Biomass Catalytic Upconversion with a Metallic Catalyst Bed under Radio Frequency Induction Heating

This study investigated the thermal performances of platinum particles when coupled on a steel support, under the application of a radio frequency (RF) field. Platinum nanoparticles were reduced on the surfaces of type-316 stainless steel balls, based on published methods of Pt reduction from chloroplatinic acid. Alternatively, 1wt. % Pt/Al2O3 commercial catalyst pellets were mixed with stainless steel balls and investigated for hydro-deoxygenation of pyrolysis oil from pine sawdust biomass. The catalysts were placed inside an electric insulator tube suspended within a looping copper coil connected to the induction heater, and heated at different power levels. An infrared camera was utilized to record the surface temperature profile during heating of Pt-coated balls and non-coated balls. Pt particles deposited onto silica beads showed no surface heating when placed inside an RF field. The Pt-coated steel systems, however, showed rapid heating of the surfaces following a first order response. The catalysts were characterized via SEM/EDX, XPS and XRD. Preliminary upgrading tests using these Pt-steel balls did not indicate any effect. The lack of catalytic activity was attributed to the limited surface area per unit volume of the Pt coating due to the large sizes and non-porous structure of the steel balls. For the catalytic upgrading experiment with the use of the Pt/Al2O3 commercial catalyst pellets mixed with steel balls, heating of the catalyst bed with the induction heater was compared with a conventional method of heating using electric tape around the catalyst bed reactor. Partial deoxygenation was successfully achieved in the catalytic upgrading of pyrolysis oil using Pt/Al2O3 pellets mixed with steel balls at 234°C, with the use of the induction heater. The molar O/C ratio of the oil decreased from 1.36 to 0.51. No deoxygenation was observed using the conventional heating method with the electric tape under identical conditions as both carbon and oxygen appeared to be removed at approximately equal rates, with the carbon being deposited in the form of coke onto the catalyst instead of being recovered in the liquid

Metastatic unilateral retinoblastoma to the contralateral orbital optic nerve presenting with optic disc edema

Retinoblastoma (Rb) is a malignant eye tumor that poses a significant risk of mortality once metastasized. We present the case of a 30-month-old girl with left-sided Rb who underwent primary enucleation with pathology-confirmed diagnosis without high-risk pathologic features. Therefore she did not receive adjuvant chemotherapy. Six months later, the patient developed skull bone and bone marrow metastasis, which were treated with systemic chemotherapy, excision of bone metastasis, focal radiation treatment to the site of osseous metastasis, and bone marrow transplantation. Follow-up for two years was unremarkable until she presented with vision loss in the remaining contralateral eye. Ophthalmic examination revealed severe optic disc edema without intraocular masses, initially thought to be optic neuritis. However, the patient did not respond to steroids, and the initial cerebrospinal fluid (CSF) analysis was negative. This was repeated based on high clinical suspicion of metastasis, revealing only a few malignant cells. The presentation and appearance of the optic nerve were considered metastasis-related and treated with radiation therapy, which resulted in dramatic clinical and radiological improvement. Unfortunately, a few weeks later, the patient developed lower limb weakness, and imaging showed diffuse leptomeningeal metastasis, confirmed by CSF findings. This case represents the first documented isolated contralateral optic nerve metastasis in Rb

Primary Immunodeficiency Diseases in Children: 15 Year Experience in a Tertiary Care Medical Center in Qatar

Background Primary immunodeficiency diseases (PID) are a group of heterogeneous, rare, genetic, mainly childhood disorders that affect specific components of immune system leading to serious complications

Monitoring the Photocleaving Dynamics of Colloidal MicroRNA-Functionalized Gold Nanoparticles Using Second Harmonic Generation

© 2015 American Chemical Society. Photoactivated drug delivery systems using gold nanoparticles provide the promise of spatiotemporal control of delivery that is crucial for applications ranging from regenerative medicine to cancer therapy. In this study, we use second harmonic generation (SHG) spectroscopy to monitor the light-activated controlled release of oligonucleotides from the surface of colloidal gold nanoparticles. MicroRNA is functionalized to spherical gold nanoparticles using a nitrobenzyl linker that undergoes photocleaving upon ultraviolet irradiation. The SHG signal generated from the colloidal nanoparticle sample is shown to be a sensitive probe for monitoring the photocleaving dynamics in real time. The photocleaving irradiation wavelength is scanned to show maximum efficiency on resonance at 365 nm, and the kinetics are investigated at varying irradiation powers to demonstrate that the nitrobenzyl photocleaving is a one-photon process. Additional characterization methods including electrophoretic mobility measurements, extinction spectroscopy, and fluorimetry are used to verify the SHG results, leading to a better understanding of the photocleaving dynamics for this model oligonucleotide therapeutic delivery system

Monitoring the Photocleaving Dynamics of Colloidal MicroRNA-Functionalized Gold Nanoparticles Using Second Harmonic Generation

Photoactivated drug delivery systems using gold nanoparticles provide the promise of spatiotemporal control of delivery that is crucial for applications ranging from regenerative medicine to cancer therapy. In this study, we use second harmonic generation (SHG) spectroscopy to monitor the light-activated controlled release of oligonucleotides from the surface of colloidal gold nanoparticles. MicroRNA is functionalized to spherical gold nanoparticles using a nitrobenzyl linker that undergoes photocleaving upon ultraviolet irradiation. The SHG signal generated from the colloidal nanoparticle sample is shown to be a sensitive probe for monitoring the photocleaving dynamics in real time. The photocleaving irradiation wavelength is scanned to show maximum efficiency on resonance at 365 nm, and the kinetics are investigated at varying irradiation powers to demonstrate that the nitrobenzyl photocleaving is a one-photon process. Additional characterization methods including electrophoretic mobility measurements, extinction spectroscopy, and fluorimetry are used to verify the SHG results, leading to a better understanding of the photocleaving dynamics for this model oligonucleotide therapeutic delivery system

Comparison of thermally actuated retro-diels-alder release groups for nanoparticle based nucleic acid delivery

The present study explores alternate pericyclic chemistries for tethering amine-terminal biomolecules onto silver nanoparticles. Employing the versatile tool of the retro-Diels-Alder (rDA) reaction, three thermally-labile cycloadducts are constructed that cleave at variable temperature ranges. While the reaction between furan and maleimide has widely been reported, the current study also evaluates the reverse reaction kinetics between thiophene-maleimide, and pyrrole-maleimide cycloadducts. Density Functional Theorem (DFT) calculations used to model and plan the experiments, predict energy barriers for the thiophene-maleimide reverse reaction to be greatest, and the pyrrole-maleimide barriers the lowest. Based on the computational analyses, it is projected that the cycloreversion rate would occur slowest with the thiophene, followed by furan, and finally pyrrole would yield the promptest release. These thermally-responsive linkers, characterized by Electrospray Ionization Mass Spectrometry, H and C NMR, are thiol-linked to silver nanoparticles and conjugate single stranded siRNA mimics with 5\u27 fluorescein tag. Second harmonic generation spectroscopy (SHG) and fluorescence spectroscopy are used to measure release and rate of release. The SHG decay constants and fluorescence release profiles obtained for the three rDA reactions confirm the trends obtained from the DFT computations

Near-Infrared Photothermal Release of siRNA from the Surface of Colloidal Gold-Silver-Gold Core-Shell-Shell Nanoparticles Studied with Second-Harmonic Generation

© 2018 American Chemical Society. Photothermal release of oligonucleotides from the surface of plasmonic nanoparticles represents a promising platform for spatiotemporal controlled drug delivery. Here we demonstrate the use of novel gold-silver-gold core-shell-shell (CSS) nanoparticles to study the photothermal cleaving and release of micro-RNA (miRNA) mimics or small interfering RNA (siRNA) under near-infrared (NIR) irradiation. The furan-maleimide-based Diels-Alder adduct cleaves thermally above 60 °C and is used to bind siRNA to the colloidal nanoparticle surface in water. We investigate the photothermal cleaving kinetics of siRNA under different NIR laser powers using surface-sensitive time-dependent second-harmonic generation (SHG) spectroscopy. The photothermal release of siRNA from the surface of CSS nanoparticles is significantly higher than that from the surface of gold nanoparticles (GNPs) under similar experimental conditions. These results demonstrate that plasmonic CSS nanoparticles with photothermal cleaving linkers have important potential applications for nanoparticle-based NIR-mediated drug-delivery systems