Supercontinuum Absorption Spectroscopy for Combustion Diagnostics

During recent years, sensors and diagnostic systems have seen an increase in demand, due to stricter legislative regulations for certification, as well as industry trends, such as Internet of Things and Industry 4.0. In addition, recent scientific discoveries (for example gravitational wave detection) are the result of international collaborations in the field of sensors and diagnostics. The ability to measure process-relevant parameters, preferably in situ and disturbance-free, is essential for improving performance of various systems, from chemical plants to internal combustion engines and energy power plants. Only with precise knowledge of the parameters of these processes, an improvement in efficiency and a reduction of pollutant emissions is achievable. Given the process optimizations in the last decade, the conditions under which a diagnostic system has to obtain valid measurements have significantly harshened. Most of the requirements can only be fulfilled with multi-scalar and multi-species measurements. To obtain such measurements, an optical diagnostic system is often unavoidable, especially for in situ measurements. Given its robustness and versatility, absorption spectroscopy offers great possibilities for such measurements. With the recent arrival of Supercontinuum Laser Light Source (SCLs), which offer broad spectral coverage in pulsed form, the concept of Supercontinuum Laser Broadband Absorption Spectroscopy (SCLAS) was developed, relying on a dispersion in time to record optical spectra. Given the broad spectral coverage, it is possible to derive multiple scalars including species concentrations, pressure and temperature purely optical. Furthermore, such broad coverage is essential for measurements in high-pressure environments (i.e. within the cylinder of an internal combustion engine). Based on an extensive discussion of the underlying effects and processes, necessary spectroscopic models and algorithms were developed to process the obtained measurements. Based on these models, several test cases for SCLAS were investigated, including static tests to quantify accuracy and uncertainty, as well as steady-state laminar flames. Based on the knowledge of these experiments, SCLAS was transferred to transient systems including high-pressure cells and was applied for in-cylinder measurements at a transparent engine test bed. In addition, based on the results of the validation and application tests, new spectroscopic models were developed to fully utilize the potential of SCLs in general and SCLAS in particular. These new models were evaluated against standard practices and found to be an improvement with regards to complexity and speed of data-processing. Furthermore, these models, as opposed to standard gas absorption spectroscopy models, allow for modelling of liquids as well as complex non-discrete absorbing species, such as propane and AdBlue (DEF). Overall, the diagnostic technique SCLAS was proven in comparison to established techniques, while advanced approaches to measure in situ in high-pressure high-temperature processes were developed and tested

Insulin gene regulation and islet development as studied in genetically modified tumors and transgenic laboratory animals

The pancreatic islet of Langerhans is composed of four highly distinct cell types specialized to mass produce a particular hormone. Insulin is thus the main product released from the islet B—cell in response to elevated glucose.The four cell types maturate during fetal development. Pluripotent rat islet tumors can to a certain degree undergo similar maturation processes when passaged in vivo. Such a model has been used to study the B—cell specific process of insulin gene activation. Transgenic mice have been instrumental in defining the functional regulatory elements involved in restricting the insulin gene activity to the pancreatic B-cell. The tissue-specific enhancer/promoter has thus been identified and used in combination with a series of other genes which in transgenic mice targets expression of the gene in question selectively to the B-cell. Important transacting factors have been identified and cloned which are in part responsible for mediating tissue specific insulin gene expression. One such factor when "knocked-out" results in a phenotype lacking the entire pancreas. Future developments in targeting "knockout" of genes to particular cell types will help dissecting out the multiple functions of such regulatory transacting factors

Data analysis and uncertainty estimation in supercontinuum laser absorption spectroscopy

A set of algorithms is presented that facilitates the evaluation of super continuum laser absorption spectroscopy (SCLAS) measurements with respect to temperature, pressure and species concentration without the need for simultaneous background intensity measurements. For this purpose a non-linear model fitting approach is employed. A detailed discussion of the influences on the instrument function of the spectrometer and a method for the in-situ determination of the instrument function without additional hardware are given. The evaluation procedure is supplemented by a detailed measurement precision assessment by applying an error propagation through the non-linear model fitting approach. While the algorithms are tailored to SCLAS, they can be transferred to other spectroscopic methods, that similarly require an instrument function. The presented methods are validated using gas cell measurements of methane in the near infrared region at pressures up to 8.7 bar

Autoimmunity in CD73/Ecto-5′-Nucleotidase Deficient Mice Induces Renal Injury

Extracellular adenosine formed by 5′-ectonucleotidase (CD73) is involved in tubulo-glomerular feedback in the kidney but is also known to be an important immune modulator. Since CD73−/−mutant mice exhibit a vascular proinflammatory phenotype, we asked whether long term lack of CD73 causes inflammation related kidney pathologies. CD73−/−mice (13 weeks old) showed significantly increased low molecule proteinuria compared to C57BL6 wild type controls (4.8≥0.52 vs. 2.9±0.54 mg/24 h, p<0.03). Total proteinuria increased to 5.97±0.78 vs. 2.55±0.35 mg/24 h at 30 weeks (p<0.01) whereas creatinine clearance decreased (0.161±0.02 vs. 0.224±0.02 ml/min). We observed autoimmune inflammation in CD73−/−mice with glomerulitis and peritubular capillaritis, showing glomerular deposition of IgG and C3 and enhanced presence of CD11b, CD8, CD25 as well as GR-1-positive cells in the interstitium. Vascular inflammation was associated with enhanced serum levels of the cytokines IL-18 and TNF-α as well as VEGF and the chemokine MIP-2 (CXCL-2) in CD73−/−mice, whereas chemokines and cytokines in the kidney tissue were unaltered or reduced. In CD73−/−mice glomeruli, we found a reduced number of podocytes and endothelial fenestrations, increased capillaries per glomeruli, endotheliosis and enhanced tubular fibrosis. Our results show that adult CD73−/−mice exhibit spontaneous proteinuria and renal functional deterioration even without exogenous stress factors. We have identified an autoimmune inflammatory phenotype comprising the glomerular endothelium, leading to glomeruli inflammation and injury and to a cellular infiltrate of the renal interstitium. Thus, long term lack of CD73 reduced renal function and is associated with autoimmune inflammation

Supercontinuum Absorption Spectroscopy for Combustion Diagnostics

During recent years, sensors and diagnostic systems have seen an increase in demand, due to stricter legislative regulations for certification, as well as industry trends, such as Internet of Things and Industry 4.0. In addition, recent scientific discoveries (for example gravitational wave detection) are the result of international collaborations in the field of sensors and diagnostics. The ability to measure process-relevant parameters, preferably in situ and disturbance-free, is essential for improving performance of various systems, from chemical plants to internal combustion engines and energy power plants. Only with precise knowledge of the parameters of these processes, an improvement in efficiency and a reduction of pollutant emissions is achievable. Given the process optimizations in the last decade, the conditions under which a diagnostic system has to obtain valid measurements have significantly harshened. Most of the requirements can only be fulfilled with multi-scalar and multi-species measurements. To obtain such measurements, an optical diagnostic system is often unavoidable, especially for in situ measurements. Given its robustness and versatility, absorption spectroscopy offers great possibilities for such measurements. With the recent arrival of Supercontinuum Laser Light Source (SCLs), which offer broad spectral coverage in pulsed form, the concept of Supercontinuum Laser Broadband Absorption Spectroscopy (SCLAS) was developed, relying on a dispersion in time to record optical spectra. Given the broad spectral coverage, it is possible to derive multiple scalars including species concentrations, pressure and temperature purely optical. Furthermore, such broad coverage is essential for measurements in high-pressure environments (i.e. within the cylinder of an internal combustion engine). Based on an extensive discussion of the underlying effects and processes, necessary spectroscopic models and algorithms were developed to process the obtained measurements. Based on these models, several test cases for SCLAS were investigated, including static tests to quantify accuracy and uncertainty, as well as steady-state laminar flames. Based on the knowledge of these experiments, SCLAS was transferred to transient systems including high-pressure cells and was applied for in-cylinder measurements at a transparent engine test bed. In addition, based on the results of the validation and application tests, new spectroscopic models were developed to fully utilize the potential of SCLs in general and SCLAS in particular. These new models were evaluated against standard practices and found to be an improvement with regards to complexity and speed of data-processing. Furthermore, these models, as opposed to standard gas absorption spectroscopy models, allow for modelling of liquids as well as complex non-discrete absorbing species, such as propane and AdBlue (DEF). Overall, the diagnostic technique SCLAS was proven in comparison to established techniques, while advanced approaches to measure in situ in high-pressure high-temperature processes were developed and tested

Islet expression of Rhombotin and Isl-1 suggests cell type specific exposure of LIM-domain epitopes

The homeodomain protein Isl-1 and the proto-oncogene Rhombotin (a LIM-only protein), share a double zinc-binding LIM domain and have both been implicated in neural and possibly endocrine development. Isl-1 is expressed in all endocrine cell-types of the islet of Langerhans while Rhombotin mRNA expression was reported in rat insulinoma cells. We have cloned and sequenced Rhombotin cDNA from rat insulinoma (99.4% identical to human and mouse sequences) and demonstrate that it is expressed in normal islets, intestinal tissue, and testis, in addition to the brain; but absent in all other organs tested. Rhombotin mRNA is expressed in phenotypically distinct islet tumours (alpha-, beta, and delta-tumours) at levels comparable to that of normal islets. Antisera raised against two distinct epitopes contained within a short synthetic peptide representing part of the N-terminal LIM domain of Rhombotin surprisingly stain alpha- and delta-cells, respectively, on sections of rat pancreas. Rhombotin is undetectable by immunocytochemistry using LIM-domain antisera on intact monolayer islet tumor cells or transfected fibroblasts while readily detectable when equipped with a FLAG epitope, as detected with FLAG antiserum. In contrast, recombinant FLAG-Rhombotin is efficiently recognised by Western blotting or immunoprecipitation with all LIM-specific antisera. Almost identical results were obtained with LIM-specific versus homeodomain/C-terminal Isl-1 antisera staining alpha-cell cytoplasm or all islet nuclei, respectively. We conclude that Rhombotin in addition to Isl-1 is expressed in the islet of Langerhans and propose that the differential staining patterns obtained with antisera towards the LIM domains versus flanking epitopes of both proteins reflect (1) cell-specific protein-protein interactions of these domains or alternatively, (2) islet cell type specific expression of novel homologous LIM domain proteins