Erosion behaviour of human, bovine and equine dental hard tissues.

Dental hard tissues from different species are used in dental research, but little is known about their comparability. The aim of this study was to compare the erosive behaviour of dental hard tissues (enamel, dentin) obtained from human, bovine and equine teeth. In addition, the protective effect of the pellicle on each hard tissue under erosive conditions was determined. In situ pellicle formation was performed for 30 min on enamel and dentin samples from all species in four subjects. Calcium and phosphate release was assessed during 120 s of HCl incubation on both native and pellicle-covered enamel and dentin samples. SEM and TEM were used to examine surface changes in native enamel and dentin samples after acid incubation and the ultrastructure of the pellicle before and after erosive exposure. In general, bovine enamel and dentin showed the highest degree of erosion after acid exposure compared to human and equine samples. Erosion of human primary enamel tended to be higher than that of permanent teeth, whereas dentin showed the opposite behaviour. SEM showed that eroded equine dentin appeared more irregular than human or bovine dentin. TEM studies showed that primary enamel appeared to be most susceptible to erosion.

Report of three patients with extensive neurocysticercosis in rural southern Tanzania: neurological, serological and neuroradiological findings.

BACKGROUND: Neurocysticercosis (NCC) is common in eastern Africa, but disease presentation varies considerably. Most patients have single or few NCC-typical lesions in their brain but some present with a large number of lesions. We present three patients with positive antibody-based serology for Taenia solium cysticercosis screened at the Vwawa district hospital, Mbozi district, southern Tanzania, in whom extensive NCC was confirmed by neuroimaging. CASE PRESENTATIONS: Patient 1 was a 55-year-old female from the tribe Malila smallholder farmer who has had four generalized tonic-clonic epileptic seizures over a period of 11 years and one episode of transient left hemiparesis one year before seizure onset. The patient also reported monthly to weekly episodes of severe, progressive, unilateral headache. The computed tomography (CT) scan of the brain showed 25 NCC lesions of which 15 were in the vesicular stage. Patient 2 was a 30-year-old male from tribe Nyha mechanic who reported monthly episodes of moderate to severe, progressive, bilateral headache, but no epileptic seizures. The CT scan showed 63 NCC lesions of which 50 were in the vesicular stage. Patient 3 was a 54-year-old female from the tribe Malila smallholder farmer who suffered from frequent generalized tonic-clonic epileptic seizures with potential signs of focal seizure onset. She also reported weekly to daily episodes of severe, progressive, unilateral headache. The CT scan showed 29 NCC lesions of which 28 were in the vesicular stage. CONCLUSIONS: Clinical presentation of NCC with multiple brain lesions varies considerably ranging from few epileptic seizures and severe headache to severe epilepsy with frequent epileptic seizures. Individuals with neurological signs/symptoms that may be due to NCC, based for example on epidemiological criteria or serological evidence of cysticercosis, are recommended to undergo neuroimaging before anthelminthic treatment is considered.

Efficacy and safety of antiparasitic therapy for neurocysticercosis in rural Tanzania: a prospective cohort study.

PURPOSE: Neurocysticercosis is common in regions endemic for Taenia solium. Active-stage neurocysticercosis can be treated with antiparasitic medication, but so far no study on efficacy and safety has been conducted in Africa. METHODS: We conducted a prospective cohort study on treatment of neurocysticercosis in Tanzania between August 2018 and January 2022. Patients were initially treated with albendazole (15 mg/kg/d) for 10 days and followed up for 6 months. Additionally in July 2021, all participants who then still had cysts were offered a combination therapy consisting of albendazole (15 mg/kg/d) and praziquantel (50 mg/kg/d). Antiparasitic treatment was accompanied by corticosteroid medication and anti-seizure medication if the patient had experienced epileptic seizures before treatment. RESULTS: Sixty-three patients were recruited for this study, of whom 17 had a complete follow-up after albendazole monotherapy. These patients had a total of 138 cysts at baseline, of which 58 (42%) had disappeared or calcified by the end of follow-up. The median cyst reduction was 40% (interquartile range 11-63%). Frequency of epileptic seizures reduced considerably (p < 0.001). Three patients had all active cysts resolved or calcified and of the remaining 14, eight received the combination therapy which resolved 63 of 66 cysts (95%). Adverse events were infrequent and mild to moderate during both treatment cycles. CONCLUSION: Cyst resolution was unsatisfactory with albendazole monotherapy but was very high when it was followed by a combination of albendazole and praziquantel.

Post-acute phase and sequelae management of epidermal necrolysis: an international, multidisciplinary DELPHI-based consensus.

BACKGROUND: Long-term sequelae are frequent and often disabling after epidermal necrolysis (Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)). However, consensus on the modalities of management of these sequelae is lacking. OBJECTIVES: We conducted an international multicentric DELPHI exercise to establish a multidisciplinary expert consensus to standardize recommendations regarding management of SJS/TEN sequelae. METHODS: Participants were sent a survey via the online tool "Survey Monkey" consisting of 54 statements organized into 8 topics: general recommendations, professionals involved, skin, oral mucosa and teeth, eyes, genital area, mental health, and allergy workup. Participants evaluated the level of appropriateness of each statement on a scale of 1 (extremely inappropriate) to 9 (extremely appropriate). Results were analyzed according to the RAND/UCLA Appropriateness Method. RESULTS: Fifty-two healthcare professionals participated. After the first round, a consensus was obtained for 100% of 54 initially proposed statements (disagreement index < 1). Among them, 50 statements were agreed upon as 'appropriate'; four statements were considered 'uncertain', and ultimately finally discarded. CONCLUSIONS: Our DELPHI-based expert consensus should help guide physicians in conducting a prolonged multidisciplinary follow-up of sequelae in SJS-TEN.

Tailoring the composition of biocopolyester blends for dimensionally accurate extrusion-based printing, annealing and steam sterilization.

Fused filament fabrication (FFF) represents a straightforward additive manufacturing technique applied in the medical sector for personalized patient treatment. However, frequently processed biopolymers lack sufficient thermal stability to be used as auxiliary devices such as surgical guides. The aim of this study was to evaluate the dimensional accuracy of experimental biocopolyester blends with improved thermal characteristics after printing, annealing and sterilization. A total of 160 square specimens and 40 surgical guides for oral implant placement were printed. One subgroup of each material (n = 10) underwent thermal annealing before both subgroups were subjected to steam sterilization (134 °C; 5 min). Specimens were digitized and the deviation from the original file was calculated. The thermal behavior was analyzed using differential scanning calorimetry and thermogravimetric analysis. A one-way ANOVA and t-tests were applied for statistical analyses (p < 0.05). All biocopolyester blends showed warpage during steam sterilization. However, the material modification with mineral fillers (21-32 wt%) and nucleating agents in combination with thermal annealing showed a significantly reduced warpage of printed square specimens. Geometry of the printing object seemed to affect dimensional accuracy, as printed surgical guides showed less distortion between the groups. In summary, biocopolyesters did benefit from fillers and annealing to improve their dimensional stability.

Energetics, but not development, is impacted in coral embryos exposed to ocean acidification.

In light of the chronic stress and mass mortality reef-building corals face under climate change, it is critical to understand the processes driving reef persistence and replenishment, including coral reproduction and development. Here, we quantified gene expression and sensitivity to ocean acidification across a set of developmental stages in the rice coral, Montipora capitata. Embryos and swimming larvae were exposed to pH treatments of 7.8 (ambient), 7.6 (low) and 7.3 (extreme low) from fertilization to 9 days post-fertilization. Embryo and larval volume, and stage-specific gene expression were compared between treatments to determine the effects of acidified seawater on early development. Although there was no measurable size differentiation between pH treatments at the fertilized egg and prawn chip (9 h post-fertilization) stages, early gastrulae and larvae raised in reduced pH treatments were significantly smaller than those raised in ambient seawater, suggesting an energetic cost to developing under low pH. However, no differentially expressed genes were found until the swimming larval stage. Notably, gene expression patterns of larvae developing at pH 7.8 and pH 7.3 were more similar than those of larvae developing at pH 7.6. Larvae from pH 7.6 showed upregulation of genes involved in cell division, regulation of transcription, lipid metabolism and response to oxidative stress in comparison to the other two treatments. Although low pH appears to increase energetic demands and trigger oxidative stress in larvae, the developmental process is robust to this at a molecular level, with the swimming larval stage reached in all pH treatments.

Visible and Near-Infrared hyperspectral imaging (HSI) can reliably quantify CD3 and CD45 positive inflammatory cells in myocarditis: Pilot study on formalin-fixed paraffin-embedded specimens from myocard obtained during autopsy.

INTRODUCTION: To implement Hyperspectral Imaging (HSI) as a tool for quantifying inflammatory cells in tissue specimens by the example of myocarditis in a collective of forensic patients. MATERIAL AND METHODS: 44 consecutive patients with suspected myocardial inflammation at autopsy, diagnosed between 2013 and 2018 at the Institute of ForensicMedicine, Medical University of Innsbruck, were selected for this study. Using the IMEC SNAPSCAN camera, visible and near infrared hyperspectral images were collected from slides stained with CD3 and CD45 to assess quantity and spatial distribution of positive cells. Results were compared with visual assessment (VA) and conventional digital image analysis (DIA). RESULTS: Finally, specimens of 40 patients were evaluated, of whom 36 patients (90%) suffered from myocarditis, two patients (5%) had suspected healing/healed myocarditis, and two did no have myocarditis (5%). The amount of CD3 and CD45 positive cells did not differ significantly between VA, HSI, and DIA (pVA/HSI/DIA = 0.46 for CD3 and 0.81 for CD45). Cohens Kappa showed a very high correlation between VA versus HSI, VA versus DIA, and HSI versus DIA for CD3 (Cohens Kappa = 0.91, 1.00, and 0.91, respectively). For CD45 an almost as high correlation was seen for VA versus HSI and HSI versus DIA (Cohens Kappa = 0.75 and 0.70) and VA versus DIA (Cohens Kappa = 0.89). CONCLUSION: HSI is a reliable and objective method to count inflammatory cells in tissue slides of suspected myocarditis. Implementation of HSI in digital pathology might further expand the possibility of a sophisticated method.

UK dogs eating raw meat diets have higher risk of Salmonella and antimicrobial-resistant Escherichia coli faecal carriage.

OBJECTIVES: To compare detection of Salmonella species and antimicrobial-resistant Escherichia coli in the faeces of dogs eating raw meat or non-raw diets and examine risk factors for their carriage. MATERIALS AND METHODS: Canine faecal samples (raw fed n=114; non-raw fed n=76) were collected from May to July 2015 from across the UK. Enrichment and selective culture and biochemical and PCR assays were used to identify isolates. Escherichia coli underwent susceptibility testing to a range of antimicrobials, including third-generation cephalosporins; PCR assays were used to detect antimicrobial-resistant genes. Questionnaires were used to collect data on independent variables as risks for antimicrobial-resistant (resistant to ≥1 tested antimicrobial), multi-drug-resistant (resistant to ≥3 antimicrobial classes) and third-generation cephalosporin resistant Escherichia coli. RESULTS: Antimicrobial-resistant, multi-drug-resistant and third-generation cephalosporin resistant Escherichia coli were significantly more likely to be detected in raw fed (54, 25 and 31%, respectively) compared to non-raw fed (17, 4 and 4%, respectively) dogs; Salmonella species were detected in eight (4%) raw fed dogs only. CLINICAL SIGNIFICANCE: Raw fed dogs may be a source of Salmonella species and Escherichia coli, resistant to highest priority critically important antimicrobials, representing a potential animal welfare and public health issue. Owners should be aware of the risks, especially households with members, both human and canine, who are very young, elderly or immunocompromised.

Inhibiting Type VI Secretion System Activity with a Biomimetic Peptide Designed To Target the Baseplate Wedge Complex.

Human health is threatened by bacterial infections that are increasingly resistant to multiple drugs. A recently emerged strategy consists of disarming pathogenic bacteria by targeting and blocking their virulence factors. The type VI secretion system (T6SS) is a widespread secretion nanomachine encoded and employed by pathogenic strains to establish their virulence process during host invasion. Given the conservation of T6SS in several human bacterial pathogens, the discovery of an effective broad-spectrum T6SS virulence blocker represents an attractive target for development of antivirulence therapies. Here, we identified and validated a protein-protein interaction interface, TssK-TssG, as a key factor in the assembly of the T6SS baseplate (BP) complex in the pathogen enteroaggregative Escherichia coli (EAEC). In silico and biochemical studies revealed that the determinants of the interface are broadly conserved among pathogenic species, suggesting a role for this interface as a target for T6SS inhibition. Based on the high-resolution structure of the TssKFGE wedge complex, we rationally designed a biomimetic cyclic peptide (BCP) that blocks the assembly of the EAEC BP complex and inhibits the function of T6SS in bacterial cultures. Our BCP is the first compound completely designed from prior structural knowledge with anti-T6SS activity that can be used as a model to target human pathogens. IMPORTANCE New therapeutic options are urgently needed to fight drug-resistant and life-threatening infections. In contrast to antibiotics that inhibit the growth pathways of bacteria, the antivirulence strategy is a promising approach to disarm pathogens by interfering with bacterial virulence factors without exerting evolutionary pressure. The type VI secretion system (T6SS) is used by many pathogens, including members of the antibiotic-resistant ESKAPE bacteria (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.), to establish their virulence during the invasion of the human host. Although the T6SS is undoubtedly involved in pathogenesis, strategies targeting this virulence factor are crucially lacking. Here, we used a combination of genetics, microbiology, biochemical, biophysics, and bioinformatics approaches to rationally design a biomimetic peptide that interferes with T6SS assembly and functioning. This study represents a novel proof of concept for an antivirulence strategy which aims to interfere with the assembly of the T6SS.

Random-pattern versus perforator-based adipocutaneous skin paddles for postoperative monitoring of free muscle flaps-a comparative retrospective cohort study.

INTRODUCTION: Free microvascular muscle flaps represent well-established reconstructive options for complex soft tissue defects. However, due to their lack of cutaneous capillary beds, they are difficult to monitor postoperatively. To this end, random and axial-pattern adipocutaneous skin paddles are often included. The objective of the study was to compare the impact of random-pattern versus perforator-based adipocutaneous skin paddles on operative efficacy and muscle flap safety. METHODS: Between August 2014 and July 2016, a total of 120 free muscle flaps were included in this retrospective monocentric cohort study. Based on their skin-paddle type, they were either grouped into a 'perforator-based' (group Pb) or 'random-pattern' (group Rp) cohort. The electronic medical records and operative reports of all patients were subsequently reviewed and patient, defect, and flap characteristics of both groups were compared. The effect of the competing skin paddle types on the overall operative time, incidences of flap loss or microvascular complications, and total length of hospital stay were then assessed. RESULTS: Group Pb comprised 72 flaps, whereas 48 flaps constituted group Rp. Patient, defect, and flap characteristics were similar between both groups. Groups Pb and Rp were comparable regarding patient age (group Pb: 61 (10-90) vs. Rp: 59 (13-81), p = 0.556), ASA (American Society of Anesthesiologists) class (group Pb: 3 (1-4) vs. Rp 3 (1-3), p = 0.977), and comorbidities, summarized by the Charlson comorbidity index (CCI; group Pb: 1 (0-4 vs. Rp: 1 (0-5), p = 0.295). Both types of monitoring skin paddles were equally reliable. There was no significant difference in the mean operation time between both groups (group Pb: 373 ±â€¯122 min vs. Rp: 342 ±â€¯84 min, p = 0.124). In-patient treatment after flap surgery and total length of hospital stay were significantly shorter in group Pb (group Pb: 24 ±â€¯10 days vs. Rp: 32 ±â€¯17 days, p = 0.002 and group Pb: 39 ±â€¯15 vs. Rp: 48 ±â€¯24, p = 0.022). CONCLUSION: Perforator-based skin paddles are a reliable tool for postoperative perfusion monitoring of free muscle flaps and help avoid additional surgical interventions as opposed to their random-pattern counterparts. Thus, the overall and postoperative length of hospital stay is significantly reduced.

[Establishing and evaluating a multinational Science Academy: A new tool for fostering scientific young talents in microsurgical research - a Consensus Statement of the DAM]. / Etablierung und Evaluation einer multinationalen Wissenschaftsakademie: Ein neues Modell zur Stärkung des wissenschaftlichen Nachwuchses in der mikrochirurgischen Forschung ­ Ein Konsensus Papier der DAM.

BACKGROUND: The formation of professional networks and cooperations - in addition to any qualified good education - seems fundamental for a successful career. In a number of disciplines, various symposia or conferences exist. In the field of microsurgery, however, a specific, guided and designated opportunity for junior scientists to network with one another has been missing so far. METHODS: In 2017, a science academy was initiated for the first time by the German-speaking Association for Nerves and Vessels (DAM) with the goal of bringing together and networking microsurgically researching young physicians and scientists. This was intended to happen on a small scale once a year in order to develop synergies for joint research projects. For this purpose, motivated junior researchers were individually selected by their mentors and sent to the academy by the boards of research institutions that are organized in the DAM. After getting to know each other in a relaxed atmosphere, the participants were given the opportunity to present their respective research project within the framework of thematic blocks and moderated by experienced mentors. Each presentation was followed by a round table discussion and small group work, in which knowledge and methods were exchanged and points of contact for possible later cooperation were identified. RESULTS: In the past 3 years, the DAM Science Academy proved to be an optimal format to initiate and promote networks of young researchers comprising microsurgically interested physicians and scientists. There were many lively and in-depth discussions, which were mainly due to the open working atmosphere and the obligation to confidentiality. Most of the synergies were shown i. a. in the field of angiogenesis, bioreactor, carcinoma-ADSC interactions, stem cells, AV loop model, ischemia/reperfusion, and nerve regeneration. The participants consistently gave a very positive feedback in the final evaluation with the wish to continue this academy. CONCLUSION: The DAM Science Academy can be considered a highly suitable complemental platform to the existing networking opportunities among microsurgical researchers. Experience so far suggests that this will hopefully result in long-term cooperations and a permanent transfer of knowledge among the participants.

[The "safe" flap - Preoperative perforator-mapping and intraoperative perfusion assessment to reduce flap-associated morbidity - Consensus statement of the German Speaking Working Group for Microsurgery of the Peripheral Nerves and Vessels]. / Der sichere Lappen ­ Präoperatives Gefäß-Mapping und intraoperative Perfusionsmessung zur Reduktion der lappenbedingten Morbidität.

Reconstructive microsurgery using free and pedicled flaps has become a reliable method with a high success rate. Preoperative perforator mapping and intraoperative assessment of perfusion might further reduce flap-associated morbidity.There are various techniques for perforator mapping and perfusion measurement, but no guidelines regarding their use. Therefore, an expert panel at the 40th Annual Meeting of the German-Speaking Working Group for Microsurgery of the Peripheral Nerves and Vessels (DAM) discussed and critically reviewed the current literature. The consensus statement represents the expert opinion based on the available literature and provides recommendations regarding the use of preoperative perforator mapping and intraoperative perfusion measurement.

Genetic resistance determinants to fusidic acid and chlorhexidine in variably susceptible staphylococci from dogs.

BACKGROUND: Concern exists that frequent use of topically-applied fusidic acid (FA) and chlorhexidine (CHX) for canine pyoderma is driving clinically relevant resistance, despite rare description of FA and CHX genetic resistance determinants in canine-derived staphylococci. This study aimed to determine minimum inhibitory concentrations (MICs) and investigate presence of putative resistance determinants for FA and CHX in canine-derived methicillin-resistant (MR) and -susceptible (MS) staphylococci. Plasmid-mediated resistance genes (fusB, fusC, fusD, qacA/B, smr; PCR) and MICs (agar dilution) of FA and CHX were investigated in 578 staphylococci (50 MR S. aureus [SA], 50 MSSA, 259 MR S. pseudintermedius [SP], 219 MSSP) from Finland, U.S.A., North (NUK) and South-East U.K. (SEUK) and Germany. In all isolates with FA MIC ≥64 mg/L (n = 27) fusA and fusE were amplified and sequenced. RESULTS: FA resistance determinants (fusA mutations n = 24, fusB n = 2, fusC n = 36) were found in isolates from all countries bar U.S.A. and correlated with higher MICs (≥1 mg/L), although 4 SP isolates had MICs of 0.06 mg/L despite carrying fusC. CHX MICs did not correlate with qacA/B (n = 2) and smr (n = 5), which were found in SEUK SA, and SP from NUK and U.S.A. CONCLUSIONS: Increased FA MICs were frequently associated with fusA mutations and fusC, and this is the first account of fusB in SP. Despite novel description of qacA/B in SP, gene presence did not correlate with CHX MIC. Selection pressure from clinical use might increase prevalence of these genetic determinants, but clinical significance remains uncertain in relation to high skin concentrations achieved by topical therapy.

Analysis of medium-range order based on simulated segmented ring detector STEM-images: amorphous Si.

Properties of amorphous materials are connected to the local structure at the nanoscale, which is typically described in terms of short- and medium-range order (SRO, MRO). Variable resolution fluctuation electron microscopy (VR-FEM) is a sensitive method to characterize the underlying characteristic length scale of MRO of amorphous samples (Voyles, Gibson and Treacy, J. Electron Microsc. 49 (2000) 259). VR-FEM data was acquired using scanning transmission electron microscopy (STEM), collecting a large number of nano-beam diffraction patterns (NBDPs) with various probe sizes. Here we present an advanced method to accelerate the calculation of simulated FEM normalized variance profiles using a newly developed simulation and analysis approach with segmented ring detectors using the program STEMcl (Radek et al., Ultramicroscopy 188 (2018) 24). VR-FEM simulations are based on structures obtained from molecular dynamics (MD) simulations. A comparison between simulated and experimental VR-FEM profiles with respect to peak position, ratio and shape (and intensity) show good agreement. Moreover, a crystalline cluster of 1 nm in size was embedded into the MD box to test the validity of the paracrystalline approximation with the pair-persistence analysis suggested by Gibson et al. (Gibson, Treacy and Voyles, Ultramicroscopy 83 (2000) 169). The corresponding VR-FEM simulation and calculation of MROs yield close results to the size of the initially embedded crystalline cluster, which supports both the paracrystalline approach and the validity of the segmented detector simulation. Additionally, we conclude that continuous random network (CRN) amorphous silicon models contain a higher degree of MRO than experimentally expected.

[Microinvasive glaucoma surgery-Efficacy of trabecular stents in combined interventions : A clinical study on 65 eyes]. / Mikroinvasive Glaukomchirurgie ­ Wirksamkeit von trabekulären Stents bei kombinierten Eingriffen : Eine klinische Studie an 65 Augen.

BACKGROUND AND OBJECTIVE: In this prospective randomized simple blind study, we investigated the long-term results of trabecular micro-bypass stent implantation as part of routine cataract surgery in eyes with primary chronic open-angle glaucoma. The chamber angle implants drain between the anterior chamber and the canal of Schlemm and circumvent the main outflow resistance by the trabecular meshwork. PATIENTS AND METHODS: The study included 65 eyes from 56 patients with primary chronic open-angle glaucoma with at least 2 different pressure-lowering drugs. Patients with low-tension glaucoma, secondary glaucoma and ocular hypertension were excluded. Of the 65 eyes 31 underwent a combined cataract surgery with subsequent implantation of 2 iStents inject GTS-400 (Glaukos Corporation, San Clemente, CA, USA) into the canal of Schlemm. In the same time period 34 of the 65 eyes underwent standard cataract surgery without stent implantation. RESULTS: The longest follow-up time was 38 months and the mean follow-up time was 14 months. In our follow-up observational study the average intraocular pressure (IOP) reduction with combined surgery was 5.9 mm Hg or 23.5% of the original value (p < 0.001). The extent of IOP reduction depended on the level of the preoperative pressure. CONCLUSION: The combined phacoemulsification and trabecular micro-bypass implantation was shown to be an effective and safe treatment method for reduction of IOP and the burden of local administration of medication could be reduced. The implantation provides a good option for additional reduction of IOP. Our results showed a favorable risk-benefit profile. Further long-term in vivo studies are needed to determine the long-term safety and efficacy.

Analysis of the 3D microstructure of experimental cathode films for lithium-ion batteries under increasing compaction.

It is well known that the microstructure of electrodes in lithium-ion batteries has an immense impact on their overall performance. The compaction load during the calendering process mainly determines the resulting morphology of the electrode. Therefore, NCM-based cathode films from uncompacted (0 MPa) to most highly compacted (1000 MPa) were manufactured, which corresponds to global porosities ranging from about 50% to 18%. All samples have been imaged using synchrotron tomography. These image data allow an extensive analysis of the 3D cathode microstructure with respect to increasing compaction. In addition, the numerous microstructural changes can be quantified using several characteristics describing the morphology of cathode samples. Three characteristics, namely global porosity, global volume fraction of active material and mean cathode thickness, are compared to experimental results. In addition, the microstructural analysis by means of 3D image data and image processing techniques allows the investigation of characteristics which are hard or impossible to ascertain by experiments, for example the continuous pore size distribution and the sphericity distribution of NCM-particles. Finally, the dependency of microstructural characteristics on compaction load is described by the help of parametric probability distributions. This approach can be used, for example, to predict the distribution of a certain characteristic for an 'unknown' compaction load, which is a valuable information with regard to the optimization and development process of NCM-cathodes in lithium-ion batteries. LAY DESCRIPTION: It is well known that the microstructure of electrodes in lithium-ion batteries has an immense impact on their overall performance. The manufacturing of the batteries includes the so-called calendering, where the electrodes are compressed with a certain pressure, which is called compaction load. This process step mainly determines the resulting morphology of the electrode and thus the properties of the battery. Therefore, eight cathodes with different compaction loads were manufactured and imaged by synchrotron tomography, which leads to 3D images containing detailed information about the inner structure of the cathode. This image data allows an extensive analysis of the 3D cathode microstructure with respect to increasing compaction. In order to quantify the microstructural changes we use several characteristics describing diverse properties of the morphology. Furthermore, the 3D image data can be used for the computation of characteristics which can not be determined by experiments. Therefore, 3D image data allows us to understand how the microstructure of cathodes is influenced by the compaction load. Finally, we are able to predict the distribution of a certain characteristic for arbitrary compaction loads. This information is valuable with regard to the development of improved lithium-ion batteries.

Pore space extraction and characterization of sack paper using µ-CT.

We show that attenuation X-ray microcomputed tomography (µ-CT) offers a route to extract the three-dimensional pore space of paper reliably enough to distinguish samples of the same kind of paper. Here, we consider two sack kraft papers for cement bags with different basis weights and thicknesses. Sample areas of approximately 5 mm2 with a resolution of 1.5 µm are considered, i.e. sizes that exceed sample areas of 2 mm2 for which the pore structure was previously studied in the literature. The image segmentation is based on indicator kriging as a local method that removes ambiguities in assigning voxels as pore or as fibre. The microstructures of the two samples are statistically compared in terms of descriptors such as sheet thickness, porosity, fractions of externally accessible pores and mean geodesic tortuosity. We demonstrate that a quantitative comparison of samples in terms of porosity and thickness requires a common definition of the sheet surfaces. Finally, the statistical pore space analysis based on the µ-CT scans reliably reveals structural differences between the two paper samples, but only when several descriptors are used. LAY DESCRIPTION: This paper is a seemingly abundant material. Its intrinsic porosity enables a vast number of commercial applications. Particularly packing products, e.g. cement bags, often incorporate sack kraft paper due to its high porosity and its additional mechanical strength. A direct quantification of the porosity of sack kraft papers is, hence, particularly desirable. However, experimental quantification of paper porosity or its pore network properties is difficult and often highly indirect. A nondestructive statistical analysis of the 3D microstructure holds the promise to directly assess the pores. In particular, X-ray microcomputed tomography (µ-CT), frequently with sub-µm resolution, has been established as a method to study the fibre and pore structure of paper. The question arises, whether statistical analysis of the microstructure based on µ-CT imaging is sufficient to reliably distinguish between different sack kraft papers. Here, we explore whether the pore structure of paper can be extracted and statistically analysed for larger sample areas despite the fact that a larger sample size directly translates into a lower resolution of the µ-CT scan. We expect that a large sample size increases the region of interest on the basis of which samples can be better distinguished. A lowered resolution poses a severe challenge for the reliable identification of voxel data as pores or as fibres, because the contrast between paper fibres (made of cellulose) and air, which is established due to X-ray absorption, is weak. We show that we can reliably assign each voxel by using an indicator kriging as a two-step method. This method performs an initial voxel identification based on the overall distribution of measured grey values and refines the identification by inspecting the local environment of each voxel. For the pore space extracted in such a way, we can then compute quantities that are related to the geometry and connectivity properties of the pores. Furthermore, we address a paper-born challenge for such an analysis, i.e. we cannot always unambiguously tell whether a pore is located inside the paper sheet or at the surface of the paper. The way the paper surfaces are extracted from the microstructure decisively determines the final specifications of the predicted properties. A significant distinction of the samples is only possible when comparing the properties of the pore network.