Low Cost Dewatering of Waste Slurries

The U.S. Bureau of Mines has developed a technique for dewatering mineral waste slurries which utilizes polymer and a static screen. A variety of waste slurries from placer gold mines and crushed stone operations have been successfully treated using the system. Depending on the waste, a number of polymers have been used successfully with polymer costs ranging from $0.05 to$0.15 per 1,000 gal treated. The dewatering is accomplished using screens made from either ordinary window screen or wedge wire. The screens used are 8 ft wide and 8 ft long. The capacity of the screens varies from 3 to 7 gpm/sq. ft. The water produced is acceptable for recycling to the plant or for discharge to the environment. For example, a fine grain dolomite waste slurry produced from a crushed stone operation was dewatered from a nominal 2.5 pct solids to greater than 50 pct solids using $0.10 to$0.15 worth of polymer per 1,000 gal of slurry. The resulting waste water had a turbidity of less than 50 NTU and could be discharged or recycled. The paper describes field tests conducted using the polymer-screen dewatering system

Studying patterns of use of transport modes through data mining - Application to U.S. national household travel survey data set

Data collection activities related to travel require large amounts of financial and human resources to be conducted successfully. When available resources are scarce, the information hidden in these data sets needs to be exploited, both to increase their added value and to gain support among decision makers not to discontinue such efforts. This study assessed the use of a data mining technique, association analysis, to understand better the patterns of mode use from the 2009 U.S. National Household Travel Survey. Only variables related to self-reported levels of use of the different transportation means are considered, along with those useful to the socioeconomic characterization of the respondents. Association rules potentially showed a substitution effect between cars and public transportation, in economic terms but such an effect was not observed between public transportation and nonmotorized modes (e.g., bicycling and walking). This effect was a policy-relevant finding, because transit marketing should be targeted to car drivers rather than to bikers or walkers for real improvement in the environmental performance of any transportation system. Given the competitive advantage of private modes extensively discussed in the literature, modal diversion from car to transit is seldom observed in practice. However, after such a factor was controlled, the results suggest that modal diversion should mainly occur from cars to transit rather than from nonmotorized modes to transi

Solar spectral conversion for improving the photosynthetic activity in algae reactors

Sustainable biomass production is expected to be one of the major supporting pillars for future energy supply, as well as for renewable material provision. Algal beds represent an exciting resource for biomass/biofuel, fine chemicals and CO2 storage. Similar to other solar energy harvesting techniques, the efficiency of algal photosynthesis depends on the spectral overlap between solar irradiation and chloroplast absorption. Here we demonstrate that spectral conversion can be employed to significantly improve biomass growth and oxygen production rate in closed-cycle algae reactors. For this purpose, we adapt a photoluminescent phosphor of the type Ca 0.59Sr0.40Eu0.01S, which enables efficient conversion of the green part of the incoming spectrum into red light to better match the Qy peak of chlorophyll b. Integration of a Ca 0.59Sr0.40Eu0.01S backlight converter into a flat panel algae reactor filled with Haematococcus pluvialis as a model species results in significantly increased photosynthetic activity and algae reproduction rate

Hydrogen bonding in infinite hydrogen fluoride and hydrogen chloride chains

Hydrogen bonding in infinite HF and HCl bent (zigzag) chains is studied using the ab initio coupled-cluster singles and doubles (CCSD) correlation method. The correlation contribution to the binding energy is decomposed in terms of nonadditive many-body interactions between the monomers in the chains, the so-called energy increments. Van der Waals constants for the two-body dispersion interaction between distant monomers in the infinite chains are extracted from this decomposition. They allow a partitioning of the correlation contribution to the binding energy into short- and long-range terms. This finding affords a significant reduction in the computational effort of ab initio calculations for solids as only the short-range part requires a sophisticated treatment whereas the long-range part can be summed immediately to infinite distances.Comment: 9 pages, 4 figures, 3 tables, RevTeX4, corrected typo

Computational Insights into Mg-Cl Complex Electrolytes for Rechargeable Magnesium Batteries

DFT calculations were conducted to provide insightful and unprecedented thermodynamic insights on tetrahydrofuran (THF) solvation, isomerization, chlorination, and complexation of possible Mg-Cl coordination species for the popular Mg-Cl electrolytes. Computational results using the M06-2x functional with the 6-31+G(d) basis set indicate trigonal bipyramidal e, e-cis-tbp-MgCl2(THF)3 dichloride species and octahedral [MgCl(THF)5]+ monochloride species are the dominant mononuclear species. These two can combine to form the active dinuclear species, [(μ-Cl)3Mg2(THF)6]+ with a free energy -6.30 kcal/mol, which is calculated to be the dominant Mg-Cl species in solution. Two mono-cation species, [(μ-Cl)3Mg2(THF)6]+ and [MgCl(THF)5]+ have comparable LUMO energies, thus both of them can act as active species for Mg deposition. However, the significant dominance of the dinuclear species in the electrolyte indicates that it is the primary species involved in reversible Mg deposition

Life events and travel behavior exploring the interrelationship using UK Household Longitudinal Study data

Recent research has indicated that changes in travel behavior are more likely at the time of major life events. However, much remains to be learned about the extent to which different life events trigger behavioral change and the conditions under which life events are more likely to trigger change. The UK Household Longitudinal Study (UKHLS) offers a previously unavailable opportunity to investigate this topic for a large, representative sample of the UK population. UKHLS data were also linked to local spatial data drawn from the census and other sources to elucidate the effect of the spatial context on changes to travel behavior in association with life events. Findings from an exploratory analysis of data from UKHLS Waves 1 and 2 are presented first Transition tables demonstrate a strong association between changes in car ownership and commute mode and the following life events: employment changes, residential relocation, retirement, the birth of children, and changes in household structure. The results of logit models that relate the probability of an increase and a decrease in the number of cars owned to the occurrence of life events and that control for individual and household characteristics and spatial context are then shown. These models show, for example, that moves to urban and rural areas have contrasting effects on travel behavior and that having a new child in itself is not a significant influence on car ownership in the short term

An Exploration of the Ozone Dimer Potential Energy Surface

The (O3)2 dimer potential energy surface is thoroughly explored at the ab initio CCSD(T) computational level. Five minima are characterized with binding energies between 0.35 and 2.24 kcal/mol. The most stable may be characterized as slipped parallel, with the two O3 monomers situated in parallel planes. Partitioning of the interaction energy points to dispersion and exchange as the prime contributors to the stability, with varying contributions from electrostatic energy, which is repulsive in one case. Atoms in Molecules analysis of the wavefunction presents specific O⋯O bonding interactions, whose number is related to the overall stability of each dimer. All internal vibrational frequencies are shifted to the red by dimerization, particularly the antisymmetric stretching mode whose shift is as high as 111 cm−1. In addition to the five minima, 11 higher-order stationary points are identified

The Magnitude and Mechanism of Charge Enhancement of CH∙∙O H-bonds

Quantum calculations find that neutral methylamines and thioethers form complexes, with N-methylacetamide (NMA) as proton acceptor, with binding energies of 2–5 kcal/mol. This interaction is magnified by a factor of 4–9, bringing the binding energy up to as much as 20 kcal/mol, when a CH3+ group is added to the proton donor. Complexes prefer trifurcated arrangements, wherein three separate methyl groups donate a proton to the O acceptor. Binding energies lessen when the systems are immersed in solvents of increasing polarity, but the ionic complexes retain their favored status even in water. The binding energy is reduced when the methyl groups are replaced by longer alkyl chains. The proton acceptor prefers to associate with those CH groups that are as close as possible to the S/N center of the formal positive charge. A single linear CH··O hydrogen bond (H-bond) is less favorable than is trifurcation with three separate methyl groups. A trifurcated arrangement with three H atoms of the same methyl group is even less favorable. Various means of analysis, including NBO, SAPT, NMR, and electron density shifts, all identify the +CH··O interaction as a true H-bond

The impact of ABO blood type on the prevalence of portal vein thrombosis in patients with advanced chronic liver disease

Background and aimsNon-O blood type (BT) is a risk factor for thromboses, which has been attributed to its effects on von Willebrand factor (VWF)/factor VIII (FVIII) levels. Although high VWF/FVIII may be risk factors for portal vein thrombosis (PVT) in patients with advanced chronic liver disease (ACLD), the impact of BT on PVT is unknown. We aimed to assess (I) whether non-O-BT is a risk factor for PVT and (II) whether non-O-BT impacts VWF/factor VIII in patients with ACLD. MethodsRetrospective analysis comprising two cohorts: (I) "US" including all adult liver transplantations in the US in the MELD era and (II) "Vienna" comprising patients with a hepatic venous pressure gradient (HVPG) >= 6 mmHg. Results(I) The "US cohort" included 84 947 patients (non-O: 55.43%). The prevalence of PVT at the time of listing (4.37% vs 4.56%; P = .1762) and at liver transplantation (9.56% vs 9.33%; P = .2546) was similar in patients with O- and non-O-BT. (II) 411 patients were included in the "Vienna cohort" (non-O: 64%). Mean HVPG was 18(9) mmHg and 90% had an HVPG >= 10 mmHg. Patients with non-O-BT had slightly increased VWF levels (318(164)% vs 309(176)%; P = .048; increase of 23.8%-23.9% in adjusted analyses), but this difference was driven by patients with less advanced disease. However, non-O-BT explained only 1% of the variation in VWF and had no effect on FVIII. ConclusionsAlthough non-O-BT impacts VWF in patients with early stage ACLD, its contribution to VWF variation is considerably smaller than in the general population. Moreover, non-O-BT had no impact on FVIII. These findings may explain the absence of an association between non-O-BT and PVT in patients with advanced cirrhosis