thin SiO/sub 2/

Top PDF thin SiO/sub 2/:

Antireflective Properties of Nano-Structured CeO 2 and CeO2 SiO 2 Composite Thin Films

Antireflective Properties of Nano-Structured CeO 2 and CeO2 SiO 2 Composite Thin Films

From the spectra, it can be clearly inferred that, amongst all other volume ratios, the thin film volume ratio of 1:2 showed minimum reflectance of only 3% in visible wavelength region, much lower than the reflectance of the substrate and exhibits a high transmittance of 94%. Hence, this composite has been further optimized with respect to thickness so as to get a minimum reflectance of 1.08% at a wavelength of 600 nm as shown in Figure 5.

5 Read more

Study of Iridium (Ir) Thin Films Deposited on to SiO2 Substrates

Study of Iridium (Ir) Thin Films Deposited on to SiO2 Substrates

Ir optical constants provided by other sources, taken on different sample forms (either bulk or thin films), and under different ambient conditions, can be found in the literature Palik's handbook in particular [15,16]. There are significant differences or inconsistencies, which are likely due to different surface roughnesses on samples evaluated in each case. Qualitatively, Palik's Ir optical constants agree with ours fairly well; quantitatively, however, they have lower values in both n and k, which, generally, suggests an unaccounted surface roughness. A simulation was thereof conducted to see if this was the case here. By adding ~4.1 nm surface roughness, we were able to match Palik's values based on our reported optical constants. In view of all of this, we believe the present work represents the best optical constants available for intrinsic Ir material, and cover the widest spectral range. Listed in Table 2 are the as-determined Ir optical constants at a few selected wavelengths. (There are slight differences among the five samples studied, and the optical constants for sample No. 2 are presented in Table 2 since they are the ones lying in between.)
Show more

8 Read more

Vancomycin-modified Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>@Ag microflowers as effective antimicrobial agents

Vancomycin-modified Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>@Ag microflowers as effective antimicrobial agents

A newly developed Van/Fe 3 O 4 @SiO 2 @Ag microflower with enhanced antibacterial activity is experimentally and theoretically presented in this study. The obtained microcomposite comprised three parts: a submicron-scale magnetic core to provide sufficient magnetic response property, a flower-like Ag shell to build highly active areas for Ag ion release and bacterial contact, and an ultrathin vancomycin layer to bind to the bacterial cell wall and increase the cell membrane permeability. The detailed nanostructures of the products were characterized by HRTEM, SEM, EDX, XRD, and elemental mapping analyses. The Van/Fe 3 O 4 @SiO 2 @Ag microflowers can rapidly and effectively kill both E. coli and MRSA at low concentrations. The killing efficiency can be increased to a high level. The MIC of the enhanced effect of the Van/ Fe 3 O 4 @SiO 2 @Ag microflowers decreased by ∼ 60% for E. coli and 63.5% for MRSA compared with that using only Fe 3 O 4 @SiO 2 @Ag microflowers. Thus, we think the effectiveness of vancomycin-modified Fe 3 O 4 @SiO 2 @Ag microflowers against resistant strains such as MRSA pro- vides a very simple but highly efficient strategy to combat drug-resistant bacterial infections. Moreover, the magnetic property renders the Van/Fe 3 O 4 @SiO 2 @Ag microflowers to be facilely controlled by an orientation magnetic field after antibacterial behavior. The recovered products can then be reused many times. We further demonstrated that the antimicrobial effect of the fabricated Van/Fe 3 O 4 @SiO 2 @Ag microflower was maintained at no less than 90% after cycling for five times, indicating the high stability of the product. Hence, the Van/Fe 3 O 4 @SiO 2 @Ag microflowers are potential effective and recyclable antibacterial agent for medical and environmental applications.
Show more

18 Read more

Analysis of Optical Properties of SiO2 Thin Films for Various Thicknesses and Substrate Material Using Matlab Code

Analysis of Optical Properties of SiO2 Thin Films for Various Thicknesses and Substrate Material Using Matlab Code

Silicon oxide ( ) Thin films are the most extensively studied among different deposited materials. Because of their technological importance as dielectric protective layers in semiconductor layers, integrated circuits, waveguides, and many other applications. However, high-quality films are required for these applications. has many interesting properties that make it suitable for thin film applications [1]. SiO 2 thin films have wide applications in the biomaterial

6 Read more

Role of surface modification in zinc oxide nanoparticles and its toxicity assessment toward human dermal fibroblast cells

Role of surface modification in zinc oxide nanoparticles and its toxicity assessment toward human dermal fibroblast cells

modification, a charge reversal of - 20.7 mV was obtained from the thin SiO 2 /ZnO particles and - 41.5 mV from the thick SiO 2 /ZnO NPs. These loosely aggregated particles from the coating with SiO 2 showed a thin layer on the surface, with the finding that increasing the Si-to-Zn molar ratio increased covering-layer thickness from 2 to 7 nm. Upon close inspec- tion, thinly coated ZnO NPs with SiO 2 showed an uncovered core in some areas of the particle (Figure 1B). However, the thickly coated particles revealed a homogeneous layer around each particle, with complete covering with an SiO 2 shell (Figure 1C). In the EDX spectra of the bare and SiO 2 -coated samples (Figure 1, A’–C’), all characteristic peaks were well matched with their unique elements of Zn, O, and Si. The C and O peaks occurred due to the supporting substrate used for TEM sampling. And the increasing peak intensity of C and O along with Zn and Si occurred due to the ele- ments present in the nanoparticles. Furthermore, quantitative elemental analyses of the bare ZnO particles were compared with those of the surface-modified particles, listed in Table 2. A 0.68 wt% of silica was observed from the thin SiO 2 /ZnO NPs, whereas the thick SiO 2 /ZnO NPs indicated 3.34 wt%.
Show more

12 Read more

Corrosion Polarization Behavior of Al-SiO2 Composites in 1M and Related Microstructural Analysis

Corrosion Polarization Behavior of Al-SiO2 Composites in 1M and Related Microstructural Analysis

[20], and graphite [21] in several media have been conducted. Corrosion behavior is not only measured using electrochemical impedance spectroscopy (EIS) but also by potentiodynamic polarization from Tafel polarization curve and Tafel impedance plots. Those studies focused on the type of corrosive media with various concentrations and temperatures. Common corrosion products in aluminum-based materials are galvanic corrosion, pitting corrosion, and grain boundaries corrosion [22, 23]. The galvanic and pitting corrosions occurred in Al-Gr composites, and it was revealed that the addition of Gr (1-3%wt) increased the corrosion rate of the Al-Gr composites [11]. In addition, the concentration and temperature of NaCl as the corrosion medium enhanced the corrosion rates of 6061- SiC [17] and 6063-Al 2 O 3 [19].
Show more

9 Read more

Polyetherimide-grafted Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub> nanoparticles as theranostic agents for simultaneous VEGF siRNA delivery and magnetic resonance cell imaging

Polyetherimide-grafted Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub> nanoparticles as theranostic agents for simultaneous VEGF siRNA delivery and magnetic resonance cell imaging

the assessment of the magnetic properties and the sensitivity of the formulated nanoparticles, magnetic hysteresis loops were recorded using a magnetometer, and the two types of nanoparticles showed superparamagnetic behavior without magnetic hysteresis (Figure 5) at room temperature (about 300 K). PEI modification did not change the magnetic property of Fe 3 O 4 @SiO 2 nanoparticles. Their magnetization saturation value was ~ 4.4 emu/g, and no significant difference in the magnetization saturation value was observed for the Fe 3 O 4 @SiO 2 and Fe 3 O 4 @SiO 2 /PEI nanoparticles. Further- more, the magnetic targeting of nanoparticles was tested in water by placing a magnet near the glass bottle. Both the Fe 3 O 4 @SiO 2 and Fe 3 O 4 @SiO 2 /PEI were attracted toward the magnet within a very short period of time (Figure 5, inset). These data revealed their superparamagnetic nature, and the nanoparticles could also get to targeted locations under an external magnetic field.
Show more

13 Read more

In vitro and in vivo targeting imaging of pancreatic cancer using a&nbsp;Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>&nbsp;nanoprobe modified with anti-mesothelin antibody

In vitro and in vivo targeting imaging of pancreatic cancer using a&nbsp;Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>&nbsp;nanoprobe modified with anti-mesothelin antibody

A-MFS can be used as negative contrast material. A-MFS has good stability of dispersion as shown in Figure S1. X-ray photoelectron spectroscopy detected that A-MFS contain Fe, O, C, N, and Si, so the result shows Si and antibodies are coated on the nanoparticle. Fe 3 O 4 and SPIONs are most com- monly used for preparation of multifunctional nanoparticles due to their unique superparamagnetic features, high stabil- ity, and biocompatibility. The superparamagnetic behavior of SPIONs is essential for MRI. Each SPION acts as a small magnet; therefore, SPIONs display increased magnetization and respond rapidly to external magnetic field. After remov- ing the external magnetic field, magnetized nanoparticles are dissipated by a brief shaking. SPIONs shorten the tissue T2-weighted relaxation time to enhance tissue MRI contrast and, therefore, are widely used as T2 contrast agents. The high stability of SPIONs enables persistent circulation in the blood and accumulation in the target area. If the probe diameter exceeds 300 nm, they are phagocytosed by the reticuloen- dothelial system. They persist in the blood circulation and accumulate less in tissues. Silica is used as a surface modifier of nanoparticles due to its nontoxicity and stability. Fe 3 O 4 is sealed by SiO 2 coating to improve its biocompatibility. The silica coating provides binding sites for the anti-MSLN anti- body. Therefore, our team successfully synthesized the A-MFS probe with good magnetic properties and high stability.
Show more

13 Read more

Porous Se@SiO<sub>2</sub> nanospheres treated paraquat-induced acute lung injury by resisting oxidative stress

Porous Se@SiO<sub>2</sub> nanospheres treated paraquat-induced acute lung injury by resisting oxidative stress

Abstract: Acute paraquat (PQ) poisoning is one of the most common forms of pesticide poisoning. Oxidative stress and inflammation are thought to be important mechanisms in PQ- induced acute lung injury (ALI). Selenium (Se) can scavenge intracellular free radicals directly or indirectly. In this study, we investigated whether porous Se@SiO 2 nanospheres could alleviate oxidative stress and inflammation in PQ-induced ALI. Male Sprague Dawley rats and RLE-6TN cells were used in this study. Rats were categorized into 3 groups: control (n=6), PQ (n=18), and PQ + Se@SiO 2 (n=18). The PQ and PQ + Se@SiO 2 groups were randomly and evenly
Show more

10 Read more

Biological responses to core&ndash;shell-structured Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-NH<sub>2</sub> nanoparticles in rats by a nuclear magnetic resonance-based metabonomic strategy

Biological responses to core&ndash;shell-structured Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-NH<sub>2</sub> nanoparticles in rats by a nuclear magnetic resonance-based metabonomic strategy

was applied to investigate the metabolic consequences in rats following the intravenous adminis- tration of parent NPs of core–shell-structured nanoparticles, Fe 3 O 4 @SiO 2 -NH 2 (Fe@Si) NPs. Results: Alterations reflected in plasma and urinary metabonomes indicated that Fe@Si NPs induced metabolic perturbation in choline, ketone-body, and amino-acid metabolism besides the common metabolic disorders in tricarboxylic acid cycle, lipids, and glycogen metabolism often induced by the exogenous agents. Additionally, intestinal flora metabolism and the urea cycle were also influenced by Fe@Si NP exposure. Time-dependent biological effects revealed obvious metabolic regression, dose-dependent biological effects implied different biochemical mechanisms between low- and high-dose Fe@Si NPs, and size-dependent biological effects provided potential windows for size optimization.
Show more

16 Read more

Immobilized transferrin Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub> nanoparticle with high doxorubicin loading for dual-targeted tumor drug delivery

Immobilized transferrin Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub> nanoparticle with high doxorubicin loading for dual-targeted tumor drug delivery

to its superparamagnetic core; 2) Tf-receptor-targeting, by the Tf ligand on the outer layer; and 3) high drug loading efficiency (achieved using a modified multi-armed coupling reagent, PLGA), controllable by altering reactant proportions. Moreover, TfDMP exhibited a narrow particle size distribution and showed pH-dependent release characteristics. Compared with DOX-coupled nanoparticles without a Tf modification, there was enhanced uptake of TfDMP by TfR-expressing tumor cells, and a stronger cytotoxicity was observed. This investigation reveals an effective method for dual-targeted delivery of chemotherapeutic agents to tumors, with greater control, low carrier toxicity, and high efficiency.
Show more

9 Read more

SiO<sub>2</sub> nanoparticle-induced impairment of mitochondrial energy metabolism in hepatocytes directly and through a Kupffer cell-mediated pathway in vitro

SiO<sub>2</sub> nanoparticle-induced impairment of mitochondrial energy metabolism in hepatocytes directly and through a Kupffer cell-mediated pathway in vitro

be visible by TEM. This concentration of SiO 2 nanoparticles indicates either effective removal of these nanoparticles from the cytoplasm after diffusion through the membrane or their uptake via mechanisms involving incorporation of par- ticles into the membrane, eg, endocytosis. In contrast, some particles did not appear to be membrane-bound but were free within the cytoplasm. Notably, swollen mitochondria with vacuolization and reduced crests were found near the particles that were free within the cytoplasm (Figure 3B); this location indicated that these particles that were free within the cytoplasm might be responsible for the damaged mitochondrion. In addition, the disturbance of mitochon- drial structure might be correlated with release of ROS and subsequent activation of p53, Bax, and Bcl-2, which are involved in the mitochondrial-dependent apoptotic pathway in BRL cells. In the present experiments, we also observed the location of the micrometer SiO 2 nanoparticles in BRL cells, and most of these were taken up and accumulated in cells. However, damaged mitochondria could not be visual- ized by TEM (images not shown).
Show more

13 Read more

Structural Properties of (SnO<sub>2</sub>)<sub>1-x</sub>(ZnO)<sub>x</sub>Thin Films Deposited By Spray Pyrolysis Technique

Structural Properties of (SnO<sub>2</sub>)<sub>1-x</sub>(ZnO)<sub>x</sub>Thin Films Deposited By Spray Pyrolysis Technique

identified as the reflections from (100)*, (002)*, (101)*, (102)*,(110)* and (103)* planes of hexagonal ZnO phase with a lattice parameters of a= 3.2490 Å and c=5.2050 Å. The most prominent peak for the x = 1 was the reflection from the (002)*plane. The diffraction peaks corresponding to (100)*,(002)* and(101)* planes were sharp in comparison to those from (102)*, (110)* and (103)* planes.It is shown that the highest intensity is located at the directionality (002)* with a direction perpendicular to the base. This tendency in crystallization is attributed to the Drift model, which is called the Survival of the Fasted model. We assume that the process of nucleation takes more than one direction in the early stages of films growth; these trends begin to compete as they grow. The nuclei continue to grow faster, while the growth of the other nuclei stops. This explains the growth of ZnO films toward (002)* decomposition or sedimentation direction.It was observed that the granular size of the ZnO films was smaller than the granular size of the SnO 2 films, indicating
Show more

8 Read more

Porous Se@SiO<sub>2</sub> nanospheres attenuate ischemia/reperfusion (I/R)-induced acute kidney injury (AKI) and inflammation by antioxidative stress

Porous Se@SiO<sub>2</sub> nanospheres attenuate ischemia/reperfusion (I/R)-induced acute kidney injury (AKI) and inflammation by antioxidative stress

evaluated the damage caused to the outer medullary regions in each experimental group. Upon histological examination, the I/R group showed features typical of severe acute tubular damage, including extensive tubular necrosis, tubular dilata- tion, and loss of the brush border. Mice treated with Se@ SiO 2 had significantly lower H&E scores for tubular dam- age after I/R (P,0.05 vs I/R + saline) (Figure 4A and B). Moreover, as shown in the results, the I/R + Se@SiO 2 group exhibited less cellular apoptosis (P,0.05 vs I/R + saline), as detected by TUNEL staining (Figure 4E and F). NGAL protein, a biomarker of AKI, is known to accumulate in the blood and urine and can be detected in patients with AKI after only a few hours. 34 We found that the proportion of NGAL-
Show more

15 Read more

Enhanced cellular uptake of aminosilane-coated superparamagnetic iron oxide nanoparticles in mammalian cell lines

Enhanced cellular uptake of aminosilane-coated superparamagnetic iron oxide nanoparticles in mammalian cell lines

The results from this study may suggest that cancers with biological features similar to breast cancer MCF-7, MDA- MB-231 cells, and colon cancer HT-29 cells may be less amenable to certain types of targeted therapy, while cancers with biological features similar to cancerous cells HepG2, PC-3, and U-87 MG may be more responsive to these types of targeted therapy. This study shows that the U-87 MG glioblastoma cell line had SPIO@SiO 2 -NH 2 nanoparticle accumulation four times higher than other cell lines. It is possible that human glioblastoma may be particularly suited for SPIO@SiO 2 -NH 2 -mediated cellular imaging or targeted therapy.
Show more

12 Read more

Nanometer-thin TiO<sub>2</sub> enhances skeletal muscle cell phenotype and behavior

Nanometer-thin TiO<sub>2</sub> enhances skeletal muscle cell phenotype and behavior

ddH 2 O and treated with 0.2% aqueous phosphomolybdic acid for one minute. The cultures were then washed again with ddH 2 O and stained with Sirius red dye (Pfaltz and Bauer, Stamford, CT) dissolved in saturated aqueous picric acid (pH 2.0) at a concentration of 100 mg/100 mL for 90 minutes with mild shaking. The cultures were washed with 0.01 N hydrochloric acid for two minutes to remove all nonbound dye. Afterwards, 600 µ L of 0.1 N sodium hydroxide was added to dissolve the staining using a microplate shaker for 30 minutes at room temperature. The optical density of the solution was then measured using a spectrophotom- eter at 550 nm against 0.1 N sodium hydroxide as a blank. Additionally, to visualize collagen deposition, the above- mentioned protocol was employed. Instead of dissolving the stained dye, the cultures were dehydrated in a graded series of ethanol (50%–100%) followed by Xylene and examined using a confocal laser scanning microscope.
Show more

13 Read more

Enhancement of Optical Gain and Amplified Spontaneous Emission due to waveguide geometry in the conjugated polymer MEH-PPV

Enhancement of Optical Gain and Amplified Spontaneous Emission due to waveguide geometry in the conjugated polymer MEH-PPV

PPV/air asymmetric waveguides (AWGs). Symmetric WG fabrication is low-cost and does not require complex proc- essing or specialized equipment, thus offering an alternate route for effectively controlling the ASE characteristics of CP-based active WGs and edge-emitting distributed feed- back laser devices. Note that while ASE threshold reductions have recently been demonstrated using glass/indium-tin oxide (ITO)/SiO 2 /MEH-PPV/SiO 2 /Ag SWG structures, the

6 Read more

(HMDI). For the PU/SiO 2

(HMDI). For the PU/SiO 2

The mechanism involves in the incorporation of silica into the PU structure is given in the schematic reaction as shown in Figure 4. The extracted silica nanoparticles were surrounded by silanol (-OH) groups. Considering the rapid reaction between –NCO and –OH groups, these silanol groups can react with the terminal –NCO groups of the formed PU pre-polymer. The reaction between these two groups binds the PU pre-polymer to the SiO 2 particle, thus

5 Read more

Nanoparticle with PEG and SiO 2

Nanoparticle with PEG and SiO 2

bond and does not come from photocatalytic process. It can explain why sample with silica still shows good performances even though without UV irradiation. The same thing was explained from Guan e. al. that the decrease of contact angle is not shown significantly with SiO 2

6 Read more

Assessing the axonal translocation of CeO<sub>2</sub> and SiO<sub>2</sub> nanoparticles in the sciatic nerve fibers of the frog: an ex vivo electrophysiological study

Assessing the axonal translocation of CeO<sub>2</sub> and SiO<sub>2</sub> nanoparticles in the sciatic nerve fibers of the frog: an ex vivo electrophysiological study

As an indication of the proper physiological function of the nerve fibers of the isolated sciatic nerve, samples of the evoked CAP were digitized and stored in a computer every 30 minutes throughout the experiment, usually last- ing over 36 hours. The amplitude of the CAP was measured from baseline to peak and expressed as a percentage of the amplitude of the CAP after 1 hour equilibration of the nerve. The percentage values were expressed as mean and standard error mean. The outcomes of many trials using different nerves were averaged and plotted against time as the vitality curve, or the time–response curve. For the eight experiments in which the nerves were exposed to CeO 2 , the values of the CAP, measured every 30 minutes, were expressed as means and standard error mean and were used to plot the time–response curve. When required, data were analyzed by one-way analysis of variance (ANOVA) and Bonferroni’s post hoc tests. We determined signifi- cance using Student’s t-test or ANOVA, as appropriate (P,0.05).
Show more

8 Read more

Show all 10000 documents...

Related subjects