Experimental Run Research Articles

Pyrolysation of Pine Merkusii wood bark wastes to produce crude bio-oil using chrome-clay, cr/ clay catalyst as an alternative energy

In this research, bio-oil is produced from pine wood bark waste biomass through pyrolysis using Cr/ clay catalyst. This research aims to produce bio-oil from bark of pine with Cr/ clay catalyst as an alternative fuel. The effect of the ratio of catalyst Cr/ clay weight to biomass and influence of Chromium (Cr) impregnation on clay as catalyst were investigated. Then, the characterisation of physical and chemical characteristics of crude bio-oil produced were measured. For each of the pyrolysis runs, 50 g of pine bark having -100+200 mesh, the Cr/ clay catalysts having weight variations to biomass of 3%, 5%, and 7%, respectively, and then variation of Chromium (Cr) impregnation on clay of 0%, 1%, 2%, and 3%, respectively, were used. For any experimental run, 500 ml of silinap was added to the pyrolysis reactor as thermal homogenized aid. Pyrolysis process was carried out for 120 minutes at 320oC and having stirring speed 300 rpm. As a result, the greatest percentage of bio-oil yield of 65.77% was given of the run having Cr/ clay catalysts 7% and 3% of impregnated Chrome content. Characterisation measurement of bio-oil of physical properties was obtained as follows: density 0.812 g/ml, viscosity 0.902 cSt, acidity 7.626 mg.NaOH/gram, and flash point 31oC, respectively. In addition, the chemical characteristics of the bio-oil were obtained using Gas Chromatography-Mass Spectroscopy (GCMS): analysis found several chemical components as follows, such 9,12-Octadecadienoyl chloride, Cyclohexane, 1-methyl-2-penthyl, Octadecanoic acid, 2-Pentene, 24.4-trimethyl, and Cyclohexane, 3- (3,3-dimethylbutyl).

Hyperons at the BM@N experiment: first results

BM@N (Baryonic Matter at Nuclotron) is the first experiment to be realized at the accelerator complex of NICA-Nuclotron at JINR (Dubna). The aim of the experiment is to study interactions of relativistic heavy ion beams of kinetic energy per nucleon ranging from 1 to 4.5 GeV with fixed targets. First results of the analysis of minimum bias interactions of the deuteron and carbon beams of 4 AGeV kinetic energy with different targets are discussed. Preliminary results from the data collected in the recent experimental run with the argon beam are also presented.

Observer Synthesis for the Adhesion Estimation of a Railway Running Gear

The presented work illustrates an investigation on the observer synthesis for a highly nonlinear railway running gear system. The specific focus is on the longitudinal dynamics and the associated adhesion effects, i.e. the friction conditions between wheel and rail. This interface strongly influences the brake and the traction performance of trains and, thus, its detailed consideration is of crucial importance in terms of safety and comfort.The observer design is accomplished for the experimental running gear developed at the German Aerospace Center (DLR). The article focuses on the first steps of the observer synthesis: (i) the set-up of the observer model, (ii) the selection of an appropriate observer method, (iii) and the validation of the observer in a simulation environment. The determining aspect of the model implementation is the consideration of the nonlinear wheel-rail contact. To cover this nonlinear behavior an Extended Kalman Filter (EKF) is used in combination with a parameter estimator for the friction characteristics in the wheel-rail interfaces. In the end, the received results prove that the observer accurately estimates the system behavior and provides reliable information on the adhesion characteristics and related longitudinal dynamics.Based on this findings one of the upcoming steps at the DLR is to validate the observer in the real-time environment of the test rig. Regarding the use of the presented approach in a train some significant improvements of traction control systems are enabled. A first application could be an enhanced brake control to narrow down the variance of brake distances in daily operation. Furthermore, an advanced usability of the condition based monitoring of traction and brake systems is facilitated with the additional information on the friction conditions.

Acute effect of high-intensity interval training on metabolic and inflammatory markers in obese and overweight adolescents: Pilot study

It is still unclear whether a high-intensity interval exercise (HIIE) protocol is effective for promoting anti-inflammatory and anti-atherogenic responses. The objective of this study was to analyze the acute effects of HIIE on inflammatory and metabolic responses in obese and overweight girls and boys. Initially, the body composition of 19 sedentary volunteers was evaluated. The participants completed an interval experimental run on a treadmill (2:1 min at 95% maximum velocity, totaling ~3 km) and blood samples were collected at rest and immediately after the exercise protocol. Serum was analyzed for interleukins 6 and 10 (IL-6 and IL-10), tumor necrosis factor-α (TNF-α), cortisol, glucose, triacylglycerol (TG), non-esterified fatty acid (NEFA), plasminogen activator inhibitor-1 (PAI-1), and the lipoprotein profile. Under baseline conditions, the groups of boys and girls exhibited differences in the anthropometry measures for fat-free mass ( p = 0.011), gynoid fat ( p = 0.002), visceral fat ( p = 0.004), and glucose ( p = 0.031). After the exercise session, cholesterol, glucose, NEFA, PAI-1, IL-10, and TNF-α did not demonstrate effects for time, group, or interaction under the different conditions. Cortisol (F = 9.018; p = 0.008; partial η2 = 0.347), TG (F = 25.189; p < 0.0001; partial η2 = 0.597), and IL-6 levels (F = 6.543; p = 0.020; partial η2 = 0.278) showed an effect for time. In conclusion, our results demonstrated that HIIE promoted an immune-endocrine response, increasing cortisol and IL-6 levels immediately after the exercise protocol in overweight and obese girls.

Efficacy analysis of a field scale IFAS reactor under different aeration strategies applied at high aeration rates: A statistical comparative analysis for practical feasibility

In the present research study, a field-scale integrated fixed-film activated sludge reactor treating municipal wastewater was examined under three cyclic aeration on/off periods (also known as intermittent aeration), applied at a aeration rate of 110 m3/h (capable to maintain bulk dissolved oxygen in the range of 4.5–5.0 mg/L). The whole experimental campaign was divided into four operational phases (continuous aeration followed by three aeration on/off cycles, expressed in terms of ratio of aeration on/off time, Period I: 150/30 min, Period II: 120/60 min, Period III: 90/60 min). Each experimental run was studied at a hydraulic retention time of 11.1 h and mixed liquor suspended solids concentrations as 2 ± 0.2 g/L. The treatment performance results showed that high rate assisted in achieving the desired performance under applied intermittent aeration conditions. Except nitrogen removal, other performance parameters such as chemical oxygen demand, biological oxygen demand, total suspended solids, ammonia nitrogen, and phosphorus were found to be least affected by on/off control applied in Period I and could cope up with Indian discharge standards. Whereas, Period II and III were not found to be appropriate with respect to desired performance. With respect to nutrient parameters, nitrogen and phosphorus removal rates were significantly deteriorated with increasing aeration off times. A statistical comparison of different operational phases, using analysis of variance and Turkey Post Hoc test, was also done to check the similarity/dissimilarity of applied strategies. The results revealed that period I and continuous aeration phase were quite similar in terms of all performance parameters.

Measurement of the branching fraction and time-dependent CP asymmetry for B0→J/ψπ0 decays

We measure the branching fraction and time-dependent $CP$-violating asymmetry for $B^0\to J/\psi\pi^0$ decays using a data sample of 711 ${\rm fb^{-1}}$ collected on the $\Upsilon(4S)$ resonance by the Belle experiment running at the KEKB $e^+e^-$ collider. The branching fraction is measured to be $\mathcal{B}(B^0\to J/\psi\pi^0) = [1.62\,\pm 0.11~({\rm stat}) \pm0.07~({\rm syst})]\times 10^{-5}$, which is the most precise measurement to date. The measured $CP$ asymmetry parameters are $\mathcal{S} = -0.59\,\pm 0.19~({\rm stat}) \pm 0.03~({\rm syst})$ and $\mathcal{A} = -0.15\,\pm 0.14~({\rm stat})\,^{+0.04}_{-0.03}~({\rm syst})$. The mixing-induced $CP$ asymmetry ($\mathcal{S}$) differs from the case of no $CP$ violation by 3.0 standard deviations, and the direct $CP$ asymmetry ($\mathcal{A}$) is consistent with zero.

System identification based proxy modeling of a reservoir under iWAG

The high computational cost associated with first principle based numerical reservoir models create a barrier for realizing their full potential. Currently, high fidelity proxy models, capable of mimicking the numerical reservoir models, are used to undertake some of the tasks. Nonetheless, large number of experimental simulations are required to generate modeling data. Moreover, experimental realizations are obtained by sampling static geological properties, hence, the resulting proxy model does not honor the dynamic nature of reservoirs, especially during immiscible water alternating gas injection (iWAG) process. In this study, a system identification based proxy modeling algorithm is developed for a reservoir under iWAG. A case study is used to evaluate the algorithm’s performance in reproducing oil, gas and water production rates. By systematically designing the input pattern, only a single experimental run is used to generate modeling data. A blind validation and a cross plot analysis resulted in an average percentage fit of 89% and a tolerance level of up to 10%, respectively. The algorithm can have potential application for optimization of injection scenario and hence for automatic well control during iWAG.

Rates of planimetric change in a proglacial gravel‐bed braided river: Field measurement and physical modelling

AbstractPlanimetric change was measured on daily hydrographs over two meltwater seasons using time‐lapse images of the proglacial, gravel, braided, Sunwapta River, Canada. Significant planimetric change occurred on 10–15 days per year. Area of planimetric change correlated with peak and total daily meltwater hydrograph discharge. A clear threshold discharge can be identified below which no planform activity occurs, an intermediate range over which change occurs conditionally, and a peak flow range at which significant change always occurs. Field conditions were reproduced in a physical model in a laboratory flume. Photogrammetric DEMs of bed morphology and measurements of bedload output were made for each hydrograph experimental run. The physical model results for planimetric change had a threshold discharge for change, and trend with discharge, similar to the field data. The model data also show that planimetric change correlates strongly with volumes of erosion/deposition measured from successive DEMs, and with bedload transport rate. The relation between planimetric change and topographic change is also apparent from previous cross‐section surveys at the field site. The results highlight the planimetric dynamics of braiding rivers in relation to discharge forcing, and the relationship between planimetric change, morphological change, and bedload transport in braided rivers. This also points to the potential use of measurements of planimetric change from time‐lapse imagery as a low‐cost method for high‐frequency monitoring for braiding dynamics and also a surrogate for bedload transport measurement. © 2018 John Wiley & Sons, Ltd.

Improved landfill leachate quality using ozone, UV solar radiation, hydrogen peroxide, persulfate and adsorption processes

Advanced oxidation processes based on ozonation, UV solar radiation, hydrogen peroxide, and persulfate were tested for the complete treatment of a specific landfill leachate. As a post-treatment of the advanced oxidation process, an additional adsorption process was carried out using a natural zeolite. Application of the UVsolar/O3/H2O2 process required 140 min of irradiation and the consumption of 0.67 g/L H2O2 to eliminate 56% and 17% of colour and chemical oxygen demand (COD), respectively. When adding persulfate to the system (UVsolar/O3/H2O2/S2O8−2), colour and COD were reduced by 29% and 77%, respectively, with a 0.2 g/L concentration of S2O8−2 requiring 250 min of irradiation time. In an experimental run with landfill leachate, adsorption post-treatment with a natural zeolite resulted in 36%, 99%, and 18% total reductions in COD, ammonium, and chloride, respectively. In another experimental run, adsorption with a zeolite was used as a pre-treatment for the advanced oxidation process (UVsolar/O3/H2O2 and UVsolar/O3/H2O2/S2O8−2). The results were similar to those for adsorption post-treatment, with 30%, 90%, and 20% total reductions in COD, ammonium, and chloride, respectively. Despite improvements, some measured parameters of treated landfill leachate still exceeded Chilean regulations for water quality. Furthermore, Lactuca sativa seeds did not germinate after irrigation with 100% treated landfill leachate or dilutions above 3%. Finally, EC50 values were enhanced during treatment, going from 0.002% for raw landfill leachate to 1.179% after the adsorption process.

Detection of high-order Lamb waves using an end-face injection of ultrasonic pulses

Abstract In this work, we report the time-of-flight detection of high-order Lamb waves by using an end-face injection of ultrasonic pulses in plates. We used two piezoelectric transducers attached to the opposite edges of a rectangular plate. We applied the Short Time Fourier Transform (STFT) to determine the time-of-flight. We compare the contours of the STFT on the time-frequency spectrogram with the theoretical time-of-flight. This technique defines a broadband map for multiple Lamb waves on the same experimental run. We have found clear evidence not only of the lowest symmetric and antisymmetric modes ( S 0 and A 0 ) but also of higher order modes ( S 1 , A 1 , and S 2 ).

Identifying animal species in camera trap images using deep learning and citizen science

Abstract Ecologists often study wildlife populations by deploying camera traps. Large datasets are generated using this approach which can be difficult for research teams to manually evaluate. Researchers increasingly enlist volunteers from the general public as citizen scientists to help classify images. The growing number of camera trap studies, however, makes it ever more challenging to find enough volunteers to process all projects in a timely manner. Advances in machine learning, especially deep learning, allow for accurate automatic image classification. By training models using existing datasets of images classified by citizen scientists and subsequent application of such models on new studies, human effort may be reduced substantially. The goals of this study were to (a) assess the accuracy of deep learning in classifying camera trap data, (b) investigate how to process datasets with only a few classified images that are generally difficult to model, and (c) apply a trained model on a live online citizen science project. Convolutional neural networks (CNNs) were used to differentiate among images of different animal species, images of humans or vehicles, and empty images (no animals, vehicles, or humans). We used four different camera trap datasets featuring a wide variety of species, different habitats, and a varying number of images. All datasets were labelled by citizen scientists on Zooniverse. Accuracies for identifying empty images across projects ranged between 91.2% and 98.0%, whereas accuracies for identifying specific species were between 88.7% and 92.7%. Transferring information from CNNs trained on large datasets (“transfer‐learning”) was increasingly beneficial as the size of the training dataset decreased and raised accuracy by up to 10.3%. Removing low‐confidence predictions increased model accuracies to the level of citizen scientists. By combining a trained model with classifications from citizen scientists, human effort was reduced by 43% while maintaining overall accuracy for a live experiment running on Zooniverse. Ecology researchers can significantly reduce image classification time and manual effort by combining citizen scientists and CNNs, enabling faster processing of data from large camera trap studies.

Evaluation of factors influencing dairy biofilm formation in filling hoses of food-processing equipment

Biofilms in dairy-processing environments lead to increased opportunities for microbial contamination of processed products. The aim of this work is to investigate the influence of factors that can affect biofilm onset in a dairy-filling test hose. Bacterial composition (monoculture Pseudomonas fragi, polyculture), fat content of milk (1.5%, 3.5%), flow condition (laminar, turbulent), and contact material (PTFE, stainless steel 1.4404) were considered as factors at a constant low temperature of 5.5±0.5°C. Biofilms were visualized by microscopy (CLSM) and analysed by counting viable cells, ATP-bioluminescence assay, and staining method for biomass quantification. The correlation between these methods was evaluated, since the chosen methods detect different characteristics of biofilms. Furthermore, enzymatic cleaning was applied after each experimental run. The results showed that the bacterial composition, material type, and fat content significantly affect the results of viable-cell counting (p≤0.05). Flow conditions and material type both have significant influence upon biomass-quantification results (p≤0.001). The highest positive Pearson correlation was estimated between the ATP-bioluminescence and biomass methods (0.550), while the lowest correlation was found between viable-cell counting and biomass quantification (0.345). Enzymatic treatment showed a good result for the cleaning of the PTFE-hose liner in the dairy-filling hose.

High-throughput multiplexed fluorescence-activated droplet sorting

Fluorescence-activated droplet sorting (FADS) is one of the most important features provided by droplet-based microfluidics. However, to date, it does not allow to compete with the high-throughput multiplexed sorting capabilities offered by flow cytometery. Here, we demonstrate the use of a dielectrophoretic-based FADS, allowing to sort up to five different droplet populations simultaneously. Our system provides means to select droplets of different phenotypes in a single experimental run to separate initially heterogeneous populations. Our experimental results are rationalized with the help of a numerical model of the actuation of droplets in electric fields providing guidelines for the prediction of sorting designs for upscaled or downscaled microsystems.

Development and Application of Interferometric On-Machine Surface Measurement for Ultraprecision Turning Process

The continuing evolution of ultraprecision machining places an increasing need to perform surface measurement in the manufacturing environment. Development of on-machine surface measurement (OMSM) tools for ultraprecision machining processes will enable the reduction of measurement cycle time as well as the potential improvement of machining accuracy. In the present study, an in-house designed interferometer probe is integrated onto an ultraprecision diamond turning machine. System configuration, calibration scheme and various scanning strategies are first presented. The benefit of OMSM preserves the consistency between the machining and measurement coordinate system. Two applications of OMSM for ultraprecision turning process are further investigated. To further improve the surface accuracy, corrective machining is carried out based on the on-machine measured data. The profile accuracy of a cosine curve sample was improved after corrective machining with OMSM. Moreover, process investigation with OMSM was employed to model the effect of process parameters on the form error in ultraprecision cylindrical turning process. OMSM enables the consistent measurement of part coordinates for each experimental run, which is critical for acquiring a deterministic response for empirical modeling. A reduced quadratic model was built by means of response surface methodology and verified by the test for significance of the regression model. The confirmation tests show that the model predicted value conformed to the experimental value with a difference less than 4%.

Developmental validation of a custom panel including 165 Y-SNPs for Chinese Y-chromosomal haplogroups dissection using the ion S5 XL system

Massively parallel sequencing (MPS) technology has the capability to genotype hundreds to thousands of SNPs from multiple samples, with high coverage in a single experimental run. MPS, which enables high-resolution Y haplogrouping from limited DNA resources, has attracted much interest in Y-chromosomal applications, particularly human forensics and anthropological studies. Previously, we selected and designed a 72 Y-SNPs MPS panel aiming at the Chinese population for providing the basic structure of the haplogroup tree, and then additional Y-SNPs were screened out for further subdivision into different populations by using pyrosequencing technology. In the present study, we designed a customized MPS panel that includes 165 Y-SNPs based on our previous studies and evaluated the sequencing performance, sensitivity and the ability of the MPS-SNP panel to analyze case-type samples using the Ion S5 XL System. In the concordant study, only four Y-SNPs presented missing genotypes due to low coverage reads, and five SNPs were prone to being designated heterozygotes, whereas the designation of the other SNPs were fully consistent with the results obtained from other Y-SNP typing tools. The analyst-interpreted Y-SNP profiles demonstrated that the targeted Y-SNPs, except for the nine poorly performing Y-SNPs, performed well and could acquire achievable high-resolution. Moreover, this MPS panel could be adapted to case-type samples, and single source complete profiles could be stably obtained using 1 ng of input DNA. In summary, this MPS Y-SNP panel offers a straightforward sample-to-haplogroup workflow that would be beneficial for paternal lineage classification and forensic pedigree searches, and the present results provide support for the application of MPS technology in SNP analysis.

Concentration-Dependent Diffusion Coefficients of Binary Gas Mixtures Using a Loschmidt Cell with Holographic Interferometry

A model-based experimental approach is presented to measure concentration-dependent diffusion coefficients of binary gases from a single experimental run. The diffusion experiments are performed with a Loschmidt cell combined with holographic interferometry that has been improved in Part I of this paper (Wolff et al. in Int. J. Thermophys. 2018, https://doi.org/10.1007/s10765-018-2450-8 ). Measurements are taken with the system helium–krypton. Besides highly accurate measurements, a highly accurate diffusion model is required to retrieve the weak concentration dependence of the diffusion coefficient. We derive a consistent diffusion model considering real gas effects and the concentration dependence of the diffusion coefficient. The model describes the experimental fringe data with deviations of less than 0.2 interference fringe orders, which corresponds to a relative deviation of 0.17 % indicating high quality of both the experimental data and the employed model. Therefore, the concentration dependence of the helium–krypton diffusion coefficient could be successfully retrieved from a single experiment of mixing pure gases. Thus, the presented approach allows for the efficient characterization of diffusion in gases.

Randomness Extraction from Bell Violation with Continuous Parametric Down-Conversion.

We present a violation of the Clauser-Horne-Shimony-Holt inequality without the fair sampling assumption with a continuously pumped photon pair source combined with two high efficiency superconducting detectors. Because of the continuous nature of the source, the choice of the duration of each measurement round effectively controls the average number of photon pairs participating in the Bell test. We observe a maximum violation of S=2.016 02(32) with an average number of pairs per round of ≈0.32, compatible with our system overall detection efficiencies. Systems that violate a Bell inequality are guaranteed to generate private randomness, with the randomness extraction rate depending on the observed violation and on the repetition rate of the Bell test. For our realization, the optimal rate of randomness generation is a compromise between the observed violation and the duration of each measurement round, with the latter realistically limited by the detection time jitter. Using an extractor composably secure against quantum adversary with quantum side information, we calculate an asymptotic rate of ≈1300 random bits/s. With an experimental run of 43min, we generated 617 920 random bits, corresponding to ≈240 random bits/s.

New Device for the Treatment of Functional Ischemic Mitral Regurgitation: Proof of Concept in an In Vitro Model.

Optimal surgical treatment of functional ischemic mitral regurgitation (FIMR) is still controversy. Due to the underlying pathophysiology, stand-alone ring annuloplasty is assumed with a high recurrence rate of mitral regurgitation, thus additional subvalvular repair techniques might improve the results. This in vitro study introduces a new device for subvalvular mitral valve repair. We developed a new device for subvalvular mitral valve repair, consisting of two frames for papillary muscle (PM) attachment, which are connected with two holding bars serving for fixation of the device on an annuloplasty ring. In the first experimental run, porcine mitral valves including the chordae tendineae and PMs were fixated on a holding device, consisting of a holding ring simulating mitral annulus dilation and height-adjustable frames for PM attachment simulating leaflet tethering. In vitro regurgitant volume was determined in a pulse duplicator. Afterward, the frames for PM attachment were replaced by our newly developed device and the measurements were repeated. In the model simulating FIMR, the regurgitant volume was 44.3 ± 12.38 mL/stroke. After subvalvular reconstruction with our new device, the regurgitant volume was significantly reduced to 33.1 ± 11.68 mL/stroke (p = 0.009). In this specific in vitro model, our new device for subvalvular mitral valve reconstruction led to a significant reduction of the regurgitant volume, thus representing a promising technique to potentially improve the results of mitral reconstruction in ischemic functional mitral valve regurgitation. Additional studies are required to further investigate and improve our device.

Drilling of micro-holes on titanium alloy using pulsed Nd:YAG laser: Parametric appraisal and prediction of performance characteristics

Laser drilling is a preferable method in drilling micro and slender holes because of its non-physical contact between the tool and the workpiece leading to elimination of the problems like chatter and vibration. In this article, an experimental investigation of the laser drilling process is carried out on thin sheet (0.5 mm) of titanium alloy (Ti6Al4V) using pulsed Nd:YAG laser. The study investigates the effect of laser parameters such as laser energy, pulse repetition rate, pulse width and gas pressure on hole quality characteristics, namely, circularity at entry and exit, taper and spatter area. Taguchi’s L27 orthogonal array is adopted for conducting the experiments to establish significance of control parameters on the performance measures with less number of experimental run. Analysis of variance shows that laser energy and pulse width significantly influence on circularity, taper and spatter area. Optimal parameter setting for all the performance measures is suggested. Statistically valid empirical models relating hole quality characteristics with laser parameters have been developed based on least square regression analysis. Backpropagation artificial neural network is used predict the output responses considering laser process parameters as inputs. A mean square error within 5% for both the training and testing data suggests the adequacy and robustness of the proposed artificial neural network model. Variation of performance measures with respect to process parameters is predicted through the well-trained artificial neural network model. The pattern of variation exhibits good agreement with the main effect plots obtained through Taguchi method. Artificial neural network model produces mean relative error of 0.001, 0.001, 0.0437 and 0.0234 for circularity at entry, circularity at exit, taper and spatter area, respectively, when compared with experimental values. Since small values of mean relative error are obtained, the proposed artificial neural network model can be satisfactorily used for prediction of quality characteristics of laser micro-drilled holes.

In vitro study of new combinations for local antibiotic therapy with calcium sulphate - Near constant release of ceftriaxone offers new treatment options.

Introduction: Local application of antibiotics provides high concentrations at the site of interest, with minimal systemic toxicity. Carrier materials might help manage dead space. Calcium sulphate (CaSO4) has a dissolution time that only slightly exceeds the usually recommended duration of systemic antibiotic treatments. This in vitro study evaluates compatibility, release kinetics and antibacterial activity of new combinations of antibiotics with CaSO4 as carrier material.Methods: CaSO4 pellets added with 8% w/w antibiotic powder were exposed once in phosphate-buffered saline (PBS) solution and once in bovine plasma, in an elution experiment run over 6 weeks at 37 °C. Antibiotic elution was examined at various time points. Concentration was measured by liquid chromatography with tandem mass spectrometry. Antimicrobial activity was checked with an agar diffusion test.Results: Piperacillin-tazobactam, ceftazidime, cefepime, and meropenem showed fast reduction of concentration and activity. Flucloxacillin and cefuroxime remained present in relevant concentrations for 4 weeks. Ciprofloxacin, levofloxacin and clindamycin lasted for 6 weeks, but also at cell toxic concentrations. Ceftriaxone showed a near-constant release with only a small reduction of concentration from 130 to 75 mg/l. Elution profiles from PBS and plasma were comparable.Conclusion: CaSO4 provides new possibilities in the local treatment of bone and joint infections. Ceftriaxone appears to be of particular interest in combination with CaSO4. Release persists at clinically promising concentrations, and appears to have a depot-like slow release from CaSO4, with only a small reduction in activity and concentration over 6 weeks. To the best of our knowledge, such a particular persistent release never was described before, for any antibiotic in combination with a carrier material for local application.