Slight Shrinkage Research Articles

Investigations for the Surface of the Oxide Semiconductor Changes by Reduction**Supported by the Far East University Research Foundation under Grant No FEU2013S03, and the Hansung University.

Oxide semiconductor SrTiO3 single crystals are exposed to a reducing atmosphere H2/N2 to induce the reduction of Ti4+ to Ti3+ and the release of oxygen from the lattice compensating the reduction of the Ti ions. In a reducing atmosphere H2/N2 the optical edge brings about a red shift. The infrared reflection spectra suggest that the (11) STO single crystal surface can be terminated by the domain of the SrO or TiO2 alternative layer during the reduction. The anisotropy and asymmetry of optical second-harmonic intensity explain a slight shrinkage. The dielectric constant reaches about 6000 and shows almost frequency dependence at all temperatures. With the increasing temperature, the dielectric constant increases rapidly. The high temperature region and low temperature region have activation energies of 0.89 and 1.04, respectively.

Effect of Spark Plasma Sintering Temperature on Electrochemical Properties of La0.82Mg0.18Ni3.50Co0.15 Alloy

Electrochemical properties of La0.82 Mg0.18 Ni3.50 Co0.15 alloys synthesized by spark plasma sintering (SPS) were investigated based on the electrochemical measurements, physical parameters and microstructure observation. The sintering behavior of La0.82 Mg0.18 Ni3.50 Co0.13 alloys at the temperatures of 900, 950 and 1000 °C is characterized by four stages, i.e., initial slight shrinkage, expansion, abrupt shrinkage and slight expansion. The maximum shrinkage displacement increases with increasing sintering temperature. All of the alloys consist of (La, Mg)2 (Ni, Co)7 phase; additionally, temperatures of 900 and 950 °C are beneficial to the formation of (La, Mg) (Ni, Co)3 phase, whereas the LaNi5 phase is easy to form in the alloy synthesized by SPS at 1000 °C. The electrochemical measurements indicate an evident change of the electrochemical performance of the alloys associated with increasing the sintering temperature. The discharge capacity of the alloys first increases and then decreases as sintering temperature rises, whereas their cycle stability clearly grows all the time. Furthermore, the charging-discharging potential difference and discharging efficiency both demonstrate that the electrochemical properties of the alloy electrodes first augment and then decline with increasing sintering temperature.

Performance Evaluation of a Plastic Foundation for Sewage Pipeline

Abstract Earth pressure (i.e., the overburden pressure caused by hydraulic pressure and vehicle traffic loads) affects sewage pipelines. In particular, backfill materials and the execution of works considerably affect the amount of damage to sewage pipelines. A plastic foundation has been developed to reduce this damage. The load-deformation test results obtained using a universal testing machine show that the load of a rigid concrete pipe (a typical rigid pipe) increased when the contact angle of the lightweight plastic foundation increased. When the contact angle was 135°, as in case A1 in this study, 4.1 tons and 3.4 tons were measured at the sockets and pipe body, respectively. For a contact angle of 90° (case A2), the destructive strength was measured as 3.7 tons at the sockets and 2.9 tons at the pipe body. Overall, the deformation of the pipe resulted in tensile strain in the diametrical direction, and slight shrinkage occurred in the longitudinal direction of the pipe as a result of loading on a prefabricated lightweight plastic foundation. For the foundation of the polyethylene triple-wall corrugated pipe, 100 % new plastic was used for case B1, whereas 50 % recycled plastic was used for case B2. The results show that 1.49 tons were observed at 5 % of pipe strain for case B1, whereas 1.35 tons were observed at 5 % of pipe strain for case B2. The recycled plastic foundation showed a tendency to somewhat reduce the load relative to the foundation that consisted of original materials. The results of destructive strength tests on a plastic foundation show that case B1 featured 13.78 tons of loading and 5.16 mm of deformation, whereas case B2 showed 9.66 tons of loading and 5.41 mm of deformation.

Investigation of spin-phonon coupling in triangular-lattice antiferromagnet AgCrS2 by infrared transmission spectroscopy

In this work, we have investigated the spin-phonon coupling in the triangular-lattice antiferromagnet AgCrS2 by means of infrared transmission spectroscopy. At 300K, four IR active phonon modes having the typical profile expected for an insulating material have been observed. These phonon modes are found to continuously harden upon cooling due to the slight shrinkage of the lattice. The splitting of a phonon mode and the occurrence of two new phonon modes are observed at TN, providing evidences for strong spin-phonon coupling. It is noted that phonon eigenfrequencies show significant deviations from the anharmonic contribution at temperatures much higher than TN, which is clearly determined by the strong spin fluctuations. Our results suggest that spin-phonon coupling has strong influence even in PM state in this material.

Influence of Chemical Admixtures on Properties of Alkali-Activated Slag-Based Mortars

Alkali-activated slag (AAS) based binders can have similar or even better properties in terms of mechanical performance, durability and chemical resistance than ordinary Portland cement (PC), but AAS binders also show some drawbacks, especially high shrinkage and poor rheology. Improvement of these features in the case of PC binder is well established, but a lot of conventional admixtures like superplasticizers do not work in AAS. The influence of shrinkage reducing admixture (SRA) and airentraining admixture (AEA) on mechanical properties, workability and shrinkage was investigated in this study. These admixtures were used in the different dosages in the range of 0–2.0% (by mass of slag). With increasing content of both admixtures compressive and flexural strength decreased. Similar effect was observed for workability. On the other hand, promising results in respect of shrinkage reduction were obtained particularly for SRA, where its 1.0% dose reduced drying shrinkage of the reference mortar by more than 70%. Only slight shrinkage reduction was observed for 0.50% of AEA.

Primary cerebellopontine angle ependymoma with spinal metastasis in an adult patient: A case report.

Subtentorial ependymoma is a common central nervous system tumor in young children, but is uncommon in adults. Ependymoma often arises from the cells lining the fourth ventricle. The present study reports a rare case of primary ependymoma that originated from the cerebellopontine angle, with local extension to the two internal auditory canals and remote spinal metastasis, in an adult male. A 50-year-old male presented with headache, tinnitus and bilateral hearing loss that had persisted for 4 months. Magnetic resonance imaging (MRI) revealed a mass in each of the cerebellopontine angles, which had spread to each internal auditory canal and wrapped the VII/VIII cranial nerve complex. A gross total resection was performed to remove the mass in the right side. Histological examination confirmed that the tumor was a World Health Organization grade II papillary ependymoma. Notably, the patient complained of urine retention post-surgery and massive occupational lesions in T3-T4 and L5-S2 were found on full spinal cord MRI. The patient then received combination therapy consisting of temozolomide, and whole-brain and spinal cord radiation. In the final follow-up examination, performed 13 months after treatment, slight shrinkage of the T3 lesion was observed, and no progression of the left cerebellopontine angle and S5-L2 lesions were identified on MRI. In summary, although this clinical entity is rare, the diagnosis of ependymoma and the possibility of spinal cord metastasis should be considered in subtentorial tumors.

Size class structure, growth rates, and orientation of the central Andean cushion Azorella compacta.

Azorella compacta (llareta; Apiaceae) forms dense, woody, cushions and characterizes the high elevation rocky slopes of the central Andean Altiplano. Field studies of an elevational gradient of A. compacta within Lauca National Park in northern Chile found a reverse J-shape distribution of size classes of individuals with abundant small plants at all elevations. A new elevational limit for A. compacta was established at 5,250 m. A series of cushions marked 14 years earlier showed either slight shrinkage or small degrees of growth up to 2.2 cm yr−1. Despite their irregularity in growth, cushions of A. compacta show a strong orientation, centered on a north-facing aspect and angle of about 20° from horizontal. This exposure to maximize solar irradiance closely matches previous observations of a population favoring north-facing slopes at a similar angle. Populations of A. compacta appear to be stable, or even expanding, with young plants abundant.

Mutual relation among lattice distortion, Hall effect property and band edge cathodoluminescence of heavily-boron-doped microwave-plasma CVD diamond films homoepitaxially grown on vicinal (001) high-pressure/high-temperature-synthesized Ib substrates

We have investigated properties of heavily-B-doped diamond (HBD) films homoepitaxially grown with boron-to-carbon (B/C) mole ratios ranging from 1000 to 5000ppm in the source gas mainly by using X-Ray diffraction (XRD), cathodoluminescence (CL), and Hall effect measurements. Each HBD layer was deposited on a vicinal (001) substrate of high-pressure/high-temperature synthesized Ib-type diamond with 5° misorientation angle by means of high-power-density microwave-plasma chemical-vapor-deposition method with a source gas composed of 4% CH4 in H2 and H2-diluted B(CH3)3. XRD data indicated that the lattice constant of the B-doped layer slightly decreased for the B/C ratios≤3000ppm while slightly increasing for that of 5000ppm, suggesting that for the latter HBD sample a part of the incorporated B atoms behaved differently from the remaining other B atoms. By contrast the Hall data indicated that all the HBD samples had a degenerate feature only at temperatures well below room temperature (RT), above which a semiconducting feature was evident, and that the density of the degenerate holes steeply increased from 1.3×1019 to 1.2×1021cm−3 with increases in the incorporated B density, [B], from 1.2×1020 to 5.9×1020cm−3. This drastic change in the hole density strongly suggested the presence of a [B]-dependent impurity band. Their evident near-band-edge CL spectra taken at RT and 85K demonstrated that radiative transition features in the HBD layers considerably varied for the B/C ratios studied. The CL peaks were consistently assigned by assuming both the presence of an impurity band and a slight bandgap shrinkage. These observed features are discussed in relation to the energy separation between the low-mobility impurity band assumed and the valence band in the high-quality HBD layer which are not merged in energy.

Physical properties of Zn doped TiO2 thin films with spray pyrolysis technique and its effects in antibacterial activity

Zinc doped Titanium dioxide (TiO2: Zn) thin films were deposited onto glass substrates by the spray pyrolysis technique with the substrate temperature 450°C. The structural, optical, photoluminescence (PL) properties and morphological studies were investigated for the films deposited with various doping concentration (0, 2, 4, 6 and 8at.%) of zinc. The results of X-ray diffraction (XRD) had shown the presence of anatase peak with a strong orientation along (101) plane at 8at.% of Zn-doped TiO2 film. Scanning electron microscopy (SEM) study showed the uniform distribution of grains with porous nature. Atomic force microscopy (AFM) observations indicated the tetragonal shape at 8at.% of Zn-doped TiO2 with the particle size and decrease in surface roughness. The emission at 398nm was observed at the 8at.% of Zn-doped TiO2 thin film. The carrier concentration and Hall mobility was increased with doping. The antibacterial activity was highly yielded for the Zn-doped TiO2 thin films.

Hydrothermal synthesis of sodium vanadium oxide nanorods for gas sensing application

This study represents that a facile and efficient hydrothermal method has been developed for the synthesis of sodium vanadium oxide (Na2V6O16·3H2O) nanobelts with lengths varying from hundreds of nanometres up to a few micrometres, and widths ranging from 80 to 250nm. These Na2V6O16·3H2O nanobelts transform into Na1.08V3O8 nanorods by calcination at 350°C for 3h and this results in a slight shrinkage. This material has been characterized and examined in terms of its gas sensing properties and it was found that the Na1.08V3O8 nanorods exhibit a good sensitivity towards alcohol(s), and acetone at the optimized operating temperature of 260°C. The as-prepared Na1.08V3O8 nanorods displayed a higher sensitivity towards ethanol than pure V2O5 nanobelts and metal oxide-coated/doped V2O5 nanobelts, as a result of the existence of extra Na+ ions and the decreased electronegativity of V ions that can enhance the gas molecule adsorption and hence the sensing performance. Density functional theory (DFT) simulation has also been carried out to understand the sensing mechanism. This study would be useful for developing sodium vanadium oxide nanostructures as potential gas sensor materials.

Near-infrared to visible upconversion in Tm3+ and Yb3+ codoped Lu2O3 nanocrystals synthesized by hydrothermal method.

Lutetium oxide nanocrystals codoped with Tm3+ and Yb3+ have been successfully synthesized via adjusting the pH values of the precursor solution in a hydrothermal method followed by a subsequent calcination process. The samples were systematically characterized by X-ray diffraction, field-emission scanning microscopy, Fourier transform infrared transmittance spectroscopy, and upconversion luminescent spectra. The experimental results show that the pH values of the precursor solution have great effects on the structural, morphological, and upconversion luminescent properties of Lu2O3:2%Yb3+, 0.2%Tm3+ nanocrystals. The as-formed lutetium oxide precursors could transform to cubic Lu2O3 with the same morphology and a slight shrinkage in size after a calcination process. The upconversion emission intensity of Lu2O3:2%Yb3+, 0.2%Tm3+ nanocrystals obtained from the precursor solution with pH = 9 is the strongest. The enhancement of the upconversion luminescence is suggested to be the consequence of reducing the number of OH- groups and the enlarged nanocrystals size. Strong blue and weak red emissions from the prepared nanocrystals were observed under 980 nm laser excitation, which were attributed to the 1G4 --> 3H6 and 1G4 --> 3F4 transitions of Tm3+ ion, respectively.

Hydrothermal Synthesis and Green Luminescent Properties of Lu<SUB>2</SUB>O<SUB>3</SUB>:Yb<SUP>3+</SUP>/Ho<SUP>3+</SUP> Nanocubes

Uniform and dispersive Lu2O3:Yb3+/Ho3+ nanocubes have been successfully synthesized by the hydrothermal process followed by a subsequent calcination at 800 degrees C. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), cathodoluminescence (CL) spectra, as well as lifetimes measurements were utilized to characterize the synthesized phosphors. The as-formed RE(3+)-doped lutetium oxide precursor via the hydrothermal process as a template could transform to RE(3+)-doped Lu2O3 with their original cubic morphology and slight shrinkage in the size after the post-annealing process. The formation mechanism for the lutetium oxide precursor cubes has been proposed. Under the excitation of UV light, 980-nm laser and low-voltage electron-beams, Lu2O3:Yb3+/Ho3+ phosphors all show the characteristic emission of the Ho3+ ion (5F4, 5S2 --> 18 transition) withgreen color, which is easily observed by naked eyes. The corresponding luminescent mechanisms have been discussed. Due to the excellent PL (including up-conversion and down-conversion) properties and CL properties of the Lu2O3:Yb3+/Ho3+ phosphors, they are potentially applicable in fluorescent lamps, up-conversion fluorescent labels and FED devices as an efficient green phosphor.

UV-Imprint Resists Generated from Polymerizable Ionic Liquids and Titania Nanoparticles

Ionic liquids incorporating a polymerizable anion were prepared in a facile manner and used to fabricate stable titania nanoparticle films. The nanotitania was directly patterned by UV imprinting using micrometer size test structures in a polydimethylsiloxane mold. The resulting resist microstructures are resistant to cracking with only slight shrinkage observed for the system made using a hydrophobic ionic liquid. Because ionic liquids with a plethora of different physical and chemical properties can be made (designed) in a facile manner their application in this facile process instead of organic solvents could lead to many new types of functional materials.

Universality and specificity in molecular orientation in anisotropic gels prepared by diffusion method

Molecular orientation in anisotropic gels of chitosan, Curdlan and DNA obtained by dialysis of those aqueous solutions in gelation-inducing solutions was investigated. In this diffusion method (or dialysis method), the gel formation was induced by letting small molecules diffuse in or out of the polymer solutions through the surface. For the gels of DNA and chitosan, the polymer chains aligned perpendicular to the diffusion direction. The same direction of molecular orientation was observed for the Curdlan gel prepared in the dialysis cell. On the other hand, a peculiar nature was observed for the Curdlan gel prepared in the dialysis tube: the molecular orientation was perpendicular to the diffusion direction in the outermost layer of the gel, while the orientation was parallel to the diffusion direction in the inner translucent layer. The orientation parallel to the diffusion direction is attributed to a small deformation of the inner translucent layer caused by a slight shrinkage of the central region after the gel formation. At least near the surface of the gel, the molecular orientation perpendicular to the diffusion direction is a universal characteristic for the gels prepared by the diffusion method.

Consideration of the reasons why dormant buds of trees have evolved extraorgan freezing as an adaptation for winter survival

Dormant buds of larch (Larix kaempferi) exhibit extraorgan freezing, in which extracellular ice crystals are formed in localized areas far from the primordia, as an adaptive response to freezing temperatures. In order to better understand why dormant buds have evolved such a complicated mechanism, the freezing behavior of isolated primordia from dormant buds of larch were examined using cryo-scanning electron microscopy (cryo-SEM) and by freeze-fracture replica electron microscopy (FR-EM). When isolated primordia were slowly frozen (5°C/day), extracellular ice crystals developed within primordia. Thus, isolated primordia serves as a useful model to examine the freezing response of primordia in which extracellular freezing occurs. Slow freezing (5°C/day) of isolated primordia resulted in a much lower survival rate (25% at −30°C) than in intact buds (100% at −30°C). In whole buds, exhibiting extraorgan freezing, cryo-SEM observations indicated that slow freezing to −30°C resulted in deep supercooling with a slight shrinkage of all primordial cells, whereas in isolated primordia, slow freezing to −30°C resulted in intracellular freezing of about half of the cells with other cells exhibiting extracellular freezing with significant shrinkage and deformation. FR-EM of whole buds subjected to slow freezing revealed the formation of intramembrane particle (IMP)-free areas with long rectangular shapes in the plasma membrane of many primordial cells at temperatures lower than −15°C and in a small number of cells in isolated primordia. In isolated primordia, the number of cells exhibiting intracellular freezing, which in most cases did not reveal membrane fracture faces, corresponded to the numbers of cells exhibiting IMP-free areas in whole buds. We speculate that the formation of IMP-free areas in plasma membranes may induce intracellular freezing when extracellular ice crystals have developed within primordial tissues. FR-EM also revealed the formation of fracture-jump lesions only in the plasma membranes of primordial cells of slowly-frozen, isolated primordia. We propose that such fracture-jump lesions are produced not only by osmotic dehydration but also by the deformation of cells due to the presence of extracellular ice crystals within primordial tissues in isolated primordia. The results indicate that the plasma membrane of primordial cells in ecodormant buds of larch are subject to a phase transition that may give rise to intracellular freezing, as well as increased sensitivity to dehydration, when extracellular ice crystals form within primordial tissues. We propose that extraorgan freezing represents a mechanism that prevents the formation of extracellular ice crystals within primordial tissues, thus lowering the risk of intracellular freezing and dehydrative stress.

Atomistic Structure and Ab Initio Electrochemical Properties of Li4Ti5O12 Defect Spinel for Li Ion Batteries

The Li4Ti5O12 defect spinel is a promising anode material for lithium ion batteries because it transforms to/from Li7Ti5O12 with a negligible volume change during charging/discharging. Ab initio calculation is a powerful approach for modern materials design and mechanistic studies. However, the atomistic models of the stoichiometric Li4Ti5O12 and Li7Ti5O12 defect spinel have not been optimized due to the requirements of large unit cells and numerous atomistic arrangements of Li and Ti ions at the 16d sites of the defect spinel. In this study, ab initio calculations were systematically performed and the most energetically favorable full supercell models were constructed for both Li4Ti5O12 and Li7Ti5O12 defect spinel. The equilibrium lattice parameter of Li4Ti5O12 was 8.4257 Å, while a slight lattice shrinkage of 0.77% and an average intercalation voltage of 1.41 V during charging/discharging were obtained. Moreover, the Li4Ti5O12 phase shows insulating property with a wide bandgap of around 2.3 eV, while the Li7Ti5O12 phase exhibits metallic property. All the calculated structural and electrochemical properties agree closely with the experimental findings in literature. Further theoretical studies on the Li4Ti5O12 defect spinel or other defect spinel in general can be realized according to the full supercell models proposed in this study.

Dip pen nanolithography and transfer of ZnO patterns on plastics for large-area flexible optoelectronic applications

This study demonstrates the ability to combine the dip-pen nanolithography patterning of ZnO solutions on a polymer release layer and their subsequent transfer, after heat-treatment, to a flexible substrate. It is found that ink viscosity plays an important role in controlling both the feature size and the total number of the fabricated features. In addition, the role of the dwell time is investigated and it is observed that higher dwell times lead to both larger printed dot sizes and smaller total numbers of fabricated features. Resulting dot size is ranging from 7.2 to 1.9μm as observed using in-situ optical microscopy. Heat treatment is found to lead to a slight shrinkage of the as-deposited patterns due to the coarsening and sintering mechanisms that are active during firing. Then, using a 75kPa pressure and a hot plate set at 190°C for 10min, the fired ZnO patterns are transferred on a flexible polyethylene naphthalate substrate.The ability to effectively transfer high temperature-treated functional nano/micro-patterns on polymer substrates may be proved vital for the development of large-area flexible optoelectronic device applications.

Cavernous sinus hemangioma: A fourteen year single institution experience

Cavernous sinus hemangioma (CSH) is a rare extra-axial vascular neoplasm that accounts for 2% to 3% of all cavernous sinus tumors. Their location, propensity for profuse bleeding during surgery, and relationship to complex neurovascular structures are factors which present difficulty in excising these lesions. The authors describe their experience of 22 patients with CSH over 14years at a tertiary care center. Patients were managed with microsurgical resection using a purely extradural transcavernous approach (13 patients) and with Gamma Knife radiosurgery (GKRS; Elekta AB, Stockholm, Sweden) (nine patients). Retrospective data analysis found headache and visual impairment were the most common presenting complaints, followed by facial hypesthesia and diplopia. All but one patient had complete tumor excision in the surgical series. Transient ophthalmoparesis (complete resolution in 6–8weeks) was the most common surgical complication. In the GKRS group, marked tumor shrinkage (>50% tumor volume reduction) was achieved in two patients, slight shrinkage in five and no change in two patients, with symptom improvement in the majority of patients. To our knowledge, we describe one of the largest series of CSH managed at a single center. Although microsurgical resection using an extradural transcavernous approach is considered the treatment of choice in CSH and allows complete excision with minimal mortality and long-term morbidity, GKRS is an additional tool for treating residual symptomatic lesions or in patients with associated comorbidities making surgical resection unsuitable.

Light-Driven Bending Crystals of Salicylidenephenylethylamines in Enantiomeric and Racemate Forms

The photomechanical bending behavior of chiral crystals composed of S- and R-enantiomers of photochromic N-3,5-di-tert-butylsalicylidene-1-phenylethylamine in enol form [enol-(S)-1 and enol-(R)-1] has been compared with that of achiral crystals of the racemic compound [enol-(rac)-1] of S- and R-enantiomers. Both platelike chiral and achiral crystals, a few millimeters in length, exhibited similar reversible bending upon alternate irradiation with ultraviolet (UV) and visible light. The reversible bending of the achiral enol-(rac)-1 crystal could be repeated over 100 times, while the tip displacement angles of the chiral enol-(S)-1 and enol-(R)-1 crystals gradually decreased with repeated cycles. In situ X-ray measurements revealed that the bending motion of the chiral and achiral crystals was caused by a slight shrinkage of the a and b axes of the unit cell, respectively, corresponding to the long axis of the platelike crystals; shrinkage was induced by the shape change of component salicylidenephenylethy...

A Two-Step Right Hepatic Lobectomy with Portal Vein Ligation for Large Hepatocellular Carcinoma: Rapid Induction of Left-Lobe Regeneration and Clinicopathologic Correlation

The patient is a 56-year-old man with a long history of chronic hepatitis B, who developed multiple hepatocellular carcinomas in the right lobe with invasion of the right anterior portal vein. There was no evidence of tumor involvement in the left lobe or in extrahepatic organs. Given that the patient had advanced hepatocellular carcinoma associated with gross vascular invasion, a two-step liver resection procedure was performed with right portal vein ligation during the first operation and a subsequent right lobectomy of the liver. The stage I portal vein ligation induced a rapid growth of the left and caudate lobes of the liver with a volume increase from 201 to 405.2 mL in 9 days associated with a slight shrinkage of the tumor nodules. The subsequent right lobectomy was successfully done with a complete removal of tumor nodules and a well-compensated liver function. Postoperatively the patient was complicated with Staphylococcus aureus peritonitis, which was controlled eventually. Biopsy of the left lobe of liver revealed severe small- and medium- droplet steatosis, in addition to regenerative changes. In summary, right portal vein ligation with in situ splitting of the liver allows the surgeon to proceed with hepatic resection in cases where portal vein embolization is technically not possible. The increased risk of morbidity and mortality certainly must be weighed when contemplating this approach and is discussed in this report.