Lateral Shrinkage Research Articles

Coke shrinkage and coking pressure during carbonization in a coke oven

The relationship between coking pressure, lateral shrinkage and vertical shrinkage during carbonization in the coke oven was investigated. During the early and middle stage of the carbonization, no lateral shrinkage (gap between the coke cake and the oven wall) is observed since the outer coke layer is pressed against the oven walls by the coking pressure. It is not until the coking pressure peak ends in the later stage of the carbonization process that the lateral shrinkage starts to develop. The horizontal contraction of coke across the oven width is distributed between the lateral shrinkage and the gap at the oven centre. The final measured lateral shrinkage is 2–5 mm and increases only by 1.6 mm per 10% increase in volatile matter. The coke cake is prevented from shrinking vertically when the coking pressure is high. The coke cake starts to shrink vertically when the downward force (the weight of coke cake) becomes greater than the upward frictional force between the coke cake and the oven wall, which is caused by the coking pressure. The later the coke cake starts to shrink vertically, the smaller the final vertical coke shrinkage.

Distortions in pixel-matched holographic data storage due to lateral dimensional change of photopolymer storage media

Dimensional changes in polymerizable storage materials during exposure are a source of pixel misregistration in digital holographic storage. Lateral shrinkage or expansion of photopolymer recording materials can be deduced from quantitative measurement of the shift and the magnification errors of reconstructed holograms.

Ring Shrinkage Test for Expansive Clays: A Suggested Simple Test Method for Determining Vertical, Lateral, and Volumetric Shrinkage Potential

Abstract The ring shrinkage test is proposed as a new soil testing method for expansive clays to describe quantitatively the soil shrinkage potential. The test provides direct measurements of the linear shrinkage in the form of vertical and lateral changes. In addition, the test provides an alternative test method for determining the shrinkage limit and volumetric shrinkage. The method requires undisturbed samples, and it utilizes the standard oedometer ring of consolidation testing equipment. Description of the proposed test method is presented including details of specimen preparation and data measurements.

Volume Shrinkage in Slant Fringe Gratings of a Cationic Ring-Opening Holographic Recording Material

A new photopolymer holographic recording material, ULSH-500, based on cationic ring-opening polymerization, has been further optimized to achieve low transverse shrinkage without sacrificing sensitivity. The extent of transverse (z) and lateral (x) shrinkage was determined explicitly in this study for a range of slant angles in volume holograms recorded to near saturation and in holograms of low diffraction efficiency. The values ΔKx/Kx and ΔKz/Kz, which represent the physical material shrinkage in the grating vector plane, were ascertained by (1) direct measurement of the differential angle changes in the reference and signal beam angles necessary to achieve Bragg matching and (2) measurement of the average refractive index. The accuracy of this method was primarily limited by the exactness in determining the angle of peak efficiency in the Bragg selectivity curve. It is demonstrated that the peak angle can be established to within a small fraction of a degree. It is shown that the assumption of anchoring and, thus, uniaxial shrinkage as embodied in the conventional fringe rotation model cannot be applied for the photopolymer ULSH-500 under the recording conditions used herein. It is demonstrated that background uplift in angular selectivity profiles can be attributed to nonuniformity in the grating strength throughout the transverse direction of the recording media, and that the uplift can be reduced to negligible levels by using a low fluence pre-imaging exposure. Calorimetric analysis of reaction kinetics was performed using direct laser irradiation delivered by optical fiber.

Properties of metal sheets with 3-D designed surface microgeometry prepared by special rolls

Aluminium sheets are processed to have circular surface microcavities of 100 μm in diameter and 10 to 20 μm deep by a combined process of ion-beam etching, rotary coining of rolls and passive rolling. The deformation and lubrication behaviour of the sheets in sheet metal forming are simulated by a strip draw test using round dies. The slid surfaces ofthe sheets are analyzed by a Scanning Laser Microscope (SLM) and Atomic Force Microscope (AFM) to obtain quantitative evaluation of the change in surface microgeometry. It is found that the surface microcavities show lowered friction even in low viscosity oil lubrication. The deformation of the microcavities and, hence, lubrication process is decomposed to the following stages: (a) preliminary flattening, (b) lateral shrinkage, (c) establishing mechanical seal under compression and sliding, and (d) unloading. A quantitative change in microcavity capacity suggests a major effect of squeezing the before establishing mechanical seal.

Thickness measurement of hydrated and dehydrated cryosections by EELS.

Electron energy-loss spectroscopy (EELS) provides a useful method for determining the thickness of frozen-hydrated and dehydrated cryosections in terms of the inelastic mean free path. Cryosection thickness is an important parameter because plural inelastic scattering limits the sensitivity of elemental microanalysis based on core-loss EELS, and because overlapping structures can affect interpretation of microanalytical data as well as the quality of electron images. The purpose of this work was to establish the minimum practical thickness for cutting cryosections and to explain the measured values for hydrated and dehydrated specimens. Hydrated sections were typically found to be between 1.5-2.5 times thicker than expected from the nominal microtome setting; this difference can be largely explained by compression during cutting. Comparison of micrographs from hydrated and dehydrated cryosections of rapidly-frozen, vitrified liver revealed a lateral shrinkage of approximately 20% on drying. The measured compression and shrinkage factors are consistent with dark-field scanning transmission electron microscopy (STEM) mass measurements on freeze-dried sections. Freeze-dried cryosections, cut to a nominal thickness of 90 nm and supported on thin Formvar/carbon films, had a relative thickness t/lambda i in the range of 0.5 for cytoplasm to 0.9 for mitochondria when analyzed at 100 keV beam energy. Mass loss of approximately 30% occurring at high electron dose enabled useful core-loss spectra to be recorded even from high-mass compartments such as mitochondria without excessive plural scattering.

Thickness measurement of hydrated and dehydrated cryosections by EELS

Electron energy-loss spectroscopy (EELS) provides a useful method for determining the thickness of frozen-hydrated and dehydrated cryosections in terms of the inelastic mean free path. Cryosection thickness is an important parameter because plural inelastic scattering limits the sensitivity of elemental microanalysis based on core-loss EELS, and because overlapping structures can affect interpretation of microanalytical data as well as the quality of electron images. The purpose of this work was to establish the minimum practical thickness for cutting cryosections and to explain the measured values for hydrated and dehydrated specimens. Hydrated sections were typically found to be between 1.5–2.5 times thicker than expected from the nominal microtome setting; this difference can be largely explained by compression during cutting. Comparison of micrographs from hydrated and dehydrated cryosections of rapidly-frozen, vitrified liver revealed a lateral shrinkage of ∼20% on drying. The measured compression and shrinkage factors are consistent with dark-field scanning transmission electron microscopy (STEM) mass measurements on freeze-dried sections. Freeze-dried cryosections, cut to a nominal thickness of 90 nm and supported on thin Formvar/carbon films, had a relative thickness t/λi in the range of 0.5 for cytoplasm to 0.9 for mitochondria when analyzed at 100 keV beam energy. Mass loss of ∼30% occurring at high electron dose enabled useful core-loss spectra to be recorded even from high-mass compartments such as mitochondria without excessive plural scattering. © 1996 Wiley-Liss, Inc.

In vitro changes in nonfacial human skin following CO2 laser resurfacing: A comparison study

Background and Objective We evaluated the physical changes in human skin following CO2 laser cutaneous resurfacing with either the Sharplan SilkTouch® handpiece or the Coherent UltraPulse® laser. Study Design/Materials and Methods Three-hundred five human tissue samples and matched controls were used. Up to five laser passes were performed per specimen. Parameters evaluated included: lateral skin shrinkage, transient temperature change, isometric tension development, elasticity change, and histologic change. Results Skin shrinkage increased in direct proportion to laser pass number. Isometric tension exponentially increased and elasticity exponentially decreased with successive laser passes. The zone of thermal denaturation for the SilkTouch® handpiece was 115 ± 15 μm, and was independent of laser pass number. The zone of thermal denaturation was patchy for the UltraPulse® laser treatments, regardless of pass number. A greater temperature increase was also measured for SilkTouch® irradiation than with the UltraPulse® laser. Conclusion The observed alterations in tissue length, tension development, and elasticity obtained with SilkTouch® or UltraPulse® treatment may contribute to the changes in clinical appearance associated with laser cutaneous resurfacing. Our findings support a role for extracellular matrix contraction in the mechanism of action for CO2 lasers in cutaneous resurfacing. © 1996 Wiley-Liss, Inc.

The impact of soil structure and confining stress on the hydraulic conductivity of clays in brine environments

Numerous studies have been completed in recent years on the alteration of the hydraulic conductivity of clayey soils as a result of exposure to concentrated organic or inorganic permeants. These hydraulic conductivity changes have been attributed to either changes in microstructure, due to contraction of the diffuse double layer, or to the alteration of the macrostructure, as a result of volume changes leading to shrinkage fractures or fissures. In this paper, the change in hydraulic conductivity of a highly plastic natural clay during exposure to a concentrated sodium chloride (NaCl) solution is described. The performance of samples with three different initial soil structures, prepared by slurry, static compaction, and kneading compaction, were investigated under various levels of confining stress. Hydraulic conductivity tests were carried out before and after the samples were exposed to the NaCl solutions. Scanning electron microscope photography was used to compare the soil structures before and after brine permeation. The test results show that the alteration of hydraulic conductivity is strongly related to the initial soil structure and the level of confining stress. No significant change in the microfabric of the clay was observed; however, the size of the interaggregate pores appeared to increase as a result of the physicochemical volume change that occurred during brine permeation. The increase in hydraulic conductivity that occurred during brine permeation could be prevented by increasing the level of confining stress. The stress levels at which significant increases in hydraulic conductivity occurred appeared to be coincident with low levels of vertical stress which allowed the sample to undergo lateral shrinkage and a subsequent loss of confinement. Key words : hydraulic conductivity, clay soils, osmotic consolidation, sodium chloride brine, soil structure, scanning electron microscope.

Rigid-rod molecular composites via ionic interactions

The first example of ionic molecular composites, i.e. the formation of rigid-rod molecular composites via ionic interactions between the polyelectrolyte host and the reinforcing rigid-rod polymer, was provided by the physical blend of poly(2-acrylamido-2-methylpropanesulphonic acid) (HAMPS homopolymer) and poly( p-phenylene benzobisthiazole) (PBZT). HAMPS homopolymer was formed in situ from its sodium salt form (NaAMPS), which is commercially available. A 52 48 ( w/ w) PBZT/HAMPS homopolymer blend was prepared by co-dissolving the components in methanesulphonic acid. Upon precipitation in cold water, the molecular composite was obtained as an orange-yellow fibre, which became red when it was dry. This solid-state chromatic variability is reversible and was observed when the blend (polymer pulp or coagulated film) was immersed in a variety of organic solvents. In addition, coagulated film showed relatively little lateral shrinkage after vacuum drying at 110°C overnight and no phase-separated morphology was detected by scanning electron microscopy within 500 Å resolution.

上顎総義歯におけるポリサルホン樹脂とポリカーボネート樹脂の成形による変形

Maxillary complete dentures were constructed with reinforcing polysulfon resin by the compression molding, reinforcing polycarbonate resin by the injection molding and polymethylmetacrylate resin.The deformation from the each molding methods were observed in three dimension.The results were comparatively discussed, and the following conclusions were obtained.1. Both in the artifical teeth resion and mucosal surface of alveolar resion, the lateral shrinkage were distinctively observed in the conditions of reinforcing polysulfon resin and reinforcing polycarbonate resin. On the contrary, the even shrinkage and little distortion was observed in the condition of polymethylmetacrylate resin.2. The lateral expansion of denture border in maxillary tuberosity resion were observed in the conditions of reinforcing polysulfon resin and polymethylmetacrylate resin, although the lateral shrinkage of that was observed in the condition of the reinforcing polycarbonate resin.3. The midline of mucosal surface transitted anteriorly in the condition of reinforcing polysulfon resin and reinforcing polycarbonate resin.4. In sagittal direction of the palatal midline, the deformation was the least in the condition of reinforcing polysulfon resin.

Effects of fiber orientation on the stress distribution in model composites

AbstractA Raman‐mechanical technique was used to study the relationship between stress distribution and fiber orientation in model composites. Our experimental data generally were consistent with most simplistic mechanical models. A more complete analysis, using the Eshelby equivalent inclusion method, fitted our experimental data exceptionally well. For large applied strains, compressive failure occurred for fibers which were oriented at high angles relative to the draw direction. This occurred because of the lateral shrinkage associated with the matrix when the sample was stretched. The effect of fiber end geometry on the stress distribution for these misaligned fibers was the same as observed earlier. Tapered‐end fibers generally carried loads more efficiently in composites than blunt‐end fibers.

Reply: Design recommendations for reinforced concrete cylindrical storage structures for aqueous materials

The design of cylindrical non-prestressed concrete storage structures in Ontario does not appear governed by any standard or building code. Many aboveground water storage reservoirs in Ontario have deteriorated badly in a relatively short period of use. Many farm silos suffer from problems similar to those of the water storage reservoirs. This paper is concerned with the selection of the wall thickness and the hoop reinforcement for cylindrical storage tanks and silos for liquids or wet materials where tensile cracking of the concrete is to be limited.Three design criteria are presented. The first limits the circumferential tensile stress in the concrete from lateral wall pressure, shrinkage, and temperature gradients in the wall. The second is concerned with the tension in the hoop reinforcement and guards against collapse. The third limits the crack widths of the cracked concrete section. The most important design loads are discussed. Maximum values for hoop tension are provided for liquid pressures. A ...

The effect of ion implantation on polymer mask resistance to ion beam etching

The effect of Ar + ion implantation with energy of 150 keV (doses 10 114−10 16 ions cm −2) into negative EN-14 electron resists on their resistance to subsequent ion-beam etching by argon ions has been investigated. Studies of structural reconstructions in resist films using the method of infrared spectroscopy show a significant change in the character of the infrared spectra after ion-beam implantation due to an increase in the atomic binding energy in the modified resist. This leads to a great reduction of the etch rate of modified resist layer (a factor of three reduction at doses of 10 15 ions cm −2). A decrease in resist film thickness is also observed. The simultaneous effect of these two factors is that the resulting resistance of modified resist masks to ion-beam etching does not increase. However, application of resist masks with a reduced etch rate modified by ion implantation permits one to decrease the lateral shrinkage of the etched structures and to increase the precision of the ion-beam etch process.

Design recommendations for reinforced concrete cylindrical storage structures for aqueous materials

The design of cylindrical non-prestressed concrete storage structures in Ontario does not appear governed by any standard or building code. Many aboveground water storage reservoirs in Ontario have deteriorated badly in a relatively short period of use. Many farm silos suffer from problems similar to those of the water storage reservoirs. This paper is concerned with the selection of the wall thickness and the hoop reinforcement for cylindrical storage tanks and silos for liquids or wet materials where tensile cracking of the concrete is to be limited.Three design criteria are presented. The first limits the circumferential tensile stress in the concrete from lateral wall pressure, shrinkage, and temperature gradients in the wall. The second is concerned with the tension in the hoop reinforcement and guards against collapse. The third limits the crack widths of the cracked concrete section. The most important design loads are discussed. Maximum values for hoop tension are provided for liquid pressures. A design temperature gradient of 15 °C is recommended for design in southern Ontario. As well, appropriate values of shrinkage tensile stress are suggested. The collapse limit state criterion must be evaluated for the hoop steel stresses due to the lateral wall loads. The limit state criterion related to the hoop tensile stress in the concrete must be investigated for all possible load combinations of lateral wall load, shrinkage, and temperature gradients. Reasonable load combination factors have been recommended. Recommendations on the tensile strength of concrete and on appropriate strength factors have been made. Key words: cylindrical tank, design criteria, hoop stresses, reinforced concrete, silo, standpipe, storage of liquids, storage of saturated bulk materials.

TaSi2gate for VLSI CMOS circuits

It is shown, that lateral shrinkage of 2-µm CMOS devices and reduction of the gate oxide thickness to about 20 nm is significantly facilitated by replacing the n+-poly-Si or polycide gates by TaSi 2 . Due to its higher work function, TaSi 2 allows the simultaneous reduction of the channel doping in the n-channel and the charge compensation in the p-channel without changing the threshold voltages. Thus compared with n+-poly-Si gate n-channel transistors substrate sensitivity and substrate current are reduced, and low-level breakdown strength is raised. In p-channel transistors, the subthreshold current behavior and U T (L)-dependence are improved. Consequently, the channel length of both n- and p-channel transistors can be reduced by about 0.5 µm without significant degradation. The MOS characteristics N ss , flatband and threshold voltage stability, and dielectric strength appear similar for TaSi 2 and n + -poly Si gate transistors.

Lateral shrinkage of the myofilament lattice in chemically skinned muscles during contraction.

A toe muscle was isolated from a hind limb of the mouse and treated with saponin to make the sarcolemma more permeable to the solutes of the bathing medium. The equatorial X-ray diffraction pattern was recorded to determine the 1,0 spacing of the hexagonal myofilament lattice. The spacing in relaxed muscle at a sarcomere length of 2.5 microns was 408 A. When the muscle was maximally activated at pCa 4.4, a steady isometric tension of 1.3 kg/cm2 was produced and the spacing decreased to 384 A. A decrease in spacing of the same magnitude was observed when a relaxed muscle went into rigor, although the rigor tension was only 0.1 kg/cm2, 8% of the maximum contractile tension. From the intensity ratio of the 1,0 and 1,1 reflections the number of myosin heads transferred radially to the vicinity of the thin filament was calculated. During the maximum activation at pCa 4.4 the amount of the radial transfer was 96% of that in rigor. When the muscle was activated at a lower calcium concentration, the lattice shrinkage was smaller and the radial transfer was also smaller. These findings suggest that the lateral force underlying the lattice shrinkage may be due to lateral elasticity of cross-bridges.

The kinetics of bidirectional growth of stem sections from etiolated pea seedlings in response to acid, auxin and fusicoccin

Growth in length and diameter of abraded stem sections from etiolated pea (Pisum sativum L.) seedlings was monitored continuously using a double laser optical level auxanometer system. Acidic solutions (pH 4.0-4.5) induced rapid elongation accompanied by lateral shrinkage (up to 8% of the initial diameter). The shrinkage phase lasted for 30-45 min. Pretreatment with permeant solutes (KCl, NaCl, sucrose or glucose) prevented lateral shrinkage, while pretreatment with the impermeant solute, polyethylene glycol, did not block lateral contraction in response to acid. A slight turgor step-up given during the shrinkage phase inhibited lateral shrinkage and increased the elongation rate. Visual observation confirmed that shrinkage occurred and that the same region of the stem that contracted in diameter also elongated. It is proposed that lateral shrinkage results from a decrease in turgor pressure during acid-stimulated elongation. Elongation induced by auxin and fusicoccin (FC) was also accompanied by a decrease in the diameter; this decrease could be prevented by pretreatment with KCl or glucose. Thus, the early phase of auxin and FC action is "acid-like". However, the shrinkage is of shorter duration (14-20 min) and it is less drastic (ca. 2%). In addition, FC caused lateral expansion after a 20-min lag period in stems pretreated with KCl. The results are consistent with an acid-growth mechanism during the early phase (first 20-40 min) of the responses to both auxin and FC. It is suggested that enhanced osmoregulation subsequently inhibits further lateral shrinkage and helps to maintain steady-state growth. FC, unlike auxin, may alter the anisotropic character of the wall.

Isothermal growth, thickening, and melting of poly(ethylene oxide) single crystals in the bulk

AbstractCharacteristic features of isothermal growth, thickening, and melting behavior of melt grown single crystals of low molecular weight poly (ethylene oxide) fractions are presented and discussed in terms of their relevance to basic concepts of polymer crystal growth. Measurements of growth (G) and thickening rates of once folded chain crystals were extended (up to the melting point) into a temperature range where usually only extended chain crystals grow. Monolayer extended and folded chain crystals melt by lateral shrinkage, the rate of which (G−) depends not only on temperature, but also on thermal history. G− increases exponentially with the degree of superheating, and the value of the temperature coefficient d log G−/dT is proportional to the lamellar thickness. In the narrow temperature interval where transition from once folded to extended chain growth occurs, the crystal morphology displays some spectacular features. These may be accounted for in terms of the crystal habit and the rate of completion, g. of a molecular layer in the particular (hk0) prism face considered. Morphological analysis shows that g is of the same order of magnitude as G(hkO), leading to the conclusion that the growth of these PEO crystals is controlled by multiple surface nucleation rather than by deposition of a single surface nucleus.

Estimation of plant water status with the beta-gauge

The β-gauge is a useful instrument for monitoring changes in plant water status, and it has also been used to estimate absolute water status. The effects of plant parameters such as variability of leaves, lateral leaf shrinkage, growth and ontogenetic changes, on the use of the technique for water status estimation in cotton were examined. It was concluded that the method has limited utility for the estimation of absolute plant water status. In conjunction, however, with a parallel sampling technique which was developed, the method can be of value for following both long and short term changes in water status.