Wideband saturable absorption in few-layer molybdenum diselenide (MoSe2) for Q-switching Yb-, Er- and Tm-doped fiber lasers.

We fabricate a free-standing molybdenum diselenide (MoSe2) saturable absorber by embedding liquid-phase exfoliated few-layer MoSe2 flakes into a polymer film. The MoSe2-polymer composite is used to Q-switch fiber lasers based on ytterbium (Yb), erbium (Er) and thulium (Tm) gain fiber, producing trains of microsecond-duration pulses with kilohertz repetition rates at 1060 nm, 1566 nm and 1924 nm, respectively. Such operating wavelengths correspond to sub-bandgap saturable absorption in MoSe2, which is explained in the context of edge-states, building upon studies of other semiconducting transition metal dichalcogenide (TMD)-based saturable absorbers. Our work adds few-layer MoSe2 to the growing catalog of TMDs with remarkable optical properties, which offer new opportunities for photonic devices.

Tunable Q-switched fiber laser based on saturable edge-state absorption in few-layer molybdenum disulfide (MoS2).

We fabricate a few-layer molybdenum disulfide (MoS2) polymer composite saturable absorber by liquid-phase exfoliation, and use this to passively Q-switch an ytterbium-doped fiber laser, tunable from 1030 to 1070 nm. Self-starting Q-switching generates 2.88 µs pulses at 74 kHz repetition rate, with over 100 nJ pulse energy. We propose a mechanism, based on edge states within the bandgap, responsible for the wideband nonlinear optical absorption exhibited by our few-layer MoS2 sample, despite operating at photon energies lower than the material bandgap.

Developmentally regulated expression of T cell receptor beta chain variable domains in immature thymocytes.

A minor subset of immature (CD4-,8-) thymocytes that lack expression of the B2A2 antigen was found to express low levels of surface TCR protein as detected by mAbs F23.1 and KJ16 (reacting with protein products of the V beta 8 gene family). Interestingly, F23.1/KJ16 determinants were expressed on a two- to three-fold higher proportion of B2A2- thymocytes than mature lymph node T cells in four independent haplotypes. When expanded in short-term culture with PMA and calcium ionophore, B2A2- thymocytes retained their overexpression of F23.1/KJ16 determinants and showed a fivefold elevated level (relative to lymph node) of V beta 8-specific mRNA. Taken together, these findings suggest that expression of TCR V beta genes, like Ig genes, is developmentally regulated.

Facilitation of spindle-burst sleep by conditioning of electroencephalographic activity while awake.

A slow-wave electroencephalographic rhythm recorded from the sensorimotor cortex of the waking cat has been correlated behaviorally with the suppression of movement. Facilitation of this rhythm through conditioning selectively enhances a similar pattern recorded during sleep, the familiar spindle burst. The training also produced longer epochs of undisturbed sleep. The specific neural mechanism manipulated during wakefulness appears to function also in sleep and to be involved with the regulation of phasic motor behavior.

Distribution of Lyb-4.1 and other membrane antigens on murine lymphoid tumors.

The distribution of membrane antigens on 6 DBA/2-derived tumors (L1210, L5178Y, P815, ABLS 11, ABLS 12, and ABLS 13) was studied by direct cytotoxicity and quantitative absorption assays. Lyb-4.1 antigen was found solely on the L1210 tumor. Iad antigens were absent from all tumors, and H-2Kd and H-2Dd antigens were present on all tumors. Immunoglobulin was adsorbed to the ascites tumors and lost after 3 days or more in tissue culture. These studies were performed to characterize the distribution of DBA/2 membrane antigens on DBA/2-derived tumors as a base line for functional and chemical studies with these tumors and with their solubilized proteins.

Heterogeneity in the membrane proteins of human lymphoid cell lines as seen in sodium dodecyl sulfate-polyacrylamide electrophoresis slab gels.

The proteins of [35S]methionine-labeled membranes of six human lymphoid cell lines were examined by electrophoresis in sodium dodecyl sulfate-polyacrylamide gradient slab gels in order to identify molecular differences among these tumors. The lymphoid cells were internally labeled with [35S]methionine, their membranes were isolated, and the reduced and alkylated membrane proteins were treated electrophoretically in sodium dodecyl sulfate-polyacrylamide gradient slab gels. The gel patterns of over 100 membrane proteins per cell were highly complex but reproducible and, in that sense, constituted fingerprints of the individual tumors. Several proteins occurred uniquely on one or a few tumors. Some protein bands were identified to be serologically recognized membrane antigens by electrophoresis of immunopurified antigen in parallel to membrane samples. p44,12, a complex of proteins with molecular weights of 44,000 and 12,000 (HLA-A and -B antigens and beta2-microglobulin), and p29,34, (HLA-D antigen) were identified in this manner. High-resolution sodium dodecyl sulfate-polyacrylamide gradient gel electrophoresis can be used to catalog and describe lymphocyte membrane proteins and perhaps to identify subsets of lymphoid cancers.

Internal synthesis of p23,30 by several lymphoid malignancies.

The aim of this study was to prove the internal synthesis of p23,30 antigen (HLA-D related determinant) on human leukemias and lymphomas on which it has been detected with complement-dependent cytotoxic assays. Murine Ia antigens similar to p23,30 antigen are found on many subsets of cells in the mouse (B lymphocytes, macrophages, allogeneically activated T lymphocytes) and on intercellularly transferred immunoregulatory molecules, which may be adsorbed to other cells. The question exists whether the p23,30 antigen, which occurs on a wide range of human leukemias, is internally synthesized by these tumors or, in some instances, is synthesized by normal lymphocytes and is adsorbed to the leukemic cells. The expression of p23,30 antigen on a limited series of human leukemias and lymphomas was detected by a complement dependent, cytotoxicity assay. The internal synthesis of p23,30 antigen and p44,12 (HLA-A and -B antigens and beta2-microglobulin) was confirmed by immunoprecipitation and these antigens from [35S]methionine labeled, detergent solubilized membranes of tumor cells. In each instance, the synthesis of p23,30 antigen by the malignant cells was confirmed. The distribution of p23,30 antigen (and 1a antigen) on subsets of normal cells and in immunoregulatory molecules was reviewed. In view of these findings, the role of p23,30 antigen in the diagnosis of subsets of human hematologic malignancies was reconsidered.

Yb- and Er-doped fiber laser Q-switched with an optically uniform, broadband WS2 saturable absorber.

We demonstrate a ytterbium (Yb) and an erbium (Er)-doped fiber laser Q-switched by a solution processed, optically uniform, few-layer tungsten disulfide saturable absorber (WS2-SA). Nonlinear optical absorption of the WS2-SA in the sub-bandgap region, attributed to the edge-induced states, is characterized by 3.1% and 4.9% modulation depths with 1.38 and 3.83 MW/cm(2) saturation intensities at 1030 and 1558 nm, respectively. By integrating the optically uniform WS2-SA in the Yb- and Er-doped laser cavities, we obtain self-starting Q-switched pulses with microsecond duration and kilohertz repetition rates at 1030 and 1558 nm. Our work demonstrates broadband sub-bandgap saturable absorption of a single, solution processed WS2-SA, providing new potential efficacy for WS2 in ultrafast photonic applications.

CMOS integration of inkjet-printed graphene for humidity sensing.

We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things.

A method for transition smoothing of sleep--waking states.

A method was developed for sequential redistribution of short-duration sleep--waking states into the long-duration behavioral state(s) that surrounds these intervals. This methodological approach is useful in determination of general sleep--waking patterns such as state durations, interstate intervals, and sleep--waking cycles. The redistribution sequences had no effect on total amount of sleep or waking categories, but did decrease stage 1 with successive redistribution steps. Examination of the slope of the curve (number of occurrences or mean epoch duration divided by successive redistributions) can be used to determine the appropriate "smoothing" for electroencephalogram (EEG) state data via location of the breakpoint in the curve. The low-pass redistribution technique has been particularly useful for smoothing large volumes of EEG state data for subsequent analyses without significantly changing the various sleep-waking states.

Effect of transforming growth factor beta on the EL4 thymoma variant EL4/6.1: dissociation of inhibition of proliferation from expression of IL-1 and IL-2 receptors.

In order to further characterize the action of transforming growth factor beta (TGF-beta) on lymphoid cells, we investigated the effects of porcine TGF-beta 1 and -2 on the IL-1 sensitive EL4/6.1 thymoma cell line. The proliferation of EL4/6.1 thymoma cells was inhibited by TGF-beta 1 and TGF-beta 2 (1 ng/ml) to a similar degree, the population doubling time was increased by 50-60%, total inhibition was not achieved. This decrease of proliferation was associated with an increase of the number of cells in the G0/G1 compartment of the cell cycle. TGF-beta-mediated inhibition could not be overcome by adding exogenous rIL-1 nor was the binding capacity for IL-1 reduced. In addition, TGF-beta did not interfere with the induction of IL-2 receptors by a combination of Ionomycin+PMA+IL-1. The data suggest that TGF-beta mediated inhibition of thymocyte/lymphocyte proliferation is not associated with an inhibition of the expression or the induction of expression of IL-2 or IL-1 receptors.

Acute heroin abstinence in man: IV. Sleep--waking state contingencies.

This study investigated the effect of acute heroin withdrawal on the pattern of sleep--waking state sequences. Subjects included drug-dependent patients using pure heroin and drug-free controls. Electrophysiological data were recorded on a 24-hour per day basis for the first 5 - 7 days of withdrawal. EEG records were scored according to standard criteria. Marked increases in the sequential state changes occurred during withdrawal when progressing from awake-with-alpha, stage I, stage II and rapid eye movement (REM) sleep to the awake state. Heroin withdrawal also caused significant decreases in sequential state changes when proceeding from waking or light sleep states into deeper sleep states or into REM sleep. This study revealed that heroin withdrawal caused more abrupt transitions from quiet awake or sleeping conditions into the awake state and impeded progression into slow wave or REM sleep states.

Acute heroin abstinence in man: II. Alterations in rapid eye movement (REM) sleep.

The purpose of this study was to examine the effects of withdrawal from heroin upon rapid eye movement (REM) sleep. Subjects included both heroin-dependent patients and drug-free controls. The drug users were young males who had an average daily intake of approximately 973 mg of 92 - 98% pure heroin before entering the study. All electrophysiological data were obtained via a telemetry system on a 24-hour per day basis for 5 to 7 consecutive days. EEG records were scored into the standard awake and sleep states. Results showed a marked decrease in total amount of REM sleep during heroin withdrawal. This total decrease was associated with a decrease in duration of individual REM episodes and a large decrease in the number of occurrences of REM sleep. The heroin-dependent patients during withdrawal also showed a prolonged latency from sleep onset to first REM episode and a reduced number of REM shifts per 24-hour period. No significant difference in REM sleep interval was observed between the control subjects and drug users. Some of the overt behavioral characteristics associated with heroin withdrawal may be indirectly related to the concurrent loss in REM sleep as observed in this study.

Acute heroin abstinence in man: I. Changes in behavior and sleep.

The purpose of this study was to examine overt behavioral characteristics and sleep during acute heroin abstinence in man. Both heroine-dependent patients and drug-free control subjects were observed and monitored on a 24-hour per day basis for 5 to 7 days. Observational data were analyzed for frequency of occurrence of various behaviors including the signs and symptoms of withdrawal. Electroencephalographic (EEG) data were scored into awake and sleep stages according to standard techniques. The heroin-dependent subjects generally displayed a higher number of observations across all recording days as compared to the controls. In addition, the signs and symptoms of withdrawal for these patients peaked on day 1 or day 2 and then declined over the remaining recording days. The EEG state data showed an increase in waking and decrease in both slow wave and REM sleep during acute heroin withdrawal. Total sleep was maximally suppressed on withdrawal days 2 and 3 and was still below normal control values on withdrawal days 5 - 7. REM sleep was more disrupted than slow-wave sleep during withdrawal from heroin. Results of this study indicate that heroin withdrawal produces a differential action upon central nervous system structures responsible for the various states of sleep, waking and related behaviors.

Acute heroin abstinence in man. III. Effect upon waking and slow wave sleep.

The purpose of this study was to evaluate the effects of acute heroin withdrawal on waking behavior and slow wave sleep. Data were collected from drug-dependent patients who were using pure heroin and from drug-free controls. All data were recorded on a 24-hour per day basis for 5 - 7 consecutive days. EEG records were manually scored according to standard criteria. The heroin-dependent patients during withdrawal showed approximately a 26% decrease in slow wave sleep and an 18% increase in waking behavior. The awake state in the heroin-dependent patients during withdrawal also displayed an increase in number of episodes and number of state shifts, and a decrease in duration and sleep onset latency. In addition, the slow wave sleep categories during withdrawal generally showed an increase in sleep onset latency and interstate interval and a decrease in number of episodes. These results indicate that heroin withdrawal is associated with a marked disruption of the central nervous system mechanisms responsible for maintenance of the normal sleep--waking cycle. Analyses of the pattern of this disruption will further aid in understanding the withdrawal syndrome.

Recurring bacterial infection in a teenager: an Ethiopian case of common variable immunodeficiency revealed by the occurrence of rheumatoid arthritis.

A case of common variable immunodeficiency observed in an Ethiopian 13 year old girl who, from the age of 9 months, suffered from repeated, severe bacterial infections, but overcame viral infections normally, is reported. The immune defect bore upon the terminal stage of the differentiation of the B-lymphocytes, whose number was normal but which were unable to synthesize immunoglobulin in vitro. Replacement therapy with gammaglobulins controlled infection. The differential diagnosis of recurrent bacterial infection in the tropical context and means of early diagnosis are discussed.