Free convection heat transfer through coupled thermal boundary layers in a partitioned triangular enclosure

A numerical investigation has been carried out for the coupled thermal boundary layers on both sides of a partition placed in an isosceles triangular enclosure along its middle symmetric line. The working fluid is considered as air which is initially quiescent. A sudden temperature difference between two zones of the enclosure has been imposed to trigger the natural convection. It is anticipated from the numerical simulations that the coupled thermal boundary layers development adjacent to the partition undergoes three distinct stages; namely an initial stage, a transitional stage and a steady state stage. Time dependent features of the coupled thermal boundary layers as well as the overall natural convection flow in the partitioned enclosure have been discussed and compared with the non-partitioned enclosure. Moreover, heat transfer as a form of local and overall average Nusselt number through the coupled thermal boundary layers and the inclined walls is also examined. The details results will be discussed in the full paper.

Scaling analysis of natural convection boundary layers : Application to attic space

The natural convection thermal boundary layer adjacent to an inclined flat plate and inclined walls of an attic space subject to instantaneous and ramp heating and cooling is investigated. A scaling analysis has been performed to describe the flow behaviour and heat transfer. Major scales quantifying the flow velocity, flow development time, heat transfer and the thermal and viscous boundary layer thicknesses at different stages of the flow development are established. Scaling relations of heating-up and cooling-down times and heat transfer rates have also been reported for the case of attic space. The scaling relations have been verified by numerical simulations over a wide range of parameters. Further, a periodic temperature boundary condition is also considered to show the flow features in the attic space over diurnal cycles.

Precipitazioni sull'endotelio [Pigment Dispersion Syndrome]

Arguably, the most common patient seen in contact lens practice in our communities is the young adult white myope. The incidence of eye disease in this group of patients is very low, particularly if the genetically determined problems are excluded. However, there is one condition that should always be anticipated and searched for, especially in males. In fact, it affects 2-4% of these individuals and is known as pigment dispersion syndrome. This is important because 25-50% of these patients will get secondary or pigmentary glaucoma because of the pigment dispersion. It can be inherited as an autosomal dominant trait and has been mapped to chromosome 7. It is usually bilateral and is rarely encountered in patients of darker skin such as Asians and African-Americans.

No cure for curiosity: Linking physical and digital urban layers

Although mobile phones are often used in public urban places to interact with one’s geographically dispersed social circle, they can also facilitate interactions with people in the same public urban space. The PlaceTagz study investigates how physical artefacts in public urban places can be utilised and combined with mobile phone technologies to facilitate interactions. Printed on stickers, PlaceTagz are QR codes linking to a digital message board enabling collocated users to interact with each other over time resulting in a place-based digital memory. This exploratory project set out to investigate if and how PlaceTagz are used by urban dwellers in a real world deployment. We present findings from analysing content received through PlaceTagz and interview data from application users. QR codes, which do not contain any contextual information, piqued the curiosity of users wondering about the embedded link’s destination and provoked comments in regards to people, place and technology.

GABAergic modification of myopic and hyperopic ocular tissue effects on scleral fibroblast growth

Purpose: Myopia is a common eye disorder affecting up to 90% of children in South East Asia and 30% of the population worldwide. Myopia of high severity is a leading cause of blindness around the world (4th to 5th most common). Changes and remodelling of the sclera i.e. increase cellular proliferation & increase protein synthesis within scleral cells (↑ scleral DNA) and thinning and lose of extracellular matrix of sclera (↓ scleral GAG synthesis) have been linked to myopic eye growth in animal models. Signals acting on the sclera are thought to originate in the retina, and are modulated by the retinal pigment epithelium (RPE) with limited evidence suggesting that the RPE can modify scleral cell growth in culture. However, the mechanism of retinal signal transmission and the role of posterior eye cup tissue, including the RPE, in mediating changes in scleral fibroblast growth during myopia development are unclear. Retinal transmitter systems are critically involved in pathways regulating eye growth, which ultimately lead to alterations in the sclera if eye size is to change. A dopaminergic agonist and muscarinic antagonists decrease the proliferation of scleral chondrocytes when co-cultured with chick’s retinal pigment epithelium (RPE). GABA receptors have recently been localised to chick sclera. We therefore hypothesised that posterior eye cup tissue from myopic eyes would stimulate and from hyperopic eyes would inhibit growth of scleral fibroblasts in vitro and that GABAergic agents could directly interact with scleral cells or indirectly modify the effects of myopic and hyperopic posterior eye cup tissue on scleral fibroblast growth. Method: Fibroblastic cells obtained from 8-day-old chick sclera were used to establish cell banks. Two major experiments were performed. Experiment 1: To determine if posterior eye cup tissues from myopic eye stimulates and hyperopic eye inhibits scleral cell proliferation, when co-cultured with scleral cells in vitro. This study comprised two linked experiments, i) monocular visual treatments of FDM (form-deprivation myopia), LIM (lens-induced myopia) and LIH (lens-induced hyperopia) with assessment of the effect of full punch eye cup tissue on DNA and GAG synthesis by cultured chick scleral fibroblasts, and ii) binocular visual treatments comprising LIM and LIH with assessment of the effect of individual layers of eye cup tissues (neural retina, RPE and choroid) on cultured chick scleral fibroblasts. Visual treatment was applied for 3 days. Experiment 2: To determine the direct interaction of GABA agents on scleral cell growth and to establish whether GABA agents modify the stimulatory/inhibitory effect of myopic and hyperopic posterior eye cup tissues on cultured scleral cell growth in vitro. Two linked experiments were performed. i) GABA agonists (muscimol and baclofen) and GABA antagonists (bicuculine (-), CGP46381 and TPMPA) were added to scleral cell culture medium to determine their direct effect on scleral cells. ii) GABAergic agents (agonists and antagonists) were administered to scleral fibroblasts co-cultured with posterior eye cup tissue (retina, RPE, retina/RPE, RPE/choroid). Ocular tissues were obtained from chick eyes wearing +15D (LIH) or -15D lenses (LIM) for 3 days. In both experiments, tissues were added to hanging cell culture insert (pore size 1.0ìm) placed over each well of 24 well plates while scleral cells were cultured in DMEM/F12, Glutamax (Gibco) plus 10% FBS and penicillin/streptomycin (50U/ml)) and fungizone (1.25ug/ml) (Gibco), at seeding density of 30,000 cells/well at the bottom of the well and allowed to grow for 3 days. Scleral cells proliferation rate throughout the study was evaluated by determining GAG and DNA content of scleral cells using Dimethylmethylene blue (DMMB) dye and Quant-iTTm Pico Green® dsDNA reagent respectively. Results and analysis: Based on DNA and GAG content, there was no significant difference in tissue effect of LIM and LIH eyes on scleral fibroblast growth (DNA: 8.4 ± 1.1μg versus 9.3 ± 2.3 μg, p=0.23; GAG: 10.13 ± 1.4 μg versus 12.67 ± 1.2 μg, F2,23=6.16, p=0.0005) when tissues were obtained from monocularly treated chick eyes (FDM or +15D lens or -15D lens over right eyes with left eyes untreated) and co-cultured as full punch. When chick eyes were treated binocularly with -15D lens (LIM) right eye and +15D lens (LIH) left eyes and tissue layers were separated, the retina from LIM eyes did not stimulate scleral cell proliferation compared to LIH eyes (DNA: 27.2 ± 6.7 μg versus 23.2 ± 1.5 μg, p=0.23; GAG: 28.1 ±3.7 μg versus 28.7 ± 4.2 μg, p=0.21). Similarly, the LIH and LIM choroid did not produce a differential effect based on DNA (LIM 46.9 ± 6.4 μg versus LIH 53.5 ± 4.7 μg, p=0.18), however the choroid from LIH eyes induced higher scleral GAG content than from LIM eyes (32.5 ± 6.7 μg versus 18.9 ± 1.2 μg, p=0.023). In contrast, the RPE from LIM eyes caused a significant increase in fibroblast proliferation whereas the RPE from LIH eyes was relatively inhibitory (72.4 ± 6.3 μg versus 27.9 ± 2.3 μg, F1, 6=69.99, p=0.0005). GAG data were opposite to DNA data e.g. the RPE from LIH eyes increased (33.7 ± 7.9 μg) while the RPE from LIM eyes decreased (28.2 ± 3.0 μg) scleral cell growth (F1, 6=13.99, p=0.010). Based on DNA content, GABA agents had a small direct effect on scleral cell growth; GABA agonists increased (21.4 ± 1.0% and 18.3 ± 1.0% with muscimol and baclofen, p=0.0021), whereas GABA antagonists decreased fibroblast proliferation (-23.7 ± 0.9% with bicuculine & CGP46381 and -28.1 ± 0.5% with TPMPA, p=0.0004). GABA agents also modified the effect of LIM and LIH tissues (p=0.0005).The increase in proliferation rate of scleral fibroblasts co-cultured with tissues (RPE, retina, RPE/retina and RPE/choroid) from LIM treated eyes was enhanced by GABA agonists (muscimol: 27.4 ± 1.2%, 35.8 ± 1.6%, 8.4 ± 0.3% and 11.9 ± 0.6%; baclofen: 27.0 ± 1.0%, 15.8 ± 1.5%, 16.8 ± 1.2% and 15.4 ± 0.4%, p=0.014) whereas GABA antagonists further reduced scleral fibroblasts growth (bicuculine: -52.5 ± 2.5%, -36.9 ± 1.4%, -37.5 ± 0.6% and -53.7 ± 0.9%; TPMPA: 57.3 ± 1.3%, -15.7 ± 1.2%, -33.5 ± 0.4% and -45.9 ± 1.5%; CGP46381: -51.9 ± 1.6%, -28.5 ± 1.5%, -25.4 ± 2.0% and -45.5 ± 1.9% respectively, p=0.0034). GAG data were opposite to DNA data throughout the experiment e.g. GABA agonists further inhibited while antagonists relatively enhanced scleral fibroblasts growth for both LIM and LIH tissue co-culture. The effect of GABA agents was relatively lower (p=0.0004) for tissue from LIH versus LIM eyes but was in a similar direction. There was a significant drug effect on all four tissue types e.g. RPE, retina, RPE/retina and RPE/choroid for both LIM and LIH tissue co-culture (F20,92=3.928, p=0.0005). However, the effect of GABA agents was greatest in co-culture with RPE tissue (F18,36=4.865, p=0.0005). Summary and Conclusion: 1) Retinal defocus signals are transferred to RPE and choroid which then exert their modifying effect on scleral GAG and DNA synthesis either through growth stimulating factors or directly interacting with scleral cells in process of scleral remodeling during LIM and LIH visual conditions. 2) GABAergic agents affect the proliferation of scleral fibroblasts both directly and when co-cultured with ocular tissues in vitro.

Relationship among CFH and ARMS2 genotypes, macular pigment optical density, and neuroretinal function in persons without age-related macular degeneration

Purpose: To determine whether there is a difference in neuroretinal function and in macular pigment optical density between persons with high- and low-risk gene variants for age-related macular degeneration (AMD) and no ophthalmoscopic signs of AMD, and to compare the results on neuroretinal function to patients with manifest early AMD. Methods and Participants: Neuroretinal function was assessed with the multifocal electroretinogram (mfERG) for 32 participants (22 healthy persons with no AMD and 10 early AMD patients). The 22 healthy participants with no AMD had high- or low-risk genotypes for either CFH (rs380390) and/or ARMS2 (rs10490924). Trough-to-peak response densities and peak-implicit times were analyzed in 5 concentric rings. Macular pigment optical densitometry was assessed by customized heterochromatic flicker photometry. Results: Trough-to-peak response densities for concentric rings 1 to 3 were, on average, significantly greater in participants with high-risk genotypes than in participants with low-risk genotypes and in persons with early AMD after correction for age and smoking (p<0.05). The group peak- implicit times for ring 1 were, on average, delayed in the patients with early AMD compared with the participants with high- or low-risk genotypes, although these differences were not significant. There was no significant correlation between genotypes and macular pigment optical density. Conclusion: Increased neuroretinal activity in persons who carry high-risk AMD genotypes may be due to genetically determined subclinical inflammatory and/or histological changes in the retina. Neuroretinal function in healthy persons genetically susceptible to AMD may be a useful additional early biomarker (in combination with genetics) before there is clinical manifestation.

Utilization and optimization of a waste stream cellulose culture medium for pigment production by Penicillium spp

Aims This research sought to determine optimal corn waste stream–based fermentation medium C and N sources and incubation time to maximize pigment production by an indigenous Indonesian Penicillium spp., as well as to assess pigment pH stability. Methods and Results A Penicillium spp. was isolated from Indonesian soil, identified as Penicillium resticulosum, and used to test the effects of carbon and nitrogen type and concentrations, medium pH, incubation period and furfural on biomass and pigment yield (PY) in a waste corncob hydrolysate basal medium. Maximum red PY (497·03 ± 55·13 mg l−1) was obtained with a 21 : 1 C : N ratio, pH 5·5–6·0; yeast extract-, NH4NO3-, NaNO3-, MgSO4·7H2O-, xylose- or carboxymethylcellulose (CMC)-supplemented medium and 12 days (25°C, 60–70% relative humidity, dark) incubation. C source, C, N and furfural concentration, medium pH and incubation period all influenced biomass and PY. Pigment was pH 2–9 stable. Conclusions Penicillium resticulosum demonstrated microbial pH-stable-pigment production potential using a xylose or CMC and N source, supplemented waste stream cellulose culture medium. Significance and Impact of the Study Corn derived, waste stream cellulose can be used as a culture medium for fungal pigment production. Such application provides a process for agricultural waste stream resource reuse for production of compounds in increasing demand.

The cultivation of human retinal pigment epithelial cells on Bombyx mori silk fibroin

We have presently evaluated membranes prepared from Bombyx mori silk fibroin (BMSF), for their potential use as a prosthetic Bruch’s membrane and carrier substrate for human retinal pigment epithelial (RPE) cell transplantation. Porous BMSF membranes measuring 3 μm in thickness were prepared from aqueous solutions (3% w/v) containing poly(ethylene oxide) (0.09%). The permeability coefficient for membranes was between 3 and 9 × 10-5 cm/s by using Allura red or 70 kDa FITC-dextran respectively. Average pore size (± sd) was 4.9 ± 2.3 µm and 2.9 ± 1.5 µm for upper and lower membrane surfaces respectively. Optimal attachment of ARPE-19 cells to BMSF membrane was achieved by pre-coating with vitronectin (1 µg/mL). ARPE-19 cultures maintained in low serum on BMSF membranes for approximately 8 weeks, developed a cobble-stoned morphology accompanied by a cortical distribution of F-actin and ZO-1. Similar results were obtained using primary cultures of human RPE cells, but cultures took noticeably longer to establish on BMSF compared with tissue culture plastic. These findings encourage further studies of BMSF as a substrate for RPE cell transplantation.

Hybrid place : blurring the edge between the digital and physical layers of urban environments

The purpose of this paper is to investigate the edge condition between the digital layers and the physical layers of the city and how tangible expressions of the interrelationships between them to create and define new experiences of place, creating hybrid place. To date there has been discussion and investigation into understanding the importance of place, similarly into defining hybrid space. This paper explores principles of place and space to question how they can be applied into defining and proposing the notion of hybrid place in urban environments. The integration of media spaces into architecture provide infrastructure for the development of hybrid place. The physical boundaries of urban spaces become blurred through the integration of media such as computer technologies connecting the physical environment with the digital. Literature and case studies that reflect the current trends of use of technology by people in space and place within urban environments are examined.

Effectiveness of cysteine proteases on protein/pigment film removal

Objective: Theaflavin (TF) from the black tea can react to human salivary proline-rich proteins (PRPs) to form stains on exposed dental surfaces. Here, we employed a model of protein/pigment film using TF and dephosphorylated bovine b-casein (Db-CN), which has an extended conformation, similar to that of salivary PRPs, on a sensor surface to assess the efficacy of cysteine proteases (CPs) including papain, stem bromelain, and ficin, on removing TF bound to Db-CN and the control TF readsorption on the residual substrate surfaces was also measured. Methods: The protein/pigment complex film was built by using a quartz crystal microbalance with dissipation (QCM-D). The efficacies of CPs were assessed by Boltzman equation model. The surface details were detected by grazing angle infrared spectroscopy spectra, atomic force microscopy images, and contact angles. Results: The efficacy order of CPs on hydrolyzing protein/pigment complex film is ficin > papain > bromelain. The results from grazing angle infrared spectroscopy spectra, atomic force microscopy images, and contact angles demonstrated that TF bound on the Db- CN was effectively removed by the CPs, and the amount of TF readsorption on both the residual film of the Db-CN/TF and the Db-CN was markedly decreased after hydrolysis. Conclusion: This study indicates the potential application of the CPs for tooth stain removal and suggests that these enzymes are worthy of further investigation for use in oral healthcare.

Unsteady buoyancy driven flows and heat transfer through coupled thermal boundary layers in a partitioned triangular enclosure

A numerical investigation has been carried out for the coupled thermal boundary layers on both sides of a partition placed in an isosceles triangular enclosure along its middle symmetric line. The working fluid is considered as air which is initially quiescent. A sudden temperature difference between two zones of the enclosure has been imposed to trigger the natural convection. It is anticipated from the numerical simulations that the coupled thermal boundary layers development adjacent to the partition undergoes three distinct stages; namely an initial stage, a transitional stage and a steady state stage. Time dependent features of the coupled thermal boundary layers as well as the overall natural convection flow in the partitioned enclosure have been discussed and compared with the non-partitioned enclosure. Moreover, heat transfer as a form of local and overall average Nusselt number through the coupled thermal boundary layers and the inclined walls is also examined.

Evolution of epitaxial graphene layers on 3C SiC/Si (111) as a function of annealing temperature in UHV

The growth of graphene on SiC/Si substrates is an appealing alternative to the growth on bulk SiC for cost reduction and to better integrate the material with Si based electronic devices. In this paper, we present a complete in-situ study of the growth of epitaxial graphene on 3C SiC (111)/Si (111) substrates via high temperature annealing (ranging from 1125˚C to 1375˚C) in ultra high vacuum (UHV). The quality and number of graphene layers have been thoroughly investigated by using x-ray photoelectron spectroscopy (XPS), while the surface characterization have been studied by scanning tunnelling microscopy (STM). Ex-situ Raman spectroscopy measurements confirm our findings, which demonstrate the exponential dependence of the number of graphene layer from the annealing temperature.

Tensile properties of Si nanowires with faulted stacking layers

Semiconductor nanowires (NWs) show tremendous applications in micro/nano-electro-mechanical systems. In order to fulfill their promising applications, an understanding of the mechanical properties of NWs becomes increasingly important. Based on the large-scale molecular dynamics simulations, this work investigated the tensile properties of Si NWs with different faulted stacking layers. Different faulted stacking layers were introduced around the centre of the NW by the insertion or removal of certain stacking layers, inducing twins, intrinsic stacking fault, extrinsic stacking fault, and 9R crystal structure. Stress–strain curves obtained from the tensile deformation tests reveal that the presence of faulted stacking layers has induced a considerable decrease to the yield strength while only a minor decrease to Young's modulus. The brittle fracture phenomenon is observed for all tested NWs. In particular, the formation of a monatomic chain is observed for the perfect NW, which exists for a relatively wide strain range. For the defected NW, the monatomic chain appears and lasts shorter. Additionally, all defected NWs show a fracture area near the two ends, in contrast to the perfect NW whose fracture area is adjacent to the middle. This study provides a better understanding of the mechanical properties of Si NWs with the presence of different faulted stacking layers.

Identification of GABA receptors in chick retinal pigment epithelium

Purpose: The retinal pigment epithelium (RPE) is a multifunctional, monolayer of cells located between the neural retina and the choroicapillaris. γ-Aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the retina and GABA receptors are known to be present in chick retina, sclera and cornea. There is a report of genes involved in GABA receptor signaling being expressed in human RPE, however, whether GABA receptors are present in chick RPE is unknown. Methods: Real time PCR and western blot were used to determine the expression of GABA receptors (alpha1 GABAA, GABABR2, and rho1 GABAC receptors) in isolated chicken RPE. Immunofluorescence using antibodies against one of the GABA receptor sub-types was used to determine receptor localization. Results: Both real-time PCR and western blot demonstrated that alpha1 GABAA, GABABR2 and rho1 GABAC receptors were expressed in isolated chick RPE. Immunofluorescence further demonstrated that GABA receptors were localized to the cell membrane and plasma of RPE cells. Conclusions: Alpha1 GABAA, GABABR2 and rho1 GABAC receptors were expressed in chick RPE. The purpose of the GABA receptors within the RPE remains to be explored.