Sustainable process design by the process to planet framework

Sustainable process design (SPD) problems combine a process design problem with life cycle assessment (LCA) to optimize process economics and life cycle environmental impacts. While SPD makes use of recent advances in process systems engineering and optimization, its use of LCA has stagnated. Currently, only process LCA is utilized in SPD, resulting in designs based on incomplete and potentially inaccurate life cycle information. To address these shortcomings, the multiscale process to planet (P2P) modeling framework is applied to formulate and solve the SPD problem. The P2P framework offers a more comprehensive analysis boundary than conventional SPD and greater modeling detail than advanced LCA methodologies. Benefits of applying this framework to SPD are demonstrated with an ethanol process design case study. Results show that current methods shift emissions outside the analysis boundary, while applying the P2P modeling framework results in environmentally superior process designs. Future extensions of the P2P framework are discussed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3320–3331, 2015     

Extraction Selectivities of Crown Ethers for Alkali Metal Cations: Differences between Single-Species and Competitive Solvent Extractions

Separation factor values for pairs of alkali metal cations determined in competitive solvent extractions of alkali metal picrates from aqueous solutions into chloroform by a variety of benzo- and cyclohexano-group-containing crown ethers vary significantly from extrapolations based upon the results of single-species extraction experiments. For almost all of the crown ether-alkali metal cation combinations examined, the separation factor values are greater for competitive solvent extraction. In view of the unexpected results for sodium picrate extraction by dibenzo-24-crown-8, the solid-state structure of the isolated complex was determined.     

Optimized excitation energy transfer in a three-dye luminescent solar concentrator

The spectral range of sunlight absorbed by a luminescent solar concentrator (LSC) is increased by using multiple dyes. Absorption, fluorescence, and fluorescence excitation spectra, and relative light output are reported for LSCs made with one, two, or three BODIPY dyes in a thin polymer layer on glass. Losses caused by multiple emission and reabsorption events are minimized by optimizing resonance excitation energy transfer between dyes. Increases in the outputs from the multiple-dye LSCs are directly proportional to increases in the number of photons absorbed. The output of the three-dye LSC is 45–170% higher than those of the single-dye LSCs.     

Attachment loss with postmenopausal age and smoking

To determine whether postmenopausal bone loss and factors associated with osteoporosis affect tooth retention, we examined vertebral and proximal femoral (postcranial) bone mineral density in relation to tooth loss and attachment loss in a cross-sectional study of 135 postmenopausal women (age range 41-70 yr). Women had at least 10 teeth and no evidence of moderate or severe periodontal disease. Full-mouth attachment loss measurements were made using a pressure-sensitive probe, and bone density was determined by dual-energy X-ray absorptiometry. Attachment loss was correlated with tooth loss (number of remaining teeth, radiologically determined), but not with vertebral or proximal femur bone density. Multivariate analysis showed current smoking (p = 0.01), years since menopause (p = 0.02) and the interaction of age and current smoking (p < 0.01), to be statistically significant predictors of attachment loss in our study population.     

Power grasp force distribution control using artificial neural networks

In this article, methods for force distribution control of power grasp are developed. A power grasp is characterized by multiple points of contact between the object grasped and the surfaces of the fingers and palm. The grasp is highly stable because of form closure. However, modeling power grasps is difficult because of the resulting closed kinematic structure and the complexity of multiple contacts. The first method used to obtain the desired force distribution is based on linear programming. In particular, a model of the DIGITS grasping system, under development at The Ohio State University, is used, and constraint equations are formulated for force balance and actuator torque limits. Supervisory control of the desired forces at the contacts is achieved by prescribing a desired clinch level. The objective function is designed to achieve the desired clinch level, except in cases where the specified force is inadequate to stably hold the object. Although this method yields the desired force distribution, a second method based on artificial neural networks (ANNs) is developed to achieve constant-time solutions. Linear programming solutions are used to generate training data for a set of ANNs. Two techniques, modular networks and adaptive slopes, are also developed and employed in the training to improve the training time and accuracy of the ANNs. The results show that the ANNs learn the appropriate nonlinear mapping for the force distribution and provide stable grasp over a wide range of object sizes and clinch levels.     

A relationship between proteinase activity and clinical parameters in the treatment of periodontal disease

The objective of this research was to determine the effectiveness of a biochemical assay which measures proteolytic enzyme activity in gingival crevicular fluid (GCF) and to relate this enzyme activity to clinical parameters traditionally utilized for periodontitis detection. A clinical trial was conducted on 8 periodontitis subjects with > or =4 sites exhibiting a loss of attachment of > or =5 mm and probing depths of > or =5 mm with bleeding on probing. On each subject, a plaque index was performed, followed by GCF sampling at those sites which exhibited a loss of attachment and probing depths. GCF was analyzed for activity against benzoyl-L-arginine-p-nitroanilide in the presence (BAPNA w/gly-gly) and the absence (BAPNA w/o gly-gly) of glycyl-glycine and against MeOSuc-Ala-Ala-Pro-Val-pNA and Suc-Ala-Ala-Pro-Phe-pNA for neutrophil serine proteinases activity (elastase and cathepsin G, respectively). Subsequently, a gingival index was performed, attachment levels and probing depths were recorded using a constant force probe with bleeding on probing being noted. A split-mouth design was employed and half mouths were randomly assigned to the following treatment groups: group A, half of the mouth received scaling/root planing and polishing: group B, half of the mouth received no treatment (control). Subjects were treated, then instructed on toothbrushing and interdental cleaning. After 4 weeks, subjects returned to receive a plaque index; GCF sampling, gingival index, attachment levels, probing depths and bleeding on probing as described above. Using a paired Student t-test, the findings suggest that BAPNA w/gly-gly was significantly less in treatment sites than in non-treated control sites (p=0.05). No such correlation was found for other activities, including neutrophil serine proteinases which were shown to occur in GCF in free, proteolytically active forms. In addition, significant treatment effects were detected for probing depths (p= 0.03) which reduced by 1.3 mm and attachment levels (p=0.02) which gained 0.7 mm. The reduction of P. gingivalis from treated periodontitis sites as detected by a significant decrease in BAPNA w/ gly-gly may prove to be a valuable marker for periodontal disease activity.     

Factors Affecting the Permanence of Occupational Health and Safety Topics in Engineering Courses

This paper presents an evaluation of the permanence of changes introduced within the curriculum of the College of Engineering at Tufts University. These changes involved the integration of occupational health and safety engineering resource materials into existing course work. Employing this model, Tufts faculty members developed their own lectures, case studies and laboratory materials for integration into existing courses. The evaluation, that was based on structured interviews of participating faculty and the Dean of the College, suggests that the permanence of changes to curriculum is influenced by a set of intramural parameters within the academic milieu (student interest, available class time, interest on the part of the faculty and administration) as well as by extramural factors such as the increasing prominence of legal liability of practitioners, growing interest on the part of employers and lack of readily usable materials in standard texts concerning occupational health and safety. Recommendations for future activities in these areas are offered and discussed.     

Frequency of a methane-stabilized helium-neon laser

A phase-locked laser frequency chain was used to measure the absolute frequency of a HeNe/CH₄ laser relative to the primary Cs standard, with measurement uncertainty less than ±1 part in 10¹². The frequency depends on laser parameters; a spread of 8.3×10^-11 was observed. This was attributed to the variation of Lamb dip asymmetry resulting from the gas-lens effect and the accompanying diffraction loss variation near resonance. Means of improving laser frequency reproducibility by reducing cavity diffraction loss variation were studied experimentally. The frequency obtained with a cavity exhibiting the smallest Lamb dip asymmetry was found to be 88 376 181 599.07±0.07 kHz     

Hypertension in African Americans: a paradigm of metabolic disarray

Hypertensive disease in African Americans manifests itself at an earlier age, tends to be more aggressive and difficult to treat, and is more likely to be associated with renal failure. Abnormalities of carbohydrate metabolism, specifically tissue insulin resistance, may underlie the constellation of clinical and pathophysiological characteristics commonly observed in African American hypertensive subjects. The interrelationships between insulin resistance, salt sensitivity, and vascular hyperresponsitivity to adrenergic stimuli require further clinical study, because this relationship may not only partly explain much of the hypertensive disease observed in African Americans, but may also help identify appropriate therapeutic interventions.     

The role of a 40-megadalton plasmid in the adherence and hemolytic properties of Aeromonas hydrophila

Thirty ventilation-perfusion pulmonary scintigraphic studies were performed in 13 patients who had undergone unilateral lung transplantation. Ventilation-perfusion mismatch (ventilation better than perfusion) was judged absent, mild, moderate, or severe in the transplanted and native lungs. Ventilation-perfusion mismatch was significantly worse in the transplanted lungs (p < .0001). Findings of lung biopsies and chest roentgenograms failed to correlate with the severity of ventilation-perfusion mismatch. Hypoxic pulmonary vasoconstriction appears to be significantly impaired in most unilateral lung transplants; the mechanism for this impairment is unclear.