Considerable Shrinkage Research Articles

A large Cirroteuthis magna (Cephalopoda: Cirroctopoda) caught on the Cape Verde Terrace (North Atlantic)

A large, mature, female cirrate octopod, Cirroteuthis magna, was caught in a research trawl at 3200-m depth on the Cape Verde Terrace off the west African coast in November 1999. It is only the fourth recorded specimen of this species and the largest specimen (1,700 mm TL; 330 mm ML) of cirrate octopod ever caught. Detailed measurements were taken of the fresh and preserved specimen and indicated considerable shrinkage (17–32%) during formalin preservation. Careful dissection revealed large mature eggs (12·5–14 mm long) in the proximal oviduct, and a wide range of egg sizes and development stages in the ovary. The taxonomy and ecology of the species is briefly discussed.

High-pressure NMR study of cis-1,n-disubstituted[n]paracyclophanes. Effect of increased pressure on the hindered internal rotation.

The effect of hydrostatic pressure on the rate of internal rotation of title compounds has been examined by the DNMR method. Quartz pressure-resisting NMR cells were used to realize the high-pressure experiments up to 390 (line shape measurements) and 450 MPa (chemical shift measurements). Application of hydrostatic pressure was found to accelerate the rotation of the benzene ring, while pressure-induced low-frequency chemical shifts of bridge methylene protons indicated that there is a considerable shrinkage of the methylene bridge structure upon pressurization.

Atomic Force Microscopic Study of the Human Cornea Following Excimer Laser Keratectomy

The aim of this study was to examine the corneal surface structures with a new investigative method, the atomic force microscope following 193 nm excimer laser photoablation. Fresh human corneas were irradiated in vitro with an increasing number of impulses emitted by a 193 nm ArF laboratory excimer laser in order to produce either smooth flat surfaces or stair-like formations within the cornea. The corneas were investigated in a Topometrix® atomic force microscope in their native state. For comparison, three corneas were fixed with glutaraldehyde and processed for scanning electron microscopy.Atomic force microscopy and scanning electron microscopy revealed the same surface characteristics of photoablated corneas, though the preparation for scanning electron microscopy induced considerable shrinkage of the tissues. The layers of the cornea could be distinguished from each other and deeper ablations of the stroma produced a rougher surface. On the lateral walls of ablated stairs small droplets of ejected material could be seen with scanning electron microscope.Atomic force microscope produces three-dimensional images of the scanned native corneal surfaces and it could be a valuable tool to investigate the corneal smoothness. Our investigations have provided similar results as those obtained with scanning electron microscopy showing that the laser-ablated corneal surface remains relatively smooth. We suggest that the formation of condense droplets of ejected materials is based on hydrodynamic motions induced by boiling water solutions.

Augmentation of calvarial tissue using non-permeable silicone domes and bovine bone mineral. An experimental study in the rat.

The aim of the present study was to evaluate the effect of bovine bone mineral placement as an adjunct to a guided bone regeneration (GBR)-barrier in experimental bone augmentation. Some 18 Sprague-Dawley rats underwent flap surgery in which non-permeable silicone domes were placed on the calvaria. A test group of 9 animals received domes filled with cancellous deproteinized bovine bone mineral (Bio-Oss). The domes of 9 control animals were left empty. The experiment was terminated after 8 weeks of healing. Inspection after histologic preparation found no signs of any foreign body reaction to the implanted bovine bone mineral, which seemed to be well integrated with the augmented tissue. The control specimens healed uniformly with new bone inside the domes at the base of the calvaria. The tissue inside the domes of the test specimens had a completely different architecture with new bone both at the base of the calvaria and at a distance from the base, surrounded by and in close contact with non-mineralized tissue and remaining bovine bone mineral. Some ingrowth of soft connective tissue, most likely from the sagittal skull suture could be seen in most test and control specimens. Histomorphometric analysis revealed that the total amount of augmented tissue was significantly greater in the test group (x = 1.93 +/- 0.21 mm2) than in the control group (x = 0.99 +/- 0.22 mm2), P < 0.001). The control domes contained 0.73 +/- 0.28 mm2 augmented bone, while the corresponding value for the test specimens was 0.35 +/- 0.13 mm2, significantly less than the controls (P < 0.01). The test domes contained 0.83 +/- 0.15 mm2 newly-formed non-mineralized calvarial tissue, significantly more than the controls (x = 0.26 +/- 0.16 mm2), P < 0.001). Remaining particles of bovine bone mineral constituted 0.76 +/- 0.14 mm2, or 39%, of the total amount of augmented tissue in the test group. A considerable shrinkage to about 69% of the height of the initial fill of bovine bone mineral at surgery appeared in the test domes after 8 weeks of healing. The reason for this was probably more due to a denser packing of the bovine bone mineral during healing than to resorptive activity. It was concluded that implantation of bovine bone mineral combined with GBR technique significantly enhances augmentation of calvarial tissue. Early mineralization, however, seems to be retarded compared to non-filled control specimens. Further studies should be made to determine the long-term maturation of augmented tissue including resorption pattern of the bovine bone mineral.

EFFECTIVE DIFFUSION COEFFICIENT OF ACTIVE SOLVENTS IN COMPOSITE POLYMERIC MATERIALS

ABSTRACT A method and a device for determination of the effective diffusion coefficient of active solvents in composite polymeric materials (CPM) based on cellulose derivatives are proposed and examined. This method accounts for anomalous mass transfer phenomena, considerable shrinkage and changes of sorption capacity of the CPM specimen allowing selection of the rational technological regime. Results of experimental studies on diffusion of acetone and ethanol in cellulose nitrate with various degrees of substitution are given as examples.

A study on laser sintering of Fe-Cu powder compacts

The sintering of Fe-Cu powder compacts by laser beams was studied to determine densification and microstructural development. The influence of processing variables such as Cu content, laser output power, sintering time, and green density on the densification and Brinell hardness (HB) were analyzed, and several temperature curves measured during laser sintering (LS) were also discussed in this article. After LS, the samples exhibited considerable shrinkage, which was very different from the effects of conventional sintering (CS). The main reasons for shrinkage are the laser’s very fast heating rates, short sintering times, and relatively high sintering temperatures. As a consequence, insufficient time is available for Fe particles to diffuse in the solid state to form a rigid skeleton. After formation, the liquid penetrates quickly along boundaries and separates the Fe particles, leading to rapid collapse and particle rearrangement, which finally results in considerable shrinkage. An increased Cu content, laser output power, and sintering time can promote shrinkage and hardness, but compact slumping occurs when the laser power is too high.

Effect of measurement error on energy-adjustment models in nutritional epidemiology.

The use and interpretation of energy-adjustment regression models in nutritional epidemiology has been vigorously debated recently. There has been little discussion, however, regarding the effect of dietary measurement error on the performance of such models. Contrary to conventional assumptions invoked in the standard treatment of the effect of measurement error in regression analysis, reporting errors in dietary studies are usually biased, correlated with true nutrient intakes and with each other, heteroscedastic, and nonnormally distributed. Methods developed in this paper allow for this more complex error structure and are therefore more appropriate for dietary data. For practical illustration, these methods are applied to data from the Women's Health Trial Vanguard Study. The results demonstrate considerable shrinkage in the magnitude of the estimated main exposure effect in energy-adjustment models due to attenuation of the true effect and contamination from the effect of an adjusting covariate. In most cases, this shrinkage causes a sharply reduced statistical power of the corresponding significance test in comparison with measurement without error. These results emphasize the need to understand the measurement error properties of dietary instruments through validation/calibration studies and, where possible, to correct for the impact of measurement error when applying energy-adjustment models.

Phase-Separated Inorganic-Organic Hybrids for Microelectronic Applications

As on-chip device densities increase and active device dimensions shrink, signal delays and noise increase due to capacitive coupling and crosstalk between the metal interconnections. Since delays, noise, and power consumption all depend critically on the dielectric constant of the separating insulator, much attention has focused recently on replacing standard silicon dioxide with new intermetal dielectrics (IMDs) having dielectric constants considerably lower than conventional oxide (k = 3.9–4.2). On-chip silicon dioxide insulators are currently deposited by gas-phase techniques such as chemical vapor deposition or plasma-enhanced chemical vapor deposition. Silicate films may also be formed at lower temperatures by sol-gel procedures. In the sol-gel process, typically an orthosilicate ester is hydrolyzed with water. This often occurs in an organic solvent to form a soluble, partially condensed polymer (sol) that can be spun on a substrate to produce a solvent-containing film. Subsequent solvent removal and curing results in the silicate film. The process involves hydrolysis to generate polyfunctional silanols followed by condensation polymerization to eventually yield a gel. Since both processes involve the substantial loss of volatile materials, considerable shrinkage occurs (75–85% is typical). Inhomogeneity of shrinkage or shrinkage on constraining substrates can often lead to cracking unless the films are very thin (often &lt;1 μm). In the sol-gel process, a variety of techniques are employed to avoid capillary-driven cracking forces, including (1) very slow drying, (2) drying with supercritical fluids, or (3) chemically controlled condensation.

Effect of thyroid hormones on neurosecretory cells of supraoptic and paraventricular nuclei of rat hypothalamusin vitro

The direct effect of thyroid hormones on oxytocin-and vasopressinergic cells is studiedin vitro on cultured slices of rat hypothalamus containing the paraventricular and/or supraoptic nuclei. It is shown that 30- and 60-min exposure to thyroxine leads to considerable shrinkage of the nucleoli of oxytocin-and vasopressin-secreting cells in the supraoptic and paraventricular nuclei, which reflects the decrease in their functional activity. The addition of triiodothyronine leads to stimulation of neurosecretory cells (30-min incubation) followed by a drop in their functional activity.

Chronic treatment with CV 205-502 restores the gonadal function in hyperprolactinemic males.

The aim of this study was to evaluate the effects of a chronic treatment with the non-ergot-derived dopamine agonist quinagolide (CV 205-502) on sexual and gonadal function in hyperprolactinemic males. Thirteen males with macroprolactinoma and one with microprolactinoma were treated with CV 205-502 at the dose of 0.15-0.6 mg/day for 6-24 months. Baseline prolactin (PRL) was 464 +/- 75.7 microg/l. All the patients suffered from libido impairment, five of reduced sexual potency, six had infertility and in four bilateral induced galactorrhea was shown. The semen analysis revealed a severe oligoasthenospermia with reduced sperm count, motility and forward progression, with an abnormal morphology and decreased viability. A significant reduction of serum PRL levels (nadir PRL = 12.3 +/- 5.4 microg/l) was obtained during the treatment. Normalization of prolactinemia was reached in 13 of the 14 patients after 3 months. After 1 year, a significant improvement of sperm parameters, in terms of increase of number (from 5600 +/- 111 to 20,564 +/- 587 mm3), motility at 1 h (from 24.8 +/- 0.1 to 52.6 +/- 0.5%), forward progression (from 24 +/- 1.4 to 62.3 +/- 2.9%) and normal morphology (from 53.8 +/- 2.5 to 62.2 +/- 2.4%), was recorded. In addition, a significant increase of serum follicle-stimulating hormone (from 5.3 +/- 0.6 to 7.8 +/- 0.4 U/l), luteinizing hormone (from 4.4 +/- 0.5 to 7.7 +/- 0.4 U/l) and testosterone (from 3.4 +/- 0.4 to 4.7 +/- 0.2 microg/l) was recorded. A significant increase of luteinizing hormone (9.4 +/- 0.7 U/l) and testosterone (5.2 +/- 0.4 microg/l), as well as a further improvement of sperm parameters, was found after 2 years of therapy. Sellar computed tomography and/or magnetic resonance showed a considerable shrinkage (> or = 30%) of tumoral mass in 8 out of 13 patients with macroprolacinoma. Side effects were recorded in only one patient. In conclusion, the treatment with CV 205-502 normalizing PRL levels improves gonadal and sexual function and fertility in males with prolactinoma, providing good tolerability and excellent patient compliance to medical treatment. This result demonstrates that the impairment of gonadal function in hyperprolactinemic patients is a functional modification.

Contact Microradiography of Dentine under Wet Conditions to Prevent Lesion Shrinkage

A considerable shrinkage of dentinal lesions is the result of desiccation of dentine sections during contact microradiography. We introduce a simple modification which allows the dentine to be wet during the microradiographic procedure. The volume stability of both sound and demineralized dentine sections microradiographed under wet conditions is compared to sections microradiographed while being exposed to the air. Under wet conditions no shrinkage could be detected of both sound and demineralized sections. Within 15 min exposure to the air, demineralized sections showed their lesion depth to be significantly reduced by 21%, resulting in an underestimation of the mineral loss of 44%. No shrinkage was observed in the air-dried sound dentine. Especially when high-resolution plates are used, which require an extended exposure time, microradiography of dentine sections under wet conditions is recommended. In longitudinal de- and remineralization studies, the use of water instead of impregnation with low-volatility liquids is to be preferred because of the possible effects of these liquids on the mineralization processes.

COMPARISON OF THE PHYSICAL AND CHEMICAL PROPERTIES BETWEEN CONTAINER-GROWN WOODY ORNAMENTALS

Kenaf (Hibiscus cannabinus) is an alternative fiber crop being grown in Mississippi that maybe used as a tree-less fiber substitute for making paper. A by-product in this process is the pithy light-weight fiber core. The objective of this study was to examine the chemical and physical properties of kenaf fiber core as a medium component in growing woody ornamentals and compare to pine bark. Comparisons of media in which Ilex crenata `Cherokee' and Rhodoendron eirocarpum `Wakabuisi' were grown were made. The physical and chemical properties including bulk density, total pore space, water retention, pH and soluble salt concentrations were determined. Aged kenaf had lower pH values than fresh and both aged and fresh kenaf had higher pH values than pine bark. The total pore space of kenaf was lower than the pore space of pine bark. At the termination of the study, the kenaf media had considerable shrinkage, which was considered unsuitable for a long-term crop.

Optimization of Reservoir Shrinkage Volumes:Laboratory And Field Results

Abstract This paper reviews a technique to enhance the value of existing oil fields by optimizing the operating temperature and pressure of the surface processing facilities (batteries). Incremental value is added by reducing the shrinkage volume and density of the stock tank oil, which is offset to some extent by reduced gas production volumes and heat content. Improved laboratory equipment and procedures were assembled to model multi-stage separation systems. The experimental and theoretical results determined the optimum operating conditions and an economic evaluation was done which identified outstanding potential economic returns. A post mortem evaluation indicated that the project has performed as expected, with significant increases in both incremental cash flow and field value. Introduction With increasing economic pressures placed on the upstream oil industry, One must take advantage of every means possible to extract the greatest economic value from existing oil fields. One prospective means of doing so, where oil shrinkage volumes are reduced by modifying surface facility temperatures and pressures, may hold considerable promise. This method applies best to conventional and light oils with an API gravity of at least 35 °. Background An obvious method of increasing revenues from an oil-producing property is to maximize the sales liquid volumes and minimize the sales liquid density (while maintaining the appropriate RVP criterion) with respect to unit volume of reservoir fluid produced at the well head. The lighter the oil the more sensitive the oil's shrinkage response will be to the conditions chosen between the well head and the stock tank. For some oils the volume may only shrink by 1 % in travelling through the separator train to the stock tank. For lighter oils, however, the shrinkage may be more than 10 % and therefore considerable revenue could be realized if this shrinkage could be reduced. Figure 1 shows a typical separation train. For mature waterfloods and miscible floods, the conditions of the Inter Surge Vessel are usually determined by the volume of f1uids being produced since the temperature, in particular, is very difficult to change due to the large volume of water being produced and its relatively high heat capacity. Pressures are more easy to modify but their impact on volumes is usually less important than temperature. In combination, the two may act synergistically, however, resulting in considerable shrinkage changes. FIGURE 1: Typical surface processing operations. (Available in full paper) Two oil systems have been tested in the laboratory using specially designed equipment to measure accurate phase volumes. This will be reviewed in detail along with all the experimental data generated. The scheme was then implemented in the field and detailed economic analyses were performed to determine the impact on cash flow and field net present value. Laboratory Testing Figure 2 provides a schematic diagram of the pressure cells used most commonly to measure PVT behavior of petroleum fluids. The cell is a Ruska-type visual cell with an internal diameter of approximately 3.6 cm (1.4 inches) and a length of about 10 cm (4 inches).

Refrigerated muscle used to bridge nerve defects

Bridging of nerve defects with muscle tissue is usually done with deep frozen grafts. The method has the disadvantage of considerable shrinkage and stiffening of the graft, as well as devitalization of the structures accompanying muscle fibers. As an alternative method an experiment on rats was done to test the use of refrigerated grafts, which do not have those disadvantages. The morphological evidence was that refrigerated grafts give as least as good results as deep frozen grafts.

Atypical radical liver resection in hepatoblastoma

Five consecutive patients (age at presentation 2 1/2–30 months) with hepatoblastoma during a 4-year period are reported. The youngest died due to uncontrolled spontaneous hepatic bleeding prior to any treatment. After considerable tumor shrinkage was achieved by preoperative combined chemotherapy (doxorubicin and cisplatinum), an atypical liver resection with ultrasound knife equipment (USK) was successfully carried out in four patients, all of whom were discharged from the pediatric surgical department free of symptoms on 4th to 10th postoperative day. No recurrences and no tumor metastases occurred following the completion of postoperative chemotherapy. Atypical liver resection with USK is a safe surgical modality that allows the liver parenchyma to be crushed while leaving the bile ducts and vessels intact. These structures can be identified and divided separately. Complete tumor removal from the parenchyma can be performed radically regardless of the surgical resectability as defined by the anatomic borders of the liver segments.

The preparation and characterization of sol-gel silica spheres

Abstract Silica sol-gel spherical bodies are prepared containing 2–13 wt% SiO 2 in water. The silica sol is prepared by addition of a sodium silicate solution to a dilute nitric acid solution. The silica sol thus obtained is introduced dropwise into hot paraffin oil, which results in spherical hydrogel bodies. The pore volume of the spheres is varied between 0.16 and 1.4 ml/g, and the pore radii between 0.8 and 60 nm. The pore structure of the hydrogels is investigated by thermoporometry. The hydrogels are washed and dried at 293, 333 and 393 K. The pore structure is the dried spheres is determined by nitrogen adsorption and desorption at 77 K. Drying causes a considerable shrinkage of the pore dimensions. The pore radius of the sample containing 2 wt% SiO 2 in water diminishes from 10.2 to 2.9 nm, while the pore volume decreases from 0.9 to 0.5 ml/g. Drying the gelled spheres at temperatures > 293 K leads to a lower shrinkage, and consequently to a higher pore volume of the dried spheres. The pore structure of both xerogel and hydrogel spheres is modified by means of a hydrothermal treatment. Hydrothermal treatment of the hydrogel spheres increases the pore volume, whereas that of the xerogel spheres remains constant. Differences observed with the hydrothermally aged hydrogel and xerogel spheres are attributed to the ripening mechanism being dependent on the initial pore structure.

Kinetic instability in reaction-diffusion systems: the effect of time delay

The effects of time delay on the transition curve marking the onset of kinetic instability in a class of reaction-diffusion systems are analytically evaluated by linearizing the system equations. The analysis in general shows that the transition curves become multivalued and indicates considerable shrinkage of the parameter plane where such transitions can occur. Also, the effect is more severe for higher extents of time delay.

Freezing gels

The process of freezing of liquid in the pores of a gel is examined in detail. Gels typically begin to freeze at a small undercooling, which indicates that nucleation occurs by a heterogeneous, rather than a homogeneous, mechanism. If a crystal appears in excess liquid at the surface of a porous body, it will penetrate smaller and smaller pores as the temperature is decreased. However, if the pores are small, before the undercooling is great enough to permit penetration, there is a strong driving force for liquid to flow out of the pores to the crystal. It is shown that this creates a gradient in the pressure in the pore liquid, and produces stresses strictly analogous to those generated during evaporative drying. Therefore, cracking can occur during freezing; indeed, freezing stresses can make freezeng-drying even more damaging than conventional drying. Considerable shrinkage can occur as liquid drains from the pores to the growing crystal, and this has important consequences for the measurement of pore size distributions by thermoporometry. The pore sizes may be understimated by ∼ 30% for a typical silica gel, if water is the liquid in the pores. Since the stresses are related to the entropy of fusion and crystal/liquid interfacial energy, organic liquids offer advantages over water for both freeze-drying and thermoporometry. The stress exerted on the network by a crystal is analyzed and a criterion for fracture of the network is presented. An analysis is presented of the kinetics of heterogeneous nucleation when the network itself acts as a nucleation catalyst; in this case, the crystals are expected to appear at nodes in the network. However nucleation by the network is not expected in most material systems.

Distortions in two-dimensional visual space perception in strabismic observers

Amblyopic subjects were asked to memorize circles of different radii (2, 4 and 6°), and then to reconstruct them monocularly with each eye, point by point (12 points per circle). The resulting two-dimensional maps of visual space showed considerable distortions, including expansion, shrinkage and torsion of specific regions of the visual field of the amblyopic eye, but not the normal eye. Based on the differences between the two eyes, we computed complex two-dimensional patterns (gratings, checkerboards, optotypes, written text, natural scenes) as “seen” monocularly with the amblyopic eye. These reconstructed patterns were then compared with drawings of the same patterns observed through the amblyopic eyes of the same subjects. The reconstructed patterns only partially reflected the actual perception for the amblyopic eyes. The compensation of complex, globally-extended scenes in comparison to the distortions obtained by local, punctate settings probably reflects cooperative interactions occurring at higher brain levels.

A synchrotron X‐ray study of the changes occurring in the corneal stroma during processing for electron microscopy

Using a high-intensity synchroton X-ray source, the structural changes occurring in the corneal stroma were monitored during each stage of several different processing runs for the transmission electron microscope (TEM) and scanning electron microscope (SEM). The parameters studied were interfibrillar spacing, intermolecular spacing, D-periodicity and fibril diameter. The processing schedule that produced the least changes in spacings for TEM specimens involved extended fixation in glutaraldehyde followed by low-temperature embedding in Lowicryl K4M resin. However, interfibrillar material was better preserved after embedding in LR White resin or Nanoplast. Almost every processing stage for electron microscopy produced significant changes in one or more structural parameters in the cornea. Glutaraldehyde fixation significantly increased the intermolecular spacings, while resin infiltration and resin polymerization each resulted in shrinkage of all the spacings monitored. Critical-point drying for SEM specimens resulted in considerable shrinkage in all three spacings, but was still preferable to air drying, which caused reduction in the order of the fibril packing, resulting in loss of the interfibrillar X-ray pattern. Perhaps the most drastic effect was caused by post-fixation in osmium tetroxide, which resulted in loss of the intermolecular pattern, and also increased the amount of shrinkage in the interfibrillar spacings and the D-periodicity which occurred during later stages of processing.