Preprocessing Strategies for Sparse Infrared Spectroscopy: A Case Study on Cartilage Diagnostics

The aim of the study was to optimize preprocessing of sparse infrared spectral data. The sparse data were obtained by reducing broadband Fourier transform infrared attenuated total reflectance spectra of bovine and human cartilage, as well as of simulated spectral data, comprising several thousand spectral variables into datasets comprising only seven spectral variables. Different preprocessing approaches were compared, including simple baseline correction and normalization procedures, and model-based preprocessing, such as multiplicative signal correction (MSC). The optimal preprocessing was selected based on the quality of classification models established by partial least squares discriminant analysis for discriminating healthy and damaged cartilage samples. The best results for the sparse data were obtained by preprocessing using a baseline offset correction at 1800 cm−1, followed by peak normalization at 850 cm−1 and preprocessing by MSC.publishedVersio

Surface Physicochemical Properties At The Micro And Nano Length Scales: Role On Bacterial Adhesion And Xylella Fastidiosa Biofilm Development.

The phytopathogen Xylella fastidiosa grows as a biofilm causing vascular occlusion and consequently nutrient and water stress in different plant hosts by adhesion on xylem vessel surfaces composed of cellulose, hemicellulose, pectin and proteins. Understanding the factors which influence bacterial adhesion and biofilm development is a key issue in identifying mechanisms for preventing biofilm formation in infected plants. In this study, we show that X. fastidiosa biofilm development and architecture correlate well with physicochemical surface properties after interaction with the culture medium. Different biotic and abiotic substrates such as silicon (Si) and derivatized cellulose films were studied. Both biofilms and substrates were characterized at the micro- and nanoscale, which corresponds to the actual bacterial cell and membrane/ protein length scales, respectively. Our experimental results clearly indicate that the presence of surfaces with different chemical composition affect X. fastidiosa behavior from the point of view of gene expression and adhesion functionality. Bacterial adhesion is facilitated on more hydrophilic surfaces with higher surface potentials; XadA1 adhesin reveals different strengths of interaction on these surfaces. Nonetheless, despite different architectural biofilm geometries and rates of development, the colonization process occurs on all investigated surfaces. Our results univocally support the hypothesis that different adhesion mechanisms are active along the biofilm life cycle representing an adaptation mechanism for variations on the specific xylem vessel composition, which the bacterium encounters within the infected plant.8e7524

Sol−gel processing of water‐soluble carbon nitride enables high‐performance photoanodes **

In spite of the enormous promise that polymeric carbon nitride (PCN) materials hold for various applications, the fabrication of high‐quality, binder‐free PCN films and electrodes has been a largely elusive goal to date. Here, we tackle this challenge by devising, for the first time, a water‐based sol−gel approach that enables facile preparation of thin films based on poly(heptazine imide) (PHI), a polymer belonging to the PCN family. The sol−gel process capitalizes on the use of a water‐soluble PHI precursor that allows formation of a non‐covalent hydrogel. The hydrogel can be deposited on conductive substrates, resulting in formation of mechanically stable polymeric thin layers. The resulting photoanodes exhibit unprecedented photoelectrochemical (PEC) performance in alcohol reforming and highly selective (∼100 %) conversions with very high photocurrents (>0.25 mA cm −2 under 2 sun) down to <0 V vs. RHE. This enables even effective PEC operation under zero‐bias conditions and represents the very first example of a ‘soft matter’‐based PEC system capable of bias‐free photoreforming. The robust binder‐free films derived from sol−gel processing of water‐soluble PCN thus constitute a new paradigm for high‐performance ‘soft matter’ photoelectrocatalytic systems and pave the way for further applications in which high‐quality PCN films are required.Completely unbiased : Robust binder‐free films derived from sol−gel processing of a water‐soluble polymeric carbon nitride precursor exhibit unprecedented performance in photoelectrocatalytic reforming of alcohols, including effective operation under bias‐free conditions

Boosting Efficiency in Light‐Driven Water Splitting by Dynamic Irradiation through Synchronizing Reaction and Transport Processes **

Abstract This work elaborates the effect of dynamic irradiation on light‐driven molecular water oxidation to counteract deactivation. It highlights the importance of overall reaction engineering to overcome limiting factors in artificial photosynthesis reactions. Systematic investigation of a homogeneous three‐component ruthenium‐based water oxidation system revealed significant potential to enhance the overall catalytic efficiency by synchronizing the timescales of photoreaction and mass transport in a capillary flow reactor. The overall activity could be improved by a factor of more than 10 with respect to the turnover number and a factor of 31 referring to the external energy efficiency by controlling the local availability of photons. Detailed insights into the mechanism of light driven water oxidation could be obtained using complementary methods of investigation like Raman, IR, and UV/Vis/emission spectroscopy, unraveling the importance of avoiding high concentrations of excited photosensitizers.Water splitting : Dynamic irradiation enables a significant increase in catalytic performance of a homogeneous three‐component system for light‐driven water oxidation. Lower irradiation intensities and higher flowrates in a flow‐through reactor minimize photosensitizer degradation and thus improve catalyst lifetime, yield, and overall efficiency of a catalytic system for artificial photosynthesis. imag

Chemical microsystem based on vertical integration of sensor array and CMOS circuit

Issued as final reportNational Science Foundation (U.S

From Systems Biology to Systems Analytics: Seeing More by Looking at Less

Boris Mizaikoff of the School of Chemistry and Biochemistry presented a lecture on Tuesday, October 9, 2007, 11 am in Room 1116W of the Klaus Advanced Computing Building on the Georgia Tech CampusRuntime: 46:35 minutesSystematic analysis of interactions between molecules and biological entities requires the development and application of experimental tools and analytical methods to quantitatively measure and image molecular events, molecular pathways, and molecular signals at the level of individual cells, ensembles of small biological entities and entire organisms with the required molecular selectivity, sensitivity, and temporal/spatial resolution. While it is evident that current analytical techniques are frequently limited to averaged measurements or ex-situ analysis, the analytical challenges for in-situ multi-parametric characterization of living biological entities such as cells, microbes, bacteria or ensembles thereof remain significant. Hence, in analogy and complementary to Systems Biology concerned with deciphering complex molecular processes and their relation to biological functionalities, we view Systems Analytics as the toolbox enabling the quantitative determination of multiple molecular parameters to elucidate these interactions and relations. From the analytic chemistry point of view, we may describe individual cells as a measurement compartment with spatial/volume dimensions in the μm-nm/μL-nL range, and quantitative molecular dimensions in the mM-nM domain. The spatial dimensionality of molecular events within or at cellular compartments (e.g. vesicular processes) or at the cell surface (e.g. exo-or endocytosis) along with the magnitude of the local species concentration determine the need for quantitative analytical measurements at the micro- and nanoscale. We will discuss the diversity of measurement challenges at these compartments, which include the small dimensions of the involved samples and volumes, the complex and frequently changing background matrix, the sensitivity and/or discriminatory power of in-situ analytical techniques, and their temporal and/or spatial resolution to quantitatively monitor dynamic processes associated with cellular functions. In turn, individual optical/spectroscopic, electrochemical, and surface sensitive analytical techniques have already demonstrated their potential at the macro- and microscopic level, i.e. identifying which molecular species are present, their concentration, their location, and — ideally - the kinetics, dynamics of the involved molecular processes. In contrast to approaches utilizing individual analytical techniques, the development of generic multifunctional analytical platforms orchestrates a suite of complementary measurement techniques to cooperatively investigate complex biological systems, complemented by the development of (bio)sensing chemistries, synthetic molecular receptors, multivariate evaluation techniques, and micro/nanofabrication for functional system miniaturization. Thereby, we capitalize on the benefits of several analytical techniques addressing the conformational, electrochemical, and spectroscopic properties of the sample leading toward simultaneous rather than the classical sequential information acquisition process, aiming at maximizing the synchronicity between multiple methods in the temporal and spatial domain

Towards on-chip mid-infrared sensors

This Feature highlights recent advances on mid-infrared thin-film waveguide technology and on-chip photonics facilitating next-generation label-free chem/bio sensor and assay platforms. Complemented by more recent advancements toward on-chip semiconductor waveguides, it is anticipated that label-free integrated mid-infrared sensing schemes will readily complement existing chem/bio sensor technologies in applications ranging from process monitoring and environmental analysis to biomedical diagnostics and point-of-care device

RobustATR: Substrate-Integrated Hollow Waveguide Coupled Infrared Attenuated Total Reflectance Sensors

Small and compact mid-infrared devices are of increasing importance, as there are several applications demanding on-site and real-time measurements in harsh real-world scenarios. The RobustATR, an innovative infrared attenuated total reflectance (IR-ATR) accessory, has been developed and tested with exemplary analytes integrating a single-wavelength Fabry–Pérot quantum cascade laser as light source for testing the feasibility of a potentially miniaturized overall sensor design. Successful direct coupling of the laser radiation via substrate-integrated hollow waveguide (iHWG) coupling elements to the sensor interface could be shown, whereby exemplary analytes of environmental and medical relevance were tested, revealing the future potential for real-world applications