Search

Atmospheric pressure plasma jets (APPJs) are used to improve the adhesive and hydrophilic properties of commodity hydrocarbon polymers such as polypropylene, polyethylene, and polystyrene (PS). These improvements largely result from adding oxygen functional groups to the surface. PS functionalization is of interest to produce high value biocompatible well-plates and dishes, which require precise control over surface properties. In this paper, we discuss results from a computational investigation of APPJ functionalization of PS surfaces using He/O2/H2O gas mixtures. A newly developed surface reaction mechanism for functionalization of PS upon exposure to these plasmas is discussed. A global plasma model operated in plug-flow mode was used to predict plasma-produced species fluxes onto the PS surface. A surface site balance model was used to predict oxygen-functionalization of the PS following exposure to the plasma and ambient air. We found that O-occupancy on the surface strongly correlates with the O-atom flux to the PS, with alcohol groups and cross-linked products making the largest contributors to total oxygen fraction. Free radical sites, such as alkoxy and peroxy, are quickly consumed in the post-plasma exposure to air through passivation and cross-linking. O-atom fluences approaching 1017 cm−2 saturate the O-occupancy on the PS surface, creating functionality that is not particularly sensitive to moderate changes in operating conditions.

Even if ion pumps are widely and mostly used in ultra-high vacuum (UHV) conditions, virtually every existing ion pump has its maximum pumping speed around 1E-6 mbar (1E-4 Pa). Discharge intensity in the ion pump Penning cell is defined as the current divided by pressure . (I/P)This quantity reflects the rate of cathode bombardment by ions, which underlies all of the various pumping mechanisms that occur in ion pumps (chemisorption on sputtered material, ion burial, etc.), and therefore is an indication of pumping speed. A study has been performed to evaluate the influence of magnetic fields and cell dimensions on the ion pump discharge intensity and consequently on the pumping speed at different pressures. As a result, a combination of parameters has been developed in order to design and build an ion pump with the pumping speed peak shifted towards lower pressures. Experimental results with several different test set-ups are presented and a prototype of a new 200 l/s ion pump with the maximum pumping speed in the 1E-8 mbar (1E-6 Pa) is described. A model of the system has also been developed to provide a framework for understanding the experimental observations.

We present a solid-state NMR study of H2 molecules confined inside the cavity of C70 fullerene cages over a wide range of temperatures (300 K to 4 K). The proton NMR spectra are consistent with a model in which the dipole-dipole coupling between the ortho-H2 protons is averaged over the rotational/translational states of the confined quantum rotor, with an additional chemical shift anisotropy δ(H)(CSA)=10.1 ppm induced by the carbon cage. The magnitude of the chemical shift anisotropy is consistent with DFT estimates of the chemical shielding tensor field within the cage. The experimental NMR data indicate that the ground state of endohedral ortho-H2 in C70 is doubly degenerate and polarized transverse to the principal axis of the cage. The NMR spectra indicate significant magnetic alignment of the C70 long axes along the magnetic field, at temperatures below ~10 K.

Inelastic neutron scattering, far-infrared spectroscopy, and cryogenic nuclear magnetic resonance are used to investigate the quantized rotation and ortho–para conversion of single water molecules trapped inside closed fullerene cages. The existence of metastable ortho -water molecules is demonstrated, and the interconversion of ortho -and para -water spin isomers is tracked in real time. Our investigation reveals that the ground state of encapsulated ortho water has a lifted degeneracy, associated with symmetry-breaking of the water environment.

Helicon waves are excited in a plasma wave facility by a half-turn double-helix antenna operating at 13.56 MHz for static magnetic fields ranging from 200 to 1000 G. A non-perturbing optical probe located outside the Pyrex™ plasma chamber is used to observe 443 nm Ar II emission that is spatially and temporally correlated with the helicon wave. The Ar II emission is measured along with wave magnetic and Langmuir probe density measurements at various axial and radial positions. 105 GHz interferometry is used to verify the bulk temperature corrected Langmuir probe measurements. The measured peak Ar II emission phase velocity is compared to the measured wave magnetic field phase velocity and code predicted wave phase velocity for the transition and blue mode regimes. Very different properties of the optical emission peak phase and wave characteristics for the transition and helicon modes of operation are observed. Comparison of the experimental results with the ANTENAII code [Y. Mouzouris and J. E. Scharer, ...

We report an inelastic neutron scattering (INS) study of H2 molecule encapsulated inside the fullerene C60 which confirms the recently predicted selection rule, the first to be established for the INS spectroscopy of aperiodic, discrete molecular compounds. Several transitions from the ground state of para-H2 to certain excited translation-rotation states, forbidden according to the selection rule, are systematically absent from the INS spectra, thus validating the selection rule with a high degree of confidence. Its confirmation sets a precedent, as it runs counter to the widely held view that the INS spectroscopy of molecular compounds is not subject to any selection rules.

Inelastic neutron scattering (INS) has been employed to investigate the quantum dynamics of water molecules permanently entrapped inside the cages of C60 fullerene molecules. This study of the supramolecular complex, H2O@C60, provides the unique opportunity to study isolated water molecules in a highly symmetric environment. Free from strong interactions, the water molecule has a high degree of rotational freedom enabling its nuclear spin isomers, ortho-H2O and para-H2O to be separately identified and studied. The INS technique mediates transitions between the ortho and para spin isomers and using three INS spectrometers, the rotational levels of H2O have been investigated, correlating well with the known levels in gaseous water. The slow process of nuclear spin conversion between ortho-H2O and para-H2O is revealed in the time dependence of the INS peak intensities over periods of many hours. Of particular interest to this study is the observed splitting of the ground state of ortho-H2O, raising the three-fold degeneracy into two states with degeneracy 2 and 1 respectively. This is attributed to a symmetry-breaking interaction of the water environment.

The water-endofullerene H2O@C60 provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H2O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H2O molecules is catalysed by (13)C nuclei present in the cages.

Low-pressure microwave-excited microplasmas have a wide variety of potential applications, including their use as UV photoionization sources for mass spectrometry. Resonant microwave microstrip architectures can be used to initiate and sustain these microplasmas. When operated in a windowless configuration, the plasma plume exiting from an aperture in the plasma confinement structure contains a complex mixture of particle species (UV photons, groundstate neutrals, metastables, and plasma electrons and ions)1. Understanding the makeup of this plume is critical to optimize parameters for photoionization, or any other application where exposure to the plasma plume takes place.

Capacitively coupled microplasmas in dielectric cavities have a range of applications from VUV lighting sources for surface treatment to radical production. Due to the large surface-to-volume ratio of these devices, the wall mediated dynamics of plasma transport are important to the uniformity and confinement of the plasma. For example, there may be applications where a plume of ionized gas is desired from the microcavity - whereas other applications may require a confined plasma emitting only VUV photons

Optical emission spectroscopy is employed to determine the Fe I excitation temperature (Texc) and NH rotational temperature (Trot) inside the microwave excitation region of an atmospheric-pressure, microwave-induced plasma (MIP) torch operating in nitrogen. The plasma is operated at 2.45 GHz at an input power of 900 W with 50 W reflected, and inner and annular auxiliary nitrogen flow rates of 1 slpm each, and annular outer gas nitrogen flow rates of 13 and 25 slpm. Iron is introduced to the inner flow at a concentration of 200 ppm in a 1% HNO3 solution. Measured relative emission intensities of Fe I emission lines in the band between 370.56 and 376.72 nm are used to determine Texc using a fitting method assuming Boltzmann equilibrium. NH radical A( 3 Π)–X( 3 Σ ) spectra are also employed (in the band between approximately 335 and 343 nm) to determine Trot by comparing measured spectra with spectra calculated using the Specair software. The presence of overlapping spectral features from the N2 (C-B) second positive band near 337 nm are accounted for by activating these transitions in Specair in addition to the NH transitions. Good agreement between the Texc of Fe and Trot of NH is observed, indicating a local thermodynamic equilibrium (LTE) condition. These temperatures range from approximately 5000 K near the inner gas flow injector to approximately 4000 K at a distance of 25 mm downstream of the injector. The temperatures do not change significantly as a function of the outer gas flow rate.

Summary form only given. Low-pressure microwave-excited microplasmas1 are promising sources of VUV photons for a variety of applications, including photoionization for mass spectrometry. A split-ring resonator microstrip architecture can be used to initiate and sustain these microplasmas using the extremely high electric field generated in the sub-millimeter gap between electrodes. The VUV flux, primarily the result of resonance radiation following electronic excitation of rare gas atoms, is a sensitive function of the distribution of electron energies. Direct measurement of the electron energy distribution (EED) could provide critical insight into the physics of the microplasma operation. We present Thomson scattering measurements of the EED in a split-ring resonator argon microplasma operating at 2.5 GHz and approximately 1 Torr. The diagnostic consists of a Q-switched Nd:YAG laser operating at 532 nm. Thomsonscattered light is collected with a high throughput (f/2) triple grating imaging spectrometer and an intensified CCD camera gated to the laser pulses. Stray and Rayleigh-scattered laser light, which can exceed the intensity of the Thomsonscattered light by factors of over 105, is filtered out using a mask placed between the first two gratings, which are operated in subtractive mode. Other available diagnostics include VUV flux measured using a vacuum UV monochromator. Plasma parameters are measured as a function of gas flow rate, absorbed microwave power, and spatial location both within the plasma cavity and in the downstream plume. Experimental results of the EED and VUV flux are compared with computational modeling using the Hybrid Plasma Equipment Model (HPEM).2 In this model, the EED and radiation transport are computed using Monte Carlo simulations, and neutral gas and plasma transport are addressed using fluid techniques. These experimental and computational modeling results provide a means for optimizing the VUV flux produced by the source.

S | Carcinogenesis & Cancer Genetics 074 Bullous leukemia cutis in a patient with T-cell prolymphocytic leukemia Q Jiang, S Siu, S Onder Alpdogan, A Gochoco, J Gong, J Lee and J Sahu 1 Dermatology, Thomas Jefferson University, Philadelphia, PA, 2 Pathology, Thomas Jefferson University, Philadelphia, PA and 3 Medical Oncology, Thomas Jefferson University, Philadelphia, PA T-cell prolymphocytic leukemia (T-PLL) is a rare neoplasm of mature T lymphocytes. Cutaneous involvement, e.g., leukemia cutis (LC), is a characteristic symptom of T-PLL and appears in up to one-third of cases. LC may follow, precede or occur concomitantly with the diagnosis of systemic leukemia, however, vesiculo-bullous LCs are rare. So far, few were reported in chronic lymphocytic leukemia, but none in T-PLL. T-PLL is a relatively unknown disease in the field of dermatology, and moreover, variable leukemic cutaneous manifestations, especially the non-specific lesions of bullous LC, make it clinically difficult to distinguish from other non-specific lesions. We report here a case of leukaemia cutis with vesiculo-bullous lesions in a patient who was recently diagnosed with T-PLL and has been on chemotherapy. A skin biopsy specimen showed dense infiltration of small lymphocytes in the dermis, and subsequent immunogenotyping confirmed the presence of leukemia cells in the same patterns of previous biopsies of the lymph node. To our knowledge, this is the first report of vesiculo-bullous LC in a patient with T-PLL. LC is an indicator of poor prognosis and often requires more aggressive therapies. Proper diagnosis of LC is essential because it can alter the appropriate treatment for a patient. S14 Journal of Investigative Dermatology (2016), Volume 136 075 Ephrin-A loss in cutaneous squamous cell carcinoma progression and metastasis J Zheng, B Perez White, N Kaplan, A Petty, Z Zhao, K Honda, M Denning, M Blumenberg, S Getsios and B Wang 1 Dermatology, Northwestern U., Chicago, IL, 2 Case Western Reserve U., Cleveland, OH, 3 Loyola U., Chicago, IL and 4 New York U., New York, NY Glycophosphatidylinositol-linked ephrin-A proteins target EphA receptor tyrosine kinases (RTKs) to promote keratinocyte differentiation and maintain tissue homeostasis. Accordingly, genetic ablation of EphA2, a major epidermal EphA subtype, increases susceptibility to chemically induced skin carcinogenesis in mice. Defining the corresponding role of ligands for EphA2 in skin cancer has been more cumbersome as the three ephrin-A genes (efna1, efna3, efna4) proximal to the epidermal differentiation complex gene cluster are each prominently expressed in skin. We met this challenge by engineering a triple efnA1/3/4 knock-out mouse (efnA-TKO mice) that reflects the pattern of reduced efnA gene expression found in mouse and human cutaneous SCCs. Skin tumors were evident earlier and grew faster in mice lacking these three ephrin-A ligands or EphA2. While histologically benign papillomas were prominent in EphA2-deficient mice, efnA-TKO mice developed invasive squamous cell carcinomas that metastasized to the lymph nodes and lungs within 25 weeks of DMBA-TPA treatment. Using primary mouse and human cell culture models, we found that ephrin-A proteins operate within the epidermis by targeting EphA2 to limit keratinocyte migration. We also illustrated a key tumor suppressive role for ephrin-A ligands in the surrounding tumor microenvironment by re-introducing isogenic tumor cell lines into the skin of wild-type or efnA-TKO mice. Importantly, the invasive phenotype of efnA-TKO mouse tumor cell lines was normalized by genetic reintroduction of efnA3. Integrating our findings from human tumors, mouse models, and primary cell cultures provides strong support for the notion that ephrins operate within tumor cells and also in the microenvironment to suppress skin cancer growth and metastasis. 076 Senescent fibroblasts enhance squamous cell carcinoma progression through secretion of Chemerin and activation of MAPK pathway V Farsam, A Basu, M Gatzka, M Wlaschek, N Treiber, MA Mulaw, T Lucas, S Kochanek and K Scharffetter-Kochanek 1 Department of Dermatology and Allergic Diseases, University of Ulm, Ulm, Germany, 2 Institute of Experimental Cancer Research, University of Ulm, Ulm, Germany and 3 Department of Gene Therapy, University of Ulm, Ulm, Germany Aging is associated with an increased risk of cutaneous squamous cell carcinoma (cSCC) partly due to the accumulation of mutations in stem/progenitor cells and partly due to the acquisition of a senescence-associated secretory phenotype (SASP) by senescent fibroblasts in dermal stroma. However, the mechanisms underlying the SASP-induced cSCC progression are not sufficiently understood. We investigated the SASP effect of senescent human dermal fibroblasts on cSCC cell motility in vitro using Transwell migration assay. Conditioned media (CM) of senescent fibroblasts significantly increased the migration of cSCC lines in comparison to young CM. Using RT-qPCR and specific ELISA, high levels of Chemerin transcripts and protein were found in senescent compared to young fibroblasts. An increase in Chemerin immunostaining in dermal fibroblasts of skin sections from old healthy individuals were observed as opposed to almost absent Chemerin immunostaining in young skin. Enhanced expression of Chemerin receptor CCRL2 was detected in cSCC lines when compared to normal keratinocytes. Increased CCRL2 was also confirmed with immunostaining of skin biopsies derived from patients suffering from cSCC. Recombinant human (rh) Chemerin enhanced the migration of cSCC lines in a concentration-dependent manner, while silencing Chemerin in senescent fibroblasts via siRNAs reduced cSCC migration. Chemerin was found to activate mitogen-activated protein kinase (MAPK) signaling pathway. Of note, inhibition of MAPK signaling pathway with chemical inhibitors impaired SASP-induced migration of cSCC cells in response to senescent fibroblast CM and rh Chemerin. In aggregate, these previously unreported data suggest that senescent fibroblasts may facilitate tumor progression through Chemerin-mediated activation of MAPK pathway in cSCC cells. 077 The role of intra-abdominal adipose tissue in UVB-induced skin cancer J Bernard and B Bullard Pharmacology and Toxicology, Michigan State University, East Lansing, MI Recent research suggests that a high-fat diet (HFD) and/or obesity (increased adiposity) are key players in the pathogenesis and prognosis of many common cancers. However the molecular changes induced by adipose tissue (AT) that actually enhance cancer development are poorly understood. Our previous studies indicated that decreasing visceral (intraabdominal) AT by surgical removal of the parametrial fat pads inhibited UVB-induced carcinogenesis in SKH-1 mice fed a HFD indicating that the parametrial AT from mice fed a HFD played a role in skin carcinogenesis. The purpose of this study was to investigate how a HFD may influence the intrinsic properties of the parametrial AT to induce UVB-induced skin tumor formation. We developed a system where molecules released and filtered from AT (fat tissue filtrate) stimulate JB6 P cell proliferation and transformation. The mouse BALB/c skin epithelial JB6 P cell line is a well-characterized model for neoplastic transformation that is responsive to tumor promoter-induced transformation growth in soft agar and is uniquely suited for studying tumor promotion and promotion-relevant molecular events in vitro. Our data demonstrate that fat tissue filtrate made from the parametrial ATof obese mice fed a HFD had 160% more transforming activity than that from mice fed a LFD (P

The longitudinal relaxation time of (79)Br nuclei in KBr is field independent, between 4.7 T and 14.1 T. The results suggest that inconsistencies in the literature are due to differences in the experimental set-ups. The limitations of KBr as temperature calibrant are discussed.

The accurate temperature measurement of solid samples under magic-angle spinning (MAS) is difficult in the cryogenic regime. It has been demonstrated by Thurber et al. (J. Magn. Reson., 196 (2009) 84-87) [10] that the temperature dependent spin-lattice relaxation time constant of (79)Br in KBr powder can be useful for measuring sample temperature under MAS over a wide temperature range (20-296 K). However the value of T(1) exceeds 3 min at temperatures below 20K, which is inconveniently long. In this communication, we show that the spin-lattice relaxation time constant of (127)I in CsI powder can be used to accurately measure sample temperature under MAS within a reasonable experimental time down to 10 K.

Microplasma sources typically take advantage of pd (pressure × size) scaling by increasing pressure to operate at dimensions as small as tens of microns. In many applications, low pressure operation is desirable, which makes miniaturization difficult. In this paper, the characteristics of low pressure microplasma sources excited by microwave power are discussed based on results from experimental and computational studies. The intended application is production of VUV radiation for chemical analysis, and so emphasis in this study is on the production of resonant excited states of rare gases and radiation transport. The systems of interest operate at a few to 10 Torr in Ar and He/Ar mixtures with cavity dimensions of hundreds of microns to 1 mm. Power deposition is a few watts which produces fractional ionization of about 0.1%. We found that production of VUV radiation from argon microplasmas at 104.8 nm and 106.7 nm saturates as a function of power deposition due to a quasi-equilibrium that is established between the electron temperature (that is not terribly sensitive to power deposition) and the population of the Ar(4s) manifold.

In this paper we investigate the feasibility of creating a high‐density ∼ 1012−1014 cm−3, large volume seed plasma in air constituents by laser (300 mJ, 20(±2) ns) preionization of an organic gas seeded in high‐pressure gas mixtures and then sustained by efficient absorption of rf power (1–25 kW pulsed) through inductive coupling of the wave fields. A multi‐turn helical antenna is used to couple radio‐frequency power through a capacitive matching network. A 105 GHz interferometer is employed to obtain the plasma density in the presence of high collisionality utilizing phase shift and amplitude attenuation data. TMAE Plasma decay mechanisms with and without the background gas are examined.

We report a solid-state NMR study of the anisotropic nuclear spin interactions in H 2 O@C 60 at room temperature. We find evidence of significant dipole–dipole interactions between the water protons, and also a proton chemical shift anisotropy (CSA) interaction. The principal axes of these interaction tensors are found to be perpendicular. The magnitude of the CSA is too large to be explained by a model in which the water molecules are partially aligned with respect to an external axis. The evidence indicates that the observed CSA is caused by a distortion of the geometry or electronic structure of the fullerene cages, in response to the presence of the endohedral water.

Static and magic-angle spinning (11)B nuclear magnetic resonance (NMR) data at 4.7 T and 8.5 T have been obtained under cryogenic conditions on a diluted sample of magnesium diboride powder in the normal and superconducting state. The data provide accurate information on the magnetic shift and longitudinal relaxation time down to a temperature of 8 K, with a resolution improvement over the entire temperature range. The onset of superconductivity is unaffected by the sample rotation, as revealed by a steep variation of the magnetic shift just below the critical temperature.

Neutral depletion effects are observed in a steady-state flowing argon helicon plasma with a magnetic nozzle for high rf input powers (up to 3kW). Noninvasive diagnostics including 105GHz microwave interferometry and optical spectroscopy with collisional-radiative modeling are used to measure the electron density (ne), electron temperature (Te), and neutral density (nn). A region of weak neutral depletion is observed upstream of the antenna where increasing rf power leads to increased electron density (up to ne=1.6×1013cm−3) while Te remains essentially constant and low (1.7–2.0eV). The downstream region exhibits profound neutral depletion (maximum 92% line-averaged ionization), where Te rises linearly with increasing rf power (up to 4.9eV) and ne remains constrained (below 6.5×1012cm−3). Flux considerations indicate accelerated plasma flow (Mach 0.24) through the antenna region due to an axial pressure gradient with reduced collisional drag from neutral depletion.

A laser initiation and radio frequency (rf) sustainment technique has been developed and improved from our previous work to create and sustain large-volume, high-pressure air and nitrogen plasmas. This technique utilizes a laser-initiated, 15 mTorr partial pressure tetrakis (dimethylamino) ethylene seed plasma with a 75 Torr background gas pressure to achieve high-pressure air/nitrogen plasma breakdown and reduce the rf power requirement needed to sustain the plasma. Upon the laser plasma initiation, the chamber pressure is raised to 760 Torr in 0.5 s through a pulsed gas valve, and the end of the chamber is subsequently opened to the ambient air. The atmospheric-pressure plasma is then maintained with the 13.56 MHz rf power. Using this technique, large-volume (1000 cm3), high electron density (on the order of 1011–12 cm−3), 760 Torr air and nitrogen plasmas have been created while rf power reflection is minimized during the entire plasma pulse utilizing a dynamic matching method. This plasma can project ...