Lignans are natural products widely distributed in the plant kingdom. They are composed of two β-β-linked phenylpropane (shikimate-derived biogenetic subunits). Although the backbone of lignans is composed of phenylpropane units, there is enormous diversity in the structure of lignans leading to different classes of lignans, such as γ-butyrolactone derivatives, eg. Hymatairesinol, bicyclooctadiene derivatives, e.g. pinoresinol, tetrahydrofuran derivatives e.g.lariciresinol, di-arylbutandiol derivatives, e.g. secoisolariciresinol. Introduction of a further carbon –carbon linkage leads to a class of lignans collectively known as cyclolignans such as tetrahydro-naphthalene derivatives, for example podophyllotoxin. Lignans ha

     In this paper, we experimentally studied the effects of optical power of semiconductor laser on the electrical properties of silicon diode of an exposed device. The experimental results showed that the laser diode light of different optical powers (2, 3, and 4 mW) had effects on the silicon diode that are somewhat similar to those of thermal treatment. A shift in the current-voltage curve to the left side was also noticed, which led to a non-linear decrease of the barrier voltage of the diode by the effect of laser light. We also reveal a decrease by 344.8 nA/mW in the reverse saturation current of the silicon diode as a result of exposure to laser light. The forward resistance of the silicon diode decreased with

Background: Surface treatment of machined dental zirconia for enhancement of the adhesion to resin cement, using Er,Cr:YSGG  Laser. Materials and Methods: Total number of 42 zirconia disc specimens (9 mm diameter, and 2 mm height) was sintered according to the manufacturer instruction. They are divided into six groups, each group of seven samples. Laser groups (Experiment parameters) were depend on laser total irradiation time, pulse duration, and power. Group (A): 20 sec., 60 µs pulse duration. Group (B): 30 sec., 60 µs pulse duration. Group (C): 40 sec., 60 µs pulse duration. Group (D): 20 sec., 700 µs pulse duration. Group (E): 30 sec., 700 µs pulse duration, with different powers used (1, 1

The holmium plasma induced by a 1064-nmQ-switched Nd:YAG laser in air was investigated. This work was done theoretically and experimentally.  Cowan code was used to get the emission spectra for different transition of the holmium target. In the experimental work, the evolution of the plasma was studied by acquiring spectral images at different laser pulse energies (600,650,700, 750, and 800 mJ). The repetition rates of (1Hz and 10Hz) in the UV region (200-400 nm). The results indicate that, the emission line intensities increase with increasing of the laser pulse energy and repetition rate. The strongest emission spectra appeared when the laser pulse energy is 800mJ and 10 Hz repetition rate at λ= 345.64nm, with the maximum intensi

The aim of this research is to design and construct a
semiconductor laser range finder operating in the near infrared range
for ranging and designation. The main part of the range finder is the
transmitter which is a semiconductor laser type GaAs of wavelength
0.904 μm with a beam expander and the receiver; a silicon pin
detector biased to approve the fast response time with it's collecting
optics. The transmitters pulse width was 200ns at a threshold current
of 10 Ampere and maximum operating current of 38 Ampere. The
repetition rate was set at 660Hz and the maximum operating output
power was around 1 watt. The divergence of the beam was 0.268o
the efficiency of the laser was 0.03% at a duty cycle of 1.32x

Abstract: Background: Optical biosensors offer excellent properties and methods for detecting bacteria when compared to traditional analytical techniques.  It allows direct detection of many biological and chemical materials.  Bacteria are found in the human body naturally non-pathogenic and pathologically, as they are found in other living organisms.  One of these bacteria is Escherichia coli (E. coli) which are found in the human body in its natural and pathogenic form. E.coli bacteria cause many diseases, including Stomach, intestines, urinary system infections, and others. The aim of this study: is sensing and differentiation between normal flora and pathogenic E.coli. Material and method:

The measurement of minority carrier lifetime (MCLT) ofp-n Si fabricated with aid of laser doping technique was reported. The measurement is achieved by using open circuit voltage decay (OCVD) technique. The experiment data confirms that the value of MCLT and proftle of Voc decay were very sensitive to the doping laser energy.