Plasmonic waveguides are promising in many applications because of their subwavelength field confinement, which can strongly enhance light‐matter interactions. Nevertheless, how to efficiently evaluate their Kerr nonlinear performance is still an open question because of the presence of relatively large linear losses. Here a simple and versatile figure of merit (FOM) is proposed for Kerr nonlinear waveguides with linear losses. To derive the FOM, a generalized full‐vectorial nonlinear Schrödinger equation governing nonlinear pulse propagation in a lossy waveguide is developed, and an approximate analytic solution of the degenerate four wave mixing conversion efficiency is derived and validated. The effectiveness of the FOM is verified with an all‐plasmonic and a hybrid‐plasmonic waveguide configuration. Rigorous results show that the optimal waveguide length for the highest conversion efficiency is ln 3 times the attenuation length. At this length, the upper limits of the conversion efficiency and the nonlinear phase shift are determined by the FOM. These results provide fundamental theory and useful guidance in exploring plasmonic waveguides for nonlinear optical applications.
In Europe, the mean incidence of urinary tract infections in intensive care units is 1.1 per 1000 patient‐days. Of these cases, catheter‐associated urinary tract infections (CAUTI) account for 98%. In total, CAUTI in hospitals is estimated to give additional health‐care costs of £1–2.5 billion in the United Kingdom alone. This is in sharp contrast to the low cost of urinary catheters and emphasizes the need for innovative products that reduce the incidence rate of CAUTI. Ureteral stents and other urinary‐tract devices suffer similar problems. Antimicrobial strategies are being developed, however, the evaluation of their efficacy is very challenging. This review aims to provide considerations and recommendations covering all relevant aspects of antimicrobial material testing, including surface characterization, biocompatibility, cytotoxicity, in vitro and in vivo tests, microbial strain selection, and hydrodynamic conditions, all in the perspective of complying to the complex pathology of device‐associated urinary tract infection. The recommendations should be on the basis of standard assays to be developed which would enable comparisons of results obtained in different research labs both in industry and in academia, as well as provide industry and academia with tools to assess the antimicrobial properties for urinary tract devices in a reliable way. 相似文献
The performance of zeolite-based catalyst extrudates can be largely influenced by the choice of binder material. To investigate these binder effects in zeolite-based catalyst extrudates in more detail, high spatiotemporal resolution techniques need to be further developed and employed. In this work, we present a new methodology to investigate binder effects in catalyst extrudates at different reaction pressures using operando UV-vis diffuse reflectance (DR) micro-spectroscopy coupled with on-line gas chromatography. We have studied mm-sized zeolite H-ZSM-5-containing extrudates with either Al2O3 or SiO2 binder material, during the transalkylation of toluene with 1,2,4-trimethylbenzene at 450 °C and at a pressure of either 1 or 5 bar. Using this technique, it was revealed that the binder material significantly influenced catalyst deactivation at different reaction pressures. By subsequent mapping of the cross sections of the cylindrical catalyst extrudates using UV-vis micro-spectroscopy, it was shown that the SiO2-bound extrudate formed poly-aromatic coke molecules homogeneously throughout the entire extrudate, whereas for the Al2O3-bound extrudate a coke ring formed that moved inwards with increasing reaction time. Notably, the developed methodology is not limited to the transalkylation reaction, and can also be used to gain more insight into binder effects during a variety of important catalytic reactions. 相似文献
It remains a challenge to precisely tailor the morphology of polymer monolayers to control charge transport. Herein, the effect of the dissolution temperature (Tdis) is investigated as a powerful strategy for morphology control. Low Tdis values cause extended polymer aggregation in solution and induce larger nanofibrils in a monolayer network with more pronounced π–π stacking. The field-effect mobility of the corresponding monolayer transistors is significantly enhanced by a factor of four compared to devices obtained from high Tdis with a value approaching 1 cm2 V−1 s−1. Besides that, the solution kinetics reveal a higher growth rate of aggregates at low Tdis, and filtration experiments further confirm that the dependence of the fibril width in monolayers on Tdis is consistent with the aggregate size in solution. The generalizability of the Tdis effect on polymer aggregation is demonstrated using three other conjugated polymer systems. These results open new avenues for the precise control of polymer aggregation for high-mobility monolayer transistors. 相似文献
A variety of para-substituted NCN-pincer palladium(II) and platinum(II) complexes [MX(NCN-Z)] (M=Pd(II), Pt(II); X=Cl, Br, I; NCN-Z=[2,6-(CH(2)NMe(2))(2)C(6)H(2)-4-Z](-); Z=NO(2), COOH, SO(3)H, PO(OEt)(2), PO(OH)(OEt), PO(OH)(2), CH(2)OH, SMe, NH(2)) were synthesised by routes involving substitution reactions, either prior to or, notably, after metalation of the ligand. The solubility of the pincer complexes is dominated by the nature of the para substituent Z, which renders several complexes water-soluble. The influence of the para substituent on the electronic properties of the metal centre was studied by (195)Pt NMR spectroscopy and DFT calculations. Both the (195)Pt chemical shift and the calculated natural population charge on platinum correlate linearly with the sigma(p) Hammett substituent constants, and thus the electronic properties of predesigned pincer complexes can be predicted. The sigma(p) value for the para-PtI group itself was determined to be -1.18 in methanol and -0.72 in water/methanol (1/1). Complexes substituted with protic functional groups (CH(2)OH, COOH) exist as dimers in the solid state due to intermolecular hydrogen-bonding interactions. 相似文献
A comprehensive method for the quantitative residue analysis of trace levels of 22 ß-lactam antibiotics, including penicillins, cephalosporins, and carbapenems, in poultry muscle by liquid chromatography in combination with tandem mass spectrometric detection is reported. The samples analyzed for ß-lactam residues are hydrolyzed using piperidine in order to improve compound stability and to include the total residue content of the cephalosporin ceftifour. The reaction procedure was optimized using a full experimental design. Following detailed isotope labeling, tandem mass spectrometry studies and exact mass measurements using high-resolution mass spectrometry reaction schemes could be proposed for all ß-lactams studied. The main reaction occurring is the hydrolysis of the ß-lactam ring under formation of the piperidine substituted amide. For some ß-lactams, multiple isobaric hydrolysis reaction products are obtained, in accordance with expectations, but this did not hamper quantitative analysis. The final method was fully validated as a quantitative confirmatory residue analysis method according to Commission Decision 2002/657/EC and showed satisfactory quantitative performance for all compounds with trueness between 80 and 110 % and within-laboratory reproducibility below 22 % at target level, except for biapenem. For biapenem, the method proved to be suitable for qualitative analysis only.
Figure
Graphical representation of the analysis of penicillins, cephalosporins and carbapenems using LC-MS/MS 相似文献
Atomic XAFS on [PtCl(NCN)-Z] pincer complexes shows it to be a sensitive probe for the determination of the electron density on the metal atom, similar yet complementary to NMR. 相似文献
Surface phenomena are an important contribution to the "chip effect", leading to higher yields and shorter reaction times, as demonstrated for the acid-catalysed esterification of 9-pyrenebutyric acid within a glass fabricated micro reactor. 相似文献
