Physical characteristics of the back are not predictive of low back pain in healthy workers: A prospective study

Background. In the working population, back disorders are an important reason for sick leave and permanent work inability. In the context of fitting the job to the worker, one of the primary tasks of the occupational health physician is to evaluate the balance between work-related and individual variables. Since this evaluation of work capacity often consists of a physical examination of the back, the objective of this study was to investigate whether a physical examination of the low back, which is routinely performed in occupational medicine, predicts the development of low back pain (LBP). Methods. This study is part of the Belgian Low Back Cohort (BelCoBack) Study, a prospective study to identify risk factors for the development of low back disorders in occupational settings. The study population for this paper were 692 young healthcare or distribution workers (mean age of 26 years) with no or limited back antecedents in the year before inclusion. At baseline, these workers underwent a standardised physical examination of the low back. One year later, they completed a questionnaire on the occurrence of LBP and some of its characteristics. To study the respective role of predictors at baseline on the occurrence of LBP, we opted for Cox regression with a constant risk period. Analyses were performed separately for workers without any back antecedents in the year before inclusion ('asymptomatic' workers) and for workers with limited back antecedents in the year before inclusion ('mildly symptomatic' workers). Results. In the group of 'asymptomatic' workers, obese workers showed a more than twofold-increased risk on the development of LBP as compared to non-obese colleagues (RR 2.57, 95%CI: 1.09 - 6.09). In the group of 'mildly symptomatic' workers, the self-reports of pain before the examination turned out to be most predictive (RR 3.89, 95%CI: 1.20 - 12.64). Conclusion. This study showed that, in a population of young workers wh no or limited antecedents of LBP at baseline, physical examinations, as routinely assessed in occupational medicine, are not useful to predict workers at risk for the development of back disorders one year later

Predictieve risicofactoren voor lage rugpijn bij jonge werknemers : de BELCOBACK-studie

peer reviewe

Risk factors for first-ever low back pain among workers in their first employment

Background Low back pain has been estimated to be the most costly ailment of people of working age. Both work characteristics and individual factors have been identified as risk factors. The first interaction between work characteristics and individual factors occurs when workers start in their first job. Aims To investigate work-related risk factors for first-ever low back pain in young workers in their first employment. Methods A cross-sectional analysis was performed on 278 young workers in their first employment and without a history of low back pain prior to working. Work-related physical factors, psychosocial work characteristics, individual variables and first-ever low back pain were queried by means of a questionnaire. Results About half of the workers who developed low back pain after job start did so in the first year of employment. An increased risk was observed for (i) long periods of seated work [relative risk (RR) = 3.2, 95% confidence interval (CI) = 1.6-6.4]; (ii) more than 12 flexion or rotation movements of the trunk per hour (RR = 3.0, 95% CI = 1.4-6.4); and (iii) more than 3 years seniority in a job involving lifting more than 25 kg at least once an hour (RR = 3.7, 95% CI = 1.4-9.4). As to psychosocial work characteristics, first-ever low back pain was associated with a combination of low psychological job demands and low supervisor support. Conclusion Work-related physical factors and psychosocial work characteristics should be considered as risk factors for first-ever low back pain. First-ever episodes of low back pain are common in the first year of employment. This may reflect a lack of work experience or training

BelCoBack. Une étude prospective sur les facteurs étiologiques et pronostiques des maux de dos liés à la profession

peer reviewe

Investigation of the Nozzle Diameter as a Control Parameter of the Properties of Melt-Spun Sb2−x Bi x Te3.

International audienceThree kinds of Sb1.6Bi0.4Te3.1 samples were prepared by the melt-spinning technique using quartz tubes with different nozzle’s diameters (1.0, 0.7 and 0.5 mm) to study the sensitivity of the thermoelectric properties to the variations of this parameter. The melt-spun ribbons were densified by spark plasma sintering (SPS). The melt-spun samples were characterized by powder x-ray diffraction and scanning electron microscopy. The dimensionless figures of merit (ZT) were calculated from the data obtained by measuring the Seebeck coefficient, electrical resistivity and thermal conductivity in the direction perpendicular to the uniaxial pressing direction of SPS. All ZT values for this set of samples were close to 1.0 around 380 K. The highest ZT value was obtained for the sample prepared using the largest nozzle diameter of 1.0 mm. Despite some variations in the carrier concentrations of the samples being observed, these results indicate a weak sensitivity of the melt-spun Sb1.6Bi0.4Te3.1 samples to the nozzle’s diameter during the melt-spinning process

Current biotechnological developments in Belgium

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Influence of ZnO nano-inclusions on the transport properties of the CoSb3 skutterudite

International audienceAddition of nanoparticles into bulk materials is one of the strategies designed to synthesize thermoelectric materials with superior efficiency. The presence of nanoparticles is expected to act as a barrier of the heat transport due to an increased amount of nanoscopic interfaces and to enhance the electronic properties via quantum confinement effects. Here, this approach was applied to the skutterudite CoSb3 matrix in which different amounts of ZnO (2-12 wt.%) nanoparticles were introduced. The samples were densified by spark plasma sintering and characterized by X-ray diffraction and scanning electron microscopy. The thermoelectric properties were investigated in a broad temperature range (2-800 K) to better assess the influence of the ZnO nanoparticles. The nanostructured materials showed a significant enhancement in the thermopower values combined with a slight decrease in the thermal conductivity. A small amount of ZnO nanoparticles (2 wt.%) has a beneficial influence on the dimensionless thermoelectric figure of merit ZT suggesting that introducing stable oxide nanoparticles may be an interesting way to improve the thermoelectric properties of skutterudite compounds

Thermoelectric properties of In0.2Co4Sb12 skutterudites with embedded PbTe or ZnO nanoparticles

International audienceTransport properties of the skutterudite compound In0.2Co4Sb12 containing ZnO or PbTe nano-sized particles (2-12 wt%) were investigated by means of electrical resistivity, thermopower and thermal conductivity between 5 and 800 K. The composite powders were prepared by freeze-drying the nanoparticles with micron-sized In0.2Co4Sb12 powders. Densification was achieved by spark plasma sintering. All composites were characterized by X-ray powder diffraction and scanning electron microscopy. All the transport coefficients show similar temperature dependences suggesting little influence of the nature, semiconducting or insulating, of the nanoparticles. Both the electrical and the thermal conductivities decrease with increasing the PbTe or ZnO content. The impact of ZnO and PbTe on the thermal conductivity was modelled based on the Debye model taking into account a relaxation time constant reflecting phonon scattering by spherical nanoparticles. A maximum dimensionless figure of merit ZT of 1.05 at 700 K was achieved in a sample containing 2 wt% ZnO, a value quite similar to that of the reference In0.2-Co4Sb12 compound

Influence of Preparation Processing on the Transport Properties of Melt-Spun Sb2−x Bi x Te3+y .

International audienceIn this work, we present our attempt to improve the thermoelectric performance of melt-spun (MS) Sb2−x Bi x Te3+y samples densified by spark plasma sintering (SPS) through two different methods: (1) alignment of the MS ribbons in the SPS die; (2) repetitive SPS sintering. A microstructural study of the dense samples was performed by scanning electron microscopy supported by x-ray diffraction analyses. The thermoelectric and galvanomagnetic properties were measured in the direction perpendicular to the uniaxial pressing direction of SPS. Alignment of the ribbons gives rise to improved thermoelectric performances with an increase of up to 26% with respect to the reference sample, yielding a peak dimensionless figure of merit ZT value of 1.1 at 355 K. Yet, in contrast to recent studies, we observed a decrease in the thermoelectric efficiency of ∼10% in the Sb1.5Bi0.5Te3.1 sample prepared by double-SPS compared to the sample densified with a single SPS process. Nevertheless, all MS samples possess improved thermal and electrical properties compared to the reference samples, proving the positive influence of this method

High temperature thermoelectric properties of CoSb3 skutterudites with PbTe inclusions

International audienceNanostructured thermoelectric materials generally exhibit enhanced properties. PbTe-CoSb3 thermoelectric composites (0-8 wt% of PbTe) have been successfully prepared by freeze-drying nanoparticles of PbTe (6 nm in diameter, synthesized by laser fragmentation of micron-sized particles in water) with micron-sized skutterudite CoSb3 powders (similar to 5 mu m in diameter, synthesized by powder metallurgy), followed by spark plasma sintering. X-ray diffraction analyses and scanning electron microscopy observations have been performed. Microstructures reveal an agglomeration of the PbTe particles at the grain boundaries of CoSb3. Electrical resistivity, thermopower, and thermal conductivity measurements have been performed in the 300-800 K temperature range. The composites exhibit n-type conduction whereas the reference CoSb3 skutterudite is p-type. This change of conduction mode is attributed to substitution of Sb for a minute amount of Te in the composites. The influence of both PbTe nanoparticules and Te on the thermoelectric properties is discussed in detail