Simulation of Panretinal Laser Photocoagulation Using Geometric Methods for Calculating the Photocoagulation Index

2016 ◽  
Vol 27 (2) ◽  
pp. 205-209 ◽  
Author(s):  
Kentaro Nishida ◽  
Hirokazu Sakaguchi ◽  
Motohiro Kamei ◽  
Nobuhiko Shiraki ◽  
Yoshihito Oura ◽  
...  
Keyword(s):  
Surface Area ◽  
Pulse Duration ◽  
Laser Photocoagulation ◽  
Curved Surface ◽  
Retinal Area ◽  
Spherical Dome ◽  
Geometric Methods ◽  
The Impact

Purpose To establish geometrically based methods for simulating panretinal laser photocoagulation (PRP) for the photocoagulation index. Methods A formula for calculating the curved surface area of a spherical dome was used for the simulation. If the radius of the dome is c and the height of the dome is h, then the curved surface area (S) of the dome is S = π (c2 + h2). We calculated the area of the whole retina using this formula and the anatomical dimensions of the standard eyeball. To simulate PRP with a 400-μm spot on the retina with 1-spot spacing, we drew 400-μm-diameter circles, separated by 400 μm, on a retinal map. We calculated the ratio of the total retinal photocoagulated area to the whole retina, termed the photocoagulation index, in order to investigate the impact of the extent of the photocoagulated area and the pulse duration on PRP. Results The whole retinal area was 1,092 mm2. The numbers of spots in the scattered and full-scattered PRP were 1,222 and 1,814, respectively. The photocoagulation index was 14.1% and 20.9% for scattered and full-scattered PRP, respectively. These values changed to 14.3% (5.6%) and 21.3% (8.3%), respectively, for PRP with a 100-ms pulse or a 20-ms pulse. Conclusions This method will be useful for investigating the impact of various PRP parameters (duration, spacing, intensity of burns, extent of photocoagulated area, etc.) on the photocoagulation index.

Evaluation of Nanotechniques and Conventional Techniques for the Removal of Dioxins

2018 ◽  
Vol 9 (1) ◽  
pp. 79-84
Author(s):  
Vaishali V. Shahare ◽  
Rajni Grover ◽  
Suman Meena
Keyword(s):  
Soil Sample ◽  
Human Health ◽  
Surface Area ◽  
Contaminated Soil ◽  
Conventional Treatment ◽  
Volume Ratio ◽  
Soil Samples ◽  
Dioxins And Furans ◽  
Palladized Iron ◽  
The Impact

Background: The persistent dioxins/furans has caused a worldwide concern as they influence the human health. Recent research indicates that nonmaterial may prove effective in the degradation of Dioxins/furans. The nanomaterials are very reactive owing to their large surface area to volume ratio and large number of reactive sites. However, nanotechnology applications face both the challenges and the opportunities to influence the area of environmental protection. Objective: i) To study the impact of oil mediated UV-irradiations on the removal of 2,3,7,8-TCDD, 2,3,7,8-TCDF, OCDD and OCDF in simulated soil samples. ii) To compare the conventional treatment methods with the modern available nanotechniques for the removal of selected Dioxins/furans from soil samples. Methods: The present work has investigated an opportunity of the degradation of tetra and octachlorinated dioxins and furans by using oil mediated UV radiations with subsequent extraction of respective dioxins/furans from soils. The results have been compared with the available nanotechniques. Results: The dioxin congeners in the simulated soil sample showed decrease in concentration with the increase in the exposure time and intensity of UV radiations. The dechlorination of PCDD/Fs using palladized iron has been found to be effective. Conclusion: Both the conventional methods and nanotechnology have a dramatic impact on the removal of Dioxins/furans in contaminated soil. However, the nanotechniques are comparatively costlier and despite the relatively high rates of PCDDs dechlorination by Pd/nFe, small fraction of the dioxins are recalcitrant to degradation over considerable exposure times.

scholarly journals Suitability of Bronchoscopic Biopsy Tissue Samples for Next-Generation Sequencing

Diagnostics ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 391
Author(s):  
Shuji Murakami ◽  
Tomoyuki Yokose ◽  
Daiji Nemoto ◽  
Masaki Suzuki ◽  
Ryou Usui ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Success Rate ◽  
Rna Sequencing ◽  
Surface Area ◽  
Endobronchial Ultrasound ◽  
Next Generation ◽  
Endobronchial Ultrasonography ◽  
Tissue Surface ◽  
The Impact ◽  
Generation Sequencing

A sufficiently large tissue sample is required to perform next-generation sequencing (NGS) with a high success rate, but the majority of patients with advanced non-small-cell lung cancer (NSCLC) are diagnosed with small biopsy specimens. Biopsy samples were collected from 184 patients with bronchoscopically diagnosed NSCLC. The tissue surface area, tumor cell count, and tumor content rate of each biopsy sample were evaluated. The impact of the cut-off criteria for the tissue surface area (≥1 mm2) and tumor content rate (≥30%) on the success rate of the Oncomine Dx Target Test (ODxTT) was evaluated. The mean tissue surface area of the transbronchial biopsies was 1.23 ± 0.85 mm2 when small endobronchial ultrasonography with a guide sheath (EBUS-GS) was used, 2.16 ± 1.49 mm2 with large EBUS-GS, and 1.81 ± 0.75 mm2 with endobronchial biopsy (EBB). The proportion of samples with a tissue surface area of ≥1 mm2 was 48.8% for small EBUS-GS, 79.2% for large EBUS-GS, and 78.6% for EBB. Sixty-nine patients underwent ODxTT. The success rate of DNA sequencing was 84.1% and that of RNA sequencing was 92.7% over all patients. The success rate of DNA (RNA) sequencing was 57.1% (71.4%) for small EBUS-GS (n = 14), 93.4% (96.9%) for large EBUS-GS (n = 32), 62.5% (100%) for EBB (n = 8), and 100% (100%) for endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) (n = 15). Regardless of the device used, a tissue surface area of ≥ 1 mm2 is adequate for samples to be tested with NGS.

scholarly journals Effect of Secondary Carbon Nanofillers on the Electrical, Thermal, and Mechanical Properties of Conductive Hybrid Composites Based on Epoxy Resin and Graphite

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4169
Author(s):  
Marcel Zambrzycki ◽  
Krystian Sokolowski ◽  
Maciej Gubernat ◽  
Aneta Fraczek-Szczypta
Keyword(s):  
Mechanical Properties ◽  
Specific Surface ◽  
Epoxy Resin ◽  
Surface Area ◽  
Specific Surface Area ◽  
Hybrid Composites ◽  
Department Of Energy ◽  
Carbon Nanofillers ◽  
The Impact ◽  
Secondary Carbon

In this work, we present a comparative study of the impact of secondary carbon nanofillers on the electrical and thermal conductivity, thermal stability, and mechanical properties of hybrid conductive polymer composites (CPC) based on high loadings of synthetic graphite and epoxy resin. Two different carbon nanofillers were chosen for the investigation—low-cost multi-layered graphene nanoplatelets (GN) and carbon black (CB), which were aimed at improving the overall performance of composites. The samples were obtained by a simple, inexpensive, and effective compression molding technique, and were investigated by the means of, i.a., scanning electron microscopy, Raman spectroscopy, electrical conductivity measurements, laser flash analysis, and thermogravimetry. The tests performed revealed that, due to the exceptional electronic transport properties of GN, its relatively low specific surface area, good aspect ratio, and nanometric sizes of particles, a notable improvement in the overall characteristics of the composites (best results for 4 wt % of GN; σ = 266.7 S cm−1; λ = 40.6 W mK−1; fl. strength = 40.1 MPa). In turn, the addition of CB resulted in a limited improvement in mechanical properties, and a deterioration in electrical and thermal properties, mainly due to the too high specific surface area of this nanofiller. The results obtained were compared with US Department of Energy recommendations regarding properties of materials for bipolar plates in fuel cells. As shown, the materials developed significantly exceed the recommended values of the majority of the most important parameters, indicating high potential application of the composites obtained.

Chemical EOR in Low Permeability Sandstone Reservoirs: Impact of Clay Content on the Transport of Polymer and Surfactant

2021 ◽  
Author(s):  
Imane Guetni ◽  
Claire Marlière ◽  
David Rousseau
Keyword(s):  
Porous Media ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Clay Content ◽  
Low Permeability ◽  
Depth Propagation ◽  
The Impact ◽  
Polymer Retention ◽  
Injection Strategies

Abstract Application of chemical enhanced oil recovery (C-EOR) processes to low-permeability sandstone reservoirs (in the 10-100 mD range) can be very challenging as strong retention and difficult in-depth propagation of polymer and surfactant can occur. Transport properties of C-EOR chemicals are particularly related to porous media mineralogy (clay content). The present experimental study aimed at identifying base mechanisms and providing general recommendations to design economically viable C-EOR injection strategies in low permeability clayey reservoirs. Polymer and surfactant injection corefloods were conducted using granular packs (quartz and clay mixtures) with similar petrophysical characteristics (permeability 70-130 mD) but having various mineralogical compositions (pure quartz sand, sand with 8 wt-% kaolinite and sand with 8 wt-% smectite). The granular packs were carefully characterized in terms of structure (SEM) and specific surface area (BET). The main observables from the coreflood tests were the resistance and residual resistance factors generated during the chemical injections, the irreversible polymer retention and the surfactant retention in various injection scenarios (polymer alone, surfactant alone, polymer and surfactant). A first, the impact of the clay contents on the retention of polymer and surfactant considered independently was examined. Coreflood results have shown that retention per unit mass of rock strongly increased in presence of both kaolinite and smectite, but not in the same way for both chemicals. For polymer, retention was about twice higher with kaolinite than with smectite, despite the fact that the measured specific surface area of the kaolinite was about 5 times less than that of the smectite. Conversely, for surfactant, retention was much higher with smectite than with kaolinite. Secondly, the impact of the presence of surfactant on the polymer in-depth propagation and retention was investigated in pure quartz and kaolinite-bearing porous media. In both mineralogies, the resistance factor quickly stabilized when polymer was injected alone whereas injection of larger solution volumes was required to reach stabilization when surfactant was present. In pure quartz, polymer retention was shown, surprisingly, to be one order of magnitude higher in presence of surfactant whereas with kaolinite, surfactant did not impact polymer retention. The results can be interpreted by considering adsorption-governed retention. The mechanistic pictures being that (a) large polymer macromolecules are not able to penetrate the porosity of smectite aggregates, whereas surfactant molecules can, and (b) that surfactant and polymer mixed adsorbed layers can be formed on surfaces with limited affinity for polymer. Overall, this study shows that C-EOR can be applied in low permeability reservoirs but that successful injection strategies will strongly depend on mineralogy.

scholarly journals The role of clay content and mineral surface area for soil organic carbon storage in an arable toposequence

2021 ◽  
Author(s):  
Steffen A. Schweizer ◽  
Carsten W. Mueller ◽  
Carmen Höschen ◽  
Pavel Ivanov ◽  
Ingrid Kögel-Knabner
Keyword(s):  
Organic Carbon ◽  
Surface Area ◽  
Agricultural Soils ◽  
Mineral Soil ◽  
Clay Content ◽  
Clay Soils ◽  
Mineral Surface ◽  
Mineral Surface Area ◽  
The Impact

AbstractCorrelations between organic carbon (OC) and fine mineral particles corroborate the important role of the abundance of soil minerals with reactive surfaces to bind and increase the persistence of organic matter (OM). The storage of OM broadly consists of particulate and mineral-associated forms. Correlative studies on the impact of fine mineral soil particles on OM storage mostly combined data from differing sites potentially confounded by other environmental factors. Here, we analyzed OM storage in a soil clay content gradient of 5–37% with similar farm management and mineral composition. Throughout the clay gradient, soils contained 14 mg OC g−1 on average in the bulk soil without showing any systematic increase. Density fractionation revealed that a greater proportion of OC was stored as occluded particulate OM in the high clay soils (18–37% clay). In low clay soils (5–18% clay), the fine mineral-associated fractions had up to two times higher OC contents than high clay soils. Specific surface area measurements revealed that more mineral-associated OM was related to higher OC loading. This suggests that there is a potentially thicker accrual of more OM at the same mineral surface area within fine fractions of the low clay soils. With increasing clay content, OM storage forms contained more particulate OC and mineral-associated OC with a lower surface loading. This implies that fine mineral-associated OC storage in the studied agricultural soils was driven by thicker accrual of OM and decoupled from clay content limitations.

scholarly journals Immobilization of Candida antarctica Lipase B on Silicone Nanofilaments

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Noah U. Naef ◽  
Stefan Seeger
Keyword(s):  
Surface Area ◽  
Candida Antarctica ◽  
Candida Antarctica Lipase B ◽  
High Signal ◽  
Candida Antarctica Lipase ◽  
Lipase B ◽  
Detection Systems ◽  
Novozyme 435 ◽  
The Impact ◽  
Enzyme Layer

Candida antarctica lipase B was immobilized on a series of silicone nanofilament-coated matrices of different porosities. In addition to creating a more open surface, SNF’s hydrophobicity allows for a simple immobilization pathway via adsorption. In order to study the impact of the nanostructure, the performance was compared with control samples lacking SNFs. For all materials, the surface was characterized with BET measurements, and the immobilized enzyme was measured as well as the catalytic activity. Enzyme loads ranged between 3.85% w / w and 2.53% w / w and decreased with the decreasing surface area of the carrier material from 200 m2/g to 0.04 m2/g, while the activity per enzyme increases from 824 U to 2040 U. The data suggest that the coating seals off inner surfaces, forcing the enzyme to be immobilized at more accessible positions allowing for higher activity per enzyme. Optimization of the immobilization conditions allowed us to create a thinner enzyme layer which further improved the activity per enzyme to 3129 U. While this activity is comparable to the commercial Novozyme 435 with 3073 U, the SNF-based system performs the catalysis in a thin surface layer of around 13 μm. A favorite area of application is, for example, the creation of enzyme-based detection systems, where the high activity per surface area of up to 89622 U · mg/m2 would lead to high signal strength.

scholarly journals The Effect of Sappanwood Absorbance on Design Decisions

2020 ◽  
pp. 34-42
Author(s):  
Dan Pandapotan ◽  
Imam Djati ◽  
Meirina Triharini ◽  
Yusuf Maulana
Keyword(s):  
Surface Area ◽  
Raw Materials ◽  
Health Benefits ◽  
Design Decisions ◽  
Measurement Results ◽  
Repeated Use ◽  
Product Thickness ◽  
The Impact ◽  
Material Cutting ◽  
Color Texture

Sappan wood contains substances that have health benefits. The community has made use of sappan wood in various forms, such as powder and shavings. In addition, sappan products are found in the form of blocks and spindles. If the product is in the form of blocks or logs, then people can recognize several characteristics of a wood, such as color, texture, hardness and weight. This will be more difficult to do if the product is in the form of powder or shavings. These advantages can be utilized in forms that have a specific purpose, such as the use function and decoration function. The use function can be done by soaking sappan wood using water, at a certain temperature and time. The process will produce a solution with a certain content which can be measured based on the absorbance value. The decoration function can be carried out by forming the sappan wood using the chisel principle, reducing the volume of raw materials. This research was conducted to determine the impact of shape on the concentration of content in sappan wood, so that it produces considerations that can be used in designing a product made from sappan wood. Experiments were carried out on 4 types of treatments, N specimens representing the treatment of repeated use, LPA and LPB specimens representing different surface area treatments, and specimens V representing treatments with different volumes. Each treatment produced a solution which was measured using UV-Vis Spectorphotometry. The measurement results in each specimen solution show the absorbance value can be taken into consideration in designing a product made from sappan wood. The things that need to be considered are the distance between cavities, product thickness and material cutting patterns.

scholarly journals Conversion of automotive paint sludge to activated carbon via microwave pyrolysis technique for supercapacitor application

2020 ◽  
Vol 3 (1) ◽  
pp. 35
Author(s):  
Siti Shawalliah Idris ◽  
Muhammad Nasrul Bojy ◽  
Zakiuddin Januri
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Power Supply ◽  
Pore Volume ◽  
Potassium Hydroxide ◽  
Microwave Pyrolysis ◽  
Supercapacitor Application ◽  
Paint Sludge ◽  
The Impact ◽  
Radiation Time

Conversion of waste to wealth has been one of the ways to reduce the volume of industrial waste to disposal site, hence reducing the impact to the environment. In this work, paint sludge from an automotive industry (APS) was converted into activated carbon through chemical activation (potassium hydroxide (KOH)) using microwave pyrolysis technique. The effect of power and radiation time on the produced activated carbon were investigated and characterised (carbon content, surface area, and pore volume) to identify the possibility of application as a supercapacitor. Potassium hydroxide activation of the APS char via microwave pyrolysis has shown that power level and radiation time has influenced the yield of the APS activated carbon. A longer radiation time and higher power supply has produced activated carbon having higher carbon contents, lower impurities, higher surface area and higher pore volume. Thus, the APS activated carbon obtained via microwave pyrolysis at power supply 1000 W and 45 minutes radiation time had produced the highest surface area and total pore volume of 434.3 m2/g and 0.2901 cm3/g, respectively. However, the produced activated carbon is not suitable for the supercapacitor application as the minimum surface area requirement must be more than 1000 m2/g. The pore size of the activated APS char produced in this study was in the range of mesopores size which was also considered very poor for supercapacitor application. The outcome of this research has shown that the produced activated carbon could otherwise be used for other application than a supercapacitor.

scholarly journals Ozone impacts of gas–aerosol uptake in global chemistry transport models

2018 ◽  
Vol 18 (5) ◽  
pp. 3147-3171 ◽  
Author(s):  
Scarlet Stadtler ◽  
David Simpson ◽  
Sabine Schröder ◽  
Domenico Taraborrelli ◽  
Andreas Bott ◽  
...  
Keyword(s):  
East Asia ◽  
Surface Area ◽  
General Circulation ◽  
Heterogeneous Reaction ◽  
Circulation Model ◽  
Photochemical Reactions ◽  
Heterogeneous Reactions ◽  
Transport Models ◽  
Global Pattern ◽  
The Impact

Abstract. The impact of six heterogeneous gas–aerosol uptake reactions on tropospheric ozone and nitrogen species was studied using two chemical transport models, the Meteorological Synthesizing Centre-West of the European Monitoring and Evaluation Programme (EMEP MSC-W) and the European Centre Hamburg general circulation model combined with versions of the Hamburg Aerosol Model and Model for Ozone and Related chemical Tracers (ECHAM-HAMMOZ). Species undergoing heterogeneous reactions in both models include N2O5, NO3, NO2, O3, HNO3, and HO2. Since heterogeneous reactions take place at the aerosol surface area, the modelled surface area density (Sa) of both models was compared to a satellite product retrieving the surface area. This comparison shows a good agreement in global pattern and especially the capability of both models to capture the extreme aerosol loadings in east Asia. The impact of the heterogeneous reactions was evaluated by the simulation of a reference run containing all heterogeneous reactions and several sensitivity runs. One reaction was turned off in each sensitivity run to compare it with the reference run. The analysis of the sensitivity runs confirms that the globally most important heterogeneous reaction is the one of N2O5. Nevertheless, NO2, HNO3, and HO2 heterogeneous reactions gain relevance particularly in east Asia due to the presence of high NOx concentrations and high Sa in the same region. The heterogeneous reaction of O3 itself on dust is of minor relevance compared to the other heterogeneous reactions. The impacts of the N2O5 reactions show strong seasonal variations, with the biggest impacts on O3 in springtime when photochemical reactions are active and N2O5 levels still high. Evaluation of the models with northern hemispheric ozone surface observations yields a better agreement of the models with observations in terms of concentration levels, variability, and temporal correlations at most sites when the heterogeneous reactions are incorporated. Our results are loosely consistent with results from earlier studies, although the magnitude of changes induced by N2O5 reaction is at the low end of estimates, which seems to fit a trend, whereby the more recent the study the lower the impacts of these reactions.

scholarly journals Analysis of isothermal and cooling rate dependent immersion freezing by a unifying stochastic ice nucleation model

2015 ◽  
Vol 15 (9) ◽  
pp. 13109-13166
Author(s):  
P. A. Alpert ◽  
D. A. Knopf
Keyword(s):  
Cooling Rate ◽  
Surface Area ◽  
Ice Nucleation ◽  
Rate Dependence ◽  
Nucleation Theory ◽  
Freezing Process ◽  
Nucleation Kinetics ◽  
Rate Dependent ◽  
Immersion Freezing ◽  
The Impact

Abstract. Immersion freezing is an important ice nucleation pathway involved in the formation of cirrus and mixed-phase clouds. Laboratory immersion freezing experiments are necessary to determine the range in temperature (T) and relative humidity (RH) at which ice nucleation occurs and to quantify the associated nucleation kinetics. Typically, isothermal (applying a constant temperature) and cooling rate dependent immersion freezing experiments are conducted. In these experiments it is usually assumed that the droplets containing ice nuclei (IN) all have the same IN surface area (ISA), however the validity of this assumption or the impact it may have on analysis and interpretation of the experimental data is rarely questioned. A stochastic immersion freezing model based on first principles of statistics is presented, which accounts for variable ISA per droplet and uses physically observable parameters including the total number of droplets (Ntot) and the heterogeneous ice nucleation rate coefficient, Jhet(T). This model is applied to address if (i) a time and ISA dependent stochastic immersion freezing process can explain laboratory immersion freezing data for different experimental methods and (ii) the assumption that all droplets contain identical ISA is a valid conjecture with subsequent consequences for analysis and interpretation of immersion freezing. The simple stochastic model can reproduce the observed time and surface area dependence in immersion freezing experiments for a variety of methods such as: droplets on a cold-stage exposed to air or surrounded by an oil matrix, wind and acoustically levitated droplets, droplets in a continuous flow diffusion chamber (CFDC), the Leipzig aerosol cloud interaction simulator (LACIS), and the aerosol interaction and dynamics in the atmosphere (AIDA) cloud chamber. Observed time dependent isothermal frozen fractions exhibiting non-exponential behavior with time can be readily explained by this model considering varying ISA. An apparent cooling rate dependence ofJhet is explained by assuming identical ISA in each droplet. When accounting for ISA variability, the cooling rate dependence of ice nucleation kinetics vanishes as expected from classical nucleation theory. The model simulations allow for a quantitative experimental uncertainty analysis for parameters Ntot, T, RH, and the ISA variability. In an idealized cloud parcel model applying variability in ISAs for each droplet, the model predicts enhanced immersion freezing temperatures and greater ice crystal production compared to a case when ISAs are uniform in each droplet. The implications of our results for experimental analysis and interpretation of the immersion freezing process are discussed.

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