bluuebunny/crossref_metadata_2025 huggingface dataset:
Outcomes among pregnant recently incarcerated women attending a reentry transitions clinic
Authors: Morse Diane S. , Wilson John L. , Driffill Nicole J. , Lauture Joloire , Khan Ali , King‐Turner Stella O.
Published: December 2018

This mixed methods retrospective case series and qualitative descriptive study describes pregnancy outcomes during the postincarceration period. A retrospective case series via electronic medical record chart review from a subset of women attending a postincarceration primary care clinic with a condition of interest (pregnancy) described demographics, substance use, diagnoses, and pregnancy outcomes. We compared 27 pregnant to 79 nonpregnant women and contextualized quantitative data with qualitative descriptive vignettes. Twenty‐seven women completed 29 pregnancies (2 women with 2 deliveries each), all of which were unplanned; there were 11 live births, 8 pregnant at study closure, 7 miscarriages, and 3 terminations. Although substance use history was high, rates were higher among nonpregnant women (92% vs 74%). Among the 5 births, 4 tested positive for substance use during pregnancy. All 11 infants had pregnancy or delivery complications. Although 7 of the 10 pregnant women with live births had prior pregnancy complications, only 4 were placed in a special care obstetrics clinic. Although unplanned pregnancies were common, most births did not demonstrate maternal substance use. All live births had pregnancy or delivery complications, but few were accepted to specialist prenatal care, suggesting potential considerations for recently incarcerated women.
Systemic Tofacitinib Concentrations in Adult Patients With Atopic Dermatitis Treated With 2% Tofacitinib Ointment and Application to Pediatric Study Planning
Authors: Purohit Vivek S. , Ports William C. , Wang Cunshan , Riley Steve
Published: December 2018

Atopic dermatitis is a chronic eczematous, pruritic, inflammatory skin condition affecting children and adults. Tofacitinib is a Janus kinase inhibitor. The efficacy, safety, and pharmacokinetics of 2% tofacitinib ointment twice daily have been evaluated in a 4‐week phase 2a multisite randomized, double‐blind, vehicle‐controlled, parallel‐group study (NCT02001181) in adult patients with mild to moderate atopic dermatitis and 2% to 20% body surface area (BSA) involvement. Tofacitinib ointment demonstrated significantly greater efficacy versus vehicle for all efficacy end points and had an acceptable safety profile. Predose and postdose pharmacokinetic samples were collected in week 2 and week 4. The objective of this analysis was to assess if predicted mean tofacitinib concentrations with topical application at higher treated BSA across age groups would exceed relevant concentration thresholds based on oral doses of tofacitinib. In this analysis, the pharmacokinetic concentrations were characterized using a linear mixed‐effects model. The model was used to predict concentrations for adults with higher (>20%) treatable BSA. Adult concentrations were used to extrapolate concentrations to a pediatric population (2 to 17 years) using allometric principles. The predicted systemic concentrations for 2% tofacitinib ointment in both adult and pediatric populations at treated BSA ≤50% for a mild to moderate atopic dermatitis population did not exceed those reported for the 10th percentile of observed oral tofacitinib 5‐mg twice‐daily doses in patients with moderate to severe plaque psoriasis. The methodology described will enable analysis and prediction of systemic concentrations for topical agents.
A Review of Consumer Embarrassment as a Public and Private Emotion
Authors: Krishna Aradhna , Herd Kelly B. , Aydınoğlu Nilüfer Z.
Published: December 2018

Whether the result of mispronouncing a fancy brand name, miscalculating a tip, purchasing a sensitive product, or stumbling into a product display, embarrassment is an important part of the consumer landscape. Embarrassment has traditionally been considered a social emotion, one that can only be experienced in public. In this paper, we offer a comprehensive review of consumer embarrassment and consider situations in which embarrassment can affect consumer behavior in both public and private contexts. We define embarrassment using this broader conceptualization and outline the transgressions that might trigger embarrassment in consumption contexts. We also discuss the diverse implications of embarrassment for consumer behavior, and review the strategies that both consumers and practitioners can use to mitigate embarrassment and its negative consequences. We hope this framework will stimulate new research on consumer embarrassment in both public and private contexts.
An LDHa single allele CHO cell mutant exhibits altered metabolic state and enhanced culture performance
Authors: Wilkens Camila A , Vishwanathan Nandita , Baltes Nicholas J , Lucero Alicia T , Hu Wei‐Shou , Gerdtzen Ziomara P
Published: December 2018

BACKGROUND

Reducing lactate production in animal cell cultures has been reported to improve cell culture performance and productivity of recombinant protein. A novel genome editing tool, CRISPR/Cas, has been used widely to induce double‐strand breaks in the genome and introduce targeted mutations efficiently.

RESULTS

In the present work, we used a publicly available human‐codon optimized CRISPR/Cas system to introduce mutations in one of the LDHa gene copies to obtain an LDHa single‐allele knockout Chinese hamster ovary (CHO) cell clone to analyze its effect over cell metabolism. Fed‐batch cultures were conducted in order to evaluate the culture performance of mutant cells. Results show that cell growth was reduced and metabolism was modified by the LDHa single‐allele knockout, whereas specific protein rate and volumetric production were greatly enhanced. Additionally, the first in‐depth analysis of the metabolic effects of LDHa single allele knockout is presented.

CONCLUSION

By using CRISPR/Cas we were able to knock down LDHa, showing improved culture productivity. Metabolic flux analysis revealed higher fluxes in the TCA cycle in the mutant cell than in the parental cell, indicating that LDHa mutant cells have an enhanced energy metabolism, which can be attributed mainly to a higher catabolism of amino acids. © 2018 Society of Chemical Industry
Supercritical fluid extraction for enhancing polyphenolic compounds production from olive waste extracts
Authors: Caballero Ashley S , Romero‐García Juan M , Castro Eulogio , Cardona Carlos A
Published: December 2018

BACKGROUND

A number of residues are produced during the olive oil extraction process, such as crushed pits, olive leaves, pomace and exhaust olive pomace. In addition, pruning of olive trees results in a huge amount of biomass. All of these lignocellulosic materials constitute a source of energy and chemicals that can be used as raw materials in biorefineries. Among them, antioxidants are of particular interest due to their potential applications in pharmaceutical and food industry.

RESULTS

Supercritical fluid extraction (SFE) was applied on three different olive residues – pruning biomass, leaves and exhaust pomace. In this, 60% ethanol was used as cosolvent at three different pressure levels, 200, 250 and 300 bar. The best conditions for each residue were determined and compared with conventional extraction. Results show that 300 bar was the best pressure for SFE in terms of antioxidant activity of the extracts. The main polyphenolic compounds also were identified, among which hydroxytyrosol, chlorogenic acid, caffeic acid and ferulic acid were present.

CONCLUSION

SFE at 300 bar proved to be the best option for obtaining a high‐activity antioxidant extract from olive leaves, exhaust pomace and pruning biomass, with hydroxytyrosol the prominent compound detected. This procedure could be integrated in a biorefinery based on olive‐derived biomass. © 2018 Society of Chemical Industry
Unanticipated Heterocyclization from Reaction of Hydrazine Hydrate and/or Hydrazine Dihydrochloride with 1‐Ethyl‐4‐hydroxyquinolin‐2(1H)‐one
Authors: Hassan Heba
Published: December 2018

Unexpectedly, the reaction of 1‐ethyl‐4‐hydroxyquinolin‐2(1H)‐one (1) with hydrazine hydrate and/or hydrazine dihydrochloride led to three different products. In addition to the expected quninolinylhydrazine, two heteropentacycles, diquinopyrrole and diquinopyridazine, were afforded, depending on reaction conditions. The structure of the new products was established upon their spectral and analytical data.
Embryogenesis and early larval development in wild‐caught Levantine scraper,Capoeta damascina(Valenciennes, 1842)
Authors: Zadmajid Vahid , Sørensen Sune Riis , Butts Ian Anthony Ernest
Published: December 2018

Levantine scraper,Capoeta damascinais a candidate species for future stock assessments, conservation studies, and hatchery efforts. Herein, we documented embryonic and early larval development, from egg activation to the exogenous feeding period, using morphological and histological landmarks. Embryos were obtained by in vitro fertilization from hormonally induced wild‐caught broodstock, and subsequent development was monitored at temperatures coinciding with native conditions. Embryonic development from fertilization to hatch lasted ~105–110 hr. Larvae emerged with unpigmented eyes and body morphology, as well as an undifferentiated digestive tract. The mouth was closed at hatch by the oropharyngeal membrane and opened by the early endogenous feeding period. Trabeculae cartilage, quadrate bone, and Meckel's cartilage of the endoskeleton were present during the endogenous feeding period. During this period, the larvae underwent considerable changes in craniofacial morphology, locomotion, and organogenesis of the digestive tract. The cartilaginous floor of the neurocranium developed and the first four ceratobranchials appeared simultaneously at the end of endogenous feeding period. The digestive tract was differentiated into buccopharynx, esophagus, and small intestine during the endogenous feeding period. The intestinal valve and numerous longitudinal folds at the posterior region of the intestine formed together by the endo–exogenous feeding period. Major developmental events in retinogenesis occurred during the endogenous feeding period. When larvae entered exogenous feeding the mouth was fully‐functional. Additionally, liver size and eye diameter increased. Our analysis of embryonic and early larval development in Levantine scraper aligned with other freshwater fishes.
Increased perfusion in dynamic gadolinium‐enhanced MRI correlates with areas of bone repair and of bone necrosis in patients with Kienböck's disease
Authors: Müller Gunilla , Månsson Sven , Müller Markus F. , Johansson Martin , Björkman Anders
Published: December 2018

Background

Osteonecrosis of the lunate, Kienböck's disease, can lead to fragmentation of the lunate, carpal collapse, and severe osteoarthritis. Since the etiology of Kienböck's disease is impaired circulation, a diagnostic method capable of assessing perfusion would be valuable. Recent studies have suggested that dynamic contrast‐enhanced (DCE) MR examinations at 3 T can assess perfusion in healthy carpal bones.

Purpose

To evaluate the use of DCE‐MR for assessing perfusion in the lunate bone in patients with Kienböck's disease. Furthermore, to compare perfusion with histopathology with a focus on bone viability.

Study Type

Prospective case–control study.

Population

Fourteen patients with Kienböck's disease and a control group of 19 healthy subjects.

Field Strength: 3 T with T1‐weighted fat‐saturated contrast‐enhanced gradient echo series.

Assessment

Features of the enhancement curves from the DCE‐MR examinations, time to peak (TTP), maximum slope (MS), and maximum enhancement (ME) assessed by a radiologist. Six of 14 patients were surgerized with lunate excision, allowing comparison between features of the enhancement curves and histopathology.

Statistical Tests

Mann–Whitney U‐test. P < 0.05 was considered a statistically significant difference.

Results

Patients with Kienböck's disease showed significantly higher and faster perfusion parameters compared with the control group, the mean value of the TTP in patients was 126.73 sec, in controls 189.79 sec (P = 0.024), ME in patients 173.55 AU, in controls 28.46 AU (P < 0.001), and MS in patients 5.04 AU, in controls 1.06 AU (P < 0.001). When compared with histopathology, increased perfusion was seen in areas of bone formation but also in necrosis. Areas of normal bone showed low perfusion.

Data Conclusion

DCE‐MRI at 3 T can diagnose altered perfusion in patients with Kienböck's disease. Increased perfusion cannot definitely be used as a marker of bone viability.

Level of Evidence: 1

Technical Efficacy: Stage 3

J. Magn. Reson. Imaging 2019;50:481–489.
Direct and indirect effects of CO2increase on crop yield in West Africa
Authors: Sultan Benjamin , Parkes Ben , Gaetani Marco
Published: December 2018

Climate change directly threatens food security in West Africa through a negative impact on productivity of the main staple food crops. However, providing consistent future crop yield projections in the region remains challenging because of uncertainty in the response of the regional climate to the CO2increase and in the response of the cultivated crop to this altered climate with more CO2in the atmosphere. Here, we analyse a set of idealized climate simulations to investigate the effect of CO2concentration increase on the West African monsoon and potential impacts on crop yields of maize. On the one hand, simulations with prescribed SST and quadrupled CO2concentration are analysed to study the atmospheric response to direct radiative forcing induced by increasing CO2concentration, not mediated by ocean heat capacity. On the other hand, simulations with prescribed SST augmented by 4 K are analysed to study the atmospheric response to the global ocean warming expected as a consequence of the increasing CO2radiative forcing. We show that if CO2concentration increase has a positive impact on crop yield due to the fertilization effect, it also has a direct effect on the monsoon which acts to increase (decrease) rainfall in the eastern (western) part of the Sahel and increase (decrease) crop yields consequently. Finally, we show that SST warming acts to reduce rainfall and increase local temperatures leading to strong reduction of crop yield. The reduction of crop yield is more important in the eastern part of the Sahel where the warming is more intense than in the western part of the Sahel. Overall, positive effects are weaker and more uncertain than the negative effects in the analysed simulations.
TNF‐α enhances apoptosis by promoting chop expression in nucleus pulposus cells: role of the MAPK and NF‐κB pathways
Authors: Zhang Jian , Wang Xiaolin , Liu Hui , Li Zemin , Chen Fan , Wang Hua , Zheng Zhaomin , Wang Jianru
Published: December 2018

CHOP has been shown to be involved in AF cells apoptosis and disc degeneration in a rat model. The aim of this study was to investigate the regulatory effects of TNF‐α on C/EBP homologous protein (CHOP) and the role of CHOP in nucleus pulposus (NP) cell apoptosis. The effects of TNF‐α on chop were measured by qPCR, Western blot, and immunofluorescence. TNF receptor involvement was analyzed by small interfering RNA (siRNA), Western blotting, immunofluorescence, and qPCR. The effects of NF‐κB and MAPK on TNF‐α‐mediated chop promoter activity were studied using siRNAs, Western blotting, immunofluorescence, and qPCR. The regulatory effects of TNF‐α‐induced CHOP on Bcl‐2 and Bax were studied using siRNAs, Western blotting, immunofluorescence, and qPCR. Flow cytometric and TUNEL analyses were performed to investigate the effects of chop on NP cell apoptosis. Increased CHOP expression was observed in NP cells after TNF‐α treatment. Treatment of cells with TNF receptor, NF‐κB, and ERK/JNK‐MAPK inhibitors or siRNAs abolished the effects of cytokines on CHOP expression. Pharmacological siRNA knockdown of chop promoted Bax, decreased Bcl‐2, and attenuated TNF‐α‐mediated cell apoptosis. During intervertebral disc degeneration (IVDD), TNF‐α binds to TNF receptors and controls the JNK/ERK‐MAPK, and NF‐κB signaling pathways in NP cells, increasing CHOP expression. This change up‐regulates the pro‐apoptotic protein Bax and down‐regulates the anti‐apoptosis protein Bcl‐2, inducing cell apoptosis. This study suggests a potential therapeutic target for controlling the inflammatory‐induced apoptosis associated with IVDD. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res
Determination of acidic drugs in biological and environmental matrices by membrane‐based dual emulsification liquid‐phase microextraction followed by high‐performance liquid chromatography
Authors: Moradi Peyman , Asghari Alireza
Published: December 2018

A simple method is introduced providing a highly clean microextraction for the determination of some anti‐inflammatory drugs as the model analytes in human urine and environmental matrices. This method is based upon the implementation of two consecutive emulsification liquid‐phase microextractions, which are separated by a syringe filtration step. In this method, the organic extraction solvent (dihexyl ether) is dispersed into the aqueous sample solution (20 mL), and the resulting cloudy mixture is passed through a hydrophilic polytetrafluoroethylene syringe filter. By this action, the extraction phase containing the analytes and many interfering species that could be transferred into the organic phase is retained behind the hydrophilic membrane. The filter is then detached from the syringe and attached to another syringe containing an aqueous solution (pH 12.0, 150 μL), and by the in‐syringe dispersion of the organic phase into the aqueous phase, the analytes are selectively back‐extracted into the aqueous phase. The developed method is centrifuge‐free and very simple, and provides a high sample clean‐up in a few minutes. Under the optimized experimental conditions, the developed method provided a linearity in the range of 2.0–2000 ng/mL, a low limit of detection (0.5 ng/mL), and enrichment factors of 47–53.
Linc00161 regulated the drug resistance of ovarian cancer by sponging microRNA‐128 and modulating MAPK1
Authors: Xu Mei , Zhou Kai , Wu Yuanzhe , Wang Li , Lu Su
Published: December 2018

This study aimed to investigate the regulatory mechanism of linc00161/miR‐128/MAPK1 axis on drug resistance of ovarian cancer. Methods: the differentially expressed lncRNAs were screened based on microarray analysis. The expression of linc00161, miR‐128 and MAPK1 in ovarian cancer‐resistant tissues and cells was tested qRT‐PCR, whereas MAPK1 protein expression was examined via western blot in the ovarian cancer resistant cells. The targeted relationship between miR‐128 and linc00161 as well as the relationship between miR‐128 and MAPK1 were testified by Dual luciferase gene reporter assay. The influence of miR‐128 and MAPK1 on the proliferation of ovarian cancer‐resistant cells was demonstrated by CCK‐8 and colony formation assay. The effect of linc00161 on ovarian cancer was demonstrated by xenograft tumor model in vivo. Results: Linc00161 was highly expressed in ovarian cancer‐resistant tissues and SKOV3/DDP cells while the miR‐128 displayed a lower expression. Overexpression of linc00161 increased the colony formation ratio in SKOV3 cells, whereas sh‐linc00161 reduced colony formation ratio in SKOV3/DDP cells. MAPK1 was highly expressed in ovarian cancer‐resistant tissues and cells and could be regulated by linc00161 and miR‐128. The proliferation ability of SKOV3 cell was enhanced after transfected with miR‐128 inhibitor, whereas that of SKOV3/DDP cells was attenuated by miR‐128 mimics. In addition, the colony formation ratio of SKOV3 cells co‐transfected with DDP + MAPK1 + sh‐linc00161 decreased. The colony formation ratio of SKOV3/DDP cells also declined after transfected with DDP+ MAPK1. Linc00161 regulated the drug resistance of ovarian cancer via modulating microRNA‐128/MAPK1. In vivo, sh‐linc00161 inhibited the tumor growth.
The Effects of Dual‐Task Cognitive Interference and Environmental Challenges on Balance in Huntington's Disease
Authors: Purcell Nicollette L. , Goldman Jennifer G. , Ouyang Bichun , Bernard Bryan , O'Keefe Joan A.
Published: December 2018

Background

Huntington's disease (HD) is characterized by chorea, balance and gait impairments, and cognitive deficits, which increase fall risk. Dual task (DT) and environmentally challenging paradigms reflect balance related to everyday life. Furthermore, the impact of cognitive deficits on balance dysfunction and falls in HD is unknown.

Objective

To determine the impact of DT interference, sensory feedback, and cognitive performance on balance and falls in HD.

Methods

Seventeen participants with HD (55 ± 9.7 years) and 17 age‐matched controls (56.5 ± 9.3 years) underwent quantitative balance testing with APDM inertial sensors. Postural sway was assessed during conditions of manipulated stance, vision, proprioception, and cognitive demand. The DT was a concurrent verbal fluency task. Neuropsychological assessments testing multiple cognitive domains were also administered.

Results

HD participants exhibited significantly greater total sway area, jerk, and variability under single‐task (ST) and DT conditions compared to controls (P = 0.0002 – < 0.0001). They also demonstrated greater DT interference with vision removed for total sway area (P = 0.01) and variability (P = 0.02). Significantly worse postural control was observed in HD with vision removed and reduced proprioception (P = 0.001 – 0.01). Decreased visuospatial performance correlated with greater total sway and jerk (P = 0.01; 0.009). No balance parameters correlated with retrospective falls in HD.

Conclusions

HD participants have worse postural control under DT, limited proprioception/vision, and greater DT interference with a narrowed base and no visual input. These findings may have implications for designing motor and cognitive strategies to improve balance in HD.
The biomarker potential of cell‐free microRNA from cerebrospinal fluid in Parkinsonian Syndromes
Authors: Starhof Charlotte , Hejl Anne‐Mette , Heegaard Niels H.H. , Carlsen Anting L. , Burton Mark , Lilje Berit , Winge Kristian
Published: December 2018

Background: MicroRNAs are small noncoding RNAs involved in the post‐transcriptional regulation of protein synthesis. Extracellular microRNAs are accessible in a stable form in biofluids.

Objectives: The aim was to identify individual microRNAs and/or subsets of microRNAs in CSF with biomarker potential and thus identify specific putative pathophysiological pathways.

Methods: In a two‐step exploratory study design of PD, MSA, PSP, and controls, we initially profiled CSF microRNAs in a pilot cohort (n = 40) by screening for 372 microRNAs. Subsequently, we attempted to validate findings in an independent study cohort in CSF (n = 118) and ethylenediaminetetraacetic acid plasma (n = 114). This study cohort encompassed 46 microRNAs, of which 26 were singled out from the pilot cohort, and an additional 20 microRNAs were added based on previous publications. The most accurate diagnostic microRNA classifiers were identified in a multivariable logistic regression model adjusted for age and sex.

Results: A set of three microRNAs in CSF discriminated PD and MSA from controls with good diagnostic accuracy by receiver operating characteristics curve evaluation. The microRNAs were for PD versus controls: miR‐7‐5p, miR‐331‐5p, and miR‐145‐5p (area under the curve = 0.88) and MSA versus controls: miR‐7‐5p, miR‐34c‐3p, and miR‐let‐7b‐5p (area under the curve = 0.87). The classifier that best distinguished MSA and PD consisted of two microRNAs: miR‐9‐3p and miR‐106b‐5p (area under the curve = 0.73). A single microRNA, miR‐106b‐5p, provided the best discrimination between PD and PSP (area under the curve = 0.85) in the CSF.

Conclusions: Levels of specific trios of CSF‐microRNAs discriminate well between α‐synucleinopathies (PD and MSA) and controls. The results need to be validated in larger, independent cohorts. © 2018 International Parkinson and Movement Disorder Society
The Early Life History of the Guadalupe Bass: Lessons for Culturing a Threatened Species
Authors: Prangnell David I , Matthews Michael D
Published: December 2018

Guadalupe Bass Micropterus treculii fingerlings are produced at the A. E. Wood State Fish Hatchery in San Marcos, Texas, and stocked into streams draining the Edwards Plateau in central Texas as part of a conservation program to restore threatened populations and combat hybridization with Smallmouth Bass M. dolomieu. Despite an intensive conservation effort, much of the early life history (including morphological development and first feeding characteristics) required for the intensive production of Guadalupe Bass is unreported in the mainstream literature. A better understanding of this critical period may improve culture practices, fingerling production, and management efforts. We documented spawning and early developmental characteristics and milestones over a temperature range of 20–24°C and the prey composition of Guadalupe Bass in a hatchery setting. Eggs and fry were photographed under a microscope and observed in culture tanks and ponds from initial stocking to fingerling harvest. A dominant-male, polygynous spawning structure was confirmed. Egg incubation (28–29 growing degree-days), larval development, yolk depletion, swim-up, and life stage transition proceeded faster at higher temperature. Eggs (mean diameter, 2.1 mm), fry (mean hatchling TL, 4.7 mm), and yolk reserves (mean hatchling yolk volume, 2.02 μL) were larger than reported for Largemouth Bass M. salmoides. Normally developed fry commenced exogenous feeding on a variety of zooplankton soon after swim-up (120–144 h posthatch and 6.95–8.05 mm TL at 23.4°C), while yolk was still present, and consumed progressively larger aquatic invertebrates over time. Swim-up fry with a range in gape width of 0.75–0.89 mm readily consumed brine shrimp Artemia spp. nauplii as first feed. Guadalupe Bass appear to be a relatively pliable species, and current culture practices are generally sound. The observations presented can be used to refine culture and management practices.
A Crank–Nicolson collocation spectral method for the two‐dimensional viscoelastic wave equation
Authors: Jin Shiju , Luo Zhendong
Published: December 2018

In this paper, we first establish the Crank–Nicolson collocation spectral (CNCS) method for two‐dimensional (2D) viscoelastic wave equation by means of the Chebyshev polynomials. And then, we analyze the existence, uniqueness, stability, and convergence of the CNCS solutions. Finally, we use some numerical experiments to verify the correctness of theoretical analysis. This implies that the CNCS model is very effective for solving the 2D viscoelastic wave equations.
Lightweight construction with two‐dimensional cellular solids in additive manufacturing
Authors: Großmann Alexander , Mittelstedt Christian
Published: December 2018

Additive manufacturing delivers a high degree of manufacturing freedom. New applications such as structural integration of cellular structures are enabled by this technology. However, the manufacturing process bears some challenges, that need to be investigated. This contribution focusses on manufacturing, elastic properties and lightweight degree assessment of two dimensional cellular solids. To get a high lightweight degree at a given stiffness one must be aware of the structure's geometry and the amount of material used in a representative volume element. Even though this can be obtained by simple geometric considerations little research has been conducted on that aspect.

In this work we deliver exact solutions for the so called relative density, which denotes the volume fraction of material used in a representative volume element, which is crucial to assess the lightweight degree. Furthermore an approach in order to realize the corresponding structures by a powder bed based additive manufacturing process will be presented.
Fiber‐based modeling of muscles in the musculoskeletal system
Authors: Gfrerer Michael , Simeon Bernd
Published: December 2018

The aim of this contribution is to present a fiber‐based modeling approach for the behavior of muscles within the musculoskeletal system. We represent the skeletal system as a rigid multibody system which is actuated by muscles. Each muscle is represented by one 1D cable with variable cross section undergoing large deformation and strains. We employ a incompressible Kelvin‐Voigt material for the passive behavior and a active stress law found in the literature. We incorporate contact between the muscles and the rigid bodies within a finite element framework by the penalty method. We apply our framework to conduct a forward simulation of a simple upper limb model.
Complex Falk‐Langemeyer Method
Authors: Hari Vjeran
Published: December 2018

The known Falk‐Langemeyer method for the simultaneous diagonalization of two positive definite symmetric matrices is generalized to work with complex matrices. It is shown that the derived method is well defined for the Hermitian matrices which make a definite pair. Special attention is paid to the stability of the formulas for the computational parameters when the pivot submatrices are close to being proportional. Numerical tests indicate the high relative accuracy of the method provided that both matrices are definite and well‐behaved, i.e. if they can be well‐scaled symmetrically.
Impact of particle boundary conditions on the collision rates of inclusions around a single bubble rising in liquid metal
Authors: May Ronja , Gruy Frédéric , Fröhlich Jochen
Published: December 2018

In the presented flow simulations a spherical argon gas bubble rises in stagnant liquid metal with initially homogeneously distributed spherical aluminium oxide particles of small inertia. Depending on their relative position to the bubble particles are subjected to different fluid forces and show different collision behaviour. The contribution presents Direct Numerical Simulations with the bubble being geometrically resolved and the inclusions represented as point particles. In the community, the boundary condition at the particle surface is discussed controversially. To elucidate its potential influence, two extreme cases are simulated, one with full no‐slip condition, the other one with full slip condition. It is found that the influence of this change on the result is very small.
Homogenized material properties for cross‐laminated timber
Authors: Furtmüller Thomas , Adam Christoph , Giger Benjamin
Published: December 2018

In this contribution the coefficients of the elastic stiffness tensor of a generalized shell section for cross‐laminated timber (CLT) slabs are derived by application of a numerical homogenization scheme based on a repeating unit cell (RUC). In an example it is shown that a finite shell element model with those homogenized shell stiffness parameters predicts closely the modal properties of a CLT slab, thus, verifying the accuracy of the applied homogenization procedure for this type of structural members.
Energy‐momentum consistent time integration scheme for non‐linear electro‐elastodynamics
Authors: Janz Alexander , Betsch Peter , Franke Marlon , Ortigosa Rogelio
Published: December 2018

In this work we present a new approach to the design of energy‐momentum (EM) consistent algorithms inspired by the structure of polyconvex internal energy functions (see [1]) and tailor‐made for the consistent space‐time discretization of electro‐active polymers (EAPs). A Hu‐Washizu‐type mixed variational framework with a novel cascade form of kinematic constraints [2] along with the concept of partitioned discrete derivatives leads to a structure‐preserving time integrator, which shows superior numerical stability and robustness. This work can be seen as an extension of [1] to mixed formulations in the sense of [2].
Gradient‐Enhancement of a Rock Model Applied to Numerical Simulations of Tunnel Advance
Authors: Schreter Magdalena , Neuner Matthias , Hofstetter Günter
Published: December 2018

Rock is classified as a frictional cohesive material characterized by nonlinear stress‐strain relations including softening leading to structural failure. To describe the mechanical behavior of rock comprising the accumulation of irreversible strains, strain hardening, and the degradation of stiffness and strength, an isotropic damage plasticity model for intact rock and rock mass was proposed in [1]. In the context of numerical simulations of tunneling, considering strain softening of rock allows to predict the formation of shear bands emanating from the tunnel surface due to the excavation process, which is crucial for engineers to forecast potentially dangerous situations related to failure. To ensure objective results in the softening regime upon mesh refinement, in the aforementioned rock model the concept of the crack band approach by Bažant and Oh was adopted. As a remedy of known deficiencies related to this regularization approach, the rock model is extended by the over‐nonlocal implicit gradient‐enhancement proposed in [2]. Accordingly, a nonlocal field of the damage‐driving variable, implicitly defined as the solution of a Helmholtz‐like partial differential equation, is introduced yielding a fully coupled system of second‐order PDEs. In the present contribution, the over‐nonlocal gradient enhancement of the rock model is presented and applied together with a linear‐elastic material model for shotcrete to finite element simulations of a deep tunnel constructed by the New Austrian Tunneling Method. Based on this real example, objectivity of the results with respect to the finite element discretization is discussed.
Some remarks on parametric excitation in circulatory systems
Authors: Karev Artem , DeBroeck Lara , Hagedorn Peter
Published: December 2018

Dynamical systems with time‐periodic coefficients, i.e. with parametric excitation, have been studied in different fields for over a hundred years. It is well known that the presence of parametric excitation acts mostly destabilizing, leading to the emergence of instability regions depending on the amplitude and frequency of excitation. However, most of the work is done on systems with synchronous parametric excitation, while there are only few papers dealing with out‐of‐phase time‐periodicity. At the same time little to no research in this context is done on systems containing gyroscopic or circulatory terms. The present paper demonstrates different approaches for stability assessment of time‐periodic systems featuring nonconservative terms. In particular, out‐of‐phase parametric excitation as well as circulatory forces are considered in an example which is treated analytically and numerically. The derived stability boundaries show that the interaction of both features leads to the occurrence of rather unexpected resonance areas. The results extend the understanding of the influence of parametric excitation and encourage study of more general systems.
On anisotropy evolution in finite strain plasticity
Authors: Kaiser Tobias , Lu Jia , Menzel Andreas , Papadopoulos Panayiotis
Published: December 2018

Motivated by the experimental investigations on cold rolled sheet metal presented in [1], this contribution focuses on a specific modelling approach to capture the evolution of (plastic) material symmetry groups that is induced by finite plastic deformation processes. The ensuing developments are based on the general theoretical framework by Lu and Papadopoulos with regard to evolving material symmetries proposed in [2, 3]. In particular, we elaborate a specific form of the evolution equation for the structural tensor that characterises the respective material symmetry group and show that the simulation results are in good accordance with the experimental findings.
Willmore Flow of Networks
Authors: Garcke Harald , Menzel Julia , Pluda Alessandra
Published: December 2018

We consider networks of curves in the plane moving according to the L2 –gradient flow of the elastic energy. We prove short time existence in the case of networks composed of three curves that are required to meet at one or two triple junctions. As a variation of the result we additionally impose that they form angles of 120 degrees at the triple junction(s).
An energy based peridynamic state‐based failure criterion
Authors: Willberg Christian , Rädel Martin
Published: December 2018

The paper presents a verification and convergence study of an enhanced energy based failure model based on Foster et al. [2]. The failure model has been implemented in the open source software Peridigm. The study is performed with a virtual double cantilever beam test. To verify the implementation an energy release rate is virtually measured and compared with the input data. Time and load of the crack initiation are used as the convergence criteria.
Phase‐field modelling of fracture in heterogeneous materials
Authors: Hansen‐Dörr Arne C. , Gude Maik , Böhm Robert , Kästner Markus
Published: December 2018

In this contribution, we apply a phase‐field model to simulate fracture processes in heterogeneous materials. The local material structure is modelled in a diffuse manner, e.g. by a local reduction of the fracture toughness. In order to obtain a physically meaningful crack propagation, the interaction between the length scales of the diffuse microstructure and the regularised crack are studied. We employ a local correction of the fracture toughness assigned to the interface domain. The method is verified in several numerical benchmark problems and applied to simulate fracture processes in heterogeneous materials.
Optimal control of resources for species survival
Authors: Mazari Idriss , Nadin Grégoire , Privat Yannick
Published: December 2018

Consider a species whose population density solves the steady diffusive logistic equation in a heterogeneous environment modeled with the help of a spatially non constant coefficient standing for a resources distribution in a given box. We look at maximizing the total population size with respect to resources distribution, under some biologically relevant constraints. Assuming that the diffusion rate of the species is large enough, we prove that any optimal configuration is the characteristic function of a domain standing for the resources location. Moreover, we highlight that optimal configurations look concentrated whenever the diffusion rate is large enough. In the one‐dimensional case, this problem is deeply analyzed, and for large diffusion rates, all optimal configurations are exhibited.
Computation of the inf‐sup constant for the divergence
Authors: Gallistl Dietmar
Published: December 2018

A numerical method for approximating the inf‐sup constant of the divergence (LBB constant) is proposed, and some details of the convergence analysis are reported.
Comparative study of worm‐like chain models for collagen molecules
Authors: Hillgärtner Markus , Linka Kevin , Itskov Mikhail
Published: December 2018

Collagen is the main structural protein in various biological tissues and of high interest for microstructural multi‐scale models due to its load bearing functionality. The worm‐like chain (WLC) model [4] with its approximation [6] is a widely used approach for the modeling of DNA, which has a helical structure similar to tropocollagen. However, the classical WLC is suitable only for the entropic deformation regime of collagen. By modeling the extension behavior, it fails to give accurate predictions when the helical structure of the molecule starts twisting under higher loads.

The twistable worm‐like chain [3] and its special case referred to as the extensible worm‐like chain [7] aim to include the mechanical coupling between bond stretching and twist of the helix using a twist‐stretch coupling term, leading to more accurate predictions in the energetic regime. This contribution discusses different variations and coupling terms describing the molecular behavior behind the transition state between the entropic and energetic regime. Experimental data of the literature [1] are used to make a quantitative comparison of the discussed models and their applicability.
Efficient and reliable phase‐field simulation of brittle fracture using a nonsmooth multigrid solution scheme
Authors: Kienle Daniel , Gräser Carsten , Sander Oliver , Keip Marc‐André
Published: December 2018

In the last decades the phase‐field approach to fracture [1–3] has gained wide popularity due to advantages such as straight‐forward modeling of complex crack patterns and crack branching while allowing standard finite‐element discretizations. Time‐discrete phase‐field models of brittle fracture are typically formulated in terms of biconvex minimization problems for which a standard monolithic Newton‐Raphson scheme usually fails to converge. Solutions can be found by using operator‐splitting methods [2] or predictor‐corrector schemes [4]. Such methods come at the cost of high computational efforts. Furthermore, models incorporating the thermodynamically consistent local irreversibility of the damage phase‐field contain nonsmooth terms [2]. To improve the stability and to reduce the computational costs originating from the biconvexity and the nonsmoothness of the energy functional, we employ a nonsmooth multigrid method that can solve such problems roughly in the time of one equivalent linear problem [5] and which has been shown to be globally convergent [5]. We will demonstrate the computational speed of the proposed solution scheme by means of a classical benchmark problem of brittle fracture.
Efficient numerical simulations of drug delivery in multi‐component brain tissue
Authors: Wagner Arndt , Fink Davina , Ehlers Wolfgang
Published: December 2018

In this contribution, we discuss the problem‐specific application of suitable model‐reduction techniques to obtain an efficient numerical simulation of therapeutic infusion processes within multi‐component brain tissues. Therefore, the required set up is reviewed to apply the method of proper orthogonal decomposition (POD) in a combination with the discrete‐empirical‐interpolation method (DEIM) to a multi‐component brain‐tissue model based on the Theory of Porous Media (TPM). It appears that the required computation time for simulations can be reduced significantly. In this regard, an exemplary clinical issue (choice of the optimal infusion pressure) is discussed in terms of efficiency, accuracy, boundary‐value variations and clinical applicability.
Sensitivity Analysis of Nonlinear Structural Response regarding Geometry and External Loads
Authors: Liedmann Jan , Barthold Franz‐Joseph
Published: December 2018

This paper is concerned with response sensitivity analysis of elastoplastic structures regarding geometric shape and external load parameters. Additionally to classic shape optimization, sensitivity information has to be computed concerning external load parameters. Due to the path dependent material behavior, variations of history variables have to be provided likewise. The analytical derivation of sensitivities is based on an enhanced kinematic concept that allows a strict separation of physical and geometrical quantities. With this approach it is possible to compute the structural response and response sensitivity simultaneously within a finite element framework. The main base equations are briefly described and the accuracy of the algorithm is demonstrated in an academic example.
On an accurate and fast regularization approach to thermodynamic based topology optimization
Authors: Jantos Dustin Roman , Hackl Klaus , Junker Philipp
Published: December 2018

In our previous works [1–3], we introduced a variational approach derived from thermodynamical principles, i.e. Hamilton's principle for dissipative processes. The Hamilton principle directly yields evolution equations providing an iterative update scheme for the design variables of the problem, requiring no additional (mathematical) minimization algorithms.

We enhance our approach to reduce the calculation effort and improve the overall results: we introduce a regularization by penalizing the gradient of the density field, which gives us a well‐posed optimization problem. The strong form of the stationary condition results in a parabolic partial differential equation (PDE) which is solved by a finite difference method requiring minimal calculation effort. The regularization yields mesh‐independent results without checkerboarding. No additional filtering techniques are introduced and the complexity of the structure can be controlled a priori by a numerical parameter introduced along with the gradient penalization.
An efficient reduced computational method for nonlinear homogenization problems: the Hashin–Shtrikman type Finite Element method (HSFE)
Authors: Cavaliere Fabiola , Wulfinghoff Stephan , Reese Stefanie
Published: December 2018

This contribution is dedicated to a numerically efficient homogenization method for nonlinear microstructures (HSFE), which combines the small computational effort of the Hashin‐Shtrikman type approach with the accuracy of full‐field finite element solutions. The key point of the method is a model order reduction scheme based on data‐clustering, which leads to a significant reduction of computational time. The derivation of the analytical tangent operator realises the coupling between the microscopic and macroscopic scale. The presented approach is tested in the context of small strains by a numerical example, where a nonlinear RVE is attached to each integration point of a 2D macrostructure. A comparison to the FE‐simulations shows that the global‐ and local‐responses are well captured by the HSFE method.
Possibilistic and stochastic analysis using for rubber‐like materials
Authors: Penner Eduard , Caylak Ismail , Dridger Alex , Mahnken Rolf
Published: December 2018

In many engineering applications the material behavior, e.g. hyperelasticity, is described by an appropriate mathematical model. However, those become uncertain due to different types of uncertainty such as variation in the manufacturing process, measurement errors and missing or incomplete information on material properties. This contribution presents a framework for an uncertain nonlinear elastic material model at large deformations. As a key idea uncertainties of a material are described by correlated uncertain parameters, which are modeled in the first case as possibilistic and in the second case as random variables.
A finite element formulation in boundary representation for the analysis of nonlinear problems in solid mechanics
Authors: Klinkel Sven , Reichel Rainer
Published: December 2018

The contribution is concerned with a numerical element formulation for the analysis of the nonlinear behavior in solid mechanics. It is based on the so‐called scaled boundary finite element method (SB‐FEM). The SB‐FEM is as a semi‐analytical formulation to analyze problems of linear elasticity. The basic idea is to scale the boundary with respect to a scaling center. Hence, the boundary denoted as circumferential direction and the scaling direction span the parameter space. The original SB‐FEM approach is based on an analytical ansatz for the displacement response preserving equilibrium in scaling direction. In the present approach, an interpolation in scaling direction is introduced to account for nonlinear problems. Lagrange interpolations with different polynomial order are therefore discussed. The interpolation in circumferential direction is independent of the scaling direction and is defined by independent Lagrange functions. The displacement degrees of freedom are located at the nodes on the boundary and in the interior element domain. The degrees of freedom located in the interior of the domain are eliminated by static condensation, which leads to a polygonal finite element formulation with an arbitrary number of nodes on the boundary. The element formulation allows a priori for Voronoi meshes and quadtree mesh generation. Numerical examples give rise to the performance of the present approach in comparison to other element formulations, like mixed formulations.