Inversionless light amplification and optical switching controlled by state-dependent alignment of molecules

We propose a method to achieve amplification without population inversion by anisotropic molecules whose orientation by an external electric field is state-dependent. It is based on decoupling of the lower-state molecules from the resonant light while the excited ones remain emitting. The suitable class of molecules is discussed, the equation for the gain factor is derived, and the magnitude of the inversionless amplification is estimated for the typical experimental conditions. Such switching of the sample from absorbing to amplifying via transparent state is shown to be possible both with the aid of dc and ac control electric fields.Comment: AMS-LaTeX v1.2, 4 pages with 4 figure

Scavenger receptors and β-glucan receptors participate in the recognition of yeasts by murine macrophages

Objectives: Numerous receptors have been implicated in recognition of pathogenic fungi by macrophages, including the $\beta$-glucan receptor dectin-1. The role of scavenger receptors (SRs) in anti-fungal immunity is not well characterized. Methods: We studied uptake of unopsonized Saccharomycetes cerevisiae (zymosan) and live Candida albicans yeasts as well as zymosan-stimulated $H_2O_2$ production in J774 macrophage-like cells and peritoneal exudate macrophages (PEMs). The role of different receptors was assessed with the use of competitive ligands, transfected cells and receptor-deficient macrophages. Results: The uptake of zymosan by untreated J774 cells was mediated approximately half by SRs and half by a $\beta$-glucan receptor which was distinct from dectin-1 and not linked to stimulation of $H_2O_2$ production. Ligands of $\beta$-glucan receptors and of SRs also inhibited uptake of C. albicans by macrophages (J774 cells and PEMs). In macrophages pretreated with a CpG motif-containing oligodeoxynucleotide (CpG-ODN) the relative contribution of SRs to yeast uptake increased and that of $\beta$-glucan receptors decreased. Whereas the class A SR MARCO participated in the uptake of both zymosan and C. albicans by CpG-ODN-pretreated, but not untreated macrophages, the related receptor SR-A/CD204 was involved in the uptake of zymosan, but not of C. albicans. The reduction of zymosan-stimulated $H_2O_2$ production observed in DS-pretreated J774 cells and in class A SRs-deficient PEMs suggest that class A SRs mediate part of this process. Conclusions: Our results revealed that SRs belong to a redundant system of receptors for yeasts. Binding of yeasts to different receptors in resting versus CpG-ODN-pre-exposed macrophages may differentially affect polarization of adaptive immune responses

The effects of β-glucan on human immune and cancer cells

Non-prescriptional use of medicinal herbs among cancer patients is common around the world. The alleged anti-cancer effects of most herbal extracts are mainly based on studies derived from in vitro or in vivo animal experiments. The current information suggests that these herbal extracts exert their biological effect either through cytotoxic or immunomodulatory mechanisms. One of the active compounds responsible for the immune effects of herbal products is in the form of complex polysaccharides known as β-glucans. β-glucans are ubiquitously found in both bacterial or fungal cell walls and have been implicated in the initiation of anti-microbial immune response. Based on in vitro studies, β-glucans act on several immune receptors including Dectin-1, complement receptor (CR3) and TLR-2/6 and trigger a group of immune cells including macrophages, neutrophils, monocytes, natural killer cells and dendritic cells. As a consequence, both innate and adaptive response can be modulated by β-glucans and they can also enhance opsonic and non-opsonic phagocytosis. In animal studies, after oral administration, the specific backbone 1→3 linear β-glycosidic chain of β-glucans cannot be digested. Most β-glucans enter the proximal small intestine and some are captured by the macrophages. They are internalized and fragmented within the cells, then transported by the macrophages to the marrow and endothelial reticular system. The small β-glucans fragments are eventually released by the macrophages and taken up by other immune cells leading to various immune responses. However, β-glucans of different sizes and branching patterns may have significantly variable immune potency. Careful selection of appropriate β-glucans is essential if we wish to investigate the effects of β-glucans clinically. So far, no good quality clinical trial data is available on assessing the effectiveness of purified β-glucans among cancer patients. Future effort should direct at performing well-designed clinical trials to verify the actual clinical efficacy of β-glucans or β-glucans containing compounds

The upgrade of the ALICE TPC with GEMs and continuous readout

The upgrade of the ALICE TPC will allow the experiment to cope with the high interaction rates foreseen for the forthcoming Run 3 and Run 4 at the CERN LHC. In this article, we describe the design of new readout chambers and front-end electronics, which are driven by the goals of the experiment. Gas Electron Multiplier (GEM) detectors arranged in stacks containing four GEMs each, and continuous readout electronics based on the SAMPA chip, an ALICE development, are replacing the previous elements. The construction of these new elements, together with their associated quality control procedures, is explained in detail. Finally, the readout chamber and front-end electronics cards replacement, together with the commissioning of the detector prior to installation in the experimental cavern, are presented. After a nine-year period of R&D, construction, and assembly, the upgrade of the TPC was completed in 2020.publishedVersio

CARS investigation of collisional shift of the hydrogen Q-branch transitions by water at high temperatures

A high-resolution (∼0.1 cm−1) spectroscopic method based on the application of a Fabry–Pérot interferometer to the spectral analysis of the coherent anti-Stokes Raman scattering (CARS) signal from an individual Raman transition was used to obtain single-shot spectra of hydrogen Q-branch transitions directly in the flame of a pulsed, high-pressure H2/O2 combustion chamber. Simultaneously with the Fabry–Pérot pattern, a broadband CARS spectrum of the complete H2Q -branch structure was recorded in order to measure the temperature of the probe volume. During every cycle of the combustion chamber, a pressure pulse together with single-shot CARS spectra, providing information on individual line shapes and medium temperature, was recorded. On the basis of the experimental data, the temperature dependences of lineshift coefficients for several Q-branch lines of hydrogen molecules under collisions with water molecules were determined in the temperature range 2100 < T < 3500 K, and an empirical ‘fitting law’ for H2H2O lineshift coefficients is proposed

CARS Temperature Measurement in a LOX/CH4 Spray Flame

Coherent anti-Stokes Raman scattering (CARS) spectroscopy has been used to investigate cryogenic liquid oxygen/gaseous methane (LOX/CH4) flames on a medium-size test facility at a pressure of 0.24 MPa and mass flow of 0.025 kg/s. Single-shot, broadband CARS spectra with simultaneous detection of the Q-branches of hydrogen and water molecules were recorded with good signal-to-noise ratio. Temperature was deduced from the H2 and H2O CARS profiles. The spatial temperature distribution in a comparatively harsh environment has been measured successfully. The measurements took place in the windowed combustion chamber of the DLR M3 test facility, aiming to provide data for validation of rocket combustor modeling

Untersuchung zur Temperaturverteilung mittels CARS-Thermometrie in einer Modellstaubrennkammer beim Abbrand von Festbrennstoffplatten

Der Verbrennungsprozeß von Festbrennstoffen mit und ohne Borpartikel-Zusatz wurde in einer ebenen Stufenbrennkammer mit optischem Zugang mittels der Kohärenten anti-Stokes Raman Spektroskopie (CARS) untersucht. Die in der Rezirkulationszone hinter der Stufe und die in der brennstoffreichen Zone unmittelbar über der Festbrennstoffplatte ermittelten CARS-Spektren zeigen starke Interferenzen mit dem Swan-Bandensystem von C2-Radikalen. Die in der äußeren Zone der reagierenden Grenzschichtströmung ermittelten Temperaturhistogramme haben teilweise stark ausgeprägte bimodale Temperaturverteilungen. Dies zeigt den intensiven Vermischungsprozeß und das Eindringen kälterer Gase aus der äußeren Strömungsregion in die äußere Zone der reagierenden Grenzschichtströmung durch wirbelförmige Strukturen

Supply Chains: a network perspective

The combustion process in a high-pressure gaseous methane/gaseous oxygen rocket model combustor was investigated by means of optical and laser spectroscopic measurements as well as numerical simulations. The combustor was operated at a pressure of 1.0 MPa and at two mixture ratios (O/F = 1 and 2). OH∗ chemiluminescence imaging was applied for a qualitative analysis of the position and shape of the flame brush. For quantitative results, coherent anti-Stokes Raman spectroscopy (CARS) was applied to measure the spatial temperature distribution inside the combustion chamber. H2 and H2O molecules were probed simultaneously using two synchronized broadband CARS setup. Temperatures were derived from the H2 and H2O single-shot CARS spectra. Furthermore, the Transported Partially Stirred Reactor (TPaSR) model has been employed for simulations at the same operating conditions. The comparison of the numerical simulations to the experimental temperature distributions shows already qualitative agreement although further improvements are still needed