Multivariate process trajectories for molecular description of MF thermal curing and correlation with hydrolytic stability

During curing of thermosetting resins the technologically relevant properties of binders and coatings develop. However, curing is difficult to monitor due to the multitude of chemical and physical processes taking place. Precise prediction of specific technological properties based on molecular properties is very difficult. In this study, the potential of principal component analysis (PCA) and principal component regression (PCR) in the analysis of Fourier transform infrared (FTIR) spectra is demonstrated using the example of melamine-formaldehyde (MF) resin curing in solid state. FTIR/PCA-based reaction trajectories are used to visualize the influence of temperature on isothermal cure. An FTIR/PCR model for predicting the hydrolysis resistance of cured MF resin from their spectral fingerprints is presented which illustrates the advantages of FTIR/PCR compared to the combination differential scanning calorimetry/isoconversional kinetic analysis. The presented methodology is transferable to the curing reactions of any thermosetting resin and can be applied to model other technologically relevant final properties as well.     

科帕卡格拉纳建筑 奥地利维亚纳

正科帕卡格拉纳位于新多瑙河12.5公里处,毗邻Reichsbrücke大桥。出于同旧有设计保持协调性考虑,力求能让大楼融入当地环境,迎合自身功能性需要,GERNER GERNER PLUS团队充分考虑现有周边环境,对大楼重新规划设计。新的设计突显建筑的特殊性和重要性,面向河流的立面是科帕卡格拉纳大楼最重要的部分,所以设计的重点也放在了这里。现有的城市中轴线是一个参照物,为了视觉上和氛围上形成一体化城市的感     

Fourier transform ion cyclotron resonance mass spectrometry at the true cyclotron frequency

Ion cyclotron resonance (ICR) cells provide stability and coherence of ion oscillations in crossed electric and magnetic fields over extended periods of time. Using the Fourier transform enables precise measurements of ion oscillation frequencies. These precisely measured frequencies are converted into highly accurate mass-to-charge ratios of the analyte ions by calibration procedures. In terms of resolution and mass accuracy, Fourier transform ICR mass spectrometry (FT-ICR MS) offers the highest performance of any MS technology. This is reflected in its wide range of applications. However, in the most challenging MS application, for example, imaging, enhancements in the mass accuracy of fluctuating ion fluxes are required to continue advancing the field. One approach is to shift the ion signal power into the peak corresponding to the true cyclotron frequency instead of the reduced cyclotron frequency peak. The benefits of measuring the true cyclotron frequency include increased tolerance to electric fields within the ICR cell, which enhances frequency measurement precision. As a result, many attempts to implement this mode of FT-ICR MS operation have occurred. Examples of true cyclotron frequency measurements include detection of magnetron inter-harmonics of the reduced cyclotron frequency (i.e., the sidebands), trapping field-free (i.e., screened) ICR cells, and hyperbolic ICR cells with quadrupolar ion detection. More recently, ICR cells with spatially distributed ion clouds have demonstrated attractive performance characteristics for true cyclotron frequency ion detection. Here, we review the corresponding developments in FT-ICR MS over the past 40 years.     

Effect of laboratory foamer on asphalt foaming characteristics and foamed mixture properties

In the United States, mechanical foaming is the most popular method for producing warm mix asphalt, which is the latest technology implemented to reduce the production temperature and/or enhance the compactability of asphalt mixtures. Three commonly used commercially available laboratory foamers to produce asphalt foams include the Wirtgen WLB 10S (Wirtgen foamer), the InstroTek Accufoamer (InstroTek foamer) and the Pavement Technology Inc. Foamer (PTI foamer). Though these foamers have been widely used in research studies and construction practice, it is still unknown whether they produce asphalt foams with the same quality and quantity. In this study, asphalt foaming characteristics produced by these three laboratory foamers were measured using a non-contact test set-up consisting of a laser device and a digital camera, and compared in terms of instantaneous volume expansion, foam stability and surface area evolution of foam bubbles. Additionally, the workability, coatability and mechanical performance of foamed mixtures prepared using these same laboratory foamers were compared against the conventional hot mix asphalt (HMA). Test results indicated that foamed asphalts produced by the Wirtgen foamer had the largest volume expansion and greatest foam stability, followed by those produced by the InstroTek foamer and the PTI foamer. The optimum foaming water content (W_opt) was determined for each laboratory foamer based on the workability and coatability results of the corresponding foamed mixtures. In addition, the performance evaluation of the foamed mixtures produced at W_opt values indicated equivalent mixture stiffness but greater moisture susceptibility as compared to the conventional HMA.     

Implicit measures of early-life family conditions: Relationships to psychosocial characteristics and cardiovascular disease risk in adulthood.

Objectives: An implicit measure of early-life family conditions was created to help address potential biases in responses to self-reported questionnaires of early-life family environments. We investigated whether a computerized affect attribution paradigm designed to capture implicit, affective responses (anger, fear, warmth) regarding early-life family environments was (a) stable over time, (b) associated with self-reports of childhood family environments, (c) able to predict adult psychosocial profiles (perceived social support, heightened vigilance), and (d) able to predict adult cardiovascular risk (blood pressure) either alone or in conjunction with a measure of early-life socioeconomic status. Method: Two studies were conducted to examine reliability and validity of the affect attribution paradigm (Study 1, N = 94) and associated adult psychosocial outcomes and cardiovascular risk (Study 2, N = 122). Results: Responses on the affect attribution paradigm showed significant correlations over a 6-month period, and were moderately associated with self-reports of childhood family environments. Greater attributed negative affect about early-life family conditions predicted lower levels of current perceived social support and heightened vigilance in adulthood. Attributed negative affect also interacted with early-life socioeconomic status (SES) to marginally predict resting systolic blood pressure (SBP), such that those individuals high in early-life SES but who had implicit negative affect attributed to early-life family conditions had SBP levels that were as high as individuals low in early-life SES. Conclusion: Implicit measures of early-life family conditions are a useful approach for assessing the psychosocial nature of early-life environments and linking them to adult psychosocial and physiological health profiles. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Zoning and the Nouveau Poor

The nouveau poor, women heading households, who have experienced a dramatic shift from middle income to low income status due to divorce, widowhood, or abandonment, and who own their own homes in America's suburban and small towns constitute a demographic group whose housing opportunities are limited by certain restrictive zoning practices.

Outmoded regulations, such as those with restrictive definitions of family and age-restrictive zoning regulations and covenants, deny these families the opportunity to enter into housesharing arrangements or to divide their homes into principal and accessory units. Because of these policies, nouveau poor families may find that they cannot continue to live in the communities that they had sought out as ideal places for raising their children. Although restrictive zoning regulations have generally been upheld by the courts, they have at times been successfully attacked. An understanding of the court decisions and their public policy implications will provide guidance for land use officials so they can respond to the housing needs of the nouveau poor.     

Improvement of emulsifying properties of milk proteins with κ or λ carrageenan: effect of pH and ionic strength

The objective of this work was to determine the effect of λ‐carrageenan or κ‐carrageenan on the emulsion capacity, emulsion work and emulsion stability of milk proteins concentrate (MP) or sodium caseinate (SC) emulsions at different levels of pH and ionic strength. Incorporation of carrageenans to proteins emulsions resulted in an improvement of emulsifying properties at pH 6.0 and low ionic strength (0.2 m NaCl). Although emulsion capacity was high in MP than for SC, irrespectively of carrageenan employed, addition of λ‐carrageenan increased twofold emulsion work values (15 327 Ω s^?1 for MP and 11 455 Ω s^?1 for SC; around 6000 Ω s^?1 in the other treatments). Emulsion stability was high with λ‐carrageenan (9.8 s) than MP‐κ‐carrageenan or MP (7.45 and 7.40 s, respectively). Carrageenan improving of emulsion properties was because of the complex formation with MP, characteristic of this type of food system when pH was above of isoelectric point.     

Numerical analysis of moisture vapor diffusion in asphalt mixtures using digital images

The presence of moisture in asphalt mixtures is detrimental to their performance, e.g., softening the asphalt binder and weakening the aggregate-binder bond. One of the mechanisms of moisture transport, and the focus of this study, is molecular diffusion. Moisture diffusion occurs in response to a concentration gradient. The objective of this study was to estimate the diffusion coefficient of moisture vapor in asphalt mixtures by using finite element (FE) and finite difference (FD) numerical algorithms that employ digital images to discretize the composite. X-ray computed tomography was used to characterize the microstructure of laboratory-prepared specimens and provide the required three-dimensional digital images, which were segmented into three phases: air voids, a mixture of asphalt binder and the fine aggregate fraction, and coarse aggregates. Individual diffusion coefficients were assigned to each phase and the effective diffusion coefficient for the composite was computed using the numerical algorithms. The outcome was compared against experimental values. The effective diffusion coefficient for the asphalt mixtures obtained using the FD method showed closer agreement with the experimental data, while the FE results overestimated the experimental measurements in all cases.