Search results for " ACTIVATION"

Activated carbon from hydrolysis lignin: Effect of activation method on carbon properties

2022

This study presents the effects of different activation methods to produce activated carbon from the hydrolysis lignin. Pretreatment of the feedstock with common mineral acids (HCL, HNO3, and H3PO4), different steam rates for physical activation, and different chemical activating agents (ZnCl2, Na2CO3, and KOH) for chemical activation were investigated. The pretreated biomass was carbonized and activated in one-stage process and the surface characteristics, such as total pore volume, pore size distribution and specific surface area, were investigated. The results showed that the activated carbon surface properties were not greatly affected by acid pretreatment. Brunauer-Emmett-Teller (BET) …

Linkage between inflammation, endothelial activation and renal function in kidney transplantation.

2006

Allosteric regulation by Mg2+ of the vacuolar H(+)-PPase from Acer pseudoplatanus cells. Ca2+/Mg2+ interactions.

1996

The tonoplast H(+)-PPase was previously characterized in Acer pseudoplatanus cells (Pugin et al (1991) Plant Sci 73, 23-34; Fraichard et al (1993) Plant Physiol Biochem 31, 349-359). Tonoplast vesicles were obtained from vacuoles isolated from protoplasts of A pseudoplatanus suspension cultures and used to study kinetic effects of Mg2+ and Ca2+ on PPi hydrolysis. The concentrations of ionic species (free Mg2+, free PPi, and MgPPi complexes) were calculated with apparent dissociation constants of 55.3 microM for MgPPi and 59.6 microM for CaPPi. Our results indicated that the substrate of the tonoplast PPase was a MgPPi complex and that free Mg2+ was essential for PPi hydrolysis. With fixed f…

Electrothermal Atomic Absorption Determination of Chromium in Sediments

1999

Abstract An electrothermal atomic absorption spectrometric method has been developed to determine total chromium concentration in natural sediment samples. Samples were mineralized by dry ashing at 550°C and fused at 1100°C for 30 min with lithium metaborate. Dissolved samples were injected in graphite tubes, mineralized at 1100°C, and atomized at 2600°C. Standard addition calibration made unnecessary the use of chemical modifiers. The method provided a limit of detection from 23 to 45 ng liter −1 . The relative standard deviation for chromium determination was between 3 and 14%. Results obtained for a standard reference material agree well with the certified value. A series of natural samp…

Validation of a method for neutron dosimetry and spectrometry using neutron activation of metal discs

2009

A technique for neutron dosimetry and spectrometry based on neutron activation of different metal discs has been studied. After exposure to a neutron field, the radionuclides produced in the discs are detected using low-level gamma-ray spectrometry and the neutron spectrum is obtained using a spectrum unfolding technique. In order to validate the method, irradiation was performed in a well-characterised (252)Cf neutron reference field. Furthermore, the detector was used to determine the neutron fluence rate and spectrum at a storage place for MOX nuclear fuel. The results of the two measurements are reported and discussed.

Neutron flux and gamma dose measurement in the BNCT irradiation facility at the TRIGA reactor of the University of Pavia

2018

Abstract University of Pavia is equipped with a TRIGA Mark II research nuclear reactor, operating at a maximum steady state power of 250 kW. It has been used for many years to support Boron Neutron Capture Therapy (BNCT) research. An irradiation facility was constructed inside the thermal column of the reactor to produce a sufficient thermal neutron flux with low epithermal and fast neutron components, and low gamma dose. In this irradiation position, the liver of two patients affected by hepatic metastases from colon carcinoma were irradiated after borated drug administration. The facility is currently used for cell cultures and small animal irradiation. Measurements campaigns have been ca…

Direct arylation of heteroaromatic compounds with congested, functionalised aryl bromides at low palladium/triphosphane catalyst loading.

2011

International audience; A new ferrocenyl triphosphane ligand associated to palladium was found to be an efficient catalyst for the direct coupling of highly congested, functionalised aryl bromides with a variety of heteroarenes. These coupling reactions can generally be performed by using a low-loading (0.1-0.5 mol%) of the catalyst. The present protocol tolerates important and useful functional groups, which allows for further elaboration into more sophisticated heterocyclic molecules. The straightforward arylation of heteroaromatic compounds with congested ortho-substituted aryl bromides may permit further convergent syntheses of diverse ligands, biologically active molecules and molecula…

Reversible O-H bond activation by an intramolecular frustrated Lewis pair

2019

The interactions of the O–H bonds in alcohols, water and phenol with dimethylxanthene-derived frustrated Lewis pairs (FLPs) have been probed. Within the constraints of this backbone framework, the preference for adduct formation or O–H bond cleavage to give the corresponding zwitterion is largely determined by pKa considerations. In the case of the PPh2/B(C6F5)2 system and p-tBuC6H4OH, an equilibrium is established between the two isomeric forms which allows the thermodynamic parameters associated with zwitterion formation via O–H bond cleavage to be probed. peerReviewed

Altered prefrontal cortex responses in older adults with subjective memory complaints and dementia during dual‐task gait : an fNIRS study

2021

People with cognitive impairments show deficits during physical performances such as gait, in particular during cognitively‐challenging conditions (i.e. dual‐task gait [DTG]). However it is unclear if people at risk of dementia, such as those with subjective memory complaints (SMC), also display gait and central deficits associated with DTG. In this study, we investigated the effects of single‐ and dual‐task gait (STG and DTG), on left prefrontal cortex (PFC) activation in elderly people with subjective memory complaints (SMC) and Dementia. 58 older adults (aged 65‐94 yrs; 26 Healthy; 23 SMC; 9 Dementia) were recruited. Gait spatiotemporal characteristics (i.e. stride velocity and length) w…

The state of art of biological processes in paternal care

2014

This review of the state of art aimed to present the most recent data on neuronal, neurochemical, hormonal and genetic bases of paternal care using MEDLINE and PsycInfo databases (1970-2013). An integrated model of biological substrates that assist men in the transition to fatherhood is presented. Guided by a genetic background, hypothalamic-midbrain-limbic-paralimbic-cortical circuits were found to be activated in fathers when infant stimuli are presented. A set of specifi c neuropeptides and steroid hormones are produced and seem to be related to brain activation, potentiating the paternal phenotype. Together, genetic, brain and hormonal processes suggest the existence of biological bases…