Single-cell RNA sequencing coupled to TCR profiling of large granular lymphocyte leukemia T cells.

T-cell large granular lymphocyte leukemia (T-LGLL) is a lymphoproliferative disease and bone marrow failure syndrome which responds to immunosuppressive therapies. We show single-cell TCR coupled with RNA sequencing of CD3+ T cells from 13 patients, sampled before and after alemtuzumab treatments. Effector memory T cells and loss of T cell receptor (TCR) repertoire diversity are prevalent in T-LGLL. Shared TCRA and TCRB clonotypes are absent. Deregulation of cell survival and apoptosis gene programs, and marked downregulation of apoptosis genes in CD8+ clones, are prominent features of T-LGLL cells. Apoptosis genes are upregulated after alemtuzumab treatment, especially in responders than non-responders; baseline expression levels of apoptosis genes are predictive of hematologic response. Alemtuzumab does not attenuate TCR clonality, and TCR diversity is further skewed after treatment. Inferences made from analysis of single cell data inform understanding of the pathophysiologic mechanisms of clonal expansion and persistence in T-LGLL.

Repopulation of nitrogen excited triplet state following laser-induced filamentation.

Laser-induced filamentation was used to study the dynamics of excited molecular nitrogen decay processes. It is well-known that upper excited nitrogen triplet states can be repopulated at time delays far longer than their fluorescence lifetimes. Examination of the time-resolved emission from several different species indicates that there are two major mechanisms acting to repopulate the N2(C(3)Πu) excited state. The results implicate dissociative electron recombination with the nitrogen cation dimer, N4(+), and energy pooling between two N2(A(3)Σu(+)) triplet states as the main pathways to repopulate the emissive upper triplet state. The densities of N2(A(3)Σu(+)) and free electrons produced during filamentation were measured under atmospheric pressures in nitrogen and estimated to be [N2(A(3)Σu(+))]0 = 3 × 10(15) cm(­3) and [e(­)]0 = 3 × 10(13) cm(­3). The methods outlined in this report could find significant utility in measuring the concentration profiles of these important reactive intermediates within laser-induced filaments produced under different conditions.

Standoff detection of nitrotoluenes using 213-nm amplified spontaneous emission from nitric oxide.

A method of standoff detection based on the observation of laser-induced fluorescence-amplified spontaneous emission (LIF-ASE) is described. LIF-ASE generates uniaxial intensity distributions of the observed fluorescence with the majority of intensity propagating along the excitation axis in both the forward and backward directions. The detection of bulk vapor at significant standoff distances is readily achieved. This method was used to detect NO directly and as a photoproduct after 213-nm excitation of 2-, 3-, and 4-nitrotoluene. The NO LIF-ASE spectra were studied as a function of buffer gas. These studies showed that the emission from different vibrational states was dependent upon the buffer gas used, suggesting that the populations of vibrational states were influenced by the environment. A similar sensitivity of the vibrational populations was observed when the different nitroaromatic precursors were used in nitrogen buffer gas. Such sensitivity to environmental influences can be used to distinguish among the different nitroaromatic precursors and facilitate the identification of the bulk vapor of these analytes.

Characterization of near-infrared low energy ultra-short laser pulses for portable applications of laser induced breakdown spectroscopy.

We report on the delivery of low energy ultra-short (<1 ps) laser pulses for laser induced breakdown spectroscopy (LIBS). Ultra-short pulses have the advantage of high peak irradiance even at very low pulse energies. This opens the possibility to use compact, rare-earth doped fiber lasers in a portable platform for point detection applications using LIBS for elemental analysis. The use of low energy ultra-short pulses minimizes the generation of a broad continuum background in the emission spectrum, which permits the use of non-gated detection schemes using very simple and compact spectrometers. The pulse energies used to produce high-quality LIBS spectra in this investigation are some of the lowest reported and we investigate the threshold pulse requirements for a number of near IR pulse wavelengths (785-1500 nm) and observe that the pulse wavelength has no effects on the threshold for observation of plasma emission or the quality of the emission spectra obtained.

Analysis of charge-transfer absorption and emission spectra on an absolute scale: evaluation of free energies, matrix elements, and reorganization energies.

The relationship between the absorption and emission spectra of the charge-transfer complexes formed between a series of methyl-substituted benzene donors with 1,2,4,5-tetracyanobenzene as acceptor in 1,2-dichloroethane was examined in detail. The association constants for charge-transfer complex formation and the emission quantum yields for these complexes were used to place the experimental absorption and emission spectra on absolute scales. The simultaneous analysis of these spectra is valid only when the Mulliken two-state model is justified. For several of the complexes included in this study the electron-transfer parameters, including the electronic coupling matrix elements, obtained from the analysis of the individual absorption and emission spectra are in close agreement. The simultaneous analysis of the combined absorption and emission spectra leads to a well-defined set of electron-transfer parameters for these complexes. In other complexes, where the two-state model does not apply because of the influence of localized excited states on the absorption spectrum, analysis of the absorption and emission spectra led to significantly different sets of electron-transfer parameters. It is demonstrated that the electronic coupling matrix elements are a very sensitive indicator of the influence of localized excited states on these spectra.