Multi-functional magnesium alloys containing interstitial oxygen atoms

A new class of magnesium alloys has been developed by dissolving large amounts of oxygen atoms into a magnesium lattice (Mg-O alloys). The oxygen atoms are supplied by decomposing titanium dioxide nanoparticles in a magnesium melt at 720 °C; the titanium is then completely separated out from the magnesium melt after solidification. The dissolved oxygen atoms are located at the octahedral sites of magnesium, which expand the magnesium lattice. These alloys possess ionic and metallic bonding characteristics, providing outstanding mechanical and functional properties. A Mg-O-Al casting alloy made in this fashion shows superior mechanical performance, chemical resistance to corrosion, and thermal conductivity. Furthermore, a similar Mg-O-Zn wrought alloy shows high elongation to failure (>50%) at room temperature, because the alloy plastically deforms with only multiple slips in the sub-micrometer grains (<300 nm) surrounding the larger grains (~15 μm). The metal/non-metal interstitial alloys are expected to open a new paradigm in commercial alloy design.

Cellular iron uptake, trafficking and metabolism: Key molecules and mechanisms and their roles in disease

Iron is a crucial transition metal for virtually all life. Two major destinations of iron within mammalian cells are the cytosolic iron-storage protein, ferritin, and mitochondria. In mitochondria, iron is utilized in critical anabolic pathways, including: iron-storage in mitochondrial ferritin, heme synthesis, and iron-sulfur cluster (ISC) biogenesis. Although the pathways involved in ISC synthesis in the mitochondria and cytosol have begun to be characterized, many crucial details remain unknown. In this review, we discuss major aspects of the journey of iron from its initial cellular uptake, its modes of trafficking within cells, to an overview of its downstream utilization in the cytoplasm and within mitochondria. The understanding of mitochondrial iron processing and its communication with other organelles/subcellular locations, such as the cytosol, has been elucidated by the analysis of certain diseases e.g., Friedreich's ataxia. Increased knowledge of the molecules and their mechanisms of action in iron processing pathways (e.g., ISC biogenesis) will shape the investigation of iron metabolism in human health and disease.

Vulnerability of Korean water resources to climate change and population growth

Freshwater availability is affected by changes in climate and growth. We assessed the freshwater vulnerability for five major Korean river basins for 2015 and 2030. We used a regional climate model based on the IPCC SRES A2 scenario, US Geological Survey's Precipitation Rainfall Simulation Model, and population and industrial growth scenarios for impact assessment. The model simulation results suggest increasing spatial and temporal variations of water stress for the basins that are already developed. While freshwater is more vulnerable to growth scenarios than the climate change scenario, climate change alone could decrease mean annual runoff by 10% in four major river basins by 2030. As the first national assessment of climate change, we suggest possible adaptive water resource management and policy strategies for reducing climate related risks in Korea.

Assessment of material degradation due to corrosion-fatigue using a backscattered Rayleigh surface wave

Material degradation due to corrosion-fatigue was evaluated nondestructively using backscattered Rayleigh surface wave. A corrosion-fatigue test was carried out for the specimens made of thermo-mechanically controlled process steel in 3.5 wt.% NaCl solution at 25 degrees C. The Backscattering profile, which is the amplitude variation of backscattered ultrasound according to the incident angle, of the specimens were measured in water at room temperature after the corrosion-fatigue test. The velocity of Rayleigh surface wave, determined from the incident angle at which the profile of the backscattered ultrasound became maximum, decreased for the specimen that had the large number of cycles to failure in the corrosion-fatigue test. This fact implies that the corrosion degradation occurred at specimen surface in this specific test is dominantly dependant on the time exposed to corrosion environment. The result observed in the present work demonstrates the high potential of backscattered Rayleigh surface wave as a tool for nondestructive evaluation of corrosion degradation of aged materials.

Mechanical properties and water-vapor permeability of soy-protein films affected by calcium salts and glucono-delta-lactone

Edible films were prepared from solutions of soy protein with calcium salts and glucono-delta-lactone (GDL). Calcium salts cross-linking interactions with soy-protein isolate (SPI) could result in the formation of films with rigid three-dimensional structure. GDL contributed to the formation of a homogeneous film structure due to increased protein--solvent attraction. Tensile strength (TS) of calcium sulfate treated SPI film (8.6 MPa) was higher than the TS of calcium chloride treated SPI films (6.4 MPa) and the control SPI film (5.5 MPa). Puncture strength (PS) of calcium sulfate treated SPI film (9.8 MPa) was higher than the PS of calcium chloride treated SPI films (8.5 MPa) and the control SPI film (5.9 MPa). SPI film formulated with GDL had larger elongation at break (39.4%) than that of SPI control film (18.2%). Calcium salts and GDL-treated SPI films had lower water-vapor permeability than the SPI control film.

Isothermal age-hardening behaviour in a Au-1.6 wt% Ti alloy

This study describes research with a view to developing a new age-hardenable, high-carat dental gold alloy with better biocompatibility by addition of a small quantity of titanium to gold. The relationship between isothermal age-hardening and phase transformation of the Au-1.6 wt% Ti alloy was investigated by means of hardness testing, X-ray diffraction study, scanning electron microscopic observation and energy dispersive spectroscopy. The hardening in the initial stage of ageing seemed to be attributable to the continuous precipitation of the Au4Ti ordered phase in the supersaturated alpha solid solution matrix. The overaging with softening was attributed mainly to the formation of precipitates at the grain boundaries, which grew to bright lamellae and seemed to be composed of the Au4Ti phase.

Comparison of classic intrafascial supracervical hysterectomy with total laparoscopic and laparoscopic-assisted vaginal hysterectomy

STUDY OBJECTIVE

To evaluate the efficacy of laparoscopic hysterectomy and compare classic intrafascial supracervical hysterectomy (CISH) with total laparoscopic hysterectomy (TLH) and laparoscopic-assisted vaginal hysterectomy (LAVH).

DESIGN

Retrospective review (Canadian Task Force classification II-2).

SETTING

University-affiliated hospital.

PATIENTS

Six hundred fifty women who underwent laparoscopic hysterectomy from August 1993 to August 1996.

INTERVENTIONS

Charts of 231 women undergoing CISH, 102 TLH, and 317 LAVH were reviewed regarding patient characteristics, indications, uterine weight, associated procedures, estimated blood loss, operating time, and complications.

MEASUREMENTS AND MAIN RESULTS

Among the three groups, despite having the largest specimen weight and highest number of associated procedures, women undergoing CISH had the lowest complication rate and smallest amount of estimated blood loss (p <0.05). The next lowest was the TLH group (p <0.05). Although LAVH was associated with shortest operating time, there were no statistically significant differences among groups (p >0.05). The CISH group had relatively shorter operating times when compared with similar average specimen weights. Patients who underwent total hysterectomy by either TLH or LAVH had more postoperative visits than those having CISH (p <0.05, Fisher's exact test); the LAVH group had the highest number of postoperative visits. The overall complication rate appeared to be highest in the LAVH group (p <0.05, Fisher's exact test).

CONCLUSION

Among the three groups, CISH resulted in lowest blood loss and fewest complications; these values were also lower for TLH than for LAVH. If the cervix is removed along with the uterus, TLH is recommended. In our opinion, CISH is preferred in cases of benign uterine diseases because it lowers major operative complications, especially in women who have large masses with no pathologic lesions of the cervix.

Mastication and rumination in relation to body size of cattle

Effect of body size on number of minutes per kilogram cell wall constituents spent chewing during eating and ruminating was studied in a total of 59 mature animals including 18 Holstein cows, 12 Jersey cows, 6 Ayrshire cows, 11 Guernsey cows, and 12 steers. Larger animals were more efficient chewers, spending less time chewing per kilogram of ingested cell wall constituents. Body size accounted for 52% and differences of intake of cell wall constituents accounted for an additional 22% of variability of chewing time. Neither breed nor ambient temperature contributed significantly to explaining the variability. Size of fecal particles and amount of each size did not differ significantly for different body sizes. These results suggest that acceptability of particles to the reticulo-omasal orifice was not different for different body sizes. Correlation was nil between body size and speed of chewing.

Efficiency of mastication in relation to hay intake by cattle

Four dry Holstein cows and four hay levels (50, 75, 100 and 125% of NRC-recommended dry matter intake) were used to study the efficiency of mastication and rumination in relation to hay intake. The experimental design was a 4 x 4 Latin square with 7-day periods. Increased hay levels resulted in increased rumination time, eating time, number of rechewings and boluses. When corrected for cell wall constituents (CWC) intake, rumination time decreased as level of hay intake increased, while eating time increased. Consequently, total chewing time per kilogram CWC intake did not differ (P less than .05) with hay level. Results indicate that ingested roughages required a constant amount of trituration either by eating or by rumination. The amount of each fecal particle size fraction retained by four different sieve sizes, and the total of these larger particles (above .3 mm), did not differ (P greater than .05) among hay levels. Results suggest that acceptability of indigestible particles by the reticulo-omasal orifice was not affected by the amount of hay intake.