Effect of Organic Surface Load on Process Performance of Pilot-Scale Algae and Duckweed-Based Waste Stabilization Ponds

Removal efficiencies in pilot scale algae-based ponds (ABPs) and duckweed-based ponds (DBPs) were assessed during two periods of 4 months each. During Periods 1 and 2, the effect of low and high organic loading was studied. A linear correlation between ponds organic surface loading rates and the corresponding biochemical oxygen demand (BOD) removal rates was observed in both systems. For both periods, higher BOD and total suspended solids (TSS) removal efficiencies were found in DBPs compared to ABPs. Nitrogen removal rates (λr) in ABPs were linearly correlated with BOD surface loading rates (λs,BOD) and nitrogen loading rates (λs,N), while in DBPs, N removal rates were almost constant irrespective of λs,BOD or λs,N. Overall N removal rate in the algae system was significantly higher than that in duckweed system. Organic loading had no effect on total phosphorus removal efficiency in both systems. Higher P removal efficiency was achieved in the duckweed system than in the algae system. In ABPs as well as DBPs, fecal coliforms were better removed during low organic loading in comparison with high organic loading. During the two operational periods, higher fecal coliform removal efficiency in the algae system than in the duckweed system was observed.     

Induced hypothermia in critical respiratory failure after lung transplantation

A practical approach to detect and identify ceftazidime-hydrolyzing extended-spectrum mutants of OXA-10 beta-lactamase is presented. Large numbers of bacteria were screened by colony hybridization, a 720-bp part of blaOXA was amplified by PCR from the hybridization-positive isolates, and the products were digested by PvuII and HaeIII.     

Caring for a family member with a traumatic brain injury

The responses to a questionnaire on subjective burden are reported for 52 primary caregivers of a group of persons with traumatic brain injuries sustained an average of 6 years previously. The aim of the study was to examine satisfaction with social support, perception of coping skills, and appraisal of symptoms as predictors of strain in the carers. A range of responses, both positive and negative, to the work of caring for a relative with a head injury was reported. A high prevalence rate of emotional and behavioural changes in the persons with head injuries was found and the amount of distress caused by these symptoms was found to be predictive of burden. The other factor important in predicting burden was the carers' ratings of their satisfaction with their ability to cope with the work of caregiving. Social support, injury severity, and the demographic characteristics of the persons with head injury and their carers were not significant predictors. Depression in the carers was also investigated and the variable most predictive of elevated depression scores was coping satisfaction. These findings reinforce the importance of strengthening carers coping resources in rehabilitation work with head injured persons and their families.     

GENOMIC HARDWIRING AND PHENOTYPIC PLASTICITY OF TERPENOID-BASED DEFENSES IN CONIFERS

Over evolutionary history, conifers have faced a myriad of threats from phloem- and xylem-feeding insects, defoliating insects, and fungal pathogens. Among the trees defenses, terpenoids appear to play a major role by harming, disabling, deterring, repelling, or otherwise reducing the fitness of potential invaders. Each of the three classes of terpenoids in conifers, monoterpenes, sesquiterpenes, and diterpenes, are composed of a large number of representative compounds. In most cases, the presence of a particular terpenoid compound in the oleoresin or volatile emissions from a specific conifer can be accounted for by the expression of one of many committed terpene synthase (TPS) genes. However, while each TPS may produce one or a few major products, many produce a variety of minor products with relatively constant component ratios in the product blends. TPS genes exist in conifers in large and functionally diverse, yet monophyletic, gene families. Within these gene families, new biochemical functions of TPS appear to have evolved by gene duplication and changes in the amino acid sequence of the enzymes active site. In addition, TPS genes may be differentially expressed prior to, during, and following attack by insects or pathogens. Thus, while the production of any particular terpenoid is hardwired into a conifers genome, these trees have the capacity to change the mixture of terpenoids in oleoresin secretions and volatile emissions. Anatomical changes may also accompany induced terpenoid production, supplementing the plasticity of the molecular and biochemical events.     

Study of the coupling reactions between electrochemically generated aromatic radical anions and methyl, alkyl and benzyl radicals

Alkyl radicals produced in the indirect reduction of alkyl halides or alkyldimethylsulfonium salts by electrochemically generated aromatic radical anions couple fast with the latter and alkylated or dialkylated dihydro compounds are formed. Rate constants measured for the coupling reaction between on one hand methyl, primary, secondary and tertiary alkyl radicals as well as benzyl and cumyl radicals and on the other hand a wide spectrum of electrochemically generated aromatic radical anions are found to be about 1×10⁹ M⁻¹ s⁻¹. Previous measurements of coupling rate constants for primary alkyl radicals have been re-evaluated since they were affected by the presence of an S_N2 reaction occurring between the alkyl halides used as radical precursors and the aromatic radical anions. New experiments are also included using alkyldimethylsulfonium salts as precursors in order to prevent such S_N2 artefacts. It is concluded that sterical hindrance does not play a significant role for the radical-radical anion coupling reactions. In general the rate constants for the coupling reactions are all close to 10⁹ M⁻¹ s⁻¹.     

Competing risks as a multi-state model

This paper deals with the competing risks model as a special case of a multi-state model. The properties of the model are reviewed and contrasted to the so-called latent failure time approach. The relation between the competing risks model and right-censoring is discussed and regression analysis of the cumulative incidence function briefly reviewed. Two real data examples are presented and a guide to the practitioner is given.     

Temporal aggregation and spurious instantaneous causality in multiple time series models

Large aggregation interval asymptotics are used to investigate the relation between Granger causality in disaggregated vector autoregressions (VARs) and associated contemporaneous correlation among innovations of the aggregated system. One of our main contributions is that we outline various conditions under which the informational content of error covariance matrices yields insight into the causal structure of the VAR. Monte Carlo results suggest that our asymptotic findings are applicable even when the aggregation interval is small, as long as the time series are not characterized by high levels of persistence.     

No effect of creatine supplementation on oxidative stress and cardiovascular parameters in spontaneously hypertensive rats

Background

Exacerbated oxidative stress is thought to be a mediator of arterial hypertension. It has been postulated that creatine (Cr) could act as an antioxidant agent preventing increased oxidative stress. The aim of this study was to investigate the effects of nine weeks of Cr or placebo supplementation on oxidative stress and cardiovascular parameters in spontaneously hypertensive rats (SHR).

Findings

Lipid hydroperoxidation, one important oxidative stress marker, remained unchanged in the coronary artery (Cr: 12.6 ± 1.5 vs. Pl: 12.2 ± 1.7 nmol·mg^-1; p = 0.87), heart (Cr: 11.5 ± 1.8 vs. Pl: 14.6 ± 1.1 nmol·mg^-1; p = 0.15), plasma (Cr: 67.7 ± 9.1 vs. Pl: 56.0 ± 3.2 nmol·mg^-1; p = 0.19), plantaris (Cr: 10.0 ± 0.8 vs. Pl: 9.0 ± 0.8 nmol·mg^-1; p = 0.40), and EDL muscle (Cr: 14.9 ± 1.4 vs. Pl: 17.2 ± 1.5 nmol·mg^-1; p = 0.30). Additionally, Cr supplementation affected neither arterial blood pressure nor heart structure in SHR (p > 0.05).

Conclusions

Using a well-known experimental model of systemic arterial hypertension, this study did not confirm the possible therapeutic effects of Cr supplementation on oxidative stress and cardiovascular dysfunction associated with arterial hypertension.     

Application of direct fluid flow oscillations to improve mixing in microbioreactors

This article describes an active mixing method for a microbioreactor that was designed, simulated, tested, and successfully implemented. By applying a varying pressure to a microchannel looping tangentially into a cylindrical microreactor an oscillating fluid flow was shown to occur. Such an oscillating fluid flow improved mixing, both by diffusion and convection. The oscillating fluid flow has a large impact on the ratio between the diffusion domain and the convection domain. A good match was obtained between experimental mixing results, computational fluid dynamics simulation results and the results of a simplified mixing model thus demonstrating the potential of simulation on improving the design of microreactors. © 2009 American Institute of Chemical Engineers AIChE J, 2009