•A continuous process of hydrothermal synthesis is used to prepare ZnO powders.•The effect of the KOH/Zn(II) on the ZnO crystallite characteristics is studied.•The ZnO crystal is considered as a ...cylindrical crystallite (XRD, Loüer method).•XRD and TEM characterizations are correlated with CFD simulation model results.•A schematic synoptic of ZnO crystal growth (size and morphology) is suggested.
In order to improve the knowledge on the nucleation and the growth mechanisms of metal oxides nanoparticles produced in supercritical water domain, ZnO was used as a “model” material. A continuous process of hydrothermal synthesis was employed to synthesize ZnO nanopowders (T=410°C and P=305bar) from Zn(NO3)2 and KOH solutions with different values of KOH/Zn(II) ratio from 0 to 8 in order to investigate the pH effect on the growth of ZnO nanocrystallite in terms of size and morphology. The samples were characterized by X-Ray Diffraction and Transmission Electronic Microscopy. ZnO crystal was considered as a cylindrical crystallite with a diameter D and height H. Especially, the aspect ratio D/H was already used to observe the change of ZnO nanoparticle shape correlated with TEM observations and results from a CFD simulation model. A schematic synoptic of the ZnO growth in supercritical domain is also presented.
Sn‐based SBA‐15 was prepared by reacting di‐n‐butyldimethoxystannane with SBA‐15 pretreated with trimethylchlorosilane (TMCS) to cap the external hydroxyl groups. Small‐angle X‐ray diffraction ...(SXRD), infrared spectroscopy (IR), nitrogen adsorption/desorption, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and inductively coupled plasma atomic emission (ICP‐AES) measurements allow us to propose that the organotin species are located within the pore channels of the mesoporous host. This novel material catalyzes selectively the coupling of CO2 with methanol to dimethyl carbonate (DMC). The reaction time–conversion dependence shows that a turnover number (TON) of 16 can be reached at 423 K under 20 MPa, which is among the highest reported so far in the absence of water traps. Moreover, as the catalytic activity is retained after recycling, even higher values can be obtained on a cumulative basis. A further TON increase is observed with the reaction temperature. Interestingly, the tin‐based SBA‐15 mesoporous material exhibits lower TONs if the TMCS pretreatment is left out. Therefore, the organotin species located outside the channels are far less active than those located within.
Well‐done SBA‐15! Post‐synthesis modification of SBA‐15 with di‐n‐butyldimethoxystannane leads to catalytic materials for the selective conversion of CO2 and methanol into dimethyl carbonate. The unexpected performance and resistance to leaching are assigned to the specific environment in the mesopores.
Abstract 863
In order to investigate the efficacy and the safety of imatinib in children and adolescents with untreated Philadelphia-positive CML, the CML working party of the Société Française des ...Cancers de l'enfant (SFCE) conducted an open label, multicentric phase IV study trial (Clinical Trials.gov.NCT00845221).
Patients less than 18 yrs of age with newly diagnosed CP CML were eligible. Imatinib was administered orally at a dose of 260 mg/m2 which is equivalent in terms of drug exposure to the total dose of 400 mg in adults. Forty four children (64% boys) with a median age of 11.5 yrs (range 10 months-17 yrs) have been enrolled from 15 French pediatric centres between July 2004 and December 2008. Side effects were reported prospectively using the NIH CTCv2.0 criteria.
Median follow up is currently 17 months (range:1-67). The complete hematologic response rate was 86% and 98% (ITT) at 3 months and 6 months, respectively. The rate of complete cytogenetic response (CCyR) was 62% (ITT) at 12 months. The rate of major molecular response (MMR) defined as a BCR-ABL/ABL ratio ≤ 0.1% according to the International Scale was 34% (ITT) at 12 months. The median daily dose of imatinib was close to the intended doses, 250 mg/m2 (range 176-405) with a median treatment duration of 16 months (2 w to 67 mo). Three pts (7%) had a dose reduction of more than 25% of the theoretic dose. Nine pts (20%) interrupted imatinib temporarily at least once for a median duration of dose interruption of 12 days (range 2-70). Ten pts (23%) discontinued imatinib. The reasons for discontinuation were the following: allogeneic HSCT in CCyR or MMR (2 pts) according to the investigator choice, adverse event (2 pts: muscle pain 1 pt, liver enzyme elevation 1 pt), disease progression or failure (6 pts: loss of CHR L248V mutation 1pt, loss of CCyR L384M mutation 1pt, no cytogenetic response 1 pt, no molecular response 1 pt, loss of MMR 2 pts). One of them (loss of hematologic response) transformed to blastic phase shortly after coming off study and died. Grade III or IV toxicity was recorded in 14 pts (32%). GradeIII-IV hematologic toxicity was recorded in 8 pts (18%) including neutropenia in 18% and thrombocytopenia in 5%. Nine pts (21%) developed grade III or IV non-hematologic toxicity: muscle pain (2.5%), arthralgia (5%), weight gain (13%), liver enzyme (GOT/GPT) increase (6.5%). Change of body height was observed during the first year of treatment with imatinib in the 22 pts with a sufficient follow-up: a significant decrease of height standard deviation scores (SDS) was observed with a median of the difference of -0.37 (range, -1.09 to +0.14)(p<0.0001) between the start of the treatment and 12 months later.
Imatinib is efficient in children and adolescent with previously untreated CML in early chronic phase. However, we report for the first time, a negative impact of imatinib on the growth in a cohort of children and adolescents treated with imatinib.
No relevant conflicts of interest to declare.
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► Numerical investigations performed on an original supercritical water device. ► Proposal of a CFD model for nanoparticle size determination using a population balance approach. ► ...Choice of ZnO as a model compound. Showing of models for reaction kinetics, thermodynamics and nucleation.
Continuous hydrothermal flow synthesis process has shown great advantages concerning the control of particle size and morphology through the optimization of supercritical water processing parameters. In particular, micromixing is a key issue of the process for controlling the nucleation mechanism. A Computational Fluid Dynamics (CFD) model is suggested for nanoparticle size determination using a population balance approach. Models for reaction kinetics, thermodynamics, nucleation and growth are presented. The effects of base concentration and hydrodynamics are investigated. Results show that the CFD may be valuable simulation tool for controlling the size and the shape of nanoparticles from a good adjustment of processing parameters. However, some additional knowledge on nucleation, crystal growth and aggregation mechanisms are useful in order to get a better agreement.
Aging is normally associated with increased predictability of neurophysiological processes. To test the related prediction of age-related increase in the Hurst exponent,
H, of functional MRI time ...series, and its possible cholinergic mechanisms, two groups of healthy participants (old mean age
=
65 years; young mean age
=
22 years;
N
=
11 per group) were scanned twice at rest, following placebo and a muscarinic receptor antagonist, scopolamine 0.3
mg. Older age was associated with significant increase in
H of fMRI time series in bilateral hippocampus. Similarly, scopolamine was associated with increased
H in left hippocampus; and there was an age-by-drug interaction in medial temporal lobe whereby older participants specifically had increased
H following scopolamine. Scopolamine also enhanced fronto-hippocampal low-frequency coherence, and this could be correlated with its effect on hippocampal
H. Thus, increased persistence of hippocampal dynamics in older subjects is demonstrable by resting fMRI; scopolamine mimics these effects, especially in older subjects, implying a cholinergic mechanism for age-related change; and cholinergic effects on hippocampal dynamics are associated with enhanced functional connectivity between frontal cortex and hippocampus.
This paper reports the sintering behavior of synthetic inorganic carbonates chemically identical to barytocalcite (BaCa(CO3)2, 8.1wt.% C), kutnahorite (CaMn(CO3)2, 11.1mass% C) and rhodochrosite ...(MnCO3, 10.5wt.% C) for 14C immobilization. As carbonates are time–temperature dependently subjected to decarbonation due to the loss of carbon dioxide, spark plasma sintering (SPS) appeared to be the most suitable method for the study. It was shown that densification and decarbonation are overlapping phenomena for kutnahorite and rhodochrosite, lowering the carbon final content, whereas barytocalcite was successfully densified without carbon loss. Barytocalcite pellets of 30mm diameter with a relative density of 92% and a carbon content of 7.78±0.28wt.% were obtained. The study highlighted the role of sintering pressure in carbon dioxide volatilization.
The aim of the present study was to explore the cerebral substrates of episodic memory disorders in Alzheimer's disease (AD) and investigate patients' hyperactivations frequently reported in the ...functional imaging literature. It remains unclear whether some of these hyperactivations reflect real increased activity or deactivation disturbances in the default mode network (DMN). Using positron emission tomography ((15)O-H(2)O), cerebral blood flow was measured in 11 AD patients and 12 healthy elderly controls at rest and during encoding and stem-cued recall of verbal items. Subtractions analyses between the target and control conditions were performed and compared between groups. The average signal was extracted in regions showing hyperactivation in AD patients versus controls in both contrasts. To determine whether hyperactivations occurred in regions that were activated or deactivated during the memory tasks, we compared signal intensities between the target conditions versus rest. Our results showed reduced activation in AD patients compared to controls in several core episodic memory regions, including the medial temporal structures, during both encoding and retrieval. Patients also showed hyperactivations compared to controls in a set of brain areas. Further analyses conducted on the signal extracted in these areas indicated that most of these hyperactivations actually reflected a failure of deactivation. Indeed, whereas almost all of these regions were significantly more activated at rest than during the target conditions in controls, only one region presented a similar pattern of deactivation in patients. Altogether, our findings suggest that hyperactivations in AD must be interpreted with caution and may not systematically reflect increased activity. Although there has been evidence supporting the existence of genuine compensatory mechanisms, dysfunction within the DMN may be responsible for part of the apparent hyperactivations reported in the literature on AD.
Objective
Repair of demyelinated axons in diseases such as multiple sclerosis requires activation of the myelination program in existing or newly recruited oligodendrocyte precursor cells (OPCs). The ...control of OPC differentiation and initiation of myelination during repair is poorly understood. In this study, we test the ability of anti–LINGO‐1 reagents to promote myelination in vitro and remyelination in the rodent adult central nervous system in vivo.
Methods
The effects of LINGO‐1 antagonists on the differentiation of OPCs and the promotion of myelination has been assayed using a combination of coculture and slice culture preparations. Using three different animal models of demyelination and remyelination, we morphologically and functionally assessed the effects of LINGO‐1 antagonists on OPC differentiation and myelin repair.
Results
The data indicate that in vitro treatment with antagonists of LINGO‐1 promote OPC differentiation and myelination, whereas in vivo remyelination is accelerated in lysophosphatidylcholine‐ or cuprizone‐induced demyelination. This remyelination is associated with enhanced OPC differentiation and functional recovery of conduction velocities in demyelinated axons.
Interpretation
Our studies demonstrate that LINGO‐1 antagonism promotes OPC differentiation and remyelination, and suggest LINGO‐1 functions as an inhibitor of OPC differentiation to retard central nervous system remyelination. Ann Neurol 2009;65:304–315
•A continuous process of hydrothermal synthesis is used to prepare ZnO powders.•The effect of Zn(II) on the ZnO crystallite characteristics is studied.•The ZnO crystal is considered as a cylindrical ...crystallite (XRD, Loüer method).•Growth units and oriented attachment concepts are taken into account.•A schematic synoptic of ZnO crystal growth (size and morphology) is suggested.
The metal salt concentration effect on the size and morphology of ZnO NPs was highlighted through its synthesis thanks to a continuous one-step method at 401±15°C and 306±8bar. Experiments were performed from Zn(NO3)2 and KOH as reactants in concentration ranges of 10–480mM and 40–1920mM, respectively. A constant KOH/Zn(NO3)2 ratio of 4 was fixed in order to maintain a constant pH value between 12.5 and 13.0. The as-prepared NPs were characterized by X-ray diffraction and (high-resolution) transmission electron microscopy. Based on Loüer's method, ZnO crystal exhibiting a hexagonal structure was considered as cylinder with a diameter D and a height H. The D/H parameter has already been used to observe the change of ZnO crystallite shape and correlated with (HR)TEM observations. The evolutions of crystal size and morphology according to Zn(NO3)2 in alkali medium are investigated and the particle growth mechanisms in supercritical water are discussed.
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