Passive Submillimeter-wave Stand-off Video Camera for Security Applications

We present the concept and experimental set-up of a passive submillimeter-wave stand-off imaging system for security applications. Our ambition is the design of an application-ready and user-friendly camera providing high sensitivity and high spatial resolution at video frame rates. As an intermediate step towards this goal, the current prototype already achieves a frame rate of 10 frames per second and a spatial resolution below 2 cm at 8 m distance. The camera is the result of a continuous development and a unique concept that yielded first high-resolution passive submillimeter-wave images provided by cryogenic sensors in May et al. (2007). It is based on an array of 20 superconducting transition-edge sensors operated at a temperature of 450 mK, a closed-cycle cooling system, a Cassegrain-type optics with a 50 cm main mirror, and an opto-mechanical scanner. Its outstanding features are the scanning solution allowing for high frame rates and the compact and integrated system design.     

Analysis and stereodifferentiation of linalool in Theobroma cacao and cocoa products using enantioselective multidimensional gas chromatography

Contents and enantiomeric distributions of linalool (3,7-dimethyl-1,6-octadien-3-ol) were investigated in raw and roasted cocoa beans (seeds of Theobroma cacao) of defined origin as well as in commercial products, such as cocoa powders or chocolates. The stereodifferentiation of linalool was achieved by enantioselective multidimensional gas chromatography using heptakis (2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin as chiral stationary phase. Simultaneous steam distillation–extraction at pH 7 allowed sample preparation without racemization of linalool. Cocoa beans contain linalool primarily as (S)-enantiomer. Model experiments and analyses of commercial products such as cocoa powders and chocolates revealed that technological procedures employed in the manufacturing of cocoa products do not result in significant changes of the original enantiomeric distribution of linalool.     

Rapid and simultaneous analysis of 16-<Emphasis Type="Italic">O</Emphasis>-methylcafestol and sterols as markers for assessment of green coffee bean authenticity by on-line LC-GC

An on-line LC-GC method for analysis of 16-O-methylcafestol (16-OMC) and total sterols in oils obtained from green beans of Coffea canephora (Robusta) and C. arabica (Arabica) has been developed. HPLC pre-separation of the transesterified lipids allows quantification of the content of 16-OMC. The fraction containing the sterols is transferred to on-line GC analysis. The results obtained for Arabica and Robusta samples were in good agreement with literature data obtained by classical analytical procedures. The method allows rapid and simultaneous determination of two markers (16-OMC and Δ⁵-avenasterol) proposed for authenticity assessment of coffee beans and overcomes time-consuming sample pretreatment steps.     

The inhibitory glycine receptor-simple views of a complicated channel

The strychnine-sensitive glycine receptor is the principal mediator of fast inhibitory synaptic transmission in the mammalian spinal cord and brain stem. As a member of the ligand-gated ion-channel family, it shares structural homology with the nicotinic acetylcholine, GABA(A/C) and serotonin 5-HT(3) receptors. Ion-channel activation and desensitisation are controlled by a variety of factors such as subunit composition, posttranslational modification, absence or presence of modulatory ions or other agents and possibly protein-protein interactions. Glycine-receptor mutations, either associated with the human motor disorder hyperekplexia or artificially introduced, have helped to define the regulatory domains of the receptor protein. In addition to their effects on glycine-receptor function, allelic variants of glycine-receptor genes may also affect biogenesis, assembly and degradation of the receptor.     

Synthesis and Structure of New Dimeric Cyclopentadienyl Titanium Fluorine–Oxygen Systems: [Cp*TiF(μ-F)(μ-OPOPh2)]2, [Cp*TiF(μ-F)(μ-OSO2-p-C6H4Me)]2 and [Cp*TiF2(μ-OMe)]2

The reactions of Cp*TiF₃ with Me₃SiOPOPh₂, Me₃SiOSO₂-p-C₆H₄Me, and Al(OMe)₃ resulted in the formation of the dimers [Cp*TiF(μ-F)(μ-OPOPh₂)]₂ 1 , [Cp*TiF(μ-F)(μ-OSO₂-p-C₆H₄Me)]₂ 2 , and [Cp*TiF₂(μ-OMe)]₂ 3 , respectively, in good yields. In contrast to the formation of 3 , Cp*TiF₃ reacts with Al(OH)₃ to afford the known tetramer [Cp*TiF(μ-O)]₄ 4 . The structures of 1–3 have been determined by X-ray crystallography; compounds 1 and 3 crystallize in the monoclinic space group P2₁/c and compound 2 in the monoclinic space group P2/n. Compound 1 is the first example of a dimeric Cp*-titanium phosphinate containing a fluorine ligand. The core of the dimeric structure of both 1 and 2 consists of two Ti atoms bridged by two fluorine atoms and two bidentate groups. In contrast, the dimeric structure of 3 consists of two Ti atoms bridged only by two methoxy groups. An equilibrium of isomers of 1 and 2 has been observed in solution by ¹H and ¹⁹F NMR. The ¹⁹F NMR spectra of 1–3 are discussed in detail.     

Inhibition of Inducible Nitric Oxide Synthase Prevents IL-1β-Induced Mitochondrial Dysfunction in Human Chondrocytes

Interleukin (IL)-1β is an important pro-inflammatory cytokine in the progression of osteoarthritis (OA), which impairs mitochondrial function and induces the production of nitric oxide (NO) in chondrocytes. The aim was to investigate if blockade of NO production prevents IL-1β-induced mitochondrial dysfunction in chondrocytes and whether cAMP and AMP-activated protein kinase (AMPK) affects NO production and mitochondrial function. Isolated human OA chondrocytes were stimulated with IL-1β in combination with/without forskolin, L-NIL, AMPK activator or inhibitor. The release of NO, IL-6, PGE₂, MMP3, and the expression of iNOS were measured by ELISA or Western blot. Parameters of mitochondrial respiration were measured using a seahorse analyzer. IL-1β significantly induced NO release and mitochondrial dysfunction. Inhibition of iNOS by L-NIL prevented IL-1β-induced NO release and mitochondrial dysfunction but not IL-1β-induced release of IL-6, PGE₂, and MMP3. Enhancement of cAMP by forskolin reduced IL-1β-induced NO release and prevented IL-1β-induced mitochondrial impairment. Activation of AMPK increased IL-1β-induced NO production and the negative impact of IL-1β on mitochondrial respiration, whereas inhibition of AMPK had the opposite effects. NO is critically involved in the IL-1β-induced impairment of mitochondrial respiration in human OA chondrocytes. Increased intracellular cAMP or inhibition of AMPK prevented both IL-1β-induced NO release and mitochondrial dysfunction.     

FT-IR spectroscopic investigations of photochemical grafting of amphiphiles onto polyacrylonitrile surfaces

The photoreactive amphiphile p-(stearyl amido) benzoyl azide (SABAz) was synthesized and grafted onto surface of thin polyacrylonitrile (PAN) films by irradiation with UV light. Two different techniques were applied, namely, Langmuir–Blodgett (LB) deposition and casting from solution. A high degree of order and a hydrophobic surface were established by reflection-absorption FT-IR spectroscopy (RA-IR) and contact angle measurements. The stability against treatment with water, tetrahydrofuran, and chloroform was tested. A considerable amount of amphiphilic molecules remains on the surface also after treatment with chloroform. RA-IR spectra taken from photomodified PAN films prepared by both techniques are almost identical after chloroform treatment, indicating a similar coupling mechanism. © 1995 John Wiley & Sons, Inc.     

Adsorption and catalytic reactions of NO and NH3 on activated carbon

In industrial processes, the reduction of nitrogen oxides by ammonia on activated carbons is carried out at temperatures between 90 and 190 °C. Adsorption of NO and NH₃ on the catalyst was investigated separately. Reactions models for NO-reduction by carbon and ammonia were derived from experiments carried out in an integral reactor. In each case, the formation of an adsorbed (NO₂)-complex is an important step. The kinetics of both reactions was described by modified Langmuir-Hinshelwood equations.