Diffusion in stochastic sandpiles

We study diffusion of particles in large-scale simulations of one-dimensional stochastic sandpiles, in both the restricted and unrestricted versions. The results indicate that the diffusion constant scales in the same manner as the activity density, so that it represents an alternative definition of an order parameter. The critical behavior of the unrestricted sandpile is very similar to that of its restricted counterpart, including the fact that a data collapse of the order parameter as a function of the particle density is possible, but with a narrow scaling region. We also develop a series expansion, in inverse powers of the density, for the collective diffusion coefficient in a variant of the stochastic sandpile in which the toppling rate at a site with n particles is n(n-1), and compare the theoretical prediction with simulation results.     

Homogeneous electro-mediated reduction of unsaturated compounds using Ni and Fe as mediators in DMF

The homogeneous electro-mediated reduction (HEMR) of several organic compounds (cyclohexene, cyclohexanone, acetophenone, benzaldehyde, styrene, linalool, 1,3-cyclohexadiene, citral, trans-4-phenyl-3-buten-2-one, and piperine) was carried out using Fe²⁺, Ni²⁺, and [Ni^II(bpy)]Br₂ (bpy=2,2′-bipyridine) as electron mediators. An electrochemical system composed of sacrificial anode (Fe, Ni or Zn), nickel cathode, NaI (0.2 M) as supporting electrolyte in DMF and an undivided cell, was used. A constant current ≤100 mA was applied with a maximum cell potential of 2.0 V. Non-conjugated olefins are not reactive, but ketones may be easily reduced to the respective alcohol. In the case of conjugated olefins and ketones, [Ni^II(bpy)]Br₂ or Ni²⁺ mediator presented good reactivity and selectivity in most cases. Fe²⁺ more efficiently mediates the reduction of carbonyl containing systems. Preliminary electroanalytical studies indicate the complexation of the organic substrate by Fe²⁺ and Ni²⁺ ions and [Ni^II(bpy)]Br₂ complex.     

Generalized derivations and additive theory II

We return to the theme of generalized derivations related to symmetric functions to correct the hypothesis of one of the main theorems of our first paper, so that all cases are now properly covered.     

Lupane triterpenoids,antioxidant potential and antimicrobial activity of Myrciaria floribunda (H. West ex Willd.) O. Berg.

Chemical composition of the methanol extract of Myrciaria floribunda leaves was investigated. The nor-lupane triterpenoids platanic acid and messagenic I acid were identified, along with other known triterpenoids (betulinic aldehyde, ursolic acid acetate and betulinic acid), a new lupane triterpenoid (2α,6α,30-trihydroxybetulinic acid) and the flavonoids catechin, quercetrin and mirycitrin. The structures were determined by spectroscopic methods (NMR, LC-MS, GC-MS). The major isolated compound was betulinic acid. The methanol extract and 2α,6α,30-trihydroxybetulinic acid were evaluated for their DPPH scavenging potential. The tested triterpenoid was one hundred times more active than betulinic acid, but less active than the extract. Screening for antimicrobial activity showed that the methanol extract was active against Staphylococcus aureus and Escherichia coli, but inactive against Candida albicans and Candida krusei, while 2α,6α,30-trihydroxybetulinic acid was inactive to all tested microorganisms.     

Electronic and structural properties of black phosphorene doped with Si,B and N

The electronic and structural properties of substitutional and doped phosphorene with B, N and Si were studied using first principles calculations based on density functional theory. Moreover, electronic and structural properties of functionalized phosphorene slowly increasing the concentration of doping was investigated. Phosphorene strongly binds with doped functionalization; B doped phosphorene is the most stable configuration studied. Si doped phosphorene maintains the semiconductor characteristic. B and N doped phosphorene present n-type and p-type semiconductors, respectively. Doped phosphorene with odd number of Si is a semiconductor material, doped phosphorene with an odd number of B has n-type semiconductor characteristic, and doped phosphorene with odd number of N atoms has a p-type semiconductor behaviour. Doped phosphorene with even number of Si has a metallic characteristic, while B and N doped phosphorene with even number present a semiconductor behaviour. This work reveals that phosphorene electronic properties could be changed by introducing the dopants on the system, and the properties are affected by the increasing number of dopants on phosphorene sheet.     

Bacterial nanocellulose containing diethylditiocarbamate bio-curatives: physicochemical characterization and drug delivery evaluation

Bacterial nanocellulose (BNC) is a natural biopolymer produced by different strains of acetic acid bacteria. Biocompatibility, lack of immunogenicity, mechanical strength and crystallinity make BNC a highly applicable product for drug delivery and wound dressing. Previously, we demonstrated that diethylditiocarbamate (DETC), a Superoxide Dismutase 1 inhibitor, incorporated into BNC bio-curatives was effective for treating Cutaneous leishmaniasis (CL) lesions, a parasitic disease caused by Leishmania. We herein investigated the interactions between DETC and BNC. For this purpose, DETC was incorporated into BNC and thermal analysis, x-ray diffraction and Scanning electron microscopy were performed. Furthermore, in vitro DETC release and stability tests as well as degradation studies were also performed. Our results show that DETC is well incorporated into BNC, however it is short lived as suggested by degradation experiments. Future use of BNC DETC-based bio-curatives for the treatment of CL shall require further development in order to increase stability of DETC in the bio-curative.

     

An HPLC method for the determination of adenosine diphosphate: An important marker of hexokinase activity in metabolic diseases

Hexokinases play a critical role in the cellular uptake and utilization of glucose. As such, they are of fundamental importance to all cells. By catalyzing glucose to produce glucose‐6‐phosphate, hexokinases control the first irreversible step of glucose metabolism and initiate all major pathways of glucose consumption. Our objective was to develop and validate highly sensitive and selective high‐performance liquid chromatography with photodiode array detector (HPLC‐PDA) assays allowing the determination of adenosine diphosphate, which was used for the determination of hexokinase activity. Samples were analyzed by HPLC‐PDA using a C₁₈ analytical column (250 × 4.6 mm) for chromatographic separation. Optimal detection was achieved based on isocratic elution with a mobile phase consisting of a mixture of sodium phosphate monobasic buffer and methanol. This method met all of the requirements of specificity, sensitivity, linearity, precision, accuracy and stability generally accepted in bioanalytical chemistry and was successfully applied to a study of hexokinase activity in an alloxan‐induced diabetic rat model. Determination of hexokinase activity will permit characterization of cellular metabolic state in many diseases, such as cancer and diabetes.     

Coordination of the natural ligand lapachol to iron(II): synthesis,theoretical study and antiproliferative activity

Transition Metal Chemistry - Lapachol is a natural naphthoquinone known for having a variety of biological properties, and in recent years, it has been used in the synthesis of metal complexes with...