Background and Objectives: Dental caries is a breakdown of the teeth enamel due to harmful bacteria, lack of oral hygiene, and sugar consumption. The acid-producing bacterium Streptococcus mutans is the leading cause of dental caries. Dextra- nase is an enzyme that can degrade dextran to low molecular weight fractions, which have many therapeutic and industrial applications. The purpose of the present study was to isolate a novel dextranase-producing bacteria from asource (molasses). The cell-free extracts containing dextranases were tested as antibiofilm agents. Materials and Methods: Dextranase-producing bacteria were identified using phenotypic and genotypic methods such as 16S rRNA gene sequencing and enzymatic characterization. Results: The highest six dextranase-producing bacterial isolates were Bacillus species. The best conditions for dextranase productivity were obtained after 72hours of culture time at pH 7. The addition of glucose to the medium enhanced the pro- duction of the enzymes. The cell-free extract of the six most activeisolates showed remarkable activity against biofilm for- mation by Streptococcus mutans ATCC 25175. The highest inhibition activities reached 60% and 80%for Bacillus velezensis and Pseudomonas stutzeri, respectively. Conclusion: Therefore, our study added to the current dextranase-producing bacteria with potential as a source of dextra- nases.

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ChurchThe Holy Virgin Mary El-Shamyia dome of altar Assiut.This study aims to identify the ancient Church of the Virgin Mary, which was not published before. It is located in the village of Al-Shamiya in Sahel Selim, Assiut Governorate. Unfortunately, despite all ancientness of this church, it was not mentioned in the ancient books of history. It is well known that the churches and monasteries of the east bank of the Nile did not receive sufficient attention from the ancient historians, unlike the monasteries of the West Bank. These churches adopt the Coptic Byzantine style in their design, taking the form of a cross with an octagonal central dome made of wood and surrounded by four sections that take the shape of a cross. It preserves some ancient antiquities such as the iconostasis, wooden beams, the ancient baptistery and its beautiful minaret, in addition to the most important masterpiece in the church, which is the dome of the altar. This study records the architectural outline of the church and its horizontal and vertical projections, which is published for the first time in this research.

Water Kinetic energy downstream the hydraulic structures must be dissipated so as to stop severe scouring downstream apron and the failure of hydraulic structures. The shut block and sills with different forms are employed to disturb water and dissipate great amount of water energy through formation of a hydraulic jump in the stilling basin. Engineers have designed and used many alternative kinds of energy dissipators in order to shield hydraulic structures against scouring. The most task of the hydraulic designers is a way to dissipate a major part of water energy behind the vertical/radial gates by using more practical tools. The aim of this study is to get a better place to put the non-traditional sills to dissipate the resulting energy behind the vertical control gates. The hydraulic installations resulting from high speeds and different flows, which result in the occurrence of scour and erosion of the waterway behind these structures. The authors install a sill in several unconventional forms and study the efficient in dissipating kinetic energy. downstream hydraulic structures by installing it on relative dimensions of the gate Lb / Lf. Where Lf is that the length of the floor, Lb, distance from the gate, this was achieved to see the simplest position of the sill, aiming to reach the most energy dissipation and also the minimum length for the hydraulic jump. Experimental study has been conducted in glassed wall flume with square cross section of (30 cm x 30 cm) and length of 4.00 m with transparent vertical sides, located in hydraulic lab -Faculty of Engineering -Al-Azhar University in Cairo, levels and water depths are measured. As well as the levels and depths of scour within the channel sector. The effect of the sill on different positions was investigated and also the results were discussed. It was found that the best place to install the sill to dissipate the energy within the middle length of the floor and also the most effective ratio is (Lb / Lf) = 0. 50.

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