Amplifiers and Lasers in PCF Configurations

In this paper we will present an overview of the use of photonic crystal fibers as fiber amplifiers. We will describe the basic concepts of optical amplification, and how to do numerical modelling of such components. We will then identify advantages and disadvantages of amplifiers based on PCF technology compared to conventional fibers, and then go into greater detail on some of these specific applications, such as low pump power amplifiers, and high-power double-clad amplifiers and lasers.     

Microelectromagnet for magnetic manipulation in lab-on-a-chip systems

We demonstrate a simple scheme for fabrication of microelectromagnets consisting of planar spiral coils semi-encapsulated in soft magnetic yokes using conventional microfabrication techniques. The microelectromagnets are suitable for applications operating at frequencies below 250 kHz. Conventional fabrication schemes for planar microelectromagnets typically rely on five mask steps. We allow the current to flow in the soft magnetic yoke and thereby two mask steps are eliminated. We have characterized the electromagnets electrically, the results agree well with theory, and the implications arising from current flowing in the magnetic yoke are discussed. We have integrated the microelectromagnets with microfluidic channels, and demonstrated separation of commercially available magnetic beads from a fluid in a microfluidic system, i.e. a lab-on-a-chip system.     

Trace enrichment and HPLC analysis of polycyclic aromatic hydrocarbons in environmental samples,using solid phase extraction in connection with UV/VIS diode-array and fluorescence detection

Summary Both the separation of polycyclic aromatic hydrocarbons (PAH's) on tailor made HPLC phases, and their chromatographic enrichment and quantitative determination are of great interest. Because of the generally low concentrations of PAH's in the environment, and the low limiting values in German legislation for drinking water, methods for selective enrichment and sensitive detection are indispensable. On account of their relatively high amounts in soil, the determination of PAH's is valuable for the assessment of the potential danger to ground water by waste materials. These requirements can be fulfilled by used of solid phase extraction on enrichment columns, and fluorescence or UV/VIS diode array detection. For the detection of PAH's in the picogram range, the wavelengths for excitation and emission were time programmed over the chromatogram. With this feature, it is possible to detect all the individual compounds at the highest sensitivity, over the entire analysis.     

Configuration and E/Z interconversion mechanism of O(S)-allyl-S(O)-methyl-N-(acridin-9-yl) iminothiocarbonate

The configuration and dynamic behavior of O-allyl-S-methyl-N-(acridin-9-yl)iminothiocarbonate (1) and its S-allyl-O-methyl regioisomer (2) were studied using quantum chemical calculations and by applying a novel graphical method to scatter maps obtained from MD simulations for evaluation of an NOE-weighted internuclear distance (r(NOE)). Energy calculations indicated that the Z configuration was predominant for each compound and, further, this was supported both by the calculated chemical shifts and the r(NOE). Both N-inversion- and rotation-type transition-state structures were also calculated for the E/Z isomerization process, the results indicating that the preferred interconversion mechanism for 1 is N-inversion, but contrastingly, interconversion via rotation is equally as probable as N-inversion for 2. This supports the notion that one or the other or both pathways can be active and each system needs to be assessed on a case-by-case basis.     

Regiospecific synthesis,structure and electron ionization mass spectra of 1,3‐thiazolidin‐4‐ones containing the acridine skeleton

The synthesis of regioisomeric 3‐alkyl(aryl)‐2‐(acridin‐9′‐yl)imino‐1,3‐thiazolidin‐4‐ones ( 8b‐i ) and 2‐alkyl(aryl)imino‐3‐(acridin‐9′‐yl)‐1,3‐thiazolidin‐4‐ones ( 11a‐i ) was performed by the reaction of 3‐(acridin‐9‐yl)‐1‐alkyl(aryl)thioureas 5a‐i with methyl bromoacetate and bromoacetyl bromide, respectively, via the corresponding isothiourea hydrobromides with excellent regioselectivity. The structure, NMR spectra and mass spectrometric behavior of the resulting compounds are discussed.     

Iron(II)‐ and Cobalt(II) Complexes with Tridentate Bis(imino)pyridine Nitrogen Ligands Bearing Chiral Bulky Aliphatic and Aromatic Substituents: Crystal Structure of [CoCl2{2, 6‐bis[R‐(+)‐(bornylimino)methyl]pyridine}]

Iron(II) and cobalt(II) complexes ( 7 ‐ 15 ) based on new aldimine 2, 6‐bis[(imino)methyl]pyridine ( 1 , 2 , 4 , 6 ) and ketimine (2, 6‐bis[(imino)ethyl]pyridine ( 3 , 5 ) ligands with bulky chiral aliphatic or aromatic terminal groups have been prepared and characterized by ¹H NMR, ¹³C NMR, IR‐, mass spectroscopy (EI), and elemental analysis. The complex [CoCl₂(BBoMP)]·¹/₂ CHCl₃ ( 13 ) (BBoMP: 2, 6‐bis{(R‐(+)‐(bornylimino)‐methyl}pyridine) crystallizes in monoclinic space group P2₁ with cell dimensions: a = 7.6603(11) Å, b = 28.3153(14) Å, c = 13.537(2) Å, V = 2908.1(6) ų, Z = 4. The coordination sphere around Co is distorted trigonal bipyramidal.