Quantification of sulfur distribution on rubber surfaces by means of μ-X-ray fluorescence analysis

A homogeneous distribution of sulfur in a rubber compound is often desired. Spatially resolved imaging techniques are useful for evaluating the distribution of this crosslinking chemical. Typical measurement methods such as SEM (scanning electron microscopy) or TEM (transmission electron microscopy) have very high resolutions. However, the sample size or the maximum area to be investigated is limited, which makes it difficult to obtain a statistically reliable determination of sulfur homogeneity across the component or sample. In this work, an alternative measurement technique is therefore presented: the μ-XRF (μ-X-ray fluorescence analysis). With the help of this method, it is possible to scan surfaces of several cm2 and to show the distribution of different chemical elements. Its measuring principle has been known for decades but has hardly been used in the rubber industry so far. The main reason for this is that its quantification process for polymeric samples is more complex than for geologic or metallic samples, which are typically been investigated with μ-XRF to date. In this paper, this issue is addressed and a solution is presented: With the help of the fundamental parameter method, the determination of sulfur homogeneity and distribution on rubber surfaces becomes possible. This opens up a variety of further possibilities for the use of μ-XRF in the rubber industry: For example, it could be used in areas of tire production, recycling of end-of-life rubber, and beyond.</p

Colocalization of neurons in optical coherence microscopy and Nissl-stained histology in Brodmann’s area 32 and area 21

Published in final edited form as: Brain Struct Funct. 2019 January ; 224(1): 351–362. doi:10.1007/s00429-018-1777-z.Optical coherence tomography is an optical technique that uses backscattered light to highlight intrinsic structure, and when applied to brain tissue, it can resolve cortical layers and fiber bundles. Optical coherence microscopy (OCM) is higher resolution (i.e., 1.25 µm) and is capable of detecting neurons. In a previous report, we compared the correspondence of OCM acquired imaging of neurons with traditional Nissl stained histology in entorhinal cortex layer II. In the current method-oriented study, we aimed to determine the colocalization success rate between OCM and Nissl in other brain cortical areas with different laminar arrangements and cell packing density. We focused on two additional cortical areas: medial prefrontal, pre-genual Brodmann area (BA) 32 and lateral temporal BA 21. We present the data as colocalization matrices and as quantitative percentages. The overall average colocalization in OCM compared to Nissl was 67% for BA 32 (47% for Nissl colocalization) and 60% for BA 21 (52% for Nissl colocalization), but with a large variability across cases and layers. One source of variability and confounds could be ascribed to an obscuring effect from large and dense intracortical fiber bundles. Other technical challenges, including obstacles inherent to human brain tissue, are discussed. Despite limitations, OCM is a promising semi-high throughput tool for demonstrating detail at the neuronal level, and, with further development, has distinct potential for the automatic acquisition of large databases as are required for the human brain.Accepted manuscrip

Candidate screening for the recruitment of critical research and development workers - a report and preliminary results with evidence from experimental data from German high-tech firms

The report focuses on résumé-based screening strategies for the recruitment of highly qualified research and development (R&D) workers (critical R&D workers) in high-tech firms. We investigate which kinds of professional background, job-related experience, motivations, specific skills, and previous inventive activity make a candidate attractive for firms specializing in clean technology or mechanical elements. The report is based on a combination of survey and experimental data collected from 194 HR decision makers in German high-tech firms and from 89 technology experts in the clean technology and mechanical elements fields. A mixed logit model is used to analyse hiring preferences because this model allows us to deal with repeated choices. We find that HR decision makers prefer candidates with technology-specific patenting experience, an engineering background, analytical thinking skills, and a strong desire to develop path-breaking technologies. Furthermore, no one-size-fits-all candidate exists that is equally preferred in both technology fields. HR decision makers in mechanical element firms prefer specialists to generalists, whereas those in clean technology attach special importance to a candidate’s orientation towards environmental concerns and sustainability

Multispectral Imaging for Determination of Astaxanthin Concentration in Salmonids

Multispectral imaging has been evaluated for characterization of the concentration of a specific cartenoid pigment; astaxanthin. 59 fillets of rainbow trout, Oncorhynchus mykiss, were filleted and imaged using a rapid multispectral imaging device for quantitative analysis. The multispectral imaging device captures reflection properties in 19 distinct wavelength bands, prior to determination of the true concentration of astaxanthin. The samples ranged from 0.20 to 4.34 g per g fish. A PLSR model was calibrated to predict astaxanthin concentration from novel images, and showed good results with a RMSEP of 0.27. For comparison a similar model were built for normal color images, which yielded a RMSEP of 0.45. The acquisition speed of the multispectral imaging system and the accuracy of the PLSR model obtained suggest this method as a promising technique for rapid in-line estimation of astaxanthin concentration in rainbow trout fillets

Concrete Box Beam Risk Assessment and Mitigation: Volume 2—Evaluation and Structural Behavior

Adjacent box beam bridges have a history of poor long-term performance including premature deterioration and failures. Leaking joints between box beams allow chloride-laden water to migrate through the superstructure and initiate corrosion. The nature of this deterioration leads to uncertainty of the extent and effect of deterioration on structural behavior. Due to limitations in previous research and understanding of the strength of deteriorated box beam bridges, conservative assumptions are made for the assessment and load rating of these bridges. Furthermore, the design of new box beam bridges, which can offer an efficient and economical solution, is often discouraged due to poor past performance. The objective of this research is to develop recommendations for inspection, load-rating, and design of adjacent box beam bridges. The research is presented in two volumes. Volume 1 focuses on the evolution of box beam design in Indiana to understand the lack of performance and durability. The Indiana Department of Transportation (INDOT) standards and bridge design manuals were reviewed to track the historical development of box beam bridges in the State. Two timelines were produced tracking important updates to box beam design. Adjacent box beam bridges within INDOT’s bridge database were also analyzed. Superstructure ratings were compared with bridge age as well as bridge characteristics to highlight possible causes for deterioration. Analyzing the INDOT inventory, data shows that the condition of adjacent box beam bridges may be affected by location, type of wearing surface, and the use of deck membranes. Six bridges were then inspected to identify common deficiencies and specific problems. Exterior beams and beams within the wheel load path tend to have higher levels of deterioration. Furthermore, leaking joints between beams leads to corrosion of reinforcement, ultimately resulting in spalling, fracture of prestressing strands, and loss of structural capacity. Volume 2 focuses on evaluating the capacity of deteriorated adjacent box beams, the development of improved load rating procedures, and new box beam design. Through a series of bridge inspections, deteriorated box beams were identified and acquired for experimental testing. The extent of corrosion was determined through visual inspection, non-destructive evaluation, and destructive evaluation. Non-destructive tests (NDT) included the use of connectionless electrical pulse response analysis (CEPRA), ground penetrating radar (GPR), and half-cell potentials. Deteriorated capacity was determined through structural testing, and an analysis procedure was developed to estimate deteriorated behavior. A rehabilitation procedure was also developed to restore load transfer of adjacent beams in cases where shear key failures are suspected. Based on the understanding of deterioration developed through study of deteriorated adjacent box beam bridges, improved inspection and load rating procedures are provided along with design recommendations for the next generation of box beam bridges

Repair and Strengthening of Bridges in Indiana Using Fiber Reinforced Polymer Systems: Volume 1–Review of Current FRP Repair Systems and Application Methodologies

For bridges that are experiencing deterioration, action is needed to ensure the structural performance is adequate for the demands imposed. Innovate repair and strengthening techniques can provide a cost-effective means to extend the service lives of bridges efficiently and safely. The use of fiber reinforced polymer (FRP) systems for the repair and strengthening of concrete bridges is increasing in popularity. Recognizing the potential benefits of the widespread use of FRP, a research project was initiated to determine the most appropriate applications of FRP in Indiana and provide recommendations for the use of FRP in the state for the repair and strengthening of bridges. The details of the research are presented in two volumes. Volume 1 provides the details of a study conducted to (1) summarize the state-of-the-art methods for the application of FRP to concrete bridges, (2) identify successful examples of FRP implementation for concrete bridges in the literature and examine past applications of FRP in Indiana through case studies, and (3) better understand FRP usage and installation procedures in the Midwest and Indiana through industry surveys. Volume 2 presents two experimental programs that were conducted to develop and evaluate various repair and strengthening methodologies used to restore the performance of deteriorated concrete bridge beams. The first program investigated FRP flexural strengthening methods, with a focus on adjacent box beam bridges. The second experimental program examined potential techniques for repairing deteriorated end regions of prestressed concrete bridge girders. Externally bonded FRP and near-surface-mounted (NSM) FRP were considered in both programs

Concrete Box Beam Risk Assessment and Mitigation: Volume 1—Evolution and Performance

Adjacent box beam bridges have a history of poor long-term performance including premature deterioration and failures. Leaking joints between box beams allow chloride-laden water to migrate through the superstructure and initiate corrosion. The nature of this deterioration leads to uncertainty of the extent and effect of deterioration on structural behavior. Due to limitations in previous research and understanding of the strength of deteriorated box beam bridges, conservative assumptions are made for the assessment and load rating of these bridges. Furthermore, the design of new box beam bridges, which can offer an efficient and economical solution, is often discouraged due to poor past performance. The objective of this research is to develop recommendations for inspection, load-rating, and design of adjacent box beam bridges. The research is presented in two volumes. Volume 1 focuses on the evolution of box beam design in Indiana to understand the lack of performance and durability. The Indiana Department of Transportation (INDOT) standards and bridge design manuals were reviewed to track the historical development of box beam bridges in the State. Two timelines were produced tracking important updates to box beam design. Adjacent box beam bridges within INDOT’s bridge database were also analyzed. Superstructure ratings were compared with bridge age as well as bridge characteristics to highlight possible causes for deterioration. Analyzing the INDOT inventory, data shows that the condition of adjacent box beam bridges may be affected by location, type of wearing surface, and the use of deck membranes. Six bridges were then inspected to identify common deficiencies and specific problems. Exterior beams and beams within the wheel load path tend to have higher levels of deterioration. Furthermore, leaking joints between beams leads to corrosion of reinforcement, ultimately resulting in spalling, fracture of prestressing strands, and loss of structural capacity. Volume 2 focuses on evaluating the capacity of deteriorated adjacent box beams, the development of improved load rating procedures, and new box beam design. Through a series of bridge inspections, deteriorated box beams were identified and acquired for experimental testing. The extent of corrosion was determined through visual inspection, non-destructive evaluation, and destructive evaluation. Non-destructive tests (NDT) included the use of connectionless electrical pulse response analysis (CEPRA), ground penetrating radar (GPR), and half-cell potentials. Deteriorated capacity was determined through structural testing, and an analysis procedure was developed to estimate deteriorated behavior. A rehabilitation procedure was also developed to restore load transfer of adjacent beams in cases where shear key failures are suspected. Based on the understanding of deterioration developed through study of deteriorated adjacent box beam bridges, improved inspection and load rating procedures are provided along with design recommendations for the next generation of box beam bridges

Load Distribution of Adjacent Prestressed Concrete Box Beam Bridges

One of the most common bridge types is the adjacent prestressed concrete box beam bridge because the system is economical and simple to build; over 43,000 are currently in service within the US. However, they are highly susceptible to strand corrosion and concrete deterioration which can result in early loss of load capacity. Therefore, an experimental program sponsored by the Indiana Department of Transportation (INDOT) was initiated to determine the behavior of deteriorated beams and develop recommendations for load rating and design of this bridge type. Displacement sensors were installed on a bridge in service to measure its deformation under load. Modifications of the bridge condition were made in phases. These phases included the initial condition, removal of the asphalt layer, cutting of the shear keys (beam joint), and construction of a concrete deck. The bridge used in this project was constructed of seven adjacent box beams, with a length of forty feet. Finally, after comparing the results, the change in load distribution was evaluated to determine how much the shear keys contribute to this, and if the addition of a concrete deck was an appropriate rehabilitation solution for the structure

Repair and Strengthening of Bridges in Indiana Using Fiber Reinforced Polymer Systems: Volume 2–FRP Flexural Strengthening and End Region Repair Experimental Programs

For bridges that are experiencing deterioration, action is needed to ensure the structural performance is adequate for the demands imposed. Innovate repair and strengthening techniques can provide a cost-effective means to efficiently and safely extend the service lives of bridges. The use of fiber reinforced polymer (FRP) systems for the repair and strengthening of concrete bridges is increasing in popularity. Recognizing the potential benefits of the widespread use of FRP, a research project was initiated to determine the most appropriate applications of FRP in Indiana and provide recommendations for the use of FRP in the state for the repair and strengthening of bridges. The details of the research are presented in two volumes. Volume 1 provides the details of a study conducted to (i) summarize the state-of-the-art for the application of FRP to concrete bridges, (ii) identify successful examples of FRP implementation for concrete bridges in the literature and examine past applications of FRP in Indiana through case studies, and (iii) better understand FRP usage and installation procedures in the Midwest and Indiana through industry surveys. Volume 2 presents two experimental programs that were conducted to develop and evaluate various repair and strengthening methodologies used to restore the performance of deteriorated concrete bridge beams. The first program investigated FRP flexural strengthening methods, with focus placed on adjacent box beam bridges. The second experimental program examined potential techniques for repairing deteriorated end regions of prestressed concrete bridge girders. Externally bonded FRP and near-surface-mounted (NSM) FRP were considered in both programs