@article{JildehOberlaenderKirchneretal.2018, author = {Jildeh, Zaid B. and Oberl{\"a}nder, Jan and Kirchner, Patrick and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef}, title = {Thermocatalytic Behavior of Manganese (IV) Oxide as Nanoporous Material on the Dissociation of a Gas Mixture Containing Hydrogen Peroxide}, series = {Nanomaterials}, volume = {8}, journal = {Nanomaterials}, number = {4}, publisher = {MDPI}, address = {Basel}, issn = {2079-4991}, doi = {10.3390/nano8040262}, pages = {Artikel 262}, year = {2018}, abstract = {In this article, we present an overview on the thermocatalytic reaction of hydrogen peroxide (H₂O₂) gas on a manganese (IV) oxide (MnO₂) catalytic structure. The principle of operation and manufacturing techniques are introduced for a calorimetric H₂O₂ gas sensor based on porous MnO₂. Results from surface analyses by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) of the catalytic material provide indication of the H₂O₂ dissociation reaction schemes. The correlation between theory and the experiments is documented in numerical models of the catalytic reaction. The aim of the numerical models is to provide further information on the reaction kinetics and performance enhancement of the porous MnO₂ catalyst.}, language = {en} } @article{JildehKirchnerBaltesetal.2019, author = {Jildeh, Zaid B. and Kirchner, Patrick and Baltes, Klaus and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef}, title = {Development of an in-line evaporation unit for the production of gas mixtures containing hydrogen peroxide - numerical modeling and experimental results}, series = {International Journal of Heat and Mass Transfer}, volume = {143}, journal = {International Journal of Heat and Mass Transfer}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0017-9310}, doi = {10.1016/j.ijheatmasstransfer.2019.118519}, pages = {Article number 118519}, year = {2019}, abstract = {Hydrogen peroxide (H2O2) is a typical surface sterilization agent for packaging materials used in the pharmaceutical, food and beverage industries. We use the finite-elements method to analyze the conceptual design of an in-line thermal evaporation unit to produce a heated gas mixture of air and evaporated H2O2 solution. For the numerical model, the required phase-transition variables of pure H2O2 solution and of the aerosol mixture are acquired from vapor-liquid equilibrium (VLE) diagrams derived from vapor-pressure formulations. This work combines homogeneous single-phase turbulent flow with heat-transfer physics to describe the operation of the evaporation unit. We introduce the apparent heat-capacity concept to approximate the non-isothermal phase-transition process of the H2O2-containing aerosol. Empirical and analytical functions are defined to represent the temperature- and pressure-dependent material properties of the aqueous H2O2 solution, the aerosol and the gas mixture. To validate the numerical model, the simulation results are compared to experimental data on the heating power required to produce the gas mixture. This shows good agreement with the deviations below 10\%. Experimental observations on the formation of deposits due to the evaporation of stabilized H2O2 solution fits the prediction made from simulation results.}, language = {en} } @article{JildehKirchnerOberlaenderetal.2020, author = {Jildeh, Zaid B. and Kirchner, Patrick and Oberl{\"a}nder, Jan and Vahidpour, Farnoosh and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef}, title = {Development of a package-sterilization process for aseptic filling machines: A numerical approach and validation for surface treatment with hydrogen peroxide}, series = {Sensor and Actuators A: Physical}, volume = {303}, journal = {Sensor and Actuators A: Physical}, number = {111691}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0924-4247}, doi = {10.1016/j.sna.2019.111691}, year = {2020}, abstract = {Within the present work a sterilization process by a heated gas mixture that contains hydrogen peroxide (H₂O₂) is validated by experiments and numerical modeling techniques. The operational parameters that affect the sterilization efficacy are described alongside the two modes of sterilization: gaseous and condensed H₂O₂. Measurements with a previously developed H₂O₂ gas sensor are carried out to validate the applied H₂O₂ gas concentration during sterilization. We performed microbiological tests at different H₂O₂ gas concentrations by applying an end-point method to carrier strips, which contain different inoculation loads of Geobacillus stearothermophilus spores. The analysis of the sterilization process of a pharmaceutical glass vial is performed by numerical modeling. The numerical model combines heat- and advection-diffusion mass transfer with vapor-pressure equations to predict the location of condensate formation and the concentration of H₂O₂ at the packaging surfaces by changing the gas temperature. For a sterilization process of 0.7 s, a H₂O₂ gas concentration above 4\% v/v is required to reach a log-count reduction above six. The numerical results showed the location of H₂O₂ condensate formation, which decreases with increasing sterilant-gas temperature. The model can be transferred to different gas nozzle- and packaging geometries to assure the absence of H₂O₂ residues.}, language = {en} } @article{JildehWagnerSchoening2021, author = {Jildeh, Zaid B. and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef}, title = {Sterilization of Objects, Products, and Packaging Surfaces and Their Characterization in Different Fields of Industry: The Status in 2020}, series = {physica status solidi (a) applications and materials science}, volume = {218}, journal = {physica status solidi (a) applications and materials science}, number = {13}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6319}, doi = {10.1002/pssa.202000732}, pages = {27 Seiten}, year = {2021}, abstract = {The treatment method to deactivate viable microorganisms from objects or products is termed sterilization. There are multiple forms of sterilization, each intended to be applied for a specific target, which depends on—but not limited to—the thermal, physical, and chemical stability of that target. Herein, an overview on the currently used sterilization processes in the global market is provided. Different sterilization techniques are grouped under a category that describes the method of treatment: radiation (gamma, electron beam, X-ray, and ultraviolet), thermal (dry and moist heat), and chemical (ethylene oxide, ozone, chlorine dioxide, and hydrogen peroxide). For each sterilization process, the typical process parameters as defined by regulations and the mode of antimicrobial activity are summarized. Finally, the recommended microorganisms that are used as biological indicators to validate sterilization processes in accordance with the rules that are established by various regulatory agencies are summarized.}, language = {en} } @article{KarschuckKaulenPoghossianetal.2021, author = {Karschuck, Tobias and Kaulen, Corinna and Poghossian, Arshak and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef}, title = {Gold nanoparticle-modified capacitive field-effect sensors: Studying the surface density of nanoparticles and coupling of charged polyelectrolyte macromolecules}, series = {Electrochemical Science Advances}, volume = {2}, journal = {Electrochemical Science Advances}, number = {5}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0938-5193}, doi = {10.1002/elsa.202100179}, pages = {10 Seiten}, year = {2021}, abstract = {The coupling of ligand-stabilized gold nanoparticles with field-effect devices offers new possibilities for label-free biosensing. In this work, we study the immobilization of aminooctanethiol-stabilized gold nanoparticles (AuAOTs) on the silicon dioxide surface of a capacitive field-effect sensor. The terminal amino group of the AuAOT is well suited for the functionalization with biomolecules. The attachment of the positively-charged AuAOTs on a capacitive field-effect sensor was detected by direct electrical readout using capacitance-voltage and constant capacitance measurements. With a higher particle density on the sensor surface, the measured signal change was correspondingly more pronounced. The results demonstrate the ability of capacitive field-effect sensors for the non-destructive quantitative validation of nanoparticle immobilization. In addition, the electrostatic binding of the polyanion polystyrene sulfonate to the AuAOT-modified sensor surface was studied as a model system for the label-free detection of charged macromolecules. Most likely, this approach can be transferred to the label-free detection of other charged molecules such as enzymes or antibodies.}, language = {en} } @article{VahidpourGuthmanArreolaetal.2022, author = {Vahidpour, Farnoosh and Guthman, Eric and Arreola, Julia and Alghazali, Yousef H. M. and Wagner, Torsten and Sch{\"o}ning, Michael Josef}, title = {Assessment of Various Process Parameters for Optimized Sterilization Conditions Using a Multi-Sensing Platform}, series = {Foods}, volume = {11}, journal = {Foods}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2304-8158}, doi = {10.3390/foods11050660}, pages = {Artikel 660}, year = {2022}, abstract = {In this study, an online multi-sensing platform was engineered to simultaneously evaluate various process parameters of food package sterilization using gaseous hydrogen peroxide (H₂O₂). The platform enabled the validation of critical aseptic parameters. In parallel, one series of microbiological count reduction tests was performed using highly resistant spores of B. atrophaeus DSM 675 to act as the reference method for sterility validation. By means of the multi-sensing platform together with microbiological tests, we examined sterilization process parameters to define the most effective conditions with regards to the highest spore kill rate necessary for aseptic packaging. As these parameters are mutually associated, a correlation between different factors was elaborated. The resulting correlation indicated the need for specific conditions regarding the applied H₂O₂ gas temperature, the gas flow and concentration, the relative humidity and the exposure time. Finally, the novel multi-sensing platform together with the mobile electronic readout setup allowed for the online and on-site monitoring of the sterilization process, selecting the best conditions for sterility and, at the same time, reducing the use of the time-consuming and costly microbiological tests that are currently used in the food package industry.}, language = {en} }