Impact of Controlling the Site Distribution of Al Atoms on Catalytic Properties in Ferrierite-Type Zeolites

Zeolites with the ferrierite (FER) topology are synthesized using a combination of tetramethylammonium (TMA) cations with differently sized cyclic amines (pyrrolidine (Pyr), hexamethyleneimine (HMI), and 1,4- diazabicyclo[2.2.2]octane (DAB)). Using these organic structure-directing agents (SDAs), low Si/Al ratios and concentrated synthesis mixtures favor the crystallization of FER materials. Increasing the size of the cyclic amine or decreasing the aluminum content leads to the crystallization of other phases or the creation of excessive amounts of connectivity defects. TMA cations play a decisive role in the synthesis of the FER materials, and their presence allows the use of HMI to synthesize FER. Proton MAS NMR is used to quantify the accessibility of pyridine to acid sites in these FER samples, where it is found that the FER + HMI + TMA sample contains only 27% acid sites in the 8-MR channels, whereas FER + Pyr and FER + Pyr + TMA contain 89% and 84%, respectively. The constraint index (CI) test and the carbonylation of dimethyl ether (DME) with carbon monoxide are used as probe reactions to evaluate how changes in the aluminum distribution in these FER samples affect their catalytic behavior. Results show that the use of Pyr as an SDA results in the selective population of acid sites in the 8-MR channels, whereas the use of HMI generates FER zeolites with an increased concentration of acid sites in the 10-MR channels

Development of Competent Mathematical Speech of Students at Technical University

The development of literate speech of students, including mathematics, as one of the areas of communicative component of learning outcomes, is a requirement of higher education standards. The authors have analysed the educational standards for the content of the requirements to the general education of a graduate related to the development of literate speech, as well as the works of domestic and foreign teachers-researchers on the development of mathematical literacy. The literature review and the authors’ own experience of teaching mathematics to engineering students at technical University showed that the ability of students to use logically correct, reasoned and clear oral and written speech is developed insufficiently to apply the mathematical apparatus in their educational and professional activities. The authors have identified the criteria of competent speech and theoretical and methodological conditions of the educational process which enable the ensure the organizational and methodological support of educational process aimed at the development of competent mathematical speech of students. The main applied methods of teaching are advanced self-directed work of students, lecture-discussion, mutual dictation, interchange of tasks, interchange of themes, study of the text fragments, repetition training-game, etc. The effectiveness of educational activities is achieved through the use of active and interactive forms of teaching. The prepared organizational and methodological support of teaching, the systemic educational work allow students to improve their speech skills and skills of active use of mathematical language as a universal language of science, to develop logical, algorithmic and mathematical thinking, the ability to apply methods of mathematical analysis and modeling, theoretical and experimental research in solving professional problems

Some peculiarities of time-frequency dynamics of spike-wave discharges in humans and rats

Contains fulltext : 56663.pdf (publisher's version ) (Closed access)Objective - Time–frequency dynamics of spike–wave discharges (SWDs) were investigated in patients with absence seizures and in WAG/Rij rats, a genetic model of absence epilepsy using a specially developed wavelet transform. Methods - Two types of SWDs were analyzed in both species: the most frequently occurring discharges (of minimal 3.6–4.0 s or more) and shorter ones recorded from various cortical regions. Results - The more prolonged discharges had two phases: during the initial part (from tenth of seconds to 1 s) of the seizure the frequency decreased quickly from 5 to 3.5 Hz in patients and from about 15 to 10 Hz in rats. A slower frequency decrease with periodical fluctuations was observed in both species during the second part of the discharge: the frequency decreased towards the end of the discharge to 3 Hz in patients and to 6–7 Hz in rats. The frequency of the short discharges decreased fast during the whole discharge: from 5 to 2–2.5 Hz and from about 15 to 5 Hz in patients and rats, respectively. Conclusions - Comparison of data obtained in patients with typical absence epilepsy and WAG/Rij rats with genetic absence epilepsy revealed that the time–frequency dynamics of SWDs had similar properties but in a different frequency range. Significance - The study of time–frequency dynamics using this specially developed wavelet transform revealed two different types of SWDs, which most likely represent different dynamics in the cortico-thalamo-cortical loop during shorter and more prolonged discharges.8 p

Investigation of Phase Shifts Using AUC Diagrams: Application to Differential Diagnosis of Parkinson’s Disease and Essential Tremor

This study was motivated by the well-known problem of the differential diagnosis of Parkinson’s disease and essential tremor using the phase shift between the tremor signals in the antagonist muscles of patients. Different phase shifts are typical for different diseases; however, it remains unclear how this parameter can be used for clinical diagnosis. Neurophysiological papers have reported different estimations of the accuracy of this parameter, which varies from insufficient to 100%. To address this issue, we developed special types of area under the ROC curve (AUC) diagrams and used them to analyze the phase shift. Different phase estimations, including the Hilbert instantaneous phase and the cross-wavelet spectrum mean phase, were applied. The results of the investigation of the clinical data revealed several regularities with opposite directions in the phase shift of the electromyographic signals in patients with Parkinson’s disease and essential tremor. The detected regularities provide insights into the contradictory results reported in the literature. Moreover, the developed AUC diagrams show the potential for the investigation of neurodegenerative diseases related to the hyperkinetic movements of the extremities and the creation of high-accuracy methods of clinical diagnosis

In vitro production of Indian citrus ringspot virus (ICRSV) free kinnow plants employing phytotherapy coupled with shoot tip grafting

This paper reports the elimination of Indian citrus ringspot virus (ICRSV) from “kinnow” (Citrus nobilis Lour × Citrus deliciosa Tenora) employing phytotherapy coupled with shoot tip grafting under in vitro conditions. Nodal segments from infected mother plant (indexed by indirect enzyme-linked immunosorbent assay [ELISA] and reverse transcriptase PCR [RT-PCR]) were cultured on Murashige and Skoog medium containing 2iP (1 mg/l or 4.9 μM) and malt extract (800 mg/l) along with different concentrations of aqueous extracts from leaves of Azadirachta indica (Neem), Sorghum vulgare (Jowar), and roots of Boerhaavia diffusa (Punarnava). Shoot tips were excised from the nodal sprouts and grafted on to rough lemon (Citrus jambhiri) under aseptic conditions. Maximum effect (50% virus elimination) was seen for aqueous leaf extracts of A. indica followed by B. diffusa root extract (42.86%) and S. vulgare leaf extract (31.58%). Plants/plantlets were considered virus-free only when showing negative reactions by both indirect ELISA and RT-PCR

Combined Experimental and Theoretical Investigations of Heterogeneous Dual Cation Sites in Cu,M-FER Zeolites

Carbon monoxide is frequently used as a probe molecule for characterization of adsorption sites in zeolites by means of infrared (IR) spectroscopy. IR spectra of carbonyl species in zeolites are usually understood within a concept of CO adsorption on a single cation site. This concept, however, is not sufficient in microporous materials when the concentration of cationic sites increases. Adsorption complexes formed on homogeneous dual cation sites were recently described (J. Phys. Chem. B 2006, 110, 22542) based on a combination of experimental and theoretical investigations. The concept of dual cation sites is extended for the situation where CO is strongly bound on the Cu+ cation and it also interacts with the extra-framework alkali-metal cation. The existence and properties of theCOadsorption complexes on such heterogeneous dual cation sites are discussed for Cu,M-FER zeolites (M =H, Na, K, Cs) having various compositions. Based on a good agreement between theoretical (periodic density functional theory) and experimental (IR, microcalorimetry, TPD) results, the interpretation of some IR features is offered.Bulanek, R.; Frolich, K.; Cicmanec, P.; Nachtigallova, D.; Pulido Junquera, MA.; Nachtigall, P. (2011). Combined Experimental and Theoretical Investigations of Heterogeneous Dual Cation Sites in Cu,M-FER Zeolites. Journal of Physical Chemistry C. 115(27):13312-13321. doi:10.1021/jp200293yS13312133211152