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Generation of Terahertz Radiation from Fe-doped InGaAsP Using 800 nm to 1550 nm Pulsed Laser Excitation

Generation of Terahertz Radiation from Fe-doped InGaAsP Using 800 nm to 1550 nm Pulsed Laser Excitation

The resistivities of the Fe:InGaAsP and Fe:InGaAs samples were also determined from the I-V characteristics of at least two devices fabricated from each wafer into Hall bar geometries (variation in resistivity was found to be <5 % between the two devices). The maximum resistivity for the Fe-doped InGaAsP wafer was about five times higher than that in the Fe:InGaAs materials (Fig. 4b), with the value of 10 kΩ cm (at 1 × 10 16 cm −3 Fe doping) being the highest reported resistivity for a material emitting THz radiation at 1550 nm. In general, provided photocurrent is sustained, having high resistivity enables a greater bias voltage to be applied to the emitter electrodes without breakdown occurring, and hence, high power THz emission can be obtained. We note that some difficulties were found in measuring the mobility of the charge carriers in our materials using Hall bar devices under magnetic fields. We think these difficulties arise from some magnetization interactions with the Fe doping.
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In vitro perforation of human epithelial carcinoma cell with antibody-conjugated biodegradable microspheres illuminated by a single 80 femtosecond near-infrared laser pulse

In vitro perforation of human epithelial carcinoma cell with antibody-conjugated biodegradable microspheres illuminated by a single 80 femtosecond near-infrared laser pulse

Abstract: Pulsed laser interaction with small metallic and dielectric particles has been receiving attention as a method of drug delivery to many cells. However, most of the particles are attended by many risks, which are mainly dependent upon particle size. Unlike other widely used particles, biodegradable particles have advantages of being broken down and eliminated by innate metabolic processes. In this paper, the perforation of cell membrane by a focused spot with transparent biodegradable microspheres excited by a single 800 nm, 80 fs laser pulse is demonstrated. A polylactic acid (PLA) sphere, a biodegradable polymer, was used. Fluorescein isothiocyanate (FITC)-dextran and short interfering RNA were delivered into many human epithelial carcinoma cells (A431 cells) by applying a single 80 fs laser pulse in the presence of antibody-conjugated PLA microspheres. The focused intensity was also simulated by the three-dimensional finite-difference time-domain method. Perforation by biodegradable spheres compared with other particles has the potential to be a much safer phototherapy and drug delivery method for patients. The present method can open a new avenue, which is con- sidered an efficient adherent for the selective perforation of cells which express the specific antigen on the cell membrane.
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Pulsed 980 nm short wavelength infrared neural stimulation in cochlea and laser parameter effects on auditory response characteristics

Pulsed 980 nm short wavelength infrared neural stimulation in cochlea and laser parameter effects on auditory response characteristics

Furthermore, we investigated the pulse width variation effects on OABR amplitude and latency. The results showed that no obvious changes were made on OABR when varying the pulse width from 100 to 800  μ s. The OABR wave III latency (4.09 ± 0.09 ms) and wave III peak amplitude (0.81  ±  0.05  μ V) were almost steady (shown in Fig.  6a, b). The results indicated that the pulse width variation between 100 and 800  μ s range had no remarkable influence on the OABR features. The possible mechanism may be that,after the stimulation intensity exceeded the threshold, the laser pulse peak power and the rising edge influenced the OABR, rather than the laser pulse duration. Once the laser pulse energy was deposited enough, the auditory neurons were effectively stimulated. Similar results were also presented in relevant study with longer wavelength infrared laser between 1.844 to 1.873  μ m, they suggested that the laser peak power was constant across varied pulse durations ranged from 100 to 1000  μ s, when evoking the same CAP intensity with 50  μ V amplitude [28].
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Study the Effect of Different Liquid Media on the Synthesis of Alumina (Al2O3) Nanoparticle by Pulsed Laser Ablation Technique

Study the Effect of Different Liquid Media on the Synthesis of Alumina (Al2O3) Nanoparticle by Pulsed Laser Ablation Technique

During laser ablation of alumina in ethanol small bubbles can be observed in the solution, while in water no bubbles were observed. At high pressure and high temperature, ethanol can decompose to form permanent gases. The formed permanent gases in ethanol solution aggregate to bubbles that can be seen during laser ablation. The gases bubbles in the path of laser beam in combination with ablated plasma and formed nanoparticles in earlier pulses weaken the laser light that couples to the target. It suggests that no oxidation occurs under the protection of ethanol solution. Therefore, ethanol is proposed to be an optimal substitute of water for fabricating pure materials colloid due to prohibition of ethanol surrounding media form oxidation. Table 1. shows the effect of ablation medium on domain size and UV-Visible absorption peak wavelength(nm) by using femtosecond laser (λ=800 nm mJ/pulse, τ =130 fs ,P.R.R =1KHz) for Al 2 O 3 NPs
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Treatment of Verrucous Epidermal Nevus Using Long Pulsed Nd: YAG Laser

Treatment of Verrucous Epidermal Nevus Using Long Pulsed Nd: YAG Laser

used for the treatment of superficial epidermal pigmented lesions [6,8]. Their wavelengths are absorbed by both intra- and extracellular water of the epidermis and dermis, which results in a non-specific destruction [8-10]. There is a relatively narrow margin of safety when treating epidermal nevi; if the treatment is too superficial with removal of the epidermis only, the nevus will recur and if it goes too deeply into the reticular dermis, hypertrophic scaring may develop [11]. In Previous studies, 585-nm Pulsed dye laser (PDL) has been used successfully in treatment of inflammatory linear verrucous nevus (ILVEN), which is a variant of epidermal nevi, by destructing the dilated blood vessels and decreasing the inflammatory process [12,13]. Based on the postulation that oxyhemoglobin in blood vessels has strong absorption peaks at wavelengths ranging from 585 to 595 nm of PDL and moreover has a significant, albeit more modest, absorption peak between 800 and 1,100 nm, long pulsed Nd -YAG laser (1064nm) have been used in the treatment of vascular defects as telangiectasia, portwine stains,
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Vol 28, No 4 (2018)

Vol 28, No 4 (2018)

laser in the continuous mode is effective but associated with considerable possibility of texture changes and post-therapeutic skin color alterations because of its uncontrollable penetration depth. This is in contrast to ultrapulsed CO2 laser mode that emits a considerably very high energy in extremely short pulses. Consequently the pulse duration lies outside the thermal relaxation time of skin hence minimizing the collateral destruction. 1,3

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Structural and Magnetoresistive Properties of Nanometric Films Based on Iron and Chromium Oxides on the Si Substrate

Structural and Magnetoresistive Properties of Nanometric Films Based on Iron and Chromium Oxides on the Si Substrate

quite suitable materials for thermo-tenso sensors. The reactive pulse laser deposition is one of the attractive methods for the nanometric film synthesis. The advan- tages of this method are effectivity, simplicity, envir- onmental safety, and deposition of the layers with precise thicknesses on the different substrates from the various chemical precursors. In other words, the RPLD method application in combination with the material selecting allows creating sensors with required parameters [5 – 7]. The iron oxide thin films with different sensing properties for thermo-photo- chemical sensors operating at moderate temperature were demonstrated. In the present work, we report on the studies of the magnetoresistive properties of nanometric films of iron and chromium oxides (Fe 2 O 3 − X (0 ≤ x ≤ 1),
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Single-Event Transient Measurement on a DC/DC PWM Controller Using Pulsed X-ray Technique

Single-Event Transient Measurement on a DC/DC PWM Controller Using Pulsed X-ray Technique

The DC/DC PWM controller under study is a triple regulator. It has two independent synchronously-rectified buck controllers and a linear controller to offer precise regulation of up to three voltage rails. The test circuit is shown in Figure 2. Each of the three soft-start pins is connected to a capacitive load. The PGOOD pin is an open-drain pull-down device. When power is first applied to the IC, the PGOOD output is pulled low indicating an initial condition. After all three soft-start pins complete their ramp up with no faults (no shorts detected on the switchers), the power is considered “GOOD” as indicated by a high PGOOD pin. The nominal output voltage for PGOOD is 5.7 V for this DC/DC PWM. Our previous testing [5] showed that a 6-μs SET pulse appeared on the PGOOD pin when the chip was irradiated with either heavy ions or pulsed laser beams. Our further analysis indicated that this is because the irradiation causes SET inside the PWM, which will cut off a NMOS current mirror on its propagation path when it is large enough. In this case, a 6-μs pulse is observed on PGOOD pin. On the other hand, if the SET inside the PWM is not large enough to cut off the NMOS current mirror, it will not propagate out and 6-μs pulse will not be observed on PGOOD pin. The 6-μs constant is the charging constant for a RC delay circuit connected to the current mirror. To sum up, a 6-μs pulse is only observed on PGOOD pin when the irradiation-induced SET inside the PWM is larger than a specific threshold. As
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The Potentials of Laser Cutting Technologies for Oil Palm Harvesting

The Potentials of Laser Cutting Technologies for Oil Palm Harvesting

According to Liu et al. (2011) the laser technology is capable of cutting agricultural materials such as tomatoes stalk cutting, based on two essential aspects. One is that the power density of focusing spot of this device is determined by both laser beam quality and properties of focusing system. It should be understood that this laser cutting method is based on the concept of burns and ablation and is different from machines that use blade. The factors affecting efficiency of laser cutting are diameter of surface, laser power, focal length and angle during cutting. Lawson (2009) analysed the laser market industry where the most active industrial laser technology product sector is fibre lasers with at low- and high-output power levels. However, the research and application of laser cutting technology in biomaterials have not been fully revealed. Oil Palm Fronds Optical Characteristic
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Pulsed Led’s Light at 650 nm Promote and at 470 nm Suppress Melatonin’s Secretion

Pulsed Led’s Light at 650 nm Promote and at 470 nm Suppress Melatonin’s Secretion

The difference was postulated to be due to photobiomodulation effect of the red light on the retinal tissue [2]. Recently red and near infrared light (red-NIR light 630 to 800 and over nm) produced by Light Emitting Di- odes (LED) is widely used in human and veterinarian medicine, although the molecular mechanisms involved are not clearly understood [8] [9]. Red-NIR light seems to have better penetrative capacity in tissue without thermal increase and optimal response in activating the chromophore’s cytochrome c oxidase activity at the level of the mitochondrial electron transport chain, which produces ATP [10]-[12]. Moreover, recent findings provide importantly new insight in photobiomodulation, in which nitric oxide (NO) synthesized also by cytochrome c oxidase has been implicated [13].
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LIGHT AND LASER THERAPY FOR CUTANEOUS LESIONS AND PILONIDAL DISEASE

LIGHT AND LASER THERAPY FOR CUTANEOUS LESIONS AND PILONIDAL DISEASE

Remlova et al. (2011) evaluated hemangioma treatment using four different types of lasers, namely, alexandrite, Er: YAG, CO (2), and pulsed dye laser (PDL). A group of 869 consecutive patients with hemangioma was retrospectively reviewed. The patients including in the study were divided into four groups according to the type of laser used: Alexandrite laser (n=85), CO (2) laser (n=78), Er: YAG laser (n=105), and PDL laser (n=601). All patients were treated in one session. The ablative systems vaporized the tissues until the hemangioma was removed. The non-ablative systems used one shot, which destroyed the hemangioma blood vessels. For the treatment efficacy analysis, the following factors were evaluated: therapeutic effect (yes vs. no), loss of pigment (yes vs. no), and appearance of scar (yes vs. no). From results it was evident that the therapeutic effect of all the lasers except alexandrite was very high; almost 100%. In the CO (2) and the Er: YAG laser groups a high percentage of side effects was also observed. Exposure to these lasers caused loss of pigment and scar formation in many cases. According to the authors, the best therapeutic effect, with only minor side effects, was achieved with the PDL laser.
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Different Coating Processes for Surface Hardening of Aluminium

Different Coating Processes for Surface Hardening of Aluminium

developing automatic laser cladding machines. Maximun process parameters must be manually set like laser power, laser focal point, substrate velocity, powder injection rate, etc., and thus it requires the attention of a specialized technician to ensure proper results of given parameters. With some sensors, control strategies are being designed such that constant observation from a technician.

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Pulsed Laser Deposition of Thin Film Heterostructures

Pulsed Laser Deposition of Thin Film Heterostructures

Thin films of Strontium Ruthenate have been grown on Strontium Titanate and Lanthanum Aluminate (100) substrates by pulsed laser deposition. X-ray diffraction results show that the films grown on the Strontium Titanate are amorphous and polycrystalline on the Lanthanum Aluminate. Resistances versus temperature measurements show that the films exhibit semiconducting characteristics. In addition to the growth of Strontium Ruthenate thin films, multilayer heterostructures of Terfenol-D thin films on polycrystalline Lead Titanate thin films were grown by pulsed laser deposition. By using a novel experimental technique called magnetic field assisted piezoelectric force microscopy it is possible to investigate the magnetoelectric coupling between the electrostrictive Lead Titanate and magnetostrictive Terfenol-D thin film. Upon examination of the produced thin films the phase and amplitude components of the piezoelectric signal experience changes in response to an applied in-plane magnetic field. These changes provide experimental evidence of a magnetoelectric coupling between the Terfenol-D and Lead Titanate layers.
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Long-pulsed Nd : YAG laser: does it give clinical benefit on the treatment of resistant telangiectasia?

Long-pulsed Nd : YAG laser: does it give clinical benefit on the treatment of resistant telangiectasia?

Recently, the laser machine emitting dual wavelength (595 and 1064 nm) was introduced. Pulsed dye laser works first on haemo- globin and it turned laser irradiated oxyhaemoglobin into methe- moglobin, which absorbs following Nd : YAG laser much effectively. The sequential delivery of 595 and 1064 nm wavelength was expected to bring synergistic effects on vessel treatment, reducing the required fluence of following Nd : YAG laser. 18,19 The split face study was conducted to compare the treatment effi- cacy of dual laser and pulsed dye laser or long-pulsed Nd : YAG laser alone on facial telangiectasia. 18 The diameter of targeted ves- sels was <0.6 mm, and the skin type of enrolled patients was I–III according to Fitzpatrick. 18 Pulse dye laser was irradiated first using
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Fundamental Architecture and Analysis of an Antimatter Ultra Intense Laser Derived Pulsed Space Propulsion System

Fundamental Architecture and Analysis of an Antimatter Ultra Intense Laser Derived Pulsed Space Propulsion System

Other laser derived space propulsion systems have been conceptually developed. The perspective by Winter- berg resembles the concept of the laser propelled light sail [26]. The laser propelled light sail uses a laser beam to provide propulsion [8]. Light imparts momentum to the sail, as photons constitute particles of light. The pro- posed sails functioning as receiver optics have diameters on the scale of 1000 km. Laser power requirements are on the scope of a continuous 1 PW power budget [17]. Such power requirements are at the capacity level of all of civilization [12]. In order to achieve the desired sub-relativistic velocities the propulsive laser beam must be focused on the sail target for years of duration. Although inherently encumbered with substantial geometric and power budget constrains, the laser powered light sail propulsion application has been published as a near term technology [34].
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NLC 800 Air-Cooled Argon-ion Laser

NLC 800 Air-Cooled Argon-ion Laser

The use of controls, adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure. The NLC 800 product line is a Class 3b & 4 - medium & high power laser whose beam is, by definition, a safety hazard. Avoid viewing the beam directly, or as reflected by a mirror or other polished surface. The 800 product line, when used in conjunction with compatible power supplies contains circuits that operate at dangerous voltages and current levels. Avoid touching high voltage terminals or components. Internal measurements and/or
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The Role of Using Ultra Short Pulsed Lasers in Determining Dynamical Dependent of Free Electron Density in the Skin Tissue for Treatment of Skin Cancer

The Role of Using Ultra Short Pulsed Lasers in Determining Dynamical Dependent of Free Electron Density in the Skin Tissue for Treatment of Skin Cancer

The great progress in laser treatment in clinical applications is primarily attributed to the rapid development of pulsed laser systems. The use of highly focused pulsed laser beam to modify and manipulate tissue medium for applications in molecular and cellular biophysics and biotechnology becomes more pervasive [1,2]. Ultrafast lasers output ultra-short pulses with pulse widths ranging from picoseconds down to femtoseconds. Short-pulse lasers have become greatly important in recent years for many technologies, including laser cleaning, and medical and biological applications. Applications include dissection or inactivation of cellular organelles and chromosomes with submicron spatial precision [3], and gene delivery through transient membrane disruption [4], to name a few. As the pulsed laser micro beam technologies continue to advance, the fundamental knowledge of laser- tissue interaction mechanisms is of vital importance and could provide a framework where in systematic investigation of novel pulsed micro beam techniques can be developed. The plasma-mediated ablation model has been employed to explain the optical breakdown phenomenon in the visible and near-infrared wavelength region, in which
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Hirsutism, What to do?

Hirsutism, What to do?

Hirsutism, excessive hair growth in women in a male pattern distribution, is the most common endocrine disorder in women and approximately 5 to 15% of the general population of women is reported to be hirsute. It causes profound stress in women. Polycystic ovary syndrome is the most common cause. However a woman could have normal menses, normal androgen levels but be hirsute (idiopathic hirsutism). Ferriman- Gallwey scale (F-G) is used for assessment of hairiness. The maximum score is 36 and a score over 8 is considered as a hirsuid state. As hirsutism is a symptom and not a disease it is important to find the underlying cause and exclude uncommon but serious causes. The aim of the medical treatment is to correct the hormonal imbalance and thereby stop further progress. Oral contraceptives (OCP) are recommended as first line treatment. Spironolactone is the first choice if there is indication for antiandrogen therapy. Antiandrogens should be combined with an OCP in women in child bearing age as antiandrogens are teratogenic. Photo-epilation or electrolysis is mostly needed in order to reduce the amount of hair. Multiple treatments are needed. Hair reduction with each session with photo-epilation is estimated to 15% to 30%. Medical therapy and laser or IPL should be combined for best result.
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Pulsed laser deposition of electronic materials

Pulsed laser deposition of electronic materials

the crystal quality o f the films. Deposition using the lower wavelength o f 248 nm results in a much reduced density o f particulates. High substrate tem peratures o f >500°C are beneficial in increasing the crystal quality. During the growth o f C e02 an amorphous layer o f CeO^ (1 < x < 2) is initially formed (within 50-60 Â) which is gradually developed into a highly oriented Ce02 structure. A low laser energy density (< 2 J/cm) results in a linear dependence o f deposition rate with laser fluence, while at higher laser energy densities a logarithmic dependence is obtained. A transition from the linear to logarithmic regime results in a reduced density of voids and particulates on the surface of the film. Deposition from a target with a smooth and flat surface was shown to reduce the density of particulates on the film surface, and particularly in the case o f ablation using the Nd:YAG laser the density o f larger particles (>1 |im ) could be reduced to zero. However, a target pre-ablated with the NdiYAG laser had a rougher surface when compared to a non-ablated target, while a target pre-ablated with the excim er laser generated a flatter surface. The deposition o f C e02 thin films on sapphire at a P02 of 2x10-^ mbar and a T, o f 500°C resulted in a (111) oriented film while a P02 o f 2x10-^ mbar and a T, o f 650°C resulted in a film that was (200) oriented. The lattice constant of Ce02 can be modified by the addition of elements such as La or Y. This was done by depositing a film from a target with composition: 60% C e02 and 40% La203, on top of an undoped Ce02 film. Deposition o f YBaCuO thin film s on Ce0 2 /Si resulted in a c-axis oriented film with no apparent traces o f interdiffusion ( an Auger or secondary ion mass spectroscopy depth profiling can be carried out to confirm this). A T^. of only =78 It was obtained which can be improved by optimising the growth of YBaCuO. The growth o f BiSrCaCuO on Ce02/Si resulted in intermixing when the NdiYAG laser was used for the deposition o f HTSC and buffer layers. A highly c-axis oriented BiSrCaCuO film with some missing peaks resulted when the excimer laser was used to deposit the HTSC and the buffer layers.
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<p>Effects of a single treatment with two nonthermal laser wavelengths on chronic neck and shoulder pain</p>

<p>Effects of a single treatment with two nonthermal laser wavelengths on chronic neck and shoulder pain</p>

The secondary ef fi cacy measure, neck and shoulder ROM, also showed improvement. Mean seated passive abduction improved 27.9 degrees on both sides, mean shoulder measurements in relaxed position improved 30.1 degrees on the right side and 28.5 degrees on the left side and mean neck ROM measurements improved 22.7 and 23.4 degrees for the right and left sides, respectively (Table 3). Overall, subjects achieved a mean 29.07% improvement in neck and shoulder ROM. Among subjects achieving individual treatment success, there was no addi- tional improvement in ROM outcomes. A comparison of clinical outcomes following treatment with the violet and red lasers vs the red laser alone is summarized in Table 4. The proportion of subjects who were “ Very Satis fi ed ” with an overall change in neck and shoulder pain increased from 41% at endpoint evaluation to 46% at 48 hrs post- procedure evaluation and 71% of subjects were “ Very Satis fi ed ” or “ Somewhat Satis fi ed ” (Table 5). One subject who did not achieve a ≥ 30% decrease in VAS scores
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