Non‐Newtonian Polymer–Nanoparticle Hydrogels Enhance Cell Viability during Injection

Drug delivery and cell transplantation require minimally invasive deployment strategies such as injection through clinically relevant high‐gauge needles. Supramolecular hydrogels comprising dodecyl‐modified hydroxypropylmethylcellulose and poly(ethylene glycol)‐block‐poly(lactic acid) have been previously demonstrated for the delivery of drugs and proteins. Here, it is demonstrated that the rheological properties of these hydrogels allow for facile injectability, an increase of cell viability after injection when compared to cell viabilities of cells injected in phosphate‐buffered saline, and homogeneous cell suspensions that do not settle. These hydrogels are injected at 1 mL min^?1 with pressures less than 400 kPa, despite the solid‐like properties of the gel when at rest. The cell viabilities immediately after injection are greater than 86% for adult human dermal fibroblasts, human umbilical vein cells, smooth muscle cells, and human mesenchymal stem cells. Cells are shown to remain suspended and proliferate in the hydrogel at the same rate as observed in cell media. The work expands on the versatility of these hydrogels and lays a foundation for the codelivery of drugs, proteins, and cells.     

Characterization of Fe3O4 Nanoparticles for Applications in Catalytic Activity in the Adsorption/Degradation of Methylene Blue and Esterification

The aim of this study is to evaluate the applicability of the catalytic activity (CA) of the Fe₃O₄ magnetic system in the adsorption/degradation of methylene blue and esterification. The thermal decomposition method allowed the preparation of Fe₃O₄ nanoparticles. The crystallites of the Fe₃O₄ structural phase present an acicular form confirmed by X-ray diffraction. Transmission electron microscopy results identified the acicular shape and agglomeration of the nanoparticles. Mössbauer spectroscopy showed that the spectrum is composed of five components at room temperature, a hyperfine magnetic field distribution (HMFD), two sextets, a doublet, and a singlet. The presence of the HMFD means that a particle size distribution is present. Fluorescence spectroscopy studied the CA of the nanoparticles with methylene blue and found adsorption/degradation properties of the dye. The catalytic activity of the nanoparticles was evaluated in the esterification reaction by comparing the results in the presence and absence of catalyst for the reaction with isobutanol and octanol, where it is observed that the selectivity for the products MIBP and MNOP is favored in the first three hours of reaction.     

The infrared spectra of SiH3F: ν3 and ν4 bands

Infrared spectra of silyl fluoride were recorded at a resolution of 0.06 cm^?1 using a Nicolet Fourier transform interferometer. Analyses of the ν₃ and ν₄ bands are presented for ²⁸SiH₃F, together with work on ²⁹SiH₃F, ³⁰SiH₃F, and various hot bands.     

Organometalloidal derivatives of the transition metals: IX. Synthesis and the crystal structure of (η5-C5H5)Fe(CO)2SiMe2-SiPh3

Reaction of (η⁵-C₅H₅)(CO)₂FeNa with ClSiMe₂-SiPh₃ yields (η⁵-C₅H₅)-Fe(CO)₂SiMe₂-SiPh₃. The crystal structure of the compound has been determined by X-ray diffraction. The SiSi bond distance is 2.374(1) Å, which is longer by 0.018 Å than that in Me₃Si-SiPh₃. This difference is in agreement with spectroscopic data, and is presumably due to the σ-donor property of the silyl group. The SiFe bond length is 2.346(1) Å.     

Determination of thiolcarbamate herbicides in natural water by HPLC with spectrophotometric detection

Summary Thiolcarbamates used for killing weed seeds were determined in natural waters by HPLC with spectrophotometric detector. Methanol-water (80:20) containing 0.01 mol/l ammonium acetate buffer pH 5.0 was used as mobile phase. The column was thermostated at 35°C. Seppak C18 cartridges were used for sample preparation and preconcentration. The minimum detectable concentration for samples of 100 ml was 0.5 ng/ml.     

Generalized differentiability conditions for Newton's method

The use of majorizing sequences is the usual way to prove theconvergence of Newton's method. An alternative technique tomajorizing sequences is provided in this paper, in which threescalar sequences are used, so that the analysis of convergenceis simplified when the traditional convergence condition isrelaxed. An application to a nonlinear integral equation isalso given, which is also solved and the solution approximatedby a discretization process.     

Spectroscopic characterization of metal chloride/polyamide complexes

Complexes formed between metal halides MX_n (M=Li, Zn, Fe; X=Cl, Br) and an amorphous polyamide have been characterized by Infrared and Raman spectroscopies. They provide examples of the large variety of situations which can be generated by varying the concentration of the salts and their Lewis acidity. The LiX salts are dissociated and the lithium ion interacts with four amide oxygens or less, depending on the concentration, while the anion establishes N-H...X⁻ hydrogen bonds. Complexes with LiTFSI exhibit some ionic conductivity. Zinc halides are complexed under the form of a bent ZnX₂ molecule strongly coordinated to two or one amide oxygens depending on the concentration. Finally, FeCl₃ is ionized in the whole investigated concentration range into FeCl ₄ ⁻ and FeCl₂(L) ₄ ⁺ where L is the amide ligand coordinated to iron by its oxygen. Paper presented at the 2nd Euroconference on Solid State Ionics in Funchal, Madeira, Portugal, Sept. 10–16, 1995