Non-contact method for measurement of the microwave conductivity of graphene

We report a non-contact method for conductivity and sheet resistance measurements of graphene samples using a high Q microwave dielectric resonator perturbation technique, with the aim of fast and accurate measurement of microwave conductivity and sheet resistance of monolayer and few layers graphene samples. The dynamic range of the microwave conductivity measurements makes this technique sensitive to a wide variety of imperfections and impurities and can provide a rapid non-contacting characterisation method. Typically the graphene samples are supported on a low-loss dielectric substrate, such as quartz, sapphire or SiC. This substrate is suspended in the near-field region of a small high Q sapphire puck microwave resonator. The presence of the graphene perturbs both centre frequency and Q value of the microwave resonator. The measured data may be interpreted in terms of the real and imaginary components of the permittivity, and by calculation, the conductivity and sheet resistance of the graphene. The method has great sensitivity and dynamic range. Results are reported for graphene samples grown by three different methods: reduced graphene oxide (GO), chemical vapour deposition (CVD) and graphene grown epitaxially on SiC. The latter method produces much higher conductivity values than the others.Comment: 8 pages, 2 figures and 2 table

Nature behavioral responses, lipid profile and state of cardiovascular system in lead intoxication modelling on the background of hyperlipidemia in albino rats

The article describes the comparative study of the effect of lead intoxication in healthy animals and in terms of modelled hyperlipidemic condition on lipid metabolism, ECG performance, behavior in the test of the extrapolation of deliverance. The study was performed on 40 albino outbred adult male rats. Modeling hyperlipidemic condition was carried out daily by feeding natural unsalted fat at the rate of 8 grams per animal for 16 days. Lead intoxication was created after the atherogenic diet by adding lead acetate into drinking water in a dose of 50 mg/kg of body weight for 4 weeks. To investigate the lipid metabolism was measured in serum total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol. In the test of extrapolation deliverance 70 % of animals with lead intoxication on the lipid load background did not cope with the task versus 40 % of albino rats in the group with lead acetate exposure alone. All control animals successfully solved the problem of the deliverance test. The deterioration of the functioning of the cardiovascular system of rats with lead poisoning on the background of atherogenic diet was manifested by elongation of intraventricular conduction intervals on an electrocardiogram as compared with animals with lead intoxication alone. Disorders of lipid metabolism were manifested by increased levels of LDL cholesterol in rats with lead intoxication on the background of hyperlipidemia to 0.86 (0.69-1.14) mmol/l compared with the value of 0.67 (0.58-0.79) mmol/l in animals with lead intoxication

Affine spherical homogeneous spaces with good quotient by a maximal unipotent subgroup

For an affine spherical homogeneous space G/H of a connected semisimple algebraic group G, we consider the factorization morphism by the action on G/H of a maximal unipotent subgroup of G. We prove that this morphism is equidimensional if and only if the weight semigroup of G/H satisfies some simple condition.Comment: v2: title and abstract changed; v3: 16 pages, minor correction

Pillar[5]arenes bearing amide and carboxylic groups as synthetic receptors for alkali metal ions

© ISUCT Publishing. Pillar[5]arenes bearing amide and carboxylic groups have demonstrated recognition performance for some representative alkali metal ions including Li + , Na + , K + and Cs + in series cations of s- and d-metals compared to pillar[5] arenes with hydroxyl, methoxy and acetone fragments. Their complexation abilities toward these cations were evaluated by UV–Vis technique. The complexation results revealed that pillar[5] arene, containing glicylglicyne groups, were the most efficient cation receptors for Li + , Na + , K + and Cs + over other synthesized and studied pillar[5]arenes. Introduction of long glycylglycide fragments into macrocycle structure allowed to increase the association constant logarithm in the case of Li + by 2 orders. In addition, in the set of macrocycles, incorporation of the additional amide fragments and carboxyl group into macrocycle structure leads to increasing the binding efficiency with alkali metal cations

Polyammonium derivatives of (thia)calix[4]arene: Synthesis and interaction with nucleic acids

© 2015 Nova Science Publishers, Inc. Targeted delivery of polynucleic acids in cells (transfection) for therapeutic purposesis limited by a number of obstacles, starting from the cell membrane to the geneexpression. To overcome the cell barriers, the use of gene carriers - viral and non-viralvectors are employed. One of the current approaches employed in the development ofsynthetic nonviral vectors is the functionalization of easily accessible molecularplatforms with receptor groups (amino, ammonium or guanidinium groups), capable ofinteracting with nucleic acids.In this chapter, we examine recent advances in the design and development ofsynthetic vectors, and the principles underlying their interactions with nucleic acids. Thefocus will be on recent advances in the design and synthesis of potential transfectionagents based on the (thia)calixarene platform functionalized with different polyaminofragments differing in the number of amino groups, the length of their alkyl linker chainsand the present or absent of hydroxy groups. The interaction of functionalized(thia)calixarene derivatives with DNA will also be discussed

Dream in a mode of biological rhythms of student's youth

The healthy lifestyle of any person includes such important concepts as keeping of a mode of work and rest. For activity of a young organism importance of a dream represents special value. However in student's life as all of us know, it is very difficult to keep a constant sleep patternЗдоровый образ жизни любого человека включает такие немаловажные понятия как соблюдение режима труда и отдыха. Для жизнедеятельности молодого организма важность сна представляет особое значение. Однако, в студенческой жизни, как мы все знаем, очень трудно соблюдать постоянный режим сн

Monoaminophosphorylated pillar[5]arenes as hosts for alkaneamines

© The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.For the first time, monofunctionalized pillar[5]arenes containing a 1-aminophosphonate fragment have been obtained and characterized. As shown by NMR spectroscopy, the replacement of the amino groups by 1-aminophosphonate units in the macrocycle structure allows switching of “self-assembling-host-guest complexation” properties of the monofunctionalized pillar[5]arenes. Thus, new synthesized aminophosphonated pillar[5]arenes form host-guest complexes with aliphatic amines contrary to monoamine macrocycles that tend to self-assemble