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Co0.5Cd0.5-xCuxFe1.95Ce0.05O4 (0 ≤ x ≤ 0.5) nanoferrites were successfully synthesized via sol-gel-assisted autocombustion method. The effects of Cu substation in the spinel matrix on structural, optical, and dielectric properties have been studied. XRD data confirms the successful synthesis of single phase cubic spinel structure. FTIR spectroscopy and Raman spectroscopy further confirm the formation of single phase spinel structure. Ultraviolet-visible (UV-vis) spectroscopy is used to measure the energy bandgap of the prepared samples. The energy bandgap is found in the range 1.02 to 1.96 eV and decreases when Cu concentration increases. Dielectric parameters like dielectric constant, tangent loss, and ac impedance are determined as a function of frequency of applied field and are described with the help of Koop’s theory. It is observed that all these parameters decrease with increase in frequency and become independent of frequency above 1 MHz. The dielectric properties of Cu-substituted Co-Cd spinel ferrites make these ferrites potential candidate for applications in high frequency range.

In this paper, we have tailored the structural, magnetic and dielectric properties of Ni0.5Zn0.3Cd0.2Fe2-yLayO4 (y = 0.0–0.21) nano-structured spinel ferrites by the substitution of La3+ ions. The investigated samples were synthesized by Sol-gel auto-combustion method and were characterized using XRD, SEM, VSM, FTIR and dielectric measurements. Single phase nanostructure formation of synthesized material was confirmed by XRD analysis. The effect of La3+ ions on crystallite size, grain size, lattice constant and bulk densities was calculated and it was found that lattice constant first increased upto concentration y = 0.105 then decreased with further substitution of dopant ions. FTIR results for all synthesized samples demonstrated two absorption bands at υ1 = 540.8 cm−1 and υ2 = 490.8 cm−1 corresponds to tetrahedral and octahedral sites of spinel structure respectively. With the increase in La3+ ions concentration, saturation magnetization and remanence both found to be decreased down to lowest Ms value of 34.1 emu/g which is not yet reported in the literature according to best of our knowledge. Dielectric results showed that by decreasing frequency, both dielectric loss and dielectric constant decreases. AC conductivity has two regions, at low frequency region ac conductivity increases while at high frequency region, it decreases with increasing frequency. The measured results for all synthesized nano-ferrites suggested that synthesized nanoferrites are recommended for high frequency and microwave absorbing applications.

Nano-thin films of Lu2O3 with 80nm thickness have been deposited on metal-coated glass substrate in metal-insulator-metal (MIM) geometry by electron-beam evaporation technique. High field and temperature dependent electrical characterization on grown MIM structures have been investigated in symmetric electrode configuration using Al, Cr or Cu metals. The temperature dependent I-T characteristic features have been found to support the conduction mechanism across MIM systems to be an electrode-limited process except for Al-Lu2O3-Al device, which show Poole-Frenkel mechanism in high electric field region. The associated parameters such as activation energy (ΔE), coefficient of barrier lowering (β) and effective height of Schottky barrier at zero biasing (Φo) have been evaluated at different values of temperature and electric field to further investigate the dominent conduction mechanism.

High temperature colloidal doping method has been used to synthesistransition metals (M = Cr, Mn, Co, Ni, Cu) MCdS/ ZnS core/shell nanoparticles. Transition metalsions were incorporated into the CdS quantum dots pursued by 6 mono lyres of the ZnS materials, which was enveloped doped CdS um dots. These doped nanoparticles were further studied using transmission electron microscopy (TEM), time resolved spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy and photoluminescence (PL) spectroscopy measurements. Transition metalsdoped CdS/ZnS nanoparticles confirm the dual-peaks, first peak (sharp emission peak) is due to CdS quantum dot at 435 nm ; second peak (broad emission peak )(510–660 nm) is come from Transition metalions as compared to CdS/ZnS Quantum dots.

Cerium oxide (CeO2) nanoparticles (also called nanoceria) have broad range of applications in various fields, especially in the biomedical sector. Doping of CeO2with different elements can vary the optical, structural, biomedical and electrical characteristics of cerium dioxide nanoparticles. In this study CeO2was doped with different concentrations of Manganese (Mn) and Iron (Fe). The characterization techniques used for analysis of CeO2nanoparticles were X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and I–V analysis. The particles were also tested for Antibacterial and Antifungal activity. For antibacterial activity test, gram-positive test was conducted by Staphylococcus aureus and gram-negative tested on E. coli. The antifungal activity was tested with Candida Albicans.

A series of Cd0·5Cu0.5-xMgxFe1.95La0·05O4 (x = 0.0, 0.125, 0.25, 0.375, 0.5) nano ferrites was synthesized via sol-gel auto combustion route. XRD analysis confirmed the development of spinel ferrites. Different structural parameters like lattice constant, tetrahedral and octahedral radii, oxygen ion parameter, tolerance factor, bond lengths, edge lengths and interionic distances were calculated from XRD data. It was observed that by increasing the Mg2+ concentration, lattice constant and crystallite size were increased. Energy band gap was measured using UV–vis spectroscopy and found in the range 1.79–2.36 eV. Dielectric properties of the prepared samples were also studied and it was found that dielectric constant and ac conductivity were decreased with increase in Mg2+ content. The study indicates that Cd0·5Cu0.5-xMgxFe1.95La0·05O4 nano ferrites have great potential to be utilized in high frequency devices as microwave absorbing material and in optoelectronic devices.

Herein, we developed and characterized pH responsive semi interpenetrating network (semi-IPN) of Pectin-g-poly(AA)/PVP by free radical polymerization. These hydrogels were developed to overcome hurdles associated with; i) mechanical strength of formed system which was dealt by the use of combination of natural (pectin) and synthetic (PVP) polymers and ii) oral administration of drugs requiring action in distal part of gastrointestinal tract which was addressed by employing pectin and acrylic acid which conferred pH sensitivity due to carboxylic group in their structure. Structurally and morphologically, developed semi-IPN hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and X-ray diffraction (XRD). Chemically, they were evaluated for swelling and release kinetics. Semi-IPN hydrogels restricted the swelling of system and therefore the release of dexamethasone sodium phosphate (DSP) at pH 1.2 but released it in controlled manner at pH 7.4 by non-Fickian diffusion. . Biologically, acute toxicity testing of developed semi-IPN hydrogels, revealed biocompatibility and safety of hydrogels after oral administration. Conclusively, prepared semi-IPN hydrogels showed good mechanical properties, swelling, biocompatibility, pH dependent DSP release for possible treatment of inflammatory bowel diseases.

A two-step high temperature colloidal doping technique has been used to synthesis Co-Ni co-doped CdS/ZnS core/shell nanocrystals in organic phase. Co-Ni ions were incorporated into the CdS quantum dots core pursued by ZnS shell (six monolayers) which was developed on top of it. The co-doped nanocrystals were further characterized usingtransmission electron microscopy (TEM),X-ray diffraction (XRD), ultraviolet-visible (UV-VIS) spectroscopy and photoluminescence (PL) spectroscopy measurements. The co-doped CdS/ZnS nanocrystals show two peaks; the sharp emission peak is due to CdS quantum dot at 440 nm while the broad emission peak (520–650nm) is due typical to Co-Ni ions as compared to undoped CdS/ZnS nanocrystals.

The aim of the study was to control the size of gelatin nanoparticles under varied conditions of nanoprecipitation. The gelatin concentration in the solvent phase and different combination of nonsolvents was used to see influence on the size, polydispersity and recovery yield of produced nanoparticles. The size of the nanoparticles was determined by dynamic light scattering. The yield of gelatin nanoparticles after freezedrying was found gravimetrically. The morphology of nanoparticles was studied by scanning electron microscopy. The results suggest that the size of nanoparticles can be tuned within a range 250–350 nm with low polydispersity index because of the inhibition of particle aggregation during crosslinking. The produced nanoparticles are of spherical shape with a smooth surface. We found that the recovery yield was also dependent on the gelatin concentration in the solvent phase.

Manganese-doped CdS/ZnS quantum dots have been used as energy donors in a Förster-like resonance energy transfer (FRET) process to enhance the effective lifetime of organic fluorophores. It was possible to tune the effective lifetime of the fluorophores by about six orders of magnitude from the nanosecond (ns) up to the millisecond (ms) region. Undoped and Mn-doped CdS/ZnS quantum dots functionalized with different dye molecules were selected as a model system for investigating the multiple energy transfer process and the specific interaction between Mn ions and the attached dye molecules. While the lifetime of the free dye molecules was about 5 ns, their linking to undoped CdS/ZnS quantum dots led to a long effective lifetime of about 150 ns, following a non-exponential transient. Manganese-doped core-shell quantum dots further enhanced the long-lasting decay time of the dye to several ms. This opens up a pathway to analyse different fluorophores in the time domain with equal spectral emissions. Such lifetime multiplexing would be an interesting alternative to the commonly used spectral multiplexing in fluorescence detection schemes. Fil: Kaiser, Uwe. Philipps-University Marburg, ; Alemania Fil: Sabir, Nadeem. Philipps-University Marburg, ; Alemania Fil: Carrillo-Carrion, Carolina. Philipps-University Marburg, ; Alemania Fil: Del Pino, Pablo. CIC biomaGUNE; España Fil: Bossi, Mariano Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina Fil: Heimbrodt, Wolfram. Philipps-University Marburg, ; Alemania Fil: Parak, Wolfgang J.. Philipps-University Marburg, ; Alemania. CIC biomaGUNE; España

Quantum-dot-based photoelectrochemical sensors are powerful alternatives for the detection of chemicals and biochemical molecules compared to other sensor types, which is the primary reason as to why they have become a hot topic in nanotechnology-related analytical methods. These sensors basically consist of QDs immobilized by a linking molecule (linker) to an electrode, so that upon their illumination, a photocurrent is generated which depends on the type and concentration of the respective analyte in the immediate environment of the electrode. The present review provides an overview of recent developments in the fabrication methods and sensing concepts concerning direct and indirect interactions of the analyte with quantum dot modified electrodes. Furthermore, it describes in detail the broad range of different sensing applications of such quantum-dot-based photoelectrochemical sensors for inorganic and organic (small and macro-) molecules that have arisen in recent years. Finally, a number of aspects concerning current challenges on the way to achieving real-life applications of QD-based photochemical sensing are addressed.