The Adsorption of CHS-1 Resin for Cr (VI) of Low Concentration from Electroplating Wastewater

AbstractThe adsorption property of CHS-1 resin for Cr (VI) was investigated by chemical analysis. Experiment results show that CHS-1 resin has the best adsorption ability for Cr (VI) at pH=2-3. The exchange adsorption rate of the resin for Cr (VI) at low concentration is controlled by liquid film diffusion and chemical reaction. The behavior obeys the Freundlich isotherm and Langmuir equation. Its saturated sorption capacity is 347.22mg/g at 298K. The thermodynamic adsorption parameters, enthalpy change ΔH and free energy change ΔG298 of the adsorption are 1.39kJ/mol and -5.3kJ/mol. Cr (VI) adsorbed on CHS-1 resin can be eluted by 5% NaOH -5% NaCl quantitatively without apparent decrease in sorption capacity

Threshold regression with threg

In this presentation, I introduce a new Stata command called threg. The command estimates regression coefficients of a threshold regression model based on the first hitting time of a boundary by the sample path of a Wiener diffusion process. The regression methodology is well suited to applications involving survival and time-to-event data. This new command uses the MLE routine in Stata for calculating regression coefficient estimates, asymptotic standard errors, and p-values. An initialization option is also allowed, as in the conventional MLE routine. The threg command can be carried out with either calendar or analytical time scales. Hazard ratios at selected time points for specified scenarios (based on given categories or value settings of covariates) can also be calculated by this command. Furthermore, curves of estimated hazard functions, survival functions, and probability distribution functions of the first hitting time can be plotted. Function curves corresponding to different scenarios can be overlaid in the same plot for a comparative analysis to give added research insights.

Characterization of CoTiO3 Nanocrystallites Prepared by Homogeneous Precipitation Method

Nanocrystalline cobalt titanate (CoTiO3) has been synthesized from a well-mixed precursor. The precursor was prepared by a homogeneous precipitation method, in which urea was used as the precipitator. The as-synthesized sample is a mixture of CoTiO3 and rutile nanocrystallites with mean sizes of around 50 nm. It strongly absorbs visible light in the wavelength range of 500-690 nm besides ultraviolet light (wavelength < 370 nm). We found the synthetic CoTiO3 is a semiconducting material with a direct band gap of 2.53 eV. The green CoTiO3 has two absorbance peaks at the wavelengths of 537 and 606 nm, which correspond to the photon energies of 2.31 and 2.05 eV, respectively. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3195

(E)-N′-[(2-Hydroxynaphthalen-1-yl)methylidene]nicotinohydrazide

In the mol­ecule of the title compound, C17H13N3O2, the naphthyl ring system and the pyridine ring form a dihedral angle of 12.2 (3)°. An intra­molecular O—H⋯N hydrogen bond generates a six-membered ring with an S(6) ring motif. This also contributes to the relative overall near planarity of the mol­ecule [r.m.s. deviation of all 22 non-H atoms = 0.107 (5) Å]. In the crystal, mol­ecules are linked through inter­molecular N—H⋯N hydrogen bonds, forming chains along the a axis

6-Chloro-3-nitro-N-(propan-2-yl)pyridin-2-amine

There are two mol­ecules in the asymmetric unit mol­ecule of the title compound, C8H10ClN3O2. Intra­molecular N—H⋯O hydrogen bonds stabilize the mol­ecular structure. There are no classical inter­molecular hydrogen bonds in the crystal structure

Structural design of a silicon six-wafer micro-combustor under the effect of heat transfer boundary condition at the outer walls

The aim of this investigation was to establish a methodology for designing highly stressed micro fabricated structures by studying the structural design issues associated with a silicon six–wafer micro combustor under the effect of heat transfer boundary condition at the outer walls. Some experimental and numerical simulation results have indicated that the flame can not be sustained in the micro combustor if the poor heat transfer coefficients at the outer wall are present. This could cause the combustor wall temperature higher than the auto ignition temperature of reactants and results in the upstream burning. Since silicon has relatively poor high temperature strength and creep resistance when the temperature is above the brittle to ductile transition temperature (BDTT), e.g. 900K, the combustion in the recirculation jacket could possibly damage the micro combustor due to the high wall temperature

3-(4-Bromo­phen­yl)-4-[2-(4-nitro­phen­yl)hydrazin­yl]furan-2(5H)-one

In the title compound, C16H12BrN3O4, the furan-2(5H)-one ring forms a dihedral angle of 33.19 (9)° with the 4-bromo­benzene unit and is nearly perpendicular to the 4-nitro­benzene segment, making a dihedral angle of 89.93 (10)°. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules, generating an infinite chain along [010]. The chains are linked into a three-dimensional network by C—H⋯O, C—H⋯π and π–π contacts [centroid–centroid separation = 3.805 (2) Å]

Prevalence survey on pterygium among people aged 40 and above in Hengli Town of Dongguan

AIM:To investigate the prevalence of pterygium of the household population aged 40 and above in Hengli Town of Dongguan.<p>METHODS: Using the method of cluster random sampling, select 3 628 people aged 40 and above in four villages and one community for visual examination, intraocular pressure check, slit lamp examination and questionnaire.<p>RESULTS: The actual number of subjects was 3 393 people, and examination rate was 93.52%. We detected 843 patients with pterygium. The prevalence of pterygium was 24.85%.<p>CONCLUSION: There is high prevalence of pterygium in Dongguan area. The prevalence of pterygium is related with age and working environment, but has no relation with gender