501 research outputs found
Growth of Green Deli Water Apple (Syzygium Samarangense (Blume) Merr. & Perry) on Difference Plant Materials and IBA Concentrations
The objectives of this research was to study the growth of green deli water apple (Syzygium samarangense (Blume) Merr. & Perry on difference plant materials and IBA concentrations. This research was conducted at experimental field of Agriculture Faculty, University of North Sumatera, Medan on August until October 2015, using randomized block design with two factors, i.e cutting plant materials (branches with shoot and branches without shoot) and IBA concentration (0; 50; 100; and 150 ppm) with 3 replications. The result showed that the growth of green deli water apple with branches without shoot better than branches with shoot, the application of 100 ppm IBA concentration has given better effect than the other treatments for growth of green deli water apple and the best combination for growth of green deli water apple was branches without shoot and 100 ppm IBA concentration
Phase Stability and Fast Ion Conductivity in the Hexagonal LiBH4-LiBr-LiCl Solid Solution
This study shows a flexible system that offers promising candidates for Li-based solid-state electrolytes. The Br− substitution for BH4 − stabilizes the hexagonal structure of LiBH4 at room temperature (RT), whereas Cl− is soluble only at higher temperatures. Incorporation of chloride in a hexagonal solid solution leads to an increase in the energy density of the system. For the first time, a stable hexagonal solid solution of LiBH4 containing both Cl− and Br-halide anions has been obtained at RT. The LiBH4−LiBr−LiCl ternary phase diagram has been determined at RT by X-ray diffraction coupled with a Rietveld refinement. A solubility of up to 30% of Cl− in the solid solution has been established. The effect of halogenation on the Li-ion conductivity and electrochemical stability has been investigated by electrochemical impedance spectroscopy and cyclic voltammetry. Considering the ternary samples, h-Li(BH4)0.7(Br)0.2(Cl)0.1 composition showed the highest value for conductivity (1.3 × 10−5 S/cm at 30 °C), which is about 3 orders of magnitude higher than that for pure LiBH4 in the orthorhombic structure. The values of Li-ion conductivity at RT depend only on the BH4 − content in the solid solution, suggesting that the Br/Cl ratio does not affect the defect formation energy in the structure. Chloride anion substitution in the hexagonal structure increases the activation energy, moving from about 0.45 eV for samples without Cl− ions in the structure up to about 0.63 eV for h-Li(BH4)0.6(Br)0.2(Cl)0.2 compositions, according to the Meyer−Neldel rule. In addition to increasing Li-ion conductivity, the halogenation also increases the thermal stability of the system. Unlike for the Liion conductivity, the Br/Cl ratio influences the electrochemical stability: a wide oxidative window of 4.04 V versus Li+/Li is reached in the Li−Br system while further addition of Cl is a trade-off between oxidative stability and weight reduction. The halogenation allows both binary and ternary systems operating below 120 °C, thus suggesting possible applications of these fast ion conductors as solid-state electrolytes in Li-ion batteries
Acetaldehyde binding energies: a coupled experimental and theoretical study
Acetaldehyde is one of the most common and abundant gaseous interstellar
complex organic molecules, found in cold and hot regions of the molecular
interstellar medium. Its presence in the gas-phase depends on the chemical
formation and destruction routes, and its binding energy (BE) governs whether
acetaldehyde remains frozen onto the interstellar dust grains or not. In this
work, we report a combined study of the acetaldehyde BE obtained via laboratory
TPD (Temperature Programmed Desorption) experiments and theoretical quantum
chemical computations. BEs have been measured and computed as a pure
acetaldehyde ice and as mixed with both polycrystalline and amorphous water
ice. Both calculations and experiments found a BE distribution on amorphous
solid water that covers the 4000--6000 K range, when a pre-exponential factor
of is used for the interpretation of the experiments.
We discuss in detail the importance of using a consistent couple of BE and
pre-exponential factor values when comparing experiments and computations, as
well as when introducing them in astrochemical models. Based on the comparison
of the acetaldehyde BEs measured and computed in the present work with those of
other species, we predict that acetaldehyde is less volatile than formaldehyde,
but much more than water, methanol, ethanol, and formamide. We discuss the
astrochemical implications of our findings and how recent astronomical high
spatial resolution observations show a chemical differentiation involving
acetaldehyde, which can easily explained as due to the different BEs of the
observed molecules.Comment: 12 pages, 6 figure
Molecular Catalysts with Intramolecular Re-O Bond for Electrochemical Reduction of Carbon Dioxide
Detection of lithium plating in li-ion cell anodes using realistic automotive fast-charge profiles
The widespread use of electric vehicles is nowadays limited by the “range anxiety” of the customers. The drivers’ main concerns are related to the kilometric range of the vehicle and to the charging time. An optimized fast-charge profile can help to decrease the charging time, without degrading the cell performance and reducing the cycle life. One of the main reasons for battery capacity fade is linked to the Lithium plating phenomenon. This work investigates two methodologies, i.e., three-electrode cell measurement and internal resistance evolution during charging, for detecting the Lithium plating conditions. From this preliminary analysis, it was possible to develop new Multi-Stage Constant-Current profiles, designed to improve the performance in terms of charging time and cells capacity retention with respect to a reference profile. Four new profiles were tested and compared to a reference. The results coming from the new profiles demonstrate a simultaneous improvement in terms of charging time and cycling life, showing the reliability of the implemented methodology in preventing Lithium plating
Molecular signature of retinoic acid treatment in acute promyelocytic leukemia
Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia characterized by a block of differentiation at the promyelocytic stage. APL patients respond to pharmacological concentrations of all-trans retinoic acid ( RA) and disease remission correlates with terminal differentiation of leukemic blasts. The PML/RAR oncogenic transcription factor is responsible for both the pathogenesis of APL and for its sensitivity to RA. In order to identify physiological targets of RA therapy, we analysed gene expression profiles of RA-treated APL blasts and found 1056 common target genes. Comparing these results to those obtained in RA-treated U937 cell lines revealed that transcriptional response to RA is largely dependent on the expression of PML/RAR. Several genes involved in the control of differentiation and stem cell renewal are early targets of RA regulation, and may be important effectors of RA response. Modulation of chromatin modifying genes was also observed, suggesting that specific structural changes in local chromatin domains may be required to promote RA-mediated differentiation. Computational analysis of upstream genomic regions in RA target genes revealed nonrandom distribution of transcription factor binding sites, indicating that specific transcriptional regulatory complexes may be involved in determining RA response
Selective Synthesis of a Salt and a Cocrystal of the Ethionamide-Salicylic Acid System
Herein is presented a rare example of salt/cocrystal polymorphism involving the adduct between ethionamide (ETH) and salicylic acid (SAL). Both the salt and cocrystal forms have the same stoichiometry and composition and are both stable at room temperature. The synthetic procedure was successfully optimized in order to selectively obtain both polymorphs. The two adducts' structures were thoroughly investigated by means of single-crystal X-ray diffraction, solid-state NMR spectroscopy, and density functional theory (DFT) calculations. From the solid-state NMR point of view, the combination of mono- and multinuclear experiments (1H MAS, 13C and 15N CPMAS, 1H-{14N} D-HMQC, 1H-14N PM-S-RESPDOR) provided undoubted spectroscopic evidence about the different positions of the hydrogen atom along the main N\ub7\ub7\ub7H\ub7\ub7\ub7O interaction. In particular, the 1H-14N PM-S-RESPDOR allowed N-H distance measurements through the 1H detected signal at a very high spinning speed (70 kHz), which remarkably agree with those derived by DFT optimized X-ray diffraction, even on a natural abundance real system. The thermodynamic relationship between the salt and the cocrystal was inquired from the experimental and computational points of view, enabling the characterization of the two polymorphs as enantiotropically related. The performances of the two forms in terms of dissolution rate are comparable to each other but significantly higher with respect to the pure ETH
Sequential valproic acid/all-trans retinoic acid treatment reprograms differentiation in refractory and high risk acute myeloid leukemia.
Epigenetic alterations of chromatin due to aberrant histone deacetylase (HDAC) activity and transcriptional silencing of all-trans retinoic acid (ATRA) pathway are events linked to the pathogenesis of acute myeloid leukemia (AML) that can be targeted by specific treatments. A pilot study was carried out in eight refractory or high-risk AML patients not eligible for intensive therapy to assess the biological and therapeutic activities of the HDAC inhibitor valproic acid (VPA) used to remodel chromatin, followed by the addition of ATRA, to activate gene transcription and differentiation in leukemic cells. Hyperacetylation of histones H3 and H4 was detectable at therapeutic VPA serum levels (>or=50 microg/mL) in blood mononuclear cells from seven of eight patients. This correlated with myelomonocytic differentiation of leukemic cells as revealed by morphologic, cytochemical, immunophenotypic, and gene expression analyses. Differentiation of the leukemic clone was proven by fluorescence in situ hybridization analysis showing the cytogenetic lesion +8 or 7q- in differentiating cells. Hematologic improvement, according to established criteria for myelodysplastic syndromes, was observed in two cases. Stable disease and disease progression were observed in five and one cases, respectively. In conclusion, VPA-ATRA treatment is well tolerated and induces phenotypic changes of AML blasts through chromatin remodeling. Further studies are needed to evaluate whether VPA-ATRA treatment by reprogramming differentiation of the leukemic clone might improve the response to chemotherapy in leukemia patients
The novel CXCR4 antagonist POL5551 mobilizes hematopoietic stem and progenitor cells with greater efficiency than Plerixafor
Mobilized blood has supplanted bone marrow (BM) as the primary source of hematopoietic stem cells for autologous and allogeneic stem cell transplantation. Pharmacologically enforced egress of hematopoietic stem cells from BM, or mobilization, has been achieved by directly or indirectly targeting the CXCL12/CXCR4 axis. Shortcomings of the standard mobilizing agent, granulocyte colony-stimulating factor (G-CSF), administered alone or in combination with the only approved CXCR4 antagonist, Plerixafor, continue to fuel the quest for new mobilizing agents. Using Protein Epitope Mimetics technology, a novel peptidic CXCR4 antagonist, POL5551, was developed. In vitro data presented herein indicate high affinity to and specificity for CXCR4. POL5551 exhibited rapid mobilization kinetics and unprecedented efficiency in C57BL/6 mice, exceeding that of Plerixafor and at higher doses also of G-CSF. POL5551-mobilized stem cells demonstrated adequate transplantation properties. In contrast to G-CSF, POL5551 did not induce major morphological changes in the BM of mice. Moreover, we provide evidence of direct POL5551 binding to hematopoietic stem and progenitor cells (HSPCs) in vivo, strengthening the hypothesis that CXCR4 antagonists mediate mobilization by direct targeting of HSPCs. In summary, POL5551 is a potent mobilizing agent for HSPCs in mice with promising therapeutic potential if these data can be orroborated in humans
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