of Gram-positive Bacteria

NASA Astrophysics Data System (ADS)

Dingari, Naga Neehar; Moran, Jeffrey L.; Garcia, Paulo A.; Buie, Cullen R.

2016-11-01

Bacterial electroporation involves subjecting cells to intense ( 10 kV/cm) electric pulses, to open pores on the cell membrane for intracellular delivery of exogenous molecules. Its high efficiency in genetic transformation makes it an attractive tool for synthetic biology. While mammalian cell electroporation has received extensive theoretical and experimental investigation, bacterial electroporation has received markedly less attention. In this work, we develop a theoretical model of electroporation for gram-positive bacteria, taking into account the effect of the bacterial cell envelope on the cell's response to an electroporation pulse. We model the influence of the cell wall charge on the electrokinetic transport (and hence the pore properties) around the bacterial cell envelope using the Poisson-Nernst-Planck equations. Further, we account for the influence of the cell wall's mechanical elasticity on the pore radius evolution during electroporation, which is typically neglected in mammalian cell electroporation. This yields valuable information about favorable conditions for pore formation and will enable designing optimal platforms for bacteria electroporation.

Can human mesenchymal stem cells survive on a NiTi implant material subjected to cyclic loading?

PubMed

Habijan, T; Glogowski, T; Kühn, S; Pohl, M; Wittsiepe, J; Greulich, C; Eggeler, G; Schildhauer, T A; Köller, M

2011-06-01

Nickel-titanium shape memory alloys (NiTi-SMAs) exhibit mechanical and chemical properties which make them attractive candidate materials for various types of biomedical applications. However, the high nickel content of NiTi-SMAs may result in adverse tissue reactions, especially when they are considered for load-bearing implants. It is generally assumed that a protective titanium oxide layer separates the metallic alloy from its environment and that this explains the good biocompatibility of NiTi. Cyclic loading may result in failure of the protective oxide layer. The scientific objective of this work was to find out whether cyclic dynamic strain, in a range relevant for orthopedic implants, diminishes the biocompatibility of NiTi-SMAs. In order to analyze the biocompatibility of NiTi-SMA surfaces subjected to cyclic loading, NiTi-SMA tensile specimens were preloaded with mesenchymal stem cells, transferred to a sterile cell culture system and fixed to the pull rods of a tensile testing machine. Eighty-six thousand and four hundred strain cycles at 2% pseudoelastic strain were performed for a period of 24 h or 7 days. Cytokines (IL-6, IL-8 and VEGF) and nickel ion release were determined within the cell culture medium. Adherent cells on the tensile specimens were stained with calcein-AM and propidium iodide to determine cell viability. Dynamic loading of the tensile specimens did not influence the viability of adherent human mesenchymal stem cells (hMSCs) after 24 h or 7 days compared with the non-strained control. Dynamic cycles of loading and unloading did not affect nickel ion release from the tensile specimens. The release of IL-6 from hMSCs cultured under dynamic conditions was significantly higher after mechanical load (873 pg ml(-1)) compared with static conditions (323 pg ml(-1)). The present work demonstrates that a new type of mechanical in vitro cell culture experiment can provide information which previously could only be obtained in large animal experiments. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Evaluation of Macular Ganglion Cell-inner Plexiform Layer and Choroid in Psoriasis Patients Using Enhanced Depth Imaging Spectral Domain Optical Coherence Tomography.

PubMed

Ersan, Ismail; Kilic, Sevilay; Arikan, Sedat; Kara, Selcuk; Işik, Selda; Gencer, Baran; Ogretmen, Zerrin

2017-08-01

To evaluate changes in the thickness of the central macula, macular ganglion cell-inner plexiform layer (mGCIPL), and subfoveal choroid in patients with psoriasis using spectral domain optical coherence tomography (SD-OCT). The measurements of macular, mGCIPL thicknesses and subfoveal choroidal thickness (SFCT) obtained by SD-OCT of psoriasis patients (n = 46). These measurements were compared with those of 50 healthy controls. The macular, mGCIPL, and choroidal thicknesses did not differ between the controls and psoriatic subjects (p>0.05). When the patients were divided into two distinct groups, only the SFCT was significantly thicker in the severe psoriasis group compared with the mild psoriasis group (p = 0.003). These findings suggest that choroidal alterations are seen without macular changes in patients with psoriasis. Severe psoriasis appears to be related to increases in SFCT as a consequence of possible inflammatory cascades that are part of the disease's pathogenesis.

Raman mapping of oral buccal mucosa: a spectral histopathology approach

NASA Astrophysics Data System (ADS)

Behl, Isha; Kukreja, Lekha; Deshmukh, Atul; Singh, S. P.; Mamgain, Hitesh; Hole, Arti R.; Krishna, C. Murali

2014-12-01

Oral cancer is one of the most common cancers worldwide. One-fifth of the world's oral cancer subjects are from India and other South Asian countries. The present Raman mapping study was carried out to understand biochemical variations in normal and malignant oral buccal mucosa. Data were acquired using WITec alpha 300R instrument from 10 normal and 10 tumors unstained tissue sections. Raman maps of normal sections could resolve the layers of epithelium, i.e. basal, intermediate, and superficial. Inflammatory, tumor, and stromal regions are distinctly depicted on Raman maps of tumor sections. Mean and difference spectra of basal and inflammatory cells suggest abundance of DNA and carotenoids features. Strong cytochrome bands are observed in intermediate layers of normal and stromal regions of tumor. Epithelium and stromal regions of normal cells are classified by principal component analysis. Classification among cellular components of normal and tumor sections is also observed. Thus, the findings of the study further support the applicability of Raman mapping for providing molecular level insights in normal and malignant conditions.

Three-dimensional baroclinic instability of a Hadley cell for small Richardson number

NASA Technical Reports Server (NTRS)

Antar, B. N.; Fowlis, W. W.

1985-01-01

A three-dimensional, linear stability analysis of a baroclinic flow for Richardson number, Ri, of order unity is presented. The model considered is a thin horizontal, rotating fluid layer which is subjected to horizontal and vertical temperature gradients. The basic state is a Hadley cell which is a solution of the complete set of governing, nonlinear equations and contains both Ekman and thermal boundary layers adjacent to the rigid boundaries; it is given in a closed form. The stability analysis is also based on the complete set of equations; and perturbation possessing zonal, meridional, and vertical structures were considered. Numerical methods were developed for the stability problem which results in a stiff, eighth-order, ordinary differential eigenvalue problem. The previous work on three-dimensional baroclinic instability for small Ri was extended to a more realistic model involving the Prandtl number, sigma, and the Ekman number, E, and to finite growth rates and a wider range of the zonal wavenumber.

Electrical Coupling between the Myenteric Interstitial Cells of Cajal and Adjacent Muscle Layers in the Guinea-Pig Gastric Antrum

PubMed Central

Cousins, H M; Edwards, F R; Hickey, H; Hill, C E; Hirst, G D S

2003-01-01

Intracellular recordings were made from short segments of the muscular wall of the guinea-pig gastric antrum. Preparations were impaled using two independent microelectrodes, one positioned in the circular layer and the other either in the longitudinal layer, in the network of myenteric interstitial cells of Cajal (ICCmy) or in the circular layer. Cells in each layer displayed characteristic patterns of rhythmical activity, with the largest signals being generated by ICCmy. Current pulses injected into the circular muscle layer produced electrotonic potentials in each cell layer, indicating that the layers are electrically interconnected. The amplitudes of these electrotonic potentials were largest in the circular layer and smallest in the longitudinal layer. An analysis of electrical coupling between the three layers suggests that although the cells in each layer are well coupled to neighbouring cells, the coupling between either muscle layer and the network of ICCmy is relatively poor. The electrical connections between ICCmy and the circular layer did not rectify. In parallel immunohistochemical studies, the distribution of the connexins Cx40, Cx43 and Cx45 within the antral wall was determined. Only Cx43 was detected; it was widely distributed on ICCmy and throughout the circular smooth muscle layer, being concentrated around ICCIM, but was less abundant in the circular muscle layer immediately adjacent to ICCmy. Although the electrophysiological studies indicate that smooth muscle cells in the longitudinal muscle layer are electrically coupled to each other, none of the connexins examined were detected in this layer. PMID:12844505

Optimization by simulation of the nature of the buffer, the gap profile of the absorber and the thickness of the various layers in CZTSSe solar cells

NASA Astrophysics Data System (ADS)

Chadel, Meriem; Chadel, Asma; Moustafa Bouzaki, Mohammed; Aillerie, Michel; Benyoucef, Boumediene; Charles, Jean-Pierre

2017-11-01

Performances of ZnO/ZnS/CZTSSe polycrystalline thin film solar cells (Copper Zinc Tin Sulphur Selenium-solar cell) were simulated for different thicknesses of the absorber and ZnS buffer layers. Simulations were performed with SCAPS (Solar Cell Capacitance Simulator) software, starting with actual parameters available from industrial data for commercial cells processing. The influences of the thickness of the various layers in the structure of the solar cell and the gap profile of the CZTSSe absorber layer on the performance of the solar cell were studied in detail. Through considerations of recent works, we discuss possible routes to enhance the performance of CZTSSe solar cells towards a higher efficiency level. Thus, we found that for one specific thickness of the absorber layer, the efficiency of the CZTSSe solar cell can be increased when a ZnS layer replaces the usual CdS buffer layer. On the other hand, the efficiency of the solar cell can be also improved when the absorber layer presents a grad-gap. In this case, the maximum efficiency for the CZTSSe cell was found equal to 13.73%.

SHR overexpression induces the formation of supernumerary cell layers with cortex cell identity in rice.

PubMed

Henry, S; Dievart, A; Divol, F; Pauluzzi, G; Meynard, D; Swarup, R; Wu, S; Gallagher, K L; Périn, C

2017-05-01

The number of root cortex cell layers varies among plants, and many species have several cortical cell layers. We recently demonstrated that the two rice orthologs of the Arabidopsis SHR gene, OsSHR1 and OsSHR2, could complement the A. thaliana shr mutant. Moreover, OsSHR1 and OsSHR2 expression in A. thaliana roots induced the formation of extra root cortical cell layers. In this article, we demonstrate that the overexpression of AtSHR and OsSHR2 in rice roots leads to plants with wide and short roots that contain a high number of extra cortical cell layers. We hypothesize that SHR genes share a conserved function in the control of cortical cell layer division and the number of ground tissue cell layers in land plants. Copyright © 2017 Elsevier Inc. All rights reserved.

Efficient preparation of graphene liquid cell utilizing direct transfer with large-area well-stitched graphene

NASA Astrophysics Data System (ADS)

Sasaki, Yuki; Kitaura, Ryo; Yuk, Jong Min; Zettl, Alex; Shinohara, Hisanori

2016-04-01

By utilizing graphene-sandwiched structures recently developed in this laboratory, we are able to visualize small droplets of liquids in nanometer scale. We have found that small water droplets as small as several tens of nanometers sandwiched by two single-layer graphene are frequently observed by TEM. Due to the electron beam irradiation during the TEM observation, these sandwiched droplets are frequently moving from one place to another and are subjected to create small bubbles inside. The synthesis of a large area single-domain graphene of high-quality is essential to prepare the graphene sandwiched cell which safely encapsulates the droplets in nanometer size.

Layer-by-Layer Bioprinting of Stem Cells for Retinal Tissue Regeneration

DTIC Science & Technology

2015-10-01

AWARD NUMBER: W81XWH-14-1-0522 TITLE: Layer-by-Layer Bioprinting of Stem Cells for Retinal Tissue Regeneration PRINCIPAL INVESTIGATOR...TITLE AND SUBTITLE Layer-by-Layer Bioprinting of Stem Cells for Retinal Tissue Regeneration 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-14-1-0522 5c...bioprinting process using stem cells for retinal tissue regeneration. The LBL nature of the bioprinting process matches nicely with the native

A Population of Progenitor Cells in the Basal and Intermediate Layers of the Murine Bladder Urothelium Contributes to Urothelial Development and Regeneration

PubMed Central

Colopy, Sara A.; Bjorling, Dale E.; Mulligan, William A.; Bushman, Wade

2014-01-01

Background Homeostatic maintenance and repair of the bladder urothelium has been attributed to proliferation of keratin 5-expressing basal cells (K5-BC) with subsequent differentiation into superficial cells. Recent evidence, however, suggests that the intermediate cell layer harbors a population of progenitor cells. We use label-retaining cell (LRC) methodology in conjunction with a clinically relevant model of uropathogenic Escherichia coli (UPEC)-induced injury to characterize urothelial ontogeny during development and in response to diffuse urothelial injury. Results In the developing urothelium, proliferating cells were dispersed throughout the K5-BC and intermediate cells layers, becoming progressively concentrated in the K5-BC layer with age. When 5-bromo-2-deoxyuridine (BrdU) was administered during urothelial development, LRCs in the adult were found within the K5-BC, intermediate, and superficial cell layers, the location dependent upon time of labeling. UPEC inoculation resulted in loss of the superficial cell layer followed by robust proliferation of K5-BCs and intermediate cells. LRCs within the K5-BC and intermediate cell layers proliferated in response to injury. Conclusions Urothelial development and regeneration following injury relies on proliferation of K5-BC and intermediate cells. The existence and proliferation of LRCs within both the K5-BC and intermediate cell layers suggests the presence of two populations of urothelial progenitor cells. PMID:24796293

Developmental patterning of sub-epidermal cells in the outer integument of Arabidopsis seeds

PubMed Central

Fiume, Elisa; Coen, Olivier; Xu, Wenjia; Lepiniec, Loïc

2017-01-01

The seed, the reproductive unit of angiosperms, is generally protected by the seed coat. The seed coat is made of one or two integuments, each comprising two epidermal cells layers and, in some cases, extra sub-epidermal cell layers. The thickness of the seed-coat affects several aspects of seed biology such as dormancy, germination and mortality. In Arabidopsis, the inner integument displays one or two sub-epidermal cell layers that originate from periclinal cell divisions of the innermost epidermal cell layer. By contrast, the outer integument was considered to be two-cell layered. Here, we show that sub-epidermal chalazal cells grow in between the epidermal outer integument cell layers to create an incomplete three-cell layered outer integument. We found that the MADS box transcription factor TRANSPARENT TESTA 16 represses growth of the chalaza and formation of sub-epidermal outer integument cells. Finally, we demonstrate that sub-epidermal cells of the outer and inner integument respond differently to the repressive mechanism mediated by FERTILIZATION INDEPENDENT SEED Polycomb group proteins and to fertilization signals. Our data suggest that integument cell origin rather than sub-epidermal cell position underlies different responses to fertilization. PMID:29141031

Superficial photoluminescence and PV conversion of nanoscale Si-layered systems at 400 nm

NASA Astrophysics Data System (ADS)

Kuznicki, Zbigniew T.; Meyrueis, Patrick; Sarrabayrouse, Gérard; Rousset, Bernard

2006-04-01

A surprising photovoltaic (PV) conversion at 400 nm has been observed in nanoscale Si-layered systems (ns-Si-ls) during spectral response measurements. In conventional solar cells the UV and blue PV conversion may be poor because of the surface recombination within a thin superficial layer. In multi-interface novel devices (MIND) containing ns-Si-ls this conversion is always negligible within an even thicker surface dead zone from which practically no free-carriers can be collected. So the measured 400 nm band PV conversion in MIND cells is totally inconsistent with usually observed effects. Another CE paradox concerns its inversely proportional variation versus incident flux intensity, lower the intensity higher the CE, which value can even exceed unity. This new effect is also localized at the superficial nanostratum and originates from postimplantation defects and nanostructures formed during the implantation process. A similar low energy free-carrier generation has been observed recently in MIND cells with buried ns-Si-ls having a relatively very thin superficial stratum because of an excellent electronic passivation. No available publication mentions such an effect despite extensive investigations on the subject of structural and optical properties of Si nanoparticles, Si nanolayers, new Si-based materials such as semiconductor silicides and the luminescence-center doped Si materials. In this work, the carrier collection properties of the superficial Si nanostratum are reported and discussed in detail in relation to incident flux intensity. An additional low energy generation was observed experimentally. The effect could have capital importance for a breakthrough in the PV conversion efficiency in Si solar cells with nanotransformations.

Heterojunction solar cell

DOEpatents

Olson, Jerry M.

1994-01-01

A high-efficiency single heterojunction solar cell wherein a thin emitter layer (preferably Ga.sub.0.52 In.sub.0.48 P) forms a heterojunction with a GaAs absorber layer. The conversion effiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the emitter layer.

Hybrid window layer for photovoltaic cells

DOEpatents

Deng, Xunming

2010-02-23

A novel photovoltaic solar cell and method of making the same are disclosed. The solar cell includes: at least one absorber layer which could either be a lightly doped layer or an undoped layer, and at least a doped window-layers which comprise at least two sub-window-layers. The first sub-window-layer, which is next to the absorber-layer, is deposited to form desirable junction with the absorber-layer. The second sub-window-layer, which is next to the first sub-window-layer, but not in direct contact with the absorber-layer, is deposited in order to have transmission higher than the first-sub-window-layer.

Hybrid window layer for photovoltaic cells

DOEpatents

Deng, Xunming [Syvania, OH; Liao, Xianbo [Toledo, OH; Du, Wenhui [Toledo, OH

2011-10-04

A novel photovoltaic solar cell and method of making the same are disclosed. The solar cell includes: at least one absorber layer which could either be a lightly doped layer or an undoped layer, and at least a doped window-layers which comprise at least two sub-window-layers. The first sub-window-layer, which is next to the absorber-layer, is deposited to form desirable junction with the absorber-layer. The second sub-window-layer, which is next to the first sub-window-layer, but not in direct contact with the absorber-layer, is deposited in order to have transmission higher than the first-sub-window-layer.

Hybrid window layer for photovoltaic cells

DOEpatents

Deng, Xunming [Sylvania, OH; Liao, Xianbo [Toledo, OH; Du, Wenhui [Toledo, OH

2011-02-01

A novel photovoltaic solar cell and method of making the same are disclosed. The solar cell includes: at least one absorber layer which could either be a lightly doped layer or an undoped layer, and at least a doped window-layers which comprise at least two sub-window-layers. The first sub-window-layer, which is next to the absorber-layer, is deposited to form desirable junction with the absorber-layer. The second sub-window-layer, which is next to the first sub-window-layer, but not in direct contact with the absorber-layer, is deposited in order to have transmission higher than the first-sub-window-layer.

Increased voltage photovoltaic cell

NASA Technical Reports Server (NTRS)

Ross, B.; Bickler, D. B.; Gallagher, B. D. (Inventor)

1985-01-01

A photovoltaic cell, such as a solar cell, is provided which has a higher output voltage than prior cells. The improved cell includes a substrate of doped silicon, a first layer of silicon disposed on the substrate and having opposite doping, and a second layer of silicon carbide disposed on the first layer. The silicon carbide preferably has the same type of doping as the first layer.

Repeatability of Spectral Domain Optical Coherence Tomography Measurements in High Myopia.

PubMed

Rao, Harsha L; Kumar, Addepalli U; Bonala, Sampath R; Yogesh, Kadam; Lakshmi, Bodduluri

2016-05-01

The purpose of this study was to compare the repeatability of spectral domain optical coherence tomography (SDOCT) parameters in high-myopic and emmetropic healthy subjects, and to evaluate the influence of axial length on the repeatability of SDOCT parameters in high myopia. In a prospective study, 93 eyes of 63 high-myopic subjects (spherical refractive error, -6 to -12 D; median age, 25 y) and 28 eyes of 14 emmetropic (spherical refractive error, 0 D; median age, 30 y) subjects underwent optic nerve head, retinal nerve fiber layer (RNFL), and ganglion cell complex imaging with SDOCT. For the repeatability analysis, 31 eyes of 31 high-myopic subjects and 14 eyes of 14 emmetropic subjects underwent 3 repeated scans in the same session. Among the optic nerve head parameters, within-subject coefficient of variation (CVw) measurements of the disc area (0.6% vs. 0.2%), rim area (8.7 vs. 2.8), and rim volume (16.7 vs. 8.9) were significantly larger (worse) in high-myopic compared with the emmetropic subjects. CVw measurements of all RNFL (range, 1.7 to 22.4) and ganglion cell complex (range, 1.8 to 2.5) parameters in high-myopic subjects were comparable to that in emmetropic subjects (2.4 to 24.0 and 1.7 to 2.0, respectively). Axial length significantly affected the CVw of nasal (coefficient, 0.01; P=0.04) and average RNFL (coefficient, 0.004; P=0.001) parameters but not that of the other SDOCT parameters. Repeatabilities of most of the SDOCT parameters in high-myopic subjects were good and comparable to that of emmetropic subjects. This suggests that SDOCT can be useful for following up high-myopic glaucoma patients to detect progression.

Solar cell with silicon oxynitride dielectric layer

DOEpatents

Shepherd, Michael; Smith, David D

2015-04-28

Solar cells with silicon oxynitride dielectric layers and methods of forming silicon oxynitride dielectric layers for solar cell fabrication are described. For example, an emitter region of a solar cell includes a portion of a substrate having a back surface opposite a light receiving surface. A silicon oxynitride (SiO.sub.xN.sub.y, 0

Layer-specific input to distinct cell types in layer 6 of monkey primary visual cortex.

PubMed

Briggs, F; Callaway, E M

2001-05-15

Layer 6 of monkey V1 contains a physiologically and anatomically diverse population of excitatory pyramidal neurons. Distinctive arborization patterns of axons and dendrites within the functionally specialized cortical layers define eight types of layer 6 pyramidal neurons and suggest unique information processing roles for each cell type. To address how input sources contribute to cellular function, we examined the laminar sources of functional excitatory input onto individual layer 6 pyramidal neurons using scanning laser photostimulation. We find that excitatory input sources correlate with cell type. Class I neurons with axonal arbors selectively targeting magnocellular (M) recipient layer 4Calpha receive input from M-dominated layer 4B, whereas class I neurons whose axonal arbors target parvocellular (P) recipient layer 4Cbeta receive input from P-dominated layer 2/3. Surprisingly, these neuronal types do not differ significantly in the inputs they receive directly from layers 4Calpha or 4Cbeta. Class II cells, which lack dense axonal arbors within layer 4C, receive excitatory input from layers targeted by their local axons. Specifically, type IIA cells project axons to and receive input from the deep but not superficial layers. Type IIB neurons project to and receive input from the deepest and most superficial, but not middle layers. Type IIC neurons arborize throughout the cortical layers and tend to receive inputs from all cortical layers. These observations have implications for the functional roles of different layer 6 cell types in visual information processing.

Double-layered cell transfer technology for bone regeneration

PubMed Central

Akazawa, Keiko; Iwasaki, Kengo; Nagata, Mizuki; Yokoyama, Naoki; Ayame, Hirohito; Yamaki, Kazumasa; Tanaka, Yuichi; Honda, Izumi; Morioka, Chikako; Kimura, Tsuyoshi; Komaki, Motohiro; Kishida, Akio; Izumi, Yuichi; Morita, Ikuo

2016-01-01

For cell-based medicine, to mimic in vivo cellular localization, various tissue engineering approaches have been studied to obtain a desirable arrangement of cells on scaffold materials. We have developed a novel method of cell manipulation called “cell transfer technology”, enabling the transfer of cultured cells onto scaffold materials, and controlling cell topology. Here we show that using this technique, two different cell types can be transferred onto a scaffold surface as stable double layers or in patterned arrangements. Various combinations of adherent cells were transferred to a scaffold, amniotic membrane, in overlapping bilayers (double-layered cell transfer), and transferred cells showed stability upon deformations of the material including folding and trimming. Transplantation of mesenchymal stem cells from periodontal ligaments (PDLSC) and osteoblasts, using double-layered cell transfer significantly enhanced bone formation, when compared to single cell type transplantation. Our findings suggest that this double-layer cell transfer is useful to produce a cell transplantation material that can bear two cell layers. Moreover, the transplantation of an amniotic membrane with PDLSCs/osteoblasts by cell transfer technology has therapeutic potential for bone defects. We conclude that cell transfer technology provides a novel and unique cell transplantation method for bone regeneration. PMID:27624174

Highly doped layer for tunnel junctions in solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fetzer, Christopher M.

A highly doped layer for interconnecting tunnel junctions in multijunction solar cells is presented. The highly doped layer is a delta doped layer in one or both layers of a tunnel diode junction used to connect two or more p-on-n or n-on-p solar cells in a multijunction solar cell. A delta doped layer is made by interrupting the epitaxial growth of one of the layers of the tunnel diode, depositing a delta dopant at a concentration substantially greater than the concentration used in growing the layer of the tunnel diode, and then continuing to epitaxially grow the remaining tunnel diode.

Heterojunction solar cell

DOEpatents

Olson, J.M.

1994-08-30

A high-efficiency single heterojunction solar cell is described wherein a thin emitter layer (preferably Ga[sub 0.52]In[sub 0.48]P) forms a heterojunction with a GaAs absorber layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the emitter layer. 1 fig.

Olfactory granule cell development in normal and hyperthyroid rats.

PubMed

Brunjes, P C; Schwark, H D; Greenough, W T

1982-10-01

Dendritic development was examined in olfactory bulbs of both normal 7-, 14-, 21- and 60-day-old rats and littermates treated on postnatal days 1-4 with 1 microgram/g body weight of L-thyroxine sodium. Tissue was processed via the Golgi-Cox technique and subjected to quantitative analyses of mitral and internal layer granule cell development. These populations of granule cells were selected because their pattern of late proliferation suggested potentially greater susceptibility to postnatal hormonal alterations. Although neonatal hyperthyroidism induces widespread acceleration of maturation, including precocious chemosensitivity, granule cell development was unaffected relative to littermate controls. Both normal and hyperthyroid groups exhibited an inverted U-shaped pattern of cellular development, with rapid dendritic dendritic growth and expansion occurring during the earliest ages tested, but with loss of processes and dendritic field size occurring after day 21.

Thin film heterojunction photovoltaic cells and methods of making the same

DOEpatents

Basol, Bulent M.; Tseng, Eric S.; Rod, Robert L.

1983-06-14

A method of fabricating a thin film heterojunction photovoltaic cell which comprises depositing a film of a near intrinsic or n-type semiconductor compound formed of at least one of the metal elements of Class II B of the Periodic Table of Elements and at least tellurium and then heating said film at a temperature between about 250.degree. C. and 500.degree. C. for a time sufficient to convert said film to a suitably low resistivity p-type semiconductor compound. Such film may be deposited initially on the surface of an n-type semiconductor substrate. Alternatively, there may be deposited on the converted film a layer of n-type semiconductor compound different from the film semiconductor compound. The resulting photovoltaic cell exhibits a substantially increased power output over similar cells not subjected to the method of the present invention.

Multiparametric AFM reveals turgor-responsive net-like peptidoglycan architecture in live streptococci

NASA Astrophysics Data System (ADS)

Saar Dover, Ron; Bitler, Arkady; Shimoni, Eyal; Trieu-Cuot, Patrick; Shai, Yechiel

2015-05-01

Cell-wall peptidoglycan (PG) of Gram-positive bacteria is a strong and elastic multi-layer designed to resist turgor pressure and determine the cell shape and growth. Despite its crucial role, its architecture remains largely unknown. Here using high-resolution multiparametric atomic force microscopy (AFM), we studied how the structure and elasticity of PG change when subjected to increasing turgor pressure in live Group B Streptococcus. We show a new net-like arrangement of PG, which stretches and stiffens following osmotic challenge. The same structure also exists in isogenic mutants lacking surface appendages. Cell aging does not alter the elasticity of the cell wall, yet destroys the net architecture and exposes single segmented strands with the same circumferential orientation as predicted for intact glycans. Together, we show a new functional PG architecture in live Gram-positive bacteria.

Effect of duration and severity of migraine on retinal nerve fiber layer, ganglion cell layer, and choroidal thickness.

PubMed

Abdellatif, Mona K; Fouad, Mohamed M

2018-03-01

To investigate the factors in migraine that have the highest significance on retinal and choroidal layers' thickness. Ninety patients with migraine and 40 age-matched healthy participants were enrolled in this observational, cross-sectional study. After full ophthalmological examination, spectral domain-optical coherence tomography was done for all patients measuring the thickness of ganglion cell layer and retinal nerve fiber layer. Enhanced depth imaging technique was used to measure the choroidal thickness. There was significant thinning in the superior and inferior ganglion cell layers, all retinal nerve fiber layer quadrants, and all choroidal quadrants (except for the central subfield) in migraineurs compared to controls. The duration of migraine was significantly correlated with ganglion cell layer, retinal nerve fiber layer, and all choroidal quadrants, while the severity of migraine was significantly correlated with ganglion cell layer and retinal nerve fiber layer only. Multiregression analysis showed that the duration of migraine is the most important determinant factor of the superior retinal nerve fiber layer quadrant (β = -0.375, p = 0.001) and in all the choroidal quadrants (β = -0.531, -0.692, -0.503, -0.461, -0.564, respectively, p  < 0.001), while severity is the most important determinant factor of inferior, nasal, and temporal retinal nerve fiber layer quadrants (β = -0.256, -0.335, -0.308; p  = 0.036, 0.005, 0.009, respectively) and the inferior ganglion cell layer hemisphere (β = -0.377 and p = 0.001). Ganglion cell layer, retinal nerve fiber layer, and choroidal thickness are significantly thinner in patients with migraine. The severity of migraine has more significant influence in the thinning of ganglion cell layer and retinal nerve fiber layer, while the duration of the disease affected the choroidal thickness more.

Fullerene surfactants and their use in polymer solar cells

DOEpatents

Jen, Kwan-Yue; Yip, Hin-Lap; Li, Chang-Zhi

2015-12-15

Fullerene surfactant compounds useful as interfacial layer in polymer solar cells to enhance solar cell efficiency. Polymer solar cell including a fullerene surfactant-containing interfacial layer intermediate cathode and active layer.

The Neuronal Organization of a Unique Cerebellar Specialization: The Valvula Cerebelli of a Mormyrid Fish

PubMed Central

Shi, Zhigang; Zhang, Yueping; Meek, Johannes; Qiao, Jiantian; Han, Victor Z.

2018-01-01

The distal valvula cerebelli is the most prominent part of the mormyrid cerebellum. It is organized in ridges of ganglionic and molecular layers, oriented perpendicular to the granular layer. We have combined intracellular recording and labelling techniques to reveal the cellular morphology of the valvula ridges in slice preparations. We have also locally ejected tracer in slices and in intact animals to examine its input fibers. The palisade dendrites and fine axon arbors of Purkinje cells are oriented in the horizontal plane of the ridge. The dendrites of basal efferent cells and large central cells are confined to the molecular layer, but are not planer. Basal efferent cell axons are thick, and join the basal bundle leaving the cerebellum. Large central cell axons are also thick, and traverse long distances in the transverse plane, with local collaterals in the ganglionic layer. Vertical cells and small central cells also have thick axons with local collaterals. The dendrites of Golgi cells are confined to the molecular layer, but their axon arbors are either confined to the granular layer or proliferate in both the granular and ganglionic layers. Dendrites of deep stellate cells are distributed in the molecular layer, with fine axon arbors in the ganglionic layer. Granule cell axons enter the molecular layer as parallel fibers without bifurcating. Climbing fibers run in the horizontal plane and terminate exclusively in the ganglionic layer. Our results confirm and extend previous studies and suggest a new concept of the circuitry of the mormyrid valvula cerebelli. PMID:18537139

Preparation of ultra-thin and high-quality WO{sub 3} compact layers and comparision of WO{sub 3} and TiO{sub 2} compact layer thickness in planar perovskite solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jincheng; Shi, Chengwu, E-mail: shicw506@foxmail.com; Chen, Junjun

2016-06-15

In this paper, the ultra-thin and high-quality WO{sub 3} compact layers were successfully prepared by spin-coating-pyrolysis method using the tungsten isopropoxide solution in isopropanol. The influence of WO{sub 3} and TiO{sub 2} compact layer thickness on the photovoltaic performance of planar perovskite solar cells was systematically compared, and the interface charge transfer and recombination in planar perovskite solar cells with TiO{sub 2} compact layer was analyzed by electrochemical impedance spectroscopy. The results revealed that the optimum thickness of WO{sub 3} and TiO{sub 2} compact layer was 15 nm and 60 nm. The planar perovskite solar cell with 15 nm WO{submore » 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. - Graphical abstract: The planar perovskite solar cell with 15 nm WO{sub 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. Display Omitted - Highlights: • Preparation of ultra-thin and high-quality WO{sub 3} compact layers. • Perovskite solar cell with 15 nm-thick WO{sub 3} compact layer achieved PCE of 10.14%. • Perovskite solar cell with 60 nm-thick TiO{sub 2} compact layer achieved PCE of 12.64%.« less

Analysis of in situ proliferative activity in oral gingival epithelium in patients with xerostomia.

PubMed

Celenligil-Nazliel, Haviye; Palali, Ali; Ayhan, Ayşe; Ruacan, Sevket

2003-02-01

Sjögren's syndrome is an autoimmune disease characterized by xerostomia and keratoconjunctivitis sicca. The relationship between xero-stomia and proliferative activity in human gingival epithelium is not known. Proliferating cell nuclear antigen (PCNA) is a nuclear protein associated with the cell cycle. Nuclear PCNA immunoreactivity is found in the proliferative compartment of normal tissues. The aims of this study were to evaluate PCNA expression in oral gingival epithelium of healthy and inflamed gingiva obtained from patients with Sjögren's syndrome, and to compare the results to age- and gender-matched subjects with normal salivary function. Eighteen Sjögren's syndrome patients and 28 controls (14 with chronic periodontitis and 14 with no clinical evidence of periodontal disease) were included in the study. Biopsies were obtained from both inflamed and healthy gingiva. The expression of PCNA was evaluated in formalin-fixed, paraffin-embedded gingival samples using an immunoperoxidase technique and PC10 monoclonal antibody to PCNA. PCNA expression was observed both in the basal and suprabasal layers, and was found to be more prominent in the suprabasal layers. Proliferative index (PI) in inflamed gingiva was significantly lower in the Sjögren's syndrome group. However, no significant difference was observed between the study and control groups with respect to PI in healthy gingiva. In both groups, PI was found to be increased due to inflammation. Our data indicate that proliferative activity is observed in the suprabasal layers and, less frequently, in the basal layer. Inflammation caused increased proliferative activity. However, this positive effect of inflammation on epithelial cell proliferation decreased significantly with a lack of saliva. Therefore, it appears that saliva-derived biological mediators may also contribute to increased proliferative activity observed during inflammation.

Material transport in a wind and buoyancy forced mixed layer

NASA Astrophysics Data System (ADS)

Mensa, J. A.; Özgökmen, T.; Poje, A. C.; Imberger, J.

2016-02-01

Flows in the upper ocean mixed layer are responsible for the transport and dispersion of biogeochemical tracers, phytoplankton and buoyant pollutants, such as hydrocarbons from an oil spill. Material dispersion in mixed layer flows subject to diurnal buoyancy forcing and weak winds (|u10|=5ms-1) are investigated using a non-hydrostatic model. Both purely buoyancy-forced and combined wind- and buoyancy-forced flows are sampled using passive tracers, as well as 2D and 3D particles to explore characteristics of horizontal and vertical dispersion. It is found that the surface tracer patterns are determined by the convergence zones created by convection cells within a time scale of just a few hours. For pure convection, the results displayed the classic signature of Rayleigh-Benard cells. When combined with a wind stress, the convective cells become anisotropic in that the along-wind length scale gets much larger than the cross-wind scale. Horizontal relative dispersion computed by sampling the flow fields using both 2D and 3D passive particles is found to be consistent with the Richardson regime. Relative dispersion is an order of magnitude higher and 2D surface releases transition to Richardson regime faster in the wind-forced case. We also show that the buoyancy-forced case results in significantly lower amplitudes of scale-dependent horizontal relative diffusivity, kD(l), than those reported by Okubo (1970), while the wind- and buoyancy forced case shows a good agreement with Okubo's diffusivity amplitude, and scaling consistent with Richardson's 4/3rd law, kD(l) l4/3. The modelling results provide a framework for measuring material dispersion by mixed layer flow in future observational programs.

Material transport in a convective surface mixed layer under weak wind forcing

NASA Astrophysics Data System (ADS)

Mensa, Jean A.; Özgökmen, Tamay M.; Poje, Andrew C.; Imberger, Jörg

2015-12-01

Flows in the upper ocean mixed layer are responsible for the transport and dispersion of biogeochemical tracers, phytoplankton and buoyant pollutants, such as hydrocarbons from an oil spill. Material dispersion in mixed layer flows subject to diurnal buoyancy forcing and weak winds (| u10 | = 5m s-1) are investigated using a non-hydrostatic model. Both purely buoyancy-forced and combined wind- and buoyancy-forced flows are sampled using passive tracers, as well as 2D and 3D particles to explore characteristics of horizontal and vertical dispersion. It is found that the surface tracer patterns are determined by the convergence zones created by convection cells within a time scale of just a few hours. For pure convection, the results displayed the classic signature of Rayleigh-Benard cells. When combined with a wind stress, the convective cells become anisotropic in that the along-wind length scale gets much larger than the cross-wind scale. Horizontal relative dispersion computed by sampling the flow fields using both 2D and 3D passive particles is found to be consistent with the Richardson regime. Relative dispersion is an order of magnitude higher and 2D surface releases transition to Richardson regime faster in the wind-forced case. We also show that the buoyancy-forced case results in significantly lower amplitudes of scale-dependent horizontal relative diffusivity, kD(ℓ), than those reported by Okubo (1970), while the wind- and buoyancy-forced case shows a good agreement with Okubo's diffusivity amplitude, and the scaling is consistent with Richardson's 4/3rd law, kD ∼ ℓ4/3. These modeling results provide a framework for measuring material dispersion by mixed layer flows in future observational programs.

The functional response of bioactive titania-modified three-dimensional Ti-6Al-4V mesh structure toward providing a favorable pathway for intercellular communication and osteoincorporation.

PubMed

Nune, K C; Misra, R D K; Li, S J; Hao, Y L; Zhang, W

2016-10-01

The objective of the study is to fundamentally elucidate the biological response of 3D printed mesh structures subjected to plasma electrolytic oxidation process through the study of osteoblast functions. The cellular activity of plasma electrolytic-oxidized mesh structure was explored in terms of cell-to-cell communication involving proliferation, synthesis of extracellular and intracellular proteins, and mineralization. Upon plasma electrolytic oxidation of the mesh structure, a thin layer of bioactive titania with pore size 1-3 µm was nucleated on the surface. The combination of microporous bioactive titania and interconnected porous architecture provided the desired pathway for supply of nutrients and oxygen to cells and tissue and a favorable osteogenic microenvironment for tissue on-growth and in-growth, in relation to the unmodified mesh structure. The formation of a confluent layer as envisaged via electron microscopy and quantitative assessment of the expression level of proteins (actin, vinculin, and fibronectin) point toward the determining role of surface-modified mesh structure in modulating osteoblasts functions. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2488-2501, 2016. © 2016 Wiley Periodicals, Inc.

Smectic layer instabilities in liquid crystals.

PubMed

Dierking, Ingo; Mitov, Michel; Osipov, Mikhail A

2015-02-07

Scientists aspire to understand the underlying physics behind the formation of instabilities in soft matter and how to manipulate them for diverse investigations, while engineers aim to design materials that inhibit or impede the nucleation and growth of these instabilities in critical applications. The present paper reviews the field-induced rotational instabilities which may occur in chiral smectic liquid-crystalline layers when subjected to an asymmetric electric field. Such instabilities destroy the so-named bookshelf geometry (in which the smectic layers are normal to the cell surfaces) and have a detrimental effect on all applications of ferroelectric liquid crystals as optical materials. The transformation of the bookshelf geometry into horizontal chevron structures (in which each layer is in a V-shaped structure), and the reorientation dynamics of these chevrons, are discussed in details with respect to the electric field conditions, the material properties and the boundary conditions. Particular attention is given to the polymer-stabilisation of smectic phases as a way to forbid the occurrence of instabilities and the decline of related electro-optical performances. It is also shown which benefit may be gained from layer instabilities to enhance the alignment of the liquid-crystalline geometry in practical devices, such as optical recording by ferroelectric liquid crystals. Finally, the theoretical background of layer instabilities is given and discussed in relation to the experimental data.

Multicenter reliability of semiautomatic retinal layer segmentation using OCT

PubMed Central

Oberwahrenbrock, Timm; Traber, Ghislaine L.; Lukas, Sebastian; Gabilondo, Iñigo; Nolan, Rachel; Songster, Christopher; Balk, Lisanne; Petzold, Axel; Paul, Friedemann; Villoslada, Pablo; Brandt, Alexander U.; Green, Ari J.

2018-01-01

Objective To evaluate the inter-rater reliability of semiautomated segmentation of spectral domain optical coherence tomography (OCT) macular volume scans. Methods Macular OCT volume scans of left eyes from 17 subjects (8 patients with MS and 9 healthy controls) were automatically segmented by Heidelberg Eye Explorer (v1.9.3.0) beta-software (Spectralis Viewing Module v6.0.0.7), followed by manual correction by 5 experienced operators from 5 different academic centers. The mean thicknesses within a 6-mm area around the fovea were computed for the retinal nerve fiber layer, ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer, outer plexiform layer (OPL), and outer nuclear layer (ONL). Intraclass correlation coefficients (ICCs) were calculated for mean layer thickness values. Spatial distribution of ICC values for the segmented volume scans was investigated using heat maps. Results Agreement between raters was good (ICC > 0.84) for all retinal layers, particularly inner retinal layers showed excellent agreement across raters (ICC > 0.96). Spatial distribution of ICC showed highest values in the perimacular area, whereas the ICCs were poorer for the foveola and the more peripheral macular area. The automated segmentation of the OPL and ONL required the most correction and showed the least agreement, whereas differences were less prominent for the remaining layers. Conclusions Automated segmentation with manual correction of macular OCT scans is highly reliable when performed by experienced raters and can thus be applied in multicenter settings. Reliability can be improved by restricting analysis to the perimacular area and compound segmentation of GCL and IPL. PMID:29552598

Patterns of synchrony for feed-forward and auto-regulation feed-forward neural networks.

PubMed

Aguiar, Manuela A D; Dias, Ana Paula S; Ferreira, Flora

2017-01-01

We consider feed-forward and auto-regulation feed-forward neural (weighted) coupled cell networks. In feed-forward neural networks, cells are arranged in layers such that the cells of the first layer have empty input set and cells of each other layer receive only inputs from cells of the previous layer. An auto-regulation feed-forward neural coupled cell network is a feed-forward neural network where additionally some cells of the first layer have auto-regulation, that is, they have a self-loop. Given a network structure, a robust pattern of synchrony is a space defined in terms of equalities of cell coordinates that is flow-invariant for any coupled cell system (with additive input structure) associated with the network. In this paper, we describe the robust patterns of synchrony for feed-forward and auto-regulation feed-forward neural networks. Regarding feed-forward neural networks, we show that only cells in the same layer can synchronize. On the other hand, in the presence of auto-regulation, we prove that cells in different layers can synchronize in a robust way and we give a characterization of the possible patterns of synchrony that can occur for auto-regulation feed-forward neural networks.

Multijunction photovoltaic device and fabrication method

DOEpatents

Arya, Rajeewa R.; Catalano, Anthony W.

1993-09-21

A multijunction photovoltaic device includes first and second amorphous silicon PIN photovoltaic cells in a stacked arrangement. An interface layer, composed of a doped silicon compound, is disposed between the two cells and has a lower bandgap than the respective n- and p-type adjacent layers of the first and second cells. The interface layer forms an ohmic contact with the one or the adjacent cell layers of the same conductivity type, and a tunnel junction with the other of the adjacent cell layers. The disclosed device is fabricated by a glow discharge process.

Improved durability of proton exchange membrane fuel cells by introducing Sn (IV) oxide into electrodes using an ion exchange method

NASA Astrophysics Data System (ADS)

Poulsen, M. G.; Larsen, M. J.; Andersen, S. M.

2017-03-01

Electrodes of Proton Exchange Membrane Fuel Cells (PEMFCs), consisting of catalyst-coated gas diffusion layers, were subjected to an optimized ion exchange procedure, in which tin (IV) oxide (SnO2) nanoparticles were introduced into them. Both methanol and sulfuric acid were tested as ion exchange solvents. SnO2 has previously been shown to exhibit radical scavenging abilities towards radicals inside the electrocatalyst layers. Its presence inside the electrodes was confirmed using X-ray photoelectron spectroscopy and X-ray fluorescence. After exposure to an accelerated stress test in a three-electrode setup, the electrodes containing SnO2 were found to have retained approximately 73.0% of their original Pt, while only 53.2% was retained in electrodes treated identically, but without Sn. Similarly, the SnO2-treated electrodes also experienced a smaller loss in electrochemical surface area in comparison to before the accelerated stress test. A membrane electrode assembly (MEA) constructed with a SnO2-containing anode was evaluated over 500 h. The results showed remarkably reduced OCV decay rate and end of test hydrogen crossover compared to the control MEA, indicating that SnO2 aids in impeding membrane thinning and pinhole formation. The results point toward a positive effect of SnO2 on fuel cell durability, by reducing the degradation of the membrane as well as of the ionomer in the electrocatalyst layer.

Fast process flow, on-wafer interconnection and singulation for MEPV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okandan, Murat; Nielson, Gregory N.; Cruz-Campa, Jose Luis

2017-01-31

A method including providing a substrate comprising a device layer on which a plurality of device cells are defined; depositing a first dielectric layer on the device layer and metal interconnect such that the deposited interconnect is electrically connected to at least two of the device cells; depositing a second dielectric layer over the interconnect; and exposing at least one contact point on the interconnect through the second dielectric layer. An apparatus including a substrate having defined thereon a device layer including a plurality of device cells; a first dielectric layer disposed directly on the device layer; a plurality ofmore » metal interconnects, each of which is electrically connected to at least two of the device cells; and a second dielectric layer disposed over the first dielectric layer and over the interconnects, wherein the second dielectric layer is patterned in a positive or negative planar spring pattern.« less

Fast process flow, on-wafer interconnection and singulation for MEPV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okandan, Murat; Nielson, Gregory N.; Cruz-Campa, Jose Luis

2017-08-29

A method including providing a substrate comprising a device layer on which a plurality of device cells are defined; depositing a first dielectric layer on the device layer and metal interconnect such that the deposited interconnect is electrically connected to at least two of the device cells; depositing a second dielectric layer over the interconnect; and exposing at least one contact point on the interconnect through the second dielectric layer. An apparatus including a substrate having defined thereon a device layer including a plurality of device cells; a first dielectric layer disposed directly on the device layer; a plurality ofmore » metal interconnects, each of which is electrically connected to at least two of the device cells; and a second dielectric layer disposed over the first dielectric layer and over the interconnects, wherein the second dielectric layer is patterned in a positive or negative planar spring pattern.« less

Back contact buffer layer for thin-film solar cells

DOEpatents

Compaan, Alvin D.; Plotnikov, Victor V.

2014-09-09

A photovoltaic cell structure is disclosed that includes a buffer/passivation layer at a CdTe/Back contact interface. The buffer/passivation layer is formed from the same material that forms the n-type semiconductor active layer. In one embodiment, the buffer layer and the n-type semiconductor active layer are formed from cadmium sulfide (CdS). A method of forming a photovoltaic cell includes the step of forming the semiconductor active layers and the buffer/passivation layer within the same deposition chamber and using the same material source.

Diagnostic Value of Ganglion Cell-Inner Plexiform Layer Thickness in Glaucoma With Superior or Inferior Visual Hemifield Defects.

PubMed

Kim, Ho Soong; Yang, Heon; Lee, Tae Heon; Lee, Kyung Heon

2016-06-01

To determine the diagnostic value of the ganglion cell-inner plexiform layer (GCIPL) thickness in glaucomatous eyes with superior or inferior visual hemifield defects. Eighty-five patients with glaucoma (42 isolated superior hemifield defects and 43 isolated inferior hemifield defects) and 46 normal subjects were enrolled. All patients underwent Cirrus high-definition optical coherence tomography and standard automated perimetry. The area under the receiver operating characteristic curve (AUC) was calculated to determine the diagnostic ability of the GCIPL and peripapillary retinal nerve fiber layer (pRNFL). In the superior hemifield defect glaucoma group, the best parameters for discriminating normal eyes from glaucomatous eyes were the inferotemporal GCIPL thickness (0.942), inferior quadrant RNFL thickness (0.974), and 7 o'clock sector RNFL thickness (0.999). For diagnosing inferior hemifield defect glaucoma, the AUCs of all GCIPL parameters (0.331 to 0.702) were significantly lower than that of the superior quadrant RNFL thickness (0.866, P<0.05). The diagnostic ability of GCIPL parameters was similar to that of the pRNFL parameters in superior hemifield defect glaucoma. However, the diagnostic performance of the GCIPL parameters was significantly inferior to those of the pRNFL parameters in eyes with inferior hemifield defect glaucoma.

In vitro reconstruction of hybrid vascular tissue. Hierarchic and oriented cell layers.

PubMed

Kanda, K; Matsuda, T; Oka, T

1993-01-01

Hybrid vascular tissue was hierarchically reconstructed in vitro. A hybrid medial layer composed of type I collagen gel, in which SMCs derived from a mongrel dog were embedded, was formed on the inner surface of a compliant porous polyurethane graft (internal diameter = 3 mm). Endothelial cells (ECs) from the same animal were seeded and cultured on the hybrid media to build an intimal layer. Subsequently, hierarchically structured grafts constructed in this manner were subjected to pulsatile flow (flow rate: 8.5 ml/min; frequency: 60 rpm; amplitude: 5% of graft outer diameter) of culture medium (Medium 199 supplemented with 20% fetal calf serum). After stress loading for as long as 10 days, tissues were morphologically investigated with a light microscope and a scanning electron microscope. Inner surfaces of the hybrid tissues were covered with EC monolayers that aligned along the direction of the flow (i.e., longitudinally). However, SMCs beneath the intima aligned in the circumferential direction. These cellular orientations resembled those in native muscular arteries. The pulsatile stress loaded hybrid tissue mimicked native muscular arteries with respect to hierarchic structure and cellular orientation. In vitro mechanical stress loading on a hybrid graft might provide a high degree of integrity in terms of tissue structure that promises high tolerance toward hydrodynamic stress and regulation of vasomotor tone upon implantation.

Method of fabricating a back-contact solar cell and device thereof

DOEpatents

Li, Bo; Smith, David; Cousins, Peter

2014-07-29

Methods of fabricating back-contact solar cells and devices thereof are described. A method of fabricating a back-contact solar cell includes forming an N-type dopant source layer and a P-type dopant source layer above a material layer disposed above a substrate. The N-type dopant source layer is spaced apart from the P-type dopant source layer. The N-type dopant source layer and the P-type dopant source layer are heated. Subsequently, a trench is formed in the material layer, between the N-type and P-type dopant source layers.

Method of fabricating a back-contact solar cell and device thereof

DOEpatents

Li, Bo; Smith, David; Cousins, Peter

2016-08-02

Methods of fabricating back-contact solar cells and devices thereof are described. A method of fabricating a back-contact solar cell includes forming an N-type dopant source layer and a P-type dopant source layer above a material layer disposed above a substrate. The N-type dopant source layer is spaced apart from the P-type dopant source layer. The N-type dopant source layer and the P-type dopant source layer are heated. Subsequently, a trench is formed in the material layer, between the N-type and P-type dopant source layers.

Bulk-heterojunction organic solar cells sandwiched by solution processed molybdenum oxide and titania nanosheet layers

NASA Astrophysics Data System (ADS)

Itoh, Eiji; Goto, Yoshinori; Fukuda, Katsutoshi

2014-02-01

The contributions of ultrathin titania nanosheet (TN) crystallites were studied in both an inverted bulk-heterojunction (BHJ) cell in an indium-tin oxide (ITO)/titania nanosheet (TN)/poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methylester (PCBM) active layer/MoOx/Ag multilayered photovoltaic device and a conventional BHJ cell in ITO/MoOx/P3HT:PCBM active layer/TN/Al multilayered photovoltaic device. The insertion of only one or two layers of poly(diallyldimethylammonium chloride) (PDDA) and TN multilayered film prepared by the layer-by-layer deposition technique effectively decreased the leakage current and increased the open circuit voltage (VOC), fill factor (FF), and power conversion efficiency (η). The conventional cell sandwiched between a solution-processed, partially crystallized molybdenum oxide hole-extracting buffer layer and a TN electron extracting buffer layer showed comparable cell performance to a device sandwiched between vacuum-deposited molybdenum oxide and TN layers, whereas the inverted cell with solution-processed molybdenum oxide showed a poorer performance probably owing to the increment in the leakage current across the film. The abnormal S-shaped curves observed in the inverted BHJ cell above VOC disappeared with the use of a polyfluorene-based cationic semiconducting polymer as a substitute for an insulating PDDA film, resulting in the improved cell performance.

Experimental and numerical studies of natural convection in a Hele-Shaw cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viney, C.E.; Hickox, C.E.; Montoya, P.C.

1982-12-01

The results of an experimental study are reported in which a Hele-Shaw cell was used to simulate natural convection flow in a homogeneous porous region subjected to a horizonal temperature gradient. Measured velocities and photographs of streamline patterns are compared with numerical predictions produced with the finite element computer program, MARIAH. Results of numerical simulations are also reported for Rayleigh-Benard convection in a bottom-heated, horizontal, prous layer. The numerical results are compared with the experimental Hele-Shaw cell results of Hartline and Lister. The comparison between these experimental and numerical studies provides some support for the qualification of MARIAH as amore » general purpose code for the description of natural convection in porous media at low Rayleigh numbers.« less

Inversion layer solar cell fabrication and evaluation

NASA Technical Reports Server (NTRS)

Call, R. L.

1972-01-01

Silicon solar cells with induced junctions were created by forming an inversion layer near the surface of the silicon by supplying a sheet of positive charge above the surface. This charged layer was supplied through three mechanisms: (1) supplying a positive potential to a transparent electrode separated from the silicon surface by a dielectric, (2) contaminating the oxide layer with positive ions, and (3) forming donor surface states that leave a positive charge on the surface. A movable semi-infinite shadow delineated the extent of sensitivity of the cell due to the inversion region. Measurements of the inversion layer cell response to light of different wavelengths indicated it to be more sensitive to the shorter wavelengths of the sun's spectrum than conventional cells. Theory of the conductance of the inversion layer vs. strength of the inversion layer was compared with experiment and found to match. Theoretical determinations of junction depth and inversion layer strength were made as a function of the surface potential for the transparent electrode cell.

Thickness optimization of the ZnO based TCO layer in a CZTSSe solar cell. Evolution of its performance with thickness when external temperature changes.

NASA Astrophysics Data System (ADS)

Chadel, Meriem; Moustafa Bouzaki, Mohammed; Chadel, Asma; Aillerie, Michel; Benyoucef, Boumediene

2017-07-01

The influence of the thickness of a Zinc Oxide (ZnO) transparent conductive oxide (TCO) layer on the performance of the CZTSSe solar cell is shown in detail. In a photovoltaic cell, the thickness of each layer largely influence the performance of the solar cell and optimization of each layer constitutes a complete work. Here, using the Solar Cell Capacitance Simulation (SCAPS) software, we present simulation results obtained in the analyze of the influence of the TCO layer thickness on the performance of a CZTSSe solar cell, starting from performance of a CZTSSe solar cell commercialized in 2014 with an initial efficiency equal to 12.6%. In simulation, the temperature was considered as a functioning parameter and the evolution of tthe performance of the cell for various thickness of the TCO layer when the external temperature changes is simulated and discussed. The best efficiency of the solar cell based in CZTSSe is obtained with a ZnO thickness equal to 50 nm and low temperature. Based on the considered marketed cell, we show a technological possible increase of the global efficiency achieving 13% by optimization of ZnO based TCO layer.

Cu(In,Ga)Se2 Solar Cells with Amorphous In2O3-Based Front Contact Layers.

PubMed

Koida, Takashi; Ueno, Yuko; Nishinaga, Jiro; Higuchi, Hirohumi; Takahashi, Hideki; Iioka, Masayuki; Shibata, Hajime; Niki, Shigeru

2017-09-06

Amorphous (a-) In 2 O 3 -based front contact layers composed of transparent conducting oxide (TCO) and transparent oxide semiconductor (TOS) layers were proved to be effective in enhancing the short-circuit current density (J sc ) of Cu(In,Ga)Se 2 (CIGS) solar cells with a glass/Mo/CIGS/CdS/TOS/TCO structure, while maintaining high fill factor (FF) and open-circuit voltage (V oc ). An n-type a-In-Ga-Zn-O layer was introduced between the CdS and TCO layers. Unlike unintentionally doped ZnO broadly used as TOS layers in CIGS solar cells, the grain-boundary(GB)-free amorphous structure of the a-In-Ga-Zn-O layers allowed high electron mobility with superior control over the carrier density (N). High FF and V oc values were achieved in solar cells containing a-In-Ga-Zn-O layers with N values broadly ranging from 2 × 10 15 to 3 × 10 18 cm -3 . The decrease in FF and V oc produced by the electronic inhomogeneity of solar cells was mitigated by controlling the series resistance within the TOS layer of CIGS solar cells. In addition, a-In 2 O 3 :H and a-In-Zn-O layers exhibited higher electron mobilities than the ZnO:Al layers conventionally used as TCO layers in CIGS solar cells. The In 2 O 3 -based layers exhibited lower free carrier absorption while maintaining similar sheet resistance than ZnO:Al. The TCO and TOS materials and their combinations did not significantly change the V oc of the CIGS solar cells and the mini-modules.

Layer-by-Layer Heparinization of the Cell Surface by Using Heparin-Binding Peptide Functionalized Human Serum Albumin.

PubMed

Song, Guowei; Hu, Yaning; Liu, Yusheng; Jiang, Rui

2018-05-20

Layer-by-layer heparinization of therapeutic cells prior to transplantation is an effective way to inhibit the instant blood-mediated inflammatory reactions (IBMIRs), which are the major cause of early cell graft loss during post-transplantation. Here, a conjugate of heparin-binding peptide (HBP) and human serum albumin (HSA), HBP-HSA, was synthesized by using heterobifunctional crosslinker. After the first heparin layer was coated on human umbilical vein endothelial cells (HUVECs) by means of the HBP-polyethylene glycol-phospholipid conjugate, HBP-HSA and heparin were then applied to the cell surface sequentially to form multiple layers. The immobilization and retention of heparin were analyzed by confocal microscopy and flow cytometry, respectively, and the cytotoxity of HBP-HSA was further evaluated by cell viability assay. Results indicated that heparin was successfully introduced to the cell surface in a layer-by-layer way and retained for at least 24 h, while the cytotoxity of HBP-HSA was negligible at the working concentration. Accordingly, this conjugate provides a promising method for co-immobilization of heparin and HSA to the cell surface under physiological conditions with improved biocompatibility.

Novel approaches for fabrication of thin film layers for solid oxide electrolyte fuel cells

NASA Technical Reports Server (NTRS)

Murugesamoorthi, K. A.; Srinivasan, S.; Cocke, D. L.; Appleby, A. J.

1990-01-01

The main objectives of the SOFC (solid oxide fuel cell) project are to (1) identify viable and cost-effective techniques to prepare cell components for stable MSOFCs (monolithic SOFCs); (2) fabricate half and single cells; and (3) evaluate their performances. The approach used to fabricate stable MSOFCs is as follows: (1) the electrolyte layer is prepared in the form of a honeycomb structure by alloy oxidation and other cell components are deposited on it; (2) the electrolyte and anode layers are deposited on the cathode layer, which has a porous, honeycomb structure; and (3) the electrolyte and cathode layers are deposited on the anode layer. The current status of the project is reported.

Solar cell with back side contacts

DOEpatents

Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J; Wanlass, Mark Woodbury; Clews, Peggy J

2013-12-24

A III-V solar cell is described herein that includes all back side contacts. Additionally, the positive and negative electrical contacts contact compoud semiconductor layers of the solar cell other than the absorbing layer of the solar cell. That is, the positive and negative electrical contacts contact passivating layers of the solar cell.

Multi-junction solar cell device

DOEpatents

Friedman, Daniel J.; Geisz, John F.

2007-12-18

A multi-junction solar cell device (10) is provided. The multi-junction solar cell device (10) comprises either two or three active solar cells connected in series in a monolithic structure. The multi-junction device (10) comprises a bottom active cell (20) having a single-crystal silicon substrate base and an emitter layer (23). The multi-junction device (10) further comprises one or two subsequent active cells each having a base layer (32) and an emitter layer (23) with interconnecting tunnel junctions between each active cell. At least one layer that forms each of the top and middle active cells is composed of a single-crystal III-V semiconductor alloy that is substantially lattice-matched to the silicon substrate (22). The polarity of the active p-n junction cells is either p-on-n or n-on-p. The present invention further includes a method for substantially lattice matching single-crystal III-V semiconductor layers with the silicon substrate (22) by including boron and/or nitrogen in the chemical structure of these layers.

S-layers: principles and applications

PubMed Central

Sleytr, Uwe B; Schuster, Bernhard; Egelseer, Eva-Maria; Pum, Dietmar

2014-01-01

Monomolecular arrays of protein or glycoprotein subunits forming surface layers (S-layers) are one of the most commonly observed prokaryotic cell envelope components. S-layers are generally the most abundantly expressed proteins, have been observed in species of nearly every taxonomical group of walled bacteria, and represent an almost universal feature of archaeal envelopes. The isoporous lattices completely covering the cell surface provide organisms with various selection advantages including functioning as protective coats, molecular sieves and ion traps, as structures involved in surface recognition and cell adhesion, and as antifouling layers. S-layers are also identified to contribute to virulence when present as a structural component of pathogens. In Archaea, most of which possess S-layers as exclusive wall component, they are involved in determining cell shape and cell division. Studies on structure, chemistry, genetics, assembly, function, and evolutionary relationship of S-layers revealed considerable application potential in (nano)biotechnology, biomimetics, biomedicine, and synthetic biology. PMID:24483139

Effect of overnight orthokeratology on conjunctival goblet cells.

PubMed

Carracedo, Gonzalo; Martin-Gil, Alba; Fonseca, Begoña; Pintor, Jesús

2016-08-01

To evaluate the differences between goblet cell density (GCD) and symptomatology after one month of orthokeratology lens wear. A pilot, short-term study was conducted. Twenty-two subjects (29.7±7.0 years old) participated voluntarily in the study. Subjects were divided into two groups: habitual silicone hydrogel contact lens wearers (SiHCLW) and new contact lens wearers (NCLW). Schirmer test, tear break up time (TBUT), Ocular Surface Disease Index (OSDI) questionnaire and conjunctival impression cytology. GCD, mucin cloud height (MCH) and cell layer thickness (CLT) were measured. All measurements were performed before orthokeratology fitting and one month after fitting to assess the evolution of the changes throughout this time. No differences in tear volume and TBUT between groups were found (p>0.05). However, the OSDI score was statistically better after one month of orthokeratology lens wear than the baseline for the SiHCLW group (p=0.03). Regarding the goblet cell analysis, no differences were found in CLT and MCH from the baseline visit to the one month visit for the SiHCLW compared with NCLW groups (p>0.05). At baseline, the GCD in the SiHCLW group were statistically lower than NCLW group (p<0.001). There was a significant increase in GCD after orthokeratology fitting from 121±140cell/mm(2) to 254±130cell/mm(2) (p<0.001) in the SiHCLW group. Orthokeratology improves the dry eye subject symptoms and GCD after one month of wearing in SiHCLW. These results suggest that orthokeratology could be considered a good alternative for silicone hydrogel contact lens discomfort and dryness. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Rapid fabricating technique for multi-layered human hepatic cell sheets by forceful contraction of the fibroblast monolayer.

PubMed

Sakai, Yusuke; Koike, Makiko; Hasegawa, Hideko; Yamanouchi, Kosho; Soyama, Akihiko; Takatsuki, Mitsuhisa; Kuroki, Tamotsu; Ohashi, Kazuo; Okano, Teruo; Eguchi, Susumu

2013-01-01

Cell sheet engineering is attracting attention from investigators in various fields, from basic research scientists to clinicians focused on regenerative medicine. However, hepatocytes have a limited proliferation potential in vitro, and it generally takes a several days to form a sheet morphology and multi-layered sheets. We herein report our rapid and efficient technique for generating multi-layered human hepatic cell (HepaRG® cell) sheets using pre-cultured fibroblast monolayers derived from human skin (TIG-118 cells) as a feeder layer on a temperature-responsive culture dish. Multi-layered TIG-118/HepaRG cell sheets with a thick morphology were harvested on day 4 of culturing HepaRG cells by forceful contraction of the TIG-118 cells, and the resulting sheet could be easily handled. In addition, the human albumin and alpha 1-antitrypsin synthesis activities of TIG-118/HepaRG cells were approximately 1.2 and 1.3 times higher than those of HepaRG cells, respectively. Therefore, this technique is considered to be a promising modality for rapidly fabricating multi-layered human hepatocyte sheets from cells with limited proliferation potential, and the engineered cell sheet could be used for cell transplantation with highly specific functions.

Articles comprising ferritic stainless steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakowski, James M.

An article of manufacture comprises a ferritic stainless steel that includes a near-surface region depleted of silicon relative to a remainder of the ferritic stainless steel. The article has a reduced tendency to form an electrically resistive silica layer including silicon derived from the steel when the article is subjected to high temperature oxidizing conditions. The ferritic stainless steel is selected from the group comprising AISI Type 430 stainless steel, AISI Type 439 stainless steel, AISI Type 441 stainless steel, AISI Type 444 stainless steel, and E-BRITE.RTM. alloy, also known as UNS 44627 stainless steel. In certain embodiments, the articlemore » of manufacture is a fuel cell interconnect for a solid oxide fuel cell.« less

The Transient Intermediate Plexiform Layer, a Plexiform Layer-like Structure Temporarily Existing in the Inner Nuclear Layer in Developing Rat Retina.

PubMed

Park, Hyung Wook; Kim, Hong-Lim; Park, Yong Soo; Kim, In-Beom

2018-02-01

The retina is a highly specialised part of the brain responsible for visual processing. It is well-laminated; three layers containing five different types of neurons are compartmentalised by two synaptic layers. Among the retinal layers, the inner nuclear layer (INL) is composed of horizontal, bipolar, and amacrine cell types. Bipolar cells form one sublayer in the distal half of the IPL, while amacrine cells form another sublayer in the proximal half, without any border-like structure. Here, we report that a plexiform layer-like structure exists temporarily in the border between the bipolar and amacrine sublayers in the INL in the rat retina during retinal development. This transient intermediate plexiform layer (TIPL) appeared at postnatal day (PD) 7 and then disappeared around PD 12. Most apoptotic cells in the INL were found near the TIPL. These results suggest that the TIPL may contribute to the formation of sublayers and the cell number limit in the INL.

Morphological characterization of rat entorhinal neurons in vivo: soma-dendritic structure and axonal domains.

PubMed

Lingenhöhl, K; Finch, D M

1991-01-01

We used in vivo intracellular labeling with horseradish peroxidase in order to study the soma-dendritic morphology and axonal projections of rat entorhinal neurons. The cells responded to hippocampal stimulation with inhibitory postsynaptic potentials, and thus likely received direct or indirect hippocampal input. All cells (n = 24) showed extensive dendritic domains that extended in some cases for more than 1 mm. The dendrites of layer II neurons were largely restricted to layers I and II or layers I-III, while the dendrites of deeper cells could extend through all cortical layers. Computed 3D rotations showed that the basilar dendrites of deep pyramids extended roughly parallel to the cortical layering, and that they were mostly confined to the layer containing the soma and layers immediately adjacent. Total dendritic lengths averaged 9.8 mm +/- 3.8 (SD), and ranged from 5 mm to more than 18 mm. Axonal processes could be visualized in 21 cells. Most of these showed axonal branching within the entorhinal cortex, sometimes extensive. Efferent axonal domains were reconstructed in detail in 3 layer II stellate cells. All 3 projected axons across the subicular complex to the dentate gyrus. One of these cells showed an extensive net-like axonal domain that also projected to several other structures, including the hippocampus proper, subicular complex, and the amygdalo-piriform transition area. The axons of layer III and IV cells projected to the angular bundle, where they continued in a rostral direction. In contrast to the layer II, III and IV cells, no efferent axonal branches leaving the entorhinal cortex could be visualized in 5 layer V neurons. The data indicate that entorhinal neurons can integrate input from a considerable volume of entorhinal cortex by virtue of their extensive dendritic domains, and provide a further basis for specifying the layers in which cells receive synaptic input. The extensive axonal branching pattern seen in most of the cells would support divergent propagation of their activity.

Photovoltaic module and laminate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bunea, Gabriela E.; Kim, Sung Dug; Kavulak, David F.J.

A photovoltaic module is disclosed. The photovoltaic module has a first side directed toward the sun during normal operation and a second, lower side. The photovoltaic module comprises a perimeter frame and a photovoltaic laminate at least partially enclosed by and supported by the perimeter frame. The photovoltaic laminate comprises a transparent cover layer positioned toward the first side of the photovoltaic module, an upper encapsulant layer beneath and adhering to the cover layer, a plurality of photovoltaic solar cells beneath the upper encapsulant layer, the photovoltaic solar cells electrically interconnected, a lower encapsulant layer beneath the plurality of photovoltaicmore » solar cells, the upper and lower encapsulant layers enclosing the plurality of photovoltaic solar cells, and a homogenous rear environmental protection layer, the rear environmental protection layer adhering to the lower encapsulant layer, the rear environmental protection layer exposed to the ambient environment on the second side of the photovoltaic module.« less

Apparatus and process to eliminate diffusional limitations in a membrane biological reactor by pressure cycling

DOEpatents

Efthymiou, George S.; Shuler, Michael L.

1989-08-29

An improved multilayer continuous biological membrane reactor and a process to eliminate diffusional limitations in membrane reactors in achieved by causing a convective flux of nutrient to move into and out of an immobilized biocatalyst cell layer. In a pressure cycled mode, by increasing and decreasing the pressure in the respective layers, the differential pressure between the gaseous layer and the nutrient layer is alternately changed from positive to negative. The intermittent change in pressure differential accelerates the transfer of nutrient from the nutrient layers to the biocatalyst cell layer, the transfer of product from the cell layer to the nutrient layer and the transfer of byproduct gas from the cell layer to the gaseous layer. Such intermittent cycling substantially eliminates mass transfer gradients in diffusion inhibited systems and greatly increases product yield and throughput in both inhibited and noninhibited systems.

Ratiometric analysis of in vivo retinal layer thicknesses in multiple sclerosis

NASA Astrophysics Data System (ADS)

Bhaduri, Basanta; Nolan, Ryan M.; Shelton, Ryan L.; Pilutti, Lara A.; Motl, Robert W.; Boppart, Stephen A.

2016-09-01

We performed ratiometric analysis of retinal optical coherence tomography images for the first time in multiple sclerosis (MS) patients. The ratiometric analysis identified differences in several retinal layer thickness ratios in the cohort of MS subjects without a history of optic neuritis (ON) compared to healthy control (HC) subjects, and there was no difference in standard retinal nerve fiber layer thickness (RNFLT). The difference in such ratios between HC subjects and those with mild MS-disability, without a difference in RNFLT, further suggests the possibility of using layer ratiometric analysis for detecting early retinal changes in MS. Ratiometric analysis may be useful and potentially more sensitive for detecting disease changes in MS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rubin, H.; Bemporad, G.A.

The advanced solar pond (ASP) is characterized by having two thermal layers. The homogeneous thermal layer is adjacent to the pond bottom. On top of this layer a stratified thermal layer is located. One of the major advantages of the solar pond (SP) stems from its capability to store large quantities of thermal energy. In cases of excessive needs for thermal energy, the flow of the thermal layers may be subject to turbulent flow conditions. In this paper the effect of such conditions on transport phenomena in the ASP is analyzed. The analysis indicates that whereas the homogeneous thermal layermore » flows turbulently, the stratified thermal layer may be subject to laminar flow.« less

The retina of the shovel-nosed ray, Rhinobatos batillum (Rhinobatidae): morphology and quantitative analysis of the ganglion, amacrine and bipolar cell populations.

PubMed

Collin, S P

1988-01-01

A light microscopy study of the retina of the shovel-nosed ray, Rhinobatos batillum (Rhinobatidae) has revealed a duplex retina with a rod to cone ratio between 4:1 and 6:1. The inner nuclear layer consists of three layers of large horizontal cells, tightly packed, stellate bipolar cells, and up to three substrata of amacrine cells. The collaterals of the many supporting Müller cells project from the inner to the outer limiting membrane and divide the retina into many subunits. The cells of the ganglion cell layer are distributed into two layers, although a large proportion of ganglion cells are also displaced into the inner plexiform and inner nuclear layers. Topographic analysis of the cells in the ganglion cell layer, inner plexiform and inner nuclear layers reveals a number of regional specializations or "areae centrales". Ganglion cells were retrogradely-labelled with cobalt-lysine from the optic nerve, and three sub-populations of neurons characterized on their soma size and position. Small (20-50 microns2), large (80-300 microns2) and giant (greater than 300 microns2) sub-populations of ganglion cells each revealed distinct retinal specializations with peak densities of 3 x 10(3), 1.25 x 10(3) and 1.57 x 10(3) cells per mm2, respectively. Topographical comparison between Nissl-stained and retrogradely-labelled ganglion cell populations have established that a maximum of 20% in the "area centralis", and 75% in unspecialized, peripheral regions of the retina are non-ganglion cells. Out of a total of 210,566 cells in the ganglion cell layer, 49% were found to be non-ganglion cells. Iso-density contour maps of amacrine and bipolar cell distributions also reveal some specializations. These cell concentrations lie in corresponding regions to areas of increased density in the large and giant ganglion cell populations, suggesting some functional association.

Structure of gels layers with cells

NASA Astrophysics Data System (ADS)

Pokusaev, B. G.; Karlov, S. P.; Vyazmin, A. V.; Nekrasov, D. A.; Zakharov, N. S.; Khramtsov, D. P.; Skladnev, D. A.; Tyupa, D. V.

2017-11-01

The structure of two-layer agarose gels containing yeast cells is investigated experimentally by spectrometry, to shed a light on the theoretical foundations for the development of bioreactors by the method of 3D bioprinting. Due to division, cells overcome the layer of the dispersion phase separating successively applied layers of the agarose gel. However a gel layer of 100 μm thick with a high concentration of silver nanoparticles completely excludes the infiltration of yeast cells through it. A special sort of agarose is suggested where the concentration of silver nanoparticles formed by cells from salt of silver can serve as an indicator of the state of the yeast cells in the volume of the gel.

The gastric mucosal barrier.

PubMed

Clamp, J R; Ene, D

1989-01-01

The gastric mucosal barrier is a complex system made up of submucosal, epithelial and mucus elements. The mucus gel layer is a thick tenacious organized layer adherent to the epithelium. Despite these properties it is composed of more than 95% water, the organization being provided by long interacting glycoprotein molecules (mucus glycoprotein or mucin). These molecules are largely made up of carbohydrate which is present in large numbers of relatively small oligosaccharide units packed around the polypeptide core. This structure provides clues to the nature of the protection afforded by the mucus layer. For example, it is relatively resistant to proteolysis in the gastrointestinal tract; it retains water in an unstirred layer; the tangled glycoproteins exclude large molecules and the carbohydrate of the oligosaccharide units mirror that at the surface of the epithelial cell. Few biochemical studies have been carried out on the effect of ulcer-healing drugs on gastric mucus. Normal subjects were, therefore, given two weeks treatment with cimetidine, carbenoxolone or misoprostol and the secretions aspirated from the unstimulated and pentagastrin-stimulated stomach. The volume of secretion and weight and carbohydrate content of non-diffusable glycoconjugates were determined for each specimen, together with the proportion of high molecular mass mucin and qualitative and quantitative analyses of the glycopolypeptide. There were no significant differences between the results for each drug or without drug. This may be because normal subjects were studied who already have an effective mucosal barrier. In addition, it is likely that the process of mucus biosynthesis and secretion in a healthy individual is relatively resistant to the action of ulcer healing drugs.

The role of apical contractility in determining cell morphology in multilayered epithelial sheets and tubes

NASA Astrophysics Data System (ADS)

Zhen Tan, Rui; Lai, Tanny; Chiam, K.-H.

2017-08-01

A multilayered epithelium is made up of individual cells that are stratified in an orderly fashion, layer by layer. In such tissues, individual cells can adopt a wide range of shapes ranging from columnar to squamous. From histological images, we observe that, in flat epithelia such as the skin, the cells in the top layer are squamous while those in the middle and bottom layers are columnar, whereas in tubular epithelia, the cells in all layers are columnar. We develop a computational model to understand how individual cell shape is governed by the mechanical forces within multilayered flat and curved epithelia. We derive the energy function for an epithelial sheet of cells considering intercellular adhesive and intracellular contractile forces. We determine computationally the cell morphologies that minimize the energy function for a wide range of cellular parameters. Depending on the dominant adhesive and contractile forces, we find four dominant cell morphologies for the multilayered-layered flat sheet and three dominant cell morphologies for the two-layered curved sheet. We study the transitions between the dominant cell morphologies for the two-layered flat sheet and find both continuous and discontinuous transitions and also the presence of multistable states. Matching our computational results with histological images, we conclude that apical contractile forces from the actomyosin belt in the epithelial cells is the dominant force determining cell shape in multilayered epithelia. Our computational model can guide tissue engineers in designing artificial multilayered epithelia, in terms of figuring out the cellular parameters needed to achieve realistic epithelial morphologies.

Wounding coordinately induces cell wall protein, cell cycle and pectin methyl esterase genes involved in tuber closing layer and wound periderm development.

PubMed

Neubauer, Jonathan D; Lulai, Edward C; Thompson, Asunta L; Suttle, Jeffrey C; Bolton, Melvin D

2012-04-15

Little is known about the coordinate induction of genes that may be involved in agriculturally important wound-healing events. In this study, wound-healing events were determined together with wound-induced expression profiles of selected cell cycle, cell wall protein, and pectin methyl esterase genes using two diverse potato genotypes and two harvests (NDTX4271-5R and Russet Burbank tubers; 2008 and 2009 harvests). By 5 d after wounding, the closing layer and a nascent phellogen had formed. Phellogen cell divisions generated phellem layers until cessation of cell division at 28 d after wounding for both genotypes and harvests. Cell cycle genes encoding epidermal growth factor binding protein (StEBP), cyclin-dependent kinase B (StCDKB) and cyclin-dependent kinase regulatory subunit (StCKS1At) were induced by 1 d after wounding; these expressions coordinated with related phellogen formation and the induction and cessation of phellem cell formation. Genes encoding the structural cell wall proteins extensin (StExt1) and extensin-like (StExtlk) were dramatically up-regulated by 1-5 d after wounding, suggesting involvement with closing layer and later phellem cell layer formation. Wounding up-regulated pectin methyl esterase genes (StPME and StPrePME); StPME expression increased during closing layer and phellem cell formation, whereas maximum expression of StPrePME occurred at 5-14 d after wounding, implicating involvement in later modifications for closing layer and phellem cell formation. The coordinate induction and expression profile of StTLRP, a gene encoding a cell wall strengthening "tyrosine-and lysine-rich protein," suggested a role in the formation of the closing layer followed by phellem cell generation and maturation. Collectively, the genes monitored were wound-inducible and their expression profiles markedly coordinated with closing layer formation and the index for phellogen layer meristematic activity during wound periderm development; results were more influenced by harvest than genotype. Importantly, StTLRP was the only gene examined that may be involved in phellogen cell wall thickening after cessation of phellogen cell division. Published by Elsevier GmbH.

p-Type semiconducting nickel oxide as an efficiency-enhancing anodal interfacial layer in bulk heterojunction solar cells

DOEpatents

Irwin, Michael D; Buchholz, Donald B; Marks, Tobin J; Chang, Robert P. H.

2014-11-25

The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode, a p-type semiconductor layer formed on the anode, and an active organic layer formed on the p-type semiconductor layer, where the active organic layer has an electron-donating organic material and an electron-accepting organic material.

The architecture of the avian retina following exposure to chronic 2 G

NASA Technical Reports Server (NTRS)

Orlando, R. G.; Negulesco, J. A.

1980-01-01

Rhode Island Red female chicks at 2 weeks posthatch were subjected, for 7 d, to either earth gravity of 1 G or a 2-G hypergravity environment by chronic whole-body centrifugation. Animals were sacrificed at 3 weeks posthatch and the eyes were enucleated, fixed in 10% BNF, doubly embedded, sectioned at 7-8 microns and routinely processed with H & E for histological examination. Compared to normogravity controls, animal exposure for 1 week to the chronic effects of 2-G resulted in a significantly decreased mean width of the photoreceptor, inner nuclear, and inner plexiform retinal layers. The outer nuclear, outer plexiform, and ganglion cell layers of the retina appeared minimally affected by the hypergravity state since the mean width of these layers showed no noticeable differences from earth gravity control animals. The present anatomic findings suggest a reduction in the detection of motion or rapid changes in illumination by the avian retina when the animal is exposed at a 2-G environment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shum, Andrew D.; Parkinson, Dilworth Y.; Xiao, Xianghui

The performance of polymer-electrolyte fuel cells is heavily dependent on proper management of liquid water. One particular reason is that liquid water can collect in the gas diffusion layers (GDLs) blocking the reactant flow to the catalyst layer. This results in increased mass-transport losses. At higher temperatures, evaporation of water becomes a dominant water-removal mechanism and specifically phase-change-induced (PCI) flow is present due to thermal gradients. This study used synchrotron based micro X-ray computed tomography (CT) to visualize and quantify the water distribution within gas diffusion layers subject to a thermal gradient. Plotting saturation as a function of through-plane distancemore » quantitatively shows water redistribution, where water evaporates at hotter locations and condenses in colder locations. The morphology of the 2 GDLs on the micro-scale, as well as evaporating water clusters, are resolved, indicating that the GDL voids are slightly prolate, whereas water clusters are oblate. From the mean radii of water distributions and visual inspection, it is observed that larger water clusters evaporate faster than smaller ones.« less

Distinct retrosplenial cortex cell populations and their spike dynamics during ketamine-induced unconscious state

PubMed Central

Zhao, Fang; Tsien, Joe Z.

2017-01-01

Ketamine is known to induce psychotic-like symptoms, including delirium and visual hallucinations. It also causes neuronal damage and cell death in the retrosplenial cortex (RSC), an area that is thought to be a part of high visual cortical pathways and at least partially responsible for ketamine’s psychotomimetic activities. However, the basic physiological properties of RSC cells as well as their response to ketamine in vivo remained largely unexplored. Here, we combine a computational method, the Inter-Spike Interval Classification Analysis (ISICA), and in vivo recordings to uncover and profile excitatory cell subtypes within layers 2&3 and 5&6 of the RSC in mice within both conscious, sleep, and ketamine-induced unconscious states. We demonstrate two distinct excitatory principal cell sub-populations, namely, high-bursting excitatory principal cells and low-bursting excitatory principal cells, within layers 2&3, and show that this classification is robust over the conscious states, namely quiet awake, and natural unconscious sleep periods. Similarly, we provide evidence of high-bursting and low-bursting excitatory principal cell sub-populations within layers 5&6 that remained distinct during quiet awake and sleep states. We further examined how these subtypes are dynamically altered by ketamine. During ketamine-induced unconscious state, these distinct excitatory principal cell subtypes in both layer 2&3 and layer 5&6 exhibited distinct dynamics. We also uncovered different dynamics of local field potential under various brain states in layer 2&3 and layer 5&6. Interestingly, ketamine administration induced high gamma oscillations in layer 2&3 of the RSC, but not layer 5&6. Our results show that excitatory principal cells within RSC layers 2&3 and 5&6 contain multiple physiologically distinct sub-populations, and they are differentially affected by ketamine. PMID:29073221

Distinct retrosplenial cortex cell populations and their spike dynamics during ketamine-induced unconscious state.

PubMed

Fox, Grace E; Li, Meng; Zhao, Fang; Tsien, Joe Z

2017-01-01

Ketamine is known to induce psychotic-like symptoms, including delirium and visual hallucinations. It also causes neuronal damage and cell death in the retrosplenial cortex (RSC), an area that is thought to be a part of high visual cortical pathways and at least partially responsible for ketamine's psychotomimetic activities. However, the basic physiological properties of RSC cells as well as their response to ketamine in vivo remained largely unexplored. Here, we combine a computational method, the Inter-Spike Interval Classification Analysis (ISICA), and in vivo recordings to uncover and profile excitatory cell subtypes within layers 2&3 and 5&6 of the RSC in mice within both conscious, sleep, and ketamine-induced unconscious states. We demonstrate two distinct excitatory principal cell sub-populations, namely, high-bursting excitatory principal cells and low-bursting excitatory principal cells, within layers 2&3, and show that this classification is robust over the conscious states, namely quiet awake, and natural unconscious sleep periods. Similarly, we provide evidence of high-bursting and low-bursting excitatory principal cell sub-populations within layers 5&6 that remained distinct during quiet awake and sleep states. We further examined how these subtypes are dynamically altered by ketamine. During ketamine-induced unconscious state, these distinct excitatory principal cell subtypes in both layer 2&3 and layer 5&6 exhibited distinct dynamics. We also uncovered different dynamics of local field potential under various brain states in layer 2&3 and layer 5&6. Interestingly, ketamine administration induced high gamma oscillations in layer 2&3 of the RSC, but not layer 5&6. Our results show that excitatory principal cells within RSC layers 2&3 and 5&6 contain multiple physiologically distinct sub-populations, and they are differentially affected by ketamine.

Apparatus and method for the electrolytic production of metals

DOEpatents

Sadoway, Donald R.

1991-01-01

Improved electrolytic cells and methods for producing metals by electrolytic reduction of a compound dissolved in a molten electrolyte are disclosed. In the improved cells and methods, a protective surface layer is formed upon at least one electrode in the electrolytic reduction cell and, optionally, upon the lining of the cell. This protective surface layer comprises a material that, at the operating conditions of the cell: (a) is not substantially reduced by the metal product; (b) is not substantially reactive with the cell electrolyte to form materials that are reactive with the metal product; and, (c) has an electrochemical potential that is more electronegative than that of the compound undergoing electrolysis to produce the metal product of the cell. The protective surface layer can be formed upon an electrode metal layer comprising a material, the oxide of which also satisfies the protective layer selection criteria. The protective layer material can also be used on the surface of a cell lining.

Developmental patterning of the sub-epidermal integument cell layer in Arabidopsis seeds

PubMed Central

Coen, Olivier; Fiume, Elisa; Xu, Wenjia; De Vos, Delphine; Lu, Jing; Pechoux, Christine; Lepiniec, Loïc

2017-01-01

Angiosperm seed development is a paradigm of tissue cross-talk. Proper seed formation requires spatial and temporal coordination of the fertilization products – embryo and endosperm – and the surrounding seed coat maternal tissue. In early Arabidopsis seed development, all seed integuments were thought to respond homogenously to endosperm growth. Here, we show that the sub-epidermal integument cell layer has a unique developmental program. We characterized the cell patterning of the sub-epidermal integument cell layer, which initiates a previously uncharacterized extra cell layer, and identified TRANSPARENT TESTA 16 and SEEDSTICK MADS box transcription factors as master regulators of its polar development and cell architecture. Our data indicate that the differentiation of the sub-epidermal integument cell layer is insensitive to endosperm growth alone and to the repressive mechanism established by FERTILIZATION INDEPENDENT ENDOSPERM and MULTICOPY SUPPRESSOR OF IRA1 Polycomb group proteins. This work demonstrates the different responses of epidermal and sub-epidermal integument cell layers to fertilization. PMID:28348169

Mathematical modelling of cell layer growth in a hollow fibre bioreactor.

PubMed

Chapman, Lloyd A C; Whiteley, Jonathan P; Byrne, Helen M; Waters, Sarah L; Shipley, Rebecca J

2017-04-07

Generating autologous tissue grafts of a clinically useful volume requires efficient and controlled expansion of cell populations harvested from patients. Hollow fibre bioreactors show promise as cell expansion devices, owing to their potential for scale-up. However, further research is required to establish how to specify appropriate hollow fibre bioreactor operating conditions for expanding different cell types. In this study we develop a simple model for the growth of a cell layer seeded on the outer surface of a single fibre in a perfused hollow fibre bioreactor. Nutrient-rich culture medium is pumped through the fibre lumen and leaves the bioreactor via the lumen outlet or passes through the porous fibre walls and cell layer, and out via ports on the outer wall of the extra-capillary space. Stokes and Darcy equations for fluid flow in the fibre lumen, fibre wall, cell layer and extra-capillary space are coupled to reaction-advection-diffusion equations for oxygen and lactate transport through the bioreactor, and to a simple growth law for the evolution of the free boundary of the cell layer. Cells at the free boundary are assumed to proliferate at a rate that increases with the local oxygen concentration, and to die and detach from the layer if the local fluid shear stress or lactate concentration exceed critical thresholds. We use the model to predict operating conditions that maximise the cell layer growth for different cell types. In particular, we predict the optimal flow rate of culture medium into the fibre lumen and fluid pressure imposed at the lumen outlet for cell types with different oxygen demands and fluid shear stress tolerances, and compare the growth of the cell layer when the exit ports on the outside of the bioreactor are open with that when they are closed. Model simulations reveal that increasing the inlet flow rate and outlet fluid pressure increases oxygen delivery to the cell layer and, therefore, the growth rate of cells that are tolerant to high shear stresses, but may be detrimental for shear-sensitive cells. The cell layer growth rate is predicted to increase, and be less sensitive to the lactate tolerance of the cells, when the exit ports are opened, as the radial flow through the bioreactor is enhanced and the lactate produced by the cells cleared more rapidly from the cell layer. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Fabrication of low-temperature solid oxide fuel cells with a nanothin protective layer by atomic layer deposition

PubMed Central

2013-01-01

Anode aluminum oxide-supported thin-film fuel cells having a sub-500-nm-thick bilayered electrolyte comprising a gadolinium-doped ceria (GDC) layer and an yttria-stabilized zirconia (YSZ) layer were fabricated and electrochemically characterized in order to investigate the effect of the YSZ protective layer. The highly dense and thin YSZ layer acted as a blockage against electron and oxygen permeation between the anode and GDC electrolyte. Dense GDC and YSZ thin films were fabricated using radio frequency sputtering and atomic layer deposition techniques, respectively. The resulting bilayered thin-film fuel cell generated a significantly higher open circuit voltage of approximately 1.07 V compared with a thin-film fuel cell with a single-layered GDC electrolyte (approximately 0.3 V). PMID:23342963

Surface passivation of InP solar cells with InAlAs layers

NASA Technical Reports Server (NTRS)

Jain, Raj K.; Flood, Dennis J.; Landis, Geoffrey A.

1993-01-01

The efficiency of indium phosphide solar cells is limited by high values of surface recombination. The effect of a lattice-matched In(0.52)Al(0.48)As window layer material for InP solar cells, using the numerical code PC-1D is investigated. It was found that the use of InAlAs layer significantly enhances the p(+)n cell efficiency, while no appreciable improvement is seen for n(+)p cells. The conduction band energy discontinuity at the heterojunction helps in improving the surface recombination. An optimally designed InP cell efficiency improves from 15.4 percent to 23 percent AMO for a 10 nm thick InAlAs layer. The efficiency improvement reduces with increase in InAlAs layer thickness, due to light absorption in the window layer.

Interdigitated photovoltaic power conversion device

DOEpatents

Ward, James Scott; Wanlass, Mark Woodbury; Gessert, Timothy Arthur

1999-01-01

A photovoltaic power conversion device has a top surface adapted to receive impinging radiation. The device includes at least two adjacent, serially connected cells. Each cell includes a semi-insulating substrate and a lateral conductivity layer of a first doped electrical conductivity disposed on the substrate. A base layer is disposed on the lateral conductivity layer and has the same electrical charge conductivity thereof. An emitter layer of a second doped electrical conductivity of opposite electrical charge is disposed on the base layer and forms a p-n junction therebetween. A plurality of spaced channels are formed in the emitter and base layers to expose the lateral conductivity layer at the bottoms thereof. A front contact grid is positioned on the top surface of the emitter layer of each cell. A first current collector is positioned along one outside edge of at least one first cell. A back contact grid is positioned in the channels at the top surface of the device for engagement with the lateral conductivity layer. A second current collector is positioned along at least one outside edge of at least one oppositely disposed second cell. Finally, an interdigitation mechanism is provided for serially connecting the front contact grid of one cell to the back contact grid of an adjacent cell at the top surface of the device.

Interdigitated photovoltaic power conversion device

DOEpatents

Ward, J.S.; Wanlass, M.W.; Gessert, T.A.

1999-04-27

A photovoltaic power conversion device has a top surface adapted to receive impinging radiation. The device includes at least two adjacent, serially connected cells. Each cell includes a semi-insulating substrate and a lateral conductivity layer of a first doped electrical conductivity disposed on the substrate. A base layer is disposed on the lateral conductivity layer and has the same electrical charge conductivity thereof. An emitter layer of a second doped electrical conductivity of opposite electrical charge is disposed on the base layer and forms a p-n junction therebetween. A plurality of spaced channels are formed in the emitter and base layers to expose the lateral conductivity layer at the bottoms thereof. A front contact grid is positioned on the top surface of the emitter layer of each cell. A first current collector is positioned along one outside edge of at least one first cell. A back contact grid is positioned in the channels at the top surface of the device for engagement with the lateral conductivity layer. A second current collector is positioned along at least one outside edge of at least one oppositely disposed second cell. Finally, an interdigitation mechanism is provided for serially connecting the front contact grid of one cell to the back contact grid of an adjacent cell at the top surface of the device. 15 figs.

Effects of benoxinate hydrochloride 0.4% on the morphological appearance of the cornea using confocal microscopy.

PubMed

Perez-Gomez, Inma; Hollingsworth, Jo; Efron, Nathan

2004-03-01

To investigate whether benoxinate hydrochloride 0.4% used to make confocal microscopy more comfortable alters the morphology of the cornea as viewed with the confocal microscope. Confocal microscopy was performed on both eyes of 10 subjects prior to instillation of either topical anaesthetic or non-preserved sterile saline, on two randomly ordered occasions. Images of all corneal layers were analysed quantitatively and qualitatively in a masked fashion. The images were similar in appearance in 5/10 subjects, there was greater clarity when anaesthetic was instilled in 4/10 subjects, and in the remaining subject there was greater clarity when saline was used. Anaesthetic had no influence on anterior keratocyte density (AKD), posterior keratocyte density (PKD) or endothelial cell density (ECD). Local anaesthetic does not affect corneal morphology as imaged using the confocal microscope. However, failure to use anaesthetic may lead to a degradation of image quality due to patient discomfort and excessive eye movements.

The evaluation of layered separators for nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Gahn, Randall F.

1991-01-01

The concept of using layered separators to achieve the required electrolyte retention and bubble pressure fo nickel-hydrogen cells was evaluated in a boilerplate cell test. Zircar cloth, polyethylene paper and polypropylene felt were combined with a layer of radiation-grafted polyethylene film to achieve the required properties. Three cells of each layered separator were built and tested by characterization cycling and by low earth orbit cycling for 5000 cycles at 80 percent DOD. Three cells containing asbestos separators were used as the reference.

Identification of the Centrifuged Lipoaspirate Fractions Suitable for Postgrafting Survival.

PubMed

Qiu, Lihong; Su, Yingjun; Zhang, Dongliang; Song, Yajuan; Liu, Bei; Yu, Zhou; Guo, Shuzhong; Yi, Chenggang

2016-01-01

The Coleman centrifugation procedure generates fractions with different adipocyte and progenitor cell densities. This study aimed to identify all fractions that are feasible for implantation. Human lipoaspirates were processed by Coleman centrifugation. The centrifugates were divided arbitrarily into upper, middle, and lower layers. Adipocyte viability, morphology, numbers of stromal vascular fraction cells, and adipose-derived mesenchymal stem cells of each layer were determined. The 12-week volume retention of subcutaneously implanted 0.3-ml lipoasperate of each layer was investigated in an athymic mice model. Most damaged adipocytes were located in the upper layers, whereas the intact adipocytes were distributed in the middle and lower layers. A gradient of stromal vascular fraction cell density was formed in the centrifugates. The implant volume retentions of samples from the upper, middle, and lower layers were 33.44 ± 5.9, 55.11 ± 4.4, and 71.2 ± 5.8 percent, respectively. Furthermore, the middle and lower layers contained significantly more adipose-derived stem cells than did the upper layer. The lower layer contains more viable adipocytes and stromal vascular fraction cells leading to the highest implant volume retention, whereas the most impaired cells are distributed in the upper layer, leading to the least volume retention. Although with a lower stromal vascular fraction content, the middle layer has a substantial number of intact adipocytes that are capable of retaining partial adipose tissue volume after implantation, suggesting that the middle layer may be an alternative fat source when large volumes of fat grafts are needed for transplantation.

Using a periclinal chimera to unravel layer-specific gene expression in plants

PubMed Central

Filippis, Ioannis; Lopez-Cobollo, Rosa; Abbott, James; Butcher, Sarah; Bishop, Gerard J

2013-01-01

Plant organs are made from multiple cell types, and defining the expression level of a gene in any one cell or group of cells from a complex mixture is difficult. Dicotyledonous plants normally have three distinct layers of cells, L1, L2 and L3. Layer L1 is the single layer of cells making up the epidermis, layer L2 the single cell sub-epidermal layer and layer L3 constitutes the rest of the internal cells. Here we show how it is possible to harvest an organ and characterise the level of layer-specific expression by using a periclinal chimera that has its L1 layer from Solanum pennellii and its L2 and L3 layers from Solanum lycopersicum. This is possible by measuring the level of the frequency of species-specific transcripts. RNA-seq analysis enabled the genome-wide assessment of whether a gene is expressed in the L1 or L2/L3 layers. From 13 277 genes that are expressed in both the chimera and the parental lines and with at least one polymorphism between the parental alleles, we identified 382 genes that are preferentially expressed in L1 in contrast to 1159 genes in L2/L3. Gene ontology analysis shows that many genes preferentially expressed in L1 are involved in cutin and wax biosynthesis, whereas numerous genes that are preferentially expressed in L2/L3 tissue are associated with chloroplastic processes. These data indicate the use of such chimeras and provide detailed information on the level of layer-specific expression of genes. PMID:23725542

Semiconductor nanocrystal-based phagokinetic tracking

DOEpatents

Alivisatos, A Paul; Larabell, Carolyn A; Parak, Wolfgang J; Le Gros, Mark; Boudreau, Rosanne

2014-11-18

Methods for determining metabolic properties of living cells through the uptake of semiconductor nanocrystals by cells. Generally the methods require a layer of neutral or hydrophilic semiconductor nanocrystals and a layer of cells seeded onto a culture surface and changes in the layer of semiconductor nanocrystals are detected. The observed changes made to the layer of semiconductor nanocrystals can be correlated to such metabolic properties as metastatic potential, cell motility or migration.

InP solar cell with window layer

NASA Technical Reports Server (NTRS)

Jain, Raj K. (Inventor); Landis, Geoffrey A. (Inventor)

1994-01-01

The invention features a thin light transmissive layer of the ternary semiconductor indium aluminum arsenide (InAlAs) as a front surface passivation or 'window' layer for p-on-n InP solar cells. The window layers of the invention effectively reduce front surface recombination of the object semiconductors thereby increasing the efficiency of the cells.

Photovoltaic Cell Having A P-Type Polycrystalline Layer With Large Crystals

DOEpatents

Albright, Scot P.; Chamberlin, Rhodes R.

1996-03-26

A photovoltaic cell has an n-type polycrystalline layer and a p-type polycrystalline layer adjoining the n-type polycrystalline layer to form a photovoltaic junction. The p-type polycrystalline layer comprises a substantially planar layer portion having relatively large crystals adjoining the n-type polycrystalline layer. The planar layer portion includes oxidized impurities which contribute to obtainment of p-type electrical properties in the planar layer portion.

Front contact solar cell with formed electrically conducting layers on the front side and backside

DOEpatents

Cousins, Peter John

2012-06-26

A bipolar solar cell includes a backside junction formed by a silicon substrate and a first doped layer of a first dopant type on the backside of the solar cell. A second doped layer of a second dopant type makes an electrical connection to the substrate from the front side of the solar cell. A first metal contact of a first electrical polarity electrically connects to the first doped layer on the backside of the solar cell, and a second metal contact of a second electrical polarity electrically connects to the second doped layer on the front side of the solar cell. An external electrical circuit may be electrically connected to the first and second metal contacts to be powered by the solar cell.

Postnatal Migration of Cerebellar Interneurons

PubMed Central

Galas, Ludovic; Bénard, Magalie; Lebon, Alexis; Komuro, Yutaro; Schapman, Damien; Vaudry, Hubert; Vaudry, David; Komuro, Hitoshi

2017-01-01

Due to its continuing development after birth, the cerebellum represents a unique model for studying the postnatal orchestration of interneuron migration. The combination of fluorescent labeling and ex/in vivo imaging revealed a cellular highway network within cerebellar cortical layers (the external granular layer, the molecular layer, the Purkinje cell layer, and the internal granular layer). During the first two postnatal weeks, saltatory movements, transient stop phases, cell-cell interaction/contact, and degradation of the extracellular matrix mark out the route of cerebellar interneurons, notably granule cells and basket/stellate cells, to their final location. In addition, cortical-layer specific regulatory factors such as neuropeptides (pituitary adenylate cyclase-activating polypeptide (PACAP), somatostatin) or proteins (tissue-type plasminogen activator (tPA), insulin growth factor-1 (IGF-1)) have been shown to inhibit or stimulate the migratory process of interneurons. These factors show further complexity because somatostatin, PACAP, or tPA have opposite or no effect on interneuron migration depending on which layer or cell type they act upon. External factors originating from environmental conditions (light stimuli, pollutants), nutrients or drug of abuse (alcohol) also alter normal cell migration, leading to cerebellar disorders. PMID:28587295

S-layer and cytoplasmic membrane - exceptions from the typical archaeal cell wall with a focus on double membranes.

PubMed

Klingl, Andreas

2014-01-01

The common idea of typical cell wall architecture in archaea consists of a pseudo-crystalline proteinaceous surface layer (S-layer), situated upon the cytoplasmic membrane. This is true for the majority of described archaea, hitherto. Within the crenarchaea, the S-layer often represents the only cell wall component, but there are various exceptions from this wall architecture. Beside (glycosylated) S-layers in (hyper)thermophilic cren- and euryarchaea as well as halophilic archaea, one can find a great variety of other cell wall structures like proteoglycan-like S-layers (Halobacteria), glutaminylglycan (Natronococci), methanochondroitin (Methanosarcina) or double layered cell walls with pseudomurein (Methanothermus and Methanopyrus). The presence of an outermost cellular membrane in the crenarchaeal species Ignicoccus hospitalis already gave indications for an outer membrane similar to Gram-negative bacteria. Although there is just limited data concerning their biochemistry and ultrastructure, recent studies on the euryarchaeal methanogen Methanomassiliicoccus luminyensis, cells of the ARMAN group, and the SM1 euryarchaeon delivered further examples for this exceptional cell envelope type consisting of two membranes.

Transport velocity transformation - A convenient method for performance analysis of multilayer solar cell structure

NASA Technical Reports Server (NTRS)

Wolf, M.

1981-01-01

It is noted that in the case of low-level injection, space-charge quasi-neutrality, and spatially constant material parameters (including an electrostatic field), the individual layer can be treated analytically and the basic solar cell performance parameters can be evaluated from three equations. The first equation represents the transformation of the transport velocity across the layer from the other layer boundary. The second establishes the light-generated current output from the layer interface, under the influence of the transport velocities and minority-carrier density at both layer boundaries and of bulk recombination. The third equation describes the flow of these carriers across other layers. The power of the approach is considered to lie in its facility for analysis of the solar cell's performance layer by layer, giving a clear picture of the individual layer's influence on cell efficiency.

Electrical isolation of component cells in monolithically interconnected modules

DOEpatents

Wanlass, Mark W.

2001-01-01

A monolithically interconnected photovoltaic module having cells which are electrically connected which comprises a substrate, a plurality of cells formed over the substrate, each cell including a primary absorber layer having a light receiving surface and a p-region, formed with a p-type dopant, and an n-region formed with an n-type dopant adjacent the p-region to form a single pn-junction, and a cell isolation diode layer having a p-region, formed with a p-type dopant, and an n-region formed with an n-type dopant adjacent the p-region to form a single pn-junction, the diode layer intervening the substrate and the absorber layer wherein the absorber and diode interfacial regions of a same conductivity type orientation, the diode layer having a reverse-breakdown voltage sufficient to prevent inter-cell shunting, and each cell electrically isolated from adjacent cells with a vertical trench trough the pn-junction of the diode layer, interconnects disposed in the trenches contacting the absorber regions of adjacent cells which are doped an opposite conductivity type, and electrical contacts.

Cellular and Pectin Dynamics during Abscission Zone Development and Ripe Fruit Abscission of the Monocot Oil Palm

PubMed Central

Roongsattham, Peerapat; Morcillo, Fabienne; Fooyontphanich, Kim; Jantasuriyarat, Chatchawan; Tragoonrung, Somvong; Amblard, Philippe; Collin, Myriam; Mouille, Gregory; Verdeil, Jean-Luc; Tranbarger, Timothy J.

2016-01-01

The oil palm (Elaeis guineensis Jacq.) fruit primary abscission zone (AZ) is a multi-cell layered boundary region between the pedicel (P) and mesocarp (M) tissues. To examine the cellular processes that occur during the development and function of the AZ cell layers, we employed multiple histological and immunohistochemical methods combined with confocal, electron and Fourier-transform infrared (FT-IR) microspectroscopy approaches. During early fruit development and differentiation of the AZ, the orientation of cell divisions in the AZ was periclinal compared with anticlinal divisions in the P and M. AZ cell wall width increased earlier during development suggesting cell wall assembly occurred more rapidly in the AZ than the adjacent P and M tissues. The developing fruit AZ contain numerous intra-AZ cell layer plasmodesmata (PD), but very few inter-AZ cell layer PD. In the AZ of ripening fruit, PD were less frequent, wider, and mainly intra-AZ cell layer localized. Furthermore, DAPI staining revealed nuclei are located adjacent to PD and are remarkably aligned within AZ layer cells, and remain aligned and intact after cell separation. The polarized accumulation of ribosomes, rough endoplasmic reticulum, mitochondria, and vesicles suggested active secretion at the tip of AZ cells occurred during development which may contribute to the striated cell wall patterns in the AZ cell layers. AZ cells accumulated intracellular pectin during development, which appear to be released and/or degraded during cell separation. The signal for the JIM5 epitope, that recognizes low methylesterified and un-methylesterified homogalacturonan (HG), increased in the AZ layer cell walls prior to separation and dramatically increased on the separated AZ cell surfaces. Finally, FT-IR microspectroscopy analysis indicated a decrease in methylesterified HG occurred in AZ cell walls during separation, which may partially explain an increase in the JIM5 epitope signal. The results obtained through a multi-imaging approach allow an integrated view of the dynamic developmental processes that occur in a multi-layered boundary AZ and provide evidence for distinct regulatory mechanisms that underlie oil palm fruit AZ development and function. PMID:27200017

Rapid Fabricating Technique for Multi-Layered Human Hepatic Cell Sheets by Forceful Contraction of the Fibroblast Monolayer

PubMed Central

Sakai, Yusuke; Koike, Makiko; Hasegawa, Hideko; Yamanouchi, Kosho; Soyama, Akihiko; Takatsuki, Mitsuhisa; Kuroki, Tamotsu; Ohashi, Kazuo; Okano, Teruo; Eguchi, Susumu

2013-01-01

Cell sheet engineering is attracting attention from investigators in various fields, from basic research scientists to clinicians focused on regenerative medicine. However, hepatocytes have a limited proliferation potential in vitro, and it generally takes a several days to form a sheet morphology and multi-layered sheets. We herein report our rapid and efficient technique for generating multi-layered human hepatic cell (HepaRG® cell) sheets using pre-cultured fibroblast monolayers derived from human skin (TIG-118 cells) as a feeder layer on a temperature-responsive culture dish. Multi-layered TIG-118/HepaRG cell sheets with a thick morphology were harvested on day 4 of culturing HepaRG cells by forceful contraction of the TIG-118 cells, and the resulting sheet could be easily handled. In addition, the human albumin and alpha 1-antitrypsin synthesis activities of TIG-118/HepaRG cells were approximately 1.2 and 1.3 times higher than those of HepaRG cells, respectively. Therefore, this technique is considered to be a promising modality for rapidly fabricating multi-layered human hepatocyte sheets from cells with limited proliferation potential, and the engineered cell sheet could be used for cell transplantation with highly specific functions. PMID:23923035

Internal retinal layer thickness and macular migration after internal limiting membrane peeling in macular hole surgery.

PubMed

Faria, Mun Y; Ferreira, Nuno P; Mano, Sofia; Cristóvao, Diana M; Sousa, David C; Monteiro-Grillo, Manuel E

2018-05-01

To provide a spectral-domain optical coherence tomography (SD-OCT)-based analysis of retinal layers thickness and nasal displacement of closed macular hole after internal limiting membrane peeling in macular hole surgery. In this nonrandomized prospective interventional study, 36 eyes of 32 patients were subjected to pars plana vitrectomy and 3.5 mm diameter internal limiting membrane (ILM) peeling for idiopathic macular hole (IMH). Nasal and temporal internal retinal layer thickness were assessed with SD-OCT. Each scan included optic disc border so that distance between optic disc border and fovea were measured. Thirty-six eyes had a successful surgery with macular hole closure. Total nasal retinal thickening (p<0.001) and total temporal retinal thinning (p<0.0001) were observed. Outer retinal layers increased thickness after surgery (nasal p<0.05 and temporal p<0.01). Middle part of inner retinal layers (mIRL) had nasal thickening (p<0.001) and temporal thinning (p<0.05). The mIRL was obtained by deducting ganglion cell layer (GCL) and retinal nerve fiber layer (RNFL) thickness from overall thickness of the inner retinal layer. Papillofoveal distance was shorter after ILM peeling in macular hole surgery (3,651 ± 323 μm preoperatively and 3,361 ± 279 μm at 6 months; p<0.0001). Internal limiting membrane peel is associated with important alteration in inner retinal layer architecture, with thickening of mIRL and shortening of papillofoveal distance. These factors may contribute to recovery of disrupted foveal photoreceptor and vision improvement after IMH closure.

A golgi study of the optic tectum of the tegu lizard, Tupinambis nigropunctatus.

PubMed

Butler, A B; Ebbesson, O E

1975-06-01

The dendritic patterns of cells in the optic tectum of the tegu lizard, Tupinambis nigropunctatus, were analyzed with the Ramon-Moliner modification of the Golgi-Cox technique. Cell types were compared with those described by other authors in the tectum of other reptiles; particular comparisons of our results were made with the description of cell types in the chameleon (Ramń, 1896), as the latter is the most complete analysis in the literature. The periventricular gray layers 3 and 5 consist primarily of two cell types--piriform or pyramidal shaped cells and horizontal cells. Cells in the medial portion of the tectum, in an area coextensive with the bilateral spinal projection zone, possess dendrites that extend across the midline. The latter cells have either fusiform or pyramidal shaped somas. The central white zone, layer 6, contains fibers, large fusiform or pyramidal shaped cells, fusiform cells, and small horizontal cells. The central gray zone, layer 7, is composed predominately of fusiform cells which have dendrites extending to the superficial optic layers, large polygonal cells, and horizontal cells. The superficial gray and white layers, layers 8-13, contain polygonal, fusiform, stellate, and horizontal elements. Layer 14 is composed solely of afferent optic tract fibers. Several differences in the occurrence and distribution of cell types between the tegu and the other reptiles studied are noted. Additionally, the laminar distribution of retinal, tectotectal, telencephalic, and spinal projections in the tegutectum can be related to the distribution of cell types, and those cells which may be postsynaptic to specific inputs can be identified. The highly differentiated laminar structure of the reptilian optic tectum, both in regard to cell type and to afferent and efferent connections, may serve as a model for studying some functional properties of lamination common to cortical structures.

The relationships between deformation mechanisms and mechanical properties of additively manufactured porous biomaterials.

PubMed

Kadkhodapour, J; Montazerian, H; Darabi, A Ch; Zargarian, A; Schmauder, S

2017-06-01

Modulating deformation mechanism through manipulating morphological parameters of scaffold internal pore architecture provides potential to tailor the overall mechanical properties under physiological loadings. Whereas cells sense local strains, cell differentiation is also impressed by the elastic deformations. In this paper, structure-property relations were developed for Ti6-Al-4V scaffolds designed based on triply periodic minimal surfaces. 10mm cubic scaffolds composed of 5×5×5 unit cells formed of F-RD (bending dominated) and I-WP (stretching dominated) architectures were additively manufactured at different volume fractions and subjected to compressive tests. The first stages of deformation for stretching dominated structure, was accompanied by bilateral layer-by-layer failure of unit cells owing to the buckling of micro-struts, while for bending dominated structure, namely F-RD, global shearing bands appeared since the shearing failure of struts in the internal architecture. Promoted mechanical properties were found for stretching dominated structure since the global orientation of struts were parallel to loading direction while inclination of struts diminished specific properties for bending dominated structure. Moreover, elastic-plastic deformation was computationally studied by applying Johnson-Cook damage model to the voxel-based models in FE analysis. Scaling analysis was performed for mechanical properties with respect to the relative density thereby failure mechanism was correlated to the constants of power law describing mechanical properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Unitized Regenerative Fuel Cell System Gas Storage-Radiator Development

NASA Technical Reports Server (NTRS)

Burke, Kenneth A.; Jakupta, Ian

2005-01-01

High-energy-density regenerative fuel cell systems that are used for energy storage require novel approaches to integrating components in order to preserve mass and volume. A lightweight unitized regenerative fuel cell (URFC) energy storage system concept is being developed at the NASA Glenn Research Center. This URFC system minimizes mass by using the surface area of the hydrogen and oxygen storage tanks as radiating heat surfaces for overall thermal control of the system. The waste heat generated by the URFC stack during charging and discharging is transferred from the cell stack to the surface of each tank by loop heat pipes, which are coiled around each tank and covered with a thin layer of thermally conductive carbon composite. The thin layer of carbon composite acts as a fin structure that spreads the heat away from the heat pipe and across the entire tank surface. Two different-sized commercial-grade composite tanks were constructed with integral heat pipes and tested in a thermal vacuum chamber to examine the feasibility of using the storage tanks as system radiators. The storage tank-radiators were subjected to different steady-state heat loads and varying heat load profiles. The surface emissivity and specific heat capacity of each tank were calculated. In the future, the results will be incorporated into a model that simulates the performance of similar radiators using lightweight, spacerated carbon composite tanks.

Use of yeast spores for microencapsulation of enzymes.

PubMed

Shi, Libing; Li, Zijie; Tachikawa, Hiroyuki; Gao, Xiao-Dong; Nakanishi, Hideki

2014-08-01

Here, we report a novel method to produce microencapsulated enzymes using Saccharomyces cerevisiae spores. In sporulating cells, soluble secreted proteins are transported to the spore wall. Previous work has shown that the spore wall is capable of retaining soluble proteins because its outer layers work as a diffusion barrier. Accordingly, a red fluorescent protein (RFP) fusion of the α-galactosidase, Mel1, expressed in spores was observed in the spore wall even after spores were subjected to a high-salt wash in the presence of detergent. In vegetative cells, however, the cell wall cannot retain the RFP fusion. Although the spore wall prevents diffusion of proteins, it is likely that smaller molecules, such as sugars, pass through it. In fact, spores can contain much higher α-galactosidase activity to digest melibiose than vegetative cells. When present in the spore wall, the enzyme acquires resistance to environmental stresses including enzymatic digestion and high temperatures. The outer layers of the spore wall are required to retain enzymes but also decrease accessibility of the substrates. However, mutants with mild spore wall defects can retain and stabilize the enzyme while still permitting access to the substrate. In addition to Mel1, we also show that spores can retain the invertase. Interestingly the encapsulated invertase has significantly lower activity toward raffinose than toward sucrose.This suggests that substrate selectivity could be altered by the encapsulation.

Impact of the deposition conditions of buffer and windows layers on lowering the metastability effects in Cu(In,Ga)Se2/Zn(S,O)-based solar cell

NASA Astrophysics Data System (ADS)

Naghavi, Negar; Hildebrandt, Thibaud; Bouttemy, Muriel; Etcheberry, Arnaud; Lincot, Daniel

2016-02-01

The highest and most reproducible (Cu(In,Ga)Se2 (CIGSe) based solar-cell efficiencies are obtained by use of a very thin n-type CdS layer deposited by chemical bath deposition (CBD). However because of both Cadmium's adverse environmental impact and the narrow bandgap of CdS (2.4-2.5 eV) one of the major objectives in the field of CIGSe technology remains the development and implementation in the production line of Cd-free buffer layers. The CBDZn( S,O) remains one the most studied buffer layer for replacing the CdS in Cu(In,Ga)Se2-based solar cells and has already demonstrated its potential to lead to high-efficiency solar cells up to 22.3%. However one of the key issue to implement a CBD-Zn(S,O) process in a CIGSe production line is the cells stability, which depends both on the deposition conditions of CBD-Zn(S,O) and on a good band alignment between CIGSe/Zn(S,O)/windows layers. The most common window layers applied in CIGSe solar cells consist of two layers : a thin (50-100 nm) and highly resistive i-ZnO layer deposited by magnetron sputtering and a transparent conducting 300-500 nm ZnO:Al layer. In the case of CBD-Zn(S,O) buffer layer, the nature and deposition conditions of both Zn(S,O) and the undoped window layer can strongly influence the performance and stability of cells. The present contribution will be specially focused on the effect of condition growth of CBD-Zn(S,O) buffer layers and the impact of the composition and deposition conditions of the undoped window layers such as ZnxMgyO or ZnxSnyO on the stability and performance of these solar cells.

A theoretical analysis of the current-voltage characteristics of solar cells. [and their energy conversion efficiency

NASA Technical Reports Server (NTRS)

Dunbar, P. M.; Hauser, J. R.

1976-01-01

Various mechanisms which limit the conversion efficiency of silicon solar cells were studied. The effects of changes in solar cell geometry such as layer thickness on performance were examined. The effects of various antireflecting layers were also examined. It was found that any single film antireflecting layer results in a significant surface loss of photons. The use of surface texturing techniques or low loss antireflecting layers can enhance by several percentage points the conversion efficiency of silicon cells. The basic differences between n(+)-p-p(+) and p(+)-n-n(+) cells are treated. A significant part of the study was devoted to the importance of surface region lifetime and heavy doping effects on efficiency. Heavy doping bandgap reduction effects are enhanced by low surface layer lifetimes, and conversely, the reduction in solar cell efficiency due to low surface layer lifetime is further enhanced by heavy doping effects. A series of computer studies is reported which seeks to determine the best cell structure and doping levels for maximum efficiency.

Electron-Selective TiO 2 Contact for Cu(In,Ga)Se 2 Solar Cells

DOE PAGES

Hsu, Weitse; Sutter-Fella, Carolin M.; Hettick, Mark; ...

2015-11-03

The non-toxic and wide bandgap material TiO 2 is explored as an n-type buffer layer on p-type Cu(In,Ga)Se 2 (CIGS) absorber layer for thin film solar cells. The amorphous TiO 2 thin film deposited by atomic layer deposition process at low temperatures shows conformal coverage on the CIGS absorber layer. Solar cells from non-vacuum deposited CIGS absorbers with TiO 2 buffer layer result in a high short-circuit current density of 38.9 mA/cm 2 as compared to 36.9 mA/cm 2 measured in the reference cell with CdS buffer layer, without compromising open-circuit voltage. The significant photocurrent gain, mainly in the UVmore » part of the spectrum, can be attributed to the low parasitic absorption loss in the ultrathin TiO 2 layer (~10 nm) with a larger bandgap of 3.4 eV compared to 2.4 eV of the traditionally used CdS. Overall the solar cell conversion efficiency was improved from 9.5% to 9.9% by substituting the CdS by TiO 2 on an active cell area of 10.5 mm2. In conclusion, optimized TiO 2/CIGS solar cells show excellent long-term stability. The results imply that TiO 2 is a promising buffer layer material for CIGS solar cells, avoiding the toxic CdS buffer layer with added performance advantage.« less

Optimization of Residual Stresses in MMC's through Process Parameter Control and the use of Heterogeneous Compensating/Compliant Interfacial Layers. OPTCOMP2 User's Guide

NASA Technical Reports Server (NTRS)

Pindera, Marek-Jerzy; Salzar, Robert S.

1996-01-01

A user's guide for the computer program OPTCOMP2 is presented in this report. This program provides a capability to optimize the fabrication or service-induced residual stresses in unidirectional metal matrix composites subjected to combined thermomechanical axisymmetric loading by altering the processing history, as well as through the microstructural design of interfacial fiber coatings. The user specifies the initial architecture of the composite and the load history, with the constituent materials being elastic, plastic, viscoplastic, or as defined by the 'user-defined' constitutive model, in addition to the objective function and constraints, through a user-friendly data input interface. The optimization procedure is based on an efficient solution methodology for the inelastic response of a fiber/interface layer(s)/matrix concentric cylinder model where the interface layers can be either homogeneous or heterogeneous. The response of heterogeneous layers is modeled using Aboudi's three-dimensional method of cells micromechanics model. The commercial optimization package DOT is used for the nonlinear optimization problem. The solution methodology for the arbitrarily layered cylinder is based on the local-global stiffness matrix formulation and Mendelson's iterative technique of successive elastic solutions developed for elastoplastic boundary-value problems. The optimization algorithm employed in DOT is based on the method of feasible directions.

A Hybrid Tandem Solar Cell Combining a Dye-Sensitized and a Polymer Solar Cell.

PubMed

Shao, Zhipeng; Chen, Shuanghong; Zhang, Xuhui; Zhu, Liangzheng; Ye, Jiajiu; Dai, Songyuan

2016-06-01

A hybrid tandem solar cell was assambled by connecting a dye sensitized solar cell and a polymer solar cell in series. A N719 sensitized TiO2 was used as photocathode in dye-sensitized subcell, and a MEH-PPV/PCBM composite was used as active layer in the polymer subcell. The polymer subcell fabricated on the counter electrode of the dye sensitized solar cell. A solution processed TiO(x) layer was used as electron collection layer of the polymer sub cell and the charge recombination layer. The effects of the TiO(x) interlayer and the spectral overlap between the two sub cells have been studied and optimized. The results shows that a proper thickness of the TiO(x) layer is needed for tandem solar cells. Thick TiO(x) will enhance the series resistance, but too thin TiO(x), layer will damage the hole blocking effect and its hydrophilic. The resulting optimized tandem solar cells exhibited a power conversion efficiency of 1.28% with a V(oc) of 0.95 V under simulated 100 mW cm(-2) AM 1.5 illumination.

Characterization of vibrissa germinative cells: transition of cell types.

PubMed

Osada, A; Kobayashi, K

2001-12-01

Germinative cells, small cell masses attached to the stalks of dermal papillae that are able to differentiate into the hair shaft and inner root sheath, form follicular bulb-like structures when co-cultured with dermal papilla cells. We studied the growth characteristics of germinative cells to determine the cell types in the vibrissa germinative tissue. Germinative tissues, attaching to dermal papillae, were cultured on 3T3 feeder layers. The cultured keratinocytes were harvested and transferred, equally and for two passages, onto lined dermal papilla cells (LDPC) and/or 3T3 feeder layers. The resulting germinative cells were classified into three types in the present experimental condition. Type 1 cells grow very well on either feeder layer, whereas Type 3 cells scarcely grow on either feeder layer. Type 2 cells are very conspicuous and are reversible. They grow well on 3T3 but growth is suppressed on LDPC feeder layers. The Type 2 cells that grow well on 3T3 feeder layers, however, are suppressed when transferred onto LDPC and the Type 2 cells that are suppressed on LDPC begin to grow again on 3T3. The transition of one cell type to another in vitro and the cell types that these germinative cell types correspond to in vivo is discussed. It was concluded that stem cells or their close progenitors reside in the germinative tissues of the vibrissa bulb except at late anagen-early catagen.

An inhomogeneous thermal block model of man for the electromagnetic environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatterjee, I.; Gandhi, O.P.

An inhomogeneous four layer block thermal model of a human body, composed of 476 electromagnetic-sensitive cubical cells has been developed to study the effects of electromagnetic radiation. Varying tissue properties defined by thermal conductivity, specific heat, blood flow rate and metabolic heat production are accounted for by equations. Peripheral cell temperature is weight-averaged for total cell volume and is thereby higher than actual skin temperature. During electromagnetic field exposure, additional factors considered are increased blood flow rate caused by vasodilation and sweat-induced heat loss. Hot spots have been located in the model and numerical results are presented. Subjected to planemore » wave iradiation, the model's sweating and insensible perspiration cease and all temperatures converge. Testing during electromagnetic hyperthemia shows all temperature body parts to increase approximately at the same rate.« less

Application of porous silicon in solar cell

NASA Astrophysics Data System (ADS)

Maniya, Nalin H.; Ashokan, Jibinlal; Srivastava, Divesh N.

2018-05-01

Silicon is widely used in solar cell applications with over 95% of all solar cells produced worldwide composed of silicon. Nanostructured thin porous silicon (PSi) layer acting as anti-reflecting coating is used in photovoltaic solar cells due to its advantages including simple and low cost fabrication, highly textured surfaces enabling lowering of reflectance, controllability of thickness and porosity of layer, and high surface area. PSi layers have previously been reported to reduce the reflection of light and replaced the conventional anti-reflective coating layers on solar cells. This can essentially improve the efficiency and decrease the cost of silicon solar cells. Here, we investigate the reflectance of different PSi layers formed by varying current density and etching time. PSi layers were formed by a combination of current density including 60 and 80 mA/cm2 and time for fabrication as 2, 4, 6, and 8 seconds. The fabricated PSi layers were characterized using reflectance spectroscopy and field emission scanning electron microscopy. Thickness and pore size of PSi layer were increased with increase in etching time and current density, respectively. The reflectance of PSi layers was decreased with increase in etching time until 6 seconds and increased again after 6 seconds, which was observed across both the current density. Reduction in reflectance indicates the increase of absorption of light by silicon due to the thin PSi layer. In comparison with the reflectance of silicon wafer, PSi layer fabricated at 80 mA/cm2 for 6 seconds gave the best result with reduction in reflectance up to 57%. Thus, the application of PSi layer as an effective anti-reflecting coating for the fabrication of solar cell has been demonstrated.

Using a periclinal chimera to unravel layer-specific gene expression in plants.

PubMed

Filippis, Ioannis; Lopez-Cobollo, Rosa; Abbott, James; Butcher, Sarah; Bishop, Gerard J

2013-09-01

Plant organs are made from multiple cell types, and defining the expression level of a gene in any one cell or group of cells from a complex mixture is difficult. Dicotyledonous plants normally have three distinct layers of cells, L1, L2 and L3. Layer L1 is the single layer of cells making up the epidermis, layer L2 the single cell sub-epidermal layer and layer L3 constitutes the rest of the internal cells. Here we show how it is possible to harvest an organ and characterise the level of layer-specific expression by using a periclinal chimera that has its L1 layer from Solanum pennellii and its L2 and L3 layers from Solanum lycopersicum. This is possible by measuring the level of the frequency of species-specific transcripts. RNA-seq analysis enabled the genome-wide assessment of whether a gene is expressed in the L1 or L2/L3 layers. From 13 277 genes that are expressed in both the chimera and the parental lines and with at least one polymorphism between the parental alleles, we identified 382 genes that are preferentially expressed in L1 in contrast to 1159 genes in L2/L3. Gene ontology analysis shows that many genes preferentially expressed in L1 are involved in cutin and wax biosynthesis, whereas numerous genes that are preferentially expressed in L2/L3 tissue are associated with chloroplastic processes. These data indicate the use of such chimeras and provide detailed information on the level of layer-specific expression of genes. © 2013 East Malling Research The Plant Journal © 2013 John Wiley & Sons Ltd.

Comparative transcriptional survey between laser-microdissected cells from laminar abscission zone and petiolar cortical tissue during ethylene-promoted abscission in citrus leaves

PubMed Central

Agustí, Javier; Merelo, Paz; Cercós, Manuel; Tadeo, Francisco R; Talón, Manuel

2009-01-01

Background Abscission is the cell separation process by which plants are able to shed organs. It has a great impact on the yield of most crop plants. At the same time, the process itself also constitutes an excellent model to study cell separation processes, since it occurs in concrete areas known as abscission zones (AZs) which are composed of a specific cell type. However, molecular approaches are generally hampered by the limited area and cell number constituting the AZ. Therefore, detailed studies at the resolution of cell type are of great relevance in order to accurately describe the process and to identify potential candidate genes for biotechnological applications. Results Efficient protocols for the isolation of specific citrus cell types, namely laminar abscission zone (LAZ) and petiolar cortical (Pet) cells based on laser capture microdissection (LCM) and for RNA microextraction and amplification have been developed. A comparative transcriptome analysis between LAZ and Pet from citrus leaf explants subjected to an in-vitro 24 h ethylene treatment was performed utilising microarray hybridization and analysis. Our analyses of gene functional classes differentially represented in ethylene-treated LAZ revealed an activation program dominated by the expression of genes associated with protein synthesis, protein fate, cell type differentiation, development and transcription. The extensive repertoire of genes associated with cell wall biosynthesis and metabolism strongly suggests that LAZ layers activate both catabolic and anabolic wall modification pathways during the abscission program. In addition, over-representation of particular members of different transcription factor families suggests important roles for these genes in the differentiation of the effective cell separation layer within the many layers contained in the citrus LAZ. Preferential expression of stress-related and defensive genes in Pet reveals that this tissue is likely to be reprogrammed to prevent pathogen attacks and general abiotic stresses after organ shedding. Conclusion The LCM-based data generated in this survey represent the most accurate description of the main biological processes and genes involved in organ abscission in citrus. This study provides novel molecular insight into ethylene-promoted leaf abscission and identifies new putative target genes for characterization and manipulation of organ abscission in citrus. PMID:19852773

Phosphatidylserine Outer Layer Translocation Is Implicated in IL-10 Secretion by Human Regulatory B Cells

PubMed Central

Hahne, Michael; Combe, Bernard; Morel, Jacques; Daien, Claire I.

2017-01-01

B cells can have a regulatory role, mainly mediated by interleukin 10 (IL-10). IL-10 producing B cells (B10 cells) cells remain to be better characterized. Annexin V binds phosphatidylserine (PS), which is externalized during apoptosis. Previous works suggested that B10 cells are apoptotic cells since they bind Annexin V. Others showed that Annexin V binding could also be expressed on viable B cells. We aimed to explore if PS exposure can be a marker of B10 cells and if PS exposure has a functional role on B cell IL-10 production in healthy subjects. We found that B10 cells were significantly more often Annexin V+ than IL-10 non-producing B cells. After CpG activation, Annexin V+ B cells differentiated more often into B10 cells than Annexin Vneg B cells. Cell death and early apoptosis were similar between Annexin V+ and Annexin Vneg B cells. PS blockage, using biotinylated AnV and glyburide, decreased B10 cell differentiation. This study showed that B10 cells have an increased PS exposure independently of any apoptotic state. B cells exposing PS differentiate more into B10 cells whereas PS blockage inhibits B10 cells generation. These results strongly suggest a link between PS exposure and B10 cells. PMID:28072868

Roles of endothelial A-type lamins in migration of T cells on and under endothelial layers

NASA Astrophysics Data System (ADS)

Song, Kwang Hoon; Lee, Jaehyun; Park, Hyoungjun; Kim, Hye Mi; Park, Jeehun; Kwon, Keon Woo; Doh, Junsang

2016-03-01

Stiff nuclei in cell-dense microenvironments may serve as distinct biomechanical cues for cell migration, but such a possibility has not been tested experimentally. As a first step addressing this question, we altered nuclear stiffness of endothelial cells (ECs) by reducing the expression of A-type lamins using siRNA, and investigated the migration of T cells on and under EC layers. While most T cells crawling on control EC layers avoided crossing over EC nuclei, a significantly higher fraction of T cells on EC layers with reduced expression of A-type lamins crossed over EC nuclei. This result suggests that stiff EC nuclei underlying T cells may serve as “duro-repulsive” cues to direct T cell migration toward less stiff EC cytoplasm. During subendothelial migration under EC layers with reduced expression of A-type lamins, T cells made prolonged contact and substantially deformed EC nuclei, resulting in reduced speed and directional persistence. This result suggests that EC nuclear stiffness promotes fast and directionally persistent subendothelial migration of T cells by allowing minimum interaction between T cells and EC nuclei.

Bond layer for a solid oxide fuel cell, and related processes and devices

DOEpatents

Wu, Jian; Striker, Todd-Michael; Renou, Stephane; Gaunt, Simon William

2017-03-21

An electrically-conductive layer of material having a composition comprising lanthanum and strontium is described. The material is characterized by a microstructure having bimodal porosity. Another concept in this disclosure relates to a solid oxide fuel cell attached to at least one cathode interconnect by a cathode bond layer. The bond layer includes a microstructure having bimodal porosity. A fuel cell stack which incorporates at least one of the cathode bond layers is also described herein, along with related processes for forming the cathode bond layer.

Assessing similarity to primary tissue and cortical layer identity in induced pluripotent stem cell-derived cortical neurons through single-cell transcriptomics

PubMed Central

Handel, Adam E.; Chintawar, Satyan; Lalic, Tatjana; Whiteley, Emma; Vowles, Jane; Giustacchini, Alice; Argoud, Karene; Sopp, Paul; Nakanishi, Mahito; Bowden, Rory; Cowley, Sally; Newey, Sarah; Akerman, Colin; Ponting, Chris P.; Cader, M. Zameel

2016-01-01

Induced pluripotent stem cell (iPSC)-derived cortical neurons potentially present a powerful new model to understand corticogenesis and neurological disease. Previous work has established that differentiation protocols can produce cortical neurons, but little has been done to characterize these at cellular resolution. In particular, it is unclear to what extent in vitro two-dimensional, relatively disordered culture conditions recapitulate the development of in vivo cortical layer identity. Single-cell multiplex reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) was used to interrogate the expression of genes previously implicated in cortical layer or phenotypic identity in individual cells. Totally, 93.6% of single cells derived from iPSCs expressed genes indicative of neuronal identity. High proportions of single neurons derived from iPSCs expressed glutamatergic receptors and synaptic genes. And, 68.4% of iPSC-derived neurons expressing at least one layer marker could be assigned to a laminar identity using canonical cortical layer marker genes. We compared single-cell RNA-seq of our iPSC-derived neurons to available single-cell RNA-seq data from human fetal and adult brain and found that iPSC-derived cortical neurons closely resembled primary fetal brain cells. Unexpectedly, a subpopulation of iPSC-derived neurons co-expressed canonical fetal deep and upper cortical layer markers. However, this appeared to be concordant with data from primary cells. Our results therefore provide reassurance that iPSC-derived cortical neurons are highly similar to primary cortical neurons at the level of single cells but suggest that current layer markers, although effective, may not be able to disambiguate cortical layer identity in all cells. PMID:26740550

Application of 3A molecular sieve layer in dye-sensitized solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Yuan; Wang, Jinzhong, E-mail: jinzhong-wang@hit.edu.cn, E-mail: qingjiang.yu@hit.edu.cn; Yu, Qingjiang, E-mail: jinzhong-wang@hit.edu.cn, E-mail: qingjiang.yu@hit.edu.cn

2014-08-25

3A molecular sieve layer was used as dehydration and electronic-insulation layer on the TiO{sub 2} electrode of dye-sensitized solar cells. This layer diminished the effect of water in electrolyte efficiently and enhanced the performance of cells. The conversion efficiency increased from 9.58% to 10.2%. The good moisture resistance of cells was attributed to the three-dimensional interconnecting structure of 3A molecular sieve with strong adsorption of water molecule. While the performance enhancement benefited from the suppression of the charge recombination of electronic-insulation layer and scattering effect of large particles.

Production of Exocytic Vesicular Antigens by Primary Liver Cell Cultures

DTIC Science & Technology

1990-05-08

cells should be plated over the basement membrane proteins, and for optimal results, a second layer of protein should be precipitated over the cells...culture as two layer (two gelatin coated nylon sheets stapled together) and single layer carriers seeded with cells (Table 2). From the performance results...summarized in table 2, it can be seen that double sheets of 2% gelatin: 6% glutaraldehyde (carrier II) made the best carriers. A double layer of

Quantifying effects of cyclic stretch on cell-collagen substrate adhesiveness of vascular endothelial cells.

PubMed

Omidvar, Ramin; Tafazzoli-Shadpour, Mohammad; Mahmoodi-Nobar, Farbod; Azadi, Shohreh; Khani, Mohammad-Mehdi

2018-05-01

Vascular endothelium is continuously subjected to mechanical stimulation in the form of shear forces due to blood flow as well as tensile forces as a consequence of blood pressure. Such stimuli influence endothelial behavior and regulate cell-tissue interaction for an optimized functionality. This study aimed to quantify influence of cyclic stretch on the adhesive property and stiffness of endothelial cells. The 10% cyclic stretch with frequency of 1 Hz was applied to a layer of endothelial cells cultured on a polydimethylsiloxane substrate. Cell-substrate adhesion of endothelial cells was examined by the novel approach of atomic force microscope-based single-cell force spectroscopy and cell stiffness was measured by atomic force microscopy. Furthermore, the adhesive molecular bonds were evaluated using modified Hertz contact theory. Our results show that overall adhesion of endothelial cells with substrate decreased after cyclic stretch while they became stiffer. Based on the experimental results and theoretical modeling, the decrease in the number of molecular bonds after cyclic stretch was quantified. In conclusion, in vitro cyclic stretch caused alterations in both adhesive capacity and elastic modulus of endothelial cells through mechanotransductive pathways as two major determinants of the function of these cells within the cardiovascular system.

Mechanical properties of growing melanocytic nevi and the progression to melanoma

NASA Astrophysics Data System (ADS)

Taloni, Alessandro; Alemi, Alexander; Ciusani, Emilio; Sethna, James P.; Zapperi, Stefano; La Porta, Caterina A. M.; National Research Council Of Italy Team; Lassp, Department Of Physics, Cornell University Team; Istituto Neurologico Carlo Besta Collaboration; Department Of Biosciences, University Of Milano Team

2015-03-01

Melanocytic nevi are benign proliferations that sometimes turn into malignant melanoma in a way that is still unclear from the biochemical and genetic point of view. Diagnostic and prognostic tools are then mostly based on dermoscopic examination and morphological analysis of histological tissues. To investigate the role of mechanics and geometry in the morpholgical dynamics of melanocytic nevi, we present a computational model for cell proliferation in a layered non-linear elastic tissue. Our simulations show that the morphology of the nevus is correlated to the initial location of the proliferating cell starting the growth process and to the mechanical properties of the tissue. We also demonstrate that melanocytes are subject to compressive stresses that fluctuate widely in the nevus and depend on the growth stage. Numerical simulations of cells in the epidermis releasing matrix metalloproteinases display an accelerated invasion of the dermis by destroying the basal membrane. Moreover, we show experimentally that osmotic stress and collagen inhibit growth in primary melanoma cells while the effect is much weaker in metastatic cells.

Ontogenesis of the collapsed layer during haustorium development in the root hemi-parasite Santalum album Linn.

PubMed

Yang, X; Zhang, X; Teixeira da Silva, J A; Liang, K; Deng, R; Ma, G

2014-01-01

The structure and development of collapsed layers of the haustorium were studied in Santalum album Linn. Through light and transmission electron microscopy, it was shown that the collapsed layers originated from starch-containing cells when the haustorium developed an internal gland, thickened gradually and ultimately developed into the mantle, which, combined with the sucker, buckled the host root. We report on the presence of inter-collapsed layers for the first time. These layers develop after penetration into the host and are located between the intrusive tissues and the vascular meristematic region, gradually linking the collapsed layers and remains around the sucker. The proliferation of cells in the meristematic region and the 'host tropism' of cortical layers contribute to pressure within the haustorium and result in development of the collapsed layers. Besides, starch-containing cells that turn into collapsed layers are vulnerable to pressure as they lack a large vacuole, have uneven cell wall thickness and a loose cell arrangement. We proposed that the functions of collapsed layers are to efficiently assure that cell inclusion and energy concentrate at the inner meristematic region and are recycled to affect penetration, reinforce the physical connection between the sandalwood haustorium and host root, and supply space for haustorial development. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Thin film solar cell including a spatially modulated intrinsic layer

DOEpatents

Guha, Subhendu; Yang, Chi-Chung; Ovshinsky, Stanford R.

1989-03-28

One or more thin film solar cells in which the intrinsic layer of substantially amorphous semiconductor alloy material thereof includes at least a first band gap portion and a narrower band gap portion. The band gap of the intrinsic layer is spatially graded through a portion of the bulk thickness, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces. The band gap of the intrinsic layer is always less than the band gap of the doped layers. The gradation of the intrinsic layer is effected such that the open circuit voltage and/or the fill factor of the one or plural solar cell structure is enhanced.

Monolithic in-based III-V compound semiconductor focal plane array cell with single stage CCD output

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Cunningham, Thomas J. (Inventor); Krabach, Timothy N. (Inventor); Staller, Craig O. (Inventor)

1994-01-01

A monolithic semiconductor imager includes an indium-based III-V compound semiconductor monolithic active layer of a first conductivity type, an array of plural focal plane cells on the active layer, each of the focal plane cells including a photogate over a top surface of the active layer, a readout circuit dedicated to the focal plane cell including plural transistors formed monolithically with the monolithic active layer and a single-stage charge coupled device formed monolithically with the active layer between the photogate and the readout circuit for transferring photo-generated charge accumulated beneath the photogate during an integration period to the readout circuit. The photogate includes thin epitaxial semiconductor layer of a second conductivity type overlying the active layer and an aperture electrode overlying a peripheral portion of the thin epitaxial semiconductor layer, the aperture electrode being connectable to a photogate bias voltage.

Optimization of intrinsic layer thickness, dopant layer thickness and concentration for a-SiC/a-SiGe multilayer solar cell efficiency performance using Silvaco software

NASA Astrophysics Data System (ADS)

Yuan, Wong Wei; Natashah Norizan, Mohd; Salwani Mohamad, Ili; Jamalullail, Nurnaeimah; Hidayah Saad, Nor

2017-11-01

Solar cell is expanding as green renewable alternative to conventional fossil fuel electricity generation, but compared to other land-used electrical generators, it is a comparative beginner. Many applications covered by solar cells starting from low power mobile devices, terrestrial, satellites and many more. To date, the highest efficiency solar cell is given by GaAs based multilayer solar cell. However, this material is very expensive in fabrication and material costs compared to silicon which is cheaper due to the abundance of supply. Thus, this research is devoted to develop multilayer solar cell by combining two different layers of P-I-N structures with silicon carbide and silicon germanium. This research focused on optimising the intrinsic layer thickness, p-doped layer thickness and concentration, n-doped layer thickness and concentration in achieving the highest efficiency. As a result, both single layer a-SiC and a-SiGe showed positive efficiency improvement with the record of 27.19% and 9.07% respectively via parametric optimization. The optimized parameters is then applied on both SiC and SiGe P-I-N layers and resulted the convincing efficiency of 33.80%.

A novel form of epithelial wound healing of the embryonic epidermis.

PubMed

Armstrong, Margaret T; Turlo, Kirsten; Elges, Chris J; Dayton, Sarah M; Lee, Janet; Armstrong, Peter B

2006-08-01

The embryonic epidermis of amniotes is a two-cell layer sheet with a periderm positioned superficial to the basal cell layer which, itself, attaches apically to the basal surface of the periderm and basally to the basal lamina. The presence of the periderm is essential to maintain the basal layer as a two-dimensional monolayer. Wounds to the epidermis that remove selectively just the periderm are healed by a stacking of the basal layer cells that constitute the wound bed. Basal cell stacking involves the desertion of the basal lamina by many of the cells so as to increase their contact area with other basal layer cells. This suggests that a preferential adhesion to the planar basal lamina is not important for the monolayered organization of the basal layer but, instead, association with inner surface of the planar periderm is the principal process that maintains the basal layer as a monolayer. The conversion of the basal layer from monolayer to multilayer during wound healing diminishes its planar area, resulting in movement of the wound borders toward the center of the wound. This is a novel scenario for wound healing.

Efficient dye-sensitized solar cells from mesoporous zinc oxide nanostructures sensitized by N719 dye

NASA Astrophysics Data System (ADS)

Kumara, G. R. A.; Deshapriya, U.; Ranasinghe, C. S. K.; Jayaweera, E. N.; Rajapakse, R. M. G.

2018-03-01

Dye-sensitized solar cells (DSCs) have attracted a great deal of attention due to their low-cost and high power conversion efficiencies. They usually utilize an interconnected nanoparticle layer of TiO2 as the electron transport medium. From the fundamental point of view, faster mobility of electrons in ZnO is expected to contribute to better performance in DSCs than TiO2, though the actual practical situation is quite the opposite. In this research, we addressed this problem by first applying a dense layer of ZnO on FTO followed by a mesoporous layer of interconnected ZnO nanoparticle layer, both were prepared by spray pyrolysis technique. The best cell shows a power conversion efficiency of 5.2% when the mesoporous layer thickness is 14 μm and the concentration of the N719 dye in dye coating solution is 0.3 mM, while a cell without a dense layer shows 4.2% under identical conditions. The surface concentration of dye adsorbed in the cell with a dense layer and that without a dense layer are 5.00 × 10‑7 and 3.34 × 10‑7 mol/cm2, respectively. The cell with the dense layer has an electron lifetime of 54.81 ms whereas that without the dense layer is 11.08 ms. As such, the presence of the dense layer improves DSC characteristics of ZnO-based DSCs.

Multilayered Organization of Jasmonate Signalling in the Regulation of Root Growth

PubMed Central

Gasperini, Debora; Chételat, Aurore; Acosta, Ivan F.; Goossens, Jonas; Pauwels, Laurens; Goossens, Alain; Dreos, René; Alfonso, Esteban; Farmer, Edward E.

2015-01-01

Physical damage can strongly affect plant growth, reducing the biomass of developing organs situated at a distance from wounds. These effects, previously studied in leaves, require the activation of jasmonate (JA) signalling. Using a novel assay involving repetitive cotyledon wounding in Arabidopsis seedlings, we uncovered a function of JA in suppressing cell division and elongation in roots. Regulatory JA signalling components were then manipulated to delineate their relative impacts on root growth. The new transcription factor mutant myc2-322B was isolated. In vitro transcription assays and whole-plant approaches revealed that myc2-322B is a dosage-dependent gain-of-function mutant that can amplify JA growth responses. Moreover, myc2-322B displayed extreme hypersensitivity to JA that totally suppressed root elongation. The mutation weakly reduced root growth in undamaged plants but, when the upstream negative regulator NINJA was genetically removed, myc2-322B powerfully repressed root growth through its effects on cell division and cell elongation. Furthermore, in a JA-deficient mutant background, ninja1 myc2-322B still repressed root elongation, indicating that it is possible to generate JA-responses in the absence of JA. We show that NINJA forms a broadly expressed regulatory layer that is required to inhibit JA signalling in the apex of roots grown under basal conditions. By contrast, MYC2, MYC3 and MYC4 displayed cell layer-specific localisations and MYC3 and MYC4 were expressed in mutually exclusive regions. In nature, growing roots are likely subjected to constant mechanical stress during soil penetration that could lead to JA production and subsequent detrimental effects on growth. Our data reveal how distinct negative regulatory layers, including both NINJA-dependent and -independent mechanisms, restrain JA responses to allow normal root growth. Mechanistic insights from this work underline the importance of mapping JA signalling components to specific cell types in order to understand and potentially engineer the growth reduction that follows physical damage. PMID:26070206

Theoretical analyses of Baroclinic flows

NASA Technical Reports Server (NTRS)

Antar, B.

1982-01-01

A stability analysis of a thin horizontal rotating fluid layer which is subjected to arbitrary horizontal and vertical temperature gradients is presented. The basic state is a nonlinear Hadley cell which contains both Ekman and thermal boundary layers; it is given in closed form. The stability analysis is based on the linearized Navier-Stokes equations, and zonally symmetric perturbations in the form of waves propagating in the meridional direction are considered. Numerical methods were used for the stability problem. It was found that the instability sets in when the Richardson number is close to unity and that the critical Richardson number is a non-monotonic function of the Prandtl number. Further, it was found that the critical Richardson number decreases with increasing Ekman number until a critical value of the Ekman number is reached beyond which the fluid is stable.

Wound Healing from Dermal Grafts Containing CD34+ Cells Is Comparable to Wound Healing with Split-Thickness Skin Micrografts.

PubMed

Nuutila, Kristo; Singh, Mansher; Kruse, Carla; Eriksson, Elof

2017-08-01

Epidermal stem cells present in the skin appendages of the dermis might be crucial in wound healing. In this study, the authors located these cells in the dermis and evaluated their contribution to full-thickness wound healing in a porcine model. Four sequentially deeper 0.35-mm-thick skin grafts were harvested from the same donor site going down to 1.4 mm in depth (layers 1 through 4). The layers were minced to 0.8 × 0.8 × 0.35-mm micrografts and transplanted (1:2) onto full-thickness porcine wounds. Healing was monitored up to 28 days and biopsy specimens were collected on days 6 and 10. Multiple wound healing parameters were used to assess the quality of healing. The authors' results showed that wounds transplanted with layer 2 (0.35 to 0.7 mm) and layer 3 (0.7 to 1.05 mm) micrografts demonstrated reepithelialization rates comparable to that of split-thickness skin graft (layer 1, 0.00 to 0.35 mm; split-thickness skin graft) at day 10. At day 28, dermal micrografts (layers 2 and 3) showed quality of healing comparable to that of split-thickness skin grafts (layer 1) in terms of wound contraction and scar elevation index. The amounts of epidermal stem cells [cluster of differentiation (CD) 34] and basal keratinocytes (KRT14) at each layer were quantified by immunohistochemistry. The analysis showed that layers 2 and 3 contained the most CD34 cells and layer 1 was the richest in KRT14 cells. The immunohistochemistry also indicated that, by day 6, CD34 cells had differentiated into KRT14 cells, which migrated from the grafts and contributed to the reepithelialization of the wound.

Characterization of Three Different Unusual S-Layer Proteins from Viridibacillus arvi JG-B58 That Exhibits Two Super-Imposed S-Layer Proteins

PubMed Central

Günther, Tobias J.; Raff, Johannes; Pollmann, Katrin

2016-01-01

Genomic analyses of Viridibacillus arvi JG-B58 that was previously isolated from heavy metal contaminated environment identified three different putative surface layer (S-layer) protein genes namely slp1, slp2, and slp3. All three genes are expressed during cultivation. At least two of the V. arvi JG-B58 S-layer proteins were visualized on the surface of living cells via atomic force microscopy (AFM). These S-layer proteins form a double layer with p4 symmetry. The S-layer proteins were isolated from the cells using two different methods. Purified S-layer proteins were recrystallized on SiO2 substrates in order to study the structure of the arrays and self-assembling properties. The primary structure of all examined S-layer proteins lack some features that are typical for Bacillus or Lysinibacillus S-layers. For example, they possess no SLH domains that are usually responsible for the anchoring of the proteins to the cell wall. Further, the pI values are relatively high ranging from 7.84 to 9.25 for the matured proteins. Such features are typical for S-layer proteins of Lactobacillus species although sequence comparisons indicate a close relationship to S-layer proteins of Lysinibacillus and Bacillus strains. In comparison to the numerous descriptions of S-layers, there are only a few studies reporting the concomitant existence of two different S-layer proteins on cell surfaces. Together with the genomic data, this is the first description of a novel type of S-layer proteins showing features of Lactobacillus as well as of Bacillus-type S-layer proteins and the first study of the cell envelope of Viridibacillus arvi. PMID:27285458

Transport equations in an enzymatic glucose fuel cell

NASA Astrophysics Data System (ADS)

Jariwala, Soham; Krishnamurthy, Balaji

2018-01-01

A mathematical model is developed to study the effects of convective flux and operating temperature on the performance of an enzymatic glucose fuel cell with a membrane. The model assumes isothermal operating conditions and constant feed rate of glucose. The glucose fuel cell domain is divided into five sections, with governing equations describing transport characteristics in each region, namely - anode diffusion layer, anode catalyst layer (enzyme layer), membrane, cathode catalyst layer and cathode diffusion layer. The mass transport is assumed to be one-dimensional and the governing equations are solved numerically. The effects flow rate of glucose feed on the performance of the fuel cell are studied as it contributes significantly to the convective flux. The effects of operating temperature on the performance of a glucose fuel cell are also modeled. The cell performances are compared using cell polarization curves, which were found compliant with experimental observations.

Application of atomic force microscopy to microbial surfaces: from reconstituted cell surface layers to living cells.

PubMed

Dufrêne, Y F

2001-02-01

The application of atomic force microscopy (AFM) to probe the ultrastructure and physical properties of microbial cell surfaces is reviewed. The unique capabilities of AFM can be summarized as follows: imaging surface topography with (sub)nanometer lateral resolution; examining biological specimens under physiological conditions; measuring local properties and interaction forces. AFM is being used increasingly for: (i) visualizing the surface ultrastructure of microbial cell surface layers, including bacterial S-layers, purple membranes, porin OmpF crystals and fungal rodlet layers; (ii) monitoring conformational changes of individual membrane proteins; (iii) examining the morphology of bacterial biofilms, (iv) revealing the nanoscale structure of living microbial cells, including fungi, yeasts and bacteria, (v) mapping interaction forces at microbial surfaces, such as van der Waals and electrostatic forces, solvation forces, and steric/bridging forces; and (vi) probing the local mechanical properties of cell surface layers and of single cells.

Carbon corrosion of proton exchange membrane fuel cell catalyst layers studied by scanning transmission X-ray microscopy

NASA Astrophysics Data System (ADS)

Hitchcock, Adam P.; Berejnov, Viatcheslav; Lee, Vincent; West, Marcia; Colbow, Vesna; Dutta, Monica; Wessel, Silvia

2014-11-01

Scanning Transmission X-ray Microscopy (STXM) at the C 1s, F 1s and S 2p edges has been used to investigate degradation of proton exchange membrane fuel cell (PEM-FC) membrane electrode assemblies (MEA) subjected to accelerated testing protocols. Quantitative chemical maps of the catalyst, carbon support and ionomer in the cathode layer are reported for beginning-of-test (BOT), and end-of-test (EOT) samples for two types of carbon support, low surface area carbon (LSAC) and medium surface area carbon (MSAC), that were exposed to accelerated stress testing with upper potentials (UPL) of 1.0, 1.2, and 1.3 V. The results are compared in order to characterize catalyst layer degradation in terms of the amounts and spatial distributions of these species. Pt agglomeration, Pt migration and corrosion of the carbon support are all visualized, and contribute to differing degrees in these samples. It is found that there is formation of a distinct Pt-in-membrane (PTIM) band for all EOT samples. The cathode thickness shrinks due to loss of the carbon support for all MSAC samples that were exposed to the different upper potentials, but only for the most aggressive testing protocol for the LSAC support. The amount of ionomer per unit volume significantly increases indicating it is being concentrated in the cathode as the carbon corrosion takes place. S 2p spectra and mapping of the cathode catalyst layer indicates there are still sulfonate groups present, even in the most damaged material.

Photovoltaic cell

DOEpatents

Gordon, Roy G.; Kurtz, Sarah

1984-11-27

In a photovoltaic cell structure containing a visibly transparent, electrically conductive first layer of metal oxide, and a light-absorbing semiconductive photovoltaic second layer, the improvement comprising a thin layer of transition metal nitride, carbide or boride interposed between said first and second layers.

The primate fovea: Structure, function and development.

PubMed

Bringmann, Andreas; Syrbe, Steffen; Görner, Katja; Kacza, Johannes; Francke, Mike; Wiedemann, Peter; Reichenbach, Andreas

2018-03-30

A fovea is a pitted invagination in the inner retinal tissue (fovea interna) that overlies an area of photoreceptors specialized for high acuity vision (fovea externa). Although the shape of the vertebrate fovea varies considerably among the species, there are two basic types. The retina of many predatory fish, reptilians, and birds possess one (or two) convexiclivate fovea(s), while the retina of higher primates contains a concaviclivate fovea. By refraction of the incoming light, the convexiclivate fovea may function as image enlarger, focus indicator, and movement detector. By centrifugal displacement of the inner retinal layers, which increases the transparency of the central foveal tissue (the foveola), the primate fovea interna improves the quality of the image received by the central photoreceptors. In this review, we summarize ‒ with the focus on Müller cells of the human and macaque fovea ‒ data regarding the structure of the primate fovea, discuss various aspects of the optical function of the fovea, and propose a model of foveal development. The "Müller cell cone" of the foveola comprises specialized Müller cells which do not support neuronal activity but may serve optical and structural functions. In addition to the "Müller cell cone", structural stabilization of the foveal morphology may be provided by the 'z-shaped' Müller cells of the fovea walls, via exerting tractional forces onto Henle fibers. The spatial distribution of glial fibrillary acidic protein may suggest that the foveola and the Henle fiber layer are subjects to mechanical stress. During development, the foveal pit is proposed to be formed by a vertical contraction of the centralmost Müller cells. After widening of the foveal pit likely mediated by retracting astrocytes, Henle fibers are formed by horizontal contraction of Müller cell processes in the outer plexiform layer and the centripetal displacement of photoreceptors. A better understanding of the molecular, cellular, and mechanical factors involved in the developmental morphogenesis and the structural stabilization of the fovea may help to explain the (patho-) genesis of foveal hypoplasia and macular holes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Growth and behavior of chondrocytes on nano engineered surfaces and construction of micropatterned co-culture platforms using layer-by-layer platforms using layer-by-layer assembly lift-off method

NASA Astrophysics Data System (ADS)

Shaik, Jameel

Several approaches such as self-assembled monolayers and layer-by-layer assembled multilayer films are being used as tools to study the interactions of cells with biomaterials in vitro. In this study, the layer-by-layer assembly approach was used to create monolayer, bilayer, trilayer, five, ten and twenty-bilayer beds of eleven different biomaterials. The various biomaterials used were poly(styrene-sulfonate), fibronectin, poly-L-lysine, poly-D-lysine, laminin, bovine serum albumin, chondroitin sulfate, poly(ethyleneimine), polyethylene glycol amine, collagen and poly(dimethyldiallyl-ammonium chloride) with unmodified tissue-culture polystyrene as standard control. Three different cell lines---primary bovine articular chondrocytes, and two secondary cell lines, human chondrosarcoma cells and canine chondrocytes were used in these studies. Chondrocyte morphology and attachment, viability, proliferation, and functionality were determined using bright field microscopy, the Live/Dead viability assay, MTT assay, and immunocytochemistry, respectively. Atomic force microscopy of the nanofilms indicated an increase in surface roughness with increasing number of layers. The most important observations from the studies on primary bovine articular chondrocytes were that these cells exhibited increasing viability and cell metabolic activity with increasing number of bilayers. The increase in viability was more pronounced than the increase in cell metabolic activity. Also, bovine chondrocytes on bilayers of poly(dimethyldiallyl-ammonium chloride, poly-L-lysine, poly(styrene-sulfonate), and bovine serum albumin were substantially bigger in size and well-attached when compared to the cells grown on monolayer and trilayers. Lactate dehydrogenase assay performed on chondrosarcoma cells grown on 5- and 10-bilayer multilayer beds indicated that the 10-bilayer beds had reduced cytotoxicity compared to the 5-bilayer beds. MTT assay performed on canine chondrocytes grown on 5-, 10-, and 20-bilayer nanofilm beds revealed increasing cell metabolic activity for BSA with increasing bilayers. Micropatterned multilayer beds having poly-L-lysine, poly-D-lysine, laminin poly(dimethyldiallyl-ammonium chloride) and poly(ethyleneimine) as the terminating layers were fabricated using the Layer-by-layer Lift-off (LbL-LO) method that combines photolithography and LbL self-assembly. Most importantly, micropatterned co-culture platforms consisting of anti-CD 44 rat monoclonal and anti-rat osteopontin (MPIIIB101) antibodies were constructed using the LbL-LO method for the first time. These co-culture platforms have several applications especially for studies of stem and progenitor cells. Co-culture platforms exhibiting spatiotempora-based differentiation can be built with LbL-LO for the differentiation of stem cells into the desired cell lineage.

Inverted bulk-heterojunction organic solar cells with the transfer-printed anodes and low-temperature-processed ultrathin buffer layers

NASA Astrophysics Data System (ADS)

Itoh, Eiji; Sakai, Shota; Fukuda, Katsutoshi

2018-03-01

We studied the effects of a hole buffer layer [molybdenum oxide (MoO3) and natural copper oxide layer] and a low-temperature-processed electron buffer layer on the performance of inverted bulk-heterojunction organic solar cells in a device consisting of indium-tin oxide (ITO)/poly(ethylene imine) (PEI)/titanium oxide nanosheet (TiO-NS)/poly(3-hexylthiopnehe) (P3HT):phenyl-C61-butyric acid methylester (PCBM)/oxide/anode (Ag or Cu). The insertion of ultrathin TiO-NS (˜1 nm) and oxide hole buffer layers improved the open circuit voltage V OC, fill factor, and rectification properties owing to the effective hole blocking and electron transport properties of ultrathin TiO-NS, and to the enhanced work function difference between TiO-NS and the oxide hole buffer layer. The insertion of the TiO-NS contributed to the reduction in the potential barrier at the ITO/PEI/TiO-NS/active layer interface for electrons, and the insertion of the oxide hole buffer layer contributed to the reduction in the potential barrier for holes. The marked increase in the capacitance under positive biasing in the capacitance-voltage characteristics revealed that the combination of TiO-NS and MoO3 buffer layers contributes to the selective transport of electrons and holes, and blocks counter carriers at the active layer/oxide interface. The natural oxide layer of the copper electrode also acts as a hole buffer layer owing to the increase in the work function of the Cu surface in the inverted cells. The performance of the cell with evaporated MoO3 and Cu layers that were transfer-printed to the active layer was almost comparable to that of the cell with MoO3 and Ag layers directly evaporated onto the active layer. We also demonstrated comparable device performance in the cell with all-printed MoO3 and low-temperature-processed silver nanoparticles as an anode.

Plasmonic layers based on Au-nanoparticle-doped TiO2 for optoelectronics: structural and optical properties.

PubMed

Pedrueza, E; Sancho-Parramon, J; Bosch, S; Valdés, J L; Martinez-Pastor, J P

2013-02-15

The anti-reflective effect of dielectric coatings used in silicon solar cells has traditionally been the subject of intensive studies and practical applications. In recent years the interest has permanently grown in plasmonic layers based on metal nanoparticles, which are shown to increase light trapping in the underlying silicon. In the present work we have combined these two concepts by means of in situ synthesis of Au nanoparticles in a dielectric matrix (TiO2), which is commonly used as an anti-reflective coating in silicon solar cells, and added the third element: a 10-20% porosity in the matrix. The porosity is formed by means of a controllable wet etching by low concentration HF. As a consequence, the experimentally measured reflectance of silicon coated by such a plasmonic layer decreases to practically zero in a broad wavelength region around the localized surface plasmon resonance. Furthermore, we demonstrate that extinction and reflectance spectra of silicon coated by the plasmonic films can be successfully accounted for by means of Fresnel formulae, in which a double refractive index of the metal-dielectric material is used. This double refractive index cannot be explained by effective medium theory (Maxwell-Garnett, for example) and appears when the contribution of Au nanoparticles located at the TiO2/Si interface is high enough to result in formation of interface surface plasmon modes.

Thin-Layer Fuel Cell for Teaching and Classroom Demonstrations

ERIC Educational Resources Information Center

Shirkhanzadeh, M.

2009-01-01

A thin-layer fuel cell is described that is simple and easy to set up and is particularly useful for teaching and classroom demonstrations. The cell is both an electrolyzer and a fuel cell and operates using a thin layer of electrolyte with a thickness of approximately 127 micrometers and a volume of approximately 40 microliters. As an…

Detection of melanoma cells suspended in mononuclear cells and blood plasma using photoacoustic generation

NASA Astrophysics Data System (ADS)

Spradling, Emily M.; Viator, John A.

2009-02-01

Melanoma is the deadliest form of skin cancer. Although the initial malignant cells are removed, it is impossible to determine whether or not the cancer has metastasized until a secondary tumor forms that is large enough to detect with conventional imaging. Photoacoustic detection of circulating melanoma cells in the bloodstream has shown promise for early detection of metastasis that may aid in treatment of this aggressive cancer. When blood is irradiated with energy from an Nd:YAG laser at 532 nm, photoacoustic signals are created and melanoma cells can be differentiated from the surrounding cells based on waveforms produced by an oscilloscope. Before this can be used as a diagnostic technique, however, we needed to investigate several parameters. Specifically, the current technique involves the in vitro separation of blood through centrifugation to isolate and test only the white blood cell layer. Using this method, we have detected a single cultured melanoma cell among a suspension of white blood cells. However, the process could be made simpler if the plasma layer were used for detection instead of the white blood cell layer. This layer is easier to obtain after blood separation, the optical difference between plasma and melanoma cells is more pronounced in this layer than in the white blood cell layer, and the possibility that any stray red blood cells could distort the results is eliminated. Using the photoacoustic apparatus, we detected no melanoma cells within the plasma of whole blood samples spiked with cultured melanoma cells.

Extending Human Hematopoietic Stem Cell Survival In Vitro with Adipocytes

PubMed Central

Glettig, Dean Liang

2013-01-01

Abstract Human hematopoietic stem cells (hHSCs) cannot be maintained in vitro for extended time periods because they rapidly differentiate or die. To extend in vitro culture time, researchers have made attempts to use human mesenchymal stem cells (hMSCs) to create feeder layers that mimic the stem cell niche. We have conducted an array of experiments including adipocytes in these feeder layers that inhibit hHSC differentiation and by that prolong stem cell survival in vitro. The amount of CD34+ cells was quantified using flow cytometry. In a first experiment, feeder layers of undifferentiated hMSCs were compared with feeder layers differentiated toward osteoblasts or adipocytes using minimal medium, showing the highest survival rate where adipocytes were included. The same conclusion was drawn in a second experiment in comparing hMSCs with adipogenic feeder cells, using a culture medium supplemented with a cocktail of hHSC growth factors. In a third experiment, it was shown that direct cell–cell contact is necessary for the supportive effect of the feeder layers. In a fourth and fifth experiment the amount of adipocytes in the feeder layers were varied, and in all experiments a higher amount of adipocytes in the feeder layers showed a less rapid decay of CD34+ cells at later time points. We therefore concluded that adipocytes assist in suppressing hHSC differentiation and aid in prolonging their survival in vitro. PMID:23741628

Numerical investigation of optimized CZTSSe based solar cell in Wx-Amps environment

NASA Astrophysics Data System (ADS)

Mohanty, Soumya Priyadarshini; Padhy, Srinibasa; Chowdhury, Joy; Sing, Udai P.

2018-05-01

The CZTSSe is the modified version of CZTS with selenium infusion. It shows maximum efficiency in the band gap from 1 to 1.4 eV. In our present work CZTSSe based solar cell is investigated using Wx-Amps tool. The Mo layer, absorber layer, CdS layer, i-ZnO [4]and Al-ZnO layers with their electrical, optical and material parameters are fitted in the tool. The vital parameters such as carrier density, thickness of the CZTSSe absorber layer, operating temperature, CdS buffer layer thickness and its carrier density on the cell interpretation are calculated. From[4] the simulation results it is apparent that the optimal absorber layer varies from 2.9 µm to 3.7 µm. The temperature variation has a strong influence on the efficiency of the cell. An optimal efficiency of 22% (With Jsc=33 mA/cm2, Voc=0.98 V, and fill factor= 68%) are attained. These results will give some insight for makeing higher efficiency CZTSSe based solar cell.

Generating Inviscid and Viscous Fluid Flow Simulations over a Surface Using a Quasi-simultaneous Technique

NASA Technical Reports Server (NTRS)

Sturdza, Peter (Inventor); Martins-Rivas, Herve (Inventor); Suzuki, Yoshifumi (Inventor)

2014-01-01

A fluid-flow simulation over a computer-generated surface is generated using a quasi-simultaneous technique. The simulation includes a fluid-flow mesh of inviscid and boundary-layer fluid cells. An initial fluid property for an inviscid fluid cell is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. An initial boundary-layer fluid property a boundary-layer fluid cell is determined using the initial fluid property and a viscous fluid simulation that simulates fluid viscous effects. An updated boundary-layer fluid property is determined for the boundary-layer fluid cell using the initial fluid property, initial boundary-layer fluid property, and an interaction law. The interaction law approximates the inviscid fluid simulation using a matrix of aerodynamic influence coefficients computed using a two-dimensional surface panel technique and a fluid-property vector. An updated fluid property is determined for the inviscid fluid cell using the updated boundary-layer fluid property.

A novel (ex situ) method to quantify oxygen diffusion coefficient of polymer fuel cells backing and catalyst layers

NASA Astrophysics Data System (ADS)

Baricci, Andrea; Casalegno, Andrea

2016-09-01

Limiting current density of oxygen reduction reaction in polymer electrolyte fuel cells is determined by several mass transport resistances that lower the concentration of oxygen on the catalyst active site. Among them, diffusion across porous media plays a significant role. Despite the extensive experimental activity documented in PEMFC literature, only few efforts have been dedicated to the measurement of the effective transport properties in porous layers. In the present work, a methodology for ex situ measurement of the effective diffusion coefficient and Knudsen radius of porous layers for polymer electrolyte fuel cells (gas diffusion layer, micro porous layer and catalyst layer) is described and applied to high temperature polymer fuel cells State of Art materials. Regression of the measured quantities by means of a quasi 2D physical model is performed to quantify the Knudsen effect, which is reported to account, respectively, for 30% and 50% of the mass transport resistance in micro porous layer and catalyst layer. On the other side, the model reveals that pressure gradient consequent to permeation in porous layers of high temperature polymer fuel cells has a negligible effect on oxygen concentration in relevant operating conditions.

Endothelial glycocalyx: permeability barrier and mechanosensor.

PubMed

Curry, F E; Adamson, R H

2012-04-01

Endothelial cells are covered with a polysaccharide rich layer more than 400 nm thick, mechanical properties of which limit access of circulating plasma components to endothelial cell membranes. The barrier properties of this endothelial surface layer are deduced from the rate of tracer penetration into the layer and the mechanics of red and white cell movement through capillary microvessels. This review compares the mechanosensor and permeability properties of an inner layer (100-150 nm, close to the endothelial membrane) characterized as a quasi-periodic structure which accounts for key aspects of transvascular exchange and vascular permeability with those of the whole endothelial surface layers. We conclude that many of the barrier properties of the whole surface layer are not representative of the primary fiber matrix forming the molecular filter determining transvascular exchange. The differences between the properties of the whole layer and the inner glycocalyx structures likely reflect dynamic aspects of the endothelial surface layer including tracer binding to specific components, synthesis and degradation of key components, activation of signaling pathways in the endothelial cells when components of the surface layer are lost or degraded, and the spatial distribution of adhesion proteins in microdomains of the endothelial cell membrane.

Effect of Lanthanum-Strontium Cathode Current-Collecting Layer on the Performance of Anode Supported Type Planar Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Park, Sun-Young; Ji, Ho-Il; Kim, Hae-Ryoung; Yoon, Kyung Joong; Son, Ji-Won; Lee, Hae-Weon; Lee, Jong-Ho

2013-07-01

We applied screen-printed (La,Sr)CoO3 as a current-collecting layer of planar type unit-cell for lower temperature operation of SOFCs. In this study the effects of the cathode current-collecting layer on the performance of unit cell and symmetric half cell were investigated via AC and DC polarization experiments. According to our investigation, appropriately controlled current collecting layer was very effective to enhance the unit cell performance by reducing not only the ohmic resistance but also the polarization losses of SOFC cathode.

Atomic-Layer-Deposited Transparent Electrodes for Silicon Heterojunction Solar Cells

DOE PAGES

Demaurex, Benedicte; Seif, Johannes P.; Smit, Sjoerd; ...

2014-11-01

We examine damage-free transparent-electrode deposition to fabricate high-efficiency amorphous silicon/crystalline silicon heterojunction solar cells. Such solar cells usually feature sputtered transparent electrodes, the deposition of which may damage the layers underneath. Using atomic layer deposition, we insert thin protective films between the amorphous silicon layers and sputtered contacts and investigate their effect on device operation. We find that a 20-nm-thick protective layer suffices to preserve, unchanged, the amorphous silicon layers beneath. Insertion of such protective atomic-layer-deposited layers yields slightly higher internal voltages at low carrier injection levels. However, we identify the presence of a silicon oxide layer, formed during processing,more » between the amorphous silicon and the atomic-layer-deposited transparent electrode that acts as a barrier, impeding hole and electron collection.« less

Cryopreservation of Human Stem Cells for Clinical Application: A Review

PubMed Central

Hunt, Charles J.

2011-01-01

Summary Stem cells have been used in a clinical setting for many years. Haematopoietic stem cells have been used for the treatment of both haematological and non-haematological disease; while more recently mesenchymal stem cells derived from bone marrow have been the subject of both laboratory and early clinical studies. Whilst these cells show both multipotency and expansion potential, they nonetheless do not form stable cell lines in culture which is likely to limit the breadth of their application in the field of regenerative medicine. Human embryonic stem cells are pluripotent cells, capable of forming stable cell lines which retain the capacity to differentiate into cells from all three germ layers. This makes them of special significance in both regenerative medicine and toxicology. Induced pluripotent stem (iPS) cells may also provide a similar breadth of utility without some of the confounding ethical issues surrounding embryonic stem cells. An essential pre-requisite to the commercial and clinical application of stem cells are suitable cryopreservation protocols for long-term storage. Whilst effective methods for cryopreservation and storage have been developed for haematopoietic and mesenchymal stem cells, embryonic cells and iPS cells have proved more refractory. This paper reviews the current state of cryopreservation as it pertains to stem cells and in particular the embryonic and iPS cell. PMID:21566712

Cryopreservation of Human Stem Cells for Clinical Application: A Review.

PubMed

Hunt, Charles J

2011-01-01

SUMMARY: Stem cells have been used in a clinical setting for many years. Haematopoietic stem cells have been used for the treatment of both haematological and non-haematological disease; while more recently mesenchymal stem cells derived from bone marrow have been the subject of both laboratory and early clinical studies. Whilst these cells show both multipotency and expansion potential, they nonetheless do not form stable cell lines in culture which is likely to limit the breadth of their application in the field of regenerative medicine. Human embryonic stem cells are pluripotent cells, capable of forming stable cell lines which retain the capacity to differentiate into cells from all three germ layers. This makes them of special significance in both regenerative medicine and toxicology. Induced pluripotent stem (iPS) cells may also provide a similar breadth of utility without some of the confounding ethical issues surrounding embryonic stem cells. An essential pre-requisite to the commercial and clinical application of stem cells are suitable cryopreservation protocols for long-term storage. Whilst effective methods for cryopreservation and storage have been developed for haematopoietic and mesenchymal stem cells, embryonic cells and iPS cells have proved more refractory. This paper reviews the current state of cryopreservation as it pertains to stem cells and in particular the embryonic and iPS cell.

Atomic layer deposition of ultrathin blocking layer for low-temperature solid oxide fuel cell on nanoporous substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Wonjong; Cho, Gu Young; Noh, Seungtak

2015-01-15

An ultrathin yttria-stabilized zirconia (YSZ) blocking layer deposited by atomic layer deposition (ALD) was utilized for improving the performance and reliability of low-temperature solid oxide fuel cells (SOFCs) supported by an anodic aluminum oxide substrate. Physical vapor-deposited YSZ and gadolinia-doped ceria (GDC) electrolyte layers were deposited by a sputtering method. The ultrathin ALD YSZ blocking layer was inserted between the YSZ and GDC sputtered layers. To investigate the effects of an inserted ultrathin ALD blocking layer, SOFCs with and without an ultrathin ALD blocking layer were electrochemically characterized. The open circuit voltage (1.14 V) of the ALD blocking-layered SOFC was visiblymore » higher than that (1.05 V) of the other cell. Furthermore, the ALD blocking layer augmented the power density and improved the reproducibility.« less

Composite Flood Risk for Virgin Island

EPA Pesticide Factsheets

The Composite Flood Risk layer combines flood hazard datasets from Federal Emergency Management Agency (FEMA) flood zones, NOAA's Shallow Coastal Flooding, and the National Hurricane Center SLOSH model for Storm Surge inundation for category 1, 2, and 3 hurricanes.Geographic areas are represented by a grid of 10 by 10 meter cells and each cell has a ranking based on variation in exposure to flooding hazards: Moderate, High and Extreme exposure. Geographic areas in each input layers are ranked based on their probability of flood risk exposure. The logic was such that areas exposed to flooding on a more frequent basis were given a higher ranking. Thus the ranking incorporates the probability of the area being flooded. For example, even though a Category 3 storm surge has higher flooding elevations, the likelihood of the occurrence is lower than a Category 1 storm surge and therefore the Category 3 flood area is given a lower exposure ranking. Extreme exposure areas are those areas that are exposed to relatively frequent flooding.The ranked input layers are then converted to a raster for the creation of the composite risk layer by using cell statistics in spatial analysis. The highest exposure ranking for a given cell in any of the three input layers is assigned to the corresponding cell in the composite layer.For example, if an area (a cell) is rank as medium in the FEMA layer, moderate in the SLOSH layer, but extreme in the SCF layer, the cell will be considere

Influence of the Preparation Method on Planar Perovskite CH3NH3PbI3-xClx Solar Cell Performance and Hysteresis

NASA Astrophysics Data System (ADS)

Ivanova, A.; Tokmakov, A.; Lebedeva, K.; Roze, M.; Kaulachs, I.

2017-08-01

Organometal halide perovskites are promising materials for lowcost, high-efficiency solar cells. The method of perovskite layer deposition and the interfacial layers play an important role in determining the efficiency of perovskite solar cells (PSCs). In the paper, we demonstrate inverted planar perovskite solar cells where perovskite layers are deposited by two-step modified interdiffusion and one-step methods. We also demonstrate how PSC parameters change by doping of charge transport layers (CTL). We used dimethylsupoxide (DMSO) as dopant for the hole transport layer (PEDOT:PSS) but for the electron transport layer [6,6]-phenyl C61 butyric acid methyl ester (PCBM)) we used N,N-dimethyl-N-octadecyl(3-aminopropyl)trimethoxysilyl chloride (DMOAP). The highest main PSC parameters (PCE, EQE, VOC) were obtained for cells prepared by the one-step method with fast crystallization and doped CTLs but higher fill factor (FF) and shunt resistance (Rsh) values were obtained for cells prepared by the two-step method with undoped CTLs.

Graphene Quantum Dot Layers with Energy-Down-Shift Effect on Crystalline-Silicon Solar Cells.

PubMed

Lee, Kyung D; Park, Myung J; Kim, Do-Yeon; Kim, Soo M; Kang, Byungjun; Kim, Seongtak; Kim, Hyunho; Lee, Hae-Seok; Kang, Yoonmook; Yoon, Sam S; Hong, Byung H; Kim, Donghwan

2015-09-02

Graphene quantum dot (GQD) layers were deposited as an energy-down-shift layer on crystalline-silicon solar cell surfaces by kinetic spraying of GQD suspensions. A supersonic air jet was used to accelerate the GQDs onto the surfaces. Here, we report the coating results on a silicon substrate and the GQDs' application as an energy-down-shift layer in crystalline-silicon solar cells, which enhanced the power conversion efficiency (PCE). GQD layers deposited at nozzle scan speeds of 40, 30, 20, and 10 mm/s were evaluated after they were used to fabricate crystalline-silicon solar cells; the results indicate that GQDs play an important role in increasing the optical absorptivity of the cells. The short-circuit current density was enhanced by about 2.94% (0.9 mA/cm(2)) at 30 mm/s. Compared to a reference device without a GQD energy-down-shift layer, the PCE of p-type silicon solar cells was improved by 2.7% (0.4 percentage points).

Inversion layer solar cell fabrication and evaluation. [measurement of response of inversion layer solar cell to light of different wavelengths

NASA Technical Reports Server (NTRS)

Call, R. L.

1973-01-01

Silicon solar cells operating with induced junctions rather than diffused junctions have been fabricated and tested. Induced junctions were created by forming an inversion layer near the surface of the silicon by supplying a sheet of positive charge above the surface. This charged layer was supplied through three mechanisms: (1) applying a positive potential to a transparent electrode separated from the silicon surface by a dielectric, (2) contaminating the oxide layer with positive ions, and (3) forming donor surface states that leave a positive charge on the surface. A movable semi-infinite shadow delineated the extent of sensitivity of the cell due to the inversion region. Measurements of the response of the inversion layer cell to light of different wavelengths indicated it to be more sensitive to the shorter wavelengths of the sun's spectrum than conventional cells. The greater sensitivity occurs because of the shallow junction and the strong electric field at the surface.

Solid oxide fuel cell operable over wide temperature range

DOEpatents

Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

2001-01-01

Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

Interfacial material for solid oxide fuel cell

DOEpatents

Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

1999-01-01

Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

Air stable organic-inorganic nanoparticles hybrid solar cells

DOEpatents

Qian, Lei; Yang, Jihua; Xue, Jiangeng; Holloway, Paul H.

2015-09-29

A solar cell includes a low work function cathode, an active layer of an organic-inorganic nanoparticle composite, a ZnO nanoparticle layer situated between and physically contacting the cathode and active layers; and a transparent high work function anode that is a bilayer electrode. The inclusion of the ZnO nanoparticle layer results in a solar cell displaying a conversion efficiency increase and reduces the device degradation rate. Embodiments of the invention are directed to novel ZnO nanoparticles that are advantageous for use as the ZnO nanoparticle layers of the novel solar cells and a method to prepare the ZnO nanoparticles.

TFB:TPDSi2 interfacial layer usable in organic photovoltaic cells

DOEpatents

Marks, Iobin J [Evanston, IL; Hains, Alexander W [Evanston, IL

2011-02-15

The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode; an active organic layer comprising an electron-donating organic material and an electron-accepting organic material; and an interfacial layer formed between the anode and active organic layer, where the interfacial layer comprises a hole-transporting polymer characterized with a hole-mobility higher than that of the electron-donating organic material in the active organic layer, and a small molecule that has a high hole-mobility and is capable of crosslinking on contact with air.

Cell Type-Specific Structural Organization of the Six Layers in Rat Barrel Cortex

PubMed Central

Narayanan, Rajeevan T.; Udvary, Daniel; Oberlaender, Marcel

2017-01-01

The cytoarchitectonic subdivision of the neocortex into six layers is often used to describe the organization of the cortical circuitry, sensory-evoked signal flow or cortical functions. However, each layer comprises neuronal cell types that have different genetic, functional and/or structural properties. Here, we reanalyze structural data from some of our recent work in the posterior-medial barrel-subfield of the vibrissal part of rat primary somatosensory cortex (vS1). We quantify the degree to which somata, dendrites and axons of the 10 major excitatory cell types of the cortex are distributed with respect to the cytoarchitectonic organization of vS1. We show that within each layer, somata of multiple cell types intermingle, but that each cell type displays dendrite and axon distributions that are aligned to specific cytoarchitectonic landmarks. The resultant quantification of the structural composition of each layer in terms of the cell type-specific number of somata, dendritic and axonal path lengths will aid future studies to bridge between layer- and cell type-specific analyses. PMID:29081739

InGaP Heterojunction Barrier Solar Cells

NASA Technical Reports Server (NTRS)

Welser, Roger E. (Inventor)

2014-01-01

A new solar cell structure called a heterojunction barrier solar cell is described. As with previously reported quantum-well and quantum-dot solar cell structures, a layer of narrow band-gap material, such as GaAs or indium-rich InGaP, is inserted into the depletion region of a wide band-gap PN junction. Rather than being thin, however, the layer of narrow band-gap material is about 400-430 nm wide and forms a single, ultrawide well in the depletion region. Thin (e.g., 20-50 nm), wide band-gap InGaP barrier layers in the depletion region reduce the diode dark current. Engineering the electric field and barrier profile of the absorber layer, barrier layer, and p-type layer of the PN junction maximizes photogenerated carrier escape. This new twist on nanostructured solar cell design allows the separate optimization of current and voltage to maximize conversion efficiency.

Passivating Window/First Layer AR Coating for Space Solar Cells

NASA Technical Reports Server (NTRS)

Faur, Mircea; Faur, Maria; Bailey, S. G.; Flood, D. J.; Brinker, D. J.; Alterovitz, S. A.; Wheeler, D. R.; Matesscu, G.; Goradia, C.; Goradia, M.

2004-01-01

Chemically grown oxides, if well designed, offer excellent surface passivation of the emitter surface of space solar cells and can be used as effective passivating window/first layer AR coating. In this paper, we demonstrate the effectiveness of using a simple room temperature wet chemical technique to grow cost effective passivating layers on solar cell front surfaces after the front grid metallization step. These passivating layers can be grown both on planar and porous surfaces. Our results show that these oxide layers: (i) can effectively passivate the from the surface, (ii) can serve as an effective optical window/first layer AR coating, (iii) are chemically, thermally and UV stable, and (iv) have the potential of improving the BOL and especially the EOL efficiency of space solar cells. The potential of using this concept to simplify the III-V based space cell heterostructures while increasing their BOL and EOL efficiency is also discussed.

Schottky barrier solar cell

NASA Technical Reports Server (NTRS)

Stirn, R. J.; Yeh, Y. C. M. (Inventor)

1981-01-01

A method of fabricating a Schottky barrier solar cell is described. The cell consists of a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive. A thin layer of heavily doped n-type polycrystalling germanium is deposited on the substrate after a passivation layer is deposited to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes to serve as a base layer on which a thin layer of gallium arsenide is vapor-epitaxilly grown followed by a thermally-grown oxide layer. A metal layer is deposited on the oxide layer and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer.

Hybrid shell engineering of animal cells for immune protections and regulation of drug delivery: towards the design of "artificial organs".

PubMed

Dandoy, Philippe; Meunier, Christophe F; Michiels, Carine; Su, Bao-Lian

2011-01-01

With the progress in medicine, the average human life expectancy is continuously increasing. At the same time, the number of patients who require full organ transplantations is augmenting. Consequently, new strategies for cell transplantation are the subject of great interest. This work reports the design, the synthesis and the characterisation of robust and biocompatible mineralised beads composed of two layers: an alginate-silica composite core and a Ca-alginate layer. The adequate choice of materials was achieved through cytotoxicity LDH release measurement and in vitro inflammatory assay (IL-8) to meet the biocompatibility requirements for medical purpose. The results obtained following this strategy provide a direct proof of the total innocuity of silica and alginate networks for human cells as underscored by the non-activation of immune defenders (THP-1 monocytes). The accessible pore size diameter of the mineralised beads synthesized was estimated between 22 and 30 nm, as required for efficient immuno-isolation without preventing the diffusion of nutrients and metabolites. The model human cells, HepG2, entrapped within these hybrid beads display a high survival rate over more than six weeks according to the measurements of intracellular enzymatic activity, respiration rate, as well as the "de novo" biosynthesis and secretion of albumin out of the beads. The current study shows that active mammalian cells can be protected by a silica-alginate hybrid shell-like system. The functionality of the cell strain can be maintained. Consequently, cells coated with an artificial and a biocompatible mineral shell could respond physiologically within the human body in order to deliver therapeutic agents in a controlled fashion (i.e. insulin), substituting the declining organ functions of the patient.

MicroRNA-205 targets tight junction-related proteins during urothelial cellular differentiation.

PubMed

Chung, Pei-Jung Katy; Chi, Lang-Ming; Chen, Chien-Lun; Liang, Chih-Lung; Lin, Chung-Tzu; Chang, Yu-Xun; Chen, Chun-Hsien; Chang, Yu-Sun

2014-09-01

The mammalian bladder urothelium classified as basal, intermediate, and terminally differentiated umbrella cells offers one of the most effective permeability barrier functions known to exist in nature because of the formation of apical uroplakin plaques and tight junctions. To improve our understanding of urothelial differentiation, we analyzed the microRNA (miRNA) expression profiles of mouse urinary tissues and by TaqMan miRNA analysis of microdissected urothelial layers and in situ miRNA-specific hybridization to determine the dependence of these miRNAs on the differentiation stage. Our in situ hybridization studies revealed that miR-205 was enriched in the undifferentiated basal and intermediate cell layers. We then used a quantitative proteomics approach to identify miR-205 target genes in primary cultured urothelial cells subjected to antagomir-mediated knockdown of specific miRNAs. Twenty-four genes were reproducibly regulated by miR-205; eleven of them were annotated as cell junction- and tight junction-related molecules. Western blot analysis demonstrated that antagomir-induced silencing of miR-205 in primary cultured urothelial cells elevated the expression levels of Tjp1, Cgnl1, and Cdc42. Ectopic expression of miR-205 in MDCK cells inhibited the expression of tight junction proteins and the formation of tight junctions. miR-205- knockdown urothelial cells showed alterations in keratin synthesis and increases of uroplakin Ia and Ib, which are the urothelial differentiation products. These results suggest that miR-205 may contribute a role in regulation of urothelial differentiation by modulating the expression of tight junction-related molecules. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Clinical Use of an Optical Coherence Tomography Linear Discriminant Function for Differentiating Glaucoma From Normal Eyes.

PubMed

Choi, Yun Jeong; Jeoung, Jin Wook; Park, Ki Ho; Kim, Dong Myung

2016-03-01

To determine and validate the diagnostic ability of a linear discriminant function (LDF) based on retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness obtained using high-definition optical coherence tomography (Cirrus HD-OCT) for discriminating between healthy controls and early glaucoma subjects. We prospectively selected 214 healthy controls and 152 glaucoma subjects (teaching set) and another independent sample of 86 healthy controls and 71 glaucoma subjects (validating set). Two scans, including 1 macular and 1 peripapillary RNFL scan, were obtained. After calculating the LDF in the teaching set using the binary logistic regression analysis, receiver operating characteristic curves were plotted and compared between the OCT-provided parameters and LDF in the validating set. The proposed LDF was 16.529-(0.132×superior RNFL)-(0.064×inferior RNFL)+(0.039×12 o'clock RNFL)+(0.038×1 o'clock RNFL)+(0.084×superior GCIPL)-(0.144×minimum GCIPL). The highest area under the receiver operating characteristic (AUROC) curve was obtained for LDF in both sets (AUROC=0.95 and 0.96). In the validating set, the LDF showed significantly higher AUROC than the best RNFL (inferior RNFL=0.91) and GCIPL parameter (minimum GCIPL=0.88). The LDF yielded a sensitivity of 93.0% at a fixed specificity of 85.0%. The LDF showed better diagnostic ability for differentiating between healthy and early glaucoma subjects than individual OCT parameters. A classification algorithm based on the LDF can be used in the OCT analysis for glaucoma diagnosis.

Epithelial-mesenchymal transition in colonies of rhesus monkey embryonic stem cells: a model for processes involved in gastrulation.

PubMed

Behr, Rüdiger; Heneweer, Carola; Viebahn, Christoph; Denker, Hans-Werner; Thie, Michael

2005-01-01

Rhesus monkey embryonic stem (rhES) cells were grown on mouse embryonic fibroblast (MEF) feeder layers for up to 10 days to form multilayered colonies. Within this period, stem cell colonies differentiated transiently into complex structures with a disc-like morphology. These complex colonies were characterized by morphology, immunohistochemistry, and marker mRNA expression to identify processes of epithelialization as well as epithelial-mesenchymal transition (EMT) and pattern formation. Typically, differentiated colonies were comprised of an upper and a lower ES cell layer, the former growing on top of the layer of MEF cells whereas the lower ES cell layer spread out underneath the MEF cells. Interestingly, in the central part of the colonies, a roundish pit developed. Here the feeder layer disappeared, and upper layer cells seemed to ingress and migrate through the pit downward to form the lower layer while undergoing a transition from the epithelial to the mesenchymal phenotype, which was indicated by the loss of the marker proteins E-cadherin and ZO-1 in the lower layer. In support of this, we found a concomitant 10-fold upregulation of the gene Snail2, which is a key regulator of the EMT process. Conversion of epiblast to mesoderm was also indicated by the regulated expression of the mesoderm marker Brachyury. An EMT is a characteristic process of vertebrate gastrulation. Thus, these rhES cell colonies may be an interesting model for studies on some basic processes involved in early primate embryogenesis and may open new ways to study the regulation of EMT in vitro.

New approaches for the analysis of confluent cell layers with quantitative phase digital holographic microscopy

NASA Astrophysics Data System (ADS)

Pohl, L.; Kaiser, M.; Ketelhut, S.; Pereira, S.; Goycoolea, F.; Kemper, Björn

2016-03-01

Digital holographic microscopy (DHM) enables high resolution non-destructive inspection of technical surfaces and minimally-invasive label-free live cell imaging. However, the analysis of confluent cell layers represents a challenge as quantitative DHM phase images in this case do not provide sufficient information for image segmentation, determination of the cellular dry mass or calculation of the cell thickness. We present novel strategies for the analysis of confluent cell layers with quantitative DHM phase contrast utilizing a histogram based-evaluation procedure. The applicability of our approach is illustrated by quantification of drug induced cell morphology changes and it is shown that the method is capable to quantify reliable global morphology changes of confluent cell layers.

Epidermal differentiation during ontogeny and after hatching in the snake Liasis fuscus (Pythonidae, Serpentes, Reptilia), with emphasis on the formation of the shedding complex.

PubMed

Alibardi, L; Thompson, M B

2003-04-01

Differentiation and localization of keratin in the epidermis during embryonic development and up to 3 months posthatching in the Australian water python, Liasis fuscus, was studied by ultrastructural and immunocytochemical methods. Scales arise from dome-like folds in the skin that produce tightly imbricating scales. The dermis of these scales is completely differentiated before any epidermal differentiation begins, with a loose dermis made of mesenchymal cells beneath the differentiating outer scale surface. At this stage (33) the embryo is still unpigmented and two layers of suprabasal cells contain abundant glycogen. At Stage 34 (beginning of pigmentation) the first layers of cells beneath the bilayered periderm (presumptive clear and oberhautchen layers) have not yet formed a shedding complex, within which prehatching shedding takes place. At Stage 35 the shedding complex, consisting of the clear and oberhautchen layers, is discernible. The clear layer contains a fine fibrous network that faces the underlying oberhautchen, where the spinulae initially contain a core of fibrous material and small beta-keratin packets. Differentiation continues at Stage 36 when the beta-layer forms and beta-keratin packets are deposited both on the fibrous core of the oberhautchen and within beta-cells. Mesos cells are produced from the germinal layer but remain undifferentiated. At Stage 37, before hatching, the beta-layer is compact, the mesos layer contains mesos granules, and cells of the alpha-layer are present but are not yet keratinized. They are still only partially differentiated a few hours after hatching, when a new shedding complex is forming underneath. Using antibodies against chick scale beta-keratin resolved at high magnification with immunofluorescent or immunogold conjugates, we offer the first molecular confirmation that in snakes only the oberhautchen component of the shedding complex and the underlying beta cells contain beta-keratin. Initially, there is little immunoreactivity in the small beta-packets of the oberhautchen, but it increases after fusion with the underlying cells to produce the syncytial beta layer. The beta-keratin packets coalesce with the tonofilaments, including those attached to desmosomes, which rapidly disappear in both oberhautchen and beta-cells as differentiation progresses. The labeling is low to absent in forming mesos-cells beneath the beta-layer. This study further supports the hypothesis that the shedding complex in lepidosaurian reptiles evolved after there was a segregation between alpha-keratogenic cells from beta-keratogenic cells during epidermal renewal. Copyright 2003 Wiley-Liss, Inc.

Encapsulant Material For Solar Cell Module And Laminated Glass Applications

DOEpatents

Hanoka, Jack I.

2000-09-05

An encapsulant material includes a layer of metallocene polyethylene disposed between two layers of ionomer. More specifically, the layer of metallocene polyethylene is disposed adjacent a rear surface of the first ionomer layer, and a second layer of ionomer is disposed adjacent a rear surface of the layer of metallocene polyethylene. The encapsulant material can be used in solar cell module and laminated glass applications.

The role of hydrogenated amorphous silicon oxide buffer layer on improving the performance of hydrogenated amorphous silicon germanium single-junction solar cells

NASA Astrophysics Data System (ADS)

Sritharathikhun, Jaran; Inthisang, Sorapong; Krajangsang, Taweewat; Krudtad, Patipan; Jaroensathainchok, Suttinan; Hongsingtong, Aswin; Limmanee, Amornrat; Sriprapha, Kobsak

2016-12-01

Hydrogenated amorphous silicon oxide (a-Si1-xOx:H) film was used as a buffer layer at the p-layer (μc-Si1-xOx:H)/i-layer (a-Si1-xGex:H) interface for a narrow band gap hydrogenated amorphous silicon germanium (a-Si1-xGex:H) single-junction solar cell. The a-Si1-xOx:H film was deposited by plasma enhanced chemical vapor deposition (PECVD) at 40 MHz in a same processing chamber as depositing the p-type layer. An optimization of the thickness of the a-Si1-xOx:H buffer layer and the CO2/SiH4 ratio was performed in the fabrication of the a-Si1-xGex:H single junction solar cells. By using the wide band gap a-Si1-xOx:H buffer layer with optimum thickness and CO2/SiH4 ratio, the solar cells showed an improvement in the open-circuit voltage (Voc), fill factor (FF), and short circuit current density (Jsc), compared with the solar cells fabricated using the conventional a-Si:H buffer layer. The experimental results indicated the excellent potential of the wide-gap a-Si1-xOx:H buffer layers for narrow band gap a-Si1-xGex:H single junction solar cells.

Proposed suitable electron reflector layer materials for thin-film CuIn1-xGaxSe2 solar cells

NASA Astrophysics Data System (ADS)

Sharbati, Samaneh; Gharibshahian, Iman; Orouji, Ali A.

2018-01-01

This paper investigates the electrical properties of electron reflector layer to survey materials as an electron reflector (ER) for chalcopyrite CuInGaSe solar cells. The purpose is optimizing the conduction-band and valence-band offsets at ER layer/CIGS junction that can effectively reduce the electron recombination near the back contact. In this work, an initial device model based on an experimental solar cell is established, then the properties of a solar cell with electron reflector layer are physically analyzed. The electron reflector layer numerically applied to baseline model of thin-film CIGS cell fabricated by ZSW (efficiency = 20.3%). The improvement of efficiency is achievable by electron reflector layer materials with Eg > 1.3 eV and -0.3 < Δχ < 0.7, depends on bandgap. Our simulations examine various electron reflector layer materials and conclude the most suitable electron reflector layer for this real CIGS solar cells. ZnSnP2, CdSiAs2, GaAs, CdTe, Cu2ZnSnS4, InP, CuO, Pb10Ag3Sb11S28, CuIn5S8, SnS, PbCuSbS3, Cu3AsS4 as well as CuIn1-xGaxSe (x > 0.5) are efficient electron reflector layer materials, so the potential improvement in efficiency obtained relative gain of 5%.

Method of making photovoltaic cell

DOEpatents

Cruz-Campa, Jose Luis; Zhou, Xiaowang; Zubia, David

2017-06-20

A photovoltaic solar cell comprises a nano-patterned substrate layer. A plurality of nano-windows are etched into an intermediate substrate layer to form the nano-patterned substrate layer. The nano-patterned substrate layer is positioned between an n-type semiconductor layer composed of an n-type semiconductor material and a p-type semiconductor layer composed of a p-type semiconductor material. Semiconductor material accumulates in the plurality of nano-windows, causing a plurality of heterojunctions to form between the n-type semiconductor layer and the p-type semiconductor layer.

Superstrate sub-cell voltage-matched multijunction solar cells

DOEpatents

Mascarenhas, Angelo; Alberi, Kirstin

2016-03-15

Voltage-matched thin film multijunction solar cell and methods of producing cells having upper CdTe pn junction layers formed on a transparent substrate which in the completed device is operatively positioned in a superstate configuration. The solar cell also includes a lower pn junction formed independently of the CdTe pn junction and an insulating layer between CdTe and lower pn junctions. The voltage-matched thin film multijunction solar cells further include a parallel connection between the CdTe pn junction and lower pn junctions to form a two-terminal photonic device. Methods of fabricating devices from independently produced upper CdTe junction layers and lower junction layers are also disclosed.

Composite fuel cell membranes

DOEpatents

Plowman, K.R.; Rehg, T.J.; Davis, L.W.; Carl, W.P.; Cisar, A.J.; Eastland, C.S.

1997-08-05

A bilayer or trilayer composite ion exchange membrane is described suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

Corrosion protected, multi-layer fuel cell interface

DOEpatents

Feigenbaum, Haim; Pudick, Sheldon; Wang, Chiu L.

1986-01-01

An improved interface configuration for use between adjacent elements of a fuel cell stack. The interface is impervious to gas and liquid and provides resistance to corrosion by the electrolyte of the fuel cell. The multi-layer configuration for the interface comprises a non-cupreous metal-coated metallic element to which is film-bonded a conductive layer by hot pressing a resin therebetween. The multi-layer arrangement provides bridging electrical contact.

Composite fuel cell membranes

DOEpatents

Plowman, Keith R.; Rehg, Timothy J.; Davis, Larry W.; Carl, William P.; Cisar, Alan J.; Eastland, Charles S.

1997-01-01

A bilayer or trilayer composite ion exchange membrane suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

Novel Solvent-free Perovskite Deposition in Fabrication of Normal and Inverted Architectures of Perovskite Solar Cells

PubMed Central

Nejand, Bahram Abdollahi; Gharibzadeh, Saba; Ahmadi, Vahid; Shahverdi, H. Reza

2016-01-01

We introduced a new approach to deposit perovskite layer with no need for dissolving perovskite precursors. Deposition of Solution-free perovskite (SFP) layer is a key method for deposition of perovskite layer on the hole or electron transport layers that are strongly sensitive to perovskite precursors. Using deposition of SFP layer in the perovskite solar cells would extend possibility of using many electron and hole transport materials in both normal and invert architectures of perovskite solar cells. In the present work, we synthesized crystalline perovskite powder followed by successful deposition on TiO2 and cuprous iodide as the non-sensitve and sensitive charge transport layers to PbI2 and CH3NH3I solution in DMF. The post compressing step enhanced the efficiency of the devices by increasing the interface area between perovskite and charge transport layers. The 9.07% and 7.71% cell efficiencies of the device prepared by SFP layer was achieved in respective normal (using TiO2 as a deposition substrate) and inverted structure (using CuI as deposition substrate) of perovskite solar cell. This method can be efficient in large-scale and low cost fabrication of new generation perovskite solar cells. PMID:27640991

Discrimination Between Patients With Alzheimer Disease and Healthy Subjects Using Layer Analysis of Cerebral Blood Flow and Xenon Solubility Coefficient in Xenon-Enhanced Computed Tomography.

PubMed

Sase, Shigeru; Yamamoto, Homaro; Kawashima, Ena; Tan, Xin; Sawa, Yutaka

The aim of this study was to develop a method for discriminating between patients with Alzheimer disease (AD) and healthy subjects using layer analysis of cerebral blood flow (CBF) and xenon solubility coefficient (λ) in xenon-enhanced computed tomography (CT). Xenon-enhanced CT was performed on 27 patients with AD (81.7 [3.3] years old) and 15 healthy volunteers (78.6 [4.0] years old) using a wide volume CT. For each subject, we created the first- (surface) to sixth-layer images of CBF and λ for the 6 viewing directions (layer thickness, 5 mm). For the discriminant views, receiver operating characteristic curves for the ratio of CBF to λ were created to identify patients with AD. For the third- and fourth-layer left lateral views, which were designated as the discriminant views, areas under the receiver operating characteristic curve were 96.8% and 97.4%, respectively. With the use of the discriminant views obtained by xenon-enhanced CT, we could effectively discriminate between patients with AD and healthy subjects using both CBF and λ.

Processing and Characterization of Thin Cadmium Telluride Solar Cells

NASA Astrophysics Data System (ADS)

Wojtowicz, Anna

Cadmium telluride (CdTe) has the highest theoretical limit to conversion efficiency of single-junction photovoltaic (PV) technologies today. However, despite a maximum theoretical open-circuit voltage of 1.20 V, record devices have historically had voltages pinned around only 900 mV. Voltage losses due to high recombination rates remains to be the most complex hurdle to CdTe technology today, and the subject of on-going research in the physics PV group at Colorado State University. In this work, an ultrathin CdTe device architecture is proposed in an effort to reduce bulk recombination and boost voltages. By thinning the CdTe layer, a device's internal electric field extends fully towards the back contact. This quickly separates electrons-hole pairs throughout the bulk of the device and reduces overall recombination. Despite this advantage, very thin CdTe layers also present a unique set of optical and electrical challenges which result in performance losses not as prevalent in thicker devices. When fabricating CdTe solar cells, post-deposition treatments applied to the absorber layer are a critical step for achieving high efficiency devices. Exposure of the polycrystalline CdTe film to a chlorine species encourages the passivation of dangling bonds and larger grain formation, while copper-doping improves device uniformity and voltages. This work focuses on experiments conducted via close-space sublimation to optimize CdCl2 and CuCl treatments for thin CdTe solar cells. Sweeps of both exposure and anneal time were performed for both post-deposition treatments on CdTe devices with 1.0 mum absorber layers. The results demonstrate that thin CdTe devices require substantially less post-deposition processing than standard thicker devices as expected. Additionally, the effects of CdTe growth temperature on thin devices is briefly investigated. The results suggest that higher growth temperatures lead to both electrical and stoichiometric changes in CdTe closely associated with lower carrier lifetimes and poorer overall performance.

Cell walls of the dimorphic fungal pathogens Sporothrix schenckii and Sporothrix brasiliensis exhibit bilaminate structures and sloughing of extensive and intact layers

PubMed Central

Walker, Louise A.; Niño-Vega, Gustavo; Mora-Montes, Héctor M.; Neves, Gabriela W. P.; Villalobos-Duno, Hector; Barreto, Laura; Garcia, Karina; Franco, Bernardo; Martínez-Álvarez, José A.; Munro, Carol A.; Gow, Neil A. R.

2018-01-01

Sporotrichosis is a subcutaneous mycosis caused by pathogenic species of the Sporothrix genus. A new emerging species, Sporothrix brasiliensis, is related to cat-transmitted sporotrichosis and has severe clinical manifestations. The cell wall of pathogenic fungi is a unique structure and impacts directly on the host immune response. We reveal and compare the cell wall structures of Sporothrix schenckii and S. brasiliensis using high-pressure freezing electron microscopy to study the cell wall organization of both species. To analyze the components of the cell wall, we also used infrared and 13C and 1H NMR spectroscopy and the sugar composition was determined by quantitative high-performance anion-exchange chromatography. Our ultrastructural data revealed a bi-layered cell wall structure for both species, including an external microfibrillar layer and an inner electron-dense layer. The inner and outer layers of the S. brasiliensis cell wall were thicker than those of S. schenckii, correlating with an increase in the chitin and rhamnose contents. Moreover, the outer microfibrillar layer of the S. brasiliensis cell wall had longer microfibrils interconnecting yeast cells. Distinct from those of other dimorphic fungi, the cell wall of Sporothrix spp. lacked α-glucan component. Interestingly, glycogen α-particles were identified in the cytoplasm close to the cell wall and the plasma membrane. The cell wall structure as well as the presence of glycogen α-particles varied over time during cell culture. The structural differences observed in the cell wall of these Sporothrix species seemed to impact its uptake by monocyte-derived human macrophages. The data presented here show a unique cell wall structure of S. brasiliensis and S. schenckii during the yeast parasitic phase. A new cell wall model for Sporothrix spp. is therefore proposed that suggests that these fungi molt sheets of intact cell wall layers. This observation may have significant effects on localized and disseminated immunopathology. PMID:29522522

Assessment of burned coal shale properties based on cyclic load

NASA Astrophysics Data System (ADS)

Grygierek, Marcin; Kalisz, Piotr; Pacześniowski, Krzysztof; Pytlik, Andrzej; Zięba, Magdalena

2018-04-01

Road surfaces that are subjected to cyclic loads generated by vehicle wheels must meet the requirements concerning the durability in the assumed period of use. The durability of the layered pavement construction systems depends on the value and frequency of the load as well as on the mechanical features of its individual layers. Layers of unbound, mechanically stabilized mixtures are a significant aspect of surfaces that are susceptible. Mixtures of this type can be applied both to the subgrade layers as well as to the bottom pavement layers, including the improved course. Considering the cyclic nature of the load on the surface of the entire system, mechanically stabilized layers are subject to continuous, but slow, densification during the period of use, which results in the formation of permanent deformations and so-called structural ruts. Post-mining waste is frequently used in road construction. which is the so-called burned shale that can be used for the bottom layers of the surface and layers of the improved subgrade (soil replacement). This material was the subject of the analysis. The evaluation was based mainly on the results of pilot studies covering cyclic loads of the layer/course made of the so-called red shale. The applied research method was aimed at preliminary assessment of its suitability for the assessment of the behaviour of the disintegrated medium under the conditions of test loads simulating the movement of vehicles.

Layer-by-layer-based silica encapsulation of individual yeast with thickness control.

PubMed

Lee, Hojae; Hong, Daewha; Choi, Ji Yu; Kim, Ji Yup; Lee, Sang Hee; Kim, Ho Min; Yang, Sung Ho; Choi, Insung S

2015-01-01

In the area of cell-surface engineering with nanomaterials, the metabolic and functional activities of the encapsulated cells are manipulated and controlled by various parameters of the artificial shells that encase the cells, such as stiffness and elasticity, thickness, and porosity. The mechanical durability and physicochemical stability of inorganic shells prove superior to layer-by-layer-based organic shells with regard to cytoprotection, but it has been difficult to vary the parameters of inorganic shells including their thickness. In this work, we combine the layer-by-layer technique with a process of bioinspired silicification to control the thickness of the silica shells that encapsulate yeast Saccharomyces cerevisiae cells individually, and investigate the thickness-dependent microbial growth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The layer boundary effect on multi-layer mesoporous TiO 2 film based dye sensitized solar cells

DOE PAGES

Xu, Feng; Zhu, Kai; Zhao, Yixin

2016-10-10

Multi-layer mesoporous TiO 2 prepared by screen printing is widely used for fabrication of high-efficiency dye-sensitized solar cells (DSSCs). Here, we compare the three types of ~10 um thick mesoporous TiO 2 films, which were screen printed as 1-, 2- and 4-layers using the same TiO 2 nanocrystal paste. The layer boundary of the multi-layer mesoporous TiO 2 films was observed in the cross-section SEM. The existence of a layer boundary could reduce the photoelectron diffusion length with the increase of layer number. However, the photoelectron diffusion lengths of the Z907 dye sensitized solar cells based on these different layeredmore » mesoporous TiO 2 films are all longer than the film thickness. Consequently, the photovoltaic performance seems to have little dependence on the layer number of the multi-layer TiO 2 based DSSCs.« less

The layer boundary effect on multi-layer mesoporous TiO 2 film based dye sensitized solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Feng; Zhu, Kai; Zhao, Yixin

Multi-layer mesoporous TiO 2 prepared by screen printing is widely used for fabrication of high-efficiency dye-sensitized solar cells (DSSCs). Here, we compare the three types of ~10 um thick mesoporous TiO 2 films, which were screen printed as 1-, 2- and 4-layers using the same TiO 2 nanocrystal paste. The layer boundary of the multi-layer mesoporous TiO 2 films was observed in the cross-section SEM. The existence of a layer boundary could reduce the photoelectron diffusion length with the increase of layer number. However, the photoelectron diffusion lengths of the Z907 dye sensitized solar cells based on these different layeredmore » mesoporous TiO 2 films are all longer than the film thickness. Consequently, the photovoltaic performance seems to have little dependence on the layer number of the multi-layer TiO 2 based DSSCs.« less

Graphene interfaced perovskite solar cells: Role of graphene flake size

NASA Astrophysics Data System (ADS)

Sakorikar, Tushar; Kavitha, M. K.; Tong, Shi Wun; Vayalamkuzhi, Pramitha; Loh, Kian Ping; Jaiswal, Manu

2018-04-01

Graphene interfaced inverted planar heterojunction perovskite solar cells are fabricated by facile solution method and studied its potential as hole conducting layer. Reduced graphene oxide (rGO) with small and large flake size and Polyethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS) are utilized as hole conducting layers in different devices. For the solar cell employing PEDOT:PSS as hole conducting layer, 3.8 % photoconversion efficiency is achieved. In case of solar cells fabricated with rGO as hole conducting layer, the efficiency of the device is strongly dependent on flake size. With all other fabrication conditions kept constant, the efficiency of graphene-interfaced solar cell improves by a factor of 6, by changing the flake size of graphene oxide. We attribute this effect to uniform coverage of graphene layer and improved electrical percolation network.

Improved efficiency of NiOx-based p-i-n perovskite solar cells by using PTEG-1 as electron transport layer

NASA Astrophysics Data System (ADS)

Groeneveld, Bart G. H. M.; Najafi, Mehrdad; Steensma, Bauke; Adjokatse, Sampson; Fang, Hong-Hua; Jahani, Fatemeh; Qiu, Li; ten Brink, Gert H.; Hummelen, Jan C.; Loi, Maria Antonietta

2017-07-01

We present efficient p-i-n type perovskite solar cells using NiOx as the hole transport layer and a fulleropyrrolidine with a triethylene glycol monoethyl ether side chain (PTEG-1) as electron transport layer. This electron transport layer leads to higher power conversion efficiencies compared to perovskite solar cells with PCBM (phenyl-C61-butyric acid methyl ester). The improved performance of PTEG-1 devices is attributed to the reduced trap-assisted recombination and improved charge extraction in these solar cells, as determined by light intensity dependence and photoluminescence measurements. Through optimization of the hole and electron transport layers, the power conversion efficiency of the NiOx/perovskite/PTEG-1 solar cells was increased up to 16.1%.

Changes of myoid and endothelial cells in the peritubular wall during contraction of the seminiferous tubule.

PubMed

Losinno, Antonella D; Sorrivas, Viviana; Ezquer, Marcelo; Ezquer, Fernando; López, Luis A; Morales, Alfonsina

2016-08-01

The wall of the seminiferous tubule in rodents consists of an inner layer of myoid cells covered by an outer layer of endothelial cells. Myoid cells are a type of smooth muscle cell containing α-actin filaments arranged in two independent layers that contract when stimulated by endothelin-1. The irregular surface relief of the tubular wall is often considered a hallmark of contraction induced by a variety of stimuli. We examine morphological changes of the rat seminiferous tubule wall during contraction by a combination of light, confocal, transmission and scanning electron microscopy. During ET-1-induced contraction, myoid cells changed from a flat to a conical shape, but their actin filaments remained in independent layers. As a consequence of myoid cell contraction, the basement membrane became wavy, orientation of collagen fibers in the extracellular matrix was altered and the endothelial cell layer became folded. To observe the basement of the myoid cell cone, the endothelial cell monolayer was removed by collagenase digestion prior to SEM study. In contracted tubules, it is possible to distinguish cell relief: myoid cells have large folds on the external surface oriented parallel to the tubular axis, whereas endothelial cells have numerous cytoplasmic projections facing the interstitium. The myoid cell cytoskeleton is unusual in that the actin filaments are arranged in two orthogonal layers, which adopt differing shapes during contraction with myoid cells becoming cone-shaped. This arrangement impacts on other components of the seminiferous tubule wall and affects the propulsion of the tubular contents to the rete testis.

Composition of low-strength solder joints in solar-concentrator-cell arrays

NASA Astrophysics Data System (ADS)

Chamberlain, M. B.; Nordstrom, T. V.

Bond strengths of Cu strips soldered to the backside metallization of solar concentrator cells were found to be unacceptably low. To determine whether contaminants in the cell metallization caused these low strengths, unsoldered cells and soldered cells were characterized by scanning Auger microscopy. The backside metallization consisted of a 5 micrometers Ag conductor layer, a 150 nm Pd diffusion barrier and a 150 nm Ti adhesion layer next to an Al ohmic contact layer on the Si cell. The analysis showed that the Ti layer are partially oxidized during soldering, that Pb from the Pb-5 wt % Sn - 2.5 wt % Ag solder segregated during soldering to the Pd-oxidized Ti interface, and that low strength fractures occurred in this Pb layer at the Pd-oxidized Ti interface. The problem was solved by changing the ambient gas used during soldering from N2 to forming gas (80% N2 + 20% H2).

LM and TEM study of the orthokeratinized and parakeratinized epithelium of the tongue in the domestic duck (Anas platyrhynchos f. domestica).

PubMed

Skieresz-Szewczyk, Kinga; Jackowiak, Hanna; Ratajczak, Marlena

2014-12-01

The previous histological studies of the lingual mucosa in birds characterized two types of keratinized epithelium, i.e. orthokeratinized and parakeratinized. These epithelia are composed of three layers: basal, intermediate and keratinized. The present study showed detailed ultrastructural features of cells in particular layers of two types of keratinized epithelia on the tongue in the domestic duck and defined structural differences. TEM observations showed a gradual reduction in cell organelles in the following layers, at increasing amounts of keratin fibers. The characteristic feature of the ortho- and parakeratinized epithelium is the presence of sub-layers in the intermediate layer, i.e. the upper and lower part, which results from the different shape of cell nuclei and dye affinity of the cytoplasm. The keratinized layer of ortho- and parakeratinized epithelium is built of two types of cells such as electron dark and light cells, which undergo exfoliation. The basic difference between the keratinized epithelia is the presence of flattened cell nuclei in the keratinized layer of the parakeratinized epithelium. The differentiating feature is also an arrangement of keratin fibers in the cell cytoplasm of the keratinized layer. The analysis of the thickness of the epithelium and the keratinized layer, indicated differences between keratinized epithelia, which result from two variants of performing protective functions, either through a thick keratinized layer or by a higher epithelium. Differences in the ultrastructure of the ortho- and parakeratinized epithelium are associated with mechanical functions of the epithelium resulting from different forces acting on the tongue during feeding activities. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrophobic Polystyrene Passivation Layer for Simultaneously Improved Efficiency and Stability in Perovskite Solar Cells.

PubMed

Li, Minghua; Yan, Xiaoqin; Kang, Zhuo; Huan, Yahuan; Li, Yong; Zhang, Ruxiao; Zhang, Yue

2018-06-06

The major restraint for the commercialization of the high-performance hybrid metal halide perovskite solar cells is the long-term stability, especially at the infirm interface between the perovskite film and organic charge-transfer layer. Recently, engineering the interface between the perovskite and spiro-OMeTAD becomes an effective strategy to simultaneously improve the efficiency and stability in the perovskite solar cells. In this work, we demonstrated that introducing an interfacial polystyrene layer between the perovskite film and spiro-OMeTAD layer can effectively improve the perovskite solar cells photovoltaic performance. The inserted polystyrene layer can passivate the interface traps and defects effectively and decrease the nonradiative recombination, leading to enhanced photoluminescence intensity and carrier lifetime, without compromising the carrier extraction and transfer. Under the optimized condition, the perovskite solar cells with the polystyrene layer achieve an enhanced average power efficiency of about 19.61% (20.46% of the best efficiency) from about 17.63% with negligible current density-voltage hysteresis. Moreover, the optimized perovskite solar cells with the hydrophobic polystyrene layer can maintain about 85% initial efficiency after 2 months storage in open air conditions without encapsulation.

Atomically Thin-Layered Molybdenum Disulfide (MoS2) for Bulk-Heterojunction Solar Cells.

PubMed

Singh, Eric; Kim, Ki Seok; Yeom, Geun Young; Nalwa, Hari Singh

2017-02-01

Transition metal dichalcogenides (TMDs) are becoming significant because of their interesting semiconducting and photonic properties. In particular, TMDs such as molybdenum disulfide (MoS 2 ), molybdenum diselenide (MoSe 2 ), tungsten disulfide (WS 2 ), tungsten diselenide (WSe 2 ), titanium disulfide (TiS 2 ), tantalum sulfide (TaS 2 ), and niobium selenide (NbSe 2 ) are increasingly attracting attention for their applications in solar cell devices. In this review, we give a brief introduction to TMDs with a focus on MoS 2 ; and thereafter, emphasize the role of atomically thin MoS 2 layers in fabricating solar cell devices, including bulk-heterojunction, organic, and perovskites-based solar cells. Layered MoS 2 has been used as the hole-transport layer (HTL), electron-transport layer (ETL), interfacial layer, and protective layer in fabricating heterojunction solar cells. The trilayer graphene/MoS 2 /n-Si solar cell devices exhibit a power-conversion efficiency of 11.1%. The effects of plasma and chemical doping on the photovoltaic performance of MoS 2 solar cells have been analyzed. After doping and electrical gating, a power-conversion efficiency (PCE) of 9.03% has been observed for the MoS 2 /h-BN/GaAs heterostructure solar cells. The MoS 2 -containing perovskites-based solar cells show a PCE as high as 13.3%. The PCE of MoS 2 -based organic solar cells exceeds 8.40%. The stability of MoS 2 solar cells measured under ambient conditions and light illumination has been discussed. The MoS 2 -based materials show a great potential for solar cell devices along with high PCE; however, in this connection, their long-term environmental stability is also of equal importance for commercial applications.

Properties of nanocrystalline Si layers embedded in structure of solar cell

NASA Astrophysics Data System (ADS)

Jurečka, Stanislav; Imamura, Kentaro; Matsumoto, Taketoshi; Kobayashi, Hikaru

2017-12-01

Suppression of spectral reflectance from the surface of solar cell is necessary for achieving a high energy conversion efficiency. We developed a simple method for forming nanocrystalline layers with ultralow reflectance in a broad range of wavelengths. The method is based on metal assisted etching of the silicon surface. In this work, we prepared Si solar cell structures with embedded nanocrystalline layers. The microstructure of embedded layer depends on the etching conditions. We examined the microstructure of the etched layers by a transmission electron microscope and analysed the experimental images by statistical and Fourier methods. The obtained results provide information on the applied treatment operations and can be used to optimize the solar cell forming procedure.

Wrapped optoelectronic devices and methods for making same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curran, Seamus; Dias, Sampath; Alley, Nigel

In various embodiments, optoelectronic devices are described herein. The optoelectronic device may include an optoelectronic cell arranged so as to wrap around a central axis wherein the cell includes a first conductive layer, a semi-conductive layer disposed over and in electrical communication with the first conductive layer, and a second conductive layer disposed over and in electrical communication with the semi-conductive layer. In various embodiments, methods for making optoelectronic devices are described herein. The methods may include forming an optoelectronic cell while flat and wrapping the optoelectronic cell around a central axis. The optoelectronic devices may be photovoltaic devices. Alternatively,more » the optoelectronic devices may be organic light emitting diodes.« less

Annealing and anomalous high-energy electron irradiation effects in low-cost silicon N+P solar cells

NASA Technical Reports Server (NTRS)

Garlick, G. F. J.; Kachare, A. H.

1981-01-01

Silicon solar cells of N(+)P type were subjected to 1 MeV electron irradiation (up to 10 to the 16th electrons/sq cm) and then annealed at 450 C for 20 min or annealed with no electron irradiation. Electron irradiation resulted in a degradation of longer wavelength cell response, but produced a marked enhancement of response at shorter wavelengths with a peak change of 40% at 0.44 microns. Subsequent thermal anneal at 450 C reduced the long-wavelength degradation, but enhancement at shorter wavelengths persisted. Excitation at the shorter wavelengths was in the N(+)-diffused layer and in the junction region of the cell. Anneal of unirradiated cells produced shorter-wavelength enhancement with a similar peaking at 0.44 microns, but with a relative change of only 20%. More enhancement was produced in the longer wavelength region (up to 0.8 microns). These effects in the different cell regions are explained by a decrease in the interstitial oxygen-impurity complexes (deep recombination levels) and the formation of substantial oxygen-silicon vacancy centers (donors).

Novel Flexible Plastic-Based Solar Cells

DTIC Science & Technology

2012-10-19

Fabrication of newly designed hybrid solar cells that are composed of a electron transport layer ( TiO2 ), a light sensitizing layer (NCs), and a hole...coating and spraying techniques, to produce broad-band light harvesting hybrid solar cells with bulk and layered heterojunction of inorganic...fabrication of hybrid bulk heterojunction photovoltaic cell using a blend film of polymer-inorganic NCs, 2) Fabrication of newly designed hybrid solar

AcmB Is an S-Layer-Associated β-N-Acetylglucosaminidase and Functional Autolysin in Lactobacillus acidophilus NCFM

PubMed Central

Johnson, Brant R.

2016-01-01

ABSTRACT Autolysins, also known as peptidoglycan hydrolases, are enzymes that hydrolyze specific bonds within bacterial cell wall peptidoglycan during cell division and daughter cell separation. Within the genome of Lactobacillus acidophilus NCFM, there are 11 genes encoding proteins with peptidoglycan hydrolase catalytic domains, 9 of which are predicted to be functional. Notably, 5 of the 9 putative autolysins in L. acidophilus NCFM are S-layer-associated proteins (SLAPs) noncovalently colocalized along with the surface (S)-layer at the cell surface. One of these SLAPs, AcmB, a β-N-acetylglucosaminidase encoded by the gene lba0176 (acmB), was selected for functional analysis. In silico analysis revealed that acmB orthologs are found exclusively in S-layer- forming species of Lactobacillus. Chromosomal deletion of acmB resulted in aberrant cell division, autolysis, and autoaggregation. Complementation of acmB in the ΔacmB mutant restored the wild-type phenotype, confirming the role of this SLAP in cell division. The absence of AcmB within the exoproteome had a pleiotropic effect on the extracellular proteins covalently and noncovalently bound to the peptidoglycan, which likely led to the observed decrease in the binding capacity of the ΔacmB strain for mucin and extracellular matrices fibronectin, laminin, and collagen in vitro. These data suggest a functional association between the S-layer and the multiple autolysins noncovalently colocalized at the cell surface of L. acidophilus NCFM and other S-layer-producing Lactobacillus species. IMPORTANCE Lactobacillus acidophilus is one of the most widely used probiotic microbes incorporated in many dairy foods and dietary supplements. This organism produces a surface (S)-layer, which is a self-assembling crystalline array found as the outermost layer of the cell wall. The S-layer, along with colocalized associated proteins, is an important mediator of probiotic activity through intestinal adhesion and modulation of the mucosal immune system. However, there is still a dearth of information regarding the basic cellular and evolutionary function of S-layers. Here, we demonstrate that multiple autolysins, responsible for breaking down the cell wall during cell division, are associated with the S-layer. Deletion of the gene encoding one of these S-layer-associated autolysins confirmed its autolytic role and resulted in reduced binding capacity to mucin and intestinal extracellular matrices. These data suggest a functional association between the S-layer and autolytic activity through the extracellular presentation of autolysins. PMID:27422832

AcmB Is an S-Layer-Associated β-N-Acetylglucosaminidase and Functional Autolysin in Lactobacillus acidophilus NCFM.

PubMed

Johnson, Brant R; Klaenhammer, Todd R

2016-09-15

Autolysins, also known as peptidoglycan hydrolases, are enzymes that hydrolyze specific bonds within bacterial cell wall peptidoglycan during cell division and daughter cell separation. Within the genome of Lactobacillus acidophilus NCFM, there are 11 genes encoding proteins with peptidoglycan hydrolase catalytic domains, 9 of which are predicted to be functional. Notably, 5 of the 9 putative autolysins in L. acidophilus NCFM are S-layer-associated proteins (SLAPs) noncovalently colocalized along with the surface (S)-layer at the cell surface. One of these SLAPs, AcmB, a β-N-acetylglucosaminidase encoded by the gene lba0176 (acmB), was selected for functional analysis. In silico analysis revealed that acmB orthologs are found exclusively in S-layer- forming species of Lactobacillus Chromosomal deletion of acmB resulted in aberrant cell division, autolysis, and autoaggregation. Complementation of acmB in the ΔacmB mutant restored the wild-type phenotype, confirming the role of this SLAP in cell division. The absence of AcmB within the exoproteome had a pleiotropic effect on the extracellular proteins covalently and noncovalently bound to the peptidoglycan, which likely led to the observed decrease in the binding capacity of the ΔacmB strain for mucin and extracellular matrices fibronectin, laminin, and collagen in vitro These data suggest a functional association between the S-layer and the multiple autolysins noncovalently colocalized at the cell surface of L. acidophilus NCFM and other S-layer-producing Lactobacillus species. Lactobacillus acidophilus is one of the most widely used probiotic microbes incorporated in many dairy foods and dietary supplements. This organism produces a surface (S)-layer, which is a self-assembling crystalline array found as the outermost layer of the cell wall. The S-layer, along with colocalized associated proteins, is an important mediator of probiotic activity through intestinal adhesion and modulation of the mucosal immune system. However, there is still a dearth of information regarding the basic cellular and evolutionary function of S-layers. Here, we demonstrate that multiple autolysins, responsible for breaking down the cell wall during cell division, are associated with the S-layer. Deletion of the gene encoding one of these S-layer-associated autolysins confirmed its autolytic role and resulted in reduced binding capacity to mucin and intestinal extracellular matrices. These data suggest a functional association between the S-layer and autolytic activity through the extracellular presentation of autolysins. Copyright © 2016 Johnson and Klaenhammer.

Alterations of the outer retina in non-arteritic anterior ischaemic optic neuropathy detected using spectral-domain optical coherence tomography.

PubMed

Ackermann, Philipp; Brachert, Maike; Albrecht, Philipp; Ringelstein, Marius; Finis, David; Geerling, Gerd; Aktas, Orhan; Guthoff, Rainer

2017-07-01

A characteristic disease pattern may be reflected by retinal layer thickness changes in non-arteritic anterior ischaemic optic neuropathy measured using spectraldomain optical coherence tomography. Retinal layer segmentation is enabled by advanced software. In this study, retinal layer thicknesses in acute and chronic non-arteritic anterior ischaemic optic neuropathy were compared. A single-centre cross-sectional analysis was used. A total of 27 patients (20 age-matched healthy eyes) were included: 14 with acute (<7 days) and 13 patients with chronic non-arteritic anterior ischaemic optic neuropathy. Macular volume and 12° peripapillary ring optical coherence tomography scans were used. The peripapillary thicknesses of the following layers were determined by manual segmentation: retinal nerve fibres, ganglion cells + inner plexiform layer, inner nuclear layer + outer plexiform layer, outer nuclear layer + inner segments of the photoreceptors and outer segments of the photoreceptors to Bruch's membrane. Macular retinal layer thicknesses were automatically determined in volume cubes centred on the fovea. Peripapillary retinal swelling in acute nonarteritic anterior ischaemic optic neuropathy was attributable to retinal nerve fibre layer, ganglion cell layer/inner plexiform layer and outer nuclear layer/segments of the photoreceptors thickening. In chronic cases, peripapillary retinal nerve fibre layer, macular ganglion cell layer and inner plexiform layer thinning were observed. In acute non-arteritic anterior ischaemic optic neuropathy, the inner and outer peripapillary retinal layers are affected by thickness changes. In chronic cases, atrophy of the ganglion cells and their axons and dendrites is evident by inner retinal layer thinning. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Striate cortical contribution to the transcorneal electrically evoked response of the visual system.

PubMed

Shimazu, K; Miyake, Y; Fukatsu, Y; Watanabe, S

1996-01-01

Analyses of current-source-density (CSD) and multiple unit activity (MUA) in area 17 of the cat were performed to determine the sources of the cortical transcorneal electrically evoked response. Cortical field potential, CSD and MUA profiles were obtained with multi-electrodes. CSD findings include: current sinks (inward cell membrane current) within 20 ms latency, in layers 4 and 6 of the striate cortex; current sinks corresponding to N3 (negative component of the EER; latency, 35 ms) in layer 4 and lower layer 3 with current sources (outward cell membrane current) for N3 in the supragranular layers; current sinks with latency over 40 ms in the supragranular layers. In the layers 4 and 6, simultaneous MUA was seen. When the stimulus frequency was increased or with dual stimulation, the N3 current sinks were decreased. This indicates that N1 (latency, 9 ms) and N2 (latency, 20 ms) reflect near-field potentials in layers 4 and 6, generated by geniculocortical afferents, and that N3 is a post- and polysynaptic component. It is also suggested that dipoles composed of cell bodies and the apical dendrites of pyramidal cells of layer 3, generated by satellite cells in layer 4, play a major role in generating N3.

Effect of incorporation of silver nanoparticles in PEDOT:PSS layer on performance of organic solar cell

NASA Astrophysics Data System (ADS)

Singh, Joginder; Nirwal, Varun Singh; Bhatnagar, P. K.; Peta, Koteswara Rao

2018-05-01

Solution processable organic solar cells have attracted significant interest in scientific community due to their easy processability, flexibility and eco friendly fabrication. In these organic solar cells structure, PEDOT:PSS layer has major importance as it used as hole transporting layer. In the present work, we have analyzed the effect of incorporation of silver nanoparticles (AgNPs) in PEDOT:PSS layer for P3HT:PCBM based organic solar cells. The presence of Ag nanoparticles in PEDOT:PSS film is confirmed by atomic force microscopy (AFM) images. It has been observed that PEDOT:PSS layer with AgNPs has ˜5.4% more transmittance than PEDOT:PSS layer in most of the visible region, which helps in reaching more light on active layer. Finally, solar cell with structure ITO/PEDOT:PSS:AgNPs/Al is fabricated and J-V characteristics are plotted under illumination. It is observed that there is a significant (˜10%) enhancement in short circuit current and slight increment in open circuit voltage with addition of AgNPs in PEDOT:PSS layer. The calculated value of power conversion efficiency (PCE) of fabricated device without AgNPs in PEDOT:PSS was 1.67%, which increased to 2.02% after addition of AgNPs in PEDOT:PSS layer.

Status epilepticus increases mature granule cells in the molecular layer of the dentate gyrus in rats★

PubMed Central

Liang, Zhaoliang; Gao, Fei; Wang, Fajun; Wang, Xiaochen; Song, Xinyu; Liu, Kejing; Zhan, Ren-Zhi

2013-01-01

Enhanced neurogenesis in the dentate gyrus of the hippocampus following seizure activity, especially status epilepticus, is associated with ectopic residence and aberrant integration of newborn granule cells. Hilar ectopic granule cells may be detrimental to the stability of dentate circuitry by means of their electrophysiological properties and synaptic connectivity. We hypothesized that status epilepticus also increases ectopic granule cells in the molecular layer. Status epilepticus was induced in male Sprague-Dawley rats by intraperitoneal injection of pilocarpine. Immunostaining showed that many doublecortin-positive cells were present in the molecular layer and the hilus 7 days after the induction of status epilepticus. At least 10 weeks after status epilepticus, the estimated number of cells positive for both prospero homeobox protein 1 and neuron-specific nuclear protein in the hilus was significantly increased. A similar trend was also found in the molecular layer. These findings indicate that status epilepticus can increase the numbers of mature and ectopic newborn granule cells in the molecular layer. PMID:25206705

Monitoring the injured brain: registered, patient specific atlas models to improve accuracy of recovered brain saturation values

NASA Astrophysics Data System (ADS)

Clancy, Michael; Belli, Antonio; Davies, David; Lucas, Samuel J. E.; Su, Zhangjie; Dehghani, Hamid

2015-07-01

The subject of superficial contamination and signal origins remains a widely debated topic in the field of Near Infrared Spectroscopy (NIRS), yet the concept of using the technology to monitor an injured brain, in a clinical setting, poses additional challenges concerning the quantitative accuracy of recovered parameters. Using high density diffuse optical tomography probes, quantitatively accurate parameters from different layers (skin, bone and brain) can be recovered from subject specific reconstruction models. This study assesses the use of registered atlas models for situations where subject specific models are not available. Data simulated from subject specific models were reconstructed using the 8 registered atlas models implementing a regional (layered) parameter recovery in NIRFAST. A 3-region recovery based on the atlas model yielded recovered brain saturation values which were accurate to within 4.6% (percentage error) of the simulated values, validating the technique. The recovered saturations in the superficial regions were not quantitatively accurate. These findings highlight differences in superficial (skin and bone) layer thickness between the subject and atlas models. This layer thickness mismatch was propagated through the reconstruction process decreasing the parameter accuracy.

Chondrocyte Differentiation of Human Endometrial Gland-Derived MSCs in Layered Cell Sheets

PubMed Central

Shimizu, Tatsuya; Yamato, Masayuki; Umezawa, Akihiro; Okano, Teruo

2013-01-01

Recently, regenerative medicine using engineered three-dimensional (3D) tissues has been focused. In the fields of cell therapy and regenerative medicine, mesenchymal stem cells (MSCs) are attractive autologous cell sources. While, in bioengineered tissues, a 3D environment may affect the differentiation of the stem cells, little is known regarding the effect of 3D environment on cellular differentiation. In this study, MSC differentiation in in vitro 3D tissue models was assessed by human endometrial gland-derived MSCs (hEMSCs) and cell sheet technology. hEMSC sheets were layered into cell-dense 3D tissues and were cultured on porous membranes. The tissue sections revealed that chondrocyte-like cells were found within the multilayered cell sheets even at 24 h after layering. Immunostainings of chondrospecific markers were positive within those cell sheet constructs. In addition, sulfated glycosaminoglycan accumulation within the tissues increased in proportion to the numbers of layered cell sheets. The findings suggested that a high cell density and hypoxic environment in 3D tissues by layering cell sheets might accelerate a rapid differentiation of hEMSCs into chondrocytes without the help of chondro-differentiation reagents. These tissue models using cell sheets would give new insights to stem cell differentiation in 3D environment and contribute to the future application of stem cells to cartilage regenerative therapy. PMID:24348153

Nano-crystalline thin and nano-particulate thick TiO{sub 2} layer: Cost effective sequential deposition and study on dye sensitized solar cell characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, P.; Sengupta, D.; CSIR-Central Mechanical Engineering Research Institute, Academy of Scientific and Innovative Research

Highlights: • Thin TiO{sub 2} layer is deposited on conducting substrate using sol–gel based dip coating. • TiO{sub 2} nano-particles are synthesized using hydrothermal route. • Thick TiO{sub 2} particulate layer is deposited on prepared thin layer. • Dye sensitized solar cells are made using thin and thick layer based photo-anode. • Introduction of thin layer in particulate photo-anode improves the cell efficiency. - Abstract: A compact thin TiO{sub 2} passivation layer is introduced between the mesoporous TiO{sub 2} nano-particulate layer and the conducting glass substrate to prepare photo-anode for dye-sensitized solar cell (DSSC). In order to understand the effectmore » of passivation layer, other two DSSCs are also developed separately using TiO{sub 2} nano-particulate and compact thin film based photo-anodes. Nano-particles are prepared using hydrothermal synthesis route and the compact passivation layer is prepared by simply dip coating the precursor sol prepared through wet chemical route. The TiO{sub 2} compact layer and the nano-particles are characterised in terms of their micro-structural features and phase formation behavior. It is found that introduction of a compact TiO{sub 2} layer in between the mesoporous TiO{sub 2} nano-particulate layer and the conducting substrate improves the solar to electric conversion efficiency of the fabricated cell. The dense thin passivation layer is supposed to enhance the photo-excited electron transfer and prevent the recombination of photo-excited electrons.« less

Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding

NASA Astrophysics Data System (ADS)

Czarnowska, Elżbieta; Borowski, Tomasz; Sowińska, Agnieszka; Lelątko, Józef; Oleksiak, Justyna; Kamiński, Janusz; Tarnowski, Michał; Wierzchoń, Tadeusz

2015-04-01

NiTi shape memory alloys are used for bone and cardiological implants. However, on account of the metallosis effect, i.e. the release of the alloy elements into surrounding tissues, they are subjected to various surface treatment processes in order to improve their corrosion resistance and biocompatibility without influencing the required shape memory properties. In this paper, the microstructure, topography and morphology of TiN surface layer on NiTi alloy, and corrosion resistance, both before and after nitriding in low-temperature plasma at 290 °C, are presented. Examinations with the use of the potentiodynamic and electrochemical impedance spectroscopy methods were carried out and show an increase of corrosion resistance in Ringer's solution after glow-discharge nitriding. This surface titanium nitride layer also improved the adhesion of platelets and the proliferation of osteoblasts, which was investigated in in vitro experiments with human cells. Experimental data revealed that nitriding NiTi shape memory alloy under low-temperature plasma improves its properties for bone implant applications.

Charge transport in quantum dot organic solar cells with Si quantum dots sandwiched between poly(3-hexylthiophene) (P3HT) absorber and bathocuproine (BCP) transport layers

NASA Astrophysics Data System (ADS)

Verma, Upendra Kumar; Kumar, Brijesh

2017-10-01

We have modeled a multilayer quantum dot organic solar cell that explores the current-voltage characteristic of the solar cell whose characteristics can be tuned by varying the fabrication parameters of the quantum dots (QDs). The modeled device consists of a hole transport layer (HTL) which doubles up as photon absorbing layer, several quantum dot layers, and an electron transport layer (ETL). The conduction of charge carriers in HTL and ETL has been modeled by the drift-diffusion transport mechanism. The conduction and recombination in the quantum dot layers are described by a system of coupled rate equations incorporating tunneling and bimolecular recombination. Analysis of QD-solar cells shows improved device performance compared to the similar bilayer and trilayer device structures without QDs. Keeping other design parameters constant, solar cell characteristics can be controlled by the quantum dot layers. Bimolecular recombination coefficient of quantum dots is a prime factor which controls the open circuit voltage (VOC) without any significant reduction in short circuit current (JSC).

Macular versus Retinal Nerve Fiber Layer Parameters for Diagnosing Manifest Glaucoma: A Systematic Review of Diagnostic Accuracy Studies.

PubMed

Oddone, Francesco; Lucenteforte, Ersilia; Michelessi, Manuele; Rizzo, Stanislao; Donati, Simone; Parravano, Mariacristina; Virgili, Gianni

2016-05-01

Macular parameters have been proposed as an alternative to retinal nerve fiber layer (RNFL) parameters to diagnose glaucoma. Comparing the diagnostic accuracy of macular parameters, specifically the ganglion cell complex (GCC) and ganglion cell inner plexiform layer (GCIPL), with the accuracy of RNFL parameters for detecting manifest glaucoma is important to guide clinical practice and future research. Studies using spectral domain optical coherence tomography (SD OCT) and reporting macular parameters were included if they allowed the extraction of accuracy data for diagnosing manifest glaucoma, as confirmed with automated perimetry or a clinician's optic nerve head (ONH) assessment. Cross-sectional cohort studies and case-control studies were included. The QUADAS 2 tool was used to assess methodological quality. Only direct comparisons of macular versus RNFL parameters (i.e., in the same study) were conducted. Summary sensitivity and specificity of each macular or RNFL parameter were reported, and the relative diagnostic odds ratio (DOR) was calculated in hierarchical summary receiver operating characteristic (HSROC) models to compare them. Thirty-four studies investigated macular parameters using RTVue OCT (Optovue Inc., Fremont, CA) (19 studies, 3094 subjects), Cirrus OCT (Carl Zeiss Meditec Inc., Dublin, CA) (14 studies, 2164 subjects), or 3D Topcon OCT (Topcon, Inc., Tokyo, Japan) (4 studies, 522 subjects). Thirty-two of these studies allowed comparisons between macular and RNFL parameters. Studies generally reported sensitivities at fixed specificities, more commonly 0.90 or 0.95, with sensitivities of most best-performing parameters between 0.65 and 0.75. For all OCT devices, compared with RNFL parameters, macular parameters were similarly or slightly less accurate for detecting glaucoma at the highest reported specificity, which was confirmed in analyses at the lowest specificity. Included studies suffered from limitations, especially the case-control study design, which is known to overestimate accuracy. However, this flaw is less relevant as a source of bias in direct comparisons conducted within studies. With the use of OCT, RNFL parameters are still preferable to macular parameters for diagnosing manifest glaucoma, but the differences are small. Because of high heterogeneity, direct comparative or randomized studies of OCT devices or OCT parameters and diagnostic strategies are essential. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Electrolytic etch for preventing electrical shorts in solar cells on polymer surfaces

DOEpatents

Weber, Michael F.

1991-10-08

A method for preventing shorts and shunts in solar cells having in order, an insulating substrate, a conductive metal layer on the substrate, an amorphous silicon layer and a transparent conductive layer. The method includes anodic etching of exposed portions of the metal layer after deposition of the amorphous silicon and prior to depositing the transparent conductive layer.

Amorphous silicon Schottky barrier solar cells incorporating a thin insulating layer and a thin doped layer

DOEpatents

Carlson, David E.

1980-01-01

Amorphous silicon Schottky barrier solar cells which incorporate a thin insulating layer and a thin doped layer adjacent to the junction forming metal layer exhibit increased open circuit voltages compared to standard rectifying junction metal devices, i.e., Schottky barrier devices, and rectifying junction metal insulating silicon devices, i.e., MIS devices.

Discharge cell for ozone generator

DOEpatents

Nakatsuka, Suguru

2000-01-01

A discharge cell for use in an ozone generator is provided which can suppress a time-related reduction in ozone concentration without adding a catalytic gas such as nitrogen gas to oxygen gas as a raw material gas. The discharge cell includes a pair of electrodes disposed in an opposed spaced relation with a discharge space therebetween, and a dielectric layer of a three-layer structure consisting of three ceramic dielectric layers successively stacked on at least one of the electrodes, wherein a first dielectric layer of the dielectric layer contacting the one electrode contains no titanium dioxide, wherein a second dielectric layer of the dielectric layer exposed to the discharge space contains titanium dioxide in a metal element ratio of not lower than 10 wt %.

N-Glycosylation Is Important for Proper Haloferax volcanii S-Layer Stability and Function.

PubMed

Tamir, Adi; Eichler, Jerry

2017-03-15

N-Glycosylation, the covalent linkage of glycans to select Asn residues of target proteins, is an almost universal posttranslational modification in archaea. However, whereas roles for N-glycosylation have been defined in eukarya and bacteria, the function of archaeal N-glycosylation remains unclear. Here, the impact of perturbed N-glycosylation on the structure and physiology of the haloarchaeon Haloferax volcanii was considered. Cryo-electron microscopy was used to examine right-side-out membrane vesicles prepared from cells of a parent strain and from strains lacking genes encoding glycosyltransferases involved in assembling the N-linked pentasaccharide decorating the surface layer (S-layer) glycoprotein, the sole component of the S-layer surrounding H. volcanii cells. Whereas a regularly repeating S-layer covered the entire surface of vesicles prepared from parent strain cells, vesicles from the mutant cells were only partially covered. To determine whether such N-glycosylation-related effects on S-layer assembly also affected cell function, the secretion of a reporter protein was addressed in the parent and N-glycosylation mutant strains. Compromised S-layer glycoprotein N-glycosylation resulted in impaired transfer of the reporter past the S-layer and into the growth medium. Finally, an assessment of S-layer glycoprotein susceptibility to added proteases in the mutants revealed that in cells lacking AglD, which is involved in adding the final pentasaccharide sugar, a distinct S-layer glycoprotein conformation was assumed in which the N-terminal region was readily degraded. Perturbed N-glycosylation thus affects S-layer glycoprotein folding. These findings suggest that H. volcanii could adapt to changes in its surroundings by modulating N-glycosylation so as to affect S-layer architecture and function. IMPORTANCE Long held to be a process unique to eukaryotes, it is now accepted that bacteria and archaea also perform N-glycosylation, namely, the covalent attachment of sugars to select asparagine residues of target proteins. Yet, while information on the importance of N-glycosylation in eukaryotes and bacteria is available, the role of this posttranslational modification in archaea remains unclear. Here, insight into the purpose of archaeal N-glycosylation was gained by addressing the surface layer (S-layer) surrounding cells of the halophilic species Haloferax volcanii Relying on mutant strains defective in N-glycosylation, such efforts revealed that compromised N-glycosylation affected S-layer integrity and the transfer of a secreted reporter protein across the S-layer into the growth medium, as well as the conformation of the S-layer glycoprotein, the sole component of the S-layer. Thus, by modifying N-glycosylation, H. volcanii cells can change how they interact with their surroundings. Copyright © 2017 American Society for Microbiology.

Reprogramming of fibroblasts from older women with pelvic floor disorders alters cellular behavior associated with donor age.

PubMed

Wen, Yan; Wani, Prachi; Zhou, Lu; Baer, Tom; Phadnis, Smruti Madan; Reijo Pera, Renee A; Chen, Bertha

2013-02-01

We aimed to derive induced pluripotent stem cell (iPSC) lines from vaginal fibroblasts from older women with pelvic organ prolapse. We examined the effect of donor age on iPSCs and on the cells redifferentiated from these iPSCs. Vaginal fibroblasts were isolated from younger and older subjects for reprogramming. iPSCs were generated simultaneously using an excisable polycistronic lentiviral vector expressing Oct4, Klf4, Sox2, and cMyc. The pluripotent markers of iPSCs were confirmed by immunocytochemistry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Spectral karyotyping was performed. The ability of the iPSCs to differentiate into three germ layers was confirmed by embryoid body and teratoma formation. Senescence marker (p21, p53, and Bax) expressions were determined by qRT-PCR and Western blot. The iPSCs were redifferentiated to fibroblasts and were evaluated with senescence-associated β-galactosidase (SA) activity and mitotic index using time-lapse dark-field microscopy. iPSCs derived from both the younger and older subjects expressed pluripotency markers and showed normal karyotype and positive teratoma assays. There was no significant difference in expression of senescence and apoptosis markers (p21, p53, and Bax) in iPSCs derived from the younger subject compared with the older subject. Furthermore, fibroblasts redifferentiated from these iPSCs did not differ in SA activity or mitotic index. We report successful derivation of iPSCs from women with pelvic organ prolapse. Older age did not interfere with successful reprogramming. Donor age differences were not observed in these iPSCs using standard senescence markers, and donor age did not appear to affect cell mitotic activity in fibroblasts redifferentiated from iPSCs.

Theoretical study of ZnS/CdS bi-layer for thin-film CdTe solar cell

NASA Astrophysics Data System (ADS)

Mohamed, H. A.; Mohamed, A. S.; Ali, H. M.

2018-05-01

The performance of CdTe solar cells is strongly limited by the thickness of CdS window layer. A higher short-circuit current density might be achieved by decreasing the thickness of CdS layer as a result of reducing the absorption losses that take place in this layer. However, it is difficult to obtain uniform and pin-hole free CdS layers thinner than 50 nm. This problem can be solved through increasing the band gap of the window layer by adding a wide band gap semiconductor such as ZnS. In this work, bi-layer ZnS/CdS film was studied as an improved window layer of ITO/ZnS/CdS/CdTe solar cell. The total thickness of ZnS/CdS layer was taken about 60 nm. The effect of optical losses due to reflection at different interfaces in the cell and absorption in ITO, ZnS, CdS as well as the recombination loss have been studied. Finally, the effects of the recombination losses in the space-charge region and the reflectivity from the back contact were taken into accounts. The results revealed that the optical losses of 23% were achieved at 60 nm thickness of CdS and theses losses minimized to 18% when ZnS layer of 30 nm thickness was added to CdS layer. The minimum optical and recombination losses of about 26% were obtained at 1 ns of electron life-time and ∼0.4 μm width of the space-charge region. The maximum efficiency of 18.5% was achieved for ITO/CdS/CdTe cell and the efficiency increased up to 20% for ITO/ZnS/CdS/CdTe cell.

[Preparation of acellular matrix from antler cartilage and its biological compatibility].

PubMed

Fu, Jing; Zhang, Wei; Zhang, Aiwu; Ma, Lijuan; Chu, Wenhui; Li, Chunyi

2017-06-01

To study the feasibility of acellular matrix materials prepared from deer antler cartilage and its biological compatibility so as to search for a new member of the extracellular matrix family for cartilage regeneration. The deer antler mesenchymal (M) layer tissue was harvested and treated through decellular process to prepare M layer acellular matrix; histologic observation and detection of M layer acellular matrix DNA content were carried out. The antler stem cells [antlerogenic periosteum (AP) cells] at 2nd passage were labelled by fluorescent stains and by PKH26. Subsequently, the M layer acellular matrix and the AP cells at 2nd passage were co-cultured for 7 days; then the samples were transplanted into nude mice to study the tissue compatibility of M layer acellular matrix in the living animals. HE and DAPI staining confirmed that the M layer acellular matrix did not contain nucleus; the DNA content of the M layer acellular matrix was (19.367±5.254) ng/mg, which was significantly lower than that of the normal M layer tissue [(3 805.500±519.119) ng/mg]( t =12.630, P =0.000). In vitro co-culture experiments showed that AP cells could adhere to or even embedded in the M layer acellular matrix. Nude mice transplantation experiments showed that the introduced AP cells could proliferate and induce angiogenesis in the M layer acellular matrix. The deer antler cartilage acellular matrix is successfully prepared. The M layer acellular matrix is suitable for adhesion and proliferation of AP cells in vitro and in vivo , and it has the function of stimulating angiogenesis. This model for deer antler cartilage acellular matrix can be applied in cartilage tissue engineering in the future.

Systems and methods for advanced ultra-high-performance InP solar cells

DOEpatents

Wanlass, Mark

2017-03-07

Systems and Methods for Advanced Ultra-High-Performance InP Solar Cells are provided. In one embodiment, an InP photovoltaic device comprises: a p-n junction absorber layer comprising at least one InP layer; a front surface confinement layer; and a back surface confinement layer; wherein either the front surface confinement layer or the back surface confinement layer forms part of a High-Low (HL) doping architecture; and wherein either the front surface confinement layer or the back surface confinement layer forms part of a heterointerface system architecture.

Photovoltaic cell with nano-patterned substrate

DOEpatents

Cruz-Campa, Jose Luis; Zhou, Xiaowang; Zubia, David

2016-10-18

A photovoltaic solar cell comprises a nano-patterned substrate layer. A plurality of nano-windows are etched into an intermediate substrate layer to form the nano-patterned substrate layer. The nano-patterned substrate layer is positioned between an n-type semiconductor layer composed of an n-type semiconductor material and a p-type semiconductor layer composed of a p-type semiconductor material. Semiconductor material accumulates in the plurality of nano-windows, causing a plurality of heterojunctions to form between the n-type semiconductor layer and the p-type semiconductor layer.

Amorphous semiconductor solar cell

DOEpatents

Dalal, Vikram L.

1981-01-01

A solar cell comprising a back electrical contact, amorphous silicon semiconductor base and junction layers and a top electrical contact includes in its manufacture the step of heat treating the physical junction between the base layer and junction layer to diffuse the dopant species at the physical junction into the base layer.

Interfacial Energy Alignment at the ITO/Ultra-Thin Electron Selective Dielectric Layer Interface and Its Effect on the Efficiency of Bulk-Heterojunction Organic Solar Cells.

PubMed

Itoh, Eiji; Goto, Yoshinori; Saka, Yusuke; Fukuda, Katsutoshi

2016-04-01

We have investigated the photovoltaic properties of an inverted bulk heterojunction (BHJ) cell in a device with an indium-tin-oxide (ITO)/electron selective layer (ESL)/P3HT:PCBM active layer/MoOx/Ag multilayered structure. The insertion of only single layer of poly(diallyl-dimethyl-ammonium chloride) (PDDA) cationic polymer film (or poly(ethyleneimine) (PEI) polymeric interfacial dipole layer) and titanium oxide nanosheet (TN) films as an ESL effectively improved cell performance. Abnormal S-shaped curves were observed in the inverted BHJ cells owing to the contact resistance across the ITO/active layer interface and the ITO/PDDA/TN/active layer interface. The series resistance across the ITO/ESL interface in the inverted BHJ cell was successfully reduced using an interfacial layer with a positively charged surface potential with respect to ITO base electrode. The positive dipole in PEI and the electronic charge phenomena at the electrophoretic deposited TN (ED-TN) films on ITO contributed to the reduction of the contact resistance at the electrode interface. The surface potential measurement revealed that the energy alignment by the transfer of electronic charges from the ED-TN to the base electrodes. The insertion of the ESL with a large positive surface potential reduced the potential barrier for the electron injection at ITO/TN interface and it improved the photovoltaic properties of the inverted cell with an ITO/TN/active layer/MoOx/Ag structure.

In vitro cytotoxicity of Fe-Cr-Nb-B magnetic nanoparticles under high frequency electromagnetic field

NASA Astrophysics Data System (ADS)

Chiriac, Horia; Petreus, Tudor; Carasevici, Eugen; Labusca, Luminita; Herea, Dumitru-Daniel; Danceanu, Camelia; Lupu, Nicoleta

2015-04-01

The heating potential, cytotoxicity, and efficiency of Fe68.2Cr11.5Nb0.3B20 magnetic nanoparticles (MNPs), as such or coated with a chitosan layer, to decrease the cell viability in a cancer cell culture model by using high frequency alternating magnetic fields (AMF) have been studied. The specific absorption rate varied from 215 W/g for chitosan-free MNPs to about 190 W/g for chitosan-coated ones, and an equilibrium temperature of 46 °C was reached when chitosan-coated MNPs were subjected to AMF. The chitosan-free Fe68.2Cr11.5Nb0.3B20 MNPs proved a good biocompatibility and low cytotoxicity in all testing conditions, while the chitosan-coated ones induced strong tumoricidal effects when a cell-particle simultaneous co-incubation approach was used. In high frequency AMF, the particle-mediated heat treatment has proved to be a critical cause for decreasing in vitro the viability of a cancer cell line.

Efficacy and connectivity of intracolumnar pairs of layer 2/3 pyramidal cells in the barrel cortex of juvenile rats

PubMed Central

Feldmeyer, Dirk; Lübke, Joachim; Sakmann, Bert

2006-01-01

Synaptically coupled layer 2/3 (L2/3) pyramidal neurones located above the same layer 4 barrel (‘barrel-related’) were investigated using dual whole-cell voltage recordings in acute slices of rat somatosensory cortex. Recordings were followed by reconstructions of biocytin-filled neurones. The onset latency of unitary EPSPs was 1.1 ± 0.4 ms, the 20–80% rise time was 0.7 ± 0.2 ms, the average amplitude was 1.0 ± 0.7 mV and the decay time constant was 15.7 ± 4.5 ms. The coefficient of variation (c.v.) of unitary EPSP amplitudes decreased with increasing EPSP peak and was 0.33 ± 0.18. Bursts of APs in the presynaptic pyramidal cell resulted in EPSPs that, over a wide range of frequencies (5–100 Hz), displayed amplitude depression. Anatomically the barrel-related pyramidal cells in the lower half of layer 2/3 have a long apical dendrite with a small terminal tuft, while pyramidal cells in the upper half of layer 2/3 have shorter and often more ‘irregularly’ shaped apical dendrites that branch profusely in layer 1. The number of putative excitatory synaptic contacts established by the axonal collaterals of a L2/3 pyramidal cell with a postsynaptic pyramidal cell in the same column varied between 2 and 4, with an average of 2.8 ± 0.7 (n = 8 pairs). Synaptic contacts were established predominantly on the basal dendrites at a mean geometric distance of 91 ± 47 μm from the pyramidal cell soma. L2/3-to-L2/3 connections formed a blob-like innervation domain containing 2.8 mm of the presynaptic axon collaterals with a bouton density of 0.3 boutons per μm axon. Within the supragranular layers of its home column a single L2/3 pyramidal cell established about 900 boutons suggesting that 270 pyramidal cells in layer 2/3 are innervated by an individual pyramidal cell. In turn, a single pyramidal cell received synaptic inputs from 270 other L2/3 pyramidal cells. The innervation domain of L2/3-to-L2/3 connections superimposes almost exactly with that of L4-to-L2/3 connections. This suggests that synchronous feed-forward excitation of L2/3 pyramidal cells arriving from layer 4 could be potentially amplified in layer 2/3 by feedback excitation within a column and then relayed to the neighbouring columns. PMID:16793907

Nanostructured GaAs solar cells via metal-assisted chemical etching of emitter layers.

PubMed

Song, Yunwon; Choi, Keorock; Jun, Dong-Hwan; Oh, Jungwoo

2017-10-02

GaAs solar cells with nanostructured emitter layers were fabricated via metal-assisted chemical etching. Au nanoparticles produced via thermal treatment of Au thin films were used as etch catalysts to texture an emitter surface with nanohole structures. Epi-wafers with emitter layers 0.5, 1.0, and 1.5 um in thickness were directly textured and a window layer removal process was performed before metal catalyst deposition. A nanohole-textured emitter layer provides effective light trapping capabilities, reducing the surface reflection of a textured solar cell by 11.0%. However, because the nanostructures have high surface area to volume ratios and large numbers of defects, various photovoltaic properties were diminished by high recombination losses. Thus, we have studied the application of nanohole structures to GaAs emitter solar cells and investigated the cells' antireflection and photovoltaic properties as a function of the nanohole structure and emitter thickness. Due to decreased surface reflection and improved shunt resistance, the solar cell efficiency increased from 4.25% for non-textured solar cells to 7.15% for solar cells textured for 5 min.

3D Printing of Human Tissue Mimics via Layer-by-Layer Assembly of Polymer/Hydrogel Biopapers

NASA Astrophysics Data System (ADS)

Ringeisen, Bradley

2015-03-01

The foundations of tissue engineering were built on two fundamental areas of research: cells and scaffolds. Multipotent cells and their derivatives are traditionally randomly seeded into sophisticated polymer or hydrogel scaffolds, ultimately with the goal of forming a tissue-like material through cell differentiation and cell-material interactions. One problem with this approach is that no matter how complex or biomimetic the scaffold is, the cells are still homogeneously distributed throughout this three dimensional (3D) material. Natural tissue is inherently heterogeneous on both a microscopic and macroscopic level. It also contains different types of cells in close proximity, extracellular matrix, voids, and a complex vascularized network. Recently developed 3D cell and organ printers may be able to enhance traditional tissue engineering experiments by building scaffolds layer-by-layer that are crafted to mimic the microscopic and macroscopic structure of natural tissue or organs. Over the past decade, my laboratory has developed a capillary-free, live cell printer termed biological laser printing, or BioLP. We find that printed cells do not express heat shock protein and retain >99% viability. Printed cells also incur no DNA strand fracture and preserve their ability to differentiate. Recent work has used a layer-by-layer approach, stacking sheets of hybrid polymer/hydrogel biopapers in conjunction with live cell printing to create 3D tissue structures. Our specific work is now focused on the blood-brain-barrier and air-lung interface and will be described during the presentation.

Highly efficient and stable inverted perovskite solar cell employing PEDOT:GO composite layer as a hole transport layer.

PubMed

Yu, Jae Choul; Hong, Ji A; Jung, Eui Dae; Kim, Da Bin; Baek, Soo-Min; Lee, Sukbin; Cho, Shinuk; Park, Sung Soo; Choi, Kyoung Jin; Song, Myoung Hoon

2018-01-18

The beneficial use of a hole transport layer (HTL) as a substitution for poly(3,4-ethlyenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is regarded as one of the most important approaches for improving the stability and efficiency of inverted perovskite solar cells. Here, we demonstrate highly efficient and stable inverted perovskite solar cells by applying a GO-doped PEDOT:PSS (PEDOT:GO) film as an HTL. The high performance of this solar cell stems from the excellent optical and electrical properties of the PEDOT:GO film, including a higher electrical conductivity, a higher work function related to the reduced contact barrier between the perovskite layer and the PEDOT:GO layer, enhanced crystallinity of the perovskite crystal, and suppressed leakage current. Moreover, the device with the PEDOT:GO layer showed excellent long-term stability in ambient air conditions. Thus, the enhancement in the efficiency and the excellent stability of inverted perovskite solar cells are promising for the eventual commercialization of perovskite optoelectronic devices.

Long-Wavelength Rupturing Instability in Surface-Tension-Driven Benard Convection

NASA Technical Reports Server (NTRS)

Swift, J. B.; Hook, Stephen J. Van; Becerril, Ricardo; McCormick, W. D.; Swinney, H. L.; Schatz, Michael F.

1999-01-01

A liquid layer with a free upper surface and heated from below is subject to thermocapillary-induced convective instabilities. We use very thin liquid layers (0.01 cm) to significantly reduce buoyancy effects and simulate Marangoni convection in microgravity. We observe thermocapillary-driven convection in two qualitatively different modes, short-wavelength Benard hexagonal convection cells and a long-wavelength interfacial rupturing mode. We focus on the long-wavelength mode and present experimental observations and theoretical analyses of the long-wavelength instability. Depending on the depths and thermal conductivities of the liquid and the gas above it, the interface can rupture downwards and form a dry spot or rupture upwards and form a high spot. Linear stability theory gives good agreement to the experimental measurements of onset as long as sidewall effects are taken into account. Nonlinear theory correctly predicts the subcritical nature of the bifurcation and the selection between the dry spot and high spots.

Physical stress and bacterial colonization

PubMed Central

Otto, Michael

2014-01-01

Bacterial surface colonizers are subject to a variety of physical stresses. During the colonization of human epithelia such as on the skin or the intestinal mucosa, bacteria mainly have to withstand the mechanical stress of being removed by fluid flow, scraping, or epithelial turnover. To that end, they express a series of molecules to establish firm attachment to the epithelial surface, such as fibrillar protrusions (pili) and surface-anchored proteins that bind to human matrix proteins. In addition, some bacteria – in particular gut and urinary tract pathogens – use internalization by epithelial cells and other methods such as directed inhibition of epithelial turnover to ascertain continued association with the epithelial layer. Furthermore, many bacteria produce multi-layered agglomerations called biofilms with a sticky extracellular matrix, providing additional protection from removal. This review will give an overview over the mechanisms human bacterial colonizers have to withstand physical stresses with a focus on bacterial adhesion. PMID:25212723

Stress-sensitive tissue regeneration in viscoelastic biomaterials subjected to modulated tensile strain.

PubMed

Belfiore, Laurence A; Floren, Michael L; Paulino, Alexandre T; Belfiore, Carol J

2011-09-01

This research contribution addresses the mechanochemistry of intra-tissue mass transfer for nutrients, oxygen, growth factors, and other essential ingredients that anchorage-dependent cells require for successful proliferation on biocompatible surfaces. The unsteady state reaction-diffusion equation (i.e., modified diffusion equation) is solved according to the von Kármán-Pohlhausen integral method of boundary layer analysis when nutrient consumption and tissue regeneration are stimulated by harmonically imposed stress. The mass balance with diffusion and stress-sensitive kinetics represents a rare example where the Damköhler and Deborah numbers appear together in an effort to simulate the development of mass transfer boundary layers in porous viscoelastic biomaterials. The Boltzmann superposition integral is employed to calculate time-dependent strain in terms of the real and imaginary components of dynamic compliance for viscoelastic solids that transmit harmonic excitation to anchorage-dependent cells. Rates of nutrient consumption under stress-free conditions are described by third-order kinetics which include local mass densities of nutrients, oxygen, and attached cells that maintain dynamic equilibrium with active protein sites in the porous matrix. Thinner nutrient mass transfer boundary layers are stabilized at shorter dimensionless diffusion times when the stress-free intra-tissue Damköhler number increases above its initial-condition-sensitive critical value. The critical stress-sensitive intra-tissue Damköhler number, above which it is necessary to consider the effect of harmonic strain on nutrient consumption and tissue regeneration, is proportional to the Deborah number and corresponds to a larger fraction of the stress-free intra-tissue Damköhler number in rigid biomaterials. Copyright © 2011 Elsevier B.V. All rights reserved.

Dermal Fibroblasts from Different Layers of Pig Skin Exhibit Different Profibrotic and Morphological Characteristics.

PubMed

Zuo, Yanhai; Yu, Xiaoping; Lu, Shuliang

2016-11-01

In vitro studies of human dermal fibroblast (DF) heterogeneity have long been reported, yet in vivo studies and related research on animals are rare. The objectives of the study were to determine whether the DFs of pigs exhibit heterogeneity and to identify an animal model for the in vivo study of DF heterogeneity. The skin of three female red Duroc pigs (FRDPs) was separated into six layers, and the second and fifth layers (i.e., the superficial and deep dermis) were used in the establishment of wound models and cell cultures. To create the wound models, 54 tongue-shaped flaps were created on one side of the dorsum, and the underlying dermis was then fully replaced with the superficial or deep dermis (the superficial and deep groups, respectively). Skin samples were harvested at postoperative weeks 1, 2, and 3 for measurements of the normal and wounded skin thicknesses. Cells cultured from the superficial and deep dermis (i.e., superficial and deep DFs) were subjected to quantitative estimation of collagen and electron microscopy. The wounded skin thickness in the deep group was significantly greater than that in the superficial group. In contrast with the long deep DFs, the superficial DFs were short and exhibited microvilli-like cell surface projections. Compared with the superficial DFs, the deep DFs exhibited a greater density of rough endoplasmic reticulum and produced significantly more collagen. Similar to humans, FRDPs exhibit DF heterogeneity and should thus be a good animal model for in vivo studies of DF heterogeneity. Anat Rec, 299:1585-1599, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Solution-processed small molecule:fullerene bulk-heterojunction solar cells: impedance spectroscopy deduced bulk and interfacial limits to fill-factors.

PubMed

Guerrero, Antonio; Loser, Stephen; Garcia-Belmonte, Germà; Bruns, Carson J; Smith, Jeremy; Miyauchi, Hiroyuki; Stupp, Samuel I; Bisquert, Juan; Marks, Tobin J

2013-10-21

Using impedance spectroscopy, we demonstrate that the low fill factor (FF) typically observed in small molecule solar cells is due to hindered carrier transport through the active layer and hindered charge transfer through the anode interfacial layer (IFL). By carefully tuning the active layer thickness and anode IFL in BDT(TDPP)2 solar cells, the FF is increased from 33 to 55% and the PCE from 1.9 to 3.8%. These results underscore the importance of simultaneously optimizing active layer thickness and IFL in small molecule solar cells.

Low temperature perovskite solar cells with an evaporated TiO 2 compact layer for perovskite silicon tandem solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bett, Alexander J.; Schulze, Patricia S. C.; Winkler, Kristina

Silicon-based tandem solar cells can overcome the efficiency limit of single junction silicon solar cells. Perovskite solar cells are particularly promising as a top cell in monolithic tandem devices due to their rapid development towards high efficiencies, a tunable band gap with a sharp optical absorption edge and a simple production process. In monolithic tandem devices, the perovskite solar cell is deposited directly on the silicon cell, requiring low-temperature processes (< 200 °C) to maintain functionality of under-lying layers of the silicon cell in case of highly efficient silicon hetero-junction (SHJ) bottom solar cell. In this work, we present amore » complete low-temperature process for perovskite solar cells including a mesoporous titanium oxide (TiO 2) scaffold - a structure yielding the highest efficiencies for single-junction perovskite solar cells. We show that evaporation of the compact TiO 2 hole blocking layer and ultra-violet (UV) curing for the mesoporous TiO 2 layer allows for good performance, comparable to high-temperature (> 500 °C) processes. With both manufacturing routes, we obtain short-circuit current densities (J SC) of about 20 mA/cm 2, open-circuit voltages (V OC) over 1 V, fill factors (FF) between 0.7 and 0.8 and efficiencies (n) of more than 15%. We further show that the evaporated TiO 2 layer is suitable for the application in tandem devices. The series resistance of the layer itself and the contact resistance to an indium doped tin oxide (ITO) interconnection layer between the two sub-cells are low. Additionally, the low parasitic absorption for wavelengths above the perovskite band gap allow a higher absorption in the silicon bottom solar cell, which is essential to achieve high tandem efficiencies.« less

Low temperature perovskite solar cells with an evaporated TiO 2 compact layer for perovskite silicon tandem solar cells

DOE PAGES

Bett, Alexander J.; Schulze, Patricia S. C.; Winkler, Kristina; ...

2017-09-21

Silicon-based tandem solar cells can overcome the efficiency limit of single junction silicon solar cells. Perovskite solar cells are particularly promising as a top cell in monolithic tandem devices due to their rapid development towards high efficiencies, a tunable band gap with a sharp optical absorption edge and a simple production process. In monolithic tandem devices, the perovskite solar cell is deposited directly on the silicon cell, requiring low-temperature processes (< 200 °C) to maintain functionality of under-lying layers of the silicon cell in case of highly efficient silicon hetero-junction (SHJ) bottom solar cell. In this work, we present amore » complete low-temperature process for perovskite solar cells including a mesoporous titanium oxide (TiO 2) scaffold - a structure yielding the highest efficiencies for single-junction perovskite solar cells. We show that evaporation of the compact TiO 2 hole blocking layer and ultra-violet (UV) curing for the mesoporous TiO 2 layer allows for good performance, comparable to high-temperature (> 500 °C) processes. With both manufacturing routes, we obtain short-circuit current densities (J SC) of about 20 mA/cm 2, open-circuit voltages (V OC) over 1 V, fill factors (FF) between 0.7 and 0.8 and efficiencies (n) of more than 15%. We further show that the evaporated TiO 2 layer is suitable for the application in tandem devices. The series resistance of the layer itself and the contact resistance to an indium doped tin oxide (ITO) interconnection layer between the two sub-cells are low. Additionally, the low parasitic absorption for wavelengths above the perovskite band gap allow a higher absorption in the silicon bottom solar cell, which is essential to achieve high tandem efficiencies.« less

Low cost fuel cell diffusion layer configured for optimized anode water management

DOEpatents

Owejan, Jon P; Nicotera, Paul D; Mench, Matthew M; Evans, Robert E

2013-08-27

A fuel cell comprises a cathode gas diffusion layer, a cathode catalyst layer, an anode gas diffusion layer, an anode catalyst layer and an electrolyte. The diffusion resistance of the anode gas diffusion layer when operated with anode fuel is higher than the diffusion resistance of the cathode gas diffusion layer. The anode gas diffusion layer may comprise filler particles having in-plane platelet geometries and be made of lower cost materials and manufacturing processes than currently available commercial carbon fiber substrates. The diffusion resistance difference between the anode gas diffusion layer and the cathode gas diffusion layer may allow for passive water balance control.

Expression of LIM-homeodomain transcription factors in the developing and mature mouse retina

PubMed Central

Balasubramanian, Revathi; Bui, Andrew; Ding, Qian; Gan, Lin

2014-01-01

LIM-homeodomain (LIM-HD) transcription factors have been extensively studied for their role in the development of the central nervous system. Their function is key to several developmental events like cell proliferation, differentiation and subtype specification. However, their roles in retinal neurogenesis remain largely unknown. Here we report a detailed expression study of LIM-HD transcription factors LHX9 and LHX2, LHX3 and LHX4, and LHX6 in the developing and mature mouse retina using immunohistochemistry and in situ hybridization techniques. We show that LHX9 is expressed during the early stages of development in the retinal ganglion cell layer and the inner nuclear layer. We also show that LHX9 is expressed in a subset of amacrine cells in the adult retina. LHX2 is known to be expressed in retinal progenitor cells during development and in Müller glial cells and a subset of amacrine cells in the adult retina. We found that the LHX2 subset of amacrine cells is not cholinergic and that a very few of LHX2 amacrine cells express calretinin. LHX3 and LHX4 are expressed in a subset of bipolar cells in the adult retina. LHX6 is expressed in cells in the ganglion cell layer and the neuroblast layer starting at embryonic stage 13.5 (E13.5) and continues to be expressed in cells in the ganglion cell layer and inner nuclear layer, postnatally, suggesting its likely expression in amacrine cells or a subset thereof. Taken together, our comprehensive assay of expression patterns of LIM-HD transcription factors during mouse retinal development will help further studies elucidating their biological functions in the differentiation of retinal cell subtypes. PMID:24333658

Coenzyme Q10 instilled as eye drops on the cornea reaches the retina and protects retinal layers from apoptosis in a mouse model of kainate-induced retinal damage.

PubMed

Lulli, Matteo; Witort, Ewa; Papucci, Laura; Torre, Eugenio; Schipani, Christian; Bergamini, Christian; Dal Monte, Massimo; Capaccioli, Sergio

2012-12-17

To evaluate if coenzyme Q10 (CoQ10) can protect retinal ganglion cells (RGCs) from apoptosis and, when instilled as eye drops on the cornea, if it can reach the retina and exert its antiapoptotic activity in this area in a mouse model of kainate (KA)-induced retinal damage. Rat primary or cultured RGCs were subjected to glutamate (50 μM) or chemical hypoxia (Antimycin A, 200 μM) or serum withdrawal (FBS, 0.5%) in the presence or absence of CoQ10 (10 μM). Cell viability was evaluated by light microscopy and fluorescence-activated cell sorting analyses. Apoptosis was evaluated by caspase 3/7 activity and mitochondrion depolarization tetramethylrhodamine ethyl ester analysis. CoQ10 transfer to the retina following its instillation as eye drops on the cornea was quantified by HPLC. Retinal protection by CoQ10 (10 μM) eye drops instilled on the cornea was then evaluated in a mouse model of KA-induced excitotoxic retinal cell apoptosis by cleaved caspase 3 immunohistofluorescence, caspase 3/7 activity assays, and quantification of inhibition of RGC loss. CoQ10 significantly increased viable cells by preventing RGC apoptosis. Furthermore, when topically applied as eye drops to the cornea, it reached the retina, thus substantially increasing local CoQ10 concentration and protecting retinal layers from apoptosis. The ability of CoQ10 eye drops to protect retinal cells from apoptosis in the mouse model of KA-induced retinal damage suggests that topical CoQ10 may be evaluated in designing therapies for treating apoptosis-driven retinopathies.

β‐Endorphin, Met‐enkephalin and corresponding opioid receptors within synovium of patients with joint trauma, osteoarthritis and rheumatoid arthritis

PubMed Central

Mousa, Shaaban A; Straub, Rainer H; Schäfer, Michael; Stein, Christoph

2007-01-01

Objective Intra‐articularly applied opioid agonists or antagonists modulate pain after knee surgery and in chronic arthritis. Therefore, the expression of β‐endorphin (END), Met‐enkephalin (ENK), and μ and δ opioid receptors (ORs) within synovium of patients with joint trauma (JT), osteoarthritis (OA) and rheumatoid arthritis (RA) were examined. Methods Synovial samples were subjected to double immunohistochemical analysis of opioid peptides with immune cell markers, and of ORs with the neuronal markers calcitonin gene‐related peptide (CGRP) and tyrosine hydroxylase (TH). Results END and ENK were expressed by macrophage‐like (CD68+) and fibroblast‐like (CD68−) cells within synovial lining layers of all disorders. In the sublining layers, END and ENK were mostly expressed by granulocytes in patients with JT, and by macrophages/monocytes, lymphocytes and plasma cells in those with OA and RA. Overall, END‐ and ENK‐immunoreactive (IR) cells were more abundant in patients with RA than in those with OA and JT. ORs were found on nerve fibres and immune cells in all patients. OR‐IR nerve fibres were significantly more abundant in patients with RA than in those with OA and JT. μORs and δORs were coexpressed with CGRP but not with TH. Conclusions Parallel to the severity of inflammation, END and ENK in immune cells and their receptors on sensory nerve terminals are more abundant in patients with RA than in those with JT and OA. These findings are consistent with the notion that, with prolonged and enhanced inflammation, the immune and peripheral nervous systems upregulate sensory nerves expressing ORs and their ligands to counterbalance pain and inflammation. PMID:17324971

Inversion layer solar cell fabrication and evaluation. [etching on silicon films

NASA Technical Reports Server (NTRS)

Call, R. L.

1974-01-01

Inversion layer solar cells were fabricated by etching through the diffused layer on p-type silicon wafers in a comb-like contact pattern. The charge separation comes from an induced p-n junction at the surface. The inverted surface is caused by a layer of transparent material applied to the surface that either contains free positive ions or that creates donor states at the interface. Cells are increased from 3 ma I sub sc to 100 ma by application of sodium silicate. The action is unstable, however, and decays. Non-mesa contaminated oxide cells were fabricated with short circuit currents of over 100 ma measured in the sun. Cells of this type have demonstrated stability.

The entorhinal cortex of the Megachiroptera: a comparative study of Wahlberg's epauletted fruit bat and the straw-coloured fruit bat.

PubMed

Gatome, Catherine W; Slomianka, Lutz; Mwangi, Dieter K; Lipp, Hans-Peter; Amrein, Irmgard

2010-05-01

This study describes the organisation of the entorhinal cortex of the Megachiroptera, straw-coloured fruit bat and Wahlberg's epauletted fruit bat. Using Nissl and Timm stains, parvalbumin and SMI-32 immunohistochemistry, we identified five fields within the medial (MEA) and lateral (LEA) entorhinal areas. MEA fields E(CL) and E(C) are characterised by a poor differentiation between layers II and III, a distinct layer IV and broad, stratified layers V and VI. LEA fields E(I), E(R) and E(L) are distinguished by cell clusters in layer II, a clear differentiation between layers II and III, a wide columnar layer III and a broad sublayer Va. Clustering in LEA layer II was more typical of the straw-coloured fruit bat. Timm-staining was most intense in layers Ib and II across all fields and layer III of field E(R). Parvalbumin-like staining varied along a medio-lateral gradient with highest immunoreactivity in layers II and III of MEA and more lateral fields of LEA. Sparse SMI-32-like immunoreactivity was seen only in Wahlberg's epauletted fruit bat. Of the neurons in MEA layer II, ovoid stellate cells account for approximately 38%, polygonal stellate cells for approximately 8%, pyramidal cells for approximately 18%, oblique pyramidal cells for approximately 6% and other neurons of variable morphology for approximately 29%. Differences between bats and other species in cellular make-up and cytoarchitecture of layer II may relate to their three-dimensional habitat. Cytoarchitecture of layer V in conjunction with high encephalisation and structural changes in the hippocampus suggest similarities in efferent hippocampal --> entorhinal --> cortical interactions between fruit bats and primates.

Voc enhancement of a solar cell with doped Li+-PbS as the active layer

NASA Astrophysics Data System (ADS)

Chávez Portillo, M.; Alvarado Pulido, J.; Gallardo Hernández, S.; Soto Cruz, B. S.; Alcántara Iniesta, S.; Gutiérrez Pérez, R.; Portillo Moreno, O.

2018-06-01

In this report, we investigate the fabrication of solar cells obtained by chemical bath technique, based on CdS as window layer and PbS and PbS-Li+-doped as the active layer. We report open-circuit-voltage Voc values of ∼392 meV for PbS and ∼630 meV for PbSLi+-doped, a remarkable enhanced in the open circuit voltage is shown for solar cells with doped active layer. Li+ ion passivate the dangling bonds in PbS-metal layer interface in consequence reducing the recombination centers.

Improved and targeted delivery of bioactive molecules to cells with magnetic layer-by-layer assembled microcapsules

NASA Astrophysics Data System (ADS)

Pavlov, Anton M.; Gabriel, Samantha A.; Sukhorukov, Gleb B.; Gould, David J.

2015-05-01

Despite our increasing knowledge of cell biology and the recognition of an increasing repertoire of druggable intracellular therapeutic targets, there remain a limited number of approaches to deliver bioactive molecules to cells and even fewer that enable targeted delivery. Layer-by-layer (LbL) microcapsules are assembled using alternate layers of oppositely charged molecules and are potential cell delivery vehicles for applications in nanomedicine. There are a wide variety of charged molecules that can be included in the microcapsule structure including metal nanoparticles that introduce physical attributes. Delivery of bioactive molecules to cells with LbL microcapsules has recently been demonstrated, so in this study we explore the delivery of bioactive molecules (luciferase enzyme and plasmid DNA) to cells using biodegradable microcapsules containing a layer of magnetite nanoparticles. Interestingly, significantly improved intracellular luciferase enzyme activity (25 fold) and increased transfection efficiency with plasmid DNA (3.4 fold) was observed with magnetic microcapsules. The use of a neodymium magnet enabled efficient targeting of magnetic microcapsules which further improved the delivery efficiency of the cargoes as a consequence of increased microcapsule concentration at the magnetic site. Microcapsules were well tolerated by cells in these experiments and only displayed signs of toxicity at a capsule : cell ratio of 100 : 1 and with extended exposure. These studies illustrate how multi-functionalization of LbL microcapsules can improve and target delivery of bioactive molecules to cells.

Fuel cell cassette with compliant seal

DOEpatents

Karl, Haltiner, Jr. J.; Anthony, Derose J.; Klotzbach, Darasack C.; Schneider, Jonathan R.

2017-11-07

A fuel cell cassette for forming a fuel cell stack along a fuel cell axis includes a cell retainer, a plate positioned axially to the cell retainer and defining a space axially with the cell retainer, and a fuel cell having an anode layer and a cathode layer separated by an electrolyte layer. The outer perimeter of the fuel cell is positioned in the space between the plate and the cell retainer, thereby retaining the fuel cell and defining a cavity between the cell retainer, the fuel cell, and the plate. The fuel cell cassette also includes a seal disposed within the cavity for sealing the edge of the fuel cell. The seal is compliant at operational temperatures of the fuel cell, thereby allowing lateral expansion and contraction of the fuel cell within the cavity while maintaining sealing at the edge of the fuel cell.

IUS materials outgassing condensation effects on sensitive spacecraft surfaces

NASA Technical Reports Server (NTRS)

Mullen, C. R.; Shaw, C. G.; Crutcher, E. R.

1982-01-01

Four materials used on the inertial upper state (IUS) were subjected to vacuum conditions and heated to near-operational temperatures (93 to 316 C), releasing volatile materials. A fraction of the volatile materials were collected on 25 C solar cells, optical solar reflectors (OSR's) or aluminized Mylar. The contaminated surfaces were exposed to 26 equivalent sun hours of simulated solar ultraviolet (UV) radiation. Measurements of contamination deposit mass, structure, reflectance and effects on solar cell power output were made before and after UV irradiation. Standard total mass loss - volatile condensible materials (TML - VCM) tests were also performed. A 2500 A thick contaminant layer produced by EPDM rubber motor-case insulation outgassing increased the solar absorptance of the OSR's from 0.07 to 0.14, and to 0.18 after UV exposure. An 83,000 A layer caused an increase from 0.07 to 0.21, and then the 0.46 after UV exposure. The Kevlar-epoxy motor-case material outgassing condensation raised the absorptance from 0.07 to 0.13, but UV had no effect. Outgassing from multilayer insulation and carbon-carbon nozzle materials did not affect the solar absorptance of the OSR's.

"Subpial Fan Cell" - A Class of Calretinin Neuron in Layer 1 of Adult Monkey Prefrontal Cortex.

PubMed

Gabbott, Paul L A

2016-01-01

Layer 1 of the cortex contains populations of neurochemically distinct neurons and afferent fibers which markedly affect neural activity in the apical dendritic tufts of pyramidal cells. Understanding the causal mechanisms requires knowledge of the cellular architecture and synaptic organization of layer 1. This study has identified eight morphological classes of calretinin immunopositive (CRet+) neurons (including Cajal-Retzius cells) in layer 1 of the prefrontal cortex (PFC) in adult monkey (Macaca fasicularis), with a distinct class - termed "subpial fan (SPF) cell" - described in detail. SPF cells were rare horizontal unipolar CRet+ cells located directly beneath the pia with a single thick primary dendrite that branched into a characteristic fan-like dendritic tree tangential to the pial surface. Dendrites had spines, filamentous processes and thorny branchlets. SPF cells lay millimeters apart with intralaminar axons that ramified widely in upper layer 1. Such cells were GABA immunonegative (-) and occurred in areas beyond PFC. Interspersed amidst SPF cells displaying normal structural integrity were degenerating CRet+ neurons (including SPF cells) and clumps of lipofuscin-rich cellular debris. The number of degenerating SPF cells increased during adulthood. Ultrastructural analyses indicated SPF cell somata received asymmetric (A - presumed excitatory) and symmetric (S - presumed inhibitory) synaptic contacts. Proximal dendritic shafts received mainly S-type and distal shafts mostly A-type input. All dendritic thorns and most dendritic spines received both synapse types. The tangential areal density of SPF cell axonal varicosities varied radially from parent somata - with dense clusters in more distal zones. All boutons formed A-type contacts with CRet- structures. The main post-synaptic targets were dendritic shafts (67%; mostly spine-bearing) and dendritic spines (24%). SPF-SPF cell innervation was not observed. Morphometry of SPF cells indicated a unique class of CRet+/GABA- neuron in adult monkey PFC - possibly a subtype of persisting Cajal-Retzius cell. The distribution and connectivity of SPF cells suggest they act as integrative hubs in upper layer 1 during postnatal maturation. The main synaptic output of SPF cells likely provides a transminicolumnar excitatory influence across swathes of apical dendritic tufts - thus affecting information processing in discrete patches of layer 1 in adult monkey PFC.

Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells.

PubMed

Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

2014-10-01

Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se 2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF 2 coated with a thin atomic layer deposited Al 2 O 3 layer, or direct current magnetron sputtering of Al 2 O 3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al 2 O 3 /CIGS rear interface. (MgF 2 /)Al 2 O 3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells.

Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells

PubMed Central

Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

2014-01-01

Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF2 coated with a thin atomic layer deposited Al2O3 layer, or direct current magnetron sputtering of Al2O3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al2O3/CIGS rear interface. (MgF2/)Al2O3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells. PMID:26300619

Optical Coherence Tomography (OCT) Device Independent Intraretinal Layer Segmentation

PubMed Central

Ehnes, Alexander; Wenner, Yaroslava; Friedburg, Christoph; Preising, Markus N.; Bowl, Wadim; Sekundo, Walter; zu Bexten, Erdmuthe Meyer; Stieger, Knut; Lorenz, Birgit

2014-01-01

Purpose To develop and test an algorithm to segment intraretinal layers irrespectively of the actual Optical Coherence Tomography (OCT) device used. Methods The developed algorithm is based on the graph theory optimization. The algorithm's performance was evaluated against that of three expert graders for unsigned boundary position difference and thickness measurement of a retinal layer group in 50 and 41 B-scans, respectively. Reproducibility of the algorithm was tested in 30 C-scans of 10 healthy subjects each with the Spectralis and the Stratus OCT. Comparability between different devices was evaluated in 84 C-scans (volume or radial scans) obtained from 21 healthy subjects, two scans per subject with the Spectralis OCT, and one scan per subject each with the Stratus OCT and the RTVue-100 OCT. Each C-scan was segmented and the mean thickness for each retinal layer in sections of the early treatment of diabetic retinopathy study (ETDRS) grid was measured. Results The algorithm was able to segment up to 11 intraretinal layers. Measurements with the algorithm were within the 95% confidence interval of a single grader and the difference was smaller than the interindividual difference between the expert graders themselves. The cross-device examination of ETDRS-grid related layer thicknesses highly agreed between the three OCT devices. The algorithm correctly segmented a C-scan of a patient with X-linked retinitis pigmentosa. Conclusions The segmentation software provides device-independent, reliable, and reproducible analysis of intraretinal layers, similar to what is obtained from expert graders. Translational Relevance Potential application of the software includes routine clinical practice and multicenter clinical trials. PMID:24820053

Solar cells and methods of fabrication thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shumate, Seth Daniel; Hutchings, Douglas Arthur; Mohammed, Hafeezuddin

A passivation layer is deposited on a first portion of a region of the solar cell. A grid line is deposited on a second portion of the region. The passivation layer is annealed to drive chemical species from the passivation layer to deactivate an electrical activity of a dopant in the first portion of the region of the solar cell.

C-reactive protein induces matrix metalloproteinase-1 and -10 in human endothelial cells: implications for clinical and subclinical atherosclerosis.

PubMed

Montero, Ines; Orbe, Josune; Varo, Nerea; Beloqui, Oscar; Monreal, José I; Rodríguez, José A; Díez, Javier; Libby, Peter; Páramo, José A

2006-04-04

We examined the effect of C-reactive protein (CRP) on matrix metalloproteinase (MMP) and inhibitor expression in endothelial cells and in patients with clinical and subclinical atherosclerosis. In addition to predicting atherosclerotic vascular disease, CRP may directly promote a proinflammatory/proatherosclerotic phenotype. Human umbilical vein endothelial cells (HUVECs) and aortic endothelial cells (HAECs) were incubated in the presence or absence of CRP (50 mug/ml). Microarray analysis, real-time polymerase chain reaction, immunological and activity assays for MMPs were performed. Specific inhibitors of mitogen-activated protein kinase pathway were used. The MMP-1 and -10 plasma levels were measured in apparently healthy subjects (n = 70). Immunolocalization of CRP, MMP-1, and MMP-10 was performed in human mammary arteries and carotid endarterectomy specimens. C-reactive protein augmented MMP-1 and -10 messenger ribonucleic acid expression in HUVEC (p < 0.05) and HAEC (p < 0.01). C-reactive protein stimulation also increased MMP-1 and -10 protein in conditioned culture medium (p < 0.001), as well as MMP activity (p = 0.001). Specific inhibition of p38 or MEK abolished the CRP induction of the MMP-1, whereas MMP-10 induction blockade required the simultaneous inhibition of p38 and Jun N-terminal kinase pathways. Subjects with CRP values >3 mg/l (n = 37) had increased plasma MMP-1 and -10 (p < 0.05), the association being significant after adjustment for confounding variables (p = 0.04 and p = 0.008, respectively). The MMP-10 levels were elevated in subjects with higher carotid intima-media thickness (p = 0.009). Increased CRP and MMP-10 colocalized in endothelial layer and macrophage-rich areas in advanced atherosclerotic plaques. Increased local and systemic CRP-related MMP activation might provide a link between inflammation and plaque vulnerability.

Advances in Plexcore active layer technology systems for organic photovoltaics: roof-top and accelerated lifetime analysis of high performance organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Laird, Darin W.; Vaidya, Swanand; Li, Sergey; Mathai, Mathew; Woodworth, Brian; Sheina, Elena; Williams, Shawn; Hammond, Troy

2007-09-01

We report NREL-certified efficiencies and initial lifetime data for organic photovoltaic (OPV) cells based on Plexcore PV photoactive layer and Plexcore HTL-OPV hole transport layer technology. Plexcore PV-F3, a photoactive layer OPV ink, was certified in a single-layer OPV cell at the National Renewable Energy Laboratory (NREL) at 5.4%, which represents the highest official mark for a single-layer organic solar cell. We have fabricated and measured P3HT:PCBM solar cells with a peak efficiency of 4.4% and typical efficiencies of 3 - 4% (internal, NREL-calibrated measurement) with P3HT manufactured at Plextronics by the Grignard Metathesis (GRIM) method. Outdoor and accelerated lifetime testing of these devices is reported. Both Plexcore PV-F3 and P3HT:PCBM-based OPV cells exhibit >750 hours of outdoor roof-top, non-accelerated lifetime with less than 8% loss in initial efficiency for both active layer systems when exposed continuously to the climate of Western Pennsylvania. These devices are continuously being tested to date. Accelerated testing using a high-intensity (1000W) metal-halide lamp affords shorter lifetimes; however, the true acceleration factor is still to be determined.

Efficient methylammonium lead iodide perovskite solar cells with active layers from 300 to 900 nm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Momblona, C.; Malinkiewicz, O.; Soriano, A.

2014-08-01

Efficient methylammonium lead iodide perovskite-based solar cells have been prepared in which the perovskite layer is sandwiched in between two organic charge transporting layers that block holes and electrons, respectively. This configuration leads to stable and reproducible devices that do not suffer from strong hysteresis effects and when optimized lead to efficiencies close to 15%. The perovskite layer is formed by using a dual-source thermal evaporation method, whereas the organic layers are processed from solution. The dual-source thermal evaporation method leads to smooth films and allows for high precision thickness variations. Devices were prepared with perovskite layer thicknesses ranging frommore » 160 to 900 nm. The short-circuit current observed for these devices increased with increasing perovskite layer thickness. The main parameter that decreases with increasing perovskite layer thickness is the fill factor and as a result optimum device performance is obtained for perovskite layer thickness around 300 nm. However, here we demonstrate that with a slightly oxidized electron blocking layer the fill factor for the solar cells with a perovskite layer thickness of 900 nm increases to the same values as for the devices with thin perovskite layers. As a result the power conversion efficiencies for the cells with 300 and 900 nm are very similar, 12.7% and 12%, respectively.« less

The catalyst layer and its dimensionality - A look into its ingredients and how to characterize their effects

NASA Astrophysics Data System (ADS)

Zamel, Nada

2016-03-01

Development of polymer electrolyte membrane (PEM) fuel cells throughout the years is established through its component optimization. This is especially true of its catalyst layer, where structuring of the layer has led to many breakthroughs. The catalyst layer acts as the heart of the cell, where it controls the half-cell reactions and their products. The complex nature of various transport phenomena simultaneously taking place in the layer requires the layer to be heterogeneous in structure. Hence, a delicate balance of the layer's ingredients, coupled with the understanding of the ingredients' interaction, is required. State-of-the-art catalyst layers are composed of a catalyst, its support, a solvent and a binder. Changes in the morphology, structure or material of any of these components ultimately affects the layer's activity and durability. In this review paper, we provide an overview of the various works tailored to understand how each component in the catalyst's ink affects the stability and life-time of the layer.

Fabricating amorphous silicon solar cells by varying the temperature _of the substrate during deposition of the amorphous silicon layer

DOEpatents

Carlson, David E.

1982-01-01

An improved process for fabricating amorphous silicon solar cells in which the temperature of the substrate is varied during the deposition of the amorphous silicon layer is described. Solar cells manufactured in accordance with this process are shown to have increased efficiencies and fill factors when compared to solar cells manufactured with a constant substrate temperature during deposition of the amorphous silicon layer.

Immunocytochemical localization of calretinin containing neurons in retina from rabbit, cat, and dog.

PubMed

Jeon, M H; Jeon, C J

1998-09-01

Calcium homeostasis is critical for many neuronal functions, yet the distribution of calcium-binding protein is not always conserved among species, even between closely related species. We decided therefore to study the distribution of one of these calcium-binding proteins calretinin, in retina from rabbit, cat, and dog. Calretinin was localized using antibody immunocytochemistry. Calretinin immunoreactivity was found in numerous cell bodies in the ganglion cell layer in all three animals. These cells had small to medium-sized somas. Large ganglion cells, however, were not labeled using antiserum against calretinin. In the inner nuclear layer, calretinin immunoreactivity was found in many neurons in all three species. The regular distribution of neurons, the inner marginal location of their cell bodies in the inner nuclear layer, and the distinctive bilaminar morphologies of their dendritic arbors in the inner plexiform layer suggested that these calretinin-positive cells were AII amacrine cells. Calretinin immunoreactivity was observed in both A- and B-type horizontal cells in cat and dog retina. However, horizontal cells in the rabbit retina were not labeled by this antibody. Neurons in the photoreceptor cell layer were not labeled by this antibody. The present study suggests that calretinin immunoreactivity is present in several populations in the retina. In particular, calretinin labels AII amacrine cells and a subpopulation of ganglion cells in all three animals. Horizontal cells, however, were not labeled in rabbit.

Endomembrane proteomics reveals putative enzymes involved in cell wall metabolism in wheat grain outer layers

PubMed Central

Chateigner-Boutin, Anne-Laure; Suliman, Muhtadi; Bouchet, Brigitte; Alvarado, Camille; Lollier, Virginie; Rogniaux, Hélène; Guillon, Fabienne; Larré, Colette

2015-01-01

Cereal grain outer layers fulfil essential functions for the developing seed such as supplying energy and providing protection. In the food industry, the grain outer layers called ‘the bran’ is valuable since it is rich in dietary fibre and other beneficial nutriments. The outer layers comprise several tissues with a high content in cell wall material. The cell wall composition of the grain peripheral tissues was investigated with specific probes at a stage of active cell wall synthesis. Considerable wall diversity between cell types was revealed. To identify the cellular machinery involved in cell wall synthesis, a subcellular proteomic approach was used targeting the Golgi apparatus where most cell wall polysaccharides are synthesized. The tissues were dissected into outer pericarp and intermediate layers where 822 and 1304 proteins were identified respectively. Many carbohydrate-active enzymes were revealed: some in the two peripheral grain fractions, others only in one tissue. Several protein families specific to one fraction and with characterized homologs in other species might be related to the specific detection of a polysaccharide in a particular cell layer. This report provides new information on grain cell walls and its biosynthesis in the valuable outer tissues, which are poorly studied so far. A better understanding of the mechanisms controlling cell wall composition could help to improve several quality traits of cereal products (e.g. dietary fibre content, biomass conversion to biofuel). PMID:25769308

Fabrication of contacts for silicon solar cells including printing burn through layers

DOEpatents

Ginley, David S; Kaydanova, Tatiana; Miedaner, Alexander; Curtis, Calvin J; Van Hest, Marinus Franciscus Antonius Maria

2014-06-24

A method for fabricating a contact (240) for a solar cell (200). The method includes providing a solar cell substrate (210) with a surface that is covered or includes an antireflective coating (220). For example, the substrate (210) may be positioned adjacent or proximate to an outlet of an inkjet printer (712) or other deposition device. The method continues with forming a burn through layer (230) on the coating (220) by depositing a metal oxide precursor (e.g., using an inkjet or other non-contact printing method to print or apply a volume of liquid or solution containing the precursor). The method includes forming a contact layer (240) comprising silver over or on the burn through layer (230), and then annealing is performed to electrically connect the contact layer (240) to the surface of the solar cell substrate (210) through a portion of the burn through layer (230) and the coating (220).

Thin-film solar cell fabricated on a flexible metallic substrate

DOEpatents

Tuttle, John R.; Noufi, Rommel; Hasoon, Falah S.

2006-05-30

A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

PubMed

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-18

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

Thin-Film Solar Cell Fabricated on a Flexible Metallic Substrate

DOEpatents

Tuttle, J. R.; Noufi, R.; Hasoon, F. S.

2006-05-30

A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

NASA Astrophysics Data System (ADS)

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-01

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

Epitaxial solar cells fabrication

NASA Technical Reports Server (NTRS)

Daiello, R. V.; Robinson, P. H.; Kressel, H.

1975-01-01

Silicon epitaxy has been studied for the fabrication of solar cell structures, with the intent of optimizing efficiency while maintaining suitability for space applications. SiH2CL2 yielded good quality layers and junctions with reproducible impurity profiles. Diode characteristics and lifetimes in the epitaxial layers were investigated as a function of epitaxial growth conditions and doping profile, as was the effect of substrates and epitaxial post-gettering on lifetime. The pyrolytic decomposition of SiH4 was also used in the epitaxial formation of highly doped junction layers on bulk Si wafers. The effects of junction layer thickness and bulk background doping level on cell performance, in particular, open-circuit voltage, were investigated. The most successful solar cells were fabricated with SiH2 CL2 to grow p/n layers on n(+) substrates. The best performance was obtained from a p(+)/p/n/n(+) structure grown with an exponential grade in the n-base layer.

Effect of TiO 2 particle size and layer thickness on mesoscopic perovskite solar cells

DOE PAGES

Lee, Dong Geon; Kim, Min-cheol; Kim, Byeong Jo; ...

2017-11-16

Mesoporous TiO 2 (mp-TiO 2) layers are commonly used as electron transport layers in perovskite solar cells, which help to extract electrons from the perovskite light-absorbing layer and transport them to the electrodes. We investigated the effects of the layer thickness of mp-TiO 2 and particle size of TiO 2 on photovoltaic properties, in terms of the surface area of the mp-layer and the interfacial areas of the TiO 2 nanoparticles in the mp-layer. Various mp-TiO 2 layers with thicknesses of 150, 250, and 400 nm and particle sizes of 25 nm and 41 nm were prepared to compare themore » photovoltaic properties of such layer-containing perovskite solar cells. Time-resolved photoluminescence decay and impedance studies showed that interfacial resistance as well as perovskite-to-TiO 2 charge injection are important factors affecting photovoltaic performance. The deterioration of the photovoltaic parameters with increasing TiO 2/TiO 2 interfacial area also confirms that the interfacial series resistance that arises from these connections should be reduced to enhance the performance of mesoscopic perovskite solar cells.« less

Effect of TiO 2 particle size and layer thickness on mesoscopic perovskite solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Dong Geon; Kim, Min-cheol; Kim, Byeong Jo

Mesoporous TiO 2 (mp-TiO 2) layers are commonly used as electron transport layers in perovskite solar cells, which help to extract electrons from the perovskite light-absorbing layer and transport them to the electrodes. We investigated the effects of the layer thickness of mp-TiO 2 and particle size of TiO 2 on photovoltaic properties, in terms of the surface area of the mp-layer and the interfacial areas of the TiO 2 nanoparticles in the mp-layer. Various mp-TiO 2 layers with thicknesses of 150, 250, and 400 nm and particle sizes of 25 nm and 41 nm were prepared to compare themore » photovoltaic properties of such layer-containing perovskite solar cells. Time-resolved photoluminescence decay and impedance studies showed that interfacial resistance as well as perovskite-to-TiO 2 charge injection are important factors affecting photovoltaic performance. The deterioration of the photovoltaic parameters with increasing TiO 2/TiO 2 interfacial area also confirms that the interfacial series resistance that arises from these connections should be reduced to enhance the performance of mesoscopic perovskite solar cells.« less

Generating Inviscid and Viscous Fluid-Flow Simulations over an Aircraft Surface Using a Fluid-Flow Mesh

NASA Technical Reports Server (NTRS)

Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)

2013-01-01

Fluid-flow simulation over a computer-generated aircraft surface is generated using inviscid and viscous simulations. A fluid-flow mesh of fluid cells is obtained. At least one inviscid fluid property for the fluid cells is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. A set of intersecting fluid cells that intersects the aircraft surface are identified. One surface mesh polygon of the surface mesh is identified for each intersecting fluid cell. A boundary-layer prediction point for each identified surface mesh polygon is determined. At least one boundary-layer fluid property for each boundary-layer prediction point is determined using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects. At least one updated fluid property for at least one fluid cell is determined using the at least one boundary-layer fluid property and the inviscid fluid simulation.

Room-Temperature Processing of TiOx Electron Transporting Layer for Perovskite Solar Cells.

PubMed

Deng, Xiaoyu; Wilkes, George C; Chen, Alexander Z; Prasad, Narasimha S; Gupta, Mool C; Choi, Joshua J

2017-07-20

In order to realize high-throughput roll-to-roll manufacturing of flexible perovskite solar cells, low-temperature processing of all device components must be realized. However, the most commonly used electron transporting layer in high-performance perovskite solar cells is based on TiO 2 thin films processed at high temperature (>450 °C). Here, we demonstrate room temperature solution processing of the TiO x layer that performs as well as the high temperature TiO 2 layer in perovskite solar cells, as evidenced by a champion solar cell efficiency of 16.3%. Using optical spectroscopy, electrical measurements, and X-ray diffraction, we show that the room-temperature processed TiO x is amorphous with organic residues, and yet its optical and electrical properties are on par with the high-temperature TiO 2 . Flexible perovskite solar cells that employ a room-temperature TiO x layer with a power conversion efficiency of 14.3% are demonstrated.

Wide-angle light-trapping electrode for photovoltaic cells.

PubMed

Omelyanovich, Mikhail M; Simovski, Constantin R

2017-10-01

In this Letter, we experimentally show that a submicron layer of a transparent conducting oxide that may serve a top electrode of a photovoltaic cell based on amorphous silicon when properly patterned by notches becomes an efficient light-trapping structure. This is so for amorphous silicon thin-film solar cells with properly chosen thicknesses of the active layers (p-i-n structure with optimal thicknesses of intrinsic and doped layers). The nanopatterned layer of transparent conducting oxide reduces both the light reflectance from the photovoltaic cell and transmittance through the photovoltaic layers for normal incidence and for all incidence angles. We explain the physical mechanism of our light-trapping effect, prove that this mechanism is realized in our structure, and show that the nanopatterning is achievable in a rather easy and affordable way that makes our method of solar cell enhancement attractive for industrial adaptations.

Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman, E-mail: anis@eee.buet.ac.bd

2016-05-21

Although ultra-thin-film solar cells can be attractive in reducing the cost, they suffer from low absorption as the thickness of the active layer is usually much smaller than the wavelength of incident light. Different nano-photonic techniques, including plasmonic structures, are being explored to increase the light absorption in ultra-thin-film solar cells. More than one layer of active materials with different energy bandgaps can be used in tandem to increase the light absorption as well. However, due to different amount of light absorption in different active layers, photo-generated currents in different active layers will not be the same. The current mismatchmore » between the tandem layers makes them ineffective in increasing the efficiency. In this work, we investigate the light absorption properties of tandem solar cells with two ultra-thin active layers working as two subcells and a metal layer with periodically perforated holes in-between the two subcells. While the metal layer helps to overcome the current mismatch, the periodic holes increase the absorption of incident light by helping extraordinary optical transmission of the incident light from the top to the bottom subcell, and by coupling the incident light to plasmonic and photonic modes within ultra-thin active layers. We extensively study the effects of the geometry of holes in the intermediate metal layer on the light absorption properties of tandem solar cells with ultra-thin active layers. We also study how different metals in the intermediate layer affect the light absorption; how the geometry of holes in the intermediate layer affects the absorption when the active layer materials are changed; and how the intermediate metal layer affects the collection of photo-generated electron-hole pairs at the terminals. We find that in a solar cell with 6,6-phenyl C61-butyric acid methyl ester top subcell and copper indium gallium selenide bottom subcell, if the periodic holes in the metal layer are square or polygon, total absorption remains approximately the same. However, the total absorption suffers significantly if the holes are triangle. The transmission spectra of incident light into the bottom subcell, and hence the absorption, change significantly for square and circle holes if the active materials change to cadmium selenide (CdSe) and cadmium telluride (CdTe) in the top and bottom subcells, respectively. Although the intermediate metal layer may induce electron-hole pair recombination due to surface defects, the short-circuit current density of an ultra-thin plasmonic solar cell with an intermediate metal layer with two-dimensional hole array is >9% of that of a structure without the intermediate metal layer.« less

Single-unit-cell layer established Bi 2 WO 6 3D hierarchical architectures: Efficient adsorption, photocatalysis and dye-sensitized photoelectrochemical performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Hongwei; Cao, Ranran; Yu, Shixin

Single-layer catalysis sparks huge interests and gains widespread attention owing to its high activity. Simultaneously, three-dimensional (3D) hierarchical structure can afford large surface area and abundant reactive sites, contributing to high efficiency. Herein, we report an absorbing single-unit-cell layer established Bi2WO6 3D hierarchical architecture fabricated by a sodium dodecyl benzene sulfonate (SDBS)-assisted assembled strategy. The DBS- long chains can adsorb on the (Bi2O2)2+ layers and hence impede stacking of the layers, resulting in the single-unit-cell layer. We also uncovered that SDS with a shorter chain is less effective than SDBS. Due to the sufficient exposure of surface O atoms, single-unit-cellmore » layer 3D Bi2WO6 shows strong selectivity for adsorption on multiform organic dyes with different charges. Remarkably, the single-unit-cell layer 3D Bi2WO6 casts profoundly enhanced photodegradation activity and especially a superior photocatalytic H2 evolution rate, which is 14-fold increase in contrast to the bulk Bi2WO6. Systematic photoelectrochemical characterizations disclose that the substantially elevated carrier density and charge separation efficiency take responsibility for the strengthened photocatalytic performance. Additionally, the possibility of single-unit-cell layer 3D Bi2WO6 as dye-sensitized solar cells (DSSC) has also been attempted and it was manifested to be a promising dye-sensitized photoanode for oxygen evolution reaction (ORR). Our work not only furnish an insight into designing single-layer assembled 3D hierarchical architecture, but also offer a multi-functional material for environmental and energy applications.« less

Microstructures of tribologically modified surface layers in two-phase alloys

NASA Astrophysics Data System (ADS)

Figueroa, C. G.; Ortega, I.; Jacobo, V. H.; Ortiz, A.; Bravo, A. E.; Schouwenaars, R.

2014-08-01

When ductile alloys are subject to sliding wear, small increments of plastic strain accumulate into severe plastic deformation and mechanical alloying of the surface layer. The authors constructed a simple coaxial tribometer, which was used to study this phenomenon in wrought Al-Sn and cast Cu-Mg-Sn alloys. The first class of materials is ductile and consists of two immiscible phases. Tribological modification is observed in the form of a transition zone from virgin material to severely deformed grains. At the surface, mechanical mixing of both phases competes with diffusional unmixing. Vortex flow patterns are typically observed. The experimental Cu-Mg-Sn alloys are ductile for Mg-contents up to 2 wt% and consist of a- dendrites with a eutectic consisting of a brittle Cu2Mg-matrix with α-particles. In these, the observations are similar to the Al-Sn Alloys. Alloys with 5 wt% Mg are brittle due to the contiguity of the eutectic compound. Nonetheless, under sliding contact, this compound behaves in a ductile manner, showing mechanical mixing of a and Cu2Mg in the top layers and a remarkable transition from a eutectic to cellular microstructure just below, due to severe shear deformation. AFM-observations allow identifying the mechanically homogenized surface layers as a nanocrystalline material with a cell structure associated to the sliding direction.

Selenium Interlayer for High-Efficiency Multijunction Solar Cell

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A (Inventor)

2015-01-01

A multi junction solar cell is provided and includes multiple semiconducting layers and an interface layer disposed between the multiple semiconducting layers. The interface layer is made from an interface bonding material that has a refractive index such that a ratio of a refractive index of each of the multiple semiconducting layers to the refractive index of the interface bonding material is less than or equal to 1.5.

Selenium Interlayer for High-Efficiency Multijunction Solar Cell

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A. (Inventor)

2016-01-01

A multi-junction solar cell is provided and includes multiple semiconducting layers and an interface layer disposed between the multiple semiconducting layers. The interface layer is made from an interface bonding material that has a refractive index such that a ratio of a refractive index of each of the multiple semiconducting layers to the refractive index of the interface bonding material is less than or equal to 1.5.

Thin film solar cells by selenization sulfurization using diethyl selenium as a selenium precursor

DOEpatents

Dhere, Neelkanth G.; Kadam, Ankur A.

2009-12-15

A method of forming a CIGSS absorber layer includes the steps of providing a metal precursor, and selenizing the metal precursor using diethyl selenium to form a selenized metal precursor layer (CIGSS absorber layer). A high efficiency solar cell includes a CIGSS absorber layer formed by a process including selenizing a metal precursor using diethyl selenium to form the CIGSS absorber layer.

ELECTRON MICROSCOPE STUDY OF MYCOBACTERIUM LEPRAE AND ITS ENVIRONMENT IN A VESICULAR LEPROUS LESION

PubMed Central

Imaeda, Tamotsu; Convit, Jacinto

1962-01-01

Imaeda, Tamotsu (Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela) and Jacinto Convit. Electron microscope study of Mycobacterium leprae and its environment in a vesicular leprous lesion. J. Bacteriol. 83:43–52. 1962.—Biopsied specimens of a borderline leprosy lesion were observed with the electron microscope. In this lesion, the majority of Mycobacterium leprae were laden with cytoplasmic components. The bacilli were separated from the cytoplasm of host cells by an enclosing membrane, thus differing from the environment of well-developed lepra cells in lepromatous lesions. The cell wall is composed of a moderately dense layer. A diffuse layer is discernible outside the cell wall, separated from it by a low density space. It is suggested that the cell wall is further coated by a low density layer, although the nature of the outermost diffuse layer has not yet been determined. The plasma membrane consists of a double layer, i.e., dense inner and outer layers separated by a low density space. The outer layer is closely adjacent to the cell wall. In the region where the outer layer of the plasma membrane enters the cytoplasm and is transformed into a complex membranous structure, the inner layer encloses this membranous configuration. Together they form the intracytoplasmic membrane system. In the bacterial cytoplasm, moderately dense, presumably polyphosphate bodies are apparent. As neither these bodies nor the intracytoplasmic membrane system are visible in the degenerating bacilli, it seems probable that these two components represent indicators of the state of bacillary activity. Images PMID:16561926

Model for the ultrasound reflection from micro-beads and cells distributed in layers on a uniform surface

NASA Astrophysics Data System (ADS)

Couture, O.; Cherin, E.; Foster, F. S.

2007-07-01

A model predicting the reflection of ultrasound from multiple layers of small scattering spheres is developed. Predictions of the reflection coefficient, which takes into account the interferences between the different sphere layers, are compared to measurements performed in the 10-80 MHz and 15-35 MHz frequency range with layers of glass beads and spherical acute myeloid leukemia (AML) cells, respectively. For both types of scatterers, the reflection coefficient increases as a function of their density on the surface for less than three superimposed layers, at which point it saturates at 0.38 for glass beads and 0.02 for AML cells. Above three layers, oscillations of the reflection coefficient due to constructive or destructive interference between layers are observed experimentally and are accurately predicted by the model. The use of such a model could lead to a better understanding of the structures observed in layered tissue images.

Cell Class-Dependent Intracortical Connectivity and Output Dynamics of Layer 6 Projection Neurons of the Rat Primary Visual Cortex.

PubMed

Cotel, Florence; Fletcher, Lee N; Kalita-de Croft, Simon; Apergis-Schoute, John; Williams, Stephen R

2018-07-01

Neocortical information processing is powerfully influenced by the activity of layer 6 projection neurons through control of local intracortical and subcortical circuitry. Morphologically distinct classes of layer 6 projection neuron have been identified in the mammalian visual cortex, which exhibit contrasting receptive field properties, but little information is available on their functional specificity. To address this we combined anatomical tracing techniques with high-resolution patch-clamp recording to identify morphological and functional distinct classes of layer 6 projection neurons in the rat primary visual cortex, which innervated separable subcortical territories. Multisite whole-cell recordings in brain slices revealed that corticoclaustral and corticothalamic layer 6 projection neurons exhibited similar somatically recorded electrophysiological properties. These classes of layer 6 projection neurons were sparsely and reciprocally synaptically interconnected, but could be differentiated by cell-class, but not target-cell-dependent rules of use-dependent depression and facilitation of unitary excitatory synaptic output. Corticoclaustral and corticothalamic layer 6 projection neurons were differentially innervated by columnar excitatory circuitry, with corticoclaustral, but not corticothalamic, neurons powerfully driven by layer 4 pyramidal neurons, and long-range pathways conveyed in neocortical layer 1. Our results therefore reveal projection target-specific, functionally distinct, streams of layer 6 output in the rodent neocortex.

Tandem Solar Cells from Accessible Low Band-Gap Polymers Using an Efficient Interconnecting Layer.

PubMed

Bag, Santanu; Patel, Romesh J; Bunha, Ajaykumar; Grand, Caroline; Berrigan, J Daniel; Dalton, Matthew J; Leever, Benjamin J; Reynolds, John R; Durstock, Michael F

2016-01-13

Tandem solar cell architectures are designed to improve device photoresponse by enabling the capture of wider range of solar spectrum as compared to single-junction device. However, the practical realization of this concept in bulk-heterojunction polymer systems requires the judicious design of a transparent interconnecting layer compatible with both polymers. Moreover, the polymers selected should be readily synthesized at large scale (>1 kg) and high performance. In this work, we demonstrate a novel tandem polymer solar cell that combines low band gap poly isoindigo [P(T3-iI)-2], which is easily synthesized in kilogram quantities, with a novel Cr/MoO3 interconnecting layer. Cr/MoO3 is shown to be greater than 80% transparent above 375 nm and an efficient interconnecting layer for P(T3-iI)-2 and PCDTBT, leading to 6% power conversion efficiencies under AM 1.5G illumination. These results serve to extend the range of interconnecting layer materials for tandem cell fabrication by establishing, for the first time, that a thin, evaporated layer of Cr/MoO3 can work as an effective interconnecting layer in a tandem polymer solar cells made with scalable photoactive materials.

Interconnections of the visual cortex with the frontal cortex in the rat.

PubMed

Sukekawa, K

1988-01-01

Horseradish peroxidase conjugated to wheat germ agglutinin (WGA-HRP) and autoradiography of tritiated leucine were used to trace the cortical origins and terminations of the connections between the visual and frontal cortices in the rat. Ipsilateral reciprocal connections between each subdivision of the visual cortex (areas 17, 18a and 18b) and the posterior half of the medial part of the frontal agranular cortex (PAGm), and their laminar organizations were confirmed. These connections did not appear to have a significant topographic organization. Although in areas 17 and 18b terminals or cells of origin in this fiber system were confined to the anterior half of these cortices, in area 18a they were observed spanning the anteroposterior extent of this cortex, with in part a column like organization. No evidence could be found for the participation of both the posterior parts of areas 17 and 18b and the anterior half of this frontal agranular cortex in these connections. Fibers from each subdivision of the visual cortex to the PAGm terminated predominantly in the lower part of layer I and in layer II. In area 17, this occipito-frontal projection was found to arise from the scattered pyramidal cells in layer V and more prominently from pyramidal cells in layer V of area 17/18a border. In area 18a, the fibers projecting to the PAGm originated mainly from pyramidal cells primarily in layer V and to a lesser extent in layers II, III and VI. Whereas in area 18b, this projection was found to arise mainly from pyramidal cells in layers II and III, to a lesser extent in layers V and VI, and less frequent in layer IV. On the other hand, the reciprocal projection to the visual cortex was found to originate largely from pyramidal cells in layers III and V of the PAGm. In areas 17 and 18a, these fibers terminated in layers I and VI, and in layers I, V and VI, respectively. Whereas in area 18b, they were distributed throughout all layers except layer II.

Inversion layer MOS solar cells

NASA Technical Reports Server (NTRS)

Ho, Fat Duen

1986-01-01

Inversion layer (IL) Metal Oxide Semiconductor (MOS) solar cells were fabricated. The fabrication technique and problems are discussed. A plan for modeling IL cells is presented. Future work in this area is addressed.

Fabrication of a multi-layer three-dimensional scaffold with controlled porous micro-architecture for application in small intestine tissue engineering.

PubMed

Knight, Toyin; Basu, Joydeep; Rivera, Elias A; Spencer, Thomas; Jain, Deepak; Payne, Richard

2013-01-01

Various methods can be employed to fabricate scaffolds with characteristics that promote cell-to-material interaction. This report examines the use of a novel technique combining compression molding with particulate leaching to create a unique multi-layered scaffold with differential porosities and pore sizes that provides a high level of control to influence cell behavior. These cell behavioral responses were primarily characterized by bridging and penetration of two cell types (epithelial and smooth muscle cells) on the scaffold in vitro. Larger pore sizes corresponded to an increase in pore penetration, and a decrease in pore bridging. In addition, smaller cells (epithelial) penetrated further into the scaffold than larger cells (smooth muscle cells). In vivo evaluation of a multi-layered scaffold was well tolerated for 75 d in a rodent model. This data shows the ability of the components of multi-layered scaffolds to influence cell behavior, and demonstrates the potential for these scaffolds to promote desired tissue outcomes in vivo.

Encapsulant Material For Solar Cell Module And Laminated Glass Applications

DOEpatents

Hanoka, Jack I.; Klemchuk, Peter P.

2001-02-13

An encapsulant material includes a layer of metallocene polyethylene disposed between two layers of an acid copolymer of polyethylene. More specifically, the layer of metallocene polyethylene is disposed adjacent a rear surface of the first layer of the acid copolymer of polyethylene, and a second layer of the acid copolymer of polyethlene is disposed adjacent a rear surface of the layer of metallocene polyethylene. The encapsulant material can be used in solar cell module and laminated glass applications.

Techno-economic analysis of three different substrate removal and reuse strategies for III-V solar cells: Techno-economic analysis for III-V solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, J. Scott; Remo, Timothy; Horowitz, Kelsey

The high cost of wafers suitable for epitaxial deposition of III-V solar cells has been a primary barrier to widespread use of these cells in low-concentration and one-sun terrestrial solar applications. A possible solution is to reuse the substrate many times, thus spreading its cost across many cells. We performed a bottom-up techno-economic analysis of three different strategies for substrate reuse in high-volume manufacturing: epitaxial lift-off, spalling, and the use of a porous germanium release layer. The analysis shows that the potential cost reduction resulting from substrate reuse is limited in all three strategies--not by the number of reuse cyclesmore » achievable, but by the costs that are incurred in each cycle to prepare the substrate for another epitaxial deposition. The dominant substrate-preparation cost component is different for each of the three strategies, and the cost-ranking of these strategies is subject to change if future developments substantially reduce the cost of epitaxial deposition.« less

Basic Components of Vascular Connective Tissue and Extracellular Matrix.

PubMed

Halper, Jaroslava

2018-01-01

Though the composition of the three layers constituting the blood vessel wall varies among the different types of blood vessels, and some layers may even be missing in capillaries, certain basic components, and properties are shared by all blood vessels, though each histologically distinct layer contains a unique complement of extracellular components, growth factors and cytokines, and cell types as well. The structure and composition of vessel layers informs and is informed by the function of the particular blood vessel. The adaptation of the composition and the resulting function of the extracellular matrix (ECM) to changes in circulation/blood flow and a variety of other extravascular stimuli can be characterized as remodeling spearheaded by vascular cells. There is a surprising amount of cell traffic among the three layers. It starts with endothelial cell mediated transmigration of inflammatory cells from the bloodstream into the subendothelium, and then into tissue adjoining the blood vessel. Smooth muscle cells and a variety of adventitial cells reside in tunica media and tunica externa, respectively. The latter cells are a mixture of progenitor/stem cells, fibroblasts, myofibroblasts, pericytes, macrophages, and dendritic cells and respond to endothelial injury by transdifferentiation as they travel into the two inner layers, intima and media for corrective mission in the ECM composition. This chapter addresses the role of various vascular cell types and ECM components synthesized by them in maintenance of normal structure and in their contribution to major pathological processes, such as atherosclerosis, organ fibrosis, and diabetic retinopathy. © 2018 Elsevier Inc. All rights reserved.

Neurons and terminals in the retrohippocampal region in the rat's brain identified by anti-gamma-aminobutyric acid and anti-glutamic acid decarboxylase immunocytochemistry.

PubMed

Köhler, C; Wu, J Y; Chan-Palay, V

1985-01-01

The distribution of gamma-aminobutyric acid (GABA) containing nerve cells and terminals was studied at the light and electron microscopic levels in the retrohippocampal region of the rat by using anti-glutamic acid decarboxylase (GAD) and anti-GABA antibodies in immunocytochemistry. Large numbers of GAD and GABA stained cells were found in all retrohippocampal structures. At the ultrastructural level, the immunoreactivity against GABA and against the synthesizing enzyme GAD was localized to cytoplasmic structures, including loose clumps of rough endoplasmic reticulum, ribosomal arrays, outer mitochondrial surfaces and in axonal boutons. The GAD- and GABA-immunoreactive(-i) cells were found in all subfields of the retrohippocampal region (e.g., the subicular complex, the entorhinal area). Within the entorhinal area a slightly larger number of immunoreactive cells could be detected in layers II and III than in the other layers. In the subiculum, pre- and parasubiculum the GAD and GABA-i cells were present in relatively large numbers in all layers, except the molecular layer, which contained only a small number of GABA cells. Within the entorhinal area, GAD and GABA stained cells ranged in size from small (13 micron in diameter) to large (22 micron in diameter). A large number of different morphological classes of cells were found, except pyramidal and stellate cells. In the pre- and parasubiculum, on the other hand, the GABA cells were generally small to medium in size and morphologically more homogeneous than in the subiculum and entorhinal area. The entire retrohippocampal region was densely innervated by GABA preterminal processes, with little variation in the regional density of innervation. Within the entorhinal area, presubiculum and subiculum, a clear difference was found in the laminar pattern of innervation. In all three subfields the densest innervation was in layer II. In the entorhinal area both GAD- and GABA-i axons form palisades of fibers around the somata of neurons, which are tightly packed together in this layer. In the electron microscope both GAD-i and GABA-i were demonstrated in these axons. Axosomatic synaptic contacts were common between axons and the stellate neurons and other cells of this layer. Layers IV and VI appeared less dense in GAD-i terminals but appeared more densely innervated than layers III and V. The lamina dessicans was relatively poor in GAD-i. In the subiculum and presubiculum, as well as all other subfields of the hippocampal region, the innervation is dominated by axo-somatic innervation of layer II cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Performance enhancement of polymer electrolyte membrane fuel cells by dual-layered membrane electrode assembly structures with carbon nanotubes.

PubMed

Jung, Dong-Won; Kim, Jun-Ho; Kim, Se-Hoon; Kim, Jun-Bom; Oh, Eun-Suok

2013-05-01

The effect of dual-layered membrane electrode assemblies (d-MEAs) on the performance of a polymer electrolyte membrane fuel cell (PEMFC) was investigated using the following characterization techniques: single cell performance test, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). It has been shown that the PEMFC with d-MEAs has better cell performance than that with typical mono-layered MEAs (m-MEAs). In particular, the d-MEA whose inner layer is composed of multi-walled carbon nanotubes (MWCNTs) showed the best fuel cell performance. This is due to the fact that the d-MEAs with MWCNTs have the highest electrochemical surface area and the lowest activation polarization, as observed from the CV and EIS test.

SiN{sub x} layers on nanostructured Si solar cells: Effective for optical absorption and carrier collection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Yunae; Kim, Eunah; Gwon, Minji

2015-10-12

We compared nanopatterned Si solar cells with and without SiN{sub x} layers. The SiN{sub x} layer coating significantly improved the internal quantum efficiency of the nanopatterned cells at long wavelengths as well as short wavelengths, whereas the surface passivation helped carrier collection of flat cells mainly at short wavelengths. The surface nanostructured array enhanced the optical absorption and also concentrated incoming light near the surface in broad wavelength range. Resulting high density of the photo-excited carriers near the surface could lead to significant recombination loss and the SiN{sub x} layer played a crucial role in the improved carrier collection ofmore » the nanostructured solar cells.« less

Perovskite solar cells in N-I-P structure with four slot-die-coated layers

PubMed Central

Burkitt, Daniel; Searle, Justin

2018-01-01

The fabrication of perovskite solar cells in an N-I-P structure with compact titanium dioxide blocking, mesoporous titanium dioxide scaffold, single-step perovskite and hole-transport layers deposited using the slot-die coating technique is reported. Devices on fluorine-doped tin oxide-coated glass substrates with evaporated gold top contacts and four slot-die-coated layers are demonstrated, and best cells reach stabilized power conversion efficiencies of 7%. This work demonstrates the suitability of slot-die coating for the production of layers within this perovskite solar cell stack and the potential to transfer to large area and roll-to-roll manufacturing processes. PMID:29892402

In Vitro Engineering of Vascularized Tissue Surrogates

PubMed Central

Sakaguchi, Katsuhisa; Shimizu, Tatsuya; Horaguchi, Shigeto; Sekine, Hidekazu; Yamato, Masayuki; Umezu, Mitsuo; Okano, Teruo

2013-01-01

In vitro scaling up of bioengineered tissues is known to be limited by diffusion issues, specifically a lack of vasculature. Here, we report a new strategy for preserving cell viability in three-dimensional tissues using cell sheet technology and a perfusion bioreactor having collagen-based microchannels. When triple-layer cardiac cell sheets are incubated within this bioreactor, endothelial cells in the cell sheets migrate to vascularize in the collagen gel, and finally connect with the microchannels. Medium readily flows into the cell sheets through the microchannels and the newly developed capillaries, while the cardiac construct shows simultaneous beating. When additional triple-layer cell sheets are repeatedly layered, new multi-layer construct spontaneously integrates and the resulting construct becomes a vascularized thick tissue. These results confirmed our method to fabricate in vitro vascularized tissue surrogates that overcomes engineered-tissue thickness limitations. The surrogates promise new therapies for damaged organs as well as new in vitro tissue models. PMID:23419835

Fabrication of ordered bulk heterojunction organic photovoltaic cells using nanopatterning and electrohydrodynamic spray deposition methods.

PubMed

Park, Sung-Eun; Kim, Sehwan; Kim, Kangmin; Joe, Hang-Eun; Jung, Buyoung; Kim, Eunkyoung; Kim, Woochul; Min, Byung-Kwon; Hwang, Jungho

2012-12-21

Organic photovoltaic cells with an ordered heterojunction (OHJ) active layer are expected to show increased performance. In the study described here, OHJ cells were fabricated using a combination of nanoimprinting and electrohydrodynamic (EHD) spray deposition methods. After an electron donor material was nanoimprinted with a PDMS stamp (valley width: 230 nm, period: 590 nm) duplicated from a Si nanomold, an electron acceptor material was deposited onto the nanoimprinted donor layer using an EHD spray deposition method. The donor-acceptor interface layer was observed by obtaining cross-sectional images with a focused ion beam (FIB) microscope. The photocurrent generation performance of the OHJ cells was evaluated with the current density-voltage curve under air mass (AM) 1.5 conditions. It was found that the surface morphology of the electron acceptor layer affected the current and voltage outputs of the photovoltaic cells. When an electron acceptor layer with a smooth thin (250 nm above the valley of the electron donor layer) surface morphology was obtained, power conversion efficiency was as high as 0.55%. The electrohydrodynamic spray deposition method used to produce OHJ photovoltaic cells provides a means for the adoption of large area, high throughput processes.

The Use of Feature Parameters to Asses Barrier Properties of ALD coatings for Flexible PV Substrates

NASA Astrophysics Data System (ADS)

Blunt, Liam; Robbins, David; Fleming, Leigh; Elrawemi, Mohamed

2014-03-01

This paper reports on the recent work carried out as part of the EU funded NanoMend project. The project seeks to develop integrated process inspection, cleaning, repair and control systems for nano-scale thin films on large area substrates. In the present study flexible photovoltaic films have been the substrate of interest. Flexible PV films are the subject of significant development at present and the latest films have efficiencies at or beyond the level of Si based rigid PV modules. These flexible devices are fabricated on polymer film by the repeated deposition, and patterning, of thin layer materials using roll-to-roll processes, where the whole film is approximately 3um thick prior to encapsulation. Whilst flexible films offer significant advantages in terms of mass and the possibility of building integration (BIPV) they are at present susceptible to long term environmental degradation as a result of water vapor transmission through the barrier layers to the CIGS (Copper Indium Gallium Selenide CuInxGa(1-x)Se2) PV cells thus causing electrical shorts and efficiency drops. Environmental protection of the GIGS cell is provided by a thin (40nm) barrier coating of Al2O3. The highly conformal aluminium oxide barrier layer is produced by atomic layer deposition (ALD) where, the ultra-thin Al2O3 layer is deposited onto polymer thin films before these films encapsulate the PV cell. The surface of the starting polymer film must be of very high quality in order to avoid creating defects in the device layers. Since these defects reduce manufacturing yield, in order to prevent them, a further thin polymer coating (planarization layer) is generally applied to the polymer film prior to deposition. The presence of surface irregularities on the uncoated film can create defects within the nanometre-scale, aluminium oxide, barrier layer and these are measured and characterised. This paper begins by reporting the results of early stage measurements conducted to characterise the uncoated and coated polymer film surface topography using feature parameter analysis. The measurements are carried out using a Taylor Hobson Coherence Correlation Interferometer an optical microscope and SEM. Feature parameter analysis allows the efficient separation of small insignificant defects from large defects. The presence of both large and insignificant defects is then correlated with the water vapour transmission rate as measured on representative sets of films using at standard MOCON test. The paper finishes by drawing conclusions based on analysis of WVTR and defect size, where it is postulated that small numbers of large defects play a significant role in higher levels of WVTR.

In Vivo Multiphoton Microscopy for Investigating Biomechanical Properties of Human Skin.

PubMed

Liang, Xing; Graf, Benedikt W; Boppart, Stephen A

2011-06-01

The biomechanical properties of living cells depend on their molecular building blocks, and are important for maintaining structure and function in cells, the extracellular matrix, and tissues. These biomechanical properties and forces also shape and modify the cellular and extracellular structures under stress. While many studies have investigated the biomechanics of single cells or small populations of cells in culture, or the properties of organs and tissues, few studies have investigated the biomechanics of complex cell populations in vivo. With the use of advanced multiphoton microscopy to visualize in vivo cell populations in human skin, the biomechanical properties are investigated in a depth-dependent manner in the stratum corneum and epidermis using quasi-static mechanical deformations. A 2D elastic registration algorithm was used to analyze the images before and after deformation to determine displacements in different skin layers. In this feasibility study, the images and results from one human subject demonstrate the potential of the technique for revealing differences in elastic properties between the stratum corneum and the rest of the epidermis. This interrogational imaging methodology has the potential to enable a wide range of investigations for understanding how the biomechanical properties of in vivo cell populations influence function in health and disease.

Characterizing motility dynamics in human RPE cells

NASA Astrophysics Data System (ADS)

Liu, Zhuolin; Kurokawa, Kazuhiro; Zhang, Furu; Miller, Donald T.

2017-02-01

Retinal pigment epithelium (RPE) cells are vital to health of the outer retina, however, are often compromised in ageing and ocular diseases that lead to blindness. Early manifestation of RPE disruption occurs at the cellular level, but while in vivo biomarkers at this scale hold considerable promise, RPE cells have proven extremely challenging to image in the living human eye. Recently we addressed this problem by using organelle motility as a novel contrast agent to enhance the RPE cell in conjunction with 3D resolution of adaptive optics-optical coherence tomography (AO-OCT) to section the RPE layer. In this study, we expand on the central novelty of our method - organelle motility - by characterizing the dynamics of the motility in individual RPE cells, important because of its direct link to RPE physiology. To do this, AO-OCT videos of the same retinal patch were acquired at approximately 1 min intervals or less, time stamped, and registered in 3D with sub-cellular accuracy. Motility was quantified by an exponential decay time constant, the time for motility to decorrelate the speckle field across an RPE cell. In two normal subjects, we found the decay time constant to be just 3 seconds, thus indicating rapid motility in normal RPE cells.

Series interconnected photovoltaic cells and method for making same

DOEpatents

Albright, S.P.; Chamberlin, R.R.; Thompson, R.A.

1995-01-31

A novel photovoltaic module and method for constructing the same are disclosed. The module includes a plurality of photovoltaic cells formed on a substrate and laterally separated by interconnection regions. Each cell includes a bottom electrode, a photoactive layer and a top electrode layer. Adjacent cells are connected in electrical series by way of a conductive-buffer line. The buffer line is also useful in protecting the bottom electrode against severing during downstream layer cutting processes. 11 figs.

Actual Proliferating Index and p53 protein expression as prognostic marker in odontogenic cysts.

PubMed

Gadbail, A R; Chaudhary, M; Patil, S; Gawande, M

2009-10-01

The purpose of this study was to evaluate the biological aggressiveness of odontogenic keratocyst/keratocystic odontogenic tumour (KCOT), radicular cyst (RC) and dentigerous cyst (DC) by observing the actual proliferative activity of epithelium, and p53 protein expression. The actual proliferative activity was measured by Ki-67 Labelling Index and argyrophilic nucleolar organizing regions (AgNOR) count per nucleus. The p53 protein expression was also evaluated. Ki-67 positive cells were observed higher in suprabasal cell layers of KCOT with uniform distribution, a few of them were predominantly observed in basal cell layer in RC and DC. The AgNOR count was significantly higher in suprabasal cell layers of KCOT. The actual proliferative activity was noted to be higher in suprabasal cell layers of KCOT. The p53 immunolabelling was dense and scattered in basal and suprabasal cell layers in KCOT. The weakly stained p53 positive cells were observed diffusely distributed in KCOT, whereas they were mainly seen in basal cell layer of RC and DC. The quantitative and qualitative differences of the proliferative activity and the p53 protein expression in sporadic KCOT may be associated with intrinsic growth potential that could play a role in its development and explain locally aggressive biological behaviour. AgNOR count and p53 protein detection in odontogenic lesions can be of great consequence to predict the biological behaviour and prognosis.

Patterns of oriented cell division during the steady-state morphogenesis of the body column in hydra.

PubMed

Shimizu, H; Bode, P M; Bode, H R

1995-12-01

In an adult hydra, the tissue of the body column is in a dynamic state. The epithelial cells of both layers are constantly in the mitotic cycle. As the tissue expands, it is continuously displaced along the body axis in either an apical or basal direction, but not in a circumferential direction. Using a modified whole mount method we examined the orientation of mitotic spindles to determine what role the direction of cell division plays in axial displacement. Surprisingly, the direction of cell division was found to differ in the two epithelial layers. In the ectoderm it was somewhat biased in an axial direction. In the endoderm it was strongly biased in a circumferential direction. For both layers, the directional biases occurred throughout the length of the body column, with some regional variation in its extent. As buds developed into adults, the bias in each layer increased from an almost random distribution to the distinctly different orientations of the adult. Thus, to maintain the observed axial direction of tissue displacement, rearrangement of the epithelial cells of both layers must occur continuously in the adult as well as in developing animals. How the locomotory and contractile behavior of the muscle processes of the epithelial cells may effect changes in cell shape, and thereby influence the direction of cell division in each layer, is discussed.

Method of fabricating a solar cell

DOEpatents

Pass, Thomas; Rogers, Robert

2016-02-16

Methods of fabricating solar cells are described. A porous layer may be formed on a surface of a substrate, the porous layer including a plurality of particles and a plurality of voids. A solution may be dispensed into one or more regions of the porous layer to provide a patterned composite layer. The substrate may then be heated.

Method of fabricating a solar cell

DOEpatents

Pass, Thomas; Rogers, Robert

2014-02-25

Methods of fabricating solar cells are described. A porous layer may be formed on a surface of a substrate, the porous layer including a plurality of particles and a plurality of voids. A solution may be dispensed into one or more regions of the porous layer to provide a patterned composite layer. The substrate may then be heated.

Homogeneous-oxide stack in IGZO thin-film transistors for multi-level-cell NAND memory application

NASA Astrophysics Data System (ADS)

Ji, Hao; Wei, Yehui; Zhang, Xinlei; Jiang, Ran

2017-11-01

A nonvolatile charge-trap-flash memory that is based on amorphous indium-gallium-zinc-oxide thin film transistors was fabricated with a homogeneous-oxide structure for a multi-level-cell application. All oxide layers, i.e., tunneling layer, charge trapping layer, and blocking layer, were fabricated with Al2O3 films. The fabrication condition (including temperature and deposition method) of the charge trapping layer was different from those of the other oxide layers. This device demonstrated a considerable large memory window of 4 V between the states fully erased and programmed with the operation voltage less than 14 V. This kind of device shows a good prospect for multi-level-cell memory applications.

Inverted bulk-heterojunction solar cell with cross-linked hole-blocking layer

PubMed Central

Udum, Yasemin; Denk, Patrick; Adam, Getachew; Apaydin, Dogukan H.; Nevosad, Andreas; Teichert, Christian; S. White, Matthew.; S. Sariciftci, Niyazi.; Scharber, Markus C.

2014-01-01

We have developed a hole-blocking layer for bulk-heterojunction solar cells based on cross-linked polyethylenimine (PEI). We tested five different ether-based cross-linkers and found that all of them give comparable solar cell efficiencies. The initial idea that a cross-linked layer is more solvent resistant compared to a pristine PEI layer could not be confirmed. With and without cross-linking, the PEI layer sticks very well to the surface of the indium–tin–oxide electrode and cannot be removed by solvents used to process PEI or common organic semiconductors. The cross-linked PEI hole-blocking layer functions for multiple donor–acceptor blends. We found that using cross-linkers improves the reproducibility of the device fabrication process. PMID:24817837

Documentation and analysis of a geographic information system application for combining data layers, using nonpoint-source pollution as an example

USGS Publications Warehouse

Kiesler, James L.

2002-01-01

An analysis of the application indicates that the selected data layers to be combined should be at the greatest spatial resolution possible; however, all data layers do not have to be at the same spatial resolution. The spatial variation of the data layers should be adequately defined. The size of each grid cell should be small enough to maintain the spatial definition of smaller features within the data layers. The most accurate results are shown to occur when the values for the grid cells representing the individual data layers are summed and the mean of the summed grid-cell values is used to describe the watershed of interest.

Impact of molybdenum out diffusion and interface quality on the performance of sputter grown CZTS based solar cells.

PubMed

Dalapati, Goutam Kumar; Zhuk, Siarhei; Masudy-Panah, Saeid; Kushwaha, Ajay; Seng, Hwee Leng; Chellappan, Vijila; Suresh, Vignesh; Su, Zhenghua; Batabyal, Sudip Kumar; Tan, Cheng Cheh; Guchhait, Asim; Wong, Lydia Helena; Wong, Terence Kin Shun; Tripathy, Sudhiranjan

2017-05-02

We have investigated the impact of Cu 2 ZnSnS 4 -Molybdenum (Mo) interface quality on the performance of sputter-grown Cu 2 ZnSnS 4 (CZTS) solar cell. Thin film CZTS was deposited by sputter deposition technique using stoichiometry quaternary CZTS target. Formation of molybdenum sulphide (MoS x ) interfacial layer is observed in sputter grown CZTS films after sulphurization. Thickness of MoS x layer is found ~142 nm when CZTS layer (550 nm thick) is sulphurized at 600 °C. Thickness of MoS x layer significantly increased to ~240 nm in case of thicker CZTS layer (650 nm) under similar sulphurization condition. We also observe that high temperature (600 °C) annealing suppress the elemental impurities (Cu, Zn, Sn) at interfacial layer. The amount of out-diffused Mo significantly varies with the change in sulphurization temperature. The out-diffused Mo into CZTS layer and reconstructed interfacial layer remarkably decreases series resistance and increases shunt resistance of the solar cell. The overall efficiency of the solar cell is improved by nearly five times when 600 °C sulphurized CZTS layer is applied in place of 500 °C sulphurized layer. Molybdenum and sulphur diffusion reconstruct the interface layer during heat treatment and play the major role in charge carrier dynamics of a photovoltaic device.

Fuel cell with electrolyte feed system

DOEpatents

Feigenbaum, Haim

1984-01-01

A fuel cell having a pair of electrodes at the sites of electrochemical reactions of hydrogen and oxygen and a phosphoric acid electrolyte provided with an electrolyte supporting structure in the form of a laminated matrix assembly disposed between the electrodes. The matrix assembly is formed of a central layer disposed between two outer layers, each being permeable to the flow of the electrolyte. The central layer is provided with relatively large pores while the outer layers are provided with relatively small pores. An external reservoir supplies electrolyte via a feed means to the central layer to compensate for changes in electrolyte volume in the matrix assembly during the operation of fuel cell.

Structural changes of oviduct of freshwater shrimp, Macrobrachium nipponense (Decapoda, Palaemonidae), during spawning*

PubMed Central

Lu, Jian-ping; Zhang, Xiao-hui; Yu, Xiao-yun

2006-01-01

The structural change of the oviduct of freshwater shrimp (Macrobrachium nipponense) during spawning was examined by electron microscopy. The oviduct wall structural characteristics seem to be influenced significantly by the spawning process. Before the parturition and ovulation, two types of epithelial cells (types I and II) are found in the epithelium. The free surfaces of type I and type II cells have very dense long microvilli. Under the type I and type II cells, are a relatively thick layer of secreting material and a layer of mostly dead cells. After ovulation, two other types of epithelial cells (types III and IV) are found in the oviduct wall epithelium. The free surface of type III cells only has short microvilli scattered on the surface. The thick layer with secreting material and the dead cell layer disappeared at this stage. In some type III cells, the leaking out of cytoplasm from broken cell membrane led to the death of these type III cells. The transformation of all four types of epithelial cells was in the order: IV→I→II→III. PMID:16365928

Spatial Atmospheric Pressure Atomic Layer Deposition of Tin Oxide as an Impermeable Electron Extraction Layer for Perovskite Solar Cells with Enhanced Thermal Stability.

PubMed

Hoffmann, Lukas; Brinkmann, Kai O; Malerczyk, Jessica; Rogalla, Detlef; Becker, Tim; Theirich, Detlef; Shutsko, Ivan; Görrn, Patrick; Riedl, Thomas

2018-02-14

Despite the notable success of hybrid halide perovskite-based solar cells, their long-term stability is still a key-issue. Aside from optimizing the photoactive perovskite, the cell design states a powerful lever to improve stability under various stress conditions. Dedicated electrically conductive diffusion barriers inside the cell stack, that counteract the ingress of moisture and prevent the migration of corrosive halogen species, can substantially improve ambient and thermal stability. Although atomic layer deposition (ALD) is excellently suited to prepare such functional layers, ALD suffers from the requirement of vacuum and only allows for a very limited throughput. Here, we demonstrate for the first time spatial ALD-grown SnO x at atmospheric pressure as impermeable electron extraction layers for perovskite solar cells. We achieve optical transmittance and electrical conductivity similar to those in SnO x grown by conventional vacuum-based ALD. A low deposition temperature of 80 °C and a high substrate speed of 2.4 m min -1 yield SnO x layers with a low water vapor transmission rate of ∼10 -4 gm -2 day -1 (at 60 °C/60% RH). Thereby, in perovskite solar cells, dense hybrid Al:ZnO/SnO x electron extraction layers are created that are the key for stable cell characteristics beyond 1000 h in ambient air and over 3000 h at 60 °C. Most notably, our work of introducing spatial ALD at atmospheric pressure paves the way to the future roll-to-roll manufacturing of stable perovskite solar cells.

Accelerated cell-sheet recovery from a surface successively grafted with polyacrylamide and poly(N-isopropylacrylamide).

PubMed

Akiyama, Yoshikatsu; Kikuchi, Akihiko; Yamato, Masayuki; Okano, Teruo

2014-08-01

A double polymeric nanolayer consisting of poly(N-isopropylacrylamide) (PIPAAm) and hydrophilic polyacrylamide (PAAm) was deposited on tissue culture polystyrene (TCPS) surfaces using electron beam irradiation to form a new temperature-responsive cell culture surface in which the basal hydrophilic PAAm component in the double polymeric layer promotes the hydration of the upper PIPAAm layer and induces rapid cell detachment compared to a conventional temperature-responsive cell culture surface, PIPAAm-grafted TCPS (PIPAAm-TCPS). Take-off angle-dependent X-ray photoelectron spectroscopy spectral analysis demonstrated that the grafted PIPAAm and PAAm components were located in the upper and basal regions of the double polymeric layer, respectively, suggesting that the double polymeric layer forms an inter-penetrating-network-like structure with PAAm at the basal portion of the PIPAAm grafted chains. The wettability of the temperature-responsive cell culture surfaces with the double polymeric layer tended to be more hydrophilic, with an increase in the basal PAAm graft density at a constant PIPAAm graft density. However, when the graft densities of the upper PIPAAm and basal PAAm were optimized, the resulting temperature-responsive cell culture surface with the double polymeric layer exhibited rapid cell detachment while maintaining cell adhesive character comparable to that of PIPAAm-TCPS. The cell adhesive character was altered from cell-adhesive to cell-repellent with increasing PAAm or PIPAAm graft density. The cell adhesive character of the temperature-responsive cell culture surfaces was relatively consistent with their contact angles. These results strongly suggest that the basal PAAm surface properties affect the degree of hydration and dehydration of the subsequently grafted PIPAAm. In addition, the roles of the hydrophilic component in accelerating cell detachment are further discussed in terms of the mobility of the grafted PIPAAm chains. Applications of this insight might be useful for designing temperature-responsive cell culture surfaces for achieving efficient cell culture and quick target cell detachment. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

3D Imaging of Retinal Pigment Epithelial Cells in the Living Human Retina

PubMed Central

Liu, Zhuolin; Kocaoglu, Omer P.; Miller, Donald T.

2016-01-01

Purpose Dysfunction of the retinal pigment epithelium (RPE) underlies numerous retinal pathologies, but biomarkers sensitive to RPE change at the cellular level are limited. In this study, we used adaptive optics optical coherence tomography (AO-OCT) in conjunction with organelle motility as a novel contrast mechanism to visualize RPE cells and characterize their 3-dimensional (3D) reflectance profile. Methods Using the Indiana AO-OCT imaging system (λc = 790 nm), volumes were acquired in the macula of six normal subjects (25–61 years). Volumes were registered in 3D with subcellular accuracy, layers segmented, and RPE and photoreceptor en face images extracted and averaged. Voronoi and two-dimensional (2D) power spectra analyses were applied to the images to quantify RPE and cone packing and cone-to-RPE ratio. Results Adaptive optics OCT revealed two distinct reflectance patterns at the depth of the RPE. One is characterized by the RPE interface with rod photoreceptor tips, the second by the RPE cell nuclei and surrounding organelles, likely melanin. Increasing cell contrast by averaging proved critical for observing the RPE cell mosaic, successful in all subjects and retinal eccentricities imaged. Retinal pigment epithelium mosaic packing and cell thickness generally agreed with that of histology and in vivo studies using other imaging modalities. Conclusions We have presented, to our knowledge, the first detailed characterization of the 3D reflectance profile of individual RPE cells and their relation to cones and rods in the living human retina. Success in younger and older eyes establishes a path for testing aging effects in larger populations. Because the technology is based on OCT, our measurements will aid in interpreting clinical OCT images. PMID:27472277

Quantum well multijunction photovoltaic cell

DOEpatents

Chaffin, R.J.; Osbourn, G.C.

1983-07-08

A monolithic, quantum well, multilayer photovoltaic cell comprises a p-n junction comprising a p-region on one side and an n-region on the other side, each of which regions comprises a series of at least three semiconductor layers, all p-type in the p-region and all n-type in the n-region; each of said series of layers comprising alternating barrier and quantum well layers, each barrier layer comprising a semiconductor material having a first bandgap and each quantum well layer comprising a semiconductor material having a second bandgap when in bulk thickness which is narrower than said first bandgap, the barrier layers sandwiching each quantum well layer and each quantum well layer being sufficiently thin that the width of its bandgap is between said first and second bandgaps, such that radiation incident on said cell and above an energy determined by the bandgap of the quantum well layers will be absorbed and will produce an electrical potential across said junction.

Quantum well multijunction photovoltaic cell

DOEpatents

Chaffin, Roger J.; Osbourn, Gordon C.

1987-01-01

A monolithic, quantum well, multilayer photovoltaic cell comprises a p-n junction comprising a p-region on one side and an n-region on the other side, each of which regions comprises a series of at least three semiconductor layers, all p-type in the p-region and all n-type in the n-region; each of said series of layers comprising alternating barrier and quantum well layers, each barrier layer comprising a semiconductor material having a first bandgap and each quantum well layer comprising a semiconductor material having a second bandgap when in bulk thickness which is narrower than said first bandgap, the barrier layers sandwiching each quantum well layer and each quantum well layer being sufficiently thin that the width of its bandgap is between said first and second bandgaps, such that radiation incident on said cell and above an energy determined by the bandgap of the quantum well layers will be absorbed and will produce an electrical potential across said junction.

Daughters of the Enamel Organ: Development, Fate, and Function of the Stratum Intermedium, Stellate Reticulum, and Outer Enamel Epithelium

PubMed Central

Liu, Hui; Yan, Xiulin; Pandya, Mirali; Luan, Xianghong

2016-01-01

The tooth enamel organ (EO) is a complex epithelial cell assembly involved in multiple aspects of tooth development, including amelogenesis. The present study focuses on the role of the nonameloblast layers of the EO, the stratum intermedium, the stellate reticulum, and the outer enamel epithelium (OEE). The secretory stage stratum intermedium was distinguished by p63-positive epithelial stem cell marks, highly specific alkaline phosphatase labeling, as well as multiple desmosomes and gap junctions. At the location of the presecretory stage stellate reticulum, the pre-eruption EO prominently featured the papillary layer (PL) as a keratin immunopositive network of epithelial strands between tooth crowns and oral epithelium. PL cell strands contained numerous p63-positive epithelial stem cells, while BrdU proliferative cells were detected at the outer boundaries of the PL, suggesting that the stellate reticulum/PL epithelial cell sheath proliferated to facilitate an epithelial seal during tooth eruption. Comparative histology studies demonstrated continuity between the OEE and the general lamina of continuous tooth replacement in reptiles, and the outer layer of Hertwig's epithelial root sheath in humans, implicating the OEE as the formative layer for continuous tooth replacement and tooth root extension. Cell fate studies in organ culture verified that the cervical portion of the mouse molar EO gave rise to Malassez rest-like cell islands. Together, these studies indicate that the nonameloblast layers of the EO play multiple roles during odontogenesis, including the maintenance of several p63-positive stem cell reservoirs, a role during tooth root morphogenesis and tooth succession, a stabilizing function for the ameloblast layer, the facilitation of ion transport from the EO capillaries to the enamel layer, as well as safe and seamless tooth eruption. PMID:27611344

Daughters of the Enamel Organ: Development, Fate, and Function of the Stratum Intermedium, Stellate Reticulum, and Outer Enamel Epithelium.

PubMed

Liu, Hui; Yan, Xiulin; Pandya, Mirali; Luan, Xianghong; Diekwisch, Thomas G H

2016-09-09

The tooth enamel organ (EO) is a complex epithelial cell assembly involved in multiple aspects of tooth development, including amelogenesis. The present study focuses on the role of the nonameloblast layers of the EO, the stratum intermedium, the stellate reticulum, and the outer enamel epithelium (OEE). The secretory stage stratum intermedium was distinguished by p63-positive epithelial stem cell marks, highly specific alkaline phosphatase labeling, as well as multiple desmosomes and gap junctions. At the location of the presecretory stage stellate reticulum, the pre-eruption EO prominently featured the papillary layer (PL) as a keratin immunopositive network of epithelial strands between tooth crowns and oral epithelium. PL cell strands contained numerous p63-positive epithelial stem cells, while BrdU proliferative cells were detected at the outer boundaries of the PL, suggesting that the stellate reticulum/PL epithelial cell sheath proliferated to facilitate an epithelial seal during tooth eruption. Comparative histology studies demonstrated continuity between the OEE and the general lamina of continuous tooth replacement in reptiles, and the outer layer of Hertwig's epithelial root sheath in humans, implicating the OEE as the formative layer for continuous tooth replacement and tooth root extension. Cell fate studies in organ culture verified that the cervical portion of the mouse molar EO gave rise to Malassez rest-like cell islands. Together, these studies indicate that the nonameloblast layers of the EO play multiple roles during odontogenesis, including the maintenance of several p63-positive stem cell reservoirs, a role during tooth root morphogenesis and tooth succession, a stabilizing function for the ameloblast layer, the facilitation of ion transport from the EO capillaries to the enamel layer, as well as safe and seamless tooth eruption.

ON Cone Bipolar Cell Axonal Synapses in the OFF Inner Plexiform Layer of the Rabbit Retina

PubMed Central

Lauritzen, J. Scott; Anderson, James R.; Jones, Bryan W.; Watt, Carl B.; Mohammed, Shoeb; Hoang, John V.; Marc, Robert E.

2012-01-01

Analysis of the rabbit retinal connectome RC1 reveals that the division between the ON and OFF inner plexiform layer (IPL) is not structurally absolute. ON cone bipolar cells make non-canonical axonal synapses onto specific targets and receive amacrine cell synapses in the nominal OFF layer, creating novel motifs, including inhibitory crossover networks. Automated transmission electron microscope (ATEM) imaging, molecular tagging, tracing, and rendering of ≈ 400 bipolar cells reveals axonal ribbons in 36% of ON cone bipolar cells, throughout the OFF IPL. The targets include GABA-positive amacrine cells (γACs), glycine-positive amacrine cells (GACs) and ganglion cells. Most ON cone bipolar cell axonal contacts target GACs driven by OFF cone bipolar cells, forming new architectures for generating ON-OFF amacrine cells. Many of these ON-OFF GACs target ON cone bipolar cell axons, ON γACs and/or ON-OFF ganglion cells, representing widespread mechanisms for OFF to ON crossover inhibition. Other targets include OFF γACs presynaptic to OFF bipolar cells, forming γAC-mediated crossover motifs. ON cone bipolar cell axonal ribbons drive bistratified ON-OFF ganglion cells in the OFF layer and provide ON drive to polarity-appropriate targets such as bistratified diving ganglion cells (bsdGCs). The targeting precision of ON cone bipolar cell axonal synapses shows that this drive incidence is necessarily a joint distribution of cone bipolar cell axonal frequency and target cell trajectories through a given volume of the OFF layer. Such joint distribution sampling is likely common when targets are sparser than sources and when sources are coupled, as are ON cone bipolar cells. PMID:23042441

Identification of a novel gene cluster in the upstream region of the S-layer gene sbpA involved in cell wall metabolism of Lysinibacillus sphaericus CCM 2177 and characterization of the recombinantly produced autolysin and pyruvyl transferase.

PubMed

Pleschberger, Magdalena; Hildner, Florian; Rünzler, Dominik; Gelbmann, Nicola; Mayer, Harald F; Sleytr, Uwe B; Egelseer, Eva M

2013-05-01

The S-layer protein SbpA of Lysinibacillus sphaericus CCM 2177 assembles into a square (p4) lattice structure and recognizes a pyruvylated secondary cell wall polymer (SCWP) as the proper anchoring structure to the rigid cell wall layer. Sequencing of 8,004 bp in the 5'-upstream region of the S-layer gene sbpA led to five ORFs-encoding proteins involved in cell wall metabolism. After cloning and heterologous expression of ORF1 and ORF5 in Escherichia coli, the recombinant autolysin rAbpA and the recombinant pyruvyl transferase rCsaB were isolated, purified, and correct folding was confirmed by circular dichroism. Although rAbpA encoded by ORF1 showed amidase activity, it could attack whole cells of Ly. sphaericus CCM 2177 only after complete extraction of the S-layer lattice. Despite the presence of three S-layer-homology motifs on the N-terminal part, rAbpA did not show detectable affinity to peptidoglycan-containing sacculi, nor to isolated SCWP. As the molecular mass of the autolysin lies above the molecular exclusion limit of the S-layer, AbpA is obviously trapped within the rigid cell wall layer by the isoporous protein lattice. Immunogold-labeling of ultrathin-sectioned whole cells of Ly. sphaericus CCM 2177 with a polyclonal rabbit antiserum raised against rCsaB encoded by ORF5, and cell fractionation experiments demonstrated that the pyruvyl transferase was located in the cytoplasm, but not associated with cell envelope components including the plasma membrane. In enzymatic assays, rCsaB clearly showed pyruvyl transferase activity. By using RT-PCR, specific transcripts for each ORF could be detected. Cotranscription could be confirmed for ORF2 and ORF3.

Interlaminar and lateral excitatory amino acid connections in the striate cortex of monkey.

PubMed

Kisvarday, Z F; Cowey, A; Smith, A D; Somogyi, P

1989-02-01

The intrinsic excitatory amino acid pathways within the striate cortex of monkeys were studied by autoradiographic detection of retrogradely labeled somata following microinjections of D-3H-aspartate (D-3H-Asp) into different layers. The labeled amino acid was selectively accumulated by subpopulations of neurons and, to a small extent, by glial cells, the latter mainly in the supragranular layers. Immunocytochemical detection of neurons containing GABA showed that, apart from a few cells exclusively in layer I, GABAergic neurons do not accumulate D-3H-Asp. Several lines of evidence suggest that D-3H-Asp uptake occurred only at nerve terminals; thus, the pattern of perikaryal labeling allowed the delineation of interlaminar and lateral projections. Neurons in layer I probably project laterally, and layer I receives wide-ranging projections from layer IVB and layer V from cells up to 1300 microns laterally. Some neurons in layer II send a focused projection to lower layer VI. Some neurons in layers II/III project up to 1 mm laterally within their own layer, but relatively few neurons can be labeled in these projections. Similarly, in layers II/III few neurons can be retrogradely labeled from layers V and upper VI, and this projection is organized such that cells closer to the pia project deeper in layer V/VI. The connections of layer IVA could not be revealed separately because of the difficulty of confining injections to this thin sublamina. Neurons in layer IVB project up to 1300 microns within IVB itself. A small number of cells from IVB also project to layers III, IVC-alpha, V, and VI with much more restricted lateral spread. Neurons in upper IVC-alpha send axons to layer IVB with at least 600-800 microns lateral spread. Neurons in lower IVC-alpha/upper IVC-beta project to layer III with at least 300-500 microns lateral spread. The bottom 50-80 microns of layer IVC-beta contains neurons with a very focused projection, apparently exclusively to the layer III/IVA border region. Both layers IVC alpha and beta have rich connections within themselves, the beta sublayer having more restricted lateral connections. Some neurons in layer IVC-beta give a laterally restricted small input to layers IVC-alpha and IVB. Both IVC-alpha and -beta project to layers V and VI, and these projections are spread at least 400 microns laterally. Neurons in layer V project to all layers, but the projection to layers I-III and within layer V itself spread much further laterally than the projections to layers IV and VI.(ABSTRACT TRUNCATED AT 400 WORDS)

Marking cell layers with spectinomycin provides a new tool for monitoring cell fate during leaf development.

PubMed

Pyke, K; Zubko, M K; Day, A

2000-10-01

Spectinomycin, an inhibitor of plastid protein synthesis, can be used to mark specific cell layers in the shoot meristem of Brassica napus. Pale yellow-green (YG) plants resulting from spectinomycin-treatment can be propagated indefinitely in vitro. Microscopic examination showed that YG-plants result from inactivation of plastids in the L2 and L3 layers and are composed of a pale green epidermis covering a white mesophyll layer. Epidermal cells of YG and normal green plants are similar and contain 10-20 small pale green plastids. YG plants are equivalent to periclinal chimeras with the important distinction that there is no genotypic difference between the white and green cell layers. Periclinal divisions of epidermal cells take place at all stages of leaf development to produce invaginations of green mesophyll located in sectors of widely varying sizes. A periclinal division rate of 1 in 3000-4000 anticlinal divisions for the adaxial epidermis, was 2-3-fold higher than that estimated for the abaxial epidermis. Analysis of white and green mesophyll showed that chloroplasts are essential for palisade cell differentiation and this requirement is cell-autonomous. Stable marking of cell lineages with spectinomycin is simple, rapid and reveals the requirement for functional plastids in cellular differentiation.

N/P GaAs concentrator solar cells with an improved grid and bushbar contact design

NASA Technical Reports Server (NTRS)

Desalvo, G. C.; Mueller, E. H.; Barnett, A. M.

1985-01-01

The major requirements for a solar cell used in space applications are high efficiency at AMO irradiance and resistance to high energy radiation. Gallium arsenide, with a band gap of 1.43 eV, is one of the most efficient sunlight to electricity converters (25%) when the the simple diode model is used to calculate efficiencies at AMO irradiance, GaAs solar cells are more radiation resistant than silicon solar cells and the N/P GaAs device has been reported to be more radiation resistant than similar P/N solar cells. This higher resistance is probably due to the fact that only 37% of the current is generated in the top N layer of the N/P cell compared to 69% in the top layer of a P/N solar cell. This top layer of the cell is most affected by radiation. It has also been theoretically calculated that the optimized N/P device will prove to have a higher efficiency than a similar P/N device. The use of a GaP window layer on a GaAs solar cell will avoid many of the inherent problems normally associated with a GaAlAs window while still proving good passivation of the GaAs surface. An optimized circular grid design for solar cell concentrators has been shown which incorporates a multi-layer metallization scheme. This multi-layer design allows for a greater current carrying capacity for a unit area of shading, which results in a better output efficiency.

Cellular interaction of a layer-by-layer based drug delivery system depending on material properties and cell types.

PubMed

Brueckner, Mandy; Jankuhn, Steffen; Jülke, Eva-Maria; Reibetanz, Uta

2018-01-01

Drug delivery systems (DDS) and their interaction with cells are a controversial topic in the development of therapeutic concepts and approaches. On one hand, DDS are very useful for protected and targeted transport of defined dosages of active agents. On the other hand, their physicochemical properties such as material, size, shape, charge, or stiffness have a huge impact on cellular uptake and intracellular processing. Additionally, even identical DDS can undergo a completely diverse interaction with different cell types. However, quite often in in vitro DDS/cell interaction experiments, those aspects are not considered and DDS and cells are randomly chosen. Hence, our investigations provide an insight into layer-by-layer designed microcarriers with modifications of only some of the most important parameters (surface charge, stiffness, and applied microcarrier/cell ratio) and their influence on cellular uptake and viability. We also considered the interaction of these differently equipped DDS with several cell types and investigated professional phagocytes (neutrophil granulocytes; macrophages) as well as non-professional phagocytes (epithelial cells) under comparable conditions. We found that even small modifications such as layer-by-layer (LbL)-microcarriers with positive or negative surface charge, or LbL-microcarriers with solid core or as hollow capsules but equipped with the same surface properties, show significant differences in interaction and viability, and several cell types react very differently to the offered DDS. As a consequence, the properties of the DDS have to be carefully chosen with respect to the addressed cell type with the aim to efficiently transport a desired agent.

Surface-Layer (S-Layer) Proteins Sap and EA1 Govern the Binding of the S-Layer-Associated Protein BslO at the Cell Septa of Bacillus anthracis

PubMed Central

Kern, Valerie J.; Kern, Justin W.; Theriot, Julie A.; Schneewind, Olaf

2012-01-01

The Gram-positive pathogen Bacillus anthracis contains 24 genes whose products harbor the structurally conserved surface-layer (S-layer) homology (SLH) domain. Proteins endowed with the SLH domain associate with the secondary cell wall polysaccharide (SCWP) following secretion. Two such proteins, Sap and EA1, have the unique ability to self-assemble into a paracrystalline layer on the surface of bacilli and form S layers. Other SLH domain proteins can also be found within the S layer and have been designated Bacillus S-layer-associated protein (BSLs). While both S-layer proteins and BSLs bind the same SCWP, their deposition on the cell surface is not random. For example, BslO is targeted to septal peptidoglycan zones, where it catalyzes the separation of daughter cells. Here we show that an insertional lesion in the sap structural gene results in elongated chains of bacilli, as observed with a bslO mutant. The chain length of the sap mutant can be reduced by the addition of purified BslO in the culture medium. This complementation in trans can be explained by an increased deposition of BslO onto the surface of sap mutant bacilli that extends beyond chain septa. Using fluorescence microscopy, we observed that the Sap S layer does not overlap the EA1 S layer and slowly yields to the EA1 S layer in a growth-phase-dependent manner. Although present all over bacilli, Sap S-layer patches are not observed at septa. Thus, we propose that the dynamic Sap/EA1 S-layer coverage of the envelope restricts the deposition of BslO to the SCWP at septal rings. PMID:22609927

Electrochemical cell with powdered electrically insulative material as a separator

DOEpatents

Mathers, James P.; Olszanski, Theodore W.; Boquist, Carl W.

1978-01-01

A secondary electrochemical cell includes electrodes separated by a layer of electrically insulative powder. The powder includes refractory materials selected from the oxides and nitrides of metals and metaloids. The powdered refractory material, blended with electrolyte particles, can be compacted in layers with electrode materials to form an integral electrode structure or separately assembled into the cell. The assembled cell is heated to operating temperature leaving porous layers of electrically insulative, refractory particles, containing molten electrolyte between the electrodes.

Follicular growth and atresia in the mouse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oakberg, E. F.

1978-01-01

Follicles were classified on the basis of number of layers of follicle cells, presence and degree of development of the zona pellucida, and presence of an antrum. Formation of an antrum in follicles with less than 7-8 cell layers and/or presence of necrotic cells was considered indicative of degeneration. When classified in this manner, the data suggest that follicles and their contained oocytes are committed to either normal development or atresia by the time a third layer of granulosa cells is formed.

Method of preparing a powdered, electrically insulative separator for use in an electrochemical cell

DOEpatents

Cooper, Tom O.; Miller, William E.

1978-01-01

A secondary electrochemical cell includes electrodes separated by a layer of electrically insulative powder. The powder includes refractory materials selected from the oxides and nitrides of metals and metaloids. The powdered refractory material, blended with electrolyte particles, is compacted as layers onto an electrode to form an integral electrode structure and assembled into the cell. The assembled cell is heated to its operating temperature leaving porous layers of electrically insulative, refractory particles, containing molten electrolyte between the electrodes.

Surgical Marking Pen Dye Inhibits Saphenous Vein Cell Proliferation and Migration in Saphenous Vein Graft Tissue

PubMed Central

Kikuchi, Shinsuke; Kenagy, Richard D; Gao, Lu; Wight, Thomas N; Azuma, Nobuyoshi; Sobel, Michael; Clowes, Alexander W

2014-01-01

Objective Markers containing dyes such as crystal violet (CAS 548-62-9) are routinely used on the adventitia of vein bypass grafts to avoid twisting during placement. Since little is known about how these dyes affect vein graft healing and function, we determined the effect of crystal violet on cell migration and proliferation, which are responses to injury after grafting. Methods Fresh human saphenous veins were obtained as residual specimens from leg bypass surgeries. Portions of the vein that had been surgically marked with crystal violet were analyzed separately from those that had no dye marking. In the laboratory, they were split into easily dissected inner and outer layers after removal of endothelium. This f cleavage plane was within the circular muscle layer of the media. Cell migration from explants was measured daily as either 1) % migration positive explants, which exclusively measures migration, or 2) the number of cells on the plastic surrounding each explant, which measures migration plus proliferation. Cell proliferation and apoptosis (Ki67 and TUNEL staining, respectively) were determined in dye-marked and unmarked areas of cultured vein rings. The dose-dependent effects of crystal violet were measured for cell migration from explants as well as proliferation, migration, and death of cultured outer layer cells. Dye was extracted from explants with ethanol and quantified by spectrophotometry. Results There was significantly less cell migration from visibly blue, compared to unstained, outer layer explants by both methods. There was no significant difference in migration from inner layer explants adjacent to blue-stained or unstained sections of vein, because dye did not penetrate to the inner layer. Ki67 staining of vein in organ culture, which is a measure of proliferation, progressively increased up to 6 days in non-blue outer layer and was abolished in the blue outer layer. Evidence of apoptosis (TUNEL staining) was present throughout the wall and not different in blue-stained and unstained vein wall segments. Blue outer layer explants had 65.9±8.0 ng dye/explant compared to 2.1±1.3 for non-blue outer layer explants. Dye applied in vitro to either outer or inner layer explants dose-dependently inhibited migration (IC50=8.5 ng/explant). The IC50s of crystal violet for outer layer cell proliferation and migration were 0.1 and 1.2 μg/ml, while the EC50 for death was between 1 and 10 μg/ml. Conclusion Crystal violet inhibits venous cell migration and proliferation indicating that alternative methods should be considered for marking vein grafts. PMID:25935273

Foveal fine structure in retinopathy of prematurity: an adaptive optics Fourier domain optical coherence tomography study.

PubMed

Hammer, Daniel X; Iftimia, Nicusor V; Ferguson, R Daniel; Bigelow, Chad E; Ustun, Teoman E; Barnaby, Amber M; Fulton, Anne B

2008-05-01

To describe the fine structure of the fovea in subjects with a history of mild retinopathy of prematurity (ROP) using adaptive optics-Fourier domain optical coherence tomography (AO-FDOCT). High-speed, high-resolution AO-FDOCT videos were recorded in subjects with a history of ROP (n = 5; age range, 14-26 years) and in control subjects (n = 5; age range, 18-25 years). Custom software was used to extract foveal pit depth and volume from three-dimensional (3-D) retinal maps. The thickness of retinal layers as a function of retinal eccentricity was measured manually. The retinal vasculature in the parafoveal region was assessed. The foveal pit was wider and shallower in ROP than in control subjects. Mean pit depth, defined from the base to the level at which the pit reaches a lateral radius of 728 microm, was 121 microm compared with 53 microm. Intact, contiguous inner retinal layers overlay the fovea in ROP subjects but were absent in the control subjects. Mean full retinal thickness at the fovea was greater in the subjects with ROP (279.0 microm vs. 190.2 microm). The photoreceptor layer thickness did not differ between ROP and control subjects. An avascular zone was not identified in the subjects with ROP but was present in all the control subjects. The foveas of subjects with a history of mild ROP have significant structural abnormalities that are probably a consequence of perturbations of neurovascular development.

Hybrid Dye-Sensitized Solar Cells Consisting of Double Titania Layers for Harvesting Light with Wide Range of Wavelengths

NASA Astrophysics Data System (ADS)

Sadamasu, Kengo; Inoue, Takafumi; Ogomi, Yuhei; Pandey, Shyam S.; Hayase, Shuzi

2011-02-01

We report a hybrid dye-sensitized solar cell consisting of double titania layers (top and bottom layers) stained with two dyes. A top layer fabricated on a glass was mechanically pressed with a bottom layer fabricated on a glass cloth. The glass cloth acts as a supporter of a porous titania layer as well as a holder of electrolyte. The incident photon to current efficiency (IPCE) curve had two peaks corresponding to those of the two dyes, which demonstrates that electrons are collected from both the top and bottom layers.

Ocular dominance in layer IV of the cat's visual cortex and the effects of monocular deprivation.

PubMed Central

Shatz, C J; Stryker, M P

1978-01-01

1. The relation between the physiological pattern of ocular dominance and the anatomical distribution of geniculocortical afferents serving each eye was studied in layer IV of the primary visual cortex of normal and monocularly deprived cats. 2. One eye was injected with radioactive label. After allowing sufficient time for transeuronal transport, micro-electrode recordings were made, and the geniculocoritcal afferents serving the injected eye were located autoradiographically. 3. In layer IV of normal cats, cell were clustered according to eye preference, and fewer cells were binocularly driven than in other layers. Points of transition between groups of cells dominated by one eye and those dominated by the other were marked with electrolytic lesions. A good correspondence was found between the location of cells dominated by the injected eye and the patches of radioactively labelled geniculocortical afferents. 4. Following prolonged early monocular deprivation, the patches of geniculocortical afferents in layer IV serving the deprived eye were smaller, and those serving the non-deprived eye larger, than normal. Again there was a coincidence between the patches of radioactively labelled afferents and the location of cells dominated by the injected eye. 5. The deprived eye was found to dominate a substantial fraction (22%) of cortical cells in the fourth layer. In other cortical layers, only 7% of the cells were dominated by the deprived eye. 6. These findings suggest that the thalamocortical projection is physically rearranged as a consequence of monocular deprivation, as has been demonstrated for layer IVc of the monkey's visual cortex (Hubel, Wiesel & Le Vay, 1977). Images Plate 1 Plate 2 Plate 3 Plate 4 Plate 5 Plate 6 PMID:702379

Multifunctional Inverse Opal-Like TiO2 Electron Transport Layer for Efficient Hybrid Perovskite Solar Cells.

PubMed

Chen, Xiao; Yang, Shuang; Zheng, Yi Chu; Chen, Ying; Hou, Yu; Yang, Xiao Hua; Yang, Hua Gui

2015-09-01

A novel multifunctional inverse opal-like TiO 2 electron transport layer (IOT-ETL) is designed to replace the traditional compact layer and mesoporous scaffold layer in perovskite solar cells (PSCs). Improved light harvesting efficiency and charge transporting performance in IOT-ETL based PSCs yield high power conversion efficiency of 13.11%.

HSPES membrane electrode assembly

NASA Technical Reports Server (NTRS)

Kindler, Andrew (Inventor); Yen, Shiao-Ping (Inventor)

2000-01-01

An improved fuel cell electrode, as well as fuel cells and membrane electrode assemblies that include such an electrode, in which the electrode includes a backing layer having a sintered layer thereon, and a non-sintered free-catalyst layer. The invention also features a method of forming the electrode by sintering a backing material with a catalyst material and then applying a free-catalyst layer.

Enhanced Charge Collection with Passivation Layers in Perovskite Solar Cells.

PubMed

Lee, Yong Hui; Luo, Jingshan; Son, Min-Kyu; Gao, Peng; Cho, Kyung Taek; Seo, Jiyoun; Zakeeruddin, Shaik M; Grätzel, Michael; Nazeeruddin, Mohammad Khaja

2016-05-01

The Al2 O3 passivation layer is beneficial for mesoporous TiO2 -based perovskite solar cells when it is deposited selectively on the compact TiO2 surface. Such a passivation layer suppressing surface recombination can be formed by thermal decomposition of the perovskite layer during post-annealing. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of superhydrophobic electrosprayed catalyst layers using a localized reference electrode technique

NASA Astrophysics Data System (ADS)

Chaparro, A. M.; Ferreira-Aparicio, P.; Folgado, M. A.; Brightman, E.; Hinds, G.

2016-09-01

The performance of electrosprayed cathode catalyst layers in a polymer electrolyte membrane fuel cell (PEMFC) is studied using a localized reference electrode technique. Single cells with an electrosprayed cathode catalyst layer show an increase of >20% in maximum power density under standard testing conditions, compared with identical cells assembled with a conventional, state-of-the-art, gas diffusion cathode. When operated at high current density (1.2 A cm-2) the electrosprayed catalyst layers show more homogeneous distribution of the localized cathode potential, with a standard deviation from inlet to outlet of <50 mV, compared with 79 mV for the conventional gas diffusion cathode. Higher performance and homogeneity of cell response is attributed to the superhydrophobic nature of the macroporous electrosprayed catalyst layer structure, which enhances the rate of expulsion of liquid water from the cathode. On the other hand, at low current densities (<0.5 A cm-2), the electrosprayed layers exhibit more heterogeneous distribution of cathode potential than the conventional cathodes; this behavior is attributed to less favorable kinetics for oxygen reduction in very hydrophobic catalyst layers. The optimum performance may be obtained with electrosprayed catalyst layers employing a high Pt/C catalyst ratio.

Triple-Layer Vascular Grafts Fabricated by Combined E-Jet 3D Printing and Electrospinning.

PubMed

Huang, Ruiying; Gao, Xiangkai; Wang, Jian; Chen, Haoxiang; Tong, Chunyi; Tan, Yongjun; Tan, Zhikai

2018-05-29

Small-diameter tissue-engineered vascular grafts are urgently needed for clinic arterial substitute. To simulate the structures and functions of natural blood vessels, we designed a novel triple-layer poly(ε-caprolactone) (PCL) fibrous vascular graft by combining E-jet 3D printing and electrospinning techniques. The resultant vascular graft consisted of an interior layer comprising 3D-printed highly aligned strong fibers, a middle layer made by electrospun densely fibers, and an exterior structure composed of mixed fibers fabricated by co-electrospraying. The biocompatible triple-layer graft was used for in vivo implantation, and results demonstrated that the longitudinally-aligned fibers within the lumen of the graft could enhance the proliferation and migration of endothelial cells, while maintained good mechanical properties. The exterior layer provided a pathway that encouraged cells to migrate into the scaffold after implantation. This experimental graft overcame the limitations of conventionally electrospun vascular grafts of inadequate porosity and lowly cell penetration. The unique structure of the triple-layer vascular graft promoted cell growth and infiltration in vivo, thus provided an encouraging substitute for in situ tissue engineering.

THE ANATOMIC SITE OF THE TRANSEPITHELIAL PERMEABILITY BARRIERS OF TOAD BLADDER

PubMed Central

DiBona, Donald R.; Civan, Mortimer M.; Leaf, Alexander

1969-01-01

An examination of the mucosal epithelium of the urinary bladder of the toad reveals that the two major cell types which abut on the urinary surface, the granular and mitochondria-rich cells, also contact the basement membrane. Thus, the epithelium functions as a single cell layer. Although basal cells are interpolated between the granular cells and the basement membrane over a large portion of the epithelium, they do not constitute an additional continuous cell layer. This finding is consistent with extensive physiological data which had assumed that the major permeability barriers of this epithelium were the apical and basal-lateral plasma membranes of a single layer of cells. PMID:5782445

High-rate/high-temperature capability of a single-layer zicar-separator nickel-hydrogen cell

NASA Technical Reports Server (NTRS)

Wheeler, James R.

1995-01-01

A 50 Ampere-hour nickel-hydrogen cell with a single-layer Zircar separator stack design was fully charged and then discharged at a 2C current rate to an end voltage of 1 volt. This extreme test resulted in high temperatures which were recorded at three locations on the cell, i.e., the cell wall, the boss (barrel of the compression seal), and a terminal. The results provide new information about the high-temperature and high-discharge-rate capabilities of nickel-hydrogen cells. This information also adds to the growing data base for single-layer zirconium-oxide-cloth (Zircar) separator cell designs.

Physical criteria for the interface passivation layer in hydrogenated amorphous/crystalline silicon heterojunction solar cell

NASA Astrophysics Data System (ADS)

Zhao, Lei; Wang, Guanghong; Diao, Hongwei; Wang, Wenjing

2018-01-01

AFORS-HET (automat for simulation of heterostructures) simulation was utilized to explore the physical criteria for the passivation layer in hydrogenated amorphous/crystalline silicon heterojunction (SHJ) solar cells, by systematically investigating the solar cell current density-voltage (J-V) performance as a function of the interface defect density (D it) at the passivation layer/c-Si hetero-interface, the thickness (t) of the passivation layer, the bandgap (E g) of the passivation layer, and the density of dangling bond states (D db)/band tail states (D bt) in the band gap of the passivation layer. The corresponding impact regulations were presented clearly. Except for D it, the impacts of D db, D bt and E g are strongly dependent on the passivation layer thickness t. While t is smaller than 4-5 nm, the solar cell performance is less sensitive to the variation of D db, D bt and E g. Low D it at the a-Si:H/c-Si interface and small thickness t are the critical criteria for the passivation layer in such a case. However, if t has to be relatively larger, the microstructure, i.e. the material quality, including D db, D bt and E g, of the passivation layer should be controlled carefully. The mechanisms involved were analyzed and some applicable methods to prepare the passivation layer were proposed.

Process and design considerations for high-efficiency solar cells

NASA Technical Reports Server (NTRS)

Rohati, A.; Rai-Choudhury, P.

1985-01-01

This paper shows that oxide surface passivation coupled with optimum multilayer anti-reflective coating can provide approx. 3% (absolute) improvement in solar cell efficiency. Use of single-layer AR coating, without passivation, gives cell efficiencies in the range of 15 to 15.5% on high-quality, 4 ohm-cm as well as 0.1 to 0.2 ohm-cm float-zone silicon. Oxide surface passivation alone raises the cell efficiency to or = 17%. An optimum double-layer AR coating on oxide-passivated cells provides an additional approx. 5 to 10% improvement over a single-layer AR-coated cell, resulting in cell efficiencies in excess of 18%. Experimentally observed improvements are supported by model calculations and an approach to or = 20% efficient cells is discussed.

Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

NASA Technical Reports Server (NTRS)

Holloway, Nancy M. (Inventor); Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor); Leong, Kam W. (Inventor); Kulangara, Karina (Inventor)

2015-01-01

A scaffold assembly and related methods of manufacturing and/or using the scaffold for stem cell culture and tissue engineering applications are disclosed which at least partially mimic a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

Thermal phase transition behavior of lipid layers on a single human corneocyte cell.

PubMed

Imai, Tomohiro; Nakazawa, Hiromitsu; Kato, Satoru

2013-09-01

We have improved the selected area electron diffraction method to analyze the dynamic structural change in a single corneocyte cell non-invasively stripped off from human skin surface. The improved method made it possible to obtain reliable diffraction images to trace the structural change in the intercellular lipid layers on a single corneocyte cell during heating from 24°C to 100°C. Comparison of the results with those of synchrotron X-ray diffraction experiments on human stratum corneum sheets revealed that the intercellular lipid layers on a corneocyte cell exhibit essentially the same thermal phase transitions as those in a stratum corneum sheet. These results suggest that the structural features of the lipid layers are well preserved after the mechanical stripping of the corneocyte cell. Moreover, electron diffraction analyses of the thermal phase transition behaviors of the corneocyte cells that had the lipid layers with different distributions of orthorhombic and hexagonal domains at 24°C suggested that small orthorhombic domains interconnected with surrounding hexagonal domains transforms in a continuous manner into new hexagonal domains. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

NASA Technical Reports Server (NTRS)

Kulangara, Karina (Inventor); Scott Carnell, Lisa A. (Inventor); Holloway, Nancy M. (Inventor); Leong, Kam W. (Inventor); Siochi, Emilie J. (Inventor)

2017-01-01

A method of manufacturing and/or using a scaffold assembly for stem cell culture and tissue engineering applications is disclosed. The scaffold at least partially mimics a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation that uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

Organic electrochemical transistors for cell-based impedance sensing

NASA Astrophysics Data System (ADS)

Rivnay, Jonathan; Ramuz, Marc; Leleux, Pierre; Hama, Adel; Huerta, Miriam; Owens, Roisin M.

2015-01-01

Electrical impedance sensing of biological systems, especially cultured epithelial cell layers, is now a common technique to monitor cell motion, morphology, and cell layer/tissue integrity for high throughput toxicology screening. Existing methods to measure electrical impedance most often rely on a two electrode configuration, where low frequency signals are challenging to obtain for small devices and for tissues with high resistance, due to low current. Organic electrochemical transistors (OECTs) are conducting polymer-based devices, which have been shown to efficiently transduce and amplify low-level ionic fluxes in biological systems into electronic output signals. In this work, we combine OECT-based drain current measurements with simultaneous measurement of more traditional impedance sensing using the gate current to produce complex impedance traces, which show low error at both low and high frequencies. We apply this technique in vitro to a model epithelial tissue layer and show that the data can be fit to an equivalent circuit model yielding trans-epithelial resistance and cell layer capacitance values in agreement with literature. Importantly, the combined measurement allows for low biases across the cell layer, while still maintaining good broadband signal.

Proton exchange membrane micro fuel cells on 3D porous silicon gas diffusion layers

NASA Astrophysics Data System (ADS)

Kouassi, S.; Gautier, G.; Thery, J.; Desplobain, S.; Borella, M.; Ventura, L.; Laurent, J.-Y.

2012-10-01

Since the 90's, porous silicon has been studied and implemented in many devices, especially in MEMS technology. In this article, we present a new approach to build miniaturized proton exchange membrane micro-fuel cells using porous silicon as a hydrogen diffusion layer. In particular, we propose an innovative process to build micro fuel cells from a “corrugated iron like” 3D structured porous silicon substrates. This structure is able to increase up to 40% the cell area keeping a constant footprint on the silicon wafer. We propose here a process route to perform electrochemically 3D porous gas diffusion layers and to deposit fuel cell active layers on such substrates. The prototype peak power performance was measured to be 90 mW cm-2 in a “breathing configuration” at room temperature. These performances are less than expected if we compare with a reference 2D micro fuel cell. Actually, the active layer deposition processes are not fully optimized but this prototype demonstrates the feasibility of these 3D devices.

Stress Increases the Negative Effects of Chronic Pain on Hippocampal Neurogenesis.

PubMed

Romero-Grimaldi, Carmen; Berrocoso, Esther; Alba-Delgado, Cristina; Madrigal, Jose Luis M; Perez-Nievas, Beatriz G; Leza, Juan Carlos; Mico, Juan Antonio

2015-10-01

Patients with chronic pain often suffer from affective disorders and cognitive decline, which significantly impairs their quality of life. In addition, many of these patients also experience stress unrelated to their illness, which can aggravate their symptoms. These nociceptive inputs are received by the hippocampus, in which maladaptive neuroplastic changes may occur in the conditions of chronic pain. The hippocampus is a structure involved in emotionality, learning, and memory, and the proliferating cells in the granular layer of the hippocampal dentate gyrus respond to chronic pain by slowing their turnover. However, whether the maturation, survival, and integration of newborn cells in the hippocampus are affected by chronic pain remains unclear. In addition, it is unknown whether an added stress may increase this effect. We have evaluated the proliferation, differentiation, and survival of newborn hippocampal cells in a rat model of neuropathic pain (chronic constriction injury), with or without stress (chronic immobilization), by assessing the incorporation of bromodeoxyuridine into proliferating cells and immunostaining. The data obtained indicated that there was a decrease in the number of proliferating cells 8 days after nerve injury in animals subjected to neuropathic pain, an effect that was exacerbated by stress. Moreover, 4 weeks after nerve injury, neuropathic pain was associated with a loss of neuroblasts and the reduced survival of new mature neurons in the hippocampal granular layer, phenomena that also were increased by stress. By contrast, the rate of differentiation was not affected in this paradigm. Neuropathic pain negatively influences hippocampal neurogenesis (proliferation and survival), and this effect is exacerbated by stress. These neuroplastic changes may account for the affective and cognitive impairment seen in patients with chronic pain.

A direct main olfactory bulb projection to the ‘vomeronasal’ amygdala in female mice selectively responds to volatile pheromones from males

PubMed Central

Kang, Ningdong; Baum, Michael J.; Cherry, James A.

2009-01-01

The main olfactory system, like the accessory olfactory system, responds to pheromones involved in social communication. Whereas pheromones detected by the accessory system are transmitted to the hypothalamus via the medial (‘vomeronasal’) amygdala, the pathway by which pheromones are detected and transmitted by the main system is not well understood. We examined in female mice whether a direct projection from mitral/tufted (M/T) cells in the main olfactory bulb (MOB) to the medial amygdala exists, and whether medial amygdala-projecting M/T cells are activated by volatile urinary odors from conspecifics or a predator (cat). Simultaneous anterograde tracing using Phaseolus vulgaris leucoagglutinin and Fluoro-Ruby placed in the MOB and accessory olfactory bulb (AOB), respectively, revealed that axons of MOB M/T cells projected to superficial laminae of layer Ia in anterior and posterodorsal subdivisions of the medial amygdala, whereas projection neurons from the AOB sent axons to non-overlapping, deeper layer Ia laminae of the same subdivisions. Placement of the retrograde tracer cholera toxin B into the medial amygdala labeled M/T cells that were concentrated in the ventral MOB. Urinary volatiles from male mice, but not from female conspecifics or cat, induced Fos in medial amygdala-projecting MOB M/T cells of female subjects, suggesting that information about male odors is transmitted directly from the MOB to the ‘vomeronasal’ amygdala. The presence of a direct MOB-to-medial amygdala pathway in mice and other mammals could enable volatile, opposite-sex pheromones to gain privileged access to diencephalic structures that control mate recognition and reproduction. PMID:19187265

Laboratory flow experiments for visualizing carbon dioxide-induced, density-driven brine convection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kneafsey, T.; Pruess, K.

2009-09-01

Injection of carbon dioxide (CO{sub 2}) into saline aquifers confined by low-permeability cap rock will result in a layer of CO{sub 2} overlying the brine. Dissolution of CO{sub 2} into the brine increases the brine density, resulting in an unstable situation in which more-dense brine overlies less-dense brine. This gravitational instability could give rise to density-driven convection of the fluid, which is a favorable process of practical interest for CO{sub 2} storage security because it accelerates the transfer of buoyant CO{sub 2} into the aqueous phase, where it is no longer subject to an upward buoyant drive. Laboratory flow visualizationmore » tests in transparent Hele-Shaw cells have been performed to elucidate the processes and rates of this CO{sub 2} solute-driven convection (CSC). Upon introduction of CO{sub 2} into the system, a layer of CO{sub 2}-laden brine forms at the CO{sub 2}-water interface. Subsequently, small convective fingers form, which coalesce, broaden, and penetrate into the test cell. Images and time-series data of finger lengths and wavelengths are presented. Observed CO{sub 2} uptake of the convection system indicates that the CO{sub 2} dissolution rate is approximately constant for each test and is far greater than expected for a diffusion-only scenario. Numerical simulations of our system show good agreement with the experiments for onset time of convection and advancement of convective fingers. There are differences as well, the most prominent being the absence of cell-scale convection in the numerical simulations. This cell-scale convection observed in the experiments is probably initiated by a small temperature gradient induced by the cell illumination.« less

Effects of TiO2 electron blocking layer on photovoltaic performance of photo-electrochemical cell

NASA Astrophysics Data System (ADS)

Bin, Jae-Wook; Kim, Doo-Hwan; Sung, Youl-Moon; Park, Min-Woo

2014-06-01

Dye-sensitized solar cells (DSCs) have used transparent conductive Fluorine-doped SnO2 (FTO) glass/porous TiO2 layer attached using dye molecules/electrolytes (I-/I3-)/Platinium-coated FTO glass configuration. In this work, prior to the coating of nanoporous TiO2 layer on FTO glass, a dense layer of TiO2 film with a thickness of less than ∼100 nm was deposited directly onto the FTO as an electron blocking layer by radio frequency (RF) magnetron sputtering. Under 100 mW/cm2 illumination at AM 1.5, the energy conversion efficiency (η) of the prepared DSC with electron blocking layer of 80 nm thickness was 6.9% (Voc = 0.67 V, Jsc = 12.18 mA/cm2, ff = 0.63), which is increased by 1.3% compared to the typical cell without electron blocking layer.

Histomorphometry and expression of Cdc47 and caspase-3 in hyperthyroid rat uteri and placentas during gestation and postpartum associated with fetal development.

PubMed

Freitas, E S; Leite, E D; Souza, C A; Ocarino, N M; Ferreira, E; Cassali, G D; Gomes, M G; Serakides, R

2007-01-01

In two different experiments, the effects of hyperthyroidism on the histomorphometry and expression of Cdc47 and caspase-3 were evaluated in the uteri and placentas during gestation and postpartum. Fetal development was also evaluated during gestation. In the first experiment, 36 adult female Wistar rats were divided into two groups of 18 animals each: (1) hyperthyroid; and (2) euthyroid (control). Female rats were mated and killed at 7, 14 and 19 days of gestation. Uteri and placentas were weighed and subjected to histomorphometric and immunohistochemical evaluation to determine the expression of Cdc47 and caspase-3. Ovaries were also evaluated for weight and subjected to morphometric analysis. Fetuses were quantified and weighed individually. In the second experiment, 12 adult female Wistar rats were divided into two groups of six animals each: (1) hyperthyroid; and (2) euthyroid (control). Female rats were mated and killed 2 days postpartum. Uteri were evaluated in the same way as for the first experiment. Hyperthyroidism increased ovulation and conception rates without disturbing the size and viability of the fetuses. In the pregnant uteri, hyperthyroidism did not change the thickness of the layers or the expression of Cdc47 and caspase-3. However, in the placentas, hyperthyroidism increased the medium diameter of trophoblast cells, as well as the thickness and the expression of Cdc47 of spongiotrophoblast cells, at 14 days of gestation. During uterine involution, hyperthyroidism significantly increased the expression of Cdc47 and reduced the expression of caspase-3 in the uterine layers. In conclusion, hyperthyroidism increased the conception rate because of an ovulation gain, induced significant placental changes during pregnancy and, in the uterus, increased Cdc47 expression and decreased caspase-3 expression after parturition.

RE-PERG, a new procedure for electrophysiologic diagnosis of glaucoma that may improve PERG specificity.

PubMed

Mavilio, Alberto; Sisto, Dario; Ferreri, Paolo; Cardascia, Nicola; Alessio, Giovanni

2017-01-01

A significant variability of the second harmonic (2ndH) phase of steady-state pattern electroretinogram (SS-PERG) in intrasession retest has been recently described in glaucoma patients (GP), which has not been found in healthy subjects. To evaluate the reliability of phase variability in retest (a procedure called RE-PERG or REPERG) in the presence of cataract, which is known to affect standard PERG, we tested this procedure in GP, normal controls (NC), and cataract patients (CP). The procedure was performed on 50 GP, 35 NC, and 27 CP. All subjects were examined with RE-PERG and SS-PERG and also with spectral domain optical coherence tomography and standard automated perimetry. Standard deviation of phase and amplitude value of 2ndH were correlated by means of one-way analysis of variance and Pearson correlation, with the mean deviation and pattern standard deviation assessed by standard automated perimetry and retinal nerve fiber layer and the ganglion cell complex thickness assessed by spectral domain optical coherence tomography. Receiver operating characteristics were calculated in cohort populations with and without cataract. Standard deviation of phase of 2ndH was significantly higher in GP with respect to NC ( P <0.001) and CP ( P <0.001), and it correlated with retinal nerve fiber layer ( r =-0.5, P <0.001) and ganglion cell complex ( r =-0.6, P <0.001) defects in GP. Receiver operating characteristic evaluation showed higher specificity of RE-PERG (86.4%; area under the curve 0.93) with respect to SS-PERG (54.5%; area under the curve 0.68) in CP. RE-PERG may improve the specificity of SS-PERG in clinical practice in the discrimination of GP.

Self-Healing Laminate System

NASA Technical Reports Server (NTRS)

Keller, Michael W. (Inventor); White, Scott R. (Inventor); Beiermann, Brett A. (Inventor); Sottos, Nancy R. (Inventor)

2016-01-01

A laminate material may include a first flexible layer, and a self-healing composite layer in contact with the first flexible layer. The composite layer includes an elastomer matrix, a plurality of first capsules including a polymerizer, and a corresponding activator for the polymerizer. The laminate material may self-heal when subjected to a puncture or a tear.

Enhanced photovoltaic performances of graphene/Si solar cells by insertion of a MoS₂ thin film.

PubMed

Tsuboi, Yuka; Wang, Feijiu; Kozawa, Daichi; Funahashi, Kazuma; Mouri, Shinichiro; Miyauchi, Yuhei; Takenobu, Taishi; Matsuda, Kazunari

2015-09-14

Transition-metal dichalcogenides exhibit great potential as active materials in optoelectronic devices because of their characteristic band structure. Here, we demonstrated that the photovoltaic performances of graphene/Si Schottky junction solar cells were significantly improved by inserting a chemical vapor deposition (CVD)-grown, large MoS2 thin-film layer. This layer functions as an effective electron-blocking/hole-transporting layer. We also demonstrated that the photovoltaic properties are enhanced with the increasing number of graphene layers and the decreasing thickness of the MoS2 layer. A high photovoltaic conversion efficiency of 11.1% was achieved with the optimized trilayer-graphene/MoS2/n-Si solar cell.

Synergetic effect of double-step blocking layer for the perovskite solar cell

NASA Astrophysics Data System (ADS)

Kim, Jinhyun; Hwang, Taehyun; Lee, Sangheon; Lee, Byungho; Kim, Jaewon; Kim, Jaewook; Gil, Bumjin; Park, Byungwoo

2017-10-01

In an organometallic CH3NH3PbI3 (MAPbI3) perovskite solar cell, we have demonstrated a vastly compact TiO2 layer synthesized by double-step deposition, through a combination of sputter and solution deposition to minimize the electron-hole recombination and boost the power conversion efficiency. As a result, the double-step strategy allowed outstanding transmittance of blocking layer. Additionally, crystallinity and morphology of the perovskite film were significantly modified, provoking enhanced photon absorption and solar cell performance with the reduced recombination rate. Thereby, this straightforward double-step strategy for the blocking layer exhibited 12.31% conversion efficiency through morphological improvements of each layer.