The effects of different precipitant agents on the formation of alumina-magnesia composite powders as the magnesium aluminate spinel precursor

Al₂O₃/MgO composite powders were synthesized via a partially wet chemical method. The effects of precipitant agent on the morphology, size and chemical composition of the resultant powders were investigated. The structures of rod-like with polygonal prism surface, platelet-like and uniform spherical Mg-compound particles were successfully prepared by using ammonium hydrogen carbonate, sodium hydroxide and ammonia water as precipitant agents, respectively. Analysis results proved that using ammonium hydrogen carbonate as precipitant agent produced nesquehonite (MgCO₃·3H₂O) Mg-compounds but in the case of other two precipitant agents, Mg-compound particles with magnesium hydroxide (Mg(OH)₂) chemical composition were obtained. The morphological features of MgO particles in Al₂O₃/MgO composite powders were the same as individual Mg-compound particles. Furthermore, conversion of the Al₂O₃/Mg-compound precursor synthesized with ammonia water to pure magnesium aluminate spinel particles was studied. The precursor converted to pure magnesium aluminate spinel phase with 220?nm particle size at 1200?°C.     

Cationic RuII Cyclopentadienyl Complexes with Antifungal Activity against Several Candida Species

Fungal infections, including those caused by antifungal-resistant Candida, are a very challenging health problem worldwide. Whereas different ruthenium complexes were previously studied for their anti-Candida potential, Ru-cyclopentadienyl complexes were overlooked. Here, we report an antifungal activity assessment of three Ru-cyclopentadienyl complexes with some insights into their potential mode of action. Among these complexes, only the cationic species [Ru-ACN]⁺ and [Ru-ATZ]⁺ displayed a significant antifungal activity against different Candida strains, notably against the ones that did not respond to one of the most currently used antifungal drugs fluconazole (FCZ). However, no apparent activity was observed for the neutral species, Ru−Cl, thus indicating the important role of the cationic backbone of these complexes in their biological activity. We suggest that reactive oxygen species (ROS) generation might be involved in the mechanism of action of these complexes as, unlike neutral Ru−Cl, [Ru-ACN]⁺ and [Ru-ATZ]⁺ could generate intracellular concentration-dependent ROS. We also observed a correlation between the ruthenium cellular uptake, ROS generation and fungal growth inhibitory activity of the compounds. Furthermore, docking simulations showed that the CYP51 enzyme can form more energetically favorable complexes with [Ru-ATZ]⁺ than fluconazole (FCZ); this suggests that CYP51 inhibition could also be considered as a potential mode of action.     

Selective and facile oxidative desulfurization of thioureas and thiobarbituric acids with singlet molecular oxygen generated from trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane

An efficient and facile procedure using trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane has been developed for oxidative desulfurization of thioureas and thiobarbituric acids. The reactions proceeded smoothly very fast under mild conditions in basic media at room temperature to afford the respective ureas in excellent yields. Simple procedure and work up, mild conditions, high yields, short reaction times, use of highly potent and non-toxic oxidant are the main merits of the present method.     

The effects of TEOS on the microstructure and phase evolutions of YAG phase by formation of alumina/yttria core‐shell structures

In this work, pure yttrium aluminum garnet was obtained by the partial chemical method at the low temperature. In this approach, alpha‐alumina nanoparticle, yttrium nitrate, urea, and tetraethyl orthosilicate (TEOS) were used as Al³⁺, Y³⁺, precipitation agent, and both dispersant and phase formation assistant agents, respectively. The results showed that TEOS molecules as a dispersant agent caused the less agglomeration of the alumina‐yttria core‐shell structure with a diameter of 200‐300 nm, as compared to particles obtained without using TEOS molecules. Furthermore, by using 0.5 and 1 wt% of TEOS, the YAG formation temperature was decreased from 1400°C to 1200°C through the liquid‐phase diffusion mechanism. Thus, in this case, the TEOS molecules acted as phase formation assistant agent for the constitution of YAG phases.     

Modelling of heat supply for natural gas pressure reduction station using geothermal energy

In this paper, a series of works are conducted to study the effect of replacing natural gas burning heaters by a ground source heat pumps (GSHPs) to prevent natural gas freezing in the pressure regulating stations. In fact, the pressure drop causes a great temperature drop that can block out the pipeline and it is very crucial to control the phenomenon. Firstly, a conventional heater in the gas pressure drop station of Damavand city is selected as a case study. Then, a shell and tube heat exchanger coupled with GSHP is modelled to replace the conventional heater for eliminating the natural gas consumption in heaters. Finally, consumed energy, costs, and greenhouse gasses emissions are compared with the conventional system. Some main findings from the model show that: (1). Based on the GS2000 software results, the GSHP pipe trench is 601?m which are 7% less than the calculated data. (2). considering different inflation rates (15%-30%), the payback time would change between 4.5 and 7.5 years. (3). Due to the reduction in fossil fuel consumption, the CO₂ emission would be reduced by 47%.     

The Vitamin D Analog Calcipotriol Combined with Aminolevulinate-Mediated Photodynamic Therapy for Human Psoriasis: A Proof-of-Principle Study

We previously showed that select agents (methotrexate or vitamin D), when administered as a preconditioning regimen, are capable of promoting cellular differentiation of epithelial cancer cells while simultaneously enhancing the efficacy of 5-aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT). In solid tumors, pretreatment with vitamin D simultaneously promotes cellular differentiation and leads to selective accumulation of target porphyrins (mainly protoporphyrin IX, PpIX) within diseased tissue. However, questions of whether or not the effects upon cellular differentiation are inexorably linked to PpIX accumulation, and whether these effects might occur in hyperproliferative noncancerous tissues, have remained unanswered. In this paper, we reasoned that psoriasis, a human skin disease in which abnormal cellular proliferation and differentiation play a major role, could serve as a useful model to test the effects of prodifferentiating agents upon PpIX levels in a nonneoplastic setting. In particular, vitamin D, a treatment for psoriasis that restores (i.e., increases) differentiation, might increase PpIX levels in psoriatic lesions and facilitate their responsiveness to ALA-PDT. This concept was tested in a pilot study of seven patients with bilaterally matched psoriatic plaques. A regimen in which calcipotriol 0.005 % ointment was applied for six days prior to ALA-PDT using blue light led to preferential increases in PpIX (ca. 50 %), and reductions in thickness, redness, scaling, and itching in the pretreated plaques. The results suggest that a larger clinical trial is warranted to confirm a role for combination treatments with vitamin D and ALA-PDT for psoriasis.