Using mineral admixtures in cement composites as a way to improve their mechanical and durability properties is a common practice in concrete technology. Among them silica fume and nano-silica effectively influence the composite's early and long-term properties. Due to the limited particle size distribution of nano and micro silica it is expected that the incorporation of some mineral additives with a size of greater than 500 nm may result in better mechanical and durability performance because of the filler effect. In this study, the effect of different percentages of TiO2 on mechanical properties of cement composites containing nano-silica and silica fume was investigated. Six designs were tested for compressive strength with respect to zero, 2.5 and 5 percent replacement of cement with TiO2. The addition of TiO2 has led to an increase in compressive strength. The best results from the sample with 2.5% TiO2 are obtained. This could be due to the effect of TiO2 particles filling. Comparison of SF3, SF2 and SF1 at 28 days of age showed that SF2 increased the compressive strength. This shows that TiO2 has a great potential for improving the mechanical properties of composite cement.The results showed that the addition of TiO2 had a positive effect on compressive strength. Manuscript profile

Using mineral admixtures in cement composites as a way to improve their mechanical and durability properties is a common practice in concrete technology. Among them, silica fume and nano-silica effectively influence the composite's early and long-term properties. Due to the limited particle size distribution of nano and micro-silica, it is expected that the incorporation of some mineraladditives with a size greater than 500 nm may result in better mechanical and durability performance because of the filler effect. In this study, the effect of different percentages of TiO2 on the mechanical properties of cement composites containing nano-silica and silica fume was investigated. Six designs were tested for compressive strength with respect to zero, 2.5, and 5 percent replacementof cement with TiO2. The addition of TiO2 has led to an increase in compressive strength. The best results from the sample with 2.5% TiO2 are obtained. This could be due to the effect of TiO2 particles filling. Comparison of SF3, SF2, and SF1 at 28 days of age showed that SF2 increased the compressive strength. This shows that TiO2 has a great potential for improving the mechanical properties ofcomposite cement. The results showed that the addition of TiO2 had a positive effect on compressive strength. Increasing TiO2 nanoparticles content of more than 3 wt% is caused to reduce the compressive strength according to past studies. But in this study is shown that by adding 3% nanocillis or 20% silicified to increased TiO2 nanoparticles content of more than 3% wt, the results ofcompressive strength are not reduced. The use of 3% combined nano-silica or 20% silicafium will cover this defect of increased TiO2 nanoparticles content ofmore than 3% wt. Manuscript profile

Using mineral admixtures in cement composites as a way to improve their mechanical and sustainable environmental properties is a common practice in concrete technology. Among them nano-silica effectively influences the composite's early and long-term properties. In this study, the effect of different percentages of TiO2 (0, 2.5 and 5 %) on self-cleaning properties and water absorption of cement composites containing nano-silica were investigated. according to the use of different cementitious material (nano-silica) and TiO2 in mix proportions, to obtain mixtures with a desirable workability, superplasticizer was added in different volume percentages.Better size distribution and pore refinement lead to a denser cement matrix with low porosity which in turn considerably lower the water absorption of the cement composites. the maximum final water absorption according to ASTM C497 is 9% for method A and 8.5% for method B. Comparsions of water absorption tests as a result of adding of TiO2 and nano-silica in concrete show that the maximum final water absorption is 4.9% in N1 design mixture and the minimum final water absorption is 4.3% in N2 design mixture.The incorporation of TiO2 has positively affected the results for nano-silica containing specimens. A decrease of 6.5% and 11.1% between N1 and N3 respectively shows the positive effect of TiO2 on decrease of water absorption. The results show that TiO2 along with nanosilica has great potential for improving the environmental and self- cleaning properties of concrete facades of buildings in cities exposed to high levels of cleanliness. Manuscript profile

Pollution of water by heavy metals is a major problem such as mercury, lead, cadmium, cobalt, etc. The presence of toxic metals in the environment has detrimental effects on human and animal health and disrupts the balance and order of the ecosystem. Therefore, it is necessary to study the ways to eliminate these pollutants. The aim of this study was to compare nickel metal uptake by biological uptake methods with the help of bacterium and brown algae Sargasom, Focus and Grasilaria red algae and nanotechnology method. Based on the previous interpretations, the processes of removal of nickel from industrial wastewater was compared. Research question is that which method is more effective for removal of heavy metals? Results show that biosorption, as an environmentally friendly method, has a brilliant performance and is a low-cost internal method for wastewater treatment. The biological treatment of effluents is carried out by bacteria, some fungi, algae and protozoa to examine the conversion of effluent into a harmless state. Also results show that Iron-based nanostructured particles are capable of decomposing highly stable contaminants such as perchlorate compounds, air nitrate, heavy metals (nickel and mercury) and radioactive materials such as uranium dioxide. Nanostructured particles are used for immediate treatment of sediments, water treatment and liquid waste. Manuscript profile

As result of density difference between seawater and fresh water in coastal aquifers, a transition zone between two fluids is formed. A wedge of saltwater can be entered in coastal areas to the aquifer. Seawater intrusion rate and extent of transition zone depends on several factors including: changes in sea level, aquifer characteristics, hydrologic conditions of upstream, discharging from the aquifer, tidal and seasonal fluctuations of sea water. In this paper height of interface between seawater and freshwater in Mazandaran coastal aquifers is calculated by relationships that have been used in previous researches. Then Babol– Amol aquifer has reviewed by using of existing data in Water Company of Mazandaran and past researches. According to the available information, the development of exploitation of three zones (Alashroud to Haraz, Haraz to Babolroud and Babolroud to Talar river in Amol- Babol aquifer in south of Caspian Sea) for distances less than 2000 m to sea is possible in the Haraz to Alash river. The total amount of water from this study to can be discharged in the three regions is 505 million cubic meters, based on available data. According to statistics, 458 million cubic meters of these three areas are allowed to be discharged. Therefore, taking into account the withdrawal of unallowable wells, it can be assumed that the saltwater intrusion has more than 2000 meters to the coast. The results of this study are based on the hydrodynamic parameters of the aquifer for the past 9 years and seawater intrusion may be aggravated by climate change and hydrodynamic parameters change of in this aquifer. Therefore, it is necessary to carefully study hydrodynamic parameters of this aquifer. Manuscript profile

سدها و بندهای انحرافی موانعی برای جلوگیری از مهاجرت ماهیها در طول رودخانه به حساب می‌آیند. به منظور رفع این مشکل در طراحی سد، یک سازه­ی هیدرولیکی تحت عنوان راه ماهی در کنار سد تعبیه می‌شود؛ بنابراین، مساله­ی زیست محیطی طرح احداث بندهای انحرافی با احداث راه ماهی انعطاف پذیر حل می‌گردد. منظور از سازه­ی راه‌ماهی انعطاف‌پذیر، راه ماهی با خروجی قابل تنظیم با نوسان سطح آب می‌باشد. خروجی راه ماهی عبارت است از یک سرریز با جریان آزاد که در کناره­ی نهر و عمود بر آن تعبیه شده و اجازه می‌دهد تا در موقعی که ارتفاع آب بالاتر از تاج سرریز است، مقداری از آب از روی آن خارج شود. بر اثر نوسان سطح آب رودخانه، بده­ی عبوری از سازه­ی راه ماهی نیز تغییر یافته، و در نتیجه، عملکرد سازه­ی راه ماهی دچار ضعف می گردد. در این مقاله به تحلیل عدم قطعیت نیمرخ سطح آب و ارتفاع تاج سرریز در دهانه­ی خروجی سازه­ی راه ماهی با استفاده از تحلیل خطرکردن باکاربرد MFOSM (mean first order second moment) پرداخته ‌شده، سپس طراحی ابعاد بهینه­ی دهانه­ی خروجی سازه­ی راه ماهی بر اساس آن تحقق می­یابد Manuscript profile