Comparing Catalysts of the Direct Synthesis of Hydrogen Peroxide in Organic Solvent: is the Measure of the Product an Issue?

The direct synthesis of hydrogen peroxide has been for about 20 years a hot topic in \u201cgreen\u201d catalysis. Several methods, which are well established to measure the concentration of hydrogen peroxide in water are also applied to the analysis of reaction mixtures from the direct synthesis of H2O2. However, this step could not be always straightforward, because these mixtures contain almost invariably organic solvents and, sometimes, selectivity enhancers which can interfere in some, at the least, of the most popular titrimetric methods. This work presents a comparative investigation of iodometry, cerimetry, permanganometry (titrimetric methods) and spectrophotometric analysis of TiIV/H2O2 adduct, as applied to analysis of hydrogen peroxide produced by its direct synthesis. They account for more than 90 % of the competent literature since 2000. Their pros and cons are highlighted to provide a guideline for the choice of the best possible method of analysis and for the comparison of catalytic results assessed in different ways in the context of the direct synthesis of hydrogen peroxide

A local density functional for the short-range part of the electron-electron interaction

Motivated by recent suggestions --to split the electron-electron interaction into a short-range part, to be treated within the density functional theory, and a long-range part, to be handled by other techniques-- we compute, with a diffusion Monte Carlo method, the ground-state energy of a uniform electron gas with a modified, short-range-only electron-electron interaction \erfc(\mu r)/r, for different values of the cutoff parameter $\mu$ and of the electron density. After deriving some exact limits, we propose an analytic representation of the correlation energy which accurately fits our Monte Carlo data and also includes, by construction, these exact limits, thus providing a reliable ``short-range local-density functional''.Comment: 7 pages, 3 figure

Positron scattering from formic acid

We report on measurements of total cross sections for positron scattering from the fundamental molecule formic acid (HCOOH). In this case, the energy range of our experimental work is 0.3-50.2 eV. Our interpretation of these data was somewhat complicated by the fact that at room temperature, formic acid vapor consists of about 95% monomer and 5% dimer forms, so that the present cross sections represent an average for that ensemble. To assist us in interpreting the data, rigorous Schwinger multichannel level calculations for positron elastic scattering from the formic acid monomer were also undertaken. These calculations, incorporating an accurate model for the target polarization, are found to be in good qualitative agreement with our measured data, particularly when allowance is made for the target beam mixture (monomer versus dimer) in the experiment

Gravitational Entropy and Quantum Cosmology

We investigate the evolution of different measures of ``Gravitational Entropy'' in Bianchi type I and Lema\^itre-Tolman universe models. A new quantity behaving in accordance with the second law of thermodynamics is introduced. We then go on and investigate whether a quantum calculation of initial conditions for the universe based upon the Wheeler-DeWitt equation supports Penrose's Weyl Curvature Conjecture, according to which the Ricci part of the curvature dominates over the Weyl part at the initial singularity of the universe. The theory is applied to the Bianchi type I universe models with dust and a cosmological constant and to the Lema\^itre-Tolman universe models. We investigate two different versions of the conjecture. First we investigate a local version which fails to support the conjecture. Thereafter we construct a non-local entity which shows more promising behaviour concerning the conjecture.Comment: 20 pages, 7 ps figure

Myelodysplastic syndromes: the pediatric point of view.

Myelodysplastic syndromes (MDS) are clonal disorders of the multipotent hematopoietic stem cell characterized by ineffective hematopoiesis and associated with marrow hypercellularity, increased intramedullary cell death and peripheral cytopenias of varying severity. Patients with myelodysplasia have a propensity (20% to 30% of cases) to undergo transformation into acute myeloid leakemia (AML), and a large body of evidence indicates that MDS represent steps in the multiphasic evolution of AML. Progression of the disease is characterized by expansion of the abnormal clone and inhibition of normal hematopoiesis leading to deterioration of the blood cell count and/or development of AML. MDS are relatively unusual in childhood, representing only 3% of pediatric hematological malignancies, although it has been reported that up to 17% of pediatric AML cases may have a previous myelodysplastic phase. The first systematic attempt at morphological classification of MDS was provided by the French-American-British (FAB) group. However, the FAB classification of MDS is only partially applicable in children. Some variants are extremely rare or absent (refractory anemia with ring sideroblasts and chronic myelomonocytic leukemia), and other peculiar pediatric disorders, represented by juvenile chronic myelogenous leukemia (JCML) and the monosomy 7 syndrome, are not included. Moreover, since there is a partial overlap between pediatric MDS and myeloproliferative disorders and the variants occurring in young children have rather specific features, some confusion still surrounds the nosographical definition of childhood MDS, so that none of the proposed classifications are widely accepted and used. Characteristically, some genetic conditions such as Fanconi's anemia, Shwachman's and Down's syndromes predispose to the development of MDS in childhood. The most common variants of childhood MDS are represented by JCML and the monosomy 7 syndrome, both disorders typically occurring in young children. JCML is characterized by a spontaneous growth of granulocyte-macrophage progenitors that show a striking hypersensitivity to granulocyte-macrophage colony-stimulating factor. Clinical presentation resembles that of some myeloproliferative disorders, with massive organomegaly usually not observed in the classically reported variants of MDS. Clinical features of the monosomy 7 syndrome resemble those observed in JCML and a differential diagnosis between these two entities relies upon the higher percentage of fetal hemoglobin, the more pronounced decrease in platelet count and, in some cases, the lack of the peculiar cytogenetic abnormality in the latter. With the number of children being cured of cancer constantly rising, a significant increase in secondary or chemotherapy-related myelodysplasia is being observed, and these disorders represent a formidable challenge for pediatric hematologists due to their poor response to chemotherapy. As a matter of fact, owing to their biological heterogeneity and aggressive clinical course in childhood, all MDS variants pose serious difficulties for successful management. If a compatible donor is available, allogeneic bone marrow transplantation (BMT) becomes the treatment of choice and should be performed during the early stages of the disease. Supportive therapy, differentiative treatments and low-dose chemotherapy, while valuable alternative therapeutic options in adults, have limited application in pediatric patients. The role of intensive chemotherapy and autologous BMT has not yet been clearly defined, and the use of hematopoietic growth factors does not seem to have a significant influence on the natural history of the disease. In the future, new insights into the events leading to progressive genetic changes in the clonal population and into the molecular basis of these genetic lesions could result in interesting new therapeutic approaches directed either at the oncogenes involved in the pathogenesis of the disease, or at the cytokines and/or their receptors causing the abnormal differentiation and proliferation of the myelodysplastic clone

Control of multifunctional prosthetic hands by processing the electromyographic signal

The human hand is a complex system, with a large number of degrees of freedom (DoFs), sensors embedded in its structure, actuators and tendons, and a complex hierarchical control. Despite this complexity, the efforts required to the user to carry out the different movements is quite small (albeit after an appropriate and lengthy training). On the contrary, prosthetic hands are just a pale replication of the natural hand, with significantly reduced grasping capabilities and no sensory information delivered back to the user. Several attempts have been carried out to develop multifunctional prosthetic devices controlled by electromyographic (EMG) signals (myoelectric hands), harness (kinematic hands), dimensional changes in residual muscles, and so forth, but none of these methods permits the "natural" control of more than two DoFs. This article presents a review of the traditional methods used to control artificial hands by means of EMG signal, in both the clinical and research contexts, and introduces what could be the future developments in the control strategy of these devices

Alloantigen-induced human lymphocytes rendered nonresponsive by a combination of anti-CD80 monoclonal antibodies and Cyclosporin-A suppress mixed lymphocyte reaction in vitro

Induction of a state of long-term, alloantigen-specific T cell nonresponsiveness has significant implications for human transplantation. It has been previously described that alloantigen-specific anergy may be induced by addition of cyclosporin-A together with anti-CD80(B7-1) mAb to a MLR. In this study we endeavored to verify whether alloantigen-induced PBL rendered anergic by the addition of a combination of anti-B7 mAb and cyclosporin-A during a MLR had a suppressive effect when added to autologous lymphocytes activated in MLR. We found that: 1) the addition of cells rendered anergic by this procedure to a MLR suppress both proliferative and cytotoxic response of autologous responsive PBL to either the same or third-party stimulator cells; 2) the suppressive effect is limited to alloantigen-induced T cell activation, as addition of anergic cells does not influence mitogen- or antigen-induced proliferation of autologous responsive T cells; 3) nonresponsiveness of suppressed cells cannot be reversed by either subsequent restimulation with allogeneic cells or addition of exogenous IL-2 to the cultures; 4) the suppressive effect is apparently not due to secretion of anergic cell-derived soluble factors, but it seems to be dependent on cell-cell contact between anergic, responsive, and stimulator cells. These data suggest that: 1) the delivery of a direct signal mediated by anergic lymphocytes through a cell-cell contact is likely to be the mechanism responsible for the suppressive effect here described; 2) anergic cells may propagate alloantigen-specific tolerance to potentially responsive autologous lymphocytes. Preliminary experiments indicate that anti-CD86(B7-2) mAb may play a similar role in the generation of alloantigen-induced nonresponsiveness

Predicting the response to a triptan in migraine using deep attack phenotyping: A feasibility study

Background: Triptans, specific symptomatic medications for migraine, are not effective in a proportion of patients, or in all attacks, hence the importance of identifying predictors of response. Our aim was to investigate the association between the efficacy of oral frovatriptan 2.5 mg and clinical characteristics of migraine attacks. Methods: We enrolled 29 consecutive patients affected by migraine without aura at the Headache Center of \u201cMondino\u201d Institute of Pavia. Each patient was given a diary and asked to record prospectively the features of three consecutive migraine attacks while using frovatriptan. A generalized estimating equations approach was used to determine phenotypic features associated with the pain free response at 2 hours. Results: Participants provided complete data for 85 attacks. Thirty of these (34%) patients reported being pain free 2 hours after taking frovatriptan 2.5 mg intake. Unilateral pain, presence of phonophobia, presence of one or more cranial autonomic symptoms and presence of one or more premonitory symptom were each associated with being pain free at 2 hours. Conclusions: The response to frovatriptan was associated with particular features of the migraine attack, either before or during the pain phase of attacks. The data support larger studies to explore detailed attack phenotyping, with particular attention to early signs, to enable individualized treatment in migraine