Topography Properties Research Articles

Оценка изменения биомеханических свойств роговицы при кератэктазиях

Purpose. To make a comparative analysis of topographic, tomographic and biomechanical values, measured by Pentacam HR and Corvis ST, in healthy multirefractive cohort versus patients with keratectasia of various severity. Material and methods. The prospective study comprised 237 patients aged from 18 to 47 years, subdivided into three groups. The first group included 174 healthy persons with various refraction (174 eyes). The second and the third group embraced 63 patients with keratoconus: 36 patients (36 eyes) with keratoconus of the I degree and 27 eyes with keratoconus of the II and III degrees. Besides the conventional comprehensive ocular examination the following studies were performed in all the patients: evaluation of topographic, tomographic and biomechanical corneal properties with application of Pentacam HR and Corvis ST (OCULUS Optikgerate GmbH; Wetzlar, Germany). Results. It was revealed that the following biomechanical values, assessed by means of Pentacam HR and Corvis ST, exhibited statistically significant changes (p<0,001) in all degrees of ketatoconus: a relative corneal thickness by Ambrosio, inverted radius of applanation curvature (IntRadius), DA Ratio Coefficient, values of corneal rigidity – SP-A 1 and SSI. Conclusion. The detected parameters may be applied as indicators, allowing to evaluate corneal biomechanics, to define early features of ectatic process, to assess effectiveness of the performed corneal collagen crosslinking and intralamellar keratoplasty with implantation of corneal segments. Key words: keratoconus, corneal biomechanics, pachymetry, index of pachymetric progression, corneal viscoelasticity.

Nutritionally induced nanoscale variations in spider silk structural and mechanical properties

Spider major ampullate (MA) silk is characterized by high strength and toughness and is adaptable across environments. Experiments depriving spiders of protein have enabled researchers to examine nutritionally induced changes in gene expression, protein structures, and bulk properties of MA silk. However, it has not been elucidated if it varies in a similar way at a nanoscale. Here we used Atomic Force Microscopy (AFM) to simultaneously examine the topographic, structural, and mechanical properties of silks spun by two species of spider, Argiope keyserlingi and Latrodectus hasselti, at a nanoscale when protein fed or deprived. We found height, a measure of localized width, to substantially vary across species and treatments. We also found that Young's modulus, which may be used as an estimate of localized stiffness, decreased with protein deprivation in both species' silk. Our results suggest that nanoscale skin-core structures of A. keyserlingi's MA silk varied significantly across treatments, whereas only slight structural and functional variability was found for L. hasselti's silk. These results largely agreed with examinations of the bulk properties of each species' silk. However, we could not directly attribute the decoupling between protein structures and bulk mechanics in L. hasselti's silk to nanoscale features. Our results advance the understanding of processes inducing skin and core structural variations in spider silks at a nanoscale, which serves to enhance the prospect of developing biomimetic engineering programs.

Change Detection Using a Texture Feature Space Outlier Index from Mono-Temporal Remote Sensing Images and Vector Data

Multi-temporal remote sensing images are the primary sources for change detection. However, it is difficult to obtain comparable multi-temporal images at the same season and time of day with the same sensor. Considering texture homogeneity among objects belonging to the same category, this paper presents a new change detection approach using a texture feature space outlier index from mono-temporal remote sensing images and vector data. In the proposed approach, a texture feature contribution index (TFCI) is defined based on information gain to select the optimal texture features, and a feature space outlier index (FSOI) based on local reachability density is presented to automatically identify outlier samples and changed objects. Our approach includes three steps: (1) the sampling method is designed considering spatial distribution and topographic properties of image objects extracted by segmenting the recent image with existing vector map. (2) Samples with changed categories are refined by an iteration procedure of texture feature selection and outlier sample elimination; and (3) the changed image objects are identified and classified using the refined samples to calculate the FSOI values of the image objects. Three experiments in the two study areas were conducted to validate its performance. Overall accuracies of 95.94%, 96.36%, and 96.28% were achieved, respectively, while the omission and commission errors for every category were all very low. Four widely used methods with two-temporal images were selected for comparison, and the accuracy of the proposed method is higher than theirs. This indicates that our approach is effective and feasible.

The diameter factor of aligned membranes facilitates wound healing by promoting epithelialization in an immune way

Topographical properties, such as pattern and diameter, of biomaterials play important roles in influencing cell activities and manipulating the related immune response during wound healing. We prepared aligned electrospinning membranes with different fiber diameters, including 319 ± 100 nm (A300), 588 ± 132 nm (A600), and 1048 ± 130 nm (A1000), by adjusting the distance from the tip to the collector, the injection rate, and the concentration of the solution. The A300 membranes significantly improved cell proliferation and spreading and facilitated wound healing (epithelization and vascularization) with the regeneration of immature hair follicles compared to the other membranes. Transcriptomics revealed the underlying molecular mechanism that A300 could promote immune-related processes towards a pro-healing direction, significantly promoting keratinocyte migration and skin wound healing. All the results indicated that wound healing requires the active participation of the immune process, and that A300 was a potential candidate for guided skin regeneration applications.

Inclusion of Narrow Flow Paths between Buildings in Coarser Grids for Urban Flood Modeling: Virtual Surface Links

Urban flood modeling benefits from new remote sensing technologies, which provide high-resolution data and allow the consideration of small-scale urban key features. Since high-resolution data often result in large simulation runtimes, coarsening of the 2D grid via resampling techniques can be used to achieve a good balance between accuracy and computation time. However, the representation of urban features and topographical properties degrades, since small-scale features are blurred. Therefore, narrow flow paths between buildings are often not considered, building’s sizes are overestimated, and their arrangement in the grid changes. Thus, flow paths change and waterways are blocked, leading to incorrect inundations around buildings. This paper develops a method to improve the simulation results of coarser grids by adding virtual surface links (VSL) between buildings. The VSL mimic the flow paths of a high-resolution model in the areas of interest. The approach is developed for dual-drainage 1D/2D models. The approach shows a visible improvement at the localized level where the VSL are applied, in terms of under/overestimating flooding and a moderate overall improvement of the simulation results. Relatively to the model resolution of 2 m, the computational time, by applying this method, is reduced by 93.6% when using a 5 m grid and by 99% when using a 10 m grid. For a small test case, where the local effects are investigated, the error in the maximum water volume, relative to a grid size of 2 m, is reduced from 69.63% to 5.03% by using a 5 m grid and from 152.75% to 22.92% for a 10 m grid.

Guiding cell adhesion and motility by modulating cross-linking and topographic properties of microgel arrays.

Biomaterial-driven modulation of cell adhesion and migration is a challenging aspect of tissue engineering. Here, we investigated the impact of surface-bound microgel arrays with variable geometry and adjustable cross-linking properties on cell adhesion and migration. We show that cell migration is inversely correlated with microgel array spacing, whereas directionality increases as array spacing increases. Focal adhesion dynamics is also modulated by microgel topography resulting in less dynamic focal adhesions on surface-bound microgels. Microgels also modulate the motility and adhesion of Sertoli cells used as a model for cell migration and adhesion. Both focal adhesion dynamics and speed are reduced on microgels. Interestingly, Gas2L1, a component of the cytoskeleton that mediates the interaction between microtubules and microfilaments, is dispensable for the regulation of cell adhesion and migration on microgels. Finally, increasing microgel cross-linking causes a clear reduction of focal adhesion turnover in Sertoli cells. These findings not only show that spacing and rigidity of surface-grafted microgels arrays can be effectively used to modulate cell adhesion and motility of diverse cellular systems, but they also form the basis for future developments in the fields of medicine and tissue engineering.

Plasma-assisted multiscale topographic scaffolds for soft and hard tissue regeneration

The design of transplantable scaffolds for tissue regeneration requires gaining precise control of topographical properties. Here, we propose a methodology to fabricate hierarchical multiscale scaffolds with controlled hydrophilic and hydrophobic properties by employing capillary force lithography in combination with plasma modification. Using our method, we fabricated biodegradable biomaterial (i.e., polycaprolactone (PCL))-based nitrogen gas (N-FN) and oxygen gas plasma-assisted flexible multiscale nanotopographic (O-FMN) patches with natural extracellular matrix-like hierarchical structures along with flexible and controlled hydrophilic properties. In response to multiscale nanotopographic and chemically modified surface cues, the proliferation and osteogenic mineralization of cells were significantly promoted. Furthermore, the O-FMN patch enhanced regeneration of the mineralized fibrocartilage tissue of the tendon–bone interface and the calvarial bone tissue in vivo in rat models. Overall, the PCL-based O-FMN patches could accelerate soft- and hard-tissue regeneration. Thus, our proposed methodology was confirmed as an efficient approach for the design and manipulation of scaffolds having a multiscale topography with controlled hydrophilic property.

Assessing land suitability for rainfed paddy rice production in Zambia

Rice is one of the staple food crops and is a profitable smallholder cash crop in Zambia. It has the potential to contribute significantly to increased incomes and employment among rural producers. However, rice is the only staple crop in the country for which domestic production does not meet or exceed domestic demand. Low productivity is one of the factors that contribute to this. One necessary step towards addressing this problem is the identification of land with greatest potential for rice production, as well as the identification of land-based limitations which might be overcome by improved management. The aim of this study was to develop a land suitability index for rainfed paddy rice production reflecting expert opinion and published studies based on climatic, topographic and soil properties. Land suitability was evaluated using a method which accounts for important multiple factors, and which considers their joint effect in terms of a hierarchical model of constraints. The suitability classes were ranked according to the FAO land suitability classification as: Highly Suitable (S1), Moderately Suitable (S2), Marginally Suitable (S3), Currently Not Suitable (N2), and Permanently Not Suitable (N1). Results showed that there is limited potential for rainfed paddy rice production in Zambia with <20% of the land classified as either highly or moderately suitable. Therefore, the potential of irrigated and upland rice production in Zambia needs to be assessed as this would help expand the potential production area of rice.

Fabrication and Characterization of Gold Nanoparticles by Electrolysis Technique for schottky photodiode applications

In this research gold nano-particles (AuNPs) was synthesized by electrolysis Technique. Au thin films were deposited on the silicon and the borosilicate glass at a Temperature (80 °C) by dropcasting method. Structural, optical and topographic properties of prepared Au NPs was estimated by UV-VIS spectrometer, TEM, AFM, and XRD diffraction. The open circuit Voltage (Voc=2.8 mV) and Short-circuit density (Isc=5mA). This resultant relive that the fill factor (F.F) and conversation efficiency (η), were 32% and 9.3% respectively.

Study of the effect of temperature on optical and topographical properties of RF ‎Magnetron Sputtered ZrO2 thin films‎

In this paper, ZrO2 thin films were grown on glass substrates using RF magnetic sputtering method. In ‎three separate experiments, three samples of ZrO2 film were prepared at various temperatures. Three ‎temperatures of 25 ̊C (laboratory temperature), 150 ̊C and 250 ̊C were selected for three samples, respectively. Except for temperature, other parameters ‎such as pressure, film growth rate, substrate to target distance and deposition time were the same for all ‎three samples. Optical properties and morphology of the samples were investigated. The morphology of ‎the samples was determined by atomic force microscopy (AFM) images and the ‎transmittance was measured using optical spectroscopy. The optical constants of the films were also ‎calculated using their spectrum. The results show that the effect of temperature is especially evident on ‎the optical properties of the films. As the temperature increases from the ambient temperature to ‎‎250 ̊C, the refractive index changes from n = 2.11 to n = 2.18. Moreover, increasing the ‎temperature, causes the absorption of the layer to increase. The morphology of the films also changes slightly ‎by changing temperature. The average roughness of all three samples is less than half a nanometer.‎.‎‎

Soil microbial activity along an altitudinal gradient: Vegetation as a main driver beyond topographic and edaphic factors

An altitudinal gradient in the mountains constitutes a unique ‘open-lab’ to examine environmental hypotheses and analyse the expected effects of global warming. The distribution of carbon (C)-, nitrogen (N)-, and phosphorus (P)-acquiring enzyme activity, microbial catabolic activity as represented by a community-level physiological profile (CLPP), and microbial functional diversity (HCLPP) within mountainous ecosystems consisting of mixed, fir and deciduous forests, as well as subalpine and alpine meadows (1260–2480 m a.s.l., Mt. Tkachiha, the Northwest Caucasus, Russia) has been studied. Concerning potential drivers, vegetation (plant projective cover, plant functional group composition, plant richness and diversity) and edaphic (soil nutrients: total and available C and N, total P, pH, texture, temperature, microbial biomass C) and topographic (elevation, slope, mean annual temperature calculated using biannual monitoring data) properties have been considered. The distribution patterns of the studied hydrolytic enzymes along an altitudinal gradient cannot be explained solely by elevation change and soil nutrient content. The activity of soil leucine aminopeptidase depends on vegetation type and graminoid abundance. β-D-glucosidase activity was mainly driven by the quality of soil organic matter (SOM), demonstrating a significant relation with the soil C:N ratio. The chitinase and phosphatase turned out soil temperature-sensitive enzymes. The CLPP depends on the available N content in the soil. The HCLPP distribution with altitude was driven by available N and forbs abundance represented by the widest spectrum of plant families and species. An altitudinal gradient determines the spread of the vegetation zone. In turn, vegetation properties, such as plant functional group composition, species richness and diversity, play a significant role in the distribution of soil microbial activity along an altitudinal gradient that controls the decomposition of SOM and nutrient cycling. Thus, the significant role of vegetation in the distribution of soil microbial activity across a wide range of natural ecosystems and in consideration of topographic and edaphic factors has been demonstrated.

SPECIFIC CORNEAL PARAMETERS AND VISUAL ACUITY CHANGES AFTER CORNEAL CROSSLINKING TREATMENT FOR PROGRESSIVE KERATOCONUS.

To evaluate the effect of crosslinking (CXL) therapy on the change in the quality of visual acuity and the change in the topographic properties of the cornea - curvature, pachymetry, and change of astigmatism, coma abberation and CLMIaa (Cone Localisation and Magnitude Index). Aretrospective analytical study included 29 eyes of 24 patients who had progressed in the last 12 months and were suitable candidates for CXL surgery. The monitored parameters were the steepest, flatest and mean anterior instantaneous curvature (AICS, AICF, AICM) and the steepest, flatest and mean posterior instantaneous curvature (PICS, PICF, PICM) of the cornea, corneal thickness in the centre of the cornea (PACHC) and in the thinnest point of the cornea (PACHT), corneal astigmatism (ASTIG). coma (COMA), Cone Localization and Magnitude Index (CLMIaa) and uncorrected distance visual acuity (UDVA) with corrected distance visual acuity (CDVA). Data were analysed before surgery and 12 months after surgery. The AIC, COMA, CLMIaa and ASTIG parameters were analysed by paired t test. As the parameters of UDVA, CDVA, PIC and PACH did not meet the conditions of normal distribution, the Wilcoxon test was used to investigate the change in these parameters after CXL. Twelve months after the procedure, we recorded an improvement in UDVA (p=0.371) and CDVA (p=0.825), an increase in PICS, PICF and PICM (p=0.902; p=0.87 and p=0.555), adecrease in PACHCC (p=0.294) and adecrease in CLMIaa (p=0.113) that did not reach statistical significance. The decrease in PACHT (p=0.027), decrease in COMA (p=0.037) and decrease in anterior corneal curvature of AICS, AICF and AICM were statistically significant (p=0.019; p=0.010 and p=0.005). The decrease in the value of astigmatism did not show statistical significance, as p=0.297. CXL corneal therapy has been shown to be an effective method to stabilize the cornea in progressive keratoconus, and to improve the higher order of coma. This contributes to the possible improvement of UDVA and CDVA.

Study of Topographical Properties of CuO thin film prepared by CBD method at various deposition times

In this study, thin films of copper oxide (CuO) prepared using a chemical bath deposition (CBD) method on glass substrate. Aqueous copper sulfate (CuSo4.5H2O) used to obtain the required thin films and in concentration 0.1M. The films prepared during different deposition times (1, 4 and 8) days at room temperature. The XRD studies showed that the thin film prepared at deposition time (8 days) has polycrystalline structure (monoclinic structure). Morphological studies by using AFM measurements and topographical studies by using SEM measurements revealed that the surfaces of the prepared thin films show better uniformity when increasing deposition time from 1 day to 8 days, where the average diameter, roughness rate and root mean square (RMS) decreased with increasing deposition time

Effect of mixed ZnO/CuO nanoparticles on the structural, morphological, and topographical properties

In the present work, pure and composite ZnO/CuO were effectively deposited by chemical spray pyrolysis. Structural, morphological, and topographical features have been well investigated and explained. XRD analysis showed a polycrystalline structure with hexagonal and monoclinic systems for ZnO and CuO, respectively. The crystal size that calculated from XRD patterns has decreased with the increase of CuO content, while the dislocation density and the micro strain have increased. These results lead to high defects in the structure of the nanocomposite which will be more efficient in a specific application. Moreover, the morphology of the samples was examined by FESEM and it was spherical-like shapes and has elevated points, whereas the EDX confirm the existence of the employed materials without any other undesired materials. The topography of the surface depicted a slightly rough surface which will be suitable for different nanoelectronics devices.

Controllable synthesization of Au nanoparticles by laser enhanced wet KOH etching process

In Si substrate, anisotropic KOH etchants are mainly utilized to form pyramids like on the Si surface . However, this process is not well controlled way owing to the different and random etching pathway. In this work, we applied laser radiation during the anisotropic KOH wet etching process to modifies the topographical properties of Si substrate, as an efficient,simple and low cost texturing process for Si substrate. This approach employs different laser wavelength to modify the topographical features from a crater like structures to Si nanocrystallites in the form of pillars like structures on the Si surface. In order to investigate the formation of plasmonics species, gold nanoparticles was incorporated into Si surfaces by simple ion reduction process. The Si topographical features was studied with atomic scanning microscopy (AFM) images of Si before and after laser irradiation process. The irradiation with 405 laser wavelength, show the formation of thin and high density of Si nano pillars-like structures compared with more thick depther Si nano pillars like structures layer.

Analyzing Inundation Impacts on Transportation Network - The Case Study of Vadodara City

Inundation and related problems have become more uncontrollable all over the world leading to unexpected deaths, severe damage to infrastructure, and epidemics like conditions every year. A great number of cities in India have reported a series of heavy hazardous precipitation events during past few years. The immediate effects observed of floods specifically in urban areas are on the transportation network leading to its disruption. Most of the studies on transportation susceptibility including immediate and shortly after inundation events consider topographic properties along with supply and demand side of transportation system to access the disruption caused. In response to such events, this study aims to provide framework to access the susceptibility to urban road network due to inundation events. An integrated framework between meteorological information, land use functions, and hydrodynamic model simulated in HEC-RAS with rainfall event with 1-in-100 year is used for the analysis of the impacts being generated on the transportation infrastructure by such event. A critical map and index is developed to identify affected road length susceptible to flood. It has been observed that more than 40 percent of road length across the network has been affected by such unpredictable events. Also, there is a significant decrease in average speed of movement as compared to average normal speed observed on the normal days.

ABNORMAL CROWDSOURCED DATA DETECTION USING REMOTE SENSING IMAGE FEATURES

Abstract. Quality is the key issue for judging the usability of crowdsourcing geographic data. While due to the un-professional of volunteers and the phenomenon of malicious labeling, there are many abnormal or poor quality objects in crowdsourced data. Based on this observation, an abnormal crowdsourced data detection method is proposed in this paper based on image features. This approach includes three main steps. 1) the crowdsourced vector data is used to segment the corresponding remote sensing imagery to get image objects with a priori information (e.g., shape and category) from vector data and spectral information from the images. Then, the sampling method is designed considering the spatial distribution and topographic properties of the objects, and the initial samples are obtained, although some samples are abnormal object or poor quality. 2) A feature contribution index (FCI) is defined based on information gain to select the optimal features, a feature space outlier index (FSOI) is presented to automatically identify outlier samples and changed objects. The initial samples are refined by an iteration procedure. After the iteration, the optimal features can be determined, and the refined samples with categories can be obtained; the imagery feature space is established using the optimal features for each category. 3) The abnormal objects are identified with the refined samples by calculating the FSOI values of image objects. In order to valid the effectiveness, an abnormal crowdsourced data detection prototype is developed using Visual Studio 2013 and C# programming, the above algorithms and methods are implemented and verified using water and vegetation categories as example, the OSM (OpenStreetMap) and corresponding imagery data of Changsha city as experiment data. The angular second moment (ASM), contrast, inverse difference moment (IDM), mean, variance, difference entropy, and normalized difference green index (NDGI) of vegetation, and the IDM, difference entropy and correlation and maximum band value of water are used to detect abnormal data after the selection of image optimal feature. Experimental results show that abnormal water and vegetation data in OSM can be effectively detected in this method, and the missed detection rate of the vegetation and water are all near to zero, and the positive detection rate reach 90.4% and 83.8%, respectively.

High strength pure chitosan hydrogels via double crosslinking strategy

Chitosan (CS) hydrogels have been widely used throughout basic tissue engineering and regenerative medicine research and it is very desirable to develop advanced CS materials with superior mechanical and topographical properties for more extensive applications. Herein, we present the design of a double crosslinking pure CS hydrogel material via the synergic effect of the chemical covalent network, hydrophobic interactions, enhanced intermolecular hydrogen bonding and the formation of the CS crystallite. The resultant pure CS hydrogel possesses increases in strength and toughness by two orders of magnitude (fracture energy ∼7.733 J m−2; maximal compression stress ∼10.81 MPa, elastic modulus ∼1.33 MPa). We utilize 1H NMR and FT-IR to prove the success of chemical modification. The results of Raman spectra and WXRD have proved the existence of physical interaction between CS hydrogels and microcrystals, thus explaining the enhancement mechanism of mechanical strength of CS hydrogel. The live and death results also show that MSCs can grow well on CS hydrogels, and the results of CCK-8 indicate low cytotoxicity of CS hydrogels. This CS hydrogel shows great potential applications in tissue engineering and regenerative medicine.

Morphometric Characteristics of the Aziana Valley Basin

The present study aims at examining quantitatively the morphometric characteristics of Iziana Valley basin that is located in the northern part of Iraq; particularly in south of Erbil Governorate. This basin is considered one of the small sub-basins where its valleys run on formations of the Triple and Quadrant Ages, which are represented by the Bay Hassan formations, and the sediments and mixed sediments of the cliffs, respectively. The area of ​​the Iziana basin amounts to (36.39 km2) whereas the percentage of its rotation reaches (0.17); a low percentage, which indicates that the basin diverges from the circular to the rectangular shape. The value of the elongation ratio of the basin reaches (0.38) while the terrain ratio of the basin is (0.03), a low percentage that entails the weakness of its erosion processes and the small volume of the carried and transported sediments. As for the relative topography of the basin, it was (1.08), which is also a low value. It indicates a relatively large area of ​​the basin and the impressive strides that it has made in its erosion cycle. The total river levels of the basin reach (5) ranks, and their numbers vary from one rank to another. Moreover, the total length of the drainage networks in the basin reached (187.4 km), and the prevailing drainage patterns in the basin are the tree and parallel patterns. The researcher has adopted spatial, formal, topographical, and river net-work properties for the purpose of first determining the shape of the basin, the stage of its erosion, its secondary basins, and its terrestrial features that have been developed as a result of the contrast between the erosion and sedimentation processes.

Carrier type induced magnetoresistance upending in assembly of sulfur doped Sb2Se3 nanotubes

Materials showing low field induced switch over in magnetoresistance is investigated heavily nowadays for promising power electronics and phase change memory applications. In this work, morphological, topographical, magnetoresistance (MR) and thermoelectric properties of nanobulk assembly of sulfur doped Sb2Se3nanotubes synthesized by novel microwave assisted solvothermal process is investigated and reported. Structural properties indicate that the sample crystallizes in orthorhombic phase while morphology study confirms the formation of nanotubes of length 1–5 μm and diameter 100–150 nm. Electrical resistivity measurements indicates 2D variable range hopping at low temperature (2–50 K), nearest neighbor hopping at intermediate temperature (50–200 K) and thermal activation behavior with activation energy of 2.3 meV from 200 K to 300 K. Interestingly the positive magnetoresistance observed in low magnetic field and at constant low temperatures makes a transition to negative magnetoresistance above 20 K. Bipolaron model along with wave function shrinkage models were invoked to understand the MR measurements while low temperature thermoelectric measurement univocally elucidates that the carrier type switching at 13 K dictates the conduction mechanism as demonstrated by the complex crossover in magnetoresistance.