in this work the effect of electrolytes on hydrate formation was investigated. to do so, a new model was used in predicting the hydrate formation conditions in presence of both single and mixed electrolyte solutions. the new model is based on the van der waals - platteeuw hydrate equation of state. in order to evaluate the values for the activity of water in electrolyte solutions the simplified...

in this study, alkaline colloidal silica was prepared by titration of an alkaline solution such as sodium silicate with silicic acid in constant range of ph  .this constant range of ph was achieved by using concentrated soduim silicate solutions as ph adjusting solutions during titration.the sodium silicate solutions  having a variety of concentrations were passed  through ion-exchange resin to...

in this paper, a new fractional sub-equation method is proposed for finding exact solutions of fractional partial differential equations (fpdes) in the sense of modified riemann-liouville derivative. with the aid of symbolic computation, we choose the space-time fractional zakharov-kuznetsov-benjamin-bona-mahony (zkbbm) equation in mathematical physics with a source to illustrate the validity a...

it is proved that acidic soft drinks that are commonly used, have an adverse effect on dental structures, and may deteriorate oral heath of our patients and orthodontic appliances. the aim of this study was to compare the effect of yoghurt drink with other soft drinks on the shear bond strength of orthodontic brackets.seventy-five first premolar teeth extracted for orthodontic purposes were sel...

the principal aim of this paper is to serve the numerical solution of an integral-algebraic equation (iae) by using the bernoulli polynomials and the residual correction method. after implementation of our scheme, the main problem would be transformed into a system of algebraic equations such that its solutions are the unknown bernoulli coefficients. thismethod gives an analytic solution when t...

conclusions dialysis with cool dialysate is a simple and cheap nondrug method, which was readily accepted by the patients. this method could significantly reduce the severity of pruritus in patients during dialysis. results before the intervention, there was no significant between-group difference in the severity of pruritus (p < 0.05). after the intervention, the severity of pruritus was signi...

nickel is one of the toxin heavy metals in surface waters. developing new approaches aimed at removing heavy metals from aqueous solutions that are simultaneously economical and environmentally friendly is of great importance. the purpose of this study will be using nano-lignocellulose adsorbent as a natural material to remove nickel heavy metal. in this study, several important environmental p...

in this article, we prove the existence of extremal positive solution for the distributed order fractional hybrid differential equation$$int_{0}^{1}b(q)d^{q}[frac{x(t)}{f(t,x(t))}]dq=g(t,x(t)),$$using a fixed point theorem in the banach algebras. this proof is given in two cases of the continuous and discontinuous function $g$, under the generalized lipschitz and caratheodory conditions.

background: lead (pb) is a heavy metal that is widely utilized in industries. it contaminates soil and groundwater. its non-biodegradability, severe toxicity, carcinogenicity, ability to accumulate in nature and contaminate groundwater and surface water make this toxic heavy metal extremely dangerous to living beings and the environment. therefore, technical and economic methods of removing pb ...

this paper presents approximate analytical solutions for nonlinear oscillators using the multi-step homotopy analysis method (msham). the proposed scheme is only a simple modification of the homotopy analysis method, in which it is treated as an algorithm in a sequence of small intervals (i.e. time step) for finding accurate approximate solutions to the corresponding problems. several illustrat...