Trypan Blue Dye Enters Viable Cells Incubated with the Pore-Forming Toxin HlyII of Bacillus cereus

Trypan blue is a dye that has been widely used for selective staining of dead tissues or cells. Here, we show that the pore-forming toxin HlyII of Bacillus cereus allows trypan blue staining of macrophage cells, despite the cells remaining viable and metabolically active. These findings suggest that the dye enters viable cells through the pores. To our knowledge, this is the first demonstration that trypan blue may enter viable cells. Consequently, the use of trypan blue staining as a marker of vital status should be interpreted with caution. The blue coloration does not necessarily indicate cell lysis, but may rather indicate pore formation in the cell membranes and more generally increased membrane permeability

Ultrafast nano-focusing with full optical waveform control

The spatial confinement and temporal control of an optical excitation on nanometer length scales and femtosecond time scales has been a long-standing challenge in optics. It would provide spectroscopic access to the elementary optical excitations in matter on their natural length and time scales and enable applications from ultrafast nano-opto-electronics to single molecule quantum coherent control. Previous approaches have largely focused on using surface plasmon polariton (SPP) resonant nanostructures or SPP waveguides to generate nanometer localized excitations. However, these implementations generally suffer from mode mismatch between the far-field propagating light and the near-field confinement. In addition, the spatial localization in itself may depend on the spectral phase and amplitude of the driving laser pulse thus limiting the degrees of freedom available to independently control the nano-optical waveform. Here we utilize femtosecond broadband SPP coupling, by laterally chirped fan gratings, onto the shaft of a monolithic noble metal tip, leading to adiabatic SPP compression and localization at the tip apex. In combination with spectral pulse shaping with feedback on the intrinsic nonlinear response of the tip apex, we demonstrate the continuous micro- to nano-scale self-similar mode matched transformation of the propagating femtosecond SPP field into a 20 nm spatially and 16 fs temporally confined light pulse at the tip apex. Furthermore, with the essentially wavelength and phase independent 3D focusing mechanism we show the generation of arbitrary optical waveforms nanofocused at the tip. This unique femtosecond nano-torch with high nano-scale power delivery in free space and full spectral and temporal control opens the door for the extension of the powerful nonlinear and ultrafast vibrational and electronic spectroscopies to the nanoscale.Comment: Contains manuscript with 4 figures as well as supplementary material with 2 figure

Theoretical Analysis the Optical Properties of Multi-coupled Silver Nanoshell Particles

The surface plasmon resonances of silver nanoshell particles are studied by Green’s function. The nanoshell system of plasmon resonances results from the coupling of the inner and outer shell surface plasmon. The shift of the nanoshell plasmon resonances wavelength is plotted against with different dielectric environments, several different dielectric cores, the ratio of the inner and outer radius, and also its assemblies. The results show that a red- and blue-shifted localized surface plasmon can be tuned over an extended wavelength range by varying dielectric environments, the dielectric constants and the radius of nanoshell core respectively. In addition, the separation distances, the distribution of electrical field intensity, the incident directions and its polarizations are also investigated. The study is useful to broaden the application scopes of Raman spectroscopy and nano-optics

Digital Infrastructures for Monitoring Circular Economy Investments by Financial Institutions and Government: A Research Agenda

Circular Economy (CE) and sustainability are getting high on the political agenda of governments on the global level. Businesses and supply chains are at the heart of that transition, and need to make big steps in the coming years for making the transition from a linear model of make-use-dispose towards a circular model. For this transition, financing plays a key role. Financial institutions operate in a highly regulated environment. In this context, we see two particular, yet complementary, areas where digital infrastructures can be of value to support this transition. They can (1) help the financial institutions gather data about supply chain operations and address the performance of financial instruments used for the green and circular transition (i.e. bottom-up, micro view); and (2) help regulators monitor the activities of financial institutions to ensure that provided financing is indeed used to stimulate circular supply chains (i.e. top-down, macro view). In this paper, we explore the scene for digital infrastructure deployment for CE monitoring when it comes to CE funding, and propose a framework and a research agenda on the topic

An ontological approach for eliciting and understanding needs in e-services

Abstract. The lack of a good understanding of customer needs within eservice initiatives caused severe financial losses in the Norwegian energy sector, resulting in the failure of e-service initiatives offering packages of independent services. One of the causes was a poor elicitation and understanding of the e-services at hand. In this paper, we propose an ontologically founded approach (1) to describe customer needs, and the necessary e-services that satisfy such needs, and (2) to bundle elementary e-services into needs-satisfying e-service bundles. The ontology as well as the associated reasoning mechanisms are codified in RDFS to enable software support for need elicitation and service bundling. A case study from the Norwegian energy sector is used to demonstrate how we put our theory into practice

Conceptualizing a bottom-up approach to service bundling

Offering service bundles to the market is a promising option for service providers to strengthen their competitive advantages, cope with dynamic market conditions and deal with heterogeneous consumer demand. Although the expected positive effects of bundling strategies and pricing considerations for bundles are covered well by the available literature, limited guidance can be found regarding the identification of potential bundle candidates and the actual process of bundling. The contribution of this paper is the positioning of bundling based on insights from both business and computer science and the proposition of a structured bundling method, which guides organizations with the composition of bundles in practice