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To meet the demands of the chemical and pharmaceutical process industry for a combination of high measurement accuracy, product selectivity, and low cost of ownership, the existing measurement and evaluation methods have to be further developed. This paper demonstrates the attempt to combine future Raman photometers with promising evaluation methods. As part of the investigations presented here, a new and easy-to-use evaluation method based on a self-learning algorithm is presented. This method can be applied to various measurement methods and is carried out here using an example of a Raman spectrometer system and an alcohol-water mixture as demonstration fluid. The spectra’s chosen bands can be later transformed to low priced and even more robust Raman photometers. The evaluation method gives more precise results than the evaluation through classical methods like one primarily used in the software package Unscrambler. This technique increases the accuracy of detection and proves the concept of Raman process monitoring for determining concentrations. In the example of alcohol/water, the computation time is less, and it can be applied to continuous column monitoring.

This work presents a novel method for the non-invasive, in-line monitoring of mixing processes in microchannels using the Raman photometric technique. The measuring set-up distinguishes itself from other works in this field by utilizing recent state-of-the-art customized photon multiplier (CPM) detectors, bypassing the use of a spectrometer. This addresses the limiting factor of integration times by achieving measuring rates of 10 ms. The method was validated using the ternary system of toluene&ndash, water&ndash, acetone. The optical measuring system consists of two functional units: the coaxial Raman probe optimized for excitation at a laser wavelength of 532 nm and the photometric detector centered around the CPMs. The spot size of the focused laser is a defining factor of the spatial resolution of the set-up. The depth of focus is measured at approx. 85 &micro, m with a spot size of approx. 45 &micro, m, while still maintaining a relatively high numerical aperture of 0.42, the latter of which is also critical for coaxial detection of inelastically scattered photons. The working distance in this set-up is 20 mm. The microchannel is a T-junction mixer with a square cross section of 500 by 500 &micro, m, a hydraulic diameter of 500 &micro, m and 70 mm channel length. The extraction of acetone from toluene into water is tracked at an initial concentration of 25% as a function of flow rate and accordingly residence time. The investigated flow rates ranged from 0.1 mL/min to 0.006 mL/min. The residence times from the T-junction to the measuring point varies from 1.5 to 25 s. At 0.006 mL/min a constant acetone concentration of approx. 12.6% was measured, indicating that the mixing process reached the equilibrium of the system at approx. 12.5%. For prototype benchmarking, comparative measurements were carried out with a commercially available Raman spectrometer (RXN1, Kaiser Optical Systems, Ann Arbor, MI, USA). Count rates of the spectrophotometer surpassed those of the spectrometer by at least one order of magnitude at identical target concentrations and optical power output. The experimental data demonstrate the suitability and potential of the new measuring system to detect locally and time-resolved concentration profiles in moving fluids while avoiding external influence.

The industrial particle sensor market lacks simple, easy to use, low cost yet robust, safe and fast response solutions. Towards development of such a sensor, for in-line use in micro channels under continuous flow conditions, this work introduces static light scattering (SLS) determination of particle diameter using a laser with an emission power of less than 5 &micro, W together with sensitive detectors with detection times of 1 ms. The measurements for the feasibility studies are made in an angular range between 20&deg, and 160&deg, in 2&deg, increments. We focus on the range between 300 and 1000 nm, for applications in the production of paints, colors, pigments and crystallites. Due to the fast response time, reaction characteristics in microchannel designs for precipitation and crystallization processes can be studied. A novel method for particle diameter characterization is developed using the positions of maxima and minima and slope distribution. The novel algorithm to classify particle diameter is especially developed to be independent of dispersed phase concentration or concentration fluctuations like product flares or signal instability. Measurement signals are post processed and particle diameters are validated against Mie light scattering simulations. The design of a low cost instrument for industrial use is proposed.

The design of a desalination plant is most important if the desired product purity has to be as high as possible. This is also true for freeze crystallization plants. A correct solid-to-liquid ratio has to be ensured when pressing is used as a post-treatment. Thus, the dependence of the overall plant design on the achieved ice quality but also on different hydraulic and thermodynamic numbers is important. In this research, a scraped screw crystallizer plant is presented and examined for two different screw designs. Experiments with a low initial concentration, as for the usage to desalinate groundwater to gain it as process water, were conducted. Furthermore, solutions with high initial concentrations simulating seawater to produce potable water were used as another set of test solutions. The findings showed that neither of the screw designs is more favorable than the other, but it is important to have a plant design fitting the existing parameters on site.

This paper provides an overview of how molecule-sensitive, spatially-resolved technologies can be applied for monitoring and measuring in microchannels. The principles of elastic light scattering, fluorescence, near-infrared, mid-infrared, and Raman imaging, as well as combination techniques, are briefly presented, and their advantages and disadvantages are explained. With optical methods, images can be acquired both scanning and simultaneously as a complete image. Scanning technologies require more acquisition time, and fast moving processes are not easily observable. On the other hand, molecular selectivity is very high, especially in Raman and mid-infrared (MIR) scanning. For near-infrared (NIR) images, the entire measuring range can be simultaneously recorded with indium gallium arsenide (InGaAs) cameras. However, in this wavelength range, water is the dominant molecule, so it is sometimes necessary to use complex learning algorithms that increase the preparation effort before the actual measurement. These technologies excite molecular vibrations in a variety of ways, making these methods suitable for specific products. Besides measurements of the fluid composition, technologies for particle detection are of additional importance. With scattered light techniques and evaluation according to the Mie theory, particles in the range of 0.2–1 µm can be detected, and fast growth processes can be observed. Local multispectral measurements can also be carried out with fiber optic-coupled systems through small probe heads of approximately 1 mm diameter.

The development of sustainable trucks has drawn a lot of attention lately. However, the reduction of fuel consumption and emissions related to deep frozen food transports has not yet been satisfactorily considered. In this paper, a thermal Large Eddy Lattice Boltzmann Method (LES-LBM) is applied to investigate two concepts for optimized refrigerated vehicles: (a) the inclusion of vacuum insulation panels (VIP) in the refrigerated body’s walls and (b) the introduction of a latent heat storage (LHS) to exchange fuel-driven air conditioning (AC), both with conveniently worth while potential to decrease fuel consumption and related emissions. The present numerical method allows for an accurate and efficient transient conjugate heat transfer simulation including the spatial and temporal resolution of the temperature distribution inside the insulation walls and the cargo in addition to the turbulent surrounding air flow induced by the AC. The present concept of VIP inclusion is found capable of halving the required cooling energy. In addition, it effectively reduces the variations in the temperature of the chilled goods during cooling operation, which is an important measure of the quality of the refrigerated body. The reduced required cooling energy is further found to enable the AC system to be replaced by a LHS mounted near the top of the refrigerator body and an additional ventilation system of lower total capacity. A comparison between simulations with conventional AC and LHS is conducted concerning the temperature homogeneity of loaded deep frozen food products. It is shown that a slight flow around the refrigerated goods is necessary and the maximum downtime of the AC system is 8 min in case of combined PUR and VIP insulation and 11 min in case of an additional LHS.

Potable water production is an essential but energy intensive process and usually requires many chemicals. Furthermore, small-scale plants are not yet available because of the problems associated with downscaling the thermal evaporation or reverse osmosis processes. Freeze crystallization is an alternative, especially for the self-sufficiency of potable water in remote areas. The use of a crystallizer and a separate press in combination with a perforated pressing mold has shown that the desalination of saltwater can be achieved by pressing the ice only; no additional washing step is necessary. A pressing force of 37.4 kN (100 bar) and a holding time of 180 s were found to be sufficient. Therefore, these parameters were used to design a single-step plant, which also showed good results in the case of ion expulsion. Nonetheless, the variation in the test parameters showed their influence on crystal growth and crystal purity and demonstrated the need to find the optimal design parameters for future continuously operating systems.

This study presents a novel concept for a direct contact latent heat storage, which can be used for storing thermal energy from industrial waste heat or renewable energy systems. A storage medium, phase change material (PCM), and mineral oil heat transfer fluid (HTF) are placed in direct contact. The PCM and the oil are not miscible. The direct contact leads to an improved heat transfer and faster loading and unloading periods with a high storage density. Only affordable salt hydrates or mixtures of salt hydrates and additives are used as the PCM. For the scaling of the system, the heat transfer coefficient of the complex system must be known. A cylindrical channel inside the PCM is created, and the heat transfer coefficients between the oil and solid or melting PCM is investigated. Subsequently, the transmission in a real channel is described and discussed.

This paper presents an explosion-proof two-channel Raman photometer designed for chemical process monitoring in hazardous explosive atmospheres. Due to its design, alignment of components is simplified and economic in comparison to spectrometer systems. Raman spectrometers have the potential of becoming an increasingly important tool in process analysis technologies as part of molecular-specific concentration monitoring. However, in addition to the required laser power, which restricts use in potentially explosive atmospheres, the financial hurdle is also high. Within the scope of a proof of concept, it is shown that photometric measurements of Raman scattering are possible. The use of highly sensitive detectors allows the required excitation power to be reduced to levels compliant for operation in potentially explosive atmospheres. The addition of an embedded platform enables stable use as a self-sufficient sensor, since it carries out all calculations internally. Multi-pixel photon counters (MPPCs) with large detection areas of 1350 µm2 are implemented as detectors. As a result, the sensitivity of the sensor is strongly increased. This gain in sensitivity is primarily achieved through two characteristics: first, the operating principle “avalanche breakdown” to detect single photons is used; second, the size of the image projected onto the MPPC is much bigger than the pixel area in competing Raman-Spectrometers resulting in higher photon flux. This combination enables reduction of the required excitation power to levels compliant for operation in potentially explosive atmospheres. All presented experiments are performed with strongly attenuated laser power of 35 mW. These include the monitoring of the analytes ethanol and hydrogen peroxide as well as the reversible binding of CO2 to amine. Accordingly, the described embedded sensor is ideally suited as a process analytical technology (PAT) tool for applications in environments with limitations on power input.

Thermal energy storage is gaining importance within the framework of energy turnaround. It is required in many applications to supply heat at a constant temperature. Therefore, phase change materials (PCMs) are considered suitable storage media in these cases. In this study, a eutectic salt hydrate mixture with a phase change temperature of approximately 21 °C was used. An amount of 600 kg was divided into sealed impermeable bags and placed at different spots in a prefabricated wooden house. Temperature sensors were placed inside the PCM bags, inside the room, and in the outside air. Temperature data were collected over 10 months under real environmental conditions. Furthermore, the thermal contact between the PCM and the interior space was investigated. The design that comprises PCM installation into a wall with back-ventilation proved to have the highest heat transfer rate. In addition, a simulation model was developed and applied to some PCM assemblies in order to characterize the effect of larger amounts of PCMs on the thermal behavior over an entire year and to forecast the energy requirements of the system. The results indicated that salt hydrates are cost effective and have a significantly positive effect on the thermal behavior of prefabricated wooden houses.

The heat transfer between particles and walls has been topic of research for several decades. In most cases existing correlations were developed empirically for special conditions and applications like fluidized beds or rotary kilns. With a deeper fundamental understanding of the occurring heat transfer mechanisms both design of existing and development of innovative apparatuses, could be more straightforward since the mentioned existing correlations cannot be applied flawlessly to other conditions, due to specific simplifications and assumptions. The aim of this work is to investigate the fundamental heat transfer mechanisms between spherical particles rolling on a plate on the microscale with the lowest level of simplifications. For the identification of the dominating heat transfer mechanisms an approach with Computational Fluid Dynamics (CFD) simulations is chosen. The fundamental investigations are carried out using a basic geometry of a moving sphere on a plate. Due to the lack of a solver which is able to describe the system of a moving sphere on a plate, a new solver is developed in OpenFOAM ® . The solver is validated against an existing model as well as own experimental results. Simulations in the laminar flow region show good agreement. Analogically to literature the main transport resistance is identified in the gap between plate and sphere. The heat conduction through the gas layer between sphere and plate is identified as the dominating mechanism.

In this study, we present an efficient and innovative method to visualize absorption differences in the mid-infrared range with spatial resolution using laser technology. We focus on only two lasers with wavelengths between 3.4 μm and 3.6 μm and a spatial resolution of 20 μm and thus achieve a scanning speed up to 300 kS/s for fast image generation. In this article, we focus especially on the detection of C–H bands in this region of the absorption spectrum. Concealed structures are examined by calculating the measured structures with both wavelengths. In our results, we demonstrate exemplary measurements on 130-μm-thick polyvinyl chloride layers. In turn, these structures are suitable for further processing in rapid quantitative quality control.

Vacuum insulation panels are high-performance insulating materials with considerably better thermal properties than conventional thermal insulation. Unfortunately, their use is limited to applications where their high price does not matter. To extend the application range of vacuum insulation, the authors try to replace the high-priced core material fumed silica with the cheaper precipitated silica. For this purpose, five commercially available precipitated silica samples were tested for their suitability as core material for vacuum insulations. They were pre-pressed with 5 bar and 30 bar each. To compare their thermal performances, a guarded hot plate apparatus for measuring thermal conductivities under vacuum was developed. The pore size distributions of the samples were measured by mercury intrusion porosimetry and used to calculate the gas thermal conductivity as a function of the residual pressure. For this purpose, a correction factor for the measured pore size distribution is introduced. Additionally, the coupling effect between gaseous and solid thermal conductivity could be determined through comparison with measured data. A model is presented to predict the thermal conductivity curve, even of unknown silica samples, solely using mercury intrusion porosimetry data.

Multimodal imaging gains increasing popularity for biomedical applications. This article presents the design of a novel multimodal imaging system. The centerpiece is a light microscope operating in the incident and transmitted light mode. Additionally, Raman spectroscopy and VIS/NIR reflectance spectroscopy are adapted. The proof-of-concept is realized to distinguish between grey matter (GM) and white matter (WM) of normal mouse brain tissue. Besides Raman and VIS/NIR spectroscopy, the following optical microscopy techniques are applied in the incident light mode: brightfield, darkfield, and polarization microscopy. To complement the study, brightfield images of a hematoxylin and eosin (H&amp, E) stained cryosection in the transmitted light mode are recorded using the same imaging system. Data acquisition based on polarization microscopy and Raman spectroscopy gives the best results regarding the tissue differentiation of the unstained section. In addition to the discrimination of GM and WM, both modalities are suited to highlight differences in the density of myelinated axons. For Raman spectroscopy, this is achieved by calculating the sum of two intensity peak ratios (I2857 + I2888)/I2930 in the high-wavenumber region. For an optimum combination of the modalities, it is recommended to apply the molecule-specific but time-consuming Raman spectroscopy to smaller regions of interest, which have previously been identified by the microscopic modes.

Best practice energy efficiency goals (EU 2030 climate & energy framework) require substantial improvements in thermal insulation. Vacuum Insulation Panels (VIPs) offer considerable advantages over traditional insulation materials in terms of thermal insulation performance, with effective thermal conductivities between 0.004 and 0.008 W/(m · K) (Kalnaes and Jelle, 2014). Each application, however, has different requirements, and the influence of the VIPs’ microstructure on the insulation performance is not yet entirely understood. Thus, in this work, a methodology is presented to achieve a complete pathway from measured particle characteristics to the resulting macroscopic heat transfer. The authors use the primary particle size, primary pore size, aggregate diameter, shape and standard deviation, as well as overall packing porosity to define a mesoscopic procedural generation of nano-porous geometry. Moreover, the local pore size is evaluated in order to simulate pore scale heat transfer. A distinct advantage over similar methods is the holistic approach presented provides direct tuning and control over particle packing characteristics to study their influence on conduction and radiation independently. The proposed automated numerical approach is applied to study the effective thermal conductivity of silica samples directly from particle measurements, enabling rapid prototyping of packing materials for varied compositions, facilitating the production of application optimized VIP configurations. The simulation results are compared to measurement and literature values.

In process analytics, the applicability of Raman spectroscopy is restricted by high excitation intensities or the long integration times required. In this work, a novel Raman system was developed to minimize photon flux losses. It allows specific reduction of spectral resolution to enable the use of Raman spectroscopy for real-time analytics when strongly increased sensitivity is required. The performance potential of the optical setup was demonstrated in two exemplary applications: First, a fast exothermic reaction (Michael addition) was monitored with backscattering fiber optics under strongly attenuated laser power (7 mW). Second, high-speed scanning of a segmented multiphase flow (water/toluene) with submicroliter droplets was achieved by aligning the focus of a coaxial Raman probe with long focal length directly into a perfluoroalkoxy (PFA) capillary. With an acquisition rate of 333 Raman spectra per second, chemical information was obtained separately for both of the rapidly alternating phases. The experiment with reduced laser power demonstrates that the technique described in this paper is applicable in chemical production processes, especially in hazardous environments. Further potential uses can be envisioned in medical or biological applications with limited power input. The realization of high-speed measurements shows new possibilities for analysis of heterogeneous phase systems and of fast reactions or processes.

Die Bewegungsmuster von Bakterien wurden mit einem neuartigen bildanalytischen Messsystem untersucht. Durch die flexibel und getaktet einstellbare Schichtdicke der Durchflusskuvette ist es moglich, alle Mikroorganismen im Messfenster im Tiefenscharfebereich von 3 µm darzustellen. Die Probenahme, Datenerfassung und Auswertung erfolgt vollautomatisch. Eine automatische Analyse von Bewegungsmustern von Mikroorganismen ist damit erstmals in dieser Weise moglich. Die erhaltenen Daten erlauben Ruckschlusse auf die Vitalitat der Bakterien und konnen fur die Fermentationsoptimierung genutzt werden. The movement characteristics of flagellated microorganisms were investigated using a novel microscope-based online imaging tool for fermentation control. A flexible flow through cuvette run in a chopped mode was used. The cuvette allows observations of microorganisms in a depth of field of 3 µm. The whole process of sampling, image acquisition and analysis is fully automated. Besides the measurement of the velocity of flagellated microorganisms, in this study the ability of the system to measure characteristic movement patterns of the bacteria is described for the first time. This information allows further conclusions on the viability status of bacteria during fermentation processes and can be used for fermentation optimization.

The study presents a latent heat storage system consisting of a phase change material (PCM) and a heat transfer fluid (HTF), placed in direct contact, for storing thermal energy derived from renewable energy sources or industrial waste heat. It is important that the two media are immiscible for the function of such a storage system. In this study the PCM was an eutectic mixture of the two salt hydrates, magnesium nitrate hexahydrate and magnesium chloride hexahydrate and the HTF was a mineral oil. The direct contact leads to intensified heat transfer compared to that in the indirect contact heat storage systems. This intensified heat transfer results in short loading and unloading periods of the storage tank with a high heat exchange performance. Furthermore, a higher storage density is observed in comparison to the sensible storage systems, particularly when combined with low temperature differences between the charged and discharged storage systems. In our study, the heat transfer between liquid PCM and liquid HTF (rises drop-shaped in the PCM) is investigated. For this purpose, a storage tank has been built with only one HTF inlet opening in the bottom. For the time and space resolved data, the axial temperature profile, and the surface temperature of the rising droplet, as well as the PCM temperature, are measured with a specially developed, fast, near infrared sensitive, and fiber-coupled technique. These measurements made it possible to determine a local heat transfer coefficient between the PCM and HTF. With the chosen parameters and materials in this study a heat transfer coefficient of 1845 W/m² K was calculated.

The thermal accommodation coefficient is a measure for the quality of thermal energy exchange between gas molecules and a solid surface. It is an important parameter to describe heat flow in rarefied gases, for example, in aerospace or vacuum technology. As special application, it plays a decisive role for the thermal transport theory in silica filled vacuum insulation panels. So far, no values have been available for the material pairings of silica and various gases. For that reason, this paper presents thermal conductivity measurements under different gas-pressure conditions for precipitated and fumed silica in combination with the following gases: helium, air, argon, carbon dioxide (CO$_{2}$), sulfur dioxide (SO$_{2}$), krypton, and sulfur hexafluoride (SF$_{6}$). Additionally, a calculation method for determining thermal accommodation coefficients from the thermal conductivity curves in combination with the pore size distribution of silica determined by mercury intrusion porosimetry is introduced. The results are compared with existing models.

Due to reduced thermal conductivity, vacuum insulation panels (VIPs) provide significant thermal insulation performance. Our novel vacuum panels operate at reduced pressure and are filled with a powder of precipitated silicic acid to further hinder convection and provide static stability against atmospheric pressure. To obtain an in depth understanding of heat transfer mechanisms, their interactions and their dependencies inside VIPs, detailed microscale simulations are conducted. Particle characteristics for silica are used with a discrete element method (DEM) simulation, using open source software Yade-DEM, to generate a periodic compressed packing of precipitated silicic acid particles. This aggregate packing is then imported into OpenLB (openlb.net) as a fully resolved geometry, and used to study the effects on heat transfer at the microscale. A three dimensional Lattice Boltzmann method (LBM) for conjugated heat transfer is implemented with open source software OpenLB, which is extended to include radiative heat transport. The infrared intensity distribution is solved and coupled with the temperature through the emissivity, absorption and scattering of the studied media using the radiative transfer equation by means of LBM. This new holistic approach provides a distinct advantage over similar porous media approaches by providing direct control and tuning of particle packing characteristics such as aggregate size, shape and pore size distributions and studying their influence directly on conduction and radiation independently. Our aim is to generate one holistic tool which can be used to generate silica geometry and then simulate automatically the thermal conductivity through the generated geometry.

Es wird ein neues Messsystem vorgestellt, das speziell fur die Inline-Bestimmung von Partikelgrosenverteilungen in senkrechten Rohren konzipiert ist. Im Gegensatz zu bisherigen Messmethoden wurde das Gerat ausschlieslich fur die Prozesskontrolle entwickelt. Primarziel ist die schnelle Anzeige von Prozessabweichungen in der Industrie. Die Untersuchungen wurden an Produkten nach Klassierung durch eine Freischwinger-Siebmaschine durchgefuhrt. In den hier dargestellten Experimenten werden ein Siebriss und die damit einhergehende Storung der Partikelgrosenverteilung realitatsnah simuliert. A new measuring system is introduced, which is designed specifically for the inline measurement of particle size distributions in vertical tubes. In contrast to previous methods of measurement, the device was designed exclusively for the process control. The primary goal is to provide the industry with a system that is able to quickly display critical process deviations. The investigations are based on products classified with a cantilever screen. In the presented experiments a screen crack and the resulting distortion of particle size distribution are simulated realistically.

Freeze desalination as a sustainable concept to produce potable water can be a useful and an additional method to overcome the water crisis, especially with ongoing global warming in focus. Therefore, a scraped surface crystallizer in combination with a post-treatment pressing cone has been built on a laboratory scale to investigate any dependencies of ice purity and throughput on operational conditions. Furthermore, a new designed screw conveyor and an additionally installed force sensor led to a better understanding of mass flow, mass fraction and ice purity. Changing the mean coolant temperature and rotational speed of the screw showed their influences on the ability to separate brine from ice and thus on the overall efficiency of the test plant. The influence of one parameter can be compensated by adjusting another, which leaves more flexibility for the operator of such a plant. Additionally, several Nusselt correlations were checked for suitability as helpful tools to design an upscale.

This paper presents a real-time capable graphics processing unit (GPU)-based ultrasound simulator suitable for medical education. The main focus of the simulator is to synthesize realistic looking ultrasound images in real-time including artifacts, which are essential for the interpretation of this data. The simulation is based on a convolution-enhanced ray-tracing approach and uses a deformable mesh model. Deformations of the mesh model are calculated using the PhysX engine. Our method advances the state of the art for real-time capable ultrasound simulators by following the path of the ultrasound pulse, which enables better simulation of ultrasound-specific artifacts. An evaluation of our proposed method in comparison with recent generative slicing-based strategies as well as real ultrasound images is performed. Hereby, a gelatin ultrasound phantom containing syringes filled with different media is scanned with a real transducer. The obtained images are then compared to images which are simulated using a slicing-based technique and our proposed method. The particular benefit of our method is the accurate simulation of ultrasound-specific artifacts, like range distortion, refraction and acoustic shadowing. Several test scenarios are evaluated regarding simulation time, to show the performance and the bottleneck of our method. While being computationally more intensive than slicing techniques, our simulator is able to produce high-quality images in real-time, tracing over 5000 rays through mesh models with more than 2 000 000 triangles of which up to 200 000 may be deformed each frame.

Objective: A novel high-precision approach [lifetime-decomposition measurement (LTDM)] for the assessment of the glomerular filtration rate (GFR) based on clearance measurements of exogenous filtration marker. Methods: The time-correlated single photon counting (TCSPC) acquisition in combination with a new decomposition method allows the separation of signal and background from transcutaneous measurements of GFR. Results: The performance of LTDM is compared versus the commercially available NIC-kidney patch-based system for transcutaneous GFR measurement. Measurements are performed in awake Sprague Dawley (SD) rats. Using the standard concentration required for the NIC-kidney system [7-mg/100-g body weight (b.w.) FITC-Sinistrin] as reference, the mean difference (bias) of the elimination curves GFR between LTDM and NIC-kidney was 4.8%. On the same animal and same day, the capability of LTDM to measure GFR with a FITC-Sinistrin dose reduced by a factor of 200 (35-μg/100-g b.w.) was tested as well. The mean differences (half lives with low dose using LTDM compared with those using first, the NIC-Kidney system and its standard concentration, and second, LTDM with the same concentration as for the NIC-Kidney system) were 3.4% and 4.5%, respectively. Conclusion: We demonstrate that with the LTDM strategy substantial reductions in marker concentrations are possible at the same level of accuracy. Significance: LTDM aims to resolve the issue of the currently necessary large doses of fluorescence tracer required for transcutaneous GFR measurement. Due to substantially less influences from autofluorescence and artifacts, the proposed method outperforms other existing techniques for accurate percutaneous organ function measurement.

3,4-Dimethylpyrazole phosphate (DMPP) is a new nitrification inhibitor with highly favourable properties. It has undergone thorough toxicology and ecotoxicology tests and application-technology experiments, and has been shown to have several distinct advantages compared to the currently used nitrification inhibitors. Application rates of 0.5–1.5 kg ha–1 are sufficient to achieve optimal nitrification inhibition. DMPP can significantly reduce NO3 – leaching, without being liable to leaching itself. DMPP may reduce N2O emission, apparently without a negative effect on CH4 oxidation of the soil. The use of DMPP-containing fertilizers can improve yield. This offers the possibility of saving mineral fertilizer N, reducing the number of N-application rounds, and obtaining higher crop yields with current fertilizer-N rates.

This paper gives an overview of recent work in the field of particle characterization methods which have been developed for the on-line characterization of particulate process in industry. Especially the potential and benefits of optical sensor technology are discussed and illustrated with some practical examples.

An overview of the various goals of particle technology, which have long extended far beyond particle size analysis, is provided by POWTECH. The following examples should serve to illustrate the scope of such measurements and the trends noted in this area: measurements for the monitoring of clean rooms; measurements supporting process engineering developments; and process analysis. There is wide range of instrumentation available for the assessment of dispersed product states. Based on proven principles these instruments are becoming more user friendly and available with improved data evaluation; the methods of evaluation are, unfortunately, still not clear to the user. The current trend is in two directions: (1) simultaneous acquisition of several measurements for more accurate determination of the required quantity or for determination of two different quantities and (2) on-line or in-line measurement, which has to be fast, economical, and safe

Angularly resolved pure rotational excitation of sodium dimers by intermediate energy electrons (150 to 300 eV) is studied using laser state selection technique, under nonresonant collision conditions. The experimental procedure, which is new to electron scattering, is described in detail. The experimental data show large rotational transitions and rotational rainbow structures. The relative cross sections agree well with the close coupling calculations and also with the spectator model predictions.

A multi-channel fluorescence sensor has been developed for process monitoring and fluorescence diagnostics. It comprises a fiber-optic set-up with an immersion probe and an intensity-modulated high power ultraviolet light-emitting diode as a light source for fluorescence excitation. By applying an electronic lock-in procedure, fluorescence signals are selectively detectable at ambient light levels of 1000 000 times higher intensity. The sensor was designed to be compact, low cost and easily adaptable to a wide field of application. The set-up was used to simultaneously monitor three important metabolic fluorophores: NAD(P)H, flavins and porphyrins during the cultivation of a baker's yeast. Moreover, the accumulation and degradation kinetics of protoporphyrin IX induced by 5-aminolevulinic acid on the skin could be recorded by the sensor. The detection limit for protoporphyrin IX was determined to be 4 × 10−11 mol L−1. The linear signal amplification of the sensor and time courses of fluorescence signals monitored during yeast fermentations were validated using a commercial CCD spectrometer. The robust and flexible set-up of the fiber-optic measurement system promises easy implementation of this non-invasive analytical tool to fluorescence monitoring and diagnostics in R&D and production.