Transgranular liquation cracking of grains in the semi-solid state.

Grain refinement via semi-solid deformation is desired to obtain superior mechanical properties of cast components. Using quantitative in situ synchrotron X-ray tomographic microscopy, we show an additional mechanism for the reduction of grain size, via liquation assisted transgranular cracking of semi-solid globular microstructures. Here we perform localized indentation of Al-15wt.%Cu globular microstructures, with an average grain size of ∼480 µm, at 555 °C (74% solid fraction). Although transgranular fracture has been observed in brittle materials, our results show transgranular fracture can also occur in metallic alloys in semi-solid state. This transgranular liquation cracking (TLC) occurs at very low contact stresses (between 1.1 and 38 MPa). With increasing strain, TLC continues to refine the size of the microstructure until the grain distribution reaches log-normal packing. The results demonstrate that this refinement, previously attributed to fragmentation of secondary arms by melt-shearing, is also controlled by an additional TLC mechanism.

Pulmonary staging in colorectal cancer: a review.

AIM: Assessment of the chest in colorectal cancer (CRC) staging is variable. The aim of this review was to look at different chest staging strategies and determine which has the greatest efficacy. METHOD: A review of studies assessing chest staging modalities for patients with CRC was performed. Modalities included chest X-ray (CXR), CT and positron emission tomography (PET). RESULTS: The majority of data consisted of case series. Two studies identified a low pick-up rate for CXR as a staging tool. Five studies showed increased detection rates of pulmonary metastases for chest CT vs CXR and abdominal CT. The clinical benefit of the increased detection rates was not clear. The incidence of indeterminate lung lesions (ILL) on staging chest CT varied from 4 to 42%. The majority (≥ 70%) of ILLs did not have any clinical significance. On CT scans, the incidence of pulmonary metastases in patients with rectal cancer ranged from 10 to 18% and in patients with colon cancer the incidence of pulmonary metastases ranged from 5-6%. The incidence of synchronous liver and pulmonary metastases compared with the overall incidence of pulmonary metastases ranged from 45 to 70%. There was no evidence reporting the superiority of PET/CT vs CT for the detection of pulmonary metastases or characterization of ILL. CONCLUSION: Studies show that chest CT scanning increases the detection rates for ILL and pulmonary metastases. The clinical benefit of the increased detection rates is not clear. There is a paucity of data assessing the optimal chest staging strategy for patients presenting with CRC.

Folic acid supplementation and colorectal cancer risk: a meta-analysis.

AIM: This meta-analysis aims to determine the effect of folic acid supplementation on colorectal cancer risk. METHOD: A structured search of the MEDLINE, EMBASE, Cochrane and CINAHL databases was undertaken in July 2008. All published full text English language articles were searched that included a randomized or pseudo-randomized comparison of subjects who received folate vs subjects who did not in relation to their risk of adenoma or advanced adenomatous lesions, including colorectal cancer. A weighted treatment effect (using fixed effects) was calculated across trials. RESULTS: Overall, the risk of an adenomatous lesion was not increased (odds ratio 1.09, 95% confidence interval 0.93-1.28) among patients who received folate supplementation for up to 3 years; however, for those who received folate for over 3 years, the risk of an adenomatous lesion was increased (odds ratio 1.35, 95% confidence interval 1.06-1.70). The risk associated with treatment was the highest for the occurrence of an advanced lesion (odds ratio 1.50, 95% confidence interval 1.06-2.10). There was no significant statistical heterogeneity in the analyses. CONCLUSION: At the 3-year colonoscopic follow up, folate supplementation had no effect on adenoma recurrence overall. While colonic surveillance beyond 3 years revealed an increased risk of colorectal adenoma, especially advanced adenoma, among those participants randomized to the folate group. This meta-analysis challenges the results from epidemiological studies that folate status is inversely related to the risk of developing colorectal cancer.

The power output of laser pointers: do they exceed federal standards?

BACKGROUND: Concern about the safety of laser pointers has increased as these devices have become readily available to the public, which includes children who may use them improperly. According to federal (Food and Drug Administration) standards, laser pointers are class 3a devices, and power output cannot exceed 5.0 mW. METHODS: We tested a sample consisting of 29 red diode laser pointers obtained from various sources that were equipped with fresh batteries. Power output was measured with an optical power meter with the sensor 5.0 cm from the laser. The laser was turned on for 60 s and a reading was taken every 10 s. This procedure was repeated five times for every laser. RESULTS: The power output of unaltered lasers ranged from 0.7 mW to a high of 3.9 mW. Alterations to some of the lasers increased the output slightly above 5.0 mW. CONCLUSIONS: When the laser pointers in our sample were used as packaged, they did not exceed the federal standards of 5.0 mW.

Effect of Liquid Nutrient Culture, Vacuum Distillation and Dialysis on Hatching Activity of Sugar Beet Root Diffusate for Heterodera schachtii.

Roots of sugar beets grown in liquid culture excrete substances that stimulate egg hatch and emergence of larvae from cysts of Heterodera schachtii. Their hatching effect is comparable to that of sugar beet root diffusate leached from soil-grown sugar beet plants. Consequently, liquid culture provides a way of obtaining H. schachtii hatch-stimulant free of contaminants from soil. Root diffusate, concentrated 50-fold or dried by vacuum distillation, retained hatching activity. The active principle of diffusate is dialyzable with a diffusion rate between those of inorganic salts and compounds with molecular weights greater than 15,000.