Drop-like Shape Research Articles

Analytical solution of the cantilevered elastica subjected to a normal uniformly distributed follower load

We report the full analytical solution of the large deformations of a cantilevered elastica loaded by a uniformly distributed follower pressure. We consider an unshearable, inextensible and linear elastic rod. We obtain a spatial nonlinear differential equation in the curvatures, analogous to the undamped Duffing oscillator with a constant driving force. We solve such differential equation, obtaining the curvature, although in implicit form, for arbitrarily large values of the load. We are then able to obtain the rotations owing to a change of variables from the curvilinear abscissa to the curvature. This step is somewhat mandatory due to the implicit nature of the solution. Finally, with the same change of variables, it is possible to obtain a closed-form solution for the deformation in Cartesian coordinates. The solutions show that the rod deforms into drop-like shapes. The number of drops is equal to the number of spatial periods of the solution, which goes with q∗1/3, with q∗ a dimensionless load normalised to the bending stiffness. Interestingly, we find that for q∗⩾3094.2, the number of drop-like shapes does not increase, but remains three.

The dimeric ectodomain of the alkali-sensing insulin receptor–related receptor (ectoIRR) has a droplike shape

Insulin receptor-related receptor (IRR) is a receptor tyrosine kinase of the insulin receptor family and functions as an extracellular alkali sensor that controls metabolic alkalosis in the regulation of the acid-base balance. In the present work, we sought to analyze structural features of IRR by comparing them with those of the insulin receptor, which is its closest homolog but does not respond to pH changes. Using small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM), we investigated the overall conformation of the recombinant soluble IRR ectodomain (ectoIRR) at neutral and alkaline pH. In contrast to the well-known inverted U-shaped (or λ-shaped) conformation of the insulin receptor, the structural models reconstructed at different pH values revealed that the ectoIRR organization has a "droplike" shape with a shorter distance between the fibronectin domains of the disulfide-linked dimer subunits within ectoIRR. We detected no large-scale pH-dependent conformational changes of ectoIRR in both SAXS and AFM experiments, an observation that agreed well with previous biochemical and functional analyses of IRR. Our findings indicate that ectoIRR's sensing of alkaline conditions involves additional molecular mechanisms, for example engagement of receptor juxtamembrane regions or the surrounding lipid environment.

Strengthening the Mechanical Performance of Sea Urchin Skeleton by Tube Feet Pore

In this paper, the effects of tube feet pores on the mechanical properties of Sea Urchin Skeleton (SUS) have been studied. The pore structure of drop-like Tripnenstes gratilla (a sea urchin) skeleton is characterized by Scanning Electron Microscopy (SEM). Based upon the data, the finite element method has been employed to analyze the Maximum Tensile Stress (MTS) of SUS models with different pore positions, accompanied by compressive tests on SUS-like ceramics. Results indicate that for a drop-like SUS, the MTS keeps a linear relationship with the maximum load applied on the SUS. More importantly, the mechanical performances of some perforated SUSs are better than their non-perforated counterparts due to their lower MTS values, e.g. the maximum load can thus be increased by 35% when the pore is perforated at −10°. The strengthening is attributed to the introduced pore that causes the redistribution of stress and partly reduces the stress intensity on the original MTS position. By contrast, the pore only increases the MTS value of a spherical shell under isostatic pressure or unidirectional pressing. This is a strong hint that the drop-like shape of SUS has evolved to work with the tube feet pores to better protect their bodies.

SURGICAL TREATMENT OF BREAST IMPLANTS ROTATION

Relevance. Using anatomical breast implants with high and ultrahigh profile in augmentation mammoplasty provides nearly natural shape of breasts. Using the drop-like shape implants instead of round ones can cause complication called breast implant rotation (BIR), that have negative influence on patients life quality. There is not enough data about the effective methods of surgical treatment of clinically significant rotation.
 Objective of our study was to determine the effectiveness of «neo pocket» upper pole inhancement with mesh for the treatment of BIR after primary submuscular breast augmentation in a postoperative period.
 Materials and methods. The study included 42 women with an average age of 29.4 ± 0.7 years (20 to 39 years) who underwent surgery for a clinically significant (more than 90o) BIR that occurred after the classical primary breast augmentation. Treatment of BIR was performed by enhancement of upper pole of neo-pocket redublication of implant capsule with prolene mesh between the capsule layers and fixation to ribs periosteum and pectoral muscules. The endpoint of the study was the frequency and degree of the prosthesis rotation one year after BIR treatment. Data analysis was performed using the IBM SPSS Statistics 22.
 Results. 13 (31,0%) of patients admitted to hospital for prothesis enlargment and BIR – 29 (69,0%). From 84 number of implants 66 (78,6%) were rotated. Two women (4,7%) had same degree of implants rotation. In all other cases BIR had different angle. Clinically significant rotation of implants was diagnosed in 4 patient: 90 ° / 90 ° two patients; 90° / 150° – one patient ; 90° / 180° – one patient. 38 (90,5%) patients had clinically significant implants rotation. In one year after primary surgery significant BIR (90%) was diagnosed in one patient, who didn’t need breast augmentation, she also had a small rotation of breast on 60о before surgery. From number of breasts, when developed procedure was performed (56), in one case significant BIR was diagnosed, in a patient with preoperative BIR 1800. Significant BIR was diagnosed in 6 (11,5 %) patients, and one patient BIR 60о (1,8 %) and five 300 (8,9%).
 Conclusion: The developed method of «neo pocket» upper pole enhancement by redublication of prothesis capsule with prolene mesh between the capsule layers and fixation to ribs periosteum and pectoral muscules helps to avoid BIR in 98,2% in one year follow up period.

Specific features in the transformation of liquid drops during their motion in a gas medium

Using high-speed video cameras (up to 105 frames per second), a cross-correlation measuring system, and panoramic optical tracer visualization methods, some specific features have been revealed in the transformation of drops of liquids widely used in chemical technologies (kerosene, ethanol, water, acetone). The studies were performed for individual drops with characteristic sizes (radii) of 1–3 mm during their motion through a gas medium (air at a temperature of nearly 300 K) at velocities of 0.5–5 m/s. The ranges of change in the aerodynamic resistance coefficients cd were determined for the studied liquid drops under the considered conditions. The effect of the sizes and velocities of drops on this parameter have been established. Real values of cd for typical applications were shown to be much greater than for the corresponding droplike shapes.

In vitro gastrointestinal-resistant pectin hydrogel particles for β-glucuronidase adsorption

Pectin hydrogel particles (PHPs) were prepared by ionotropic gelation of low methylesterified pectin of Tanacetum vulgare L. with calcium ions. Wet PHPs prepared from TVF exhibited a smaller diameter and the lower weight as well as exhibited the best textural properties in terms of hardness and elasticity compared to the PHPs prepared from commercial low methylesterified pectin (CU701) used for comparison. Upon air drying, PHPs prepared from CU701 became small and dense microspheres whereas the dry PHPs prepared from TVF exhibited a drop-like shape. The morphology of dry PHPs determined by scanning electron microscopy revealed that the surface of the TVF beads exhibited fibred structures, whereas the PHPs prepared from CU701 exhibited a smooth surface. The characterization of surface roughness using atomic force microscopy indicated less roughness profile of the PHPs prepared from TVF than CU701. PHPs prepared from TVF were found to possess in vitro resistance to successive incubations in simulated gastric (SGF), intestinal (SIF), and colonic fluid (SCF) at 37 °C for 2, 4 and 18 h, respectively. The PHPs prepared from CU701 swelled in SGF and then lost their spherical shape and were fully disintegrated after 4 h of incubation in SIF. The PHPs from TVF, which were subjected to treatment with SGF, SIF and SCF, were found to adsorb microbial β-glucuronidase (βG) in vitro. The data obtained offered the prospect for the development of the PHPs from TVF as sorbents of colonic βG for the inhibition of re-absorption of estrogens.

Elaboration of chitosan nanoparticles: Favorable impact of a mild thermal treatment to obtain finely divided, spherical, and colloidally stable objects

The elaboration of chitosan (CS) nanoparticles via an ionic gelation process using sodium tripolyphosphate (TPP) as cross-linking agent was thoroughly studied in order to develop colloidally stable, spherical CS nanoparticles with a reproducible sub-micrometer size, and a narrow size distribution. To this end, the most relevant parameters involved in the synthesis such as CS chains concentration and molecular weight as well as ionic strength and pH of CS initial solutions were investigated and optimized. The physicochemical characterization of resulting CS nanoparticles was carried out in terms of size, size distribution, and surface charge by quasi-elastic light scattering (QELS), nanoparticle tracking analysis (NTA), and zeta potential measurements. Morphological characterization using classical and cryogenic transmission electron microscopy (TEM and cryo-TEM) was then performed revealing a high number of aggregates mixed to individualized nanoparticles with drop-like and irregular shapes. These limitations were overcome by applying a specific and optimized thermal treatment which appeared to significantly reduce the aggregate number, and to restructure the CS nanoparticles into highly spherical objects. Based on all these findings, reproducible, cationic (zeta potential=+37±5mV), stable (at least 4 months at 20°C), spherical, and mainly individualized CS nanoparticles of 100±30nm (determined from cryo-TEM images) were obtained.

DragonFlex – Smart Steerable Laparoscopic Instrument

DragonFlex – Smart Steerable Laparoscopic Instrument

Aerodynamic drag to flows about single drop-like tubes and visualizaton of these flows

Results of experimental investigations of the aerodynamic drag to the cross fl ows about single tubes of drop-like shape in the range of change in the Reynolds number from 9000 to 45,000 are presented. The results obtained were compared with the corresponding experimental data obtained for single round tubes. A visualization of the fl ows over the surfaces of single drop-like and round tubes has been carried out.

Morphology, germination, and storage behaviour in seeds of Tuscan populations of Fritillaria montana (Liliaceae), a rare perennial geophyte in Italy

Fritillaria montana Hoppe ex W.D.J.Koch (Liliaceae) is a rare perennial geophyte growing in south-eastern Europe. Although it occurs in most of the Italian territory, it is very rare and is included in the Red List of threatened plant species of most of the regions in which it grows; in Tuscany (central Italy), it is listed as Critically Endangered. The aim of our study was to investigate the seed size, weight, and morphology; the seed moisture and oil contents; the seed germination conditions; and the effect of different storage treatments on final germination success in F. montana. Seeds were collected from the only Tuscan population that set fruit in 2008, and they were then subjected to morphometric, moisture, and oil content measurements; germination tests; and different storage conditions. Morphometric measurements and shape index evidenced the flat and drop-like shape of the seeds, which have a moisture content of 14.62% and an oil content of 1.09%. They need a period of cold stratification to break dormancy and germinate, with a final percentage of 77.5%. The germination percentage after storage at 5 °C was 70%, while after storage in a drying room it was 55.2%. The differences between the final germination percentage of fresh seeds and treated seeds were only weakly significant. In the short time allotted for the trial, seeds of F. montana showed a good tolerance to drying and a potential predisposition to ex situ conservation techniques.

Observation of ferromagnetism in PdCo alloy nanoparticles encapsulated in carbon nanotubes

Carbon nanotubes terminated by PdCo catalyst nanoparticles were grown by plasma-enhanced chemical vapor deposition. Transmission electron microscopy reveals that these nanoparticles have a droplike shape and are completely encapsulated inside multiwalled nanotubes. Magnetization measurements showed the existence of a permanent magnetization with a small shape anisotropy effect. The magnetization of both cobalt and palladium was confirmed by x-ray magnetic circular dichroism. These results show that nanotubes ended by magnetic PdCo nanoparticles can be grown and could be used in magnetic storage media and electrical spin injection.

Dynamics of reactive high-power impulse magnetron sputtering discharge studied by time- and space-resolved optical emission spectroscopy and fast imaging

Time- and space-resolved optical emission spectroscopy and fast imaging were used for the investigation of the plasma dynamics of high-power impulse magnetron sputtering discharges. 200 μs pulses with a 50 Hz repetition frequency were applied to a Cr target in Ar, N2, and N2/Ar mixtures and in a pressure range from 0.7 to 2.66 Pa. The power density peaked at 2.2–6 kW cm−2. Evidence of dominating self-sputtering was found for all investigated conditions. Up to four different discharge phases within each pulse were identified: (i) the ignition phase, (ii) the high-current metal-dominated phase, (iii) the transient phase, and (iv) the low-current gas-dominated phase. The emission of working gas excited by fast electrons penetrating the space in-between the electrodes during the ignition phase spread far outwards from the target at a speed of 24 km s−1 in 1.3 Pa of Ar and at 7.5 km s−1 in 1.3 Pa of N2. The dense metal plasma created next to the target propagated in the reactor at a speed ranging from 0.7 to 3.5 km s−1, depending on the working gas composition and the pressure. In fact, it increased with higher N2 concentration and lower pressure. The form of the propagating plasma wave changed from a hemispherical shape in Ar, to a droplike shape extending far from the target in N2. An important N2 emission rise in the latter case was detected during the transition at the end of the metal-dominated phase.

Interlayer cooling potential in vertically integrated packages

The heat-removal capability of area-interconnect-compatible interlayer cooling in vertically integrated, high-performance chip stacks was characterized with de-ionized water as coolant. Correlation-based predictions and computational fluid dynamic modeling of cross-flow heat-removal structures show that the coolant temperature increase due to sensible heat absorption limits the cooling performance at hydraulic diameters ≤200 μm. An experimental investigation with uniform and double-side heat flux at Reynolds numbers ≤1,000 and heat transfer areas of 1 cm2 was carried out to identify the most efficient interlayer heat-removal structure. The following structures were tested: parallel plate, microchannel, pin fin, and their combinations with pins using in-line and staggered configurations with round and drop-like shapes at pitches ranging from 50 to 200 μm and fluid structure heights of 100–200 μm. A hydrodynamic flow regime transition responsible for a local junction temperature minimum was observed for pin fin in-line structures. The experimental data was extrapolated to predict maximal heat flux in chip stacks having a 4-cm2 heat transfer area. The performance of interlayer cooling strongly depends on this parameter, and drops from >200 W/cm2 at 1 cm2 and >50 μm interconnect pitch to <100 W/cm2 at 4 cm2. From experimental data, friction factor and Nusselt number correlations were derived for pin fin in-line and staggered structures.

Effect of Silica Additive on the Formation of Lotus-Type Porous Alumina under Unidirectional Solidification

Effect of silica additive on the formation of lotus-type porous alumina on the unidirectional solidification was examined. Lotus-type porous alumina with 44% porosity was formed by unidirectional solidification using the optical floating zone method under a hydrogen atmosphere when low purity alumina was used as the feed rod. However, non-porous alumina was prepared in argon atmosphere. The formed pores possessed a drop-like shape and were elongated along the solidification direction in porous alumina. Gas bubbles evolved in the molten zone and was trapped by the solid/liquid interface during the unidirectional solidification. On the other hand, lotus-type porous alumina could not be obtained when high purity alumina was used as the feed rod. The porosity of the solidified porous alumina increased with increasing silica contents in the feed rods.

Correction for Johnson et al. , Sutural loosening and skeletal flexibility during growth: determination of drop-like shapes in sea urchins

Correction for ‘Sutural loosening and skeletal flexibility during growth: determination of drop-like shapes in sea urchins’ by A. S. Johnson, O. Ellers, J. Lemire, M. Minor and H. A. Leddy (Proc. R. Soc. Lond. B 269 , 215–220. (doi: 10.1098/rspb.2001.1881)). On page 215, the digital object identifier was incorrectly given. It should read 10.1098/rspb.2001.1881.

Sutural loosening and skeletal flexibility during growth: determination of drop-like shapes in sea urchins.

The shape of sea urchins may be determined mechanically by patterns of force analogous to those that determine the shape of a water droplet. This mechanical analogy implies skeletal flexibility at the time of growth. Although comprised of many rigid calcite plates, sutural collagenous ligaments could confer such flexibility if the sutures between plates loosened and acted as joints at the time of growth. We present experimental evidence of such flexibility associated with weight gain and growth. Over 13-, 4-, and 2-week periods, fed urchins (Strongylocentrotus droebachiensis) gained weight and developed looser sutures than unfed urchins that maintained or lost weight. Further, skeletons of fed urchins force-relaxed more than did those of unfed urchins and urchins with loose sutures force-relaxed more than those with tight sutures. Urchins (Strongylocentrotus franciscanus) fed for two and a half weeks, gained weight, also had looser skeletons and deposited calcite at sutural margins, whereas unfed ones did not. In field populations of S. droebachiensis the percentage having loose sutures varied with urchin diameter and reflected their size-specific growth rate. The association between feeding, weight gain, calcite deposition, force relaxation and sutural looseness supports the hypothesis that urchins deform flexibly while growing, thus determining their drop-like shapes.

Theoretical model of crystal growth shaping process

Abstract A theoretical investigation of the crystal growth shaping process is carried out on the basis of the dynamic stability concept. The capillary dynamic stability of shaped crystal growth processes for various forms of the liquid menisci is analyzed using the mathematical model of the phenomena in the axisymmetric case. The catching boundary condition of the capillary boundary problem is considered and the limits of its application for shaped crystal growth modeling are discussed. The static stability of a liquid free surface is taken into account by means of the Jacobi equation analysis. The result is that a large number of menisci having drop-like shapes are statically unstable. A few new non-traditional liquid meniscus shapes (e.g., bubbles and related shapes) are proposed for the case of a catching boundary condition.

Platinum-Group Minerals from the Durance River Alluvium, France

Platinum-group minerals were discovered, during gold recovery, in the Durance river alluvium, near Peyrolles (Bouches-du-Rhone). The PGM grains (average size 130 microns) are strongly flattened (average thickness 64 microns). The PGM concentrate consists primarily of (Pt, Fe) alloys (92%), (Os, Ir, Ru) alloys (3.5%), and native gold and (Au, Cu, Ag) alloys (4.5%). The following minerals were observed: isoferroplatinum, ferroan platinum, native osmium, native iridium, iridosmine, rutheniridosmine, osmiridium, ruthenian osmium, osmian ruthenium, cuprorhodsite, guanglinite, shandite, tetrauricupride, native gold, bornite, heazlewoodite, (Pt, Pd)2Cu3, Pt(Cu, Au), (Ni, Pt)Sn, (Cu, Fe)1−x (Pd, Rh, Pt)2+xS2, (Pt, Pd)4−xCu2As1−x. Isoferroplatinum contains numerous inclusions of alloys, sulphides, arsenides, Pd-tellurides, and partly devitrified silicate glass droplets. Most of the non-silicate inclusions also exhibit a drop-like shape indicating their original entrapment in a liquid state.

Platelet adhesion and aggregation in the glass bead column method (Hellem-II): a scanning electron microscope study.

Scanning electron microscope observation was carried out to examine what happens in the glass bead columns during the platelet adhesiveness test. The columns were perfused with different volumes of blood from four normal subjects, and after perfusion of glutaraldehyde and acetone and air drying, the beads were partially embedded in epoxy resin. Bunches of the beads were cut out and their surfaces freed of resin contamination were observed.Many platelets and erythrocytes were found on the beads. The platelets showed different stages of a process in which, as in our previous experiment on the platelet attitude to glass plate, a few of them first adhered to the glass surface and then further platelets became attached to them, forming larger and larger aggregates. The aggregated platelets showed the same features as those in the ADP-induced primary aggregates in vitro. The erythrocytes were found to be attached to the glass, deformed into a drop-like shape and finally ruptured by blood flow.It was concluded that the result of this method mainly reflects the aggregation probably caused by ADP from hemolysis occurring on the beads.