Plant communities and reproductive phenology in mountainous regions of northern Libya

Within the semi-desert landscape of northern Libya, two sub-humid escarpments occur: Al-Akhdar in the east and Nafusa (Jabal Al-Gharbi) in the west. This study compares plant communities in the two regions, which are along an elevation gradient, in terms of species composition and diversity, frequency of different Raunkiaer life forms, and reproductive phenology. The two regions differed in species composition and life-form frequency between regions and between elevation zones within each region. Patterns were associated with the lower rainfall and lower moisture-holding capacity of soils at Nafusa, resulting in more xeric conditions. Only 13% of species were shared between the two regional landscapes. Species diversity, life-form frequency, and duration of the flowering-fruiting phenophase were all affected by elevation above sea level. The duration of flowering and fruiting in spring and fall was associated with environmental conditions, although there were different thresholds in the two regions. There was both a spring and fall episode of flowering at Nafusa, but only spring flowering at Al-Akhdar. It is anticipated that there will be a gradual shift of plant communities to higher elevations and loss of certain sensitive species in response to ongoing climate change.

Spectroscopic and photometric studies of a candidate pulsating star in an eclipsing binary:V948 Her

Eclipsing binary stars with a pulsating component are powerful tools that allow us to probe the stellar interior structure and the evolutionary statuses with a good accuracy. Therefore, in this study, spectroscopic and photometric examinations of an eclipsing binary system V948 Her are presented. The primary component of the system is classified to be a candidate 3 Scuti variable in the literature. The fundamental stellar, atmospheric and orbital parameters, and the surface abundance of the star were determined and the pulsation behaviour was investigated in this study. The orbital parameters were derived by the analysis of radial velocity and SuperWASP light curves. The spectral classification was found to be F2V. The initial atmospheric parameters of the primary component were derived by analysis of the spectral energy distribution and hydrogen lines. The final atmospheric parameters and chemical abundances of the primary component were obtained by using the method of spectrum synthesis. As a result, the final atmospheric parameters were determined as Teff= 7100±200 K, log 9= 4.34±0.1 cgs and ζ = 2.2 4± 0.2 km s^-1. The surface abundance was found to be similar to solar. The fundamental stellar parameters of both components were also obtained to be M = 1.722 4±0.123, 0.762 4± 0.020 Me, R = 1.655 4± 0.034,M,R= 0.689 ± 0.016 R for primary and secondary components, respectively. The pulsation characteristic of the primary component was examined using SuperWASP data and the pulsation period was found to be ~0.038 d. The position of the primary pulsating component was also obtained inside the instability strip of δ Sct stars. The primary component of V948 Her was defined to be a Sct variable.

SYNTHESIS,CHARACTERIZATION,THERMAL DEGRADATION AND ELECTROCHEMICAL PROPERTIES OF OLIGO-4-m-TOLYLAZOMETHINEPHENOL

The oxidative polycondensation reaction conditions of 4-m-tolylazomethinephenol （4-TAMP） in the presence of air O2 and NaOCl as oxidants were studied in an aqueous alkaline medium between 50 and 90℃. The structures of the obtained monomer and oligomer were confirmed by FT-IR, UV-Vis, ^1H- and ^13C-NMR and elemental analysis techniques. The physical characterization was made by TG-DTA, size exclusion chromatography （SEC） and solubility tests. At the optimum reaction conditions, the yield of oligo-4-m-tolylazomethinephenol （O-4-TAMP） was found to be 62.50% （for air O2 oxidant） and 90.0% （for NaOCl oxidant）, respectively. According to the SEC analysis, the number-average molecular weight （Mn）, weight-average molecular weight （Mw） and polydispersity index （PDI） values of O-4-TAMP were found to be 2310, 2610 g tool 1 and 1. 13, respectively, using air O2, and 1390, 1710 g mol^-1 and 1.23, using NaOCl, respectively. According to TG-DTA analyses, O-4-TAMP was more stable than 4-TAMP against thermal decomposition. The weight losses of 4-TAMP and O-4-TAMP were found to be 68% and 58% at 1000℃. Electrical conductivity of the O-4-TAMP was measured, showing that the polymer is a typical semiconductor. Electrochemically, the highest occupied molecular orbital （HOMO）, the lowest unoccupied molecular orbital （LUMO） and electrochemical energy gaps （E＇g） for 4-TAMP are -5.96, -3.22 and 2.74 eV, respectively. The HOMO, LUMO and （E＇g） for O-4-TAMP are -5.78, -3.44 and 2.34 eV, respectively. According to UV-Vis measurements, optical band gaps （Eg） of 4-TAMP and O-4-TAMP were found to be 3.45 and 3. 1 0 eV, respectively.

Determination of ^(210)Po and ^(210)Pb depositions in lichen and soil samples collected from K?prüba??-Manisa,Turkey

üIn this study, we aimed to determine the accumulations of ^(210) Po and ^(210) Pb in soil and lichen samples in K? prü bas??. The K? prü bas?? district is home to the largest uranium deposits in Turkey. To date, there has been no study recorded in the literature related to ^(210) Po and ^(210) Pb depositions in lichens in K? prü bas??. Six different lichen species(Cladonia convoluta, Parmelina tiliacea, Physcia stellaris, Pleurosticta acetabulum, Xanthoparmelia conspersa, and Xanthoria parietina) as well as soil samples were collected from seven sampling locations around K? prü bas??. Lichens were used as biomonitors for ^(210) Po and ^(210) Pb deposition. The ^(210) Po and ^(210) Pb activity concentrations were measured in all the samples by alpha spectrometry. The activity concentrations in the lichen samples ranged from 64 to 577 Bq kg^(-1) with an average of 266 Bq kg^(-1) for ^(210) Po and from 78 to 565 Bq kg^(-1) with an average of 333 Bq kg^(-1) for ^(210) Pb. The activity ratios of ^(210) Po/ ^(210) Pb ranged from 0.80 to 1.99. In the lichen species,the mean ^(210) Po activity values varied from 154 Bq kg^(-1) in Pleurosticta acetabulum to 390 Bq kg^(-1) in Xanthoparmelia conspersa. The range of the mean ^(210) Pb activity was between 153 Bq kg^(-1) in Cladonia convoluta and 378 Bq kg^(-1) in Parmelina tiliacea. In the soil samples, ^(210) Po and ^(210) Pb activity concentrations were ranged from14 to 1268 Bq kg^(-1) and from 19 to 1113 Bq kg^(-1),respectively. While the values of ^(210) Po and ^(210) Pb measured in the lichen samples are comparable with those of the literature, the results of ^(210) Po and ^(210) Pb in the soil taken from the uranium mine are higher than the results of the literature studies.

Periodicity and Solution of Rational Recurrence Relation of Order Six

Difference equations or discrete dynamical systems is diverse field whose impact almost every branch of pure and ap- plied mathematics. Every dynamical system an+1=f(an) determines a difference equation and vise versa. We ob-tain in this paper the solution and periodicity of the following difference equation. xn+1=(xnxn-2xn-4)/(xn-1xn-3xn-5, (1) n=0,1,... where the initial conditions x-5,x-4,x-3,x-2,x-1 and x0 are arbitrary real numbers with x-1,x-3 and x-5 not equal to be zero. On the other hand, we will study the local stability of the solutions of Equation (1). Moreover, we give graphically the behavior of some numerical examples for this difference equation with some initial conditions.

Electrical and dielectric characterization of Au/ZnO/n-Si device depending frequency and voltage

Au/Zn O/n-type Si device is obtained using atomic layer deposition（ALD） for Zn O layer, and some main electrical parameters are investigated, such as surface/interface state（Nss）, barrier height（Φb）, series resistance（Rs）, donor concentration（Nd）, and dielectric characterization depending on frequency or voltage. These parameters are acquired by use of impedance spectroscopy measurements at frequencies ranging from 10 k Hz to 1 MHz and the direct current（DC） bias voltages in a range from-2 V to ＋2 V at room temperature are used. The main electrical parameters and dielectric parameters,such as dielectric constant（ε＂）, dielectric loss（ε＂）, loss tangent（tan δ）, the real and imaginary parts of electric modulus（M and M）, and alternating current（AC） electrical conductivity（σ） are affected by changing voltage and frequency. The characterizations show that some main electrical parameters usually decrease with increasing frequency because charge carriers at surface states have not enough time to fallow an external AC signal at high frequencies, and all dielectric parameters strongly depend on the voltage and frequency especially in the depletion and accumulation regions. Consequently, it can be concluded that interfacial polarization and interface charges can easily follow AC signal at low frequencies.

Biosorption of Cadmium Ions by Unmodified, Microwave and Ultrasound Modified Brewery and Pure Strain Yeast Biomass

The present study investigates the biosorption of cadmium ions from aqueous solution onto unmodified, ultrasound and microwave treated cells of Saccharomyces cerevisiae. FTIR analysis was conducted to characterize the biosorbent. Equilibrium and kinetic studies of unmodified RBW (residual brewery waste) cell yeast and DSM 1333 (pure strain) were conducted by considering the effect of initial cadmium ions concentration. Results showed that the ultrasound and microwave treatments decrease the heavy metal uptake compared with the unmodified biomass. Langmuir and Freundlich isotherm models on both unmodified yeast cell types were used to analyze the equilibrium data. It was found that the Langmuir isotherm and pseudo-second-order kinetics models describe better the cadmium ions removal process.

Design and Analysis of an OSA-BR MAC Protocol for Cognitive Radio Ad Hoc Networks

Cognitive Radio (CR) is a new communication network paradigm introduced to solve the problems of spectrum scarcity and inefficient spectrum usage. Basically, it allows the Secondary Users (SUs) to utilize the Licensed Channels (LCs) of the Primary Users (PUs) in an opportunistic manner without causing any harmful interference to the PUs. However, there are many challenges associated with cognitive radio networks, such as the CR Medium Access Control (CR-MAC) protocols. An important issue for CR-MAC protocols is to identify whether the spectrum is licensed or unlicensed. In addition, the sudden appearance of the PU is the most important feature of the distributed CR-MAC protocols. In this paper, a multichannel CR-MAC protocol, which reacts efficiently to the appearance of the PUs, is developed. The proposed protocol is named Opportunistic Spectrum Access with backup channel and Buffered data with Resume (OSA-BR). The OSA-BR is an unaided rendezvous, asynchronous, and contention-based MAC protocol. The proposed protocol operates in heterogeneous environment, where the SUs utilize both LCs and unlicensed channel (ULs) and the activities of the Classical Users (CUs) are taken into consideration. In addition, the concept of the backup channel and the buffer with resume are introduced. The simulation results show that OSA-BR accomplishes 35% throughput gain over the SWITCH protocol and 55% over other CR-MAC protocols.

Electrical Characteristics of Co/n-Si Schottky Barrier Diodes Using I -- V and C -- V Measurements

Electrical characteristics of Co/n-Si Schottky barrier diodes are analysed by current- voltage （I- V） and capacitancevoltage （C- V） techniques at room temperature. The electronic parameters such as ideality factor, barrier height and average series resistance are determined. The barrier height 0. 76 eV obtained from the C - V measurements is higher than that of the value 0. 70 eV obtained from the I - V measurements. The series resistance Rs and the ideality factor n are determined from the d ln（ I） /dV plot and are found to be 193.62 Ω and 1.34, respectively. The barrier height and the Rs value are calculated from the H（I） - I plot and are found to be 0.71 eV and 205.95Ω. Furthermore, the energy distribution of the interface state density is determined from the forward bias I - V characteristics by taking into account the bias dependence of the effective barrier height. The interface state density Nss ranges from 6.484×10^11 cm^-2eV^-1 in （Ec - 0.446） eV to 2.801×10^10 cm^-2eV^-1 in （Ec - 0.631） eV, of the Co/n-Si Schottky barrier diode. The results show the presence of a thin interracial layer between the metal and the semiconductor.

Effects of magnetohydrodynamic flow past a vertical plate with variable surface temperature

An analysis is performed to study the magnetohydrodynamic flow of an electrically conducting, viscous incompressible fluid past a semi-infinite vertical plate with variable surface temperature under the action of transversely applied magnetic field. The heat due to viscous dissipation and the induced magnetic field are assumed to be negligible. The dimensionless governing equations are unsteady, two-dimensional, coupled and non-linear governing equations. It is found that the magnetic field parameter has a retarding effect on the velocities of air and water.

Note on a New Construction of Kantorovich Form q-Bernstein Operators Related to Shape Parameter λ

The main purpose of this paper is to introduce some approximation properties of a Kantorovich kind q-Bernstein operators related to B′ezier basis functions with shape parameterλ∈[−1,1].Firstly,we compute some basic results such as moments and central moments,and derive the Korovkin type approximation theorem for these operators.Next,we estimate the order of convergence in terms of the usual modulus of continuity,for the functions belong to Lipschitz-type class and Peetre’s K-functional,respectively.Lastly,with the aid of Maple software,we present the comparison of the convergence of these newly defined operators to the certain function with some graphical illustrations and error estimation table.

Annual effective dose values from^137Cs activity concentrations in soils of Manisa,Turkey

In this study,the activity concentrations of the fallout radionuclide ^(137(Cs in 150 soil samples collected from 13 districts of Manisa Province were determined using a gamma ray spectrometer with a Na I(Tl) detector.The health risks to people resulting from external exposure were evaluated by estimating the outdoor absorbed gamma dose rate and annual effective dose rate(outdoor and indoor).The activity concentration of ^(137)Cs varied from 3.6 ± 2.0 to 124.1 ± 11.0 Bq kg^(-1),with an average value of43.3 Bq kg^(-1).The average values of the outdoor absorbed gamma dose rate and annual effective dose(outdoor plus indoor) were found to be 1.3 n Gy h^(-1),and 8.0 μSv y^(-1),(6.38 + 1.59 μSv y^(-1)),respectively.The results were compared with internationally recommended values.

The evolutionary status of chemically peculiar eclipsing binary star DV Boo

Eclipsing binary systems are unique stellar objects to examine and understand stellar evolution and formation.Thanks to these systems,the fundamental stellar parameters(mass,radius)can be obtained very precisely.The existence of metallic-line(Am)stars in binaries is noticeably common.However,the known number of Am stars in eclipsing binaries is less.The Am stars in eclipsing binaries are extremely useful to deeply investigate the properties of Am stars,as eclipsing binaries are the only tool to directly derive the fundamental stellar parameters.Additionally,the atmospheric parameters and metallicities of such binary components could be obtained by a detailed spectroscopic study.Therefore,in this study,we present a comprehensive photometric and spectroscopic analysis of the eclipsing binary system DV Boo which has a possible Am component.The fundamental stellar parameters were determined by the analysis of radial velocity and photometric light curves.The atmospheric parameters of both binary components of DV Boo were derived considering the disentangled spectra.The chemical abundance analysis was carried out as well.As a result,we showed that the primary component exhibits a typical Am star chemical abundance distribution.The fundamental stellar parameters of the binary components were also obtained with an accuracy of<1%for masses and<3%for radii.The evolutionary status of DV Boo was examined utilizing the precisely obtained stellar parameters.The age of the system was found to be 1.00±0.08 Gyr.

Trace Elements in the Soil-Plant Systems of Copper Mine Areas-A Case Study From Murgul Copper Mine From the Black Sea Region of Turkey

This study presents a case study on the heavy metal analysis of soil and plant samples around the Murgul copper mine,one of the first and most important mining areas in Turkey.An attempt has been made to investigate the status of trace elements like Al^(3+),Fe^(2+),Cu^(2+),Zn^(2+),Pb^(2+),Ni^(2+),Co^(2+)and Cd^(2+)in soils and plants.The sampling localities were taken from 500 m,600 m,and 1000 m altitudes around the factory and at 1400 m in the forest zone.The aboveground parts and foliage ash of Silene compacta,Tussilago farfara,Smilax excelsa,Rhododendron ponticum,R.luteum,and herbal mix were analysed.The results of analysis have revealed the minimum and maximum concentrations measured in the plants as follows;aluminium(20-8985 mg kg^(-1)),cadmium(0.0-0.5 mg kg^(-1)),cobalt(0.0-5.5 mg kg^(-1)),copper(0.0-347.5 mg kg^(-1)),iron(25-9320 mg kg^(-1)),lead(2-51 mg kg^(-1)),nickel(1.5-16.5 mg kg^(-1)),and zinc(13.0-221.0 mg kg^(-1)).In the soil the concentrations of aluminium,cadmium,cobalt,copper,iron,lead,nickel,and zinc vary between 33-457,0.0-0.0,0.0-0.4,0.1-88.7,14-50,0.3-4.1,0.2-0.8,and 4.0-20.3 mg kg^(-1) respectively.These findings enlighten the fact that copper is generally toxic in the soils as well as plants.Silene compacta has been recorded as a high copper accumulator,behaving as a healthy plant on the polluted sites of the area alongside the Murgul creek(especially at 600 m).This study stresses the fact that it is imperative to assess and monitor the levels of heavy metals in the environment due to anthropogenic activities,including mining,for evaluation of human exposure and for sustainable environment.

Analysis of TESS Field Eclipsing Binary Star V948 Her: A Pulsating or Non-pulsating Star?

Pulsating stars occupy a significant place in the H-R diagram and it was thought that all stars inside the classical instability strip should pulsate. However, recent studies showed that there are many non-pulsating stars located inside the classical instability strip. The existence of these non-pulsating stars is still a mystery. To deeply understand the properties of these non-pulsating and pulsating stars, one needs precise fundamental stellar parameters(e.g. mass).For this purpose, the eclipsing binaries are unique systems. Hence, in this study, we present the TESS data analysis of one candidate pulsating eclipsing binary system, V948 Her. TESS data were used for the binary modeling with the literature radial velocity measurements, and the precise fundamental parameters of the system were obtained. The system’s age was derived as 1 ± 0.24 Gyr. The positions of the binary components in the H-R diagram were examined and the primary component was found inside the δ Scuti instability strip. However, in the frequency analysis of TESS data, we found no significant pulsation frequencies. Only the harmonics of the orbital periods were obtained in the analysis. Therefore, the system was classified as a non-pulsator. V948 Her is an important object to understand the nature of non-pulsating stars inside the δ Scuti instability strip.

Candidate Eclipsing Binary Systems with aδScuti Star in Northern TESS Field

The existence of pulsating stars in eclipsing binaries has been known for decades.These types of objects are extremely valuable systems for astronomical studies as they exhibit both eclipse and pulsation variations.The eclipsing binaries are the only way to directly measure the mass and radius of stars with a good accuracy(≤1%),while the pulsations are a unique way to probe the stellar interior via oscillation frequencies.There are different types of pulsating stars existing in eclipsing binaries.One of them is theδScuti variables.Currently,the known number ofδScuti stars in eclipsing binaries is around 90 according to the latest catalog of these variables.An increasing number of these kinds of variables is important to understand the stellar structure,evolution and the effect of binarity on the pulsations.Therefore,in this study,we focus on discovering new eclipsing binaries withδScuti component(s).We searched within the northern Transiting Exoplanet Survey Satellite(TESS)field with a visual inspection by following some criteria such as light curve shape,the existence of pulsation like variations in the out-of-eclipse light curve and the T_(eff) values of the targets.As a result of these criteria,we discovered some targets.The orbital variations were first removed from the TESS light curves and frequency analysis was performed on the residuals.The luminosity,and absolute and bolometric magnitudes of the targets were calculated as well.To find how much of these parameters represent the primary(more luminous)binary component,we also computed the flux density ratio of the systems by utilizing the area of the eclipses.In addition,the positions of the systems in the H-R diagram were examined considering the flux density ratios.As a consequence of the investigation,we defined 38 candidateδScuti stars and also one Maia variable in eclipsing binary systems.

Performance Analysis of an Autoconfiguration Addressing Protocol for Ad Hoc Networks

Autoconfiguration protocols are important in maintaining mobile ad hoc networks (MANETs). In this paper, we present an autoconfiguration protocol called the one-step addressing (OSA) protocol characterized by its simplicity. Mathematical model is developed to evaluate the performance of the proposed protocol. The results of the model, which are validated by the simulation results, show that the OSA protocol outperforms the well-known token-based protocol in terms of both latency and communications overhead.

Spectral Density Estimation of Continuous Time Series

This paper studies spectral density estimation of a strictly stationary r-vector valued continuous time series including missing observations. The finite Fourier transform is constructed in L-joint segments of observations. The modified periodogram is defined and smoothed to estimate the spectral density matrix. We explore the properties of the proposed estimator. Asymptotic distribution is discussed.

Numerical Study of the Effect of Thermosiphon on the Vertical Dispersion of Pollutants

The dispersion of pollutants in urban environments is a major problem. Because of this fact our study comes to propose prevention and security system against the dispersion of releases and fumes from industrial smokestacks. The system is modeled by a plume-thermosiphon interaction flow resulting from a vertical cylinder open at both ends with a generating source of the plume centered at the opening of the cylinder. The cylindrical wall heats under the effect of the thermal radiation emitted by the generator source, which causes a flow of thermosiphon around the flow of the thermal plume. In order to determine the radiosity of radiation leaving the wall we have been used the Simpson quadrature and the Gaussian elimination method with a dominant pivot. Numerical simulations have been executed for different positions of the thermosiphon compared to the plume source, and for a number of Rayleigh fixed Ra = 10＋7, and a radius of the hot source corresponds to R＊ = 0.46. The results oftbe numerical model that we have been developed, help first identify the behavior of pollutants from the dynamic and thermal point of view and then explore the different locations of the thermosiphon compared to the source of the plume which causes a major influence on the dispersion of pollutants.

Role of ZnO-CeO_2 Nanostructures as a Photo-catalyst and Chemi-sensor

ZnO-CeO2 nanostructures were synthesized by simple and effcient low temperature method. The structure and morphology of the ZnO-CeO2 nanostructures were characterized by X-ray powder diffraction （XRD） and field emission scanning electron microscopy （FESEM）, which revealed elongated shaped CeO2 nanoparticles with diameters of 40–90 nm distributed on the surface of elongated ZnO nanostructures with diameters of 50–200 nm （edge–centre）. Further the structure of the synthesized ZnO-CeO2 nanostructure was supported by Raman spectra and Fourier transform infrared spectroscopy （FTIR）. UV-vis absorption spectrum was used to confirm the optical properties of the CeO2 doped ZnO nanostructures. Photo-catalytic activity of CeO2 doped ZnO nanostructure was evaluated by degradation of acridine orange and methylene blue which degraded 84.55% and 48.65% in 170 min, respectively. ZnO-CeO2 nanostructures also showed good sensitivity （0.8331 μA·cm-2·（mol/l）-1） in short response time （10 s） by applying to chemical sensing using ethanol as a target compound by I-V technique. These degradation and chemical sensing properties of ZnO-CeO2 nanostructures are of great importance for the application of ZnO-CeO2 system as a photo-catalyst and chemical sensor.