جستجوی مقالات مرتبط با کلیدواژه « semiconductor » در نشریات گروه « پزشکی »

Photocatalysis process is widely investigated for removal of various pollutants from water and wastewater. ZrO2 is a common metal oxide semiconductor with excellent optical properties, non-toxicity, stability in acidic and alkaline media, and high thermal stability. The appropriate potential levels of conduction and valence bands of this metal oxide are among its other desirable properties. Therefore, ZrO2 is a promising candidate for the photocatalysis process and the photocatalytic degradation of various pollutants in water treatment. However, the pure ZrO2 is not efficient enough due to its high recombination rate of electron-hole pairs and wide bandgap. The combination of ZrO2 with other semiconductors is an effective strategy to tackle these disadvantages. This not only delays the recombination of electron-hole pairs but also reduces the bandgap of the composite, improving light absorption in the visible region in many cases. In the photocatalysis process, noble metal-free materials have been gaining traction, as they are inexpensive and eco-friendly, and therefore applicable for large-scale industrial uses. This paper reports a review of the combination of noble metal-free materials with ZrO2 and its effects on optical properties, surface, and water treatment efficiency. This study also reviews several complex mechanisms of active species generation and pollution degradation through ZrO2-based photocatalysts. The photocatalytic activities of photocatalysts are then analyzed under different experimental conditions. Finally, a few suggestions are made for future research avenues, the systematic design of ZrO2-based photocatalysts, and the synthesis of photocatalysts activated in visible-light with high efficiency in the removal of pollutants from the water.

Diode lasers can be used in the treatment of periodontal diseases as they have an anti‑bactericidal effect, and regulate oral tissue inflammatory responses. This study aimed to evaluate the adjunctive effects of Diode 940 nm laser on mechanical periodontal debridement.

In this split‑mouth single‑blind randomized clinical trial, 12 patients were selected. Forty‑four oral segments were enrolled in the scaling and root planing (SRP) group and SRP + Laser group with a 1:1 allocation ratio following a simple randomization procedure (coin flip). Clinical parameters (pocket depth, clinical attachment loss [CAL], and bleeding on probing [BOP]) were measured at baseline. After the SRP, a 940 nm Diode laser (1 Watt power and continuous wave mode) was used in the SRP + Laser group as an adjunctive treatment. The clinical parameters were remeasured 2 months posttreatment. Statistical analysis was carried out using an unpaired t‑test with a 5% significant level by SPSS.

Although all clinical parameters had more improvements in the SRP + Laser group, the differences were not significant between the two study groups (P > 0.05). Only in individual tooth evaluations, CAL changes in first and second premolars and BOP changes in second premolars show statistically significant improvement in the SRP + L group compared to the SRP group (P < 0.05).

Using diode 940 nm laser as an adjunctive treatment for SRP may be helpful and be suggested for periodontal treatment.

This study assessed the effect of a high-intensity laser on Candida albicans colony count.

This in vitro, experimental study was conducted on standard-strain C. albicans (ATCC18 804). Seventy-two samples with two different concentrations of C. albicans (104 cells/mL and 106 cells/mL) were randomly assigned to three groups of control, laser and nystatin. Each group included 12 samples from each concentration. In the nystatin group, 10 cc of nystatin suspension was added to the samples and mixed for 30-60 seconds. In the laser group, the Ga-Al-Ar diode laser with a 940-nm wavelength and 2-W power was irradiated to the samples with 0.4 mm tip diameter in non-contact mode (1-mm distance) at a speed of 1 mm/s. The suspensions in the three groups were cultured on the Sabouraud dextrose agar culture medium and incubated at 37°C for 24 hours. The number of C. albicans colonies was then counted and reported. The three groups were compared by ANOVA and Tukey’s test (alpha = 0.05).

In both concentrations, the mean colony count in the nystatin group was significantly lower than that in the control (P < 0.05) and laser (P < 0.05) groups. The mean colony count in the laser group was significantly lower than that in the control group (P < 0.05).

The high-intensity laser with a 940-nm wavelength and 2-W power in non-contact mode can significantly decrease the C. albicans colony count in vitro, but its effect is lower than that of nystatin.

Nanotechnology has become one of the most widely used technologies in translational research and may significantly impact the future of healthcare. Because of their distinctive physicochemical characteristics, nanoparticles (NPs) have diverse applications in all areas of science including biomedicine, agriculture, biolabeling, catalysis, electronics, sensors, and fiber optics. Recently, green synthesis technology, as a reliable and eco-friendly method, has been taken into consideration for synthesizing a wide range of nanomaterials of desired sizes, shape, and functionalities. In this regard, zinc selenide nanoparticles (ZnSe-NPs) as a semiconductor nanostructure with low toxicity and high luminescence features have potential applications in different research fields like optoelectronic devices, laser solar cells, and, particularly in medical and biological sciences. ZnSe NPs can be synthesized by various chemical methods, including sol-gel, solvothermal, hydrothermal, wet chemical, and green and biological synthesis approaches. In this study, we have reviewed the green chemical or biological ZnSe nanoparticles synthesis as eco-friendly methods. Also, we have discussed the biological applications of ZnSe nanoparticles, including antibacterial activity, cytotoxicity effect, biomedical imaging and, drug delivery.

Here in the present study, we report the synthesis of ZnO nanoparticles, ZnO/CuO(3%), ZnO/CuO(5%), and ZnO/CuO(10%), nanocomposites using simple precipitation method with variation of CuO content and the activities of prepared samples were investigated for degradation of Brilliant Cresyl Blue (BCB) dye under visible light conditions in aqueous solutions. The structural, morphology, optical and compositional characteristics of fabricated samples were characterized by using Fourier Transform Infra-Red (FTIR) Spectroscopy, Field Emission Scanning Electron Microscopy combine electron dispersive spectroscopy (FESEM-EDS) and UV-vis spectroscopy. FESEM images show that ZnO nanoparticles are polygon like shape structure while ZnO/CuO have polygon and sheet shape structures. XRD patterns reflect the high crystalinity and purity of samples. The optical band gap values determined from optical absorption method indicate that band gap energy decreased with increase of CuO content in ZnO. The catalytic efficiency of the ZnO/CuO hybrid nanocomposite was observed to be higher than the ZnO nanoparticles under similar reaction conditions, 97.30% of Brilliant Cresyl Blue (BCB) dye was degraded after 100 min of irradiation of visible light radiation using the ZnO/CuO(5%) hybrid nanocomposite. The higher efficiency of ZnO/CuO compare to ZnO may be due to increased surface area and decreased band gap energy. The kinetic study of the photoctalytic degradation displayed that hybrid ZnO/CuO degrdaded dye with high rate constant k (34.88x10-3 min -1) compare to ZnO (k, 7.00x10-3 min-1). The optimization of reaction conditions of photodegradation process were attained by the variation in reaction factors such as pH, dye concentration, catalyst amount, and reaction time.

Giant cell fibroma (GCF) is a relatively rare lesion in the oral cavity. Despite having unique microscopic features, it can be easily misdiagnosed clinically as any common hyperplastic lesion. This report presents a case of a 21-year old male with a lesion involving the papilla between the mandibular central incisors. The lesion was excised completely under topical anesthesia using a 980 nm diode laser. On histopathological examination of the excised tissue, no thermal damage or any other alteration was observed, while the features were suggestive of GCF. Healing of the gingiva was uneventful and without any signs of recurrence. Apart from the widely known advantages of the diode laser, it also appears to maintain the integrity of biopsy specimens, if used with appropriate settings. This advantage may play a vital role in the biopsy of rare lesions where the diagnosis is entirely based on accurate histopathological examination.

Au nanoparticles (AuNPs) exhibit very unique physiochemical and optical properties, which now are extensively studied in a range of medical diagnostic and therapeutic applications. AuNPs can be used for cancer clinical treatment with minimal invasion. On the other hand, curcumin is a polyphenol derived from turmeric which is used for medical purposes due to its anti-cancer, anti-microbial, anti-oxidant and anti-inflammatory properties. Despite these potential properties of curcumin, its usage is limited in medicine due to low solubility in water. Conjugation of curcumin to AuNPs (Au-Cur nanostructure) can be increasing its solubility. Photo-thermal therapy (PTT) is a novel kind of cancer treatment which involves two major components: laser and photo-thermoconversion agents.

Here, diode lasers emitting 808 nm and 650 nm were utilized as light sources, and synthesized Au-Cur nanostructure was applied as a photo-thermo conversion agent. UV-vis absorbance spectroscopy and dynamic light scattering (DLS) were applied to study the maximum absorption of particles, size stability of the samples and their zeta potential. The synthesized Au-Cur nanostructure under irradiation of laser is used for PPT on 4T1 cells. The cytotoxicity activity of Au-Cur nanostructure and laser irradiation on 4T1 cells was evaluated by MTT assay.

Synthesized Au-Cur nanostructure showed λmax at 540 nm and a mean hydrodynamic diameter of 25.8 nm. 4T1 cells were exposed to an 808 nm diode laser (1.5 W cm2, 10 min) in the presence of different concentrations of Au-Cur nanostructure. Next, 4T1 cells with Au-Cur nanostructure were exposed to diode laser beam (650 nm, 1.5 W cm2) for 10 min. The results revealed that Au-Cur nanostructure under laser irradiation of 808 nm more decreased cell viability of 4T1 cells compared to laser irradiation of 650 nm.

It was concluded that combining an 808-nm laser at a power density of 1.5W/cm2 with Au-Cur nanostructure has a destruction effect on 4T1 breast cancer cells in vitro experiments compared to laser irradiation of 650 nm.

Hexagonal-structured zinc oxide (ZnO) is a semiconductor material with various industrial and cosmetic applications. Some of the main limitations of ZnO are aggregation, poor dispersibility, and wide energy gap, which limit its efficiency in some applications. The present study aimed to synthesize tungsten (W)-doped ZnO nanostructures using a hydrothermal method and characterize the particles to discover their application potency in various fields. To do so, 0.5%, 1.0%, and 2.0% of tungsten oxide (WO) were incorporated into the structure of ZnO, and the properties of the particles were determined via SEM, XRD, FTIR, AFM, DLS, and UV-Vis spectroscopy and zeta potential analysis. According to the obtained SEM images and XRD patterns, the prepared particles possessed hexagonal, non-aggregated structures. Furthermore, the UV-Vis spectra and AFM micrograms indicated that the doping of the ZnO nanostructures with tungsten caused a spectral shift in the absorbance of ZnO nanoparticles from the UV region to the visible light spectrum, increasing their relative roughness. According to DLS analysis, doping decreased the particle size of ZnO. In general, our findings demonstrated that the doping of ZnO nanostructures with tungsten could promote their efficiency and applicability in the treatment of environmental pollutants

Diode laser irradiation has recently shown promising results for treatment of gingival pigmentation. This study sought to compare the efficacy of 2 diode laser irradiation protocols for treatment of gingival pigmentations, namely the conventional method and the sieve method.
In this split-mouth clinical trial, 15 patients with gingival pigmentation were selected and their pigmentation intensity was determined using Dummett’s oral pigmentation index (DOPI) in different dental regions. Diode laser (980 nm wavelength and 2 W power) was irradiated through a stipple pattern (sieve method) and conventionally in the other side of the mouth. Level of pain and satisfaction with the outcome (both patient and periodontist) were measured using a 0-10 visual analog scale (VAS) for both methods. Patients were followed up at 2 weeks, one month and 3 months. Pigmentation levels were compared using repeated measures of analysis of variance (ANOVA). The difference in level of pain and satisfaction between the 2 groups was analyzed by sample t test and general estimate equation model.
No significant differences were found regarding the reduction of pigmentation scores and pain and scores between the 2 groups. The difference in satisfaction with the results at the three time points was significant in both conventional and sieve methods in patients (P = 0.001) and periodontists (P = 0.015).
Diode laser irradiation in both methods successfully eliminated gingival pigmentations. The sieve method was comparable to conventional technique, offering no additional advantage.

Fluoride therapy is important for control and prevention of dental caries. Laser irradiation can increase fluoride uptake especially when combined with topical fluoride application. The objective of this study was to compare the effects of CO2 and diode lasers on enamel fluoride uptake in primary teeth.
Forty human primary molars were randomly assigned to four groups (n=10). The roots were removed and the crowns were sectioned mesiodistally into buccal and lingual halves as the experimental and control groups. All samples were treated with 5% sodium fluoride (NaF) varnish. The experimental samples in the four groups were irradiated with 5 or 7W diode or 1 or 2W CO2 laser for 15 seconds and were compared with the controls in terms of fluoride uptake, which was determined using an ion selective electrode after acid dissolution of the specimens. Data were analyzed by SPSS version 16 using ANOVA treating the control measurements as covariates.
The estimated amount of fluoride uptake was 59.5± 16.31 ppm, 66.5± 14.9 ppm, 78.6± 12.43 ppm and 90.4± 11.51 ppm for 5W and 7 W diode and 1W and 2 W CO2 lasers, respectively, which were significantly greater than the values in the conventional topical fluoridation group (P The results showed that enamel surface irradiation by CO2 and diode lasers increases the fluoride uptake.

 

Liposuction nowadays is the most popular way of weight loss and body contouring. It is a mechanical procedure to reduce fat through the back-and-forth movement of a heavy metal called cannula. The thick cannula, essential for efficient fat removal and subsequent suctioning, causes some undesirable effects such as bruise, scars, heavy blood loss, skin laxity and long-run recovery. While, the new method of liposuction using a 100-300 µm fiber laser inserted into a thin cannula of 1 mm diameter causes less distress and bleeding. Simultaneous interaction between laser radiation and tissue causes faster skin tightening and coagulation of small blood vessels.

The study aimed at evaluating the effects of these highly important parameters of lipolysis operations.

In this study, penetration depth and tissue heating following laser irradiation with a 980 nm diode laser were investigated. This laser is different from 1064 nm Nd:YAG in terms of absorption and scattering coefficient. Hence, dissimilar results for beam penetration and tissue heating were expected. Monte Carlo method was used to simulate radiation (photons) propagation in tissues. Using such simulation can be useful in evaluating penetration depth, absorption, scattering and reflection of the photon within the tissue and across the tissue borders. Temperature rise was simulated using Comsol Multiphysics software.

The simulation results showed that the penetration depth and temperature rise of 980 nm wavelengths were different from those of 1064 nm wavelength. It appeared that 1064 nm wavelength penetrated to deeper layers of tissue compared with 980 nm. Moreover, temperature rise during 1064 nm irradiation led to temperature increase in allowable ranges. The findings proved the reason why 1064 nm wavelength are commonly used in laser lipolysis in comparison with 980 nm wavelength.

The simulation indicated that temperature rise in 980 nm wavelength was 70.802 ℃, which was higher than that of 1064 nm wavelength. Therefore, 980 nm laser can leave unwanted negative effects on tissues including hyperthermia.