Origin of Spurious Ultrasonic Echoes in Stainless Steel Piping with Weld Overlay

The initiation and growth of intergranular stress-corrosion cracking (IGSCC) in the heat-affected zone of welds in stainless steel reactor piping has been a subject of concern to electric utilities for over ten years. This type of crack can be detected with ultrasonic shear waves during normal maintenance periods with a reliability of up to 80% [1]. Often, when crack indications have been found, the utility has been allowed to apply a weld metal overlay as a temporary repair measure. However, the complex, elastically anisotropic microstructure of the overlay considerably reduces the reliability of subsequent ultrasonic inspections. This paper addresses the problems arising because of the overlay

Shelf life and microbial content of fluid milk from nine processing plants in Oregon

High-temperature-short-time pasteurized fluid milk commonly has a shelf life around 16-19 days. The aim of this study was to determine the shelf life of fluid milk in Oregon and characterize the bacterial growth over 23 days. Samples of pasteurized 2% milk were collected at six time points from all nine fluid milk-processing plants within Oregon. Milk was collected at 23, 21, 19, 16, and 8 days pre-testing, allowing for aging to occur. Fresh samples were collected 24 hours pre-testing. Raw milk samples were collected twice at 23 days and within 24 hours of testing for enumeration of endospores. Samples from each time point were cultured for Total Plate Count (TPC), and gram-negative counts (GNC). Concurrently, shelf lives of the milk were determined by employing triangle tests (N=25) where milk-drinking consumers were asked to distinguish between fresh and aged milk samples. Shelf lives varied greatly among the nine processing plants ranging from less than 8 to 21 days. Two accelerated milk shelf-life tests, the Pre-Incubation Count (PI) and the Moseley Keeping Quality (MKQ) test were also conducted. Both accelerated shelf life tests failed to accurately predict the shelf lives among plants. TPC's at 23 days of age were within one log value of 10⁶cfu/ml among all nine dairy plants. Endospore counts (ESC) ranged from 10³-10⁷ at 23 days. ESC counts trailed the TPC and gram-negative counts, as high numbers of spores were not seen until after 16 days. GNC counts followed the TPC closely. The four dairies with the shortest shelf lives utilized coated paperboard carton packaging. Microbial content and packaging material showed no correlation. Pasteurization temperature did not correlate to the bacterial growth, although the five plants with the shortest shelf lives utilized the longest holding times. Bacterial species in raw and pasteurized milk samples were identified using Terminal Restriction Fragment Length Polymorphism (t-RFLP). Paenibacillus spp. were the most commonly found organism in the pasteurized samples. Pseudomonas spp. were only found in one pasteurized sample, however they were found in 56% of the raw milk samples. Streptococcus spp. were found in the pasteurized milk of the four plants with the shortest shelf lives and are a possible cause of reduced shelf life. This study demonstrates that although pasteurized milk processing is a well-established process, there is still significant variability in the milk quality and shelf life between dairy plants

Analytic Diffraction Corrections to Ultrasonic Scattering Measurements

Ultrasonic theories generally predict a scattering amplitude which relates a spherically spreading, far-field scattered wave to an incident plane wave. In ultrasonic immersion measurements, the frequency and angular dependences of the scattering amplitude are convolved with those of the transmitting and receiving transducers and the propagation through the liquid-solid and solid-liquid interfaces. This paper presents a set of approximate corrections for these effects for the cases of angle beam inspection through planar, spherically curved or cylindrically curved surfaces. The primary parameters in the correction are the function D, which corrects for the diffraction effects occurring during a transducer calibration experiment, and the function C, which describes the on-axis pressure variation of the beam. Values of C and D are available in the literature for the case of a piston transducer radiating into an infinite fluid medium. The major portion of this paper is concerned with the extension of those results to the aforementioned two media problems in which mode conversion, refraction, diffraction, and focussing all play interrelated roles. Results of preliminary experiments to test the corrections are also included

Chloroquine activates the p53 pathway and induces apoptosis in human glioma cells

Glioblastoma is the most common malignant brain tumor in adults. The currently available treatments offer only a palliative survival advantage and the need for effective treatments remains an urgent priority. Activation of the p53 growth suppression/apoptotic pathway is one of the promising strategies in targeting glioma cells. We show that the quinoline derivative chloroquine activates the p53 pathway and suppresses growth of glioma cells in vitro and in vivo in an orthotopic (U87MG) human glioblastoma mouse model. Induction of apoptosis is one of the mechanisms underlying the effects of chloroquine on suppressing glioma cell growth and viability. siRNA-mediated downregulation of p53 in wild-type but not mutant p53 glioblastoma cells substantially impaired chloroquine-induced apoptosis. In addition to its p53-activating effects, chloroquine may also inhibit glioma cell growth via p53-independent mechanisms. Our results clarify the mechanistic basis underlying the antineoplastic effect of chloroquine and reveal its therapeutic potential as an adjunct to glioma chemotherapy