scholarly journals Designing bioinspired surfaces for water collection from fog

2018 ◽  
Vol 377 (2138) ◽  
pp. 20180269 ◽  
Author(s):  
Dev Gurera ◽  
Bharat Bhushan
Keyword(s):  
Flat Surface ◽  
Unit Area ◽  
Water Repellency ◽  
Vertical Axis ◽  
Collection Rate ◽  
Flat Surfaces ◽  
Single Cone ◽  
Water Collection ◽  
The Difference ◽  
Conical Surfaces

A systematic study is presented on various water collectors, bioinspired by desert beetles, desert grass and cacti. Three water collecting mechanisms including heterogeneous wettability, grooved surfaces, and Laplace pressure gradient, were investigated on flat, cylindrical, conical surfaces, and conical array. It is found that higher water repellency in flat surfaces results in higher water collection rate and inclination angle (with respect to the vertical axis) has little effect. Surfaces with heterogeneous wettability have higher water collection rate than surfaces with homogeneous wettability. Both cylindrical and conical surfaces resulted in comparable water collection rate. However, only the cone transported the water droplets to its base. Heterogeneity, higher inclination and grooves increased the water collection rate. A cone has a higher collection rate per unit area than a flat surface with the same wettability. An array of cones has higher collection rate per unit area than a single cone, because droplets in a conical array coalesce, leading to higher frequency of droplets falling. Adding heterogeneity further increases the difference. Based on the findings, scaled-up designs of beetle-, grass- and cactus-inspired surfaces and nets are presented. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology’.

Protein Fingerprinting Using Flat-Surface Electrophoresis

2007 ◽  
Vol 1061 ◽  
Author(s):  
Perumal Radha Ramasamy ◽  
Raafat Elmaghrabi ◽  
Gary Halada ◽  
Miriam Rafailovich
Keyword(s):  
Flat Surface ◽  
Dominant Role ◽  
Flat Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Protein Fingerprinting ◽  
The Difference ◽  
Glass Surfaces ◽  
Oppositely Charged ◽  
Electrophoresis Of Proteins

ABSTRACTDevelopments in the field of proteomics are highly encouraging for medical researchers. While gel electrophoresis offers a successful means for protein recognition, it requires the use of a relatively large system and a rather long period of time. Here, a protocol is developed for electrophoresis of proteins using flat surfaces based on the principles of electrophoresis of DNA on flat surfaces. By further adapting this system, it is hoped to create a portable device for protein electrophoresis. Droplets of fluorescently tagged proteins such as albumin, casein, poly-L-lysine and their mixtures were placed on glass surfaces in an electrophoretic cell and allowed to dry. TBE buffer was added to the cell and the migration of the salt complexes was monitored using confocal microscopy. We show that different protein - salt complexes have different mobilities on a flat surface. The shape and size distributions of the protein-salt complexes and their mixtures on surfaces were also studied using atomic force microscopy and were found to be dependent upon the proteins. It is observed that the native charge of the proteins play a dominant role in the migration of the protein-salt complexes in the electrophoretic cell. From the morphology of the protein droplets it is observed that large aggregates are formed when oppositely charged proteins are mixed. Light scattering measurements and zeta potential measurements confirm the difference in the size and shape of the aggregates in solution leading to different mobilities of the protein-salt aggregates during electrophoresis.

Determination of Resistance to Abrasive Wear. VIII. Influence of Softeners in Tests with the Akron-Croydon and Du Pont Machines

1949 ◽  
Vol 22 (1) ◽  
pp. 259-262
Author(s):  
J. F. Morley
Keyword(s):  
Unit Area ◽  
Published Data ◽  
The Road ◽  
Abrasive Surface ◽  
Abrasive Power ◽  
The Difference ◽  
On The Road ◽  
The Right ◽  
Abrasion Testing

Abstract These experiments indicate that softeners can influence abrasion resistance, as measured by laboratory machines, in some manner other than by altering the stress-strain properties of the rubber. One possible explanation is that the softener acts as a lubricant to the abrasive surface. Since this surface, in laboratory abrasion-testing machines, is relatively small, and comes repeatedly into contact with the rubber under test, it seems possible that it may become coated with a thin layer of softener that reduces its abrasive power. It would be interesting in this connection to try an abrasive machine in which a long continuous strip of abrasive material was used, no part of it being used more than once, so as to eliminate or minimize this lubricating effect. The fact that the effect of the softener is more pronounced on the du Pont than on the Akron-Croydon machine lends support to the lubrication hypothesis, because on the former machine the rate of wear per unit area of abrasive is much greater. Thus in the present tests the volume of rubber abraded per hr. per sq. cm. of abrasive surface ranges from 0.03 to 0.11 cc. on the du Pont machine and from 0.0035 to 0.0045 cc. on the Akron-Croydon machine. On the other hand, if the softener acts as a lubricant, it would be expected to reduce considerably the friction between the abrasive and the rubber and hence the energy used in dragging the rubber over the abrasive surface. The energy figures given in the right-hand columns of Tables 1 and 3, however, show that there is relatively little variation between the different rubbers. As a test of the lubrication hypothesis, it would be of interest to vary the conditions of test so that approximately the same amount of rubber per unit area of abrasive is abraded in a given time on both machines; this should show whether the phenomena observed under the present test conditions are due solely to the difference in rate of wear or to an inherent difference in the type of wear on the two machines. This could most conveniently be done by considerably reducing the load on the du Pont machine. In the original work on this machine the load was standardized at 8 pounds, but no figures are quoted to show how abrasion loss varies with the load. As an addition to the present investigation, it is proposed to examine the effect of this variation with special reference to rubbers containing various amounts and types of softener. Published data on the influence of softeners on the road wear of tire rubbers do not indicate anything like such large effects as are shown by the du Pont machine. This throws some doubt on the value of this machine for testing tire tread rubbers, a conclusion which is confirmed by information obtained from other workers.

scholarly journals Fuel and lubricant consumption in felling the young oak-hornbeam stands

2002 ◽  
pp. 59-66
Author(s):  
Vojislav Bajic ◽  
Milorad Danilovic
Keyword(s):  
Statistical Analysis ◽  
Analysis Of Variance ◽  
Unit Area ◽  
Function Form ◽  
Tree Diameter ◽  
Significant Difference ◽  
The Difference ◽  
Level Of Significance ◽  
Average Consumption

Based on the elements of statistical analysis on the dependence of fuel and lubricant consumption on tree diameter, it was assessed that with the increase of tree diameter, the fuel and lubricant consumption in the young oak and hornbeam stands decreases significantly, both in clear felling and in thinning and that the function form Y=exp(a+b x X?1) is the best description of the correlation The consumption of fuel compared to lubricant consumption is almost double, which agrees with the results of the previous studies. Average consumption of fuel and lubricant is 17.43 mL x tree?1, on the plots 20.27 mL x tree?1, average consumption of lubricant per tree on skid roads is 9.4 mL x tree?1, on the plots 11 mL x tree?1. The higher consumption of fuel and lubricant on the plots with selective thinning is the consequence of the longer time needed for the conversion per tree, compared to that in clear felling The consumption of fuel per unit area on the skid roads (clear felling) is 22.9 L x ha?1, on the plots (selective thinning) 7.6 L x ha?1. The consumption of lubricant on the skid roads is 13.3 L x ha?1, on the plots 4.29 L x ha?1. The higher consumption of fuel and lubricant per unit area on the skid roads is due to the difference in the number of trees per unit area Based on the results of the analysis of variance, it was found out that between fuel and lubricant consumption in selective thinning and in felling the trees along tractor skid roads there is no statistically significant difference at the level of significance of 95%. So, for practical purposes, the unique norms of consumption can be established for the stands similar to those in which the study was performed.

Small theropod and bird teeth from the late Cretaceous (late Campanian) Judith River Group, Alberta

2002 ◽  
Vol 76 (4) ◽  
pp. 751-763 ◽  
Author(s):  
Julia T. Sankey ◽  
Donald B. Brinkman ◽  
Merrilee Guenther ◽  
Philip J. Currie
Keyword(s):  
Late Cretaceous ◽  
Flat Surface ◽  
Flat Surfaces ◽  
Wear Pattern ◽  
A Share

A collection of over 1,700 small theropod teeth from the Judith River Group (Campanian;˜79.5–74 Ma) allows our understanding of the diversity and variation of small theropods in this assemblage to be refined. In addition to the previously recognized taxa, a series of morphologically distinct groups are recognized that may represent distinct taxa in some cases. Teeth with the Paronychodon-like features of a flat surface with longitudinal ridges on one side are resolved into a few discrete morphotypes. Two of these are included in Paronychodon lacustris and two additional morphotypes are hypothesized to represent distinct taxa, here referred to as ?Dromaeosaurus morphotype A and Genus and species indet. A. The teeth of Paronychodon lacustris and ?Dromaeosaurus morphotype A share a distinctive wear pattern that suggests tooth functioning involved contact between the flat surfaces of opposing teeth. Two species of Richardoestesia, R. gilmorei and R. isosceles, are present in the assemblage. Additionally, bird teeth are identified in the assemblage and are described in this review.Bivariate plots were used to document the variation in the theropod teeth, especially in the features that distinguish between Richardoestesia gilmorei, R. isosceles, Saurornitholestes, and Dromaeosaurus. Considerable overlap is present in all plots, so although the teeth are morphologically distinct, they are not easily distinguished by quantitative means.

scholarly journals Exercise tolerance during flat over-ground intermittent running: modelling the expenditure and reconstitution kinetics of work done above critical power

2019 ◽  
Vol 120 (1) ◽  
pp. 219-230
Author(s):  
Christian Vassallo ◽  
Adrian Gray ◽  
Cloe Cummins ◽  
Aron Murphy ◽  
Mark Waldron
Keyword(s):  
Critical Power ◽  
Specific Model ◽  
Threshold Velocity ◽  
Positioning Systems ◽  
Flat Surfaces ◽  
Constant Work Rate ◽  
The Difference ◽  
Uptake Velocity ◽  
Work Done ◽  
W Prime

Abstract Purpose We compared a new locomotor-specific model to track the expenditure and reconstitution of work done above critical power (W´) and balance of W´ (W´BAL) by modelling flat over-ground power during exhaustive intermittent running. Method Nine male participants completed a ramp test, 3-min all-out test and the 30–15 intermittent fitness test (30–15 IFT), and performed a severe-intensity constant work-rate trial (SCWR) at the maximum oxygen uptake velocity (vV̇O2max). Four intermittent trials followed: 60-s at vV̇O2max + 50% Δ1 (Δ1 = vV̇O2max − critical velocity [VCrit]) interspersed by 30-s in light (SL; 40% vV̇O2max), moderate (SM; 90% gas-exchange threshold velocity [VGET]), heavy (SH; VGET + 50% Δ2 [Δ2 = VCrit − VGET]), or severe (SS; vV̇O2max − 50% Δ1) domains. Data from Global Positioning Systems were derived to model over-ground power. The difference between critical and recovery power (DCP), time constant for reconstitution of W´ ($$\tau_{{W^{\prime}}}$$τW′), time to limit of tolerance (TLIM), and W´BAL from the integral (W´BALint), differential (W´BALdiff), and locomotor-specific (OG-W´BAL) methods were compared. Results The relationship between $$\tau_{{W^{\prime}}}$$τW′ and DCP was exponential (r2 = 0.52). The $$\tau_{{W^{{\prime}}}}$$τW′ for SL, SM, and SH trials were 119 ± 32-s, 190 ± 45-s, and 336 ± 77-s, respectively. Actual TLIM in the 30–15 IFT (968 ± 117-s) compared closely to TLIM predicted by OG-W´BAL (929 ± 94-s, P > 0.100) and W´BALdiff (938 ± 84-s, P > 0.100) but not to W´BALint (848 ± 91-s, P = 0.001). Conclusion The OG-W´BAL accurately tracked W´ kinetics during intermittent running to exhaustion on flat surfaces.

scholarly journals Laser-written colours on silver: optical effect of alumina coating

Nanophotonics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 807-822 ◽  
Author(s):  
Jean-Michel Guay ◽  
Antonino Calà Lesina ◽  
Graham Killaire ◽  
Peter G. Gordon ◽  
Choloong Hahn ◽  
...  
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Flat Surface ◽  
Atomic Layer ◽  
Alumina Coating ◽  
Optical Effect ◽  
Alumina Film ◽  
Flat Surfaces ◽  
Layer Deposition ◽  
Difference Time

AbstractIn this paper we discuss the optical response of laser-written plasmonic colours on silver coated via the atomic layer deposition of alumina. These colours are due to nanoparticles distributed on a flat surface and on a surface with periodic topographical features (i.e. ripples). The colours are observed to shift with increasing alumina film thickness. The colours produced by surfaces with ripples recover their original vibrancy and hue after the deposition of film of thickness ~60 nm, while colours arising from flat surfaces gradually fade and never recover. Analysis of the surfaces identifies periodic topographical features to be responsible for this behaviour. Finite-difference time-domain simulations unravel the role played by the alumina thickness in colour formation and confirm the rotations and recovery of colours for increasing alumina thickness. The coloured surfaces were evaluated for applications in colourimetric and radiometric sensing showing large sensitivities of up to 3.06/nm and 3.19 nm/nm, respectively. The colourimetric and radiometric sensitivities are observed to be colour dependent.

A compact stair-climbing wheelchair with two 3-DOF legs and a 1-DOF base

2016 ◽  
Vol 43 (2) ◽  
pp. 181-192 ◽  
Author(s):  
Chang-Hyuk Lee ◽  
Kyung-min Lee ◽  
Jehong Yoo ◽  
In-su Kim ◽  
Young-bong Bang
Keyword(s):  
Degrees Of Freedom ◽  
Flat Surface ◽  
Estimation Method ◽  
Stable Condition ◽  
Stair Climbing ◽  
Joint Power ◽  
Content Type ◽  
Flat Surfaces ◽  
Simple Estimation ◽  
The Stability

Purpose – The purpose of this paper is to describe a compact wheelchair, which has two 3-degrees of freedom (DOF) legs and a 1-DOF base (the total DOF of the leg system is 7) for stair-climbing, and wheels for flat surface driving. Design/methodology/approach – The proposed wheelchair climbs stairs using the two 3-DOF legs with boomerang-shaped feet. The leg mechanisms are folded into the compact wheelchair body when the wheelchair moves over flat surfaces. The authors also propose a simple estimation method of stair shape using laser distance sensors, and a dual motor driving system to increase joint power. Findings – The proposed wheelchair can climb arbitrary height and width stairs by itself, even when they are slightly curved. During climbing, the trajectory of the seat position is linear to guarantee the comfort of rider, and the wheelchair always keeps a stable condition to ensure the stability in an emergency stop. Originality/value – The wheelchair mechanism with foldable legs and driving wheels enables smooth stair climbing, efficient flat surface driving and additional useful motions such as standing and tilting.

Electrical, Optical, Structural, and Analytical Properties of Very Pure GaN

2002 ◽  
Vol 743 ◽  
Author(s):  
D. C. Look ◽  
J. R. Sizelove ◽  
J. Jasinski ◽  
Z. Liliental-Weber ◽  
K. Saarinen ◽  
...  
Keyword(s):  
Activation Energy ◽  
Hall Effect ◽  
Excited States ◽  
Vacancy Concentration ◽  
Strong Line ◽  
Threading Dislocation ◽  
Charge Balance ◽  
Acceptor Concentration ◽  
Flat Surfaces ◽  
The Difference

ABSTRACTPresent hydride vapor phase epitaxial growth of GaN on Al2O3 can produce material of very high quality, especially in regions of the crystal far from the substrate/epilayer interface. In the present study, we characterize a 248-μm-thick epilayer, which had been separated from its Al2O3 substrate and etched on top and bottom to produce flat surfaces. Temperature-dependent Hall-effect data have been fitted to give the following parameters: mobility μ(300) = 1320 cm2/V-s; μ(peak) = 12,000 cm2/V-s; carrier concentration n(300) = 6.27 × 1015 cm−3; donor concentration ND = 7.8 × 1015 cm−3; acceptor concentration NA = 1.3 × 1015 cm−3; and effective donor activation energy ED = 28.1 meV. These mobilities are the highest ever reported in GaN, and the acceptor concentration, the lowest. Positron annihilation measurements give a Ga vacancy concentration very close to NA, showing that the dominant acceptors are likely native defects. Secondary ion mass spectroscopic measurements show that ND is probably composed of the common donors O and Si, with [O] > [S1]. Transmission electron microscopy measurements yield threading dislocation densities of about 1 × 107 cm−2 on the bottom (N) face, and < 5 × 105 cm−2 on the top (Ga) face. Photoluminescence (PL) spectra show a strong donor-bound exciton (D°X) line at 3.47225 eV, and a weaker one at 3.47305 eV; each has a linewidth of about 0.4 meV. In the two-electron satellite region, a strong line appears at 3.44686 eV, and a weaker one at 3.44792 eV. If the two strong lines represent the same donor, then ED,n=1 – ED,n=2 = 25.4 meV for that donor, and the ground-state activation energy (EC – ED,n=1) is (4/3)25.4 = 33.9 meV in a hydrogenic model, and 32.7 meV in a somewhat modified model. The measured Hall-effect donor energy, 28.1 meV, is smaller than the PL donor energy, as is nearly always found in semiconductors. We show that the difference in the Hall and PL donor energies can be explained by donor-band conduction via overlapping donor excited states, and the effects of non-overlapping excited states which should be included in the n vs. T data analysis (charge balance equation).

Fabrication of Porous Metal Bonded Diamond Grinding Wheels for Flat-Surface Nanomachining

MRS Bulletin ◽  
2001 ◽  
Vol 26 (7) ◽  
pp. 544-546 ◽  
Author(s):  
Koji Matsumaru ◽  
Atsushi Takata
Keyword(s):  
Flat Surface ◽  
Porous Metal ◽  
Small Scale ◽  
Grinding Wheels ◽  
Related Area ◽  
Flat Surfaces ◽  
Diamond Grinding ◽  
The Creation

The articles thus far in this MRS Bulletin issue on Emerging Methods for Micro- and Nanofabrication have addressed the creation of structures or devices on a small scale. What is implicit in some of these articles is that a substrate of sufficient flatness is available upon which to build these structures in a controlled way. A related area, therefore, is the formation of these flat surfaces, as well as the development of the tools to make them.

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