34 research outputs found
Cortisol, testosterone, and pain levels among patients undergoing McKenzie therapy and suboccipital relaxation
Sedentary lifestyle and the development of consumer electronics, often associated with a faulty posture, arewidespread factors contributing to cervical spine dysfunction (CSD). The purpose of our study is to comparetwo methods of physical therapy of CSD: suboccipital relaxation and the McKenzie method. Their effect onperceived pain level and life quality was assessed using VAS and NDI scores. Serum levels of biochemicalstress indicators like testosterone and cortisol were also evaluated. Eighty-six adult patients were dividedinto two groups: Group A and Group B. Group A included 42 patients treated using the McKenzie method.Group B consisted of 44 patients who underwent suboccipital relaxation. The therapy in both groups includedthree treatment sessions over a six-week period. Testosterone and cortisol levels were assessed usingthe ELISA technique. Pain evaluation was performed using the Visual Analogue Scale (VAS). The disabilitylevel was evaluated with the Neck Disability Index (NDI). In both groups, a similar improvement in VASand NDI scores was observed. A distinct cortisol level decrease in patients subjected to the suboccipitalrelaxation was noticed, while the McKenzie method did not affect cortisolaemia significantly. We did notnotice any difference in testosterone levels between the two groups. Both treatment methods contributedtowards clinical improvement in our patients, represented by the drop in VAS and NDI scores. We alsoobserved a biochemical improvement: decreased cortisol level in the group treated with suboccipitalrelaxation. Due to the important role of testosterone and cortisol in the pathogenesis of chronic pain, ourstudy should be the pilot experience on their use as markers in CSD
Elucidation of role of graphene in catalytic designs for electroreduction of oxygen
Graphene is, in principle, a promising material for consideration as
component (support, active site) of electrocatalytic materials, particularly
with respect to reduction of oxygen, an electrode reaction of importance to
low-temperature fuel cell technology. Different concepts of utilization,
including nanostructuring, doping, admixing, preconditioning, modification or
functionalization of various graphene-based systems for catalytic
electroreduction of oxygen are elucidated, as well as important strategies to
enhance the systems' overall activity and stability are discussed
Evaluation of Reduced-Graphene-Oxide Aligned with WO3-Nanorods as Support for Pt Nanoparticles during Oxygen Electroreduction in Acid Medium
Hybrid supports composed of chemically-reduced graphene-oxide-aligned with
tungsten oxide nanowires are considered here as active carriers for dispersed
platinum with an ultimate goal of producing improved catalysts for
electroreduction of oxygen in acid medium. Here WO3 nanostructures are expected
to be attached mainly to the edges of graphene thus making the hybrid structure
not only highly porous but also capable of preventing graphene stacking and
creating numerous sites for the deposition of Pt nanoparticles. Comparison has
been made to the analogous systems utilizing neither reduced graphene oxide nor
tungsten oxide component. By over-coating the reduced-graphene-oxide support
with WO3 nanorods, the electrocatalytic activity of the system toward the
reduction of oxygen in acid medium has been enhanced even at the low Pt loading
of 30 microg cm-2. The RRDE data are consistent with decreased formation of
hydrogen peroxide in the presence of WO3. Among important issues are such
features of the oxide as porosity, large population of hydroxyl groups, high
Broensted acidity, as well as fast electron transfers coupled to unimpeded
proton displacements. The conclusions are supported with mechanistic and
kinetic studies involving double-potential-step chronocoulometry as an
alternative diagnostic tool to rotating ring-disk voltammetry.Comment: arXiv admin note: text overlap with arXiv:1805.0315
Towards 'Pt-free' Anion-Exchange Membrane Fuel Cells: Fe-Sn Carbon Nitride-Graphene 'Core-Shell' Electrocatalysts for the Oxygen Reduction Reaction
We report on the development of two new Pt-free electrocatalysts (ECs) for
the oxygen reduction reaction (ORR) based on graphene nanoplatelets (GNPs). We
designed the ECs with a core-shell morphology, where a GNP core support is
covered by a carbon nitride (CN) shell. The proposed ECs present ORR active
sites that are not associated to nanoparticles of metal/alloy/oxide, but are
instead based on Fe and Sn sub-nanometric clusters bound in coordination nests
formed by carbon and nitrogen ligands of the CN shell. The performance and
reaction mechanism of the ECs in the ORR are evaluated in an alkaline medium by
cyclic voltammetry with the thin-film rotating ring-disk approach and confirmed
by measurements on gas-diffusion electrodes. The proposed GNP-supported ECs
present an ORR overpotential of only ca. 70 mV higher with respect to a
conventional Pt/C reference EC including a XC-72R carbon black support. These
results make the reported ECs very promising for application in anion-exchange
membrane fuel cells. Moreover, our methodology provides an example of a general
synthesis protocol for the development of new Pt-free ECs for the ORR having
ample room for further performance improvement beyond the state of the art
Photoactive Materials for Decomposition of Organic Matter Prior to Water Analysis—A Review Containing Original Research
Water plays a fundamental role in meeting the basic needs of society. Surface waters contain numerous organic pollutants, such as pesticides, drugs, and surfactants. The use of photolysis processes in organic matter degradation not only has practical applications in wastewater treatment but is also of major importance in the pretreatment of samples prior to the trace analysis of numerous analytes. The heterogeneous degradation is simple to implement prior to ultra-traces determination and is the only one allowed before the speciation analysis. Speciation analysis is currently the most important environmental challenge. The analysis of water, including tests associated with wastewater pretreatment and the monitoring of aqueous ecosystems, is the largest segment of environmental analysis. In the trace analysis of water, organic compounds are the principal interfering compounds reducing the quality of the obtained results or even preventing the determination of the examined analytes altogether. Some analytical techniques do not perform well in the presence, for example, of surfactants, so mineralization is sometimes required. Advanced oxidation processes are used to remove interfering organic compounds. The oxidation can be performed using homogenous photolysis (UV mineralization with hydrogen peroxide addition), while heterogenous photolysis using semiconductors helps to increase the removal efficiency of interferents dissolved in water. Utilizing semiconductor nanostructured materials as photocatalysts has been shown to be effective for the adequate removal of a wide spectrum of pollutants in water. Several semiconductor systems are used in the degradation of organic compounds, e.g., TiO2, Fe3O4, WO3, Fe2O3, ZnO, and mixtures of these oxides enriched with various precious metals, such as silver or gold. It is very challenging to manage the selectivity and reduction power so that organic compounds can be degraded but without disturbing the speciation of As, Cr, or Tl. Chemical modification of samples and the selection of semiconductor layers, light wavelength, and pH allow for the targeted degradation of specific compounds but may also indirectly affect the analysis of water samples. This review is a presentation of the state of the art of photocatalysis as a simple and effective technique for sample pretreatment in ultra-trace and speciation analysis and its critical as well as unpublished data related to this topic