Semiempirical Study of Intramolecular Hyclrogen Bond in 6-Hydroxy-2-formylfulvene and 9-Hydroxyphenalenone

It is shown that semiempirical MINDO/3, MNDO and AMI methods are very useful in discussing intramolecular hydrogen . bonding in sizeable systems. The present results indicate that intramolecular H-bonds in 6-hydroxy-2-formylfulvene and 9-hydroxyphenalenone are asymmetric, in fuU accordance with ESCA observations and DQCC measurements. The former molecule should exhibit a stronger H-bond. On the other hand, the barrier height for proton tunnelling is higher in the latter compound. Relative stabilities of various species are interpreted by employing the energy partitioning technique

Molecular Second Moments and Diamagnetic Susceptibilities. Reparametrization of the Independent Atom Model Formulas

The independent atom model (IAM) is applied to the calculation of molecular second moments and diamagnetic susceptibilities. The earlier formulas are generalized and better agrement with experimental data and ab initio results is achieved

A Semiempirical Study of Intramolecular Hydrogen Bonding in Some Naphthazarin Derivatives

Structural and energetic properties of some derivatives of naphthazarin are considered by the semiempirical AMI method. It is shown that these systems, possessing intramolecular hydrogen bonds, are qualitatively well described at the AMI level of theory. This conclusion is supported by a good qualitative agreement with available experimental data. The strength of the intramolecular hydrogen bond is briefly discussed. It appears that their energies are roughly additive

Rates of Oxidation of Some Bicyclic Alcohols with Silver Carbonate on Celite

It is well known that silver carbonate is a powerful agent for the oxidation of both primary and secondary alcohols1\u272 Recently Fetizon introduced a convenient modification of this procedure by using silver carbonate precipitated on celite3-

Electrocatalysis of small organic molecules oxidation on platinum and palladium electrodes modified by palladium, rhodium and ruthenium nanoislands-importance for fuel cells application.

Kao odgovor rastućim energetskim potrebama modernog društva i potrebi za rešavanjem ekoloških problema, naučna i tehnološka istraživanja su fokusirana ka pronalaženju čistih i efikasnih izvora energije u cilju smanjenja emisije CO2 koje potiče od sagorevanja fosilnih goriva i izbegavanju eventualne energetske krize. Shodno tome, javlja se sve veće interesovanje ka razvoju novih, jeftinijih i ekoloških sistema za konverziju i skladištenje energije. Od svih sistema za konverziju energije najviše obećavaju gorivne ćelije koje kao gorivo koriste male organske molekule kao što su vodonik, metanol i etanol u kojima se prilično efikasno vrši direktna konverzija hemijske u električnu energiju uz vrlo nisku emisiju zagađivača. Gorivne ćelije koje koriste alkohol kao gorivo (DAFCs – Direct Alcohol Fuel Cells) kao izvor energije su naročito pogodne za korišćenje, kako u prevoznim sredstvima, tako i u malim elektronskim uređajima, zbog njihovog relatvno brzog starta i niske radne temperature. Uprkos obimnim istraživanjima, široka upotreba alkoholnih gorivnih ćelija još uvek je ograničena zbog njihove cene, relativno niske energije kao i nezadovoljavajuće gustine snage. U cilju rešavanja ovih problema, istraživanja su usmerena ka boljem razumevanju mehanizama elektrohemijskih reakcija koje se dešavaju u gorivnim ćelijama i razvoju visoko aktivnih elektrodnih katalizatora da bi se postigla bolja efikasnost, a samim tim i smanjenje cene. U ovom proučavanju, ispitivane su reakcije elektrooksidacije metanola i etanola u alkalnoj sredini na bimetalnim elektrodama, dobijenim spontanim deponovanjem nanoostrva paladijuma, rodijuma i rutenijuma uz pokrivenost manju od monosloja na površinama polikristalnih elektroda platine i paladijuma. Ex-situ karakterizacija dobijenih Pd/Pt(poly), Rh/Pd(poly) i Ru/Pd(poly) nanostruktura je vršena mikroskopijom atomskih sila (AFM), elipsometrijskom spektroskopijom i rendgenskom fotoelektronskom sprektroskopijom (XPS). In-situ karakterizacija dobijenih elektroda kao i proučavanje reakcije elektrooksidacije metanola i etanola vršene su cikličnom voltametrijom u 0,1 M KOH-u. Bimetalne površine modifikovanih elektroda su pokazale bolju katalitičku aktivnost za reakcije oksidacije metanola i etanola u alkalnoj sredini...In response to the energy needs of modern society and emerging ecological concerns, scientific and technological researches have focused on the development of clean, efficient power sources to diminish CO2 emission coming from combustion of fuels and to avoid energy crisis. Consequently, development of novel, low-cost, and environment friendly energy conversion and storage systems has raised significant interest. Among various energy conversion and storage systems, one of the most encouraging is fuel cells using small organic molecules such as methanol and ethanol since they convert chemical energy directly into electrical energy with high efficiency and low pollutant emissions. Direct alcohol fuel cells (DAFCs) are an ideal fuel cell system for applications in electric vehicles and electronic portable devices due to their relatively quick start-up and low operating temperature. Despite extensive research, the wide commercial use of DAFCs is hampered by their high cost, relatively low energy and power densities. In order to address these problems, researches are focused to better understanding of the mechanism of electrochemical reactions taking place in fuel cells and development of highly active electrode catalysts to attain high efficiency of DAFCs, and subsequently lowering the cost. In this study, bimetallic electrodes prepared by Pd, Rh and Ru nanoislands spontaneously deposited on polycrystalline platinum, Pt(poly), and polycrystalline palladium, Pd(poly), at submonolayer coverage were explored for methanol and ethanol oxidation in alkaline media. Characterization of obtained Pd/Pt(poly), Rh/Pd(poly) and Ru/Pd(poly) nanostructures was performed ex situ by AFM imaging, spectroscopic ellipsometry and by X-ray photoelectron spectroscopy. In situ characterization of the obtained electrodes and subsequent methanol and ethanol oxidation measurements were performed by cyclic voltammetry in 0,1 M KOH. Bimetallic surfaces of modified electrodes exhibited the highest catalytic activity for methanol and ethanol oxidation in alkaline media..

Energy consumption in the electrolytic evolution of hydrogen with iron-nickel electrodes

The possibilities to reduce energy consumption in the electrolytic hydrogen production using ionic activators added into an alkaline electrolyte have been investigated. Two cathode/anode systems, Fe/Ni and Ni/Fe were investigated. We have found that some activators, like tris-(ethylenediamine)Co(III) chloride complex in combination with the sodium molybdate can reduce energy needs per mass unit of hydrogen produced for more than ten percent in all investigated systems compared to those of non-activated electrolytes. Additionally, iron exhibits some special properties in this view.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Genetic and epigenomic modifiers of diabetic neuropathy

Diabetic neuropathy (DN), the most common chronic and progressive complication of diabetes mellitus (DM), strongly affects patients’ quality of life. DN could be present as peripheral, autonomous or, clinically also relevant, uremic neuropathy. The etiopathogenesis of DN is multifactorial, and genetic components play a role both in its occurrence and clinical course. A number of gene polymorphisms in candidate genes have been assessed as susceptibility factors for DN, and most of them are linked to mechanisms such as reactive oxygen species production, neurovascular impairments and modified protein glycosylation, as well as immunomodulation and inflammation. Different epigenomic mechanisms such as DNA methylation, histone modifications and non-coding RNA action have been studied in DN, which also underline the importance of “metabolic memory” in DN appearance and progression. In this review, we summarize most of the relevant data in the field of genetics and epigenomics of DN, hoping they will become significant for diagnosis, therapy and prevention of DN

Deficijencija B12 vitamina kod deteta majke na veganskoj ishrani

Vitamin B12 deficiency usually occurs in exclusively breastfed infants whose mothers have pernicious anaemia or are vegetarian. Early treatment of vitamin B12 deficiency in infants can prevent potentially neurologic sequelae. A male child aged 13 months has been hospitalized due to failure to thrive, feeding problems, pallor, weakness and hypotonia. During the pregnancy mother did not eat meat and during lactation she also excluded eggs and milk. The child was exclusively breastfed. Laboratory investigations showed a haemoglobin level of 3.5 g/dL, haematocrit 10%, red blood cell count of 0.99 × 1012/L, white blood cell count of 4.23 × 109 /L and platelet count of 55 × 109 /L. Vitamin B12 level was low. A bone marrow aspiration finding was consistent with megaloblastic anaemia. The magnetic resonance imaging showed brain atrophy. Vitamin B12 in a dose of 10µg per kg was applied intramuscularly daily for 2 weeks, then once weekly. Three days after initiating B12 vitamin therapy there was an improvement in the blood count with the gradual improvement of neurological state. Vitamin B12 deficiency is a treatable cause of pancytopenia and neurological dysfunction in children and should be considered as differential diagnosis in an infant with neurological symptoms.Deficijencija B12 vitamina se obično javlja kod odojčadi koja su na prirodnoj ishrani a čije majke imaju pernicioznu anemiju ili su vegetarijanci. Pravovremeno lečenje deficijencije B12 vitamina kod odojčadi može da prevenira potencijalne neurološke posledice. Malo muško dete uzrasta 13 meseci je hospitalizovano zbog nenapredovanja, problema sa hranjenjem, bledila, slabosti i hipotonije.Tokom trudnoće majka nije jela meso dok je tokom dojenja iz ishrane isključila i jaja i mleko. Dete je isključivo dojeno. U laboratorijskim nalazima nivo hemoglobina je iznosio 3,5 g/dl, hematokrit 10%, broj eritrocita je bio 0.99×1012/L, broj leukocita 4.23×109 /L i broj trombocita 55×109 /L. Nivo B12 vitamina je bio snižen. Nalaz biopsije kostne srži ukazivao je na megaloblastnu anemiju. Na magnetnoj rezonanci endokranijuma viđena je atrofija mozga. Vitamin B12 u dozi od 10 mikrograma/kg primenjen je intramuskularno svakodnevno tokom 2 nedelje, potom jednom nedeljno.Tri dana od započinjanja terapije zabeleženo je poboljšanje hematoloških vrednosti uz postepeno poboljšanje neurološkog statusa. Deficijencija B12 vitamina je uzrok pancitopenije i neurološke disfuncije kod dece koju je moguće lečiti. Kod odojčeta sa neurološkim simptomima ova deficijencija treba da bude razmotrena kao diferencijalna dijagnoza

Environmental Education in Serbian Primary Schools: Challenges and Changes in Curriculum, Pedagogy, and Teacher Training

The protection of human health and the preservation of the environment are topics that form anintegral part of the primary school curriculum in Serbia. However, research studies have shown thatstudents do not have enough knowledge to contribute to the development of a healthy lifestyle andenvironmental awareness. The latest changes in school policy and curricula confirm that the relevanceof environmental education has been recognized, but changes in school practice are yet to come. Thisarticle discusses the challenges encountered in the implementation of the intended curriculum andoffers suggestions for changes to the curriculum, pedagogy, and teacher training in order to enhanceenvironmental educationThis is the peer-reviewd version of the artivle: Stanišić, Jelena, и Slavica Maksić. 2014. „Environmental Education in Serbian Primary Schools: Challenges and Changes in Curriculum, Pedagogy, and Teacher Training“. Journal of Environmental Education 45(2):118–31. doi: 10.1080/00958964.2013.829019.Related to published version: [ http://ipir.ipisr.org.rs/handle/123456789/240