When radiochemistry meets radioecology (the marine environment)

After the first atomic bomb test in Alamogordo in July 1945, followed by the Hiroshima and Nagasaki bombs in August 1945, radioecology became recognized as a branch of ecology in response to the radioactive fallout associated with the subsequent proliferation of atmospheric nuclear weapons testing which continued throughout the Cold War. In parallel, environmental radiochemistry emerged in the 70s to understand the chemical behavior of possible nuclear contaminants of the environment. In this discussion we stress the need to crosslink radioecology and chemical speciation, where radiochemistry and radioecology should meet to go beyond the present state of the art. Accordingly, we are seeking a methodology that calls for several angles of investigation: speciation (chemistry), toxicology (physiology and biology), accumulation data (environmental studies), distribution (geochemistry).

Uranium contamination of bivalve Mytilus galloprovincialis, speciation and localization

Uranium is a natural radioelement (also a model for heavier actinides), but may be released through anthropogenic activities. In order to assess its environmental impact in a given ecosystem, such as the marine system, it is essential to understand its distribution and speciation, and also to quantify its bioaccumulation. Our objective was to improve our understanding of the transfer and accumulation of uranium in marine biota with mussels taken here as sentinel species because of their sedentary nature and ability to filter seawater. We report here on the investigation of uranium accumulation, speciation, and localization in Mytilus galloprovincialis using a combination of several analytical (Inductively Coupled Plasma Mass Spectrometry, ICP-MS), spectroscopic (X ray Absorption Spectroscopy, XAS, Time Resolved Laser Induced Fluorescence Spectroscopy, TRLIFS), and imaging (Transmission Electron Microscopy, TEM, μ-XAS, Secondary Ion Mass Spectrometry, SIMS) techniques. Two cohorts of mussels from the Toulon Naval Base and the Villefranche-sur-Mer location were studied. The measurement of uranium Concentration Factor (CF) values show a clear trend in the organs of M. galloprovincialis: hepatopancreas ≫ gill > body ≥ mantle > foot. Although CF values for the entire mussel are comparable for TNB and VFM, hepatopancreas values show a significant increase in those from Toulon versus Villefranche-sur-Mer. Two organs of interest were selected for further spectroscopic investigations: the byssus and the hepatopancreas. In both cases, U(VI) (uranyl) is accumulated in a diffuse pattern, most probably linked to protein complexing functions, with the absence of a condensed phase. While such speciation studies on marine organisms can be challenging, they are an essential step for deciphering the impact of metallic radionuclides on the marine biota in the case of accidental release. Following our assumptions on uranyl speciation in both byssus and hepatopancreas, further steps will include the inventory and identification of the proteins or metabolites involved.

Accumulation and Speciation of Cobalt in Paracentrotus lividus

Since the first human release of radionuclides on Earth at the end of the Second World War, impact assessments have been implemented. Radionuclides are now ubiquitous, and the impact of local accidental release on human activities, although of low probability, is of tremendous social and economic consequences. Although radionuclide inventories (at various scales) are essential as input data for impact assessment, crucial information on physicochemical speciation is lacking. Among the metallic radionuclides of interest, cobalt-60 is one of the most important activation products generated in the nuclear industry. In this work, a marine model ecosystem has been defined because seawater and more generally marine ecosystems are final receptacles of metal pollution. A multistep approach from quantitative uptake to understanding of the accumulation mechanism has been implemented with the sea urchin Paracentrotus lividus. In a well-controlled aquarium, the day-by-day uptake of cobalt and its quantification in different compartments of the sea urchin were monitored with various conditions of exposure by combining ICP-OES analysis and γ spectrometry. Cobalt is mainly distributed following the rating intestinal tract ≫ gonads > shell spines. Cobalt speciation in seawater and inside the gonads and the intestinal tract was determined using extended X-ray absorption fine structure (EXAFS). The cobalt inside the gonads and the intestinal tract is mainly complexed by the toposome, the main protein in the sea urchin P. lividus. Complexation with purified toposome was characterized and a complexation site combining EXAFS and AIMD (ab initio molecular dynamics) was proposed implying monodentate carboxylates.

6 months of radioxenon detection in western Europe with the SPALAX-New generation system - Part 2: Atmospheric transport modelling

Atmospheric transport modeling has been used to interpret the unprecedented number of multi-isotope detections of radioxenons observed during the six months of the qualification process by the Comprehensive Nuclear-Test-Ban Treaty Organization of the new SPALAX-NG system (Système de Prélèvement Automatique en Ligne avec l'Analyse du Xénon - Nouvelle Génération). Highest ¹³³Xe activity concentrations were found to be systematically associated with the concomitant measurement of several other radioxenons at the prevailing wind direction of north/northeast pointing to the Institute for Radio Elements (IRE), a medical isotope production facility located in Fleurus (Belgium). The lowest ¹³³Xe activity concentrations were not associated with a prevailing wind direction or other radioxenons, indicating the contribution of distant sources (global background). The IRE's average source terms for ^133mXe and to a lesser extent for ¹³³Xe (slightly overestimated by a factor of 1.7) showed good agreement with the literature values, while corrections by a factor of ~23 and ~53 were proposed for ^131mXe and ¹³⁵Xe since the initial values were underestimated. However, detections of ^131mXe alone and some low-activity concentrations of ¹³³Xe associated with only one of the other radioxenons could not be linked to the IRE releases. Analysis of these cases suggests the contribution of local source releases that have been difficult to identify to date. In addition to the global background, releases from such local sources, if not identified, could affect the analysis of the isotopic ratios measured following a nuclear test. The characterization of these local contributions is now possible owing to the capacity of the SPALAX-NG and other new generation measurements systems.

Uranium Uptake in Paracentrotus lividus Sea Urchin, Accumulation and Speciation

Uranium speciation and bioaccumulation were investigated in the sea urchin Paracentrotus lividus. Through accumulation experiments in a well-controlled aquarium followed by ICP-OES analysis, the quantification of uranium in the different compartments of the sea urchin was performed. Uranium is mainly distributed in the test (skeletal components), as it is the major constituent of the sea urchin, but in terms of quantity of uranium per gram of compartment, the following rating: intestinal tract > gonads ≫ test, was obtained. Combining both extended X-ray Absorption Spectroscopy and time-resolved laser-induced fluorescence spectroscopic analysis, it was possible to identify two different forms of uranium in the sea urchin, one in the test, as a carbonato-calcium complex, and the second one in the gonads and intestinal tract, as a protein complex. Toposome is a major calcium-binding transferrin-like protein contained within the sea urchin. EXAFS data fitting of both contaminated organs in vivo and the uranium-toposome complex from protein purified out of the gonads revealed that it is suspected to complex uranium in gonads and intestinal tract. This hypothesis is also supported by the results from two imaging techniques, i.e., Transmission Electron Microscopy and Scanning Transmission X-ray Microscopy. This thorough investigation of uranium uptake in sea urchin is one of the few attempts to assess the speciation in a living marine organism in vivo.

Focus on speciation assessment in marine radiochemistry using X-ray absorption spectroscopy

We review the state-of-the-art and recent advances in the determination of radionuclide speciation in seawater.

New insight into the ternary complexes of uranyl carbonate in seawater

Uranium is naturally present in seawater at trace levels and may in some cases be present at higher concentrations, due to anthropogenic nuclear activities. Understanding uranium speciation in seawater is thus essential for predicting and controlling its behavior in this specific environmental compartment and consequently, its possible impact on living organisms. The carbonato calcic complex Ca₂UO₂(CO₃)₃ was previously identified as the main uranium species in natural seawater, together with CaUO₂(CO₃)₃^2-. In this work, we further investigate the role of the alkaline earth cation in the structure of the ternary uranyl-carbonate complexes. For this purpose, artificial seawater, free of Mg²⁺ and Ca²⁺, using Sr²⁺ as a spectroscopic probe was prepared. Combining TRLIF and EXAFS spectroscopy, together with DFT and theoretical thermodynamic calculations, evidence for the presence of Sr alkaline earth counter ion in the complex structure can be asserted. Furthermore, data suggest that when Ca²⁺ is replaced by Sr²⁺, SrUO₂(CO₃)₃^2- is the main complex in solution and it occurs with the presence of at least one monodentate carbonate in the uranyl coordination sphere.

How Do Radionuclides Accumulate in Marine Organisms? A Case Study of Europium with Aplysina cavernicola

In the ocean, complex interactions between natural and anthropogenic radionuclides, seawater, and diverse marine biota provide a unique window through which to examine ecosystem and trophic transfer mechanisms in cases of accidental dissemination. The nature of interaction between radionuclides, the marine environment, and marine species is therefore essential for better understanding transfer mechanisms from the hydrosphere to the biosphere. Although data pertaining to the rate of global transfer are often available, little is known regarding the mechanism of environmental transport and uptake of heavy radionuclides by marine species. Among marine species, sponges are immobile active filter feeders and have been identified as hyperaccumulators of several heavy metals. We have selected the Mediterranean sponge Aplysina cavernicola as a model species for this study. Actinide elements are not the only source of radioactive release in cases of civilian nuclear events; however, their physicochemical transfer mechanisms to marine species remain largely unknown. We have targeted europium(III) as a representative of the trivalent actinides such as americium or curium. To unravel biological uptake mechanisms of europium in A. cavernicola, we have combined radiometric (γ) measurements with spectroscopic (time-resolved laser-induced fluorescence spectroscopy, TRLIFS, and X-ray absorption near-edge structure, XANES) and imaging (transmission electron microscopy, TEM, and scanning transmission X-ray microscopy, STXM) techniques. We have observed that the colloids of NaEu(CO₃)₂·nH₂O formed in seawater are taken up by A. cavernicola with no evidence that lethal dose has been reached in our working conditions. Spectroscopic results suggest that there is no change of speciation during uptake. Finally, TEM and STXM images recorded at different locations across a sponge cross section, together with differential cell separation, indicate the presence of europium particles (around 200 nm) mainly located in the skeleton and toward the outer surface of the sponge.

XAS and TRLIF spectroscopy of uranium and neptunium in seawater

Seawater contains radionuclides at environmental levels; some are naturally present and others come from anthropogenic nuclear activity. In this report, the molecular speciation in seawater of uranium(VI) and neptunium(V) at a concentration of 5 × 10(-5) M has been investigated for the first time using a combination of two spectroscopic techniques: Time-resolved laser-induced fluorescence (TRLIF) for U and extended X-ray absorption fine structure (EXAFS) for U and Np at the LIII edge. In parallel, the theoretical speciation of uranium and neptunium in seawater at the same concentration is also discussed and compared to spectroscopic data. The uranium complex was identified as the neutral carbonato calcic complex UO2(CO3)3Ca2, which has been previously described in other natural systems. In the case of neptunium, the complex identified is mainly a carbonato complex whose exact stoichiometry is more difficult to assess. The knowledge of the actinide molecular speciation and reactivity in seawater is of fundamental interest in the particular case of uranium recovery and more generally regarding the actinide life cycle within the biosphere in the case of accidental release. This is the first report of actinide direct speciation in seawater medium that can complement inventory data.

Simultaneous passenger lymphocyte syndrome and multiple alloimmunization against donor's blood group antigens after liver transplantation

BACKGROUND

If 'passenger lymphocyte syndrome' (PLS) is a well-recognized complication in ABO-mismatched solid organ transplantation, the coexistence of this reaction with recipient's alloimmunization against multiple antigens expressed on the residual red blood cells in the graft is less common and unpredictable.

METHODS

The receiver of an ABO minor-mismatch liver graft from a cadaveric donor developed haemolytic anaemia within 2 weeks after transplantation. The organ donor was of blood group O D+C+c+E+e+ K+k+ Le(a+b-) and the recipient, A1 D-C-c+E-e+ K-k+ Le(a-b-). The donor and recipient were both tested for irregular antibodies. Elution was performed on the recipient's red blood cells (RBCs).

RESULTS

None of the recipient and donor had irregular alloantibodies at the time of transplantation. On day 10, anti-A antibodies were detected in the recipient's serum and eluted from his RBCs. At the same time, the patient developed multiple alloantibodies: anti-D, anti-C, anti-E, anti-K and anti-Le(a) against the donor's erythrocyte antigens.

CONCLUSION

Although serological analysis and haemolytic parameters confirmed the diagnosis of PLS which required transfusion support, no sign of graft damage due to recipient's immune reaction was detected. This case illustrates the required follow-up of the recipient after transplantation.

Speciation of americium in seawater and accumulation in the marine sponge Aplysina cavernicola

The fate of radionuclides in the environment and especially in seawater is a cause of great concern for modern society and drives the need for experimental speciation studies.

[A KEL*02mod allele responsible for an apparent maternity exclusion]

The patient's rare KEL:1,-2 phenotype was highlighted in course of a routine preoperative erythrocyte typing. Unexpectedly, her two daughters presented a KEL:-1,2 phenotype what appeared first as an apparent maternity exclusion. Flow cytometry, genotyping and adsorption-elution analyses were then performed for those three patients. KEL genotyping showed that the patient's genotype was KEL*01/KEL*02 whereas that of her daughters was KEL*02/KEL*02. By using polyclonal anti-KEL2 reagent, weak amount of KEL2 was identified on the patient's erythrocytes, a result which was confirmed by both flow cytometry and adsorption-elution assays, suggesting that patient's phenotype was in fact KEL:1,2w. These results are in favour of a weak expressed KEL*02 allele (KEL*2mod) transmission coding for a KEL2 antigen detected in some technical conditions only. Those results allowed to explain the apparent maternity exclusion based on initial KEL phenotype. This study also seems to confirm the presence of a compensatory mechanism of the KELmod allele deficient expression in heterozygote patients. A KEL phenotype retrospective study of 80,000 subjects showed a local KEL:1,-2 frequency four times lower than that described in literature. Moreover, a significant number of those individuals would in reality be KEL:1,2w, what still would decrease the real frequency of the KEL:1,2 subjects.

[Hemoptysis in a young man smoking cannabis]

The respiratory toxicity of cannabis is well known today. Along with the classic cannabis 'joint', there are other ways of consuming it, which should be known. Smoking cannabis that has been cut with micro-particles of silicon dioxide may cause hemoptysis. We will describe here the case of a young 16-year-old man who was in the hospital because of hemoptic expectoration. The etiologic investigation was negative, in particular a thoracic scan and a bronchial fiberscope. Questioning the patient afterwards allowed us to discover the inhalation of cannabis 2 h before the hemoptysis, cannabis mixed with micro-particles of silicon dioxide. Stopping inhalation stopped the symptoms. Pediatricians should be familiarized with such practices. Silicon dioxide particles cause ENT problems or bronchial ones (coughing, spitting, hemoptysis, wheezing). Over the long term, the risk of silicosis cannot be excluded, although a longer and more complete exposure is necessary.

[Clinical case of the month. Mild hemolytic disease of the newborn due to an anti-Wr(a) antibody]

A Caucasian woman, with a A+ CCD.ee K neg erythrocyte phenotype and no history of blood transfusion, delivered a first child who developed mild anemia. The direct antiglobulin test performed on the newborn red blood cells belonging to the A+ CCD.ee K neg group, was strongly positive for IgG. During the pregnancy and after the delivery, the woman had a negative irregular antibody screening test, using standard red blood cells. However, at birth, using a collection of thawed red blood cells with rare phenotypes (private antigens), the lab showed an antibody anti-Wr(a) in the maternal serum. The activity of the maternal antibody, with a titer of 16, was completely inhibited by dithiothreitol, indicating the nature IgM of the circulating antibody. The presence of the antigen Wr(a) on the surface of the newborn and its biological father red blood cells was confirmed. The concentration of IgG anti-Wr(a) on baby erythrocytes was demonstrated by the presence of the antibody anti-Wr(a) in the eluate. This case illustrates the difficulties to detect antibodies against private antigens on baby erythrocytes, responsible of hemolytic diseases of newborn. Indeed, standard red blood cell panels used for irregular antibodies screening test do not express generally those private antigens.

[Understanding questions: a specific difficulty in children with pragmatic communication and language disorders]

INTRODUCTION

The question-answer schema is the basis for communicative interaction and is therefore a fundamental aim of the work carried out with children with severe communication and language impairment.

DEVELOPMENT

Answering questions requires basic skills that enable the listener to identify intonation and facial expression, as well as skills in interpreting intentions and in understanding linguistic content. Some questions can rest on contextual-social keys and others may be based on lexical or structural keys. Some questions, however, call for a more complex understanding, such as 'what' and 'who' questions. Here, we propose an analysis of the skills involved in understanding questions and the consequences on intervention strategies.

CONCLUSIONS

Intervention in understanding questions should combine different approaches (cognitive, social, linguistic) depending on the type of question, the specific difficulties the child has and the context.

Plutonium in the environment: key factors related to impact assessment in case of an accidental atmospheric release

This paper deals with plutonium and key factors related to impact assessment. It is based on recent work performed by CEA which summarize the main features of plutonium behaviour from sources inside installations to the environment and man, and to report current knowledge on the different parameters used in models for environmental and radiological impact assessment. These key factors are illustrated through a case study based on an accidental atmospheric release of Pu in a nuclear facility.

[Plasma calcium in haemodialysis patients: total calcium or ionized calcium? Should we systematically provide a value of total corrected calcium on our protocols?]

Ionized calcium is the only physiologically active form of calcium. Because of the variation of albumin, pH and haemoconcentration observed during haemodialysis session in patients with chronic renal failure, measure of total calcium does not reflect the real variation of ionized calcium. However, many formulae to correct total calcium by albumin have been proposed but none of them has been validated in dialysis patients. At present time, computing progress permit laboratory to systematically provide a value of corrected total calcium on protocols but is it really indicated? Our results showed that any of those formulae allows obtaining a value of total calcium that possesses a significant critical difference in relation to total calcium. Thus, correction formulae must be abandoned in aid of ionized calcium in haemodialysis patients.

Un nouveau cas de dysplasie hématodiaphysaire de Ghosal

Ghosal-type hematodiaphyseal dysplasia has been first described in 1986, as a steroid-dependent anemia with endosteal broadening of the long bone's diaphyses and metaphaphyses, which makes a distinction with the periosteal reaction in Camuratti-Engelmann's disease and with Caffey's disease. Extreme pallor is first noticed and leads to search for palpable thick long bones that are not always clinically obvious. The transmission of this rare entity seems to be autosomal recessive, with a common racial background from the Middle East and the Indian subcontinent. Anemia is considerably improved by steroids, which allow to avoid blood cells transfusions, but a minimum maintenance dose is necessary to keep the hemoglobin at a normal level probably during the whole life, involving iatrogen complications. The mechanism of anemia and the genetic cause of the disease are yet unknown.

[Speech therapy intervention in comprehension disorders]

INTRODUCTION

Most of the studies conducted on the subject of language pathologies have focused on the expressive aspect, but there is now generalised agreement on considering that most language disorders stem essentially from problems in the processes allowing input of verbal information provided by the environment.

DEVELOPMENT

We analyse the processes that take place in a child's mind when faced with verbal production and the communicative intentions of others, in an attempt to understand the nature of their difficulties.

CONCLUSIONS

The comprehension of oral language brings into play a series of extremely complex processes that combine different domains of higher mental functioning. Speech therapy intervention must ensure it analyses the true extent of the verbal comprehension of each child and attempt to achieve a representation of the levels of alteration involved in the faulty understanding.

[Intervention in children with pragmatic language and communication disorders]

AIMS

In this paper we analyse the educational and therapeutic needs of children who present pragmatic disorders in language and communication.

DEVELOPMENT

Pragmatic disorders in language and communication stand apart from the other disorders affecting the remaining aspects of language development. Their less specific nature goes beyond the purely linguistic domain and involves wide areas of the patient's affective and social development.

CONCLUSIONS

Not only is it necessary to adapt the general model of speech therapy intervention, but also to include it within a set of pedagogical (based on the framework of school itself) and psychological measures (in early care and family guidance services).

A comparative analysis of the modification of sexual desire of users of oral hormonal contraceptives and intrauterine contraceptive devices

OBJECTIVE

To compare the influence of oral hormonal contraceptives (OCs) and the use of intrauterine contraceptive devices (IUDs) on the modification of sexual desire.

MATERIALS AND METHODS

A prospective observational study of 1073 women using OCs or an IUD at the Family Planning Center 'Marina Alta' in Alicante, Spain. In order to evaluate the relative risk regarding the decrease in libido attributed to each contraceptive method, a logistic regression analysis was undertaken which considered the factors of age adjustment, level of studies, family planning information, relationship with partner, age when sexual relationships were initiated, parity, contraceptive method previously used and the duration of use of the contraceptive method.

RESULTS

No differences in the decrease of sexual desire were observed between the use of the OC and IUD (odds ratio (OR) 1.32; 95% confidence interval (CI) 0.70-2.49), yet differences were noted, however, in relation to age (OR 1.05; 95% CI 1.01-1.10). Although these differences were not statistically significant, a high level of awareness regarding family planning was shown to increase sexual desire when compared to a lower level of information on this subject (OR 0.64; 95% CI 0.41-1.01). Sexual desire was seen to decrease if the quality of the relationship with the partner was average (OR 2.24; 95% CI 1.36-3.69) or poor (OR 4.69; 95% CI 1.93-11.4). Nulliparous women showed a greater decrease in sexual desire in relation to women who had already given birth (OR 1.57; 95% CI 1.00-2.47). Sexual desire was greater if the contraceptive method had already been in use for 6-12 months (OR 0.41; 95% CI 0.17-0.98).

CONCLUSIONS

Sexual desire does not vary in relation to the use of OCs or IUDs, yet it does decrease with age, in nulliparous women and in those with an average or poor relationship with their partner. Furthermore, sexual desire shows an increase between the first 6 and 12 months of contraceptive treatment.

Response of the flexion-relaxation phenomenon relative to the lumbar motion to load and speed

STUDY DESIGN

Nonrandomized control trial.

OBJECTIVE

To determine if the variations of speed and loading conditions during trunk flexion-extension could influence the times of occurrence and disappearance of the electrical silence of the erector spinae muscles, the degrees of lumbar flexion at those instants, and the relative lumbar motion time.

SUMMARY OF BACKGROUND DATA

It has been suggested that varying either the speed of movement or the load on the trunk during trunk flexion-extension movements may influence the flexion-relaxation phenomenon or the kinesiologic data. However, no study dealt with the simultaneous effect of the speed of movement on the spine rhythm and on the occurrence of the electrical silence of the erector spinae.

METHODS

A total of 22 pain-free volunteers performed a series of trunk flexion-extension movements varying the speed and load. The motion of the lumbar spine ( degrees ) and the integrated electromyography (microV) of erector spinae muscles were simultaneously recorded. Two measures were calculated: the percentage of the maximum lumbar spine flexion at the instants when changes of electrical activity represented the beginning and end of the electrical silence and the relative lumbar spine motion time during trunk flexion and extension movements.

RESULTS

The increase in speed of movement significantly increased the relative lumbar flexion time and significantly reduced the relative lumbar extension time (t = 2.49 and t = 2.25, P < 0.05); furthermore, it significantly delayed the appearance of the electrical silence in the range of flexion (t = 3.52, P < 0.01). There was no significant effect from a change in load.

CONCLUSIONS

The relative spine motion time differed depending on the direction of movement, being longer during trunk flexion and shorter during extension. The increase in speed of movement produced greater differences in the relative time between trunk flexion and extension; furthermore, it delayed the appearance of the electrical silence of the erector spinae muscles in the range of flexion.

Synthesis, structure, and magnetic properties of three new one-dimensional nickel(II) complexes: new magnetic model for the first one-dimensional S = 1 complex with alternating ferro-ferromagnetic coupling

Three new one-dimensional nickel(II) complexes with the formulas trans-[Ni(N-Eten)2(mu1.3-N3)]n(ClO4)n (1), trans-[Ni(N-Eten)2(mu1.3-N3)]n(PF6)n (2), and cis-[Ni(N-Eten)(mu1.1-N3)2]n (3) (N-Eten = N-Ethylethylenediamine) were synthesized and characterized. Complex 1 has the P2(1)/c space group and consists of a structurally and magnetically alternating one-dimensional antiferromagnetic system with end-to-end azido bridges. Compound 2 has the P1 space group and has alternate units in its structure but consists of a magnetically uniform one-dimensional antiferromagnetic system with end-to-end azido bridges. Complex 3 has the I2/a space group and may be described as a structurally and magnetically alternating one-dimensional ferromagnetic system with double azido bridged ligands in an end-on coordination mode. The chi(M)T versus T plots for compound 3 suggest an intramolecular ferromagnetic interaction between adjacent NiII ions and metamagnetism at low temperature (below 10 K). The magnetization measurements versus applied field confirm this metamagnetic ordering. In order to describe the magnetic data of this compound we developed a general formula for the magnetic susceptibility of the isotropic ferro-ferromagnetic S = 1 Heisenberg chain in terms of the alternation parameter alpha (= J2/J1); this assumed a variation of chi(M)T versus the length N.

Synthesis, structure, and magnetic properties of two new ferromagnetic/antiferromagnetic one-dimensional nickel(II) complexes. Magnetostructural correlations

Two new one-dimensional nickel(II) complexes were synthesized and characterized: [Ni(N,N-dimethylethylenediamine)(N3)2] (1) and [Ni(2-aminoethylpyridine)(N3)2] (2). The crystal structures of 1 and 2 were solved. Complex 1 crystallizes in the monoclinic system, space group P2(1)/n with a = 10.569(2) A, b = 7.331(4) A, c = 12.9072(8) A, beta = 111.324(10) degrees, and Z = 4. Complex 2 crystallizes in the monoclinic system, space group P2(1)/c with a = 12.299(5) A, b = 14.307(2) A, c = 12.604(3), beta = 106.72(2) degrees, and Z = 4. The two complexes are similar and may be described as one-dimensional systems with double-azido-bridged ligands in end-to-end and end-on coordination alternatively. The end-on moiety is almost identical for 1 and 2, but the end-to-end moiety is different in each structure: for 1 this part is almost planar but for 2 is nonplanar. In both cases the Ni atoms are situated in similar distorted octahedral environments. The magnetic properties of the two compounds were studied by susceptibility measurements vs temperature. The chi M vs T plots for 1 and 2 show a global antiferromagnetic behavior with a maximum near room temperature for 1 and at very low temperature for 2. J values for 1 and 2 were deduced from the spin Hamiltonian -sigma(J1SiSi+1 + J2Si+1Si+2). The computational method was based on the numerical solution for finite systems of increasing size. J values for 1 were J1 = -187 cm-1 and J2 = +77 cm-1 and for 2 J1 = -28 cm-1 and J2 = +73 cm-1. The positive values correspond to end-on azido ligands and the negative values to end-to-end azido ligands. Since the geometries of the [Ni(N3)]2 moieties involving the end-on azido ligands are almost the same in the two structures, the ferromagnetic coupling is nearly identical in the two compounds, while the significantly different antiferromagnetic couplings reflect the near planarity of the end-to-end Ni2(N3)2 fragment in 1 and its twisted geometry in 2.

A software tool to acquire, synchronise and playback multimedia data: an application in kinesiology

Assessing the physical condition of the human body frequently requires evaluating different tests performed by different devices. This information has to be analysed simultaneously to derive conclusions, and so a temporal relationship must be established between the data sources. In this paper, synchronisation of the sources of information is achieved by synchronising the clocks of computers connected in a Local Area Network. A clock synchronisation protocol is used and a global time is stamped in each information data flow. During analysis, the time-stamp is used to playback the data in a synchronised way. The proposed system is valid for any medical application in which data synchronisation is needed. However, it has initially been used in a distributed medical environment for analysing electrical muscular activity and lumbar movement. The dual aim is to detect injuries and plan training sessions for athletes. It was specifically used to analyse data generated by: electromyographs; lumbar equipment; and images generated by video cameras. The simple operation of the application and the precision of the synchronisation protocol enabled several interesting medical conclusions to be made.

A Metamagnetic Two-Dimensional Molecular Material with Nickel(II) and Azide

Bridging azido ligands transmit both ferro- and antiferromagnetic interactions. The sheetlike structured complex [Ni(µ-N(3))(2)(N,N-Et(2)-N'-Me-en)](n) (see picture) exhibits a range of magnetic behaviors at low temperature. Short-range ferromagnetic and three-dimensional antiferromagnetic ordering compete, giving metamagnetic behaviors. N,N-Et(2)-N'-Me-en=N,N-diethyl-N'-methylethylenediamine.

Muscle activity in upper and lower rectus abdominus during abdominal exercises

OBJECTIVE

To compare the intensity of the upper versus lower rectus abdominis (RA) muscle activity provoked by each of two different abdominal exercises and to contrast the intensity of contraction elicited by two different abdominal exercises on each RA muscle portion.

DESIGN

Nonrandomized control trial.

SETTING

Kinesiology laboratory in a university medicine faculty.

PARTICIPANTS

Convenience sample of 33 healthy volunteers. Subjects who had practiced endurance or strength training activities (1.5 hours 3 days a week for 3 years) and those who had not accomplished that criterion comprised a high and a low physical activity group, respectively. Each of these two groups was divided by the ability to perform the exercises into two subgroups: correct and incorrect performers (cp, ic).

MAIN OUTCOME MEASURE

Average surface iEMG was compared between upper and lower RA and on each muscle portion performing curl-up (CU) and posterior pelvic tilt (PT) exercises. The coefficient of variation, a two-way analysis of variance, and the t test were calculated.

RESULTS

The upper RA showed significantly greater activity during performance of CU exercise by the cp subgroups of both high (t = 2.14302, 95%) and low (t = 2.35875, 95%) activity groups. Only the cp subgroup of the high activity group showed that PT was significantly more strenuous than CU exercise on lower RA (t = -2.06467, 95%).

CONCLUSIONS

Among correct performers, CU produces greater activity on upper RA. For persons who have a high level of activity, PT is more strenuous than CU on lower RA. Among incorrect performers, either exercise indistinctly activates the muscle portions.

[Negativity of the exercise thallium test despite tight stenosis of the common trunk of the left coronary artery]

The authors report a case of severe angina linked to subocclusive ostial stenosis of the common trunk of the left coronary, characterised by the contrast between a very positive stress test on the basis of clinical and electrocardiographic parameters and a negative Thallium stress test. The occasion is taken to review the sensitivity of Thallium stress testing in lesions of the common trunk.

Information-processing differences and laterality of students from different colleges and disciplines

1023 college students were assessed for hemispheric brain dominance using the paper-and-pencil test, the Human Information Processing Survey. Analysis of scores of students majoring in Advertising, Interior Design, Music, Journalism, Art, Oral Communication, and Architecture suggested a preference for right-brain hemispheric processing, while scores of students majoring in Accounting, Management, Finance, Computer Science, Mathematics, Nursing, Funeral Service, Criminal Justice, and Elementary Education suggested a preference for left-hemispheric strategies for processing information. The differential effects of hemispheric processing in an educational system emphasizing the left-hemispheric activities of structured logic and sequential processing suggests repression of the intellectual development of those students who may be genetically favorable to right-hemispheric processing.