Effects of deposition temperature on microstructure of laminated (SiC-C) matrix composites

The microstructure of fiber-reinforced laminated SiC-C matrix composites has been studied using scanning and transmission electron microscopy (SEM and TEM) techniques. Different regions of the composites were found to exhibit microstructural differences due to the temperature gradient imposed during composite fabrication by the forced-flow thermal-gradient chemical vapor infiltration process. The matrix layers of alternating Carbon and SiC were found to be thicker but less clearly defined in the higher-temperature regions than in the lower-temperature regions. This feature was found to be more pronounced with increasing distance from the fiber surface. The medium temperature region was found to represent the intermediate point in the microstructural development of this composite. Possible qualitative explanations for the observed microstructural differences are suggested in the context of the temperature gradient and other process parameters employed.     

Cellular and Exosomal Regulations of Sepsis-Induced Metabolic Alterations

Sepsis is a sustained systemic inflammatory condition involving multiple organ failures caused by dysregulated immune response to infections. Sepsis induces substantial changes in energy demands at the cellular level leading to metabolic reprogramming in immune cells and stromal cells. Although sepsis-associated organ dysfunction and mortality have been partly attributed to the initial acute hyperinflammation and immunosuppression precipitated by a dysfunction in innate and adaptive immune responses, the late mortality due to metabolic dysfunction and immune paralysis currently represent the major problem in clinics. It is becoming increasingly recognized that intertissue and/or intercellular metabolic crosstalk via endocrine factors modulates maintenance of homeostasis, and pathological events in sepsis and other inflammatory diseases. Exosomes have emerged as a novel means of intercellular communication in the regulation of cellular metabolism, owing to their capacity to transfer bioactive payloads such as proteins, lipids, and nucleic acids to their target cells. Recent evidence demonstrates transfer of intact metabolic intermediates from cancer-associated fibroblasts via exosomes to modify metabolic signaling in recipient cells and promote cancer progression. Here, we review the metabolic regulation of endothelial cells and immune cells in sepsis and highlight the role of exosomes as mediators of cellular metabolic signaling in sepsis.     

Effects of admission and treatment strategies of DWI courts on offender outcomes

Purpose

The purpose of this study is to classify DWI courts on the basis of the mix of difficult cases participating in the court (casemix severity) and the amount of involvement between the court and participant (service intensity). Using our classification typology, we assessed how casemix severity and service intensity are associated with program outcomes. We expected that holding other factors constant, greater service intensity would improve program outcomes while a relatively severe casemix would result in worse program outcomes.

Methods

The study used data from 8 DWI courts, 7 from Michigan and 1 from North Carolina. Using a 2-way classification system based on court casemix severity and program intensity, we selected participants in 1 of the courts, and alternatively 2 courts as reference groups. Reference group courts had relatively severe casemixes and high service intensity. We used propensity score matching to match participants in the other courts to participants in the reference group court programs. Program outcome measures were the probabilities of participants’: failing to complete the court's program; increasing educational attainment; participants improving employment from time of program enrollment; and re-arrest.

Results

For most outcomes, our main finding was that higher service intensity is associated with better outcomes for court participants, as anticipated, but a court's casemix severity was unrelated to study outcomes.

Conclusions

Our results imply that devoting more resources to increasing duration of treatment is productive in terms of better outcomes, irrespective of the mix of participants in the court's program.     

Modeling Nitrogen Dynamics under Maize on Ferralsols in Western Africa

Mathematical models may be applied to simulate nitrogen (N) dynamics under different types of soil and environmental conditions to assess fertilizer N needs or to predict nitrate-N (NO₃–N) potential impact on water quality. The research version of LEACHMN was evaluated using data from lysimeters and field experiments conducted at the University of Lomé Research Farm in Togo, West Africa. The model was calibrated for the mineralization, nitrification, denitrification and volatilization rate constants with measured values of NO₃–N leaching losses and maize (Zea mays L.) N uptake collected from the lysimeter experiment. The model was then tested against measured data of soil profile NO₃–N distribution and maize N uptake from the field experiment and drainage water collected from the lysimeter experiment. The testing procedure involved two scenarios with increasing level of generalization for transformation rate constants (i) rate constant values for each N treatment and (ii) rate constant values averaged over N treatments. LEACHMN effectively simulated drainage water volume and rate (r²= 0.94 to 0.99). During the calibration efforts, the model satisfactorily simulated NO₃–N leaching losses (r²= 0.98) and accurately simulated growing season cumulative maize N uptake. The variation of the calibrated rate constants among N treatments was primarily linked to the model's incapacity to accurately simulate maize N uptake throughout the growing period. When tested using calibrated rate constants for each treatment, the model was successful in simulating soil profile NO₃–N distribution (r² = 0.52 to 0.94). Simulations of soil profile NO₃–N distribution were not satisfactory (r²= 0.03 to 0.49) when rate constants were averaged over N treatments. Improvement of the plant N uptake routine of the model is needed to increase the model’s performance. Using the LEACHMN model to predict N dynamics on the Ferralsols of southern Togo appears feasible when appropriate calibrations are performed.     

A comparison between the life cycle cost of gravel and of bituminous surfacing options for feeder roads in Ghana

Feeder roads, which constitute a key component of rural transport infrastructure, play a vital role in rural development, but only 5% of the total feeder road network in Ghana has bituminous seal surfacing. The remaining 95% have either gravel or earth surfacing. However, gravel surfacing (G-S) is known to deteriorate rather rapidly necessitating expensive frequent maintenance while bituminous surfacing offers a more durable surfacing. Various life cycle cost studies have suggested that even though G-S may have lower initial construction costs, they tend to have higher life cycle costs than bituminous seal surfaced ones. However, since most of these studies are based on ideal maintenance practices, their conclusions do not reflect actual field conditions. This study seeks therefore to compare the life cycle cost of G-S with that of bituminous seal surfacing options for engineered feeder roads in Ghana using actual cost data. Data were collected from eight feeder road projects with G-S and a similar number with bituminous surfacing from six regions of Ghana completed between 2010 and 2013. The life cycle cost for each road was computed using a discount rate of 12% and an inflation rate of 15% over an analysis period of 21 years. The results for G-S are then compared with those for single bituminous seal surfacing and for double bituminous seal surfacing. The results are further compared with those from trial sections of an experimental study of Otta seal surfacing using natural gravel and using crushed rock as aggregates. The results suggest that based on the high initial construction costs of bituminous seal surfacing and actual low maintenance intervention practices, G-S remain the least cost option. The study recommends the need for alternative surfacing technology that does not involve bitumen.     

How Much Extra Affordable Housing is Needed in England?

Booming housing markets in the UK have once again brought into sharper focus the issues of housing affordability, housing need and ‘affordable housing’ solutions. This paper reviews issues in the measurement of problems of affordability, particularly access to homeownership, and reports on modelled estimates for England at regional and local levels. These models provide a method for comparing pressures in different areas, but also for measuring market change over time and its relationship with the economy. They are also useful for identifying and assessing the scope for ‘intermediate’ forms of provision between conventional homeownership and social renting. Measures of recent and prospective needs for additional affordable housing provision, derived from this analysis of affordability, are presented and assessed. These findings are linked to a broader contemporary policy debate about housing and planning policy in England.