Temporal Nature of Fatigue Damage in Highway Bridges

To develop a valid method of estimating fatigue life of a highway bridge, it is first necessary to have a reasonable understanding of the manner in which fatigue damage occurs over time. This paper presents the findings from an extensive highway bridge monitoring program focused on monitoring vehicle-induced strain cycles; the cause of fatigue damage. The purpose of the study was to identify the temporal character (if any) of fatigue damage accumulation. A sample of 24 bridges in the State of Ohio was monitored; each bridge in the sample for 1?year. The data collected during the study captured hourly, daily, and monthly variation in fatigue damage accumulation. The raw data were resolved to a fatigue damage metric representation. The damage metric was analyzed with the intent of determining the temporal nature of fatigue damage accumulation. The analyses led to the development of postulates regarding fatigue damage in highway bridges. The postulates stated in this study should provide a sound basis for development of a fatigue-life estimation procedure using site-specific strain cycle histograms collected over an abbreviated time window.     

Short communication: Effect of pH on the heat stability of reconstituted reduced calcium milk protein concentrate dispersions

This study aimed to investigate the heat stability of dispersions from reconstituted reduced-calcium milk protein concentrate (RCMPC) with 80% protein or more. The tested RCMPC powders were produced from skim milk subjected to CO₂ treatment before and during the process of ultrafiltration. The CO₂ injection was controlled to obtain 0 (control, no CO₂ injection), 20, 30, and 40% reduction in calcium levels in the RCMPC powders. The RCMPC powders were reconstituted to 10% (wt/wt) protein in deionized water. These dispersions were tested for heat stability in a rocking oil bath at 140°C at unadjusted, 6.5, 6.7, 6.9, and 7.1 pH. Calcium ion activity (CIA) and ionic strength measurements were carried out using a Ca ion-selective electrode and conductivity meter. Unadjusted pH of the dispersions varied from 6.8 in control to 5.96 in 40% RCMPC dispersions. The CIA of unadjusted dispersions ranged from 1.31 mM in control to 2.83 mM in 40% RCMPC. Heat stability, expressed as heat coagulation time (HCT) of unadjusted dispersions decreased as the level of Ca removal in powders increased (from 13.81 min in control to 0.46 min in 40% RCMPC) and was negatively correlated with the CIA of the dispersions. For control RCMPC dispersions, the minimum and maximum heat stability were observed at dispersion pH of 6.5 and 6.9, respectively, followed by a decrease at pH 7.1 (CIA was the lowest). Dispersions from 40% RCMPC and pH 7.1 had the maximum HCT of 30.94 min among all RCMPC dispersions at all pH values. From this study, it can be concluded that improved heat stability in high protein formulation beverages subjected to UHT processing could be achieved through calcium reduction in milk protein concentrates using CO₂ injection.     

Small-scale manufacture of process cheese using a rapid visco analyzer

Numerous formulation and processing parameters influence the functional properties of process cheese. Recently, a small-scale (25 g) manufacturing and analysis method was developed using a rapid visco analyzer (RVA), which was designed to evaluate the functional properties of process cheese when subjected to various formulations and processing conditions. Although this method successfully manufactured process cheese, there was a significant difference in the functional properties of the process cheese compared with process cheese manufactured on a pilot scale. In the present study, adjustments in the RVA methodology involving the RVA processing conditions, preblend preparation, and texture profile analysis (TPA) techniques for the final process cheese were investigated. Fourteen samples of pasteurized processed cheese food (PCF) were manufactured from 14 different preblends. Each pre-blend was prepared using 1 of the 14 different natural cheeses and was balanced for moisture, fat, and salt. Each of these 14 preblends was split into 3 portions and each portion was subjected to 3 different manufacturing treatments. The first treatment was manufactured in a pilot-scale Blentech twin screw (BTS) cooker, and the remaining 2 treatments were manufactured in an RVA with different processing profiles. The RVA treatments were produced in triplicate. The resulting process cheeses were analyzed for moisture and functional properties. Texture profile analysis and RVA melt analyses were performed on all PCF treatments. Additionally, for the RVA treatments, the data for time of emulsification and end apparent viscosity during RVA manufacture were collected and recorded. The functional properties of the PCF manufactured using the RVA treatments showed good correlation with the functional properties of the PCF produced on the pilot scale. Additionally, the end apparent viscosity during RVA manufacture was correlated with the functional properties of the process cheese. Consequently, the RVA can be used as a small-scale manufacturing and analysis tool for predicting the functional properties of process cheese, and for evaluating how various formulations and processing parameters affect these functional properties. Moreover, the adjustments in the RVA methodology produced process cheese with functionality similar to process cheese produced in the BTS.     

Real-time measurement of oligomeric species in secondary organic aerosol with the aerosol time-of-flight mass spectrometer

Real-time detection of oligomers in secondary organic aerosols has been carried out with an aerosol time-of-flight mass spectrometer sampling particles generated in a smog chamber. The photooxidation products of 1,3,5-trimethylbenzene and NOx were studied over a range of initial 1,3,5-trimethylbenzene concentrations (137-1180 ppb), while keeping the 1,3,5-trimethylbenzene to NOx ratio nearly constant. The photooxidation products of a mixture of alpha-pinene (initial concentration 191 ppb), 1,3,5-trimethylbenzene (60 ppb), and NOx were also investigated. In both systems, ions were observed in the single-particle mass spectra up to 750 Da; the species observed differed in the two systems. These high-mass ions occur with characteristic spacing of 14 and 16 Da, indicative of oligomeric species. The results obtained agree well with off-line (matrix-assisted) laser desorption/ionization mass spectrometry results. The real-time capabilities of the aerosol time-of-flight mass spectrometer make it possible to investigate the temporal development of the oligomers with 5-min time resolution and also demonstrate that there are certain ions within the oligomer population that occur in nearly all of the particles and with relatively high signal intensity, suggesting that these ions have higher stability or that the species are formed preferentially.     

Comparative Optimism About Privacy Risks on Facebook

Comparatively optimistic people feel that they are less susceptible to risks than are others. This study investigated predictors and outcomes of comparative optimism about privacy risks on Facebook. Results from a nationally representative survey of adult U.S. Facebook users (N = 1,156) show that users exhibit comparative optimism in believing that they are less susceptible to privacy risks than are average users. However, unlike prior findings in offline contexts, this study finds that comparatively optimistic Facebook users do not appear to engage in riskier privacy behaviors. The findings of this study shed light on how privacy decision-making may be different in social networking contexts compared to other contexts due to the networked nature of the communication platform.     

Development of a sensitive E-screen assay for quantitative analysis of estrogenic activity in municipal sewage plant effluents

A simplified proliferation test with human estrogen receptor-positive MCF-7 breast cancer cells (E-screen assay) was optimized and validated for the sensitive quantitative determination of total estrogenic activity in effluent samples from municipal sewage plants. After solid phase extraction of 1 l sewage on either 0.2 g polystyrene copolymer (ENV+) or 1 g RP-C18 material and removal of the solvent, analysis of the extracts in the E-screen assay could be performed without any clean-up step. This was even possible with untreated sewage. Parallel extraction of four sewage samples on both different solid phase materials gave comparable quantitative results in the E-screen. A blank sample did not induce cell proliferation. As additive behaviour of the estrogenic response of single compounds was proven for two different mixtures each containing three xenoestrogens, total estrogenic activity in the sewage samples, expressed as 17 beta-estradiol equivalent concentration (EEQ), could be calculated comparing the EC50 values of the samples with those of the positive control 17 beta-estradiol. The detection limit of the E-screen method was 0.05 pmol EEQ/l (0.014 ng EEQ/l), the limit of quantification 0.25-0.5 pmol EEQ/l (0.07-0.14 ng EEQ/l). In total, extracts of nine effluent and one influent sample from five different municipal sewage plants in South Germany were analyzed in the E-screen. All samples strongly induced cell proliferation in a dose-dependent manner which was completely inhibited by coincubation with 5 nM of the estrogen receptor-antagonist ICI 182,780. The proliferative effect relative to the positive control 17 beta-estradiol (RPE) was between 30 and 101%. 17 beta-Estradiol equivalent concentrations were between 2.5 and 25 ng/l indicating a significant input of estrogenic substances via sewage treatment plants into rivers.     

Influence of milk protein concentrates with modified calcium content on enteral dairy beverage formulations: Physicochemical properties

Because of their high protein and low lactose content, milk protein concentrates (MPC) are typically used in the formulation of ready-to-drink beverages. Calcium-mediated aggregation of proteins during storage is one of the main reasons for loss of storage stability of these beverages. Control and calcium-reduced MPC [20% calcium-reduced (MPC-20) and 30% calcium-reduced (MPC-30)] were used to evaluate the physicochemical properties in this study. This study was conducted in 2 phases. In phase I, 8% protein solutions were prepared by reconstituting the 3 MPC and adjusting the pH to 7. These solutions were divided into 3 equal parts, 0, 0.15, or 0.25% sodium hexametaphosphate (SHMP) was added, and the solutions were homogenized. In phase II, enteral dairy beverage formulations containing MPC and a mixture of gums, maltodextrin, and sugar were evaluated following the same procedure used in phase I. In both phases, heat stability, apparent viscosity, and particle size were compared before and after heat treatment at 140°C for 15 s. In the absence of SHMP, MPC-20 and MPC-30 exhibited the highest heat coagulation time at 30.9 and 32.8 min, respectively, compared with the control (20.9 min). In phase II, without any addition of SHMP, MPC-20 exhibited the highest heat coagulation time of 9.3 min compared with 7.1 min for control and 6.2 min for MPC-30. An increase in apparent viscosity and a decrease in particle size of reconstituted MPC solutions in phases I and II with an increase in SHMP concentration was attributed to casein micelle dissociation caused by calcium chelation. This study highlights the potential for application of calcium-reduced MPC in dairy-based ready-to-drink and enteral nutrition beverage formulations to improve their heat stability.     

Influence of calcium and phosphorus, lactose, and salt-to-moisture ratio on Cheddar cheese quality: manufacture and composition

Eight Cheddar cheeses with 2 levels of calcium (Ca) and phosphorus (P), residual lactose, and salt-to-moisture ratio (S/M) were manufactured. All cheeses were made using a stirred-curd procedure and were replicated 3 times. Treatments with a high level of Ca and P were produced by setting the milk and drawing the whey at a higher pH (6.6 and 6.3, respectively) compared with the treatments with a low level of Ca and P (pH of 6.2 and 5.7, respectively). The lactose content in the cheeses was varied by adding lactose (2.5% by weight of milk) to the milk for high lactose cheeses, and washing the curd for low lactose cheeses. The difference in S/M was obtained by dividing the curds into halves, weighing each half, and salting at 3.5 and 2.25% of the weight of the curd for high and low S/M, respectively. All cheeses were salted at a pH of 5.4. Modifications in cheese-making protocols produced cheeses with desired differences in Ca and P, residual lactose, and S/M. Average Ca and P in the high Ca and P cheeses was 0.68 and 0.48%, respectively, vs. 0.53 and 0.41% for the low Ca and P cheeses. Average lactose content of the high lactose treatments at d 1 was 1.48% compared with 0.30% for the low lactose treatments. The S/M for the high and low S/M cheeses was 6.68 and 4.77%, respectively. Mean moisture, fat, and protein content of the cheeses ranged from 32.07 to 37.57%, 33.32 to 35.93%, and 24.46 to 26.40%, respectively. The moisture content differed among the treatments, whereas fat and protein content on dry basis was similar.