The relationship between green chemistry and sustainable cement production and use is examined. Some alternative cement are reviewed and compared to blended ordinary Portland cements in terms of ...their chemistry and properties. Improving the cement within concrete is an essential part of addressing these concerns. While Portland cement manufacture and use can still undergo slight environmental improvements, great opportunities lie in the utilization of cement based on alternative compositions, binding-phases and green chemistry. This allows cement to be synthesized from a variety of materials including recycled resources and mineral wastes, which reduces the energy demands during production. Emphasis is given to the material properties, durability, performance and applications of the "greener" alternative cements. It is clear that alternative cements have considerable potential in terms of environmental, engineering and economic properties.
We present the performance characteristics of a digital output thin-film pyroelectric sensor for use in non-dispersive infra-red detection. The single channel pyroelectric sensor device was fitted ...with band-pass optical filter with a central wavelength of <inline-formula> <tex-math notation="LaTeX">4.26~\mu \text{m} </tex-math></inline-formula> for the detection of carbon dioxide. The classification reported here is concerned with the stability of the device for long-term measurements, with systematic drift not dominating measurement error even after 10 h operation. Comparative NDIR measurements were made for this novel pyroelectric device using two different optical sources, a standard filament lamp and a black body radiation source, operated at 5 Hz repetition rates. The overall limit of detection for the NDIR sensor was calculated to be 6 and 3 ppm for CO 2 for the filament and blackbody source respectively, when the sensor was temperature stabilised at 35 °C and data was averaged over 110 min. The single shot measurement error was calculated to be 48 and 22 ppm for the lamp and blackbody, respectively, when the sensor temperature was stabilised at 35°C. The response of the detector to increasing temperature was found to exhibit a trend in the signal output directly proportional to the pyroelectric coefficient, this was also evident during flow tests when the flowing gas cooled the device. The result of changing both the concentration of analyte and flow rate is also covered. This is the first time the performance of a fully digital output pyroelectric detector has been reported.
Adults aging with HIV infection are at risk for age-related comorbidities and syndromes, such as frailty. The objective of this study was to evaluate the expression and predictors of the frailty ...phenotype (FP) among HIV-infected (HIV+) and HIV-uninfected (HIV-) men who have sex with men.
A prospective, observational cohort study was nested in the Multicenter AIDS Cohort Study from October 2007-September 2011. FP conversion was defined as the onset of FP over two consecutive study visits. Adjusted odds ratios and 95% confidence intervals (,) for FP conversion were estimated using logistic regression models with generalized estimating equations.
Of 10,571 completed study visits from 1,946 men who have sex with men, 12% and 9% were FP+ among HIV+ and HIV- men, respectively (p = .002). The proportion of FP+ visits increased with age regardless of HIV status, but was significantly greater in HIV+ compared to HIV- men aged 50-64 years. Of the 10,276 consecutive visit pairs contributed by participants, 5% (537) were classified as FP conversion, and 45% of the men with FP conversion had only one FP+ study visit. FP conversion was significantly associated with a history of AIDS (adjusted odds ratios = 2.26 1.50, 3.39, but not with HIV+ alone (adjusted odds ratios = 1.26 0.98, 1.64). Among men who had one or more FP+ visits, 34% of HIV+ and 38% of HIV- men had less than two comorbidities.
These findings suggest that expression of the FP can be measured in men who have sex with men with and without HIV infection and reflects multisystem dysfunction in this population; further investigations are needed to better understand clinical utility.
Hydrogen separation membrane devices are attracting increasing interest for the industrial production of hydrogen. Metal membranes, in particular, are promising due to their resilience to the demands ...of a typical hydrogen purification process. However, the use of too much Pd within the membranes limits their wide-scale industrial use due to excessive costs. The present article reviews the design, preparation, operation, and critical performance features of novel non-Pd-based alloys. The theory behind the permeation of hydrogen through metal membranes is presented as well as the materials and methods central to their design and improvement. Crystalline, amorphous, and thin layer metal membranes are contrasted, while the advanced experimental techniques and mechanical tests for their characterization are discussed. The review considers the design of novel metal membranes from first principles and assesses catalytic and protective surface layers which may enhance their hydrogen separation capabilities.
Parametric and semiparametric competing risks methods were used to estimate proportions, timing, and predictors of acquired immune deficiency syndrome (AIDS)-related and non-AIDS-related mortality ...among individuals both positive and negative for the human immunodeficiency syndrome (HIV) in the Multicenter AIDS Cohort Study (MACS) and Women's Interagency HIV Study (WIHS) from 1984 to 2008 and 1996 to 2008, respectively. Among HIV-positive MACS participants, the proportion of deaths unrelated to AIDS increased from 6% before the introduction of highly active antiretroviral therapy (HAART) (before 1996) to 53% in the HAART era (P < 0.01); the median age of persons who died from non-AIDS-related causes after age 35 years increased from 49.0 to 66.0 years (P < 0.01). In both cohorts during the HAART era, median ages at time of non-AIDS-related death were younger for HIV-positive individuals than for comparable HIV-negative individuals (8.7 years younger in MACS (P < 0.01) and 7.6 years younger in WIHS (P < 0.01)). In a multivariate proportional cause-specific hazards model, unemployment (for non-AIDS death, hazard ratio (HR) = 1.8; for AIDS death, HR = 2.3), depression (for non-AIDS death, HR = 1.4; for AIDS death, HR = 1.4), and hepatitis B or C infection (for non-AIDS death, HR = 1.8, for AIDS death; HR = 1.4) were significantly (P < 0.05) associated with higher hazards of both non-AIDS and AIDS mortality among HIV-positive individuals in the HAART era, independent of study cohort. The results illuminate the changing face of mortality among the growing population infected with HIV.
Background. Older healthy and HIV-infected adults exhibit physiological similarities. Frailty is a clinical syndrome associated with aging that identifies a subset of older adults at high risk of ...mortality and other outcomes. We investigated whether HIV infection increases the prevalence of a frailty-related phenotype (FRP) that approximates a clinical definition of frailty. Methods. We first defined the FRP and assessed its prevalence among HIV-uninfected men followed in the Multicenter AIDS Cohort Study (MACS) between 1994 and 2004. Using repeated measurements logistic regression models, we then assessed the association between FRP and HIV infection before the era of highly active antiretroviral therapies, adjusting for covariates among HIV-uninfected (N = 1905) and incident HIV cases (N = 245). Results. HIV infection was strongly associated with FRP prevalence. Compared to HIV-uninfected men of similar age, ethnicity and education, HIV-infected men were more likely to have the FRP for all durations of infection: for ≤4 years, the adjusted odds ratio (OR) was 3.38, with 95% confidence interval (CI), 1.25–9.11, and for 4.01–8 years and 8.01–12 years the corresponding figures were (OR = 12.95, 95% CI, 6.60–25.40) and (OR = 14.68, 95% CI, 7.60–28.35), respectively. The FRP prevalence for 55-year-old men infected with HIV for ≤4 years (3.4%; 95% CI, 1.3–8.6) was similar to that of uninfected men ≥65 years old (3.4%; 95% CI, 1.5–7.6). Conclusion. In this cohort, HIV infection was associated with an earlier occurrence of a phenotype that resembles the phenotype of frailty in older adults without HIV infection. Studies of frailty in the setting of HIV infection may help to clarify the biological mechanism of frailty.
CONTEXT:Immunological similarities have been noted between HIV-infected individuals and older HIV-negative adults. Immunologic alterations with aging have been noted in frailty in older adults, a ...clinical syndrome of high risk for mortality and other adverse outcomes. Using a frailty-related phenotype (FRP), we investigated in the Multicenter AIDS Cohort Study whether progressive deterioration of the immune system among HIV-positive individuals independently predicts onset of FRP.
METHODS:FRP was evaluated semiannually in 1046 HIV-infected men from 1994 to 2005. CD4 T-cell count and plasma viral load were evaluated as predictors of FRP by logistic regression (generalized estimating equations), adjusting for age, ethnicity, educational level, AIDS status, and treatment era pre-highly active antiretroviral therapy (HAART) (1994-1995) and HAART (1996-1999 and 2000-2005).
RESULTS:Adjusted prevalences of FRP remained low for CD4 T-cell counts >400 cells per cubic millimeter and increased exponentially and significantly for lower counts. Results were unaffected by treatment era. After 1996, CD4 T-cell count, but not plasma viral load, was independently associated with FRP.
CONCLUSIONS:CD4 T-cell count predicted the development of a FRP among HIV-infected men, independent of HAART use. This suggests that compromise of the immune system in HIV-infected individuals contributes to the systemic physiologic dysfunction of frailty.
The unplanned 30-day readmission rate is a marker of quality of patient care across many disciplines. Data regarding risk factors for unplanned readmission after major lower extremity amputation ...(LEA) are limited. We evaluated predictors of readmission at our institution after major LEA.
We conducted a retrospective review of all patients undergoing above-knee amputation (AKA) or below-knee amputation (BKA) between November 2009 and November 2014. Patient demographic variables were collected. Predictors of unplanned 30-day readmission and stump complications were determined by multivariable logistic regression.
A total of 811 patients were identified (AKA, 325; BKA, 486). Of these, 739 patients were included in the final analysis after excluding 30-day decedents without readmission. The overall 30-day readmission rate was 28.8% (AKA 27.9%; BKA 29.4%; P = .730). Stump complications accounted for 28.6% of readmissions (16.5% of AKA; 35.8% of BKA; P = .004). Other common diagnoses included nonsurgical site infection (33.8%), exacerbation of congestive heart failure (7.0%), and diabetes-related complications (6.1%). Surgical intervention was performed on 61% of stump complications (35.9% of AKA readmitted with stump complications; 68.7% of BKA readmitted with stump complications). BKA stump complications were converted to AKAs in 34.1% of cases (3.2% of the total BKA). None of the AKA stump complications required a higher level of amputation (ie, hip disarticulation). Independent predictors of all 30-day readmission included coronary artery disease and end-stage renal disease. American Society of Anesthesiologists class 3 as compared with class 4 was protective. Independent predictors of 30-day readmission for stump complications included rest pain and BKA. Patients who underwent BKA, rest pain as an indication for amputation, and having an occluded bypass graft were predictors of having a stump complication requiring surgery.
The 30-day readmission rate after major LEA is high, with wound infections accounting for a significant proportion of these readmissions. There was no difference in readmission rates based on level of amputation. Those undergoing BKA were more likely to present with stump complications requiring a surgical intervention, and often a higher level of amputation. Identification of high-risk patients may play a role in reducing postoperative readmissions and stump complications.
UO1-AI-35041: To examine the impact of HIV infection and highly active antiretroviral therapy on systolic and diastolic hypertension.
Cohort study with semi-annual assessment of the outcome.
We ...studied 5578 participants of the Multicenter AIDS Cohort Study with blood pressure measurements obtained between 1984 and 2003. The primary outcomes were systolic hypertension (SH; systolic blood pressure > 140 mmHg) and diastolic hypertension (DH; diastolic blood pressure > 90 mmHg). Statistical analyses were performed using multiple logistic regression with robust variance estimation.
Of the 84 813 person-visits available for analysis, 7.3 and 8.0% showed SH and DH, respectively. Controlling for age, race, body mass index, and smoking, HIV positive men not taking antiretroviral therapy were significantly less likely than HIV negative men to have SH odds ratio (OR), 0.79; 95% confidence interval (CI), 0.70-0.89, as were men taking mono/combination therapy (OR, 0.69; 95% CI, 0.59-0.80). The prevalence of SH among men taking highly active antiretroviral therapy (HAART) for less than 2 years was similar to that among HIV negative men (OR, 1.06; 95% CI, 0.87-1.30), but was significantly higher thereafter; for 2 to 5 years of HAART (OR, 1.51; 95% CI, 1.25-1.82) and for more than 5 years of HAART (OR, 1.70; 95% CI, 1.34-2.16). In contrast, DH was not significantly higher among men with prolonged HAART use compared to that among HIV negative controls.
Prolonged HAART use was significantly associated with a higher prevalence of SH. This finding suggests that individuals taking HAART may be at increased risk of developing hypertension-related conditions and underscores the importance of blood pressure monitoring among these individuals.
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