Nm In Range Research Articles

Abstract 2498: Melanoma cell -derived extracellular vesicles - immunomodulators of the tumor microenvironment

Abstract The role of extracellular vesicles (EVs) in tumor-stroma communication has been under extensive investigation, and their contribution to inflammation and immunosuppression, angiogenesis and metastasis has been demonstrated. However, the exact molecular mechanisms and the EV cargos responsible for mediating these effects are still partly unknown. In tumor microenvironment, macrophages are one of the most abundant cell types and they are composed of several distinct populations that share features of both pro-inflammatory (M1) and immunosuppressive (M2) macrophages. In this study, we investigated the effects of melanoma cell secreted EVs on macrophage polarization. In several cancers hyaluronan synthesis is elevated and overexpression of its producing enzyme, hyaluronan synthase 3 (HAS3), induces EV shedding from the plasma membrane. These HAS3 induced EVs contain a hyaluronan coat around the vesicles. To elucidate the effects of HAS3-induced EVs on target cells, THP1 monocytes were treated with EVs derived from EGFP-HAS3 overexpression MV3 melanoma cells, or from parental MV3 cells, and the expression of cytokines and other factors related in cancer -induced immune modulation was studied. EVs were isolated with ultracentrifugation and characterized with Nanoparticle tracking analysis (NanoSight NS300) and transmission electron microscopy. THP1 cells were activated with PMA for 48 h and thereafter cells were treated with either control EVs from MV3 cells or hyaluronan coated EVs from HAS3 overexpressing cells for 4-24 h. The expression of pro-inflammatory and immunosuppressive markers was studied with qPCR, and the effects on cell morphology with confocal microscopy. The size distribution of EVs derived from MV3 and HAS3-MV3 cells was relatively similar, being approximately 100-200 nm in range, while the particle concentration (/ml) was higher in samples derived from HAS3-MV3 cells. The expression of proinflammatory cytokines and chemokines, like IL-1β and IL-8, and immunosuppressive factors like TSG-6 and PD-L1 was elevated in macrophages treated with MV3 melanoma cell secreted EVs. The effect on expression of the studied factors was more obvious when cells were treated with hyaluronan coated EVs (HAS3-MV3 EVs). This indicates that either the hyaluronan coat around the EVs or their cargo is different compared to control EVs, which causes the effects. Inhibiting TLR4 receptor decreased the cytokine expression induced by HAS3-MV3 EVs, suggesting TLR4-mediated activation after HAS3-MV3 EV exposure. Our results suggest that melanoma cell derived EVs induce mixed M1/M2 polarization of THP1 monocytes. Citation Format: Sanna Marika Pasonen-Seppänen, Piia Takabe, Kirsi Kainulainen, Kaisa Mäki-Mantila, Riku Korkiamäki, Silvia Lopez Borrego, Taija Hukkanen, Niina Aaltonen, Kirsi Rilla. Melanoma cell -derived extracellular vesicles - immunomodulators of the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2498.

Betaine-based deep eutectic solvents mediated synthesis of zinc oxide nanoparticles at low temperature

Deep eutectic solvents (DES) are gaining popularity as a potential substitute for ionic liquids because of their lower cost and biodegradability. Betaine and phenol with melting points ∼300 °C and ∼43 °C, respectively, combine with a molar ratio of 1:2 to form a liquid at room temperature with a eutectic melting point of ∼20 °C. ZnO nanoparticles (NPs) were synthesized by using an eco-friendly and green synthesis method utilizing betaine-based DES at low temperature ∼80 °C for 2 h. X-ray diffraction analysis confirms the highly crystalline and single-phase formation of ZnO NPs with hexagonal-Wurtzite phase structure. The surface morphology of the ZnO NPs confirmed using scanning electron microscopic images revealing the mostly spherical in shape and some n-pointed stars and transmission electron microscopy images confirms that NPs are sub-100 nm in range. Also, energy dispersive X-ray results confirm the elemental composition of Zn K (∼8.6 keV) and O K (0.52 keV) to be ∼88.5 ± 1.7% and 11.5 ± 1.3%, respectively. Fourier transform infrared spectroscopy confirms the bands at 565 and 410 cm−1 is assigned to asymmetric stretching and bending vibrations of the Zn–O tetrahedron. Thermogravimetric analysis verified the thermal stability with phase purity, resulting in the formation of the single-phase crystalline ZnO NPs. UV–Vis absorption study confirms the bandgap of ∼3.1 eV. The high stability and dispersion of NPs in water confirms the interaction of DES molecules on the surface of the NPs with water. ZnO NPs incorporated in PVA thin films show strong UV–Vis absorption confirming use of these transparent thin films for UV-shielding applications. As far as we know, this study is unique, green, eco-friendly and cost-effective in that the authors were able to synthesize ZnO NPs from betaine-based DES.

Antimicrobial Properties of Strychnos phaeotricha (Loganiaceae) Liana Bark Secondary Metabolites at the Interface of Nanosilver Particles and Nanoencapsulation by Chitosan Transport Vehicles

In this study, Strychnos phaeotricha liana bark extract was used as a metabolite container both on the surface of metallic nanosilver and encapsulated by a chitosan polymer. The plant extract was able to reduce Ag+ into Ag0 efficiently, and the encapsulation rate was determined. The synthesized nanoderivatives were characterized using ultraviolet‐visible spectrophotometry (UV‐Vis), Fourier transform infrared (FTIR) spectroscopy, powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), and energy dispersive X‐ray (EDX) spectroscopy. These methods allowed for the determination of grain size, elemental mapping, form, and the presence of secondary metabolites at the interface of the silver. Antimicrobial properties and the oral acute toxicity profile of the generated nanoderivatives were assessed. Overall, the results show plasmon resonance bands 380–550 nm in range and metabolites at the interface of a spherical nanosilver grain of 13.5 nm diameter in size. The hybrid nanosilver and encapsulated chitosan exhibited significant antimicrobial activity against Salmonella spp, Echerichia coli, and Candida spp. Both nanosilver grains and nanocapsules were found to be nontoxic at the tested doses and are potential models to prevent microbial resistance.

Cationic cyclodextrin-adamantane poly(vinyl alcohol)-poly(ethylene glycol) assembly for siRNA delivery

In this research, the inclusion complex of cationic β-cyclodextrins (bcd) and adamantane (Ad) conjugated poly (vinyl alcohol), PVA, containing a poly (ethylene glycol) (PEG) polymer or Ad-PVA-PEG has been designed and synthesized as a siRNA carrier. Three different amino groups, i.e., putrescine, spermidine, and spermine substituted β-cyclodextrin (bcd1-3), were prepared. Their chemical structures were confirmed by 1H NMR and mass analysis. PVA was substituted by 4-hydroxy benzaldehyde connected to adamantane, which can fit in the β-cyclodextrin cavity. PEG was attached to the PVA chain. From the experiments, three cationic β-cyclodextrins can form the spherical nanoparticles with siRNA and Ad-PVA-PEG, as confirmed by 1H NMR and SEM analysis. The nanoparticles of Ad-PVA-PEG and bcd1-3 with various ratios have been studied, including the siRNA binding efficiency using gel electrophoresis. The nanoparticle size and zeta potential were investigated by using dynamic light scattering (DLS). It was found that the average size of the particles was less than 300 nm in range with the negative zeta potential buffer pH 7.4. In vitro evaluation showed that the siRNA nanoparticles knocked down GFP expression in A549 cells. The cytotoxicity test of siRNA nanoparticles show the same trend with Lipofectamine® 2000. Therefore, the self-assembly cationic bcd with Ad-PVA-PEG containing siRNA was a safe and efficient system for siRNA delivery.

A plug-and-play optical fiber SPR sensor for simultaneous measurement of glucose and cholesterol concentrations

A plug-and-play surface plasmon resonance (SPR) dual-parameter optical fiber biosensor is reported, in which Au film was firstly coated on the fiber surface for exciting SPR and the end half of the Au film was modified with Au nanoparticles to generate double SPR resonance valleys. For simultaneous detecting of glucose and cholesterol concentrations, modified P-mercaptophenylboronic acid (PMBA) and β-cyclodextrin (β-CD) were subsequently coated on the surface of sensor probe. Due to the cis-diol structure of glucose, it can interact with PMBA, leading to a red shift of one SPR resonant valley, whose maximum wavelength shift is 11.228 nm in the range of 0–1.7 mM glucose concentration. On the same time, the cholesterol molecules can realize the host-guest combination with β-CD, leading to a red shift of another SPR resonant valley, and the maximum wavelength shift is 18.893 nm in the cholesterol concentration range of 0–300 nM. The detection limits of the sensor to glucose and cholesterol are 0.00078 mM and 0.012 nM, respectively. The enhances the practical value of the dual-parameter sensor. Both theory and experiment results verify the feasibility of the “plug-and-play” sensor to measure the dual biomass of glucose and cholesterol with ultra-low detection limit and good selectivity. The proposed method provides a huge research value for the optical fiber sensor in multi-parameter measurement.

Determination of hypochlorite and bisulfite in water by bifunctional colorimetric sensor based on octupolar conjugated merocyanine dyes

In this study, we developed a bifunctional colorimetric fluorescent sensor based on three merocyanine structures for the detection of hypochlorite (ClO−) and bisulfite (HSO3−). In MeOH solution and under special conditions, this sensor shows high selectivity on fluorescence and UV–Vis spectra for the detection of ClO− and HSO3−, respectively. The sensor solution exhibits a strong red fluorescence emission at 638 nm, which was quenched and the blue color turned to purple pink rapidly upon the addition of ClO−. The mechanism of the detection of ClO− was confirmed via ESI-MS that the CC groups were induced to produce ethylene oxide and ethylene glycol derivatives by hypochlorite. The fluorescence emission at 638 nm in the concentration range of ClO− from 0 to 24 μM showed a good linear relationship (R2 = 0.9919), and the LOD of the sensor for ClO− was 0.42 μM. Interestingly, the sensor can also detect HSO3− in acid condition (pH less than 7.4). The blue shift of UV–Vis spectra of the solution of sensor were observed after addition of HSO3− and irradiation with visible light for about 4 min. The HSO3− concentration showed a good linear relationship (R2 = 0.9987) at 275 nm in the range of 12–42 μM, and thus its LOD was calculated to be 1.14 μM. Finally, the sensor has important value for detecting ClO− and HSO3− in tap water and lake water.

Green Synthesis of NiO Nanoparticle Using Ziziphus Spina-Christi Leaves Extract for Photocatalytic Methylene Blue Dye Degradation

In this presented work, ziziphus spina-christi leaves extract assisted green synthesise approach was used to prepare the NiO nanoparticle for UV light driven photocatalytic methylene blue (MB) dye degradation. Various analytical characterizations were used to understand the crystalline, structural, optical and morphological nature of the prepared nanoparticle. The prepared NiO nanoparticle have wide bandgap of 3.35 eV with average particle size of around 10–15 nm in range. Various environmental conditions and elemental trapping experiments were conducted to understand the factors affecting the MB degradation and main active species for the redox reaction. Hence, we hope that this green synthesise NiO would pave a new way for photocatalytic preparation and their environmental remediation application.

Enhanced Magneto-Optical, Morphological, and Photocatalytic Properties of Nickel-Substituted SnO2 Nanoparticles

In this present study, pure and Ni2+ (3, 7, and 10% mol.)-substituted SnO2 nanoparticles (NPs) were synthesized by sol-gel method. The prepared samples were characterized by powder XRD, FT-IR, FE-SEM, HR-TEM, EDX, UV-visible spectra, room temperature (RT) photoluminescence (PL) spectroscopy, and VSM techniques. XRD study revealed the polycrystalline tetragonal rutile structure of pure and Ni2+-substituted SnO2 NPs. Crystallite size of pure and Ni2+-substituted SnO2 NPs were found to be 26 to 34 nm in range. FT-IR study confirmed the presence of metal-oxide (M-O) bond vibrations for pure and Ni-substituted SnO2 NPs. FE-SEM, EDX, HR-TEM, and SAED pattern indicated that pure and Ni2+-substituted SnO2 NPs are well-defined formation of spherical-sized nanocrystallites, with diameter of about 10–40 nm of grain size. UV-Vis spectrum specified a sharp absorption peak ~ 425 nm representing the band to band transition. RT-PL study showed the peak ~ 467 nm for all samples, indicating the band gap of 2.65 eV. The higher value of Ms is found to be 0.0429 emu/g for Ni-substituted SnO2 NPs. Magnetic study revealed that the Ni-substituted SnO2 NPs presented ferromagnetism. Photocatalytic degradation (PCD) of methylene blue (MB) was analyzed using photo-catalytic reactor and obtained the maximum of PCD efficiency of 3% Ni-substituted SnO2 NPs under the visible light irradiation.

Formulation and Evaluation of Solid Lipid Nanoparticles of Olanzapine for the Treatment of Psychosis

Solid lipid nanoparticles (SLN) are typically spherical with an average diameter between 1 nm to 1000 nm in range. It is alternative carrier systems to tradition colloidal carriers, such as liposomes emulsions and polymeric micro and nanoparticles. Olanzapine (OZP) is an atypical antipsychotic agent which is used for treatment of Schizophrenia. Its oral bioavailability is around of 40%. OZP is a class II drug so it having low aqueous solubility. To overcome that problem and to increase its bioavailability, the solid lipid nanoparticles of olanzapine are prepared. Formulation batches designed by modifying type of surfactant ( Span 80, Tween 80), concentration of surfactant, Concentration of co-surfactant, type of lipid ( glyceryl monostearate, Stearic acid), Lipid concentration, speed of stirring and time of stirring using customised design of DOE. The SLN were prepared by high speed homogenization technique, and then characterized by particle size analysis, Drug entrapment efficiency and Drug diffusion study. A formulation containing GMS as a lipid stabilised with tween 80 as surfactant show good drug release, smaller particle size, as compared with other formulations with different lipid and surfactant. The present research findings indicate that OZP loaded solid lipid Nano particulate system for delivery of OZP with better efficacy with minimum adverse effects. Keywords: Olanzapine, SLN, GMS, high speed homogenization and DOE.

Structural, Morphological and Magnetic Properties of Cu2+ Doped ZnO Nanoparticles

Investigations on the structural, morphological and magnetic properties of Zn1-xCuxO (x=0.00 and 0.05) nanoparticles synthesized via simple and low cost sol-gel auto combustion technique. The synthesized samples were characterized by X-ray diffraction technique (XRD), and vibrating sample magnetometer (VSM). XRD pattern reveals the formation of single phase with hexagonal wurtzite structure of both the synthesized samples. It also confirms the sucssefully incorporation of dopant (Cu2+) into the ZnO lattice. The lattice parameter of Cu2+ doped ZnO is slightly greater than that of pure ZnO nanoparticles. The crystallite size of synthesized samples are as 21 and 19 nm in range. Magnetic study carried out by VSM at room temperature and shows the diamagnetic nature of pure ZnO nanoparticles. After the doping of Cu2+ ions in ZnO changes to ferromagnetic nature. The apperance of ferromagnetism due to the presence of free carriers induced by Cu2+ doped into ZnO nanoparticles.

Synthesis and Characterization of Pyrogallol Capped Silver Nanoparticles and Evaluation of Their In Vitro Anti-Bacterial, Anti-cancer Profile Against AGS Cells

The current research was aimed to carry out the synthesis and characterization of silver nanoparticles (AgNPs) from the Acacia nilotica leaf extract mediated compound pyrogallol (py). The py-AgNPs were evaluated for in vitro antioxidant, antimicrobial, and biofilm activities against Helicobacter pylori (H. pylori). Further, the apoptotic induction of human gastric adenocarcenoma (AGS) cells was also investigated. Characterization of py-AgNPs was evaluated by using Fourier transform infrared spectroscopy (FT-IR), High-resolution transmission electron microscopy (HR-TEM), Scanning electron microscopy (SEM), Zeta potential, dynamic light scattering (DLS), X-ray diffraction (XRD) and UV–visible spectrometry. The average size of py-AgNPs was 22.68–55.16 nm in range, confirmed by HR-TEM. The clear H. pylori biofilm and bacterial inhibition were observed by increasing the concentration. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on AGS cells were revealed that the increasing py-AgNPs level, significantly decreases the cell viability by increased apoptosis. The cell cycle arrest was observed. These results indicate that py-AgNPs have a vital function as an anti-H. pylori and anti-gastric cancer inhibitor and could be further used in the development of nanomedicines to counter lethal diseases.

Inclusion Biogenesis, Methods of Isolation and Clinical Application of Human Cellular Exosomes

Exosomes are a heterogenous subpopulation of extracellular vesicles 30–150 nm in range and of endosome-derived origin. We explored the exosome formation through different systems, including the endosomal sorting complex required for transport (ESCRT) and ESCRT-independent system, looking at the mechanisms of release. Different isolation techniques and specificities of exosomes from different tissues and cells are also discussed. Despite more than 30 years of research that followed their definition and indicated their important role in cellular physiology, the exosome biology is still in its infancy with rapidly growing interest. The reasons for the rapid increase in interest with respect to exosome biology is because they provide means of intercellular communication and transmission of macromolecules between cells, with a potential role in the development of diseases. Moreover, they have been investigated as prognostic biomarkers, with a potential for further development as diagnostic tools for neurodegenerative diseases and cancer. The interest grows further with the fact that exosomes were reported as useful vectors for drugs.

Biosynthesized silver nanoparticles using Bacillus amyloliquefaciens; Application for cytotoxicity effect on A549 cell line and photocatalytic degradation of p-nitrophenol

The present study reports the biosynthesis of silver nanoparticles (AgNPs) using Bacillus amyloliquefaciens MSR5. The cellfree supernatant of B. amyloliquefaciens acted as a stabilizing agent for the synthesis of AgNPs. The synthesized AgNPs were characterized using UV-vis spectrophotometer, PXRD, FTIR, SEM-EDX, DLS, and TEM. TEM image showed the spherical shape of the biosynthesized AgNPs and it was found to be 20-40 nm in range. In this study, the AgNPs were prepared by ultrasonic irradiation. The stability of the AgNPs was found to be -33.4 mV using zeta potential. The catalytic 4-nitrophenol (4-NP) degradation by AgNPs was examined under solar irradiation and furthermore, the effects of several degradation parameters were studied. The biosynthesized AgNPs exhibited a strong chemocatalytic action with a comprehensive degradation (98%) of 4-NP to 4-aminophenol (4-AP) using NaBH4 within 15 min. In addition, MTT assay was performed to evaluate the cytotoxicity of the biosynthesized AgNPs (10 – 200 μg). The results have shown that the AgNPs exhibited significant activity on A549 cells, which was dosedependent. The study elucidates the AgNPs synthesized using cellfree culture supernatant can be used for the elimination of hazardous pollutants from wastewater.

Electro Polymerization of o-Phenylenediamine Using Palladium Nanoparticles Coated Fabricated TiO2 Nanotubes Modified Glassy Carbon Electrode

Fabricated titanate nanotubes (f-TNT) are prepared by chemical deposition method using linen fiber. The f-TNTs is fabricated by TiO2 nanoparticles, the each TiO2 nanoparticles diameter has 80-100 nm in range. The Pd0 nanoparticle was coated on the surface of the f-TNT by chemical reduction method, using NaBH4 as reducing agent. The prepared Pd/f-TNTs characterized by FT-IR, FE-SEM and HRTEM, the result shows that the f-TNT diameter is 1500 nm and Pd nanoparticles range in 20-50 nm. The Pd/f-TNT nanocomposite modified glassy carbon (GC) electrode shows quasi irreversible redox behaviours in cyclic voltammeter. Those Pd/f-TNTs modified electrode is utilized for electrochemical polymerization of o-phenylenediamine in acid medium.

Novel Ca2GdTaO6:Mn4+,M (M = Li+, Na+, K+, and Mg2+) red phosphors for plant cultivation light-emitting diodes: Synthesis and luminescence properties

Recently, Mn4+-activated red phosphors are becoming potential color converters for application in indoor plant cultivation light-emitting diodes, owing to their satisfactory luminescence properties as well as low cost. Herein, novel Mn4+-activated double perovskite-type Ca2GdTaO6 phosphors have been synthesized by a high-temperature solid-state reaction method in air, which exhibited a broad excitation band with two peaks locating at 355 nm and 496 nm in range of 250–600 nm and had an intense red emission peaking at 676 nm due to Mn4+:2Eg→4A2g spin-forbidden transition ranging from 650 to 750 nm under 355 nm excitation. Concentration-dependent luminescence properties were studied. The optimal Mn4+ doping concentration in Ca2GdTaO6 host was 0.004, and the concentration quenching mechanism was determined to be a dipole-dipole interaction among Mn4+ ions. Furthermore, the Ca2GdTaO6:0.004Mn4+ phosphor possessed the internal quantum efficiency up to 33% when excited at 355 nm. Besides, the decay lifetimes of Ca2GdTaO6:Mn4+ presented a reasonable downward trend with increasing Mn4+ concentration. In addition, the effect of charge compensation (co-doping of Li+, Na+, K+, and Mg2+ ions) on the luminescent properties of Ca2GdTaO6:Mn4+ phosphors was also investigated.

Standard manufacturing procedure of Teekshna lauha bhasma

BackgroundLauha bhasma is one of the herbo-metallic preparations used in Ayurveda, a traditional Indian system of medicine for treating various ailments such as anemia, diarrhea, hyperlipidemia and diabetes. ObjectiveTo establish standard manufacturing procedure of Teekshna lauha bhasma and analyze its physico-chemical properties. Materials and methodsThe preparation of T. lauha bhasma (calx of iron [Fe] turning) involves samanya shodhana, vishesha shodhana followed by bhanupaka, sthalipaka and putapaka with Triphala kwatha as a medium under temperature of 650 °C in electric muffle furnace (EMF) and maintained for 1 h. T. lauha bhasma were subjected to different physico-chemical characterization using X-ray fluorescence spectrophotometer and scanning electron microscopy. Results and discussionThe results suggest that these steps are necessary to obtain a good quality of bhasma and also make it acceptable for trituration during Bhasmikarana process. It is found that T. lauha bhasma was prepared properly in 20 puta at a temperature of 650 °C. The particle size of 20 puta T. lauha bhasma is 100–500 nm in range. ConclusionPharmaceutical procedures given in Ayurvedic texts are necessary to prepare pakwa jambu phala varna T. lauha bhasma that complies with all the classical bhasma pariksha and modern analytical parameters in 20 puta at a temperature of 650 °C maintained for 1 h in EMF.

General Parametrization of Persisting Long-Range Nanoscale Phenomena in Force Measurements Emerging under Ambient Conditions

Advances in quantification of nanoscale forces are mainly focused on repulsive forces, the sample’s stiffness, and related parameters such as deformation. The reactivity and chemistry of the surface however depends on longer range forces that are prevalent in ambient conditions and control functional surfaces. Suitable models and appropriate parametrization of this range, however, are still emerging. Here, we define and employ metrics to parametrize long-range forces and experimental observables in dynamic atomic force microscopy and force measurements in a general way even when suitable physical models are lacking. We find that plateaus in the attractive part of the force that can be of more than 1 nm in range are a general characteristic of surfaces exposed to the ambient environment. These plateaus can be identified directly from force measurements or indirectly from computationally low-cost parameters that we define here. We further demonstrate that the defined metrics can be employed for rapid discri...

Preparation and Characterization of Ag Doped Mn<sub>2</sub>O<sub>3</sub> Nanomaterial for CO Oxidation

Nano-sized silver doped Mn2O3 was synthesized by starch assisted co-precipitation technique. The prepared samples were tested for CO oxidation reaction. Ag doped Mn2O3 sample was found to show higher activity then pristine Mn2O3. XRD patterns authenticate the formation of Mn2O3 phase. Electron microscopy images show that the particles are in nano-sized, agglomerated and 40 - 70 nm in range. Thermal analysis data indicates the phase change from Mn2O3 to Mn3O4 beyond 950 °C. Magnetic susceptibility data indicates the paramagnetic nature of these samples. Electrical resistivity measurement shows that these samples are semiconductors. Keywords: Mn2O3; Ag doped Mn2O3, Co-precipitation, Electron microscopy, Thermal analysis, Carbon monoxide oxidation.

Microwave Assisted Reflux Synthesis and Characterization of Magnetic Fe<sub>3</sub>O<sub>4 </sub>Micro Bubbles Embed in Nano Particles

Magnetic Fe3O4 nanobubbles surrounded by nanoparticles are prepared by adopting microwave assisted reflux method. The nanomagnetic particles surrounded by small beads like particles are fabricated by irradiating the prepaperd sample solutions by microwave radiations coupled with reflux method simultaneously at 90°C for 45 mins. The characterization of the prepared Fe3O4 particles are carried out by using x ray diffraction, scanning electron microscopy and transmission electron microscopy. The instrumentations shows the morphology that is thick walled bubble like with approximate diameter of about 300 nm to 400 nm surrounded by small nanoparticles of 5 nm to 30 nm in range. The particles are bubbles like and some broken bubbles showed that these might be hollow from inside.

Thickness dependence oscillations of transport properties in thin films of a topological insulator Bi91Sb9

The dependences of the electrical conductivity, Hall coefficient, magnetoresistance, and Seebeck coefficient on the thickness d (d = 15–400 nm) of the topological insulator Bi91Sb9 thin films grown on mica substrates were obtained at room temperature. In addition to the oscillations with a period Δd = (105 ± 5) nm in the thickness range d = 100–400 nm which are attributed to the quantization of the semiconductor electron energy spectrum, oscillations with a period Δd = (8 ± 2) nm in the range d = 15–60 nm were also revealed. It is suggested that the existence of the high-frequency oscillations in the thin films may be connected with the quantization of the metallic surface states energy spectrum.