National Institute Of Materials Physics - Romania

The 1600 nm-extended SWIR photoresponse of SiGe/TiO2 multilayers with Ge-rich SiGe nanocrystals (NCs) is demonstrated. The SiGe NCs based multilayers are obtained by magnetron sputtering deposition of TiO2/ 6x(Ge/SiGe/Ge/TiO2) layers on heated p-Si substrate followed by rapid thermal annealing (RTA). Grazing incidence X-ray diffraction and Raman spectroscopy evidence the formation of cubic Ge-rich SiGe NCs and anatase TiO2. ITO/Ge-rich SiGe NCs based multilayer /p-Si heterostructure diodes, fabricated by depositing top ITO and bottom Al contacts, show n-p behavior. Photocurrent-voltage characteristics measured at 100 K under integral light illumination of reverse biased diode present a photocurrent higher with up to 2 orders of magnitude than the dark current. Spectral photocurrent increases with bias voltage increase and presents a bandgap-related cutoff wavelength of similar to 1600 nm due to the high Ge content of SiGe NCs.

Novel lanthanidomesogens based on lanthanide nitrates carrying three 4-pyridone ligands having two alkoxy chains at the periphery were synthesized and their structure was assigned based on IR spectroscopy and elemental analysis. Their thermal stability was evaluated by TG analysis confirming that the decomposition starts at very high temperatures around 300 degrees C. The liquid crystalline properties were investigated by using a combination of techniques: polarized optical microscopy (POM) and differential scanning calorimetry (DSC) and, for selected compounds, by variable-temperature powder X-ray diffraction. The new liquid crystal display a hexagonal columnar phase (Col(h)) between 63 degrees C and 242 degrees C, depending on the length of the alkyl chain Dielectric spectroscopy on a wide frequency range was used to evaluate the dipolar relaxation processes. The emission properties of a mixture of E7 doped with a selected europium complex filled in a planar cell were investigated on changing the applied voltage, ranging from 0V up to 15V.

Behavior of some wool fabrics as such or functionalized with semiconductor nanoparticles against the photodegradation of Rhodamine B was investigated. The wool samples were commercially purchased, they were chosen to differ by the chemical nature of the yarns, by the size of the 2D texture elements and by the applied pretreatment. The samples were routinely characterized both in the original form and in the form coated with the oxide particles as well to consider the structure, the surface morphology and their changes due to dye deposition. Several techniques were routinely applied: optical microscopy, XRD, SEM, TGA, UV-Vis spectroscopy and FTIR-ATR. Data have shown that TiO2 layer has either an amorphous structure or is highly dispersed. Drops of Rhodamine B solution were deposited by sessile drop method. We have obtained optical images of the wet/colored spot during the radial wicking, collected with a usual camera. Image comparison was made by direct visualisation. The optical images of the spot on fabrics were taken immediately after the dye was applied, after the fabric was dried and afterwards, after the system illumination by UV-vis light as function of the time. The obtained final spots speak about the dye photodegradation in the studied cases.

Pb0.98Bi0.02Zr0.5Fe0.1Nb0.09Ti0.31O3 (PBiZFNT) powder obtained by a solid state reaction technique was uniaxial pressed and sintered at 1200 degrees C in order to fabricate dense thin disk ceramics with different thickness (200 mu up to 600 mu m). The pyroelectric response was influenced by the thickness of the ceramics. The thin ceramic disks of 250 mu m thickness show better pyroelectric signal (approximate to 35 mV) which recommend them for potential use in laser energy meters.

Nanostructured hematite prepared via anodic deposition has been studied as photoanode in neutral and alkaline electrolytes. The morphology of the nanostructures was characterized by SEM, XRD analysis was performed to verify the phase of the films, absorption coefficient and band gap were determined from spectrophotometric measurements and the atomic concentration of Sn in hematite film was estimated from XPS measurements. EIS measurements and photocurrent responses showed the different behavior of hematite photoanode in alkaline and neutral electrolytes. The alkaline medium favors the chemisorption of the water molecules on hematite photoanode, contributing to the diminishing of the charge transfer resistance.

The objective of this study is to investigate the methods to create durable self-cleaning textiles by coating fabrics with TiO2-(1%)Fe-N-graphene (2%). To improve the adherence of the nanoparticles, the polyester/cotton woven fabrics were pre-treated with polyacrylic acid (PA), carboxymethylcellulose (CMC) and polyethylene polyamine resin (EZF). The pre-treated materials were immersed in a doped TiO2 for 30 minutes at 40 degrees C and dried at 125 degrees C. The finished fabrics were stained with methylene blue dye and exposed to visible light. The SEM images show the presence of particles on polymers layers firmly attached on the material surface. The treatments determine the decrease of the exothermic peak (452.48 degrees C), characteristic of the cellulose decomposition, demonstrating an increase of the thermal conductivity of the materials. The doped TiO2-graphene induces a double degradation of methylene blue in comparison with untreated material and the materials treated with CMC, polyacrylic acid and cationic polymer. The effect is maintained after washing.

This work reports the effect of the Mn substitution, rapid solidification technique and heat treatments on the martensitic transformation, magnetic and magnetostrictive properties on the Fe70-xPd30Mnx (x = 1, 3) ferromagnetic shape memory ribbons. The samples were investigated by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, magnetic and magnetostrictive measurements. The thermal treatments induce significant changes in the microstructure and magnetocrystalline anisotropy of the martensitic phase, for Fe67Pd30Mn3 compared to Fe69Pd30Mn1. The competition between the magnetization orientation and twin boundary motion within martensitic variants under magnetic field evidenced in the magnetic-strain curves was discussed and correlated with the magnetic data.

MgB2 has great potential for many applications, thanks to its relatively high critical temperature and low fabrication cost. Large efforts are done to improve the current carrying capabilities of bulks and tapes in view of different application fields, e.g. with the addition of Te and cubic-BN to MgB2. To elucidate the vortex pinning physics exploiting a different dynamic regime, we present here a microwave study of the pinning properties of spark plasma sintered bulk MgB2 with and without the addition of 0.01 % at. Te or cubic-BN. We show the surface resistance R-s of the MgB2 samples measured with a dielectric-loaded resonator at similar to 16.5 GHz and similar to 26.7 GHz in the 10 K-Tc temperature range at fields up to 1.0 T. Then, the MgB2 R., is studied with high frequency vortex motion models in order to obtain the pinning constant (Labusch parameter) and the depinning frequency. Finally, the microwave behavior of MgB2 in the mixed state is compared with the recent results obtained on Nb3Sn.

Neoplastic disease has multifactorial etiology and insidious evolution which make it unlikely to be detected in early stages and very difficult to treat at later times. The effectiveness of standard therapeutic approaches is limited by severe adverse effects, metastasis, and tumor capacity to develop multidrug resistance. The success of inorganic nanomaterial-based therapeutic agents depends on the degree to which these nanostructures satisfy general requirements for drug safety regarding biocompatibility, biodegradability, and stability and on their antitumor efficacy. Fabrication of such nanomedicines requires adequate assessment and engineering of nanomaterial physicochemical characteristics like particle size, specific surface area, surface charge, hydrodynamic size, and magnetic, optical, and photocatalytic properties. Together with surface functionalization and delivery method, these properties dictate the in vivo "biological identity" of the nanomaterial and its fate with respect to cellular uptake and distribution/accumulation inside the body. We reviewed recent literature on interdisciplinary studies regarding applications of inorganic nanomaterials in the treatment of cancer. The major functions that inorganic nanomaterials can play in cancer therapy are: 1. Nanocarriers for therapeutic agents and active targeting ligands for molecules overexpressed on tumor tissues as well as for altered signal transduction pathways. Inorganic nanomaterial-based therapeutic agents are able to reduce tumor growth acting on neoplastic vasculature (by inhibiting angiogenesis, vasculogenesis, and vasculogenic mimicry) or on malignant cells (blocking activation of overexpressed receptors and their specific signaling pathways, inducing oxidative stress, and reducing multidrug resistance). Moreover, inorganic nanomaterials are able to inhibit tumor invasiveness and metastasis by reducing degradation of extracellular matrix, exosome secretion, and cell proliferation at the secondary site. 2. Contrast agents and medical adhesives in cancer surgery: (i). Vital staining of sentinel lymph nodes (SLNs) where the first metastasis appears - the use of carbon nanoparticles, single-walled and multilayer carbon nanotubes, or superparamagnetic iron oxide nanoparticles was associated with a significantly higher number of harvested SLNs in breast and cervical tumors, lung cancer, papillary thyroid carcinoma, and prostate carcinoma. (ii). Nanoparticle-based medical adhesives used for surgical wound closure aqueous suspensions of iron oxide and silicon dioxide nanoparticles were shown to rapidly connect highly vascularized tissues (e.g., liver). 3. Inorganic sensitizers for radiotherapy - gold nanoparticles were reported to significantly enhance the efficiency of ionizing radiation and induce targeted cancer cell apoptosis, tumor growth inhibition, and increases of survival rates in tumor-bearing mice. 4. Antitumor agents based on specific material properties like surface plasmon resonance (photothermal heating), magnetic responsiveness (magnetic hyperthermia), and photocatalysis (photodynamic therapy) - heat generated by plasmonic (gold-based) or magnetic (iron oxide-based) nanomaterials exposed to laser light or alternating magnetic fields, respectively, was shown to efficiently destroy tumors in mouse models or leads to promising results in clinical trials; the antitumor action of photoactivated TiO2-based nanomedicines was assessed in numerous in vitro and several in vivo studies. 5. Adjuvant therapy (iron replacement therapy) - iron oxide colloids (IOC) are more efficient than free iron in treating iron-deficient anemia associated with cancer. Overall, inorganic-organic therapeutic nanoplatforms provide enhanced treatment efficiency, reduced adverse effects, multiple antitumor action mechanisms, facile cell internalization, and diminished multidrug resistance.