Calibration Estimation for Ratio Estimators in Stratified Sampling for Proportion Allocation

Calibration has established itself as an important methodological instrument in large scale production of statistics. In this paper, we propose calibration estimation for ratio estimator in stratified sampling and derive the estimator of the variance of the calibration estimation ratio estimator in stratified sampling in case proportion allocation

Partially pyrolyzed-non-activated olive stones: Characterization and utilization of olive stones partially-pyrolyzed at various temperatures for 2-chlorophenol removal from water

This paper reports the development of the chemical and structural properties of partially pyrolyzed olive stones (OS) (at 250, 400, 500, 600, 700 and 850 °C) intended for use as a less expensive and more environmental-friendly adsorbent within water treatment applications. The following properties were followed: mass loss, surface chemistry (acid/base titrations and IR analysis), crystalline matter and elemental analysis, SEM, BET and TGA analysis. The major mass loss (68%) occurred between 250 and 400 °C. Acidic oxides disappeared after 500 °C, while surface basicity increased with increasing pyrolysis temperature. The partially pyrolyzed-non-activated OS sorbents were used for 2-chlorohenol (2-CP) removal from water, where 2-CP uptake increased with increasing pyrolysis temperature. The maximum adsorption was recorded at pH 7 using the pyrolyzed OS at 850 °C, which was only 13% more than that of OS pyrolyzed at 600 °C (sorbent carb600). So that carb600 (adsorption capacity: 34.1 mg g−1) was recommended as a cost-effective-environmental-friendly adsorbent. The re-usability of carb600 for removing 2-chlorophenol from real water sample was evident, where ∼70% of its adsorption efficiency was reserved even in the presence of competing ions

Effects of Seawater on Setting Time and Compressive Strength of Concretes with Different Richness

Water is one of the main constituents of concrete. Although many types of water exist, fresh water is the mostly used in concrete industry. Fresh water is expected to be in a great shortage by 2050 according to UN world water development report. Incorporating seawater in concrete mixture can help in the expected problem of scarcity of fresh water. Also, in many cases seawater may be the only available water especially in coastal regions. Many reports mention various possibilities of using seawater in concrete without detrimental effect on concrete properties. In this study another beneficial effect of seawater over tap water was concluded. Setting tests of cement paste mixed with seawater was determined using Vicat apparatus and compared to tap water. Compressive strength tests at the age of 28 days of Portland cement concretes with varied quantity of cement i.e. 300, 350, 400, 450, and 500 kg, and mixed with seawater was also performed and compared to tap water. The results show that seawater affects standard consistency of cement paste and two percent increase was required in order to attain the same consistency as tap water. It shows also seawater slightly accelerates initial setting of cement but the effect is not so pronounced so as to cause a trouble in concrete and final setting time almost remains unaltered. Compressive strength tests show an increase in concrete strength mixed with seawater for all tested mixtures and depending on quantity of cement. It also shows a beneficial effect of seawater on compressive strength of rich concrete with quantity of cement 450 and 500 kg over tap water. Doi: 10.28991/cej-2021-03091695 Full Text: PD

On the stationary vibrations of a rectangular plate subjected to stress prescribed partially at the circumference

The stationary periodical problem of a vibrating rectangular plate, stressed at a segment while fixed elsewhere at one of its edges, is considered. Using the finite Fourier transformation, the problem is converted to a singular integral equation that in turn can be reduced to an infinite system of algebraic equations. The truncation of the algebraic system is justified

DEVELOPMENT OF EFFICIENT CLOUD POINT EXTRACTION METHOD FOR PRECONCENRATION AND SPECTROPHOTOMETRIC DETERMINATION OF NICKEL IN WATER SAMPLES USING 2-(BENZOTHIAZOLYLZAO)ORCINOL

Objective: Efficient cloud point extraction (CPE) methodology was developed for pre concentration of trace nickel in water samples prior to their determination by spectrophotometry.Methods: The method is based on the reaction of nickel with 2-(benzothiazolyl azo) orcinol reagent (BTAO) at pH 7.0 and micelle-mediated extraction using the nonionic surfactant Triton X-114 medium.Results: The surfactant-rich phase was diluted with methanol and the nickel content was determined at 558 nm. The optimum conditions (e. g. pH, reagent and surfactant concentrations, and temperature and centrifugation times) were evaluated and optimized. The proposed CPE method showed linear calibration within the range 10–250 ng/ml of nickel and the limit of detection of the method was 2.0 ng/ml with a pre concentration factor of  50. The relative standard deviation (RSD) and relative error were found to be 1.10% (N = 6). The interference effect of some cations and anions was also studied.Conclusion: The method was applied to the determination of nickel in water samples with a recovery from the spiked samples in the range of 95.85–98.50%. Â

Heat and freezing pre-thermal treatments as a means of freeing potatoes from mosaic virus and its effects on potato plants quality characters

The aim of the study was to control of potato mosaic virus by using hot-air, hot-water and freezing as a physical pre-thermal treatments. Infected tubers of Lady Rosetta and Mondial potato (Solanum tuberosum L.) cultivars were treated by hot-air and hot-water treatments at 55± 2 ̊ C and freezing treatment at -18±2 ̊ C for 1, 2, 3 and 4 hours.  Hot-air and freezing treatments showed complete elimination of mosaic virus from treated tubers. Hot-water treatment caused tuber damage at different exposure times. In this respect, hot-air treatment at 55± 2 ̊ C and freezing treatment at -18±2 ̊ C for two hours gave the best results of eliminating the virus from tubers and did not affect on economic characters of potato cultivars.

UTILITY OF CERTAIN σ AND π-ACCEPTORS FOR THE SPECTROPHOTOMETRIC DETERMINATION OF VORICONAZOL ANTIFUGAL DRUG IN PHARMACEUTICAL FORMULATION

Objective: Studies were carried out, for the first time, to investigate the charge-transfer reactions of voriconazole antifungal drug (VOR) as n-electron donor with the σ-acceptor iodine (I2) and various Ï€-acceptors: 7,7,8,8-tetracyanoquinodimethane (TCNQ); 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and p-chloranilic acid (p-CLA).Methods: The formation of the colored charge-transfer complexes were utilized in the development of simple, rapid and accurate spectrophotometric methods for the analysis of voriconazole in pure form as well as in its pharmaceutical formulation (tablets). Different variables affecting the reactions were studied and optimized.Results: Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9994–0.9999) were found between the absorbance and the concentration of voriconazole in the range of 2.0–120 μg mL−1. For more accurate analysis, Ringbom optimum concentration range was found to be between 4.0-110 μg mL-1. The limits of detection ranged from 0.36 to 1.23 μg mL−1andthe limits of quantification ranged from 1.20 to 4.10 μg mL−1. A Job's plot of the absorbance versus the molar ratio of voriconazole to each of acceptors under consideration indicated (1:1) ratio.Conclusion: The proposed methods were applied successfully for simultaneous determination of voriconazole in tablets with good accuracy and precision and without interferences from common additives. The results were compared favourably with the reported method.Â

Spatial and temporal resolutions pixel level performance analysis of the onboard remote sensing electro-optical systems

Formulas for determination of the interconnection between the spatial resolution from perspective distortions and the temporal resolution of the onboard electro-optical system for remote sensing application for a variety of scene viewing modes is offered. These dependences can be compared with the user’s requirements, upon the permission values of the design parameters of the modern main units of the electro-optical system is discussed

The biosorption of mercury by permeable pavement biofilms in stormwater attenuation

This study reports on the evaluation of the equilibrium, thermodynamics and kinetics of mercury (II) biosorption using a living biofilm, developed on a nonwoven polypropylene and polyethylene geotextile, typically used within the structure of Sustainable Drainage System (SuDS) devices. Batch biosorption assays were carried out with variables such as pH, initial concentrations, contact time, temperature and biofilm incubation time. Langmuir, Freundlich and Dubinin Radushkevich (D-R) models were applied to the equilibrium data which revealed the maximum biosorption capacities and efficiencies at pH 5.5 with a contact time of 120 min at 25 °C. With 20 mg L -1 added Hg (II), living biofilm samples with incubation times of 1, 7, 14, 21 and 28 days, biosorption values were 101.31 (55.72%), 24.41 (67.12%), 16.81 (61.37%), 9.70 (62.57%) and 13.34 (65.38%) mg g -1, respectively. Free mean biosorption energy from the D-R model was between 2.24 and 2.36 kJ mol -1 for all biofilm development incubation times, that revealed the physical biosorption mechanism for Hg(II). The thermodynamic studies showed that the Hg(II) biosorption of living biofilm was thermodynamically feasible and had a spontaneous and exothermic nature. Kinetic parameters revealed that Hg(II) biosorption onto living biofilm had a good correlation with a pseudo second-order kinetic model. FTIR spectra after biosorption suggested that amine, hydroxyl and carboxyl groups were the main functional groups available and responsible for Hg(II) biosorption onto living biofilm. Experimental data suggested that a living biofilm developed on a nonwoven polypropylene and polyethylene geotextile can be efficient in the removal of mercury ions from contaminated urban and industrial runoff. </p

Brain Emotional Learning Based Intelligent Decoupler for Nonlinear Multi-Input Multi-Output Distillation Columns

The distillation process is vital in many fields of chemical industries, such as the two-coupled distillation columns that are usually highly nonlinear Multi-Input Multi-Output (MIMO) coupled processes. The control of MIMO process is usually implemented via a decentralized approach using a set of Single-Input Single-Output (SISO) loop controllers. Decoupling the MIMO process into group of single loops requires proper input-output pairing and development of decoupling compensator unit. This paper proposes a novel intelligent decoupling approach for MIMO processes based on new MIMO brain emotional learning architecture. A MIMO architecture of Brain Emotional Learning Based Intelligent Controller (BELBIC) is developed and applied as a decoupler for 4 input/4 output highly nonlinear coupled distillation columns process. Moreover, the performance of the proposed Brain Emotional Learning Based Intelligent Decoupler (BELBID) is enhanced using Particle Swarm Optimization (PSO) technique. The performance is compared with the PSO optimized steady state decoupling compensation matrix. Mathematical models of the distillation columns and the decouplers are built and tested in simulation environment by applying the same inputs. The results prove remarkable success of the BELBID in minimizing the loops interactions without degrading the output that every input has been paired with