Brad R. Weiner

Pressure and temperature dependence of the C2H3O + NO2 reaction

Abstract The temperature (295–374 K) and pressure (2.5–100 Torr) dependences for the rate constant of C 2 H 3 O + NO 2 reaction have been measured by laser flash photolysis/laser-induced fluorescence kinetic spectroscopy. The temperature-dependent reaction for the decay of C 2 H 3 O in the presence of NO 2 is characterized over the measured region by the rate expression k II = (1.48 ± 0.70) × 10 −11 exp(80.7 ± 23.4 K/ T ) cm 3 molecule −1 s −1 . This rate expression is found to be independent of pressure. The results can be explained by a reaction mechanism involving the formation of an energized adduct which subsequently decomposes to products, most likely ketene and nitrous acid.

Collision-induced electronic quenching of aluminum monoxide

Abstract Pulsed laser vaporization—laser-induced fluorescence has been used to produce AlO ( 2 Σ + ). Electronic quenching cross-sections for AlO( 2 Σ + , v ′ = 1) were determined by examining fluorescence decay rates in the presence of eight atomic and diatomic collision partners. The measured electronic quenching cross-sections extend from 0.2 to 14 A 2 . Some possible molecular mechanisms rationalizing the observed quenching cross-sections are discussed.

The laser ablation of gold films at the electrode surface of a quartz crystal microbalance

Abstract We report in this letter the amount of gold removed by ablation with a pulsed laser operating at 532 and 355 nm, by using a quartz crystal microbalance as a mass detector. The results indicate that for the 532 and 355 nm pulsed laser ablation of gold thin films, 1013 - 1015 atoms per pulse are removed over the fluence range of 0.5 - 5.0 J/cm2. The average mass ablated per pulse is found to be a function of the fluence at constant wavelength, and of the wavelength at constant fluence. In addition, the mass sensitivity distribution across the quartz crystal microbalance electrode has been characterized by using the laser ablation technique.

Fabrication and field emission study of novel rod-shaped diamond-like carbon nanostructures

Novel sp(3) rich diamond-like carbon nanorod films were fabricated by a hot filament chemical vapour deposition technique. The results are indicative of a bottom-up synthesis process, which results in a hierarchical structure that consists of microscale papillae comprising numerous nanorods. The papillae have diameters ranging from 2 to 4 microm and the nanorods have diameters in the 35-45 nm range. A growth mechanism based on the vapour-liquid-solid mechanism is proposed that accounts for the morphological aspects at the microscale and nanoscale. Investigation of field emission properties of fabricated nanorods reveals a low turn-on field of about 4.9 V microm( - 1) at 1 nA and a high field-enhancement factor.

Genesis of diamond nanotubes from carbon nanotubes

We synthesized sp3-rich crystalline tubular structures, referred to as diamond nanotubes (DNTs), by hot-filament chemical vapor deposition and characterized them using SEM, TEM, EELS, and Raman spectroscopy. The images and spectra indicate the formation of DNTs with internal diameter of about 7–10u2009nm and external diameter of about 20–30u2009nm. During the fabrication process, CNTs form first and give way to the synthesis of DNTs. The DNTs show good field emission properties and enhanced temporal stability as compared to CNTs.

Isotope effects and wavelength dependence in the rotational state distributions of the diatomic photofragments SH and SD from the photodissociation of H2S and D2S

Abstract We employ a semi-empirical model that utilizes a kinematic distribution function to calculate the rotational state population distributions of diatomic photofragments from the photodissociation of isotopically variant triatomic molecules. The numerically evaluated rotational distributions of the photofragments, SH and SD, are compared with experimental data on the nascent rotational state population distributions of the diatomic photofragments resulting from the laser photolysis of H 2 S (λ photolysis =193, 222 and 248 nm) and D 2 S (λ photolysis =193 and 222 nm).

Hot Filament Chemical Vapor Deposition: Enabling the Scalable Synthesis of Bilayer Graphene and Other Carbon Materials

The hot filament chemical vapor deposition (HFCVD) technique is limited only by the size of the reactor and lends itself to be incorporated into continuous roll-to-roll industrial fabrication processes. We discuss the HFCVD reactor design and the interplay between the reactor parameters, such as filament and substrate temperatures, filamentto-substrate distance, and total pressure. Special attention is given to the large-area synthesis of bilayer graphene on copper, which is successfully grown by HFCVD with transmittance greater than 90% in the visible region and no gaps. We also discuss the HFCVD synthesis of carbon nanotubes, microcrystalline diamond, and nanocrystal‐ line diamond.

In situ phase-modulated ellipsometry study of the surface damaging process of silicon under atomic hydrogen

We employed in situ phase-modulated ellipsometry in the monitoring of surface damage to monocrystalline silicon (Si) under plasma conditions typical for the chemical vapor deposition of diamond. Single-wavelength kinetic and spectroscopic ellipsometry measurements were done and complemented with Raman spectroscopy, in order to characterize the surface conditions. It was found that heating the Si substrate to 700°C in the presence of molecular hydrogen produces etching of the native oxide layer. When the hot bare silicon surface is submitted to atomic hydrogen, it becomes rough in minutes. Modeling of the spectroscopic ellipsometry provided a quantitative physical picture of the surface damage, in terms of the roughness layer thickness and void fraction. The results indicate that by the time a thin film starts to grow on these silicon surfaces, like in the chemical vapor deposition of diamond, the roughness produced by the atomic hydrogen has already determined to a large extent the rough nature of the film to be grown.

Abstract 2196: Improving cytotoxicity against cancer cells by chemo-photodynamics combined modalities using silver/graphene quantum dots/doxorubicin nanoconjugates

Tumor microenvironment complexity render chemotherapy and radiotherapy ineffective to eradicate highly aggressive tumors. For this reason, we are interested to find new avenues that can improve clinical outcomes. Recently, different nanomaterials such as Graphene Quantum Dots (GQDs) have been explored in treatments for a broad range of diseases, including cancer therapeutics. GQDs are nanometer-sized fragments (2-20 nm) of graphene, which have shown unique electrical, optical and mechanical properties. We hypothesize that the unique physical and chemical properties of the Graphene Quantum Dots (GQDs) along with the anticancer properties of silver (Ag) can provide an alternative to the challenges presently encountered in traditional cancer therapy regimens. In this study functionalized silver decorated graphene quantum dots (Ag-GQDs) nanocomposites were synthesized by a bottom-up approach by the pulsed laser irradiation of a liquid hydrocarbon precursor containing silver ions. The Ag-GQDs were characterized by UV-Vis spectroscopy, transmission electron microscopy, and Fourier transform IR spectroscopy. The Ag-GQD nanocomposites were tested in the treatment of cervical cancer HeLa cells and prostate cancer cells DU-145. The Ag-GQD nanocomposites demonstrated high potential in the delivery of Doxorubicin to cancer cells and an anticancer activity boost due to their intrinsic properties. Interestingly, we observed an increase in the activity of caspase-3/7 in DU145 and HeLa when treated with such nanoparticles. The photo-activation of Ag-GQDs with 425 nm radiation increased the levels of Reactive Oxygen Species (ROS) in both cell lines, inducing cell death by DNA damage. The combination of the chemo-photodynamic therapies using Ag-GQDs conjugated with DOX remarkably enhanced the treatment efficacy of HeLa and DU145, as compared to treatment by using each modality alone. HeLa. Fluorescence imaging results showed that Ag-GQDs deliver DOX to the nucleus of cancer cells, which suggests they may deliver other cargos. Also, to confirm whether the decrease in the cells viability upon treatment with Ag-GQDs was caused by toxicity, we tested a non-transformed cell line. The data suggest that the effect is due to the intrinsic effect of Ag-GQDs and not by toxicity. The Ag-GQDs thus offer a general platform for incorporating multiple therapeutic modalities for treating different types of cancer and they represent a significant breakthrough in nanomedicine for potential translation to the clinic. Further studies are necessary to elucidate the exact mechanism(s) of Ag-GQDs in releasing their cargo, and to test them in vivo. In summary, we developed a novel, multi-functional, and biocompatible PEGylated Ag-GQDs nanocomposites that combines two therapeutic modalities, chemotherapy and photodynamic therapy, into one platform for treatment of different type of cancers. Citation Format: Joel Encarnacion-Rosado, Khaled Habiba, Kenny Garcia-Pabon, Brad R. Weiner, Gerardo Morell. Improving cytotoxicity against cancer cells by chemo-photodynamics combined modalities using silver/graphene quantum dots/doxorubicin nanoconjugates. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2196.