Hydrothermal conversion of carbon dioxide into formate with the aid of zerovalent iron: the potential of a two-step approach.

Our research focuses on the hydrothermal conversion of carbon dioxide into formate with the aid of zerovalent iron. Conventionally, a one-step approach is applied wherein both (I) the production of hydrogen gas, through the oxidation of zerovalent iron in an aqueous medium and (II) the conversion of carbon dioxide with this hydrogen gas into formate/formic acid, are performed under the same reaction conditions at a temperature of approximately 300 °C. Until now, the yields of formate/formic acid mentioned in the literature are, in the absence of a catalytic substance, low (13.5%). Recently, we developed a hydrothermal hydrogen gas production method based on the oxidation of zerovalent iron and performed under mild conditions (temperature of 160 °C). This synthesis method produces hydrogen gas with a high purity (>99 mol%) and a significant yield (approximately 80 mol%). These experimental results suggested that the optimal hydrothermal reaction conditions for the production of hydrogen gas and the conversion of carbon dioxide, are strongly different in case of applying zerovalent iron as the reducing agent. Therefore, this paper studies the potential of a two-step approach to enhance the carbon conversion yields. The first step is the production of hydrogen gas via the developed method at 160 °C. The second step is the conversion of carbon dioxide at higher temperatures (250-350 °C). This study reveals that the solubility of hydrogen gas into the aqueous solution is a key parameter in order to achieve a high amount of carbon conversion. Therefore, a high temperature, the degree of filling and the initial hydrogen gas amount are necessary to successfully perform the carbon dioxide conversion step with high carbon conversion yields. Applying these insights have led to the experimental observation that via a two-step approach the conversion of potassium hydrogen carbonate into potassium formate can be successfully performed with higher carbon conversion yields, up to 77.9 wt%, and a selectivity of at least 81% when applying a reaction temperature of 280 °C for 24 hours, a degree of filling with water of 50 vol% and an initial amount of hydrogen gas of 100 mmol.

Altered structural networks and executive deficits in traumatic brain injury patients.

Recent research on traumatic brain injury (TBI) has shown that impairments in cognitive and executive control functions are accompanied by a disrupted neural connectivity characterized by white matter damage. We constructed binary and weighted brain structural networks in 21 patients with chronic TBI and 17 healthy young adults utilizing diffusion tensor tractography and calculated topological properties of the networks using a graph theoretical method. Executive function was assessed with the local global task and the trail making task, requiring inhibition, updating, and switching. The results revealed that TBI patients were less successful than controls on the executive tasks, as shown by the higher reaction times, higher switch costs, and lower accuracy rates. Moreover, both TBI patients and controls exhibited a small world topology in their white matter networks. More importantly, the TBI patients demonstrated increased shortest path length and decreased global efficiency of the structural network. These findings suggest that TBI patients have a weaker globally integrated structural brain network, resulting in a limited capacity to integrate information across brain regions. Furthermore, we showed that the white matter networks of both groups contained highly connected hub regions that were predominately located in the parietal cortex, frontal cortex, and basal ganglia. Finally, we showed significant correlations between switching performance and network property metrics within the TBI group. Specifically, lower scores on the switching tasks corresponded to a lower global efficiency. We conclude that analyzing the structural brain network connectivity provides new insights into understanding cognitive control changes following brain injury.

Evaluation of quality of life in people with aphasia using a Dutch version of the SAQOL-39.

PURPOSE: To examine the quality of life (QoL) of people with aphasia and to study the influence of variables such as age, time post onset and (degree of) social support on the QoL of aphasic persons. METHOD: We compared the scores of an aphasic population (N = 43) with those of a healthy control group (N = 43) and of a group of patients with brain lesions without neurogenic communication disorders (N = 43) on a Dutch version of the Stroke and Aphasia Quality of Life-scale (SAQoL-39) and on a social support questionnaire. In half of the aphasic group, the SAQoL-39 was re-administered 8 months after the first testing. RESULTS: People with aphasia obtained significantly lower scores for QoL measures compared with both other groups. Especially, communicative and psychosocial factors seem to influence these results. Older people with aphasia scored lower than younger persons and women tend to evaluate their QoL somewhat more negatively than men. Persons who had aphasia for more than 6 months tended to have higher QoL-scores compared with those who had become aphasic more recently. After 8 months, the retested group scored significantly higher on communication and on psychosocial functioning than on first testing. CONCLUSIONS: Gathering information on QoL after suffering from stroke and from aphasia can lead to a better understanding of the problems involved. The clinical use of instruments such as the SAQoL-39 can probably contribute to a more patient oriented rehabilitation, whereby the focus not only lie in improving linguistic skills but also on reducing the impairments and the handicaps that accompany aphasia and thus on increasing QoL.

Protective effect of hop beta-acids on microbial degradation of thick juice during storage.

AIMS: This study assessed the value of a commercial alkaline solution of hop beta-acids (HBA) for prevention of microbial degradation of thick juice, a concentrated intermediate product in the production of beet sugar. METHODS AND RESULTS: The antimicrobial effect of different concentrations of HBA against microbial degradation of thick juice was tested in a pilot-scale storage experiment. Chemical, biochemical and microbial parameters were monitored during thick juice storage. Thick juice degradation, indicated as a decrease in pH, was generally accompanied by an increase in the count of fastidious bacteria (FB) on Columbia Agar with Sheep Blood (CAwSB), which were mainly identified as Tetragenococcus halophilus. Addition of HBA delayed juice acidification and the development of FB in a concentration-dependent manner. The susceptibility of FB to HBA was determined by plating degraded thick juice (FB > 10(5) CFU ml(-1) on CAwSB plates with different concentrations of HBA (0-160 ppm). None of the HBA concentrations tested reduced the number of FB colonies formed, but increasing HBA concentrations extended the lag time of colony formation. CONCLUSIONS: HBA produce no measurable bactericidal effect, but retard the development of FB in thick juice. Moreover, HBA do not prevent the thick juice from deteriorating, but significantly delay its degradation. SIGNIFICANCE AND IMPACT OF THE STUDY: These results indicate that adding a commercially available HBA formulation can prolong the storage life of thick juice in the sugar industry, although degradation cannot be eliminated. Future research will focus on the detailed characterization of FB consistently isolated from degraded thick juice and on determining their role in thick juice degradation.

[Analytic inpatient treatment of malignant narcissism. A case study]. / Analytisch-residentiële behandeling van maligne narcisme.

It is extremely doubtful whether a patient diagnosed with malignant narcissism will respond positively to analytic therapy, particularly group therapy. The prospects for recovery are not favourable because a patient with malignant narcissism has a tendency to destroy everything that is good, including the therapeutic relationship, and this destructiveness can seriously undermine the treatment of other patients. Nevertheless, in this article a case is presented that illustrates that long-term analytic in-patient treatment can be successful. The theoretical background to the diagnosis is outlined so that readers will be able to understand the nature of the treatment.

[Persistant complaints after endodontic treatment]. / Persisterende klachten na een endodontische behandeling.

A 51-year-old man was referred to an oral and maxillofacial surgeon because of persistent complaints after endodontic treatment of tooth 22. Apical endodontic surgery was performed and periapical tissue was examined histopathologically, showing an osteosarcoma. In retrospect, signs of malignancy were already present on the radiograph taken prior to the endodontic treatment.

Neuropsychological deficits in patients with an anterior communicating artery syndrome: a multiple case study.

The neuropsychological performance of five patients with an anterior communicating artery (ACoA) syndrome (amnesia, confabulation and personality changes) was studied. Neuroimaging techniques revealed a basal forebrain and frontal lobe pathology in all patients. The limbic system appeared intact. There was no evidence for an intellectual deterioration relative to the estimated premorbid IQ in four patients. Regarding attention, all patients showed significant deficits. Visuospatial disabilities could not be observed. On tests of executive functioning, all patients did exhibit severe problems. Every patient displayed a profound amnesic syndrome. A retrograde amnesia could be documented and was characterised by a temporal gradient. Short-term memory appeared normal. Concerning long-term memory, all patients scored out of the normal range on total immediate recall tasks. Four patients showed a normal recognition performance but produced a large number of false alarms. Despite a normal recognition performance, they were impaired in delayed recall tasks. However, one patient showed a full-blown amnesic syndrome, because his delayed recall and recognition of learned items were both depressed. Our results with regard to long-term memory functioning support the hypotheses which assume (1) the existence of recognition superiority and pathological false recognition, and (2) basal forebrain amnesia in ACoA patients.

Case report of a patient with complex partial frontal lobe seizures as a complication of bifrontal lobotomy.

This case report describes an 85 year-old woman who underwent a bilateral frontal lobotomy for presumed schizophrenia 50 years ago. The patient presented with sudden alterations of consciousness accompanied by motionless staring and speech and movement arrest. After 5 to 10 seconds, contact recovered briskly. As there was electrophysiological evidence for a frontal epileptic focus, these fits were classified as complex partial frontal lobe seizures with impairment of consciousness at onset. An aetiological link with the bifrontal lobotomy is probable. At the occasion of this case report, complications of frontal lobotomy are reviewed.

Drug-induced spongiform leucoencephalopathy, a case report with review of the literature.

A nineteen year-old girl developed rhabdomyolysis and central pyrexia after the ingestion of multiple drugs: amphetamines, benzodiazepines, methadone, ethanol, and cocaine. On admission, the patient was deeply comatose and during the hospitalisation asymmetrical spastic quadriparesis was noted. Brain biopsy was diagnostic of spongiform leucoencephalopathy. A review of the literature concerning drug-induced spongiform encephalopathy revealed a large amount of heroin-induced cases. The role of cocaine, however, is less well described. After prolonged hospitalisation, our patient improved clinically and radiologically and could be transferred to a rehabilitation center.

Personality, emotions and the temporolimbic system: a neuropsychological approach.

Over the past decade a view has emerged that there is both a lateralization of control of certain emotional processes, the right hemisphere being dominant, and a localization of control to the limbic system, the frontal and temporal lobes. Many changes in personality, social behaviour and emotions can be seen in patients with temporal lobe lesions. Examples of these changes are a deficit in the interpretation of emotional components of language, a reduction in the frequency and intensity of facial expressions, an impairment of the judgement of mood, facial expressions and emotional situations. Buried within the depths of the brain is the limbic system which represents the most primitive features of our emotional system and contains several nuclei. Of special interest are the hypothalamus, amygdala, hippocampus and septal nuclei, the social-emotional functions they mediate and the neural circuit that supports their activity.

Cloning, sequencing, and phenotypic analysis of laf1, encoding the flagellin of the lateral flagella of Azospirillum brasilense Sp7.

Azospirillum brasilense can display a single polar flagellum and several lateral flagella. The A. brasilense Sp7 gene laf1, encoding the flagellin of the lateral flagella, was isolated and sequenced. The derived protein sequence is extensively similar to those of the flagellins of Rhizobium meliloti, Agrobacterium tumefaciens, Bartonella bacilliformis, and Caulobacter crescentus. An amino acid alignment shows that the flagellins of these bacteria are clustered and are clearly different from other known flagellins. A laf1 mutant, FAJ0201, was constructed by replacing an internal part of the laf1 gene by a kanamycin resistance-encoding gene cassette. The mutant is devoid of lateral flagella but still forms the polar flagellum. This phenotype is further characterized by the abolishment of the capacities to swarm on a semisolid surface and to spread from a stab inoculation in a semisolid medium. FAJ0201 shows a normal wheat root colonization pattern in the initial stage of plant root interaction.

Effects of type of exercise on depression in recovering substance abusers.

This experiment investigated the effects of three types of structured exercise (aerobics, bodybuilding, and circuit training) on depressive symptoms of 45 clients undergoing a 4-wk., inpatient rehabilitation program for substance abuse. Pre- and posttest measures included the Center of Epidemiological Studies--Depression, resting pulse rate, blood pressure, maximum strength on incline bench press, and estimates of aerobic fitness and body fat. The bodybuilding program produced a significant decrease in depressive symptoms. Physiological and psychological explanations are discussed.

Identification and mapping of loci involved in motility, adsorption to wheat roots, colony morphology, and growth in minimal medium on the Azospirillum brasilense Sp7 90-MDa plasmid.

We have constructed a cosmid library of the Azospirillum brasilense Sp7 90-MDa plasmid (p90) and established the EcoRI restriction map of this plasmid. The central regions of cloned p90 DNA fragments from several recombinant cosmids were deleted by restriction endonuclease digestion and replaced by a DNA cassette encoding kanamycin resistance. Using these in vitro constructed deletions for marker exchange in Sp7, we made six different p90 deletion derivatives spanning all together 50% of the total length of p90. Comparison of the deletion derivatives with Sp7 for several properties revealed p90 loci involved in colony morphology, growth on minimal medium, motility, and adsorption to wheat roots. In analogy with the rhizobial symbiotic plasmids (pSym), we propose to denote the p90 plasmid as a rhizocoenotic plasmid (pRhico), carrying several genes involved in the A. brasilense-plant root interaction.

Phosphonylation of purified human, canine and porcine cholinesterase by soman. Stereoselective aspects.

Cholinesterases (EC 3.1.1.8, acylcholine acylhydrolase) from the sera of man, dog and pig were purified 400-600-fold using a combination of ion-exchange and affinity chromatography. In a first approach, phosphonylation by soman was studied by using the half-resolved epimers C(+)P(+/-)-soman and C(-)P(+/-)-soman. The degradation of soman at the nanomolar level was followed in time by determining the remaining soman by capillary gas chromatography with NP detection. In the three sera investigated the P-(-)-epimer phosphonylates at a higher rate than its corresponding P(+)-counterpart and the stereoselectivity is greater for the C(+)-epimers than for the C(-)-epimers. Individual soman isomers were isolated from C(+)- and C(-)-epimers and quantified by gas chromatography. Second-order rate constants were determined for the phosphonylation of purified cholinesterase by isolated soman isomers. The C(+)P(-)-isomer has the highest phosphonylation rate for the three species; the other toxic isomer, C(-)P(-), has a five to ten-fold lower rate. The overall stereoselectivity is more marked in human cholinesterase than in canine. Porcine serum cholinesterase is phosphonylated by the P(-)-isomers at a slightly higher rate than the human enzyme.

Construction of an Azospirillum brasilense Sp7 recA mutant.

Cosmid clones encoding the recA gene of Azospirillum brasilense were isolated by intergeneric complementation of an Escherichia coli recA mutant. Site-directed Tn5 mutagenesis and subcloning of one complementing cosmid clone allowed us to localize the A. brasilense recA gene on a 1.2 kb DNA fragment. One Tn5 insertion that inactivates the cloned recA gene was crossed into the chromosome of A. brasilense by marker exchange. The resulting A. brasilense recA mutant showed increased sensitivity to the DNA methylating agent methyl methanesulfonate and to ultraviolet light and had at least one hundredfold reduced recombinational activity compared to the parent strain.

Cloning and expression in Escherichia coli of the Azospirillum brasilense Sp7 gene encoding ampicillin resistance.

The Azospirillum brasilense ATCC 29145 gene coding for beta-lactamase was cloned in Escherichia coli. The gene was expressed in E. coli from its own promoter as a 30-kilodalton protein, conferring resistance to high levels of beta-lactam antibiotics. The DNA sequence containing the beta-lactamase gene was found to be highly amplified in the Azospirillum genome, scattered in the chromosomal as well as in the plasmidic DNA.

Plasmid localization and mapping of two Azospirillum brasilense loci that affect exopolysaccharide synthesis.

Two Azospirillum brasilense loci that correct Rhizobium meliloti exoB and exoC mutants for exopolysaccharide (EPS) synthesis have been identified previously (K. W. Michiels, J. Vanderleyden, A. P. Van Gool, E. R. Signer, J. Bacteriol., 1988b). A. brasilense exo mutants produce EPS of lower molecular weight than the wild type strain. Here, we show by hybridization that these exo loci are located on a 90-MDa plasmid in A. brasilense Sp7. In four other Azospirillum strains but not in A. lipoferum SpBr17, the loci are likewise located on a plasmid of approximately the same size. Transposon Tn5 insertions in these loci were isolated and mapped on the cloned DNA by restriction analysis. Hybridization of restriction digests of purified 90-MDa plasmid DNA with probes containing the exo loci confirmed their plasmid location. This is the first report on plasmid localization of genes in Azospirillum.

Isolation and characterization of Azospirillum brasilense loci that correct Rhizobium meliloti exoB and exoC mutations.

The occurrence in Azospirillum brasilense of genes that code for exopolysaccharide (EPS) synthesis was investigated through complementation studies of Rhizobium meliloti Exo- mutants. These mutants are deficient in the synthesis of the major acidic EPS of Rhizobium species and form empty, non-nitrogen-fixing root nodules on alfalfa (J. A. Leigh, E. R. Signer, and G. C. Walker, Proc. Natl. Acad. Sci. USA 82:6231-6235, 1985). We demonstrated that the exoC mutation of R. meliloti could be corrected for EPS production by several cosmid clones of a clone bank of A. brasilense ATCC 29145. However, the EPS produced differed in structure from the wild-type R. meliloti EPS, and the symbiotic deficiency of the exoC mutation was not reversed by any of these cosmid clones. The exoB mutation could be corrected not only for EPS production but also for the ability to form nitrogen-fixing nodules on alfalfa by one particular cosmid clone of A. brasilense. Tn5 insertions in the cloned DNA were isolated and used to construct Azospirillum mutants with mutations in the corresponding loci by marker exchange. It was found that these mutants failed to produce the wild-type high-molecular-weight EPS, but instead produced EPSs of lower molecular weight.

Transposon Mutagenesis of Azospirillum brasilense and Azospirillum lipoferum: Physical Analysis of Tn5 and Tn5-Mob Insertion Mutants.

Tn5-induced insertion mutants were generated in Azospirillum brasilense Sp7 and A. lipoferum SpBr17 by mating with Escherichia coli strains carrying suicide plasmid vectors. The sources of Tn5 were the suicide plasmids pGS9 and pSUP2021. Kanamycin-resistant Azospirillum colonies appeared from crosses with E. coli at maximum frequencies of 10 per recipient cell. Transposon Tn5 also conferred streptomycin resistance on Azospirillum colonies as was observed earlier for Rhizobium sp. Eight Tn5-induced Km SmA. brasilense Sp7 mutants with reduced nitrogen-fixing capacity were isolated. The potential use of Tn5-Mob for labeling and mobilization of Azospirillum-indigenous plasmids was demonstrated by isolating Tn5-Mob insertions in the megaplasmids of A. brasilense Sp7.

Nucleotide sequence of an insertion sequence (IS) element identified in the T-DNA region of a spontaneous variant of the Ti-plasmid pTiT37.

We have identified and determined the nucleotide sequence of an IS element (IS136) of Agrobacterium tumefaciens. This is the first IS element isolated and sequenced from a nopaline type Ti-plasmid. Our IS element has 32/30 bp inverted repeats with 6 mismatches, is 1,313 bp long and generates 9 bp direct repeats upon integration. IS136 has 3 main open reading frames (ORF's). Only ORF1 (159 codons) is preceded by sequences that are proposed to serve functional roles in transcriptional and translational initiation. No DNA sequence homology was found between IS136 and IS66, an IS element isolated from an octopine type Ti-plasmid.