Effective viscosity of non-gravitactic Chlamydomonas Reinhardtii microswimmer suspensions

Active microswimmers are known to affect the macroscopic viscosity of suspensions in a more complex manner than passive particles. For puller-like microswimmers an increase in the viscosity has been observed. It has been suggested that the persistence of the orientation of the microswimmers hinders the rotation that is normally caused by the vorticity. It was previously shown that some sorts of algaes are bottom-heavy swimmers, i.e. their centre of mass is not located in the centre of the body. In this way, the algae affects the vorticity of the flow when it is perpendicular oriented to the axis of gravity. This orientation of gravity to vorticity is given in a rheometer that is equipped with a cone-plate geometry. Here we present measurements of the viscosity both in a cone-plate and a Taylor-Couette cell. The two set-ups yielded the same increase in viscosity although the axis of gravitation in the Taylor-Couette cell is parallel to the direction of vorticity. In a complementary experiment we tested the orientation of the direction of swimming through microscopic observation of single \textit{Chlamydomonas reinhardtii} and could not identify a preferred orientation, i. e. our specific strain of \textit{Chlamydomonas reinhardtii} are not bottom-heavy swimmers. We thus conclude that bottom heaviness is not a prerequisite for the increase of viscosity and that the effect of gravity on the rheology of our strain of \textit{Chlamydomonas reinhardtii} is negligible. This finding reopens the question of whether origin of persistence in the orientation of cells is actually responsible for the increased viscosity of the suspension

ANALISIS PELAKSANAAN KINERJA GURU SD NEGERI 94/II MUARA BUNGO

This study aims to determine teacher performance in the aspects of lesson planning, learning implementation and learning evaluation. This type of research is qualitative research with a descriptive approach. The subjects of this study were teachers of SD Negeri 94 / II Muara Bungo. Research data were obtained through closed questionnaires with a Likert scale. The questionnaire consists of 39 statements. The results showed that the teacher's performance in preparing lesson plans was in the very good category. teacher performance in implementing learning has reached the very good category. Furthermore, for teacher performance in carrying out learning evaluations the majority are still in the good category, there are only two class teachers who have carried out learning evaluations by achieving the very good category. So the performance of teachers at SD Negeri 94 / II Muara Bungo from the aspects of planning, implementing and evaluating learning should always be improved so that the quality of learning is maintained.Penelitian ini bertujuan untuk mengetahui kinerja guru dalam aspek perencanaan pembelajaran, pelaksanaan pembelajaran dan evaluasi pembelajaran. Jenis penelitian ini yaitu penelitian kualitatif dengan pendekatan deskriptif. Subjek penelitian ini guru SD Negeri 94/II Muara Bungo. Data penelitian peroleh melalui angket tertutup dengan skala Likert. Angket terdiri dari 39 pernyataan. Hasil penelitian diperoleh bahwa kinerja guru dalam menyusun perencanaan pembelajaran berada pada kategori sangat baik. kinerja guru dalam melaksanakan pembelajaran telah mencapai kategori sangat baik. selanjutnya untuk kinerja guru dalam melaksanakan evaluasi pembelajaran mayoritas masih berada pada kategori baik, hanya ada dua guru kelas yang telah melaksanakan evaluasi pembelajaran dengan mencapai kategori sangat baik. Jadi kinerja guru di SD Negeri 94/II Muara Bungo dari aspek perencanaan, pelaksanaan dan evaluasi pembelajaran untuk selalu ditingkatkan agar terjaga kualitas pembelajarannya

Photofocusing: Light and flow of phototactic microswimmer suspension

We explore in this paper the phenomenon of photofocusing: a coupling between flow vorticity and biased swimming of microalgae toward a light source that produces a focusing of the microswimmer suspension. We combine experiments that investigate the stationary state of this phenomenon as well as the transition regime with analytical and numerical modeling. We show that the experimentally observed scalings on the width of the focalized region and the establishment length as a function of the flow velocity are well described by a simple theoretical model

A performance of 2 dimensional ultrasonic vibration assisted milling in cutting force reduction, on aluminium AL6061

This paper were investigate a performance of 2 Dimensional Ultrasonic Vibration assisted Milling (UVAM) toward Aluminium Al 6061. The focus is to find the performance of reduction of cutting force compared to the conventional machining in the industries shop floor. Due to the major effect of cutting force of production in industries, the excessive cutting force problem must be investigated deeply as it will cause shortens tool life and reduces the production rate. A scientific approach has been found in order to reduce the cutting force during machining which is integrating the ultrasonic concept into workpiece. The modelling of vibration cutting ratio has been simulated to find the time force contact and non-contact. Thus, less cutting force could be found. The ultrasonic vibration platform that generated by XY25XS from Cedrat Technologies is travelled in X direction as a feed movement. Thus, the X and Y axis vibration actuate along the workpiece for the machining process. The performance of UVAM in cutting force reduction found the superior benefits of UVAM is come from the alternating cycle’s between tool and workpiece. The comparison between UVAM and conventional machining in reduction of cutting force is 32%. The potential of the UVAM tool wear and tool life will be discussed deeply in finding and next in the conclusion section

Effect of T2 Fusarium toxin on adrenocortical function and immune response of growing pigs

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Ingvar Ekesbo and Stefan Gunnarsson: Farm Animal Behaviour Characteristics for Assessment of Health and Welfare. Book Review

Ingvar Ekesbo and Stefan Gunnarsson: Farm Animal Behaviour Characteristics for Assessment of Health and Welfare. Second edition. CABI Wallingford, Oxfordshire, UK, 2018. 341 pages, with innumerable photo illustrations. 18 × 24 cm. ISBN-13: 978 1 78639 139 1. Price: 60

The Effect of Drill Reamer Tool on Cutting Force and Temperature when Machining with Different Parameters and Cutting Condition

Normally in manufacturing process, drilling and reaming are separate processes. However a new tool is developed which combined both processes. In this study, the performance of a new drill reamer is studied in terms of cutting force and temperature under internal cooling, external cooling and minimum quantity lubricant (MQL) condition. Three types of tools are used to machine aluminum; 140° twist drill, 140° and 180° drill reamer. Various values of feed were involved while cutting speed and depth of cut are kept constant. From the result it showed that 140° twist drill has produced low cutting (thrust) force and temperature. In addition, low value of cutting force and temperature were also generated when applying low feed and internal cooling condition for all tools

The in vitro effect of Garden Thyme (Thymus vulgaris L.) extract on Brachyspira hyodysenteriae

Filtrates of a water extract of commercially available garden thyme (Thymus vulgaris L.) were used for studying its possible bactericidal effect on Brachyspira hyodysenteriae, the causative agent of swine dysentery, by agar-diffusion technique. Five of the six studied Brachyspira strains have proven to be sensitive and one moderately sensitive in the in vitro tests. It was concluded that water extract of garden thyme possesses inhibitory effects against B. hyodysenteriae. In vivo experiments are needed to check the validity of this conclusion