Physical Principles Governing Colloidal Particle Deposition at Low Reynold’s Number: Applications to Microbial Biofilms

Biofilms formed from the adhesion of microbes to a surface hold great relevance to public health and wastewater management. However, the physical principles underlying the attachment stage of biofilm formation, when individual microbes first come into contact with a substrate, are not well understood. Here I report on a model of colloidal particle attachment to a surface that incorporates the effects of diffusion, advection, gravity, and the hydrodynamic lift and drag forces experienced by polystyrene beads at low Reynold’s number. The simulation predicts attachment rates of 1.04x10^(-8)m/s, 0.73x10^(-8)m/s, and 1.29x10^(-8)m/s for beads of radius 0.25 µm, 0.55 µm, and 0.90 µm, respectively. Comparison to experimental data demonstrates that the calculated attachment rates approximate the observed rates, but that they tend to underestimate the experimental observations. The model could be further improved by the addition of other forces influencing particle deposition in a fluid environment

The Absolute Frame of Reference

The manuscript found the formula to calculate the real velocity of the earth and the maximum velocity in the universe, the values of the quantities after calculation as follows: V_earth = 1.852819296∗10^8 m/s.-- C_max = 4.8507438399∗10^8 m/s.-- In order to calculate the above results, the manuscript has built a reference frame transformation suitable for all types of motion(suitable for both linear motion and chaotic motion of the reference frame). This means that we will calculate the velocity of an object without using the distance S quantity of the object

Precise Measurement of Gravity Variations During a Total Solar Eclipse

The variations of gravity were measured with a high precision LaCoste-Romberg D gravimeter during a total solar eclipse to investigate the effect of solar eclipse on the gravitational field. The observed anomaly $(7.0 \pm 2.7) \times 10^{-8}$ m/s$^2$ during the eclipse implies that there may be a shielding property of gravitation

ANALISIS KINERJA TURBIN ANGIN SUMBU HORIZONTAL TIPE TSD 500 PADA BEBAN KONSTAN

Tujuan  penelitian  ini adalah untuk menganalisa kinerja turbin angin sumbu horizontal tipe TSD 500 pada beban konstan dengan menggunakan variasi kecepatan angin 8 m/s, 9 m/s, 10 m/s, 11 m/s, 12 m/s, 13 m/s, 14 m/s, dan untuk mendapatkan efisiensi sistem terbaik. Metode  penelitian  yang digunakan dengan cara melakukan pengujian pada turbin angin sumbu horizontal tipe TSD 500 menggunakan variasi kecepatan angin 8 m/s sampai 14 m/s untuk mendapatkan grafik karakteristik dan efisiensi sistem terbaik. Hasil pengujian dengan menggunakan variasi kecepatan angin 8 m/s sampai 14 m/s diantaranya pada kecepatan angin 8 m/s dibeban lampu 500 watt didapatkan nilai efisiensi sistem terbaik yaitu 12 %.  Kata Kunci :  Turbin horizontal TSD 500, karakteristik turbin, efisiensi siste

TURBIN ANGIN SUMBU HORIZONTAL TIPE TSD 500 PADA BEBAN KONSTAN

Tujuan penulisan tugas akhir ini adalah untuk menganalisa kinerja turbin angin sumbu horizontal tipe TSD 500 pada beban konstan dengan menggunakan variasi kecepatan angin 8 m/s, 9 m/s, 10 m/s, 11 m/s, 12 m/s, 13 m/s, 14 m/s, dan untuk mendapatkan efisiensi sistem terbaik. Metode penulisan tugas akhir yang digunakan dilakukan dengan cara melakukan pengujian pada turbin angin sumbu horizontal tipe TSD 500 menggunakan variasi kecepatan angin 8 m/s sampai 14 m/s guna untuk mendapatkan grafik karakteristik dan efisiensi sistem terbaik. Hasil dari pengujian yang dilakukan dengan menggunakan variasi kecepatan angin 8 m/s sampai 14 m/s diantaranya pada kecepatan angin 8 m/s dibeban lampu 500 watt didapatkan nilai efisiensi sistem terbaik yaitu 12 %.  Kata Kunci :Turbin horizontal TSD 500, karakteristik turbin, efisiensi siste

Ab-initio simulation of high-temperature liquid selenium

Ab initio molecular dynamics simulation is used to investigate the structure and dynamics of liquid Se at temperatures of 870 and 1370~K. The calculated static structure factor is in excellent agreement with experimental data. The calculated radial distribution function gives a mean coordination number close to 2, but we find a significant fraction of one-fold and three-fold atoms, particularly at 1370~K, so that the chain structure is considerably disrupted. The self-diffusion coefficient has values ($\sim 1 \times 10^{-8}$~m~s$^{-1}$) typical of liquid metals.Comment: 10 pages, 4 Poscript figures, uses REVTE

Precision stellar radial velocity measurements with FIDEOS at the ESO 1-m telescope of La Silla

We present results from the commissioning and early science programs of FIDEOS, the new high-resolution echelle spectrograph developed at the Centre of Astro Engineering of Pontificia Universidad Catolica de Chile, and recently installed at the ESO 1m telescope of La Silla. The instrument provides spectral resolution R = 43,000 in the visible spectral range 420-800 nm, reaching a limiting magnitude of 11 in V band. Precision in the measurement of radial velocity is guaranteed by light feeding with an octagonal optical fibre, suitable mechanical isolation, thermal stabilisation, and simultaneous wavelength calibration. Currently the instrument reaches radial velocity stability of = 8 m/s over several consecutive nights of observation

Electroformation in a flow chamber with solution exchange as a means of preparation of flaccid giant vesicles

A recently described technique (Estes and Mayer, Biochim. Biophys. Acta 1712 (2005) 152--160) for the preparation of giant unilamellar vesicles (GUVs) in solutions with high ionic strength is examined. By observing a series of osmotic swellings followed by vesicle bursts upon a micropipette transfer of a single POPC GUV from a sucrose solution into an isoosmolar glycerol solution, a value for the permeability of POPC membrane for glycerol, P = (2.09+/-0.82) x 10^{-8} m/s, has been obtained. Based on this result, an alternative mechanism is proposed for the observed exchange of vesicle interior. With modifications, the method of Estes and Mayer is then applied to preparation of flaccid GUVs.Comment: 13 pages, 10 figures, accepted for publication in Colloids and Surfaces B: Biointerface

Field Experiments With a Wind Tunnel on the Flight Speed of Some West African Mosquitoes (Diptera: Culicidae)

An open wind tunnel, down which air was blown from over a bait animal, was used in the field in the Gambia to measure the flight speed of host-seeking mosquitoes. Insects were trapped on an electrocuting grid fitted halfway up the tunnel. As the speed of air movement through the electrocuting grid was increased from 0-5 m/s, catches of Mansonia spp. fell off steeply, reaching negligible levels above 1-4 m/s. At air speeds lower than 0-5 m/s, catches at the grid were greatly reduced. Similar results were obtained for Anopheles ziemanni Grimb. and other species of Anopheles. It is concluded that the maximum flight speed of hostseeking females of all these species was in the range 4-1-8 m/s

Radial velocities of giant stars: an investigation of line profile variations

Since 1999, a radial velocity survey of 179 red giant stars is ongoing at Lick Observatory with a one month cadence. At present ~20-100 measurements have been collected per star with an accuracy of 5 to 8 m/s. Of the stars monitored, 145 (80%) show radial velocity (RV) variations at a level >20 m/s, of which 43 exhibit significant periodicities. Here, we investigate the mechanism causing the observed radial velocity variations. Firstly, we search for a correlation between the radial velocity amplitude and an intrinsic parameter of the star, in this case surface gravity (log g). Secondly, we investigate line profile variations and compare these with theoretical predictions.Comment: To appear in the proceedings of the Helas II workshop: Helioseismology, Asteroseismology and MHD Connections; published in the Journal of Physics: Conference Series, ed. L. Gizon; 7 pages, 5 figure