Luminescence properties of green emission of SiO2/Zn2SiO4:Mn nanocomposite prepared by sol–gel method

Green light emitting Mn²⁺ doped Zn₂SiO₄ particles embedded in SiO₂ host matrix were synthesized by a sol–gel method. After the incorporation of ZnO:Mn nanoparticles in a silica monolith using sol–gel method with supercritical drying of ethyl alcohol in two steps, it was heat treated in air at 1200 °C for 2 h in order to obtain the SiO₂/α-Zn₂SiO₄:Mn nanocomposites. The microstructure of phosphor crystals was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). XRD results indicate that the pure phase α-Zn₂SiO₄ with rhombohedral structure was obtained after thermal treatment at 1200 °C. The SiO₂/α-Zn₂SiO₄:Mn nanocomposites with a Mn doping concentration of 1.5 at% exhibit two broadband emissions in the visible range: a strong green emission at around 525 nm and a second one in the range between 560 and 608 nm. This nanocomposite with a Mn doping concentration of 0.05 shows the highest relative emission intensity. Upon 255 nm excitation, the luminescence decay time of the green emission of Zn₂SiO₄:Mn around 525 nm is 11 ms. The luminescence spectra at 525 nm (⁴T₁–⁶A₁) and lifetime of the excited state of Mn²⁺ ions-doped Zn₂SiO₄ nanocrystals are investigated.     

Foam droplet separation for nanoparticle synthesis

A novel approach to nanoparticle synthesis was developed whereby foam bubble bursting produced aerosol droplets, an approach patterned after the marine foam aerosol cycle. The droplets were dried to remove solvent, leaving nanometer-sized particles composed of precursor material. Nanoparticles composed of sodium chloride (mean diameter, 100 nm), phosphotungstic acid ( 55 nm), and bovine insulin ( 5–30 nm) were synthesized. Foam droplet separation can be carried out at ambient temperature and pressure. The ‘soft’ nature of the process makes it compatible with a wide range of materials.     

Nanoparticle-doped chiral nematic liquid-crystal composite and its effect in magnetic-response and electric-response flexible display

A composite system of Fe3O4 nanoparticle-doped chiral nematic liquid crystals (N*LC) with flexible display performance was proposed. Fe3O4 nanoparticle and the nanoparticle-doped N*LC composite were detailed prepared and investigated. The influence of nanoparticle doping amount and chiral compound content on the magnetic performance as well as electrical performance of the flexible device had been studied in detail. The most suitable N*LC composites for magnetic-driven display had been found. With the characteristics of simple preparation, good stability and high resolution, the Fe3O4 nanoparticle-doped N*LCs had promising applications for power-free magnetic-driven flexible LC paper or display board.     

Research on Ice Crystal Growth Inside the Vitrified Vs55 with Magnetic Nanoparticles During Devitrification by Cryomicroscopy

The effect of magnetic nanoparticles(mNPs) on the devitrification crystallization of typical vitrification solution Vs55 was systematically explored by differential scanning calorimetry(DSC) and cryomicroscope system. The results show tliat,(i) the mNPs coated by both carboxylic acid(CA) and polyethylene glycol(PEG) had little effect on the glass transition temperature(rg) of Vs55, but had significant effect on the devitrification transition temperature(7a) and devitrification enthalpy(Hrd),(ii) in the range of the devitrification area(-85- 0℃), the MNPs coated by CA can significantly accelerate the devitrification of Vs55 as the isothermal temperatures and the cooling rates increased, and the ice growth rate was 0.37 p.m/s at the isothermal temperature of-85 ℃, and was about 2.19 gm/s at -75℃. Also, the ice growth rates rose from 1.72 pm/s to 3.54 pm/s when the cooling rates were increased from 2 ℃/min to 100 ℃/min(at the isothennal temperature of -75℃),(iii) magnetic nanoparticles coated by both PEG and CA could promote the devitrification of Vs55, for instance, without any crystal growth inside Vs55 at the isothermal temperature of-80℃, but 1.04 and 2.31 gm/s for adding magnetic nanoparticles coated by CA and PEG, respectively. Compared with the samples coated by CA, PEG promoted the devitrification of Vs55 in a much more positive way, and the ice growth rates were 0.62 and 6.25 μm/s at the isothermal temperatures of -85 and -75 ℃, respectively. Tliese results indicate that the surface coating of MNPs could significantly affect tlie recrystallization of Vs55, and further work should be conducted in the future research.     

Oriented magnetic material in head and antennae of Solenopsis interrupta ant

Ferromagnetic resonance (FMR) has been used to study the magnetic material in the antennae, head, thorax and abdomen of Solenopsis interrupta ants. The measurements were performed at room temperature (RT). The ferrimagnetic broad lines associated to magnetite/maghemite isolated nanoparticles (high field, HF) and to large nanoparticles or aggregates (low field, LF) in insect spectra are present in the S. interrupta body part spectra, although they slightly differ in resonant fields and lineshapes. The spectral absorption areas show (32±3)%, (24±2)%, (21±2)% and (23±1)% of magnetic material average fractions in antennae, head, abdomen and thorax, respectively. Only the resonance field of the head and antennae showed angular dependence. This work shows that head and antenna of S. interrupta ant present organized magnetic material, indicating a biomineralization process.     

Dynamics of laser-induced cavitation bubble during expansion over sharp-edge geometry submerged in liquid – an inside view by diffuse illumination

Laser ablation in liquids is growing in popularity for various applications including nanoparticle production, breakdown spectroscopy, and surface functionalization. When laser pulse ablates the solid target submerged in liquid, a cavitation bubble develops. In case of “finite” geometries of ablated solids, liquid dynamical phenomena can occur inside the bubble when the bubble overflows the surface edge. To observe this dynamics, we use diffuse illumination of a flashlamp in combination with a high-speed videography by exposure times down to 250 ns. The developed theoretical modelling and its comparison with the experimental observations clearly prove that this approach widens the observable area inside the bubble. We thereby use it to study the dynamics of laser-induced cavitation bubble during its expansion over a sharp-edge (“cliff-like” 90°) geometry submerged in water, ethanol, and polyethylene glycol 300. The samples are 17 mm wide stainless steel plates with thickness in the range of 0.025–2 mm. Bubbles are induced on the samples by 1064-nm laser pulses with pulse durations of 7–60 ns and pulse energies of 10–55 mJ. We observe formation of a fixed-type secondary cavity behind the edge where low-pressure area develops due to bubble-driven flow of the liquid. This occurs when the velocity of liquid overflow exceeds ~20 m s⁻¹. A re-entrant liquid injection with up to ~40 m s⁻¹ velocity may occur inside the bubble when the bubble overflows the edge of the sample. Formation and characteristics of the jet evidently depend on the relation between the breakdown-edge offset and the bubble energy, as well as the properties of the surrounding liquid. Higher viscosity of the liquid prevents the generation of the jet.     

Enhanced oral bioavailability through nanotechnology in Saudi Arabia: A meta-analysis

Oral administration represents the most suitable mean among different means of administering drugs because it ensures high compliance by patients. Nevertheless, the lacking aqueoussolubility, as well as, inadequate metabolic/enzymatic stability of medicines are leading obstacles to successful drug administration by oral route. Among different systems, drug administration systems based on nanotechnology have the potential to surmount the problems associated with oral drug administration. Drug delivery systems based on nanotechnology offer an alternative to deliver antihypertensive agents with enhanced therapeutic effect and bioavailability. In this study, meta-analysis was utilized in combining data relating to oral bioavailability (area under plasma concentration time curve, AUC) enhancement through nanotechnology from multiple studies. Twenty-one studies of the total 37articles included in this study were from the kingdom of Saudi Arabia and were included in a specific meta-analysis. From the analysis conducted, the overall enhancement power of the nanotechnology based formulations on drug bioavailability was found to be 7.94% (95 %CI [5.809, 10.064]). Haven utilized comprehensive and recent data of the confirmed the enhancement of bioavailability using nanotechnology which for this study was grouped into five: solid lipid nanoparticles; polymer based nanoparticles; SNEEDS/Nanoemulsion; liposomes/proliposomes and; nanostructured lipid carriers. Furthermore, the meta-analysis, provided evidence of insignificant differences between APG Bio-SNEDDS and its free drug suspension (Apeginin, APG), though with relative bioavailabiilty of 1.91. Notwithstanding most of the treatment showed a substantial relative bioavailability.     

Size,surface charge and flexibility of vinegar-baked Radix Bupleuri polysaccharide affecting the immune response

Remarkably, nanomaterials can interact with the cells of immune system and either enhance or inhibit its function in many ways. Unfortunately, such valuable information has been overlooked in studies of polysaccharide immune activity. This study isolated a nano-polysaccharide from vinegar-baked Radix Bupleuri by membrane separation system, DEAE-52 and Sephadex-G200. The physicochemical characterization and immunoregulatory activity were studied through DLS, Congo red, Scanning Electron Microscope, UV–Vis, HPGPC, FT-IR, Methylation, NMR, MTT, neutral red and enzyme linked immunosorbent assay. Results showed that VBCP2.5 was an acidic polysaccharide with a molecular weight of 674 kDa. Its monosaccharides composed of mannose, rhamnose, galacturonic acid, glucose, galactose and arabinose at a molar ratio of 1.72: 9.59: 57.63: 5.37: 6.71: 18.99. VBCP2.5 possessed micelle forming ability at 52.574 µg/mL and flexible chain conformation, as well as with a small size distribution ～ 84.99 nm and positive charge in stimulated blood fluid and different from that in deionized water. The microtopography was characterized by irregular lamellar, dendritic, cylindrical or spherical aggregates, with folds and cracks on the surface. Structure analyses showed that VBCP2.5 characterized by high proportion of 1,4 linked-α-D-GalpA and a small fraction of RG-I, some other glycosidic linkages included 1,5 linked-α-L-Araf, 1,3,5 linked-α-L-Araf, 1,3,4 linked-Galp, 1,4,6 linked-Manp, t-α-L-Araf, t-β-D-Glcp and t-α-D-Galp were also comprised. VBCP2.5 exhibited immunomodulatory potential which included the promotion of phagocytosis, the release of NO and the secretion of TNF-α and IL-6 of RAW264.7 cells. The possible activation of macrophages by VBCP2.5 may be mediated through endocytosis pathway. Small size, positive charge, shape and flexible conformation may accelerate this process. The information gathered here could lead to new platform for comprehensive understand included primary structure, properties of nanoscale, and correlation with immunoregulation of polysaccharides.     

Investigation of the effect of nozzle shape on supersonic/hypersonic impactors designed for size discrimination of nanoparticles

In this study the flow field and the nanoparticle collection efficiency of supersonic/hypersonic impactors with different nozzle shapes were studied using a computational modeling approach. The aim of this study was to develop a nozzle design for supersonic/hypersonic impactors with the smallest possible cut-off size d₅₀ and rather sharp collection efficiency curves. The simulation results show that the changes in the angle and width of a converging nozzle do not alter the cut-off size of the impactor; however, using a conical Laval nozzle with an L/D_n ratio less than or equal to 2 reduced d₅₀. The effect of using a cap as a focuser in the nozzle of a supersonic/hypersonic impactor was also investigated. The results show that adding a cap in front of the nozzle had a noticeable effect on decreasing the cut-off size of the impactor. Both flat disks and conical caps were examined, and it was observed that the nozzle with the conical cap had a lower cut-off size.