bluuebunny/crossref_metadata_2025 huggingface dataset:
Dietary polyunsaturated fatty acids affect volume and metabolism of Drosophila melanogaster sperm
Authors: Guo Ruijian , Reinhardt Klaus
Published: January 2020

Dietary fatty acids can accumulate in sperm and affect their function in vertebrates. As Drosophila melanogaster shares several pathways of lipid metabolism and shows similar lipid‐dependent phenotypes but lacks some hormones that in vertebrates regulate lipid metabolism, there is currently no clear prediction as to how dietary fatty acids affect the sperm of D. melanogaster. We manipulated the amount and identity of dietary polyunsaturated fatty acids (PUFA) in the food of D. melanogaster males (a treatment known to affect membrane fluidity) and measured changes in sperm parameters. We found that (a) males reared on food containing PUFA‐rich, plant‐derived lipids showed a slower increase in sperm volume over male age compared to males reared on yeast‐derived lipid food which is richer in saturated fatty acids. (b) The resistance of sperm membrane integrity to osmotic stress was not altered by dietary lipid treatment, but (c) food containing yeast‐derived lipids induced a 46% higher in situ rate of production of reactive oxygen species in sperm cells. These findings show that dietary lipids have similar effects on sperm parameters in Drosophila as in vertebrates, affect some, but not all, sperm parameters and modulate male reproductive ageing. In concert with recent findings of sex‐specific seasonal variation of diet choice in the wild, our results suggest a substantial dietary impact on the dynamics of male reproduction in the wild.
In vitro human skin concentrations following topical application of 2% tranexamic acid in co‐enhancer cream and branded cream formulations
Authors: Ng Sue Phay , Marcant Mira , Davis Adrian Francis
Published: January 2020

Background

Melasma is a common pigmentary disorder that responds well to treatment with oral and/or locally injected tranexamic acid but less so to topical application. We hypothesized that this may be due to an inability of some topical formulations of tranexamic acid to achieve robust therapeutic concentrations at the viable epidermal target site in the skin.

Aims

To measure in vitro human epidermal and dermal skin concentrations of tranexamic acid following topical application of Fairence® T‐Complex, co‐enhancer cream and a Japanese branded cream control (“branded”) and compare these with estimates of tranexamic acid potency obtained from in vivo human pharmacokinetic and clinical studies and in vitro pharmacodynamic studies on inhibition of fibrinolysis.

Methods

Static vertical Franz cells and human abdominal skin were used to measure stratum corneum, viable epidermal, and dermal concentrations of tranexamic acid using HPLC‐MS‐MS analysis at 6 and 24 hour periods after topical application.

Results

Skin concentrations of tranexamic acid following application of the co‐enhancer cream were robustly within the concentration range estimated to be required for efficacy at both 6 and 24 hours. Those from the branded cream control were within the lower range at 24 hours.

Conclusions

These preclinical results support the benefits of conducting further studies, including a double‐blind placebo‐controlled clinical study, on Fairence® T‐Complex, co‐enhancer cream in patients with melasma. It is hypothesized that a more robust and timely clinical response may be achieved especially in refractory patients.
Analysis of risk factors of postlaparoscopic shoulder pain
Authors: Wada Shinichiro , Fukushi Yoshiyuki , Nishimura Mai , Matsumoto Sachiko , Takimoto Kanako , Imai Kazuaki , Ota Hajime , Tsuzuki Yoko , Nakajima Ayako , Fujino Takafumi
Published: January 2020

Aim

Postlaparoscopic shoulder pain (SP), mainly caused by pneumoperitoneum with CO2, sometimes suffers patients. This study was aimed to analyze the backgrounds of SP after gynecologic laparoscopy to clarify the risk of SP.

Methods

We analyzed answers of questionnaire about the degree of SP from 696 patients undergoing gynecologic laparoscopic surgery since 2014–2018. The questionnaire asks the degree of SP with numeric rating scale from 0 to 10, before and 3 days after operation. We defined cases in which postoperative score elevated more than three compared to preoperative score as SP(+). Analyzed backgrounds were age, parity, body mass index, operative method, operative duration and amount of hemorrhage. Statistics was performed by Fisher exact analysis as univariate analysis, and with logistic regression as multivariate analysis. All laparoscopic surgeries were performed under 10–12 mmHg in pressure of pneumoperitoneum with CO2.

Results

Univariate analysis revealed categories ‘less than 50 years old’, and ‘over 2 h’ and ‘over 3 h’ in operative duration resulted significant high rate of SP(+). For these three factors, multivariate analysis resulted that “less than 50 years old’ and ‘over 3 h in operative duration’ were significantly high.

Conclusion

This study suggests that ‘less than 50 years’ old and ‘over 3 h in operative duration’ were risk factors of postlaparoscopic SP. To protect from SP after laparoscopy, some countermeasures should be necessary especially for these patients.
Effect of short‐term vitamin D supplementation after nonsurgical periodontal treatment: A randomized, double‐masked, placebo‐controlled clinical trial
Authors: Gao Weimin , Tang Huilin , Wang Danyang , Zhou Xuan , Song Yiqing , Wang Zuomin
Published: January 2020

Objectives

This trial aimed to evaluate the efficacy and safety of vitamin D supplementation on the residual moderate and deep pockets following nonsurgical periodontal therapy.

Background

Vitamin D supplementation has potential effects on periodontitis, but current evidence remains inconclusive.

Methods

After 3 months of nonsurgical periodontal treatment, 360 patients with moderate or severe periodontitis were randomly assigned to 2000 international unit (IU)/d vitamin D3, 1000 IU/d vitamin D3, or placebo. Clinical periodontal examinations, including probing depth (PD), bleeding index (BI), plaque index (PLI), attachment loss (AL), and alveolar crest height (ACH), were performed at baseline and after 3 months of intervention.

Results

There was a slight but significant decrease in AL and PD in both vitamin D groups compared with placebo group for moderate and deep pockets. About 2000 IU/d vitamin D3 group, 1000 IU/d vitamin D3 group, and placebo group all decreased the AL for both moderate pockets (−0.4 mm vs −0.4 mm vs −0.3 mm) and deep pockets (−1.1 mm vs −1.1 mm vs −1.0 mm) (allP < .05). Similarly, PD was also decreased in these three groups for both moderate pockets and deep pockets (allP < .05). In addition, vitamin D supplementation was well tolerated, and no adverse events were reported.

Conclusions

Although statistically significant differences were observed in favor to vitamin D supplementation, the magnitude of effect size tended to be modest with limited clinical relevance and the long‐term efficacy and safety warrant further investigation.
Inflammasomes and their regulation in periodontal disease: A review
Authors: Aral Kübra , Milward Michael R. , Kapila Yvonne , Berdeli Afig , Cooper Paul R.
Published: January 2020

Interleukin‐1β (IL‐1β), which is secreted by host tissues leading to periodontal tissue inflammation, is a major pro‐inflammatory cytokine in the pathogenesis of periodontal disease. The conversion of pro‐IL‐1β into its biologically active form is controlled by multiprotein complexes named as inflammasomes, which are key regulator of host defense mechanisms and inflammasome involved diseases, including the periodontal diseases. Inflammasomes are regulated by different proteins and processes, including pyrin domain (PYD)‐only proteins (POPs), CARD‐only proteins (COPs), tripartite motif family proteins (TRIMs), autophagy, and interferons. A review of in vitro, in vivo, and clinical data from these publications revealed that several inflammasomes including (NOD)‐like receptor (NLR) pyrin domain‐containing 3 (NLRP3) and absent in melanoma 2 (AIM2) have been found to be involved in periodontal disease pathogenesis. To the best of our knowledge, the current article provides the first review of the literature focusing on studies that evaluated both inflammasomes and their regulators in periodontal disease. An upregulation for inflammasomes and a downregulation of inflammasome regulator proteins including POPs, COPs, and TRIMs have been reported in periodontal disease. Although interferons (types I and II) and autophagy have been found to be involved in periodontal disease, their possible role in inflammasome activation has not evaluated yet. Modulating the excessive inflammatory response by the use of inflammasome regulators may have potential in the management of periodontal disease.
Intuitive Interference in Geometry: An Eye‐Tracking Study
Authors: Galili Hanit , Babai Reuven , Stavy Ruth
Published: January 2020

Interference of irrelevant salient variables may cause difficulties for students. This study focused on eye tracking during the comparison of perimeters task, in which area is the interfering irrelevant salient variable. There were three trial types: congruent (larger area—larger perimeter), incongruent inverse (larger area—smaller perimeter), and incongruent equal (larger area—equal perimeter). Behavioral findings corroborated previous studies: congruent trials yielded higher accuracy and a shorter reaction time than did incongruent trials. Surprisingly, the area saliency could not be revealed in fixation location and duration measurements in incongruent inverse trials nor in the heat maps for incongruent inverse or incongruent equal trials, suggesting that such processing does not require overt attention; measures of attention shift from one geometrical shape to another were higher for incongruent equal trials, as was pupil dilation, suggesting that greater effort is associated with solving incongruent equal trials.
Independent domestication events in the blue‐cheese fungus Penicillium roqueforti
Authors: Dumas Emilie , Feurtey Alice , Rodríguez de la Vega Ricardo C. , Le Prieur Stéphanie , Snirc Alodie , Coton Monika , Thierry Anne , Coton Emmanuel , Le Piver Mélanie , Roueyre Daniel , Ropars Jeanne , Branca Antoine , Giraud Tatiana
Published: January 2020

Domestication provides an excellent framework for studying adaptive divergence. Using population genomics and phenotypic assays, we reconstructed the domestication history of the blue cheese mould Penicillium roqueforti. We showed that this fungus was domesticated twice independently. The population used in Roquefort originated from an old domestication event associated with weak bottlenecks and exhibited traits beneficial for pre‐industrial cheese production (slower growth in cheese and greater spore production on bread, the traditional multiplication medium). The other cheese population originated more recently from the selection of a single clonal lineage, was associated with all types of blue cheese worldwide except Roquefort, and displayed phenotypes more suited for industrial cheese production (high lipolytic activity, efficient cheese cavity colonization ability and salt tolerance). We detected genomic regions affected by recent positive selection and putative horizontal gene transfers. This study sheds light on the processes of rapid adaptation and raises questions about genetic resource conservation.
Gender‐specific effects of raising Year‐1 standards on medical students' academic performance and stress levels
Authors: Stegers‐Jager Karen M. , Savas Mesut , van der Waal Jeroen , van Rossum Elisabeth F. C. , Woltman Andrea M.
Published: January 2020

Context

Medical schools are challenged to create academic environments that stimulate students to improve their study progress without compromising their well‐being.

Objectives

This prospective comparative cohort study investigated the effects of raising Year‐1 standards on academic performance and on students' chronic psychological and biological stress levels.

Methods

In a Dutch medical school, students within the last Bachelor's degree cohort (n = 410) exposed to the 40/60 (67%) credit Year‐1 standard (67%‐credit cohort) were compared with students within the first cohort (n = 413) exposed to a 60/60 (100%) credit standard (100%‐credit cohort). Main outcome measures were Year‐1 pass rate (academic performance), mean score on the Perceived Stress Scale (PSS, psychological stress) and hair cortisol concentration (HCC, biological stress).

Results

Year‐1 pass rates were significantly higher in the 100%‐credit cohort (odds ratio [OR] 4.65). Interestingly, there was a significant interaction effect (OR 0.46), indicating that raising the standard was more effective for male than for female students. PSS scores (n = 234 [response rate [RR]: 57%] and n = 244 [RR: 59%] in the 67%‐ and 100%‐credit cohorts, respectively) were also significantly higher in the 100%‐credit cohort (F(1,474) = 15.08, P < .001). This applied specifically to female students in the 100%‐credit cohort. Levels of HCC (n = 181 [RR: 44%] and n = 162 [RR: 39%] respectively) did not differ between cohorts, but were significantly higher in female students (F(1,332) = 7.93, P < .01). In separate models including cohort and gender, both PSS score (OR 0.91) and HCC (OR 0.38) were significantly associated with Year‐1 performance. Only students with both high PSS scores and high HCC values were significantly at risk of lower Year‐1 pass rates (OR 0.27), particularly male students.

Conclusions

Raising the Year‐1 performance standard increased academic performance, most notably in male students. However, it also increased levels of perceived stress, especially in female students. In particular, the combination of high levels of perceived stress and biological stress, as measured by long‐term cortisol, was related to poor academic performance. The study suggests a relationship between raising performance standards and student well‐being, with differential effects in male and female students.
Synthetic biology of hypoxia
Authors: Licausi Francesco , Giuntoli Beatrice
Published: January 2020

Synthetic biology can greatly aid the investigation of fundamental regulatory mechanisms and enable their direct deployment in the host organisms of choice. In the field of plant hypoxia physiology, a synthetic biology approach has recently been exploited to infer general properties of the plant oxygen sensing mechanism, by expression of plant‐specific components in yeast. Moreover, genetic sensors have been devised to report cellular oxygen levels or physiological parameters associated with hypoxia, and orthogonal switches have been introduced in plants to trigger oxygen‐specific responses. Upcoming applications are expected, such as genetic tailoring of oxygen‐responsive traits, engineering of plant hypoxic metabolism and oxygen delivery to hypoxic tissues, and expansion of the repertoire of genetically encoded oxygen sensors.
Retracted: An Often Easily Missed Injury in the Presence of Orthopaedic Trauma: A Case Series of Derived Injury
Authors: Deng Xiang‐tian , Wang Zhong‐zheng , Zhu Jian , Tan Zhan‐chao , Wang Yu‐chuan , Zhu Yan‐bin , Chen Wei , Zhang Ying‐ze
Published: January 2020

Derived disaster is a common concept in emergencies such as earthquakes. With the progress of society, the incidence of fractures caused by high‐energy trauma has increased year by year. After the first injury, the possibility of derived injury caused by the original injury also increases rapidly. Orthopaedic surgeons, especially trauma orthopaedic surgeons, lack sufficient understanding and recognition of this kind of injury. The purpose of this article is to present a case series of an often missed injury pattern that is associated with an original injury. The diagnosis of derived injury may go unrecognized in a considerable number of cases and delayed treatment decreases the success rate of soft tissue repairing; therefore, a high index of suspicion and a proper early diagnosis is of paramount importance. We also describe the current surgical management used by the authors, and propose the concept of “derived injury”, studying its clinical significance in traumatic orthopaedics.
Cumulative incidence of Kawasaki disease with cardiac sequelae in Japan
Authors: Matsubara Yuri , Matsubara Daisuke , Ae Ryusuke , Kosami Koki , Aoyama Yasuko , Yashiro Mayumi , Makino Nobuko , Matsubara Shigeki , Nakamura Yosikazu
Published: January 2020

Background

Some patients with Kawasaki disease (KD) develop cardiac sequelae, which increase the risk of subsequent ischemic heart events. Knowing the cumulative incidence (CI) of KD with cardiac sequelae may contribute to developing health policies to prevent subsequent ischemic events in these patients.

Methods

Study participants consisted of 254 984 patients aged 0–9 years with KD who were registered in nationwide surveys in Japan from 1991–2016. We calculated the incidence probabilities by dividing the number of patients with KD aged 0–9 years by the population used in vital statistics of each calendar year. We calculated the cumulative proportion of those not affected by KD, by multiplying each probability in patients aged from age 0–9 years. The CI of KD was obtained by subtracting this value from 1. We also calculated the number of patients in each birth cohort (BC). The same was done to calculate the CI of KD‐related cardiac sequelae.

Results

The CIBC steadily increased from 0.005067 in males and 0.003668 in females in 1991 to 0.011431 in males and 0.0088253 in females in 2007. The CIBC of KD with cardiac sequelae decreased from 0.000478 in males and 0.000213 in females in 1997 to 0.000339 in males and 0.000169 in females in 2007.

Conclusion

The increasing CIBC of KD indicates an increased susceptibility to KD in accordance with birth year. The decreasing CIBC of cardiac sequelae suggests the efficacy of KD treatment.
Differences in caesarean delivery and neonatal outcomes among women of migrant origin in Finland: A population‐based study
Authors: Bastola Kalpana , Koponen Päivikki , Gissler Mika , Kinnunen Tarja I.
Published: January 2020

Background

In Finland, limited information is available on neonatal disparities among women of migrant origin.

Objective

This study investigated differences in caesarean delivery and neonatal outcomes between women of migrant origin and Finnish women in Finland.

Methods

The study was based on nationwide data from the Medical Birth Register of Finland. Our study included information on the most recent singleton birth of women delivering between January 2004 and December 2014 (N = 382 233). Women were classified into nine regional categories based on their country of origin. Generalized linear models were used to describe associations between country of origin and pregnancy outcomes adjusted for maternal age, socio‐economic status, pre‐pregnancy body mass index, parity, marital status, smoking during pregnancy, and delivery year. Finnish women were the reference group.

Results

Among the study population, almost 92% of women were of Finnish origin; the remaining 8% were of migrant origin. Among the migrant women, those of Russian/former USSR origin were the largest group (n = 11 994); the smallest group was women of Latin American/Caribbean origin (n = 739). Compared with Finnish women, women of sub‐Saharan African, South Asian, and East Asian origin were at greater risk of emergency caesarean delivery, preterm birth, low birthweight, and lower five‐minute Apgar scores for newborns. Latin American/Caribbean‐origin women were at increased risk of both elective and emergency caesarean delivery and lower five‐minute Apgar scores compared with Finnish women. Women of Russian/former USSR origin overall had a lower risk of caesarean delivery and poor neonatal outcomes compared with Finnish women.

Conclusions

We identified sub‐Saharan African, South Asian, and East Asian women as higher‐risk groups, and women from Russia/former USSR as a lower‐risk group, for emergency caesarean delivery and poor neonatal outcome compared with Finnish women. More research is needed to identify the reasons for these differences by country of origin in Finland.
Phenotyping congenital anomalies in administrative hospital records
Authors: Zylbersztejn Ania , Verfürden Maximiliane , Hardelid Pia , Gilbert Ruth , Wijlaars Linda
Published: January 2020

Background

Congenital anomalies are a major cause of co‐morbidity in children. Diagnostic code lists are increasingly used to identify congenital anomalies in administrative health records. Evidence is lacking on comparability of these code lists.

Objectives

To compare prevalence of congenital anomalies and prognostic outcomes for children with congenital anomalies identified in administrative health records using three different code lists.

Methods

We developed national cohorts of singleton livebirths in England (n = 7 354 363, 2003‐2014) and Scotland (n = 493 556, 2003‐2011). Children with congenital anomalies were identified if congenital anomaly diagnosis was recorded at birth, during subsequent hospital admission or as cause of death before 2 years old. We used three code lists: the EUROCAT list for congenital anomaly surveillance in Europe; the Hardelid list developed to identify children with chronic conditions (including congenital anomalies) admitted to hospital in England; and the Feudtner list developed to indicate children with complex chronic conditions (including congenital anomalies) admitted to hospitals in the United States. We compared prevalence, and risks of postnatal hospital readmission and death according to each code list in England and Scotland.

Results

Prevalence of congenital anomalies was highest using the EUROCAT list (4.1% of livebirths in England, 3.7% in Scotland), followed by Hardelid (3.1% and 3.0% of livebirths, respectively) and Feudtner (1.8% and 1.5% of livebirths, respectively). 67.2%‐73.3% of children with congenital anomalies in England and 65.2%‐77.0% in Scotland had at least one postnatal hospital admission across the three code lists; mortality ranged between 42.6‐75.4 and 41.5‐88.7 deaths per 1000 births in England Scotland, respectively. The risk of these adverse outcomes was highest using Feudtner and lowest using EUROCAT code lists.

Conclusions

The prevalence of congenital anomalies varied by congenital anomaly code list, over time and between countries, reflecting in part differences in hospital coding practices and admission thresholds. As a minimum, researchers using administrative health data to study congenital anomalies should report sensitivity analyses using different code lists.
Global Transmission of Live Polioviruses: Updated Dynamic Modeling of the Polio Endgame
Authors: Kalkowska Dominika A. , Pallansch Mark A. , Wassilak Steven G. F. , Cochi Stephen L. , Thompson Kimberly M.
Published: January 2020

Nearly 20 years after the year 2000 target for global wild poliovirus (WPV) eradication, live polioviruses continue to circulate with all three serotypes posing challenges for the polio endgame. We updated a global differential equation‐based poliovirus transmission and stochastic risk model to include programmatic and epidemiological experience through January 2020. We used the model to explore the likely dynamics of poliovirus transmission for 2019–2023, which coincides with a new Global Polio Eradication Initiative Strategic Plan. The model stratifies the global population into 72 blocks, each containing 10 subpopulations of approximately 10.7 million people. Exported viruses go into subpopulations within the same block and within groups of blocks that represent large preferentially mixing geographical areas (e.g., continents). We assign representative World Bank income levels to the blocks along with polio immunization and transmission assumptions, which capture some of the heterogeneity across countries while still focusing on global poliovirus transmission dynamics. We also updated estimates of reintroduction risks using available evidence. The updated model characterizes transmission dynamics and resulting polio cases consistent with the evidence through 2019. Based on recent epidemiological experience and prospective immunization assumptions for the 2019–2023 Strategic Plan, the updated model does not show successful eradication of serotype 1 WPV by 2023 or successful cessation of oral poliovirus vaccine serotype 2‐related viruses.
A Comparative Study on the Effect of Mechanical Compliance for a Safe Physical Human–Robot Interaction
Authors: She Yu , Song Siyang , Su Hai-Jun , Wang Junmin
Published: January 2020

In this paper, we study the effects of mechanical compliance on safety in physical human–robot interaction (pHRI). More specifically, we compare the effect of joint compliance and link compliance on the impact force assuming a contact occurred between a robot and a human head. We first establish pHRI system models that are composed of robot dynamics, an impact contact model, and head dynamics. These models are validated by Simscape simulation. By comparing impact results with a robotic arm made of a compliant link (CL) and compliant joint (CJ), we conclude that the CL design produces a smaller maximum impact force given the same lateral stiffness as well as other physical and geometric parameters. Furthermore, we compare the variable stiffness joint (VSJ) with the variable stiffness link (VSL) for various actuation parameters and design parameters. While decreasing stiffness of CJs cannot effectively reduce the maximum impact force, CL design is more effective in reducing impact force by varying the link stiffness. We conclude that the CL design potentially outperforms the CJ design in addressing safety in pHRI and can be used as a promising alternative solution to address the safety constraints in pHRI.
Reliability Analysis of Nonlinear Vibratory Systems Under Non-Gaussian Loads Using a Sensitivity-Based Propagation of Moments
Authors: Papadimitriou Dimitrios , Mourelatos Zissimos P. , Patil Santosh , Hu Zhen , Tsianika Vasiliki , Geroulas Vasileios
Published: January 2020

The paper proposes a new methodology for time-dependent reliability analysis of vibratory systems using a combination of a first-order, four-moment (FOFM) method and a non-Gaussian Karhunen–Loeve (NG-KL) expansion. The approach can also be used for random vibrations studies. The vibratory system is nonlinear and is excited by stationary non-Gaussian input random processes which are characterized by their first four marginal moments and autocorrelation function. The NG-KL expansion expresses each input non-Gaussian process as a linear combination of uncorrelated, non-Gaussian random variables and computes their first four moments. The FOFM method then uses the moments of the NG-KL variables to calculate the moments and autocorrelation function of the output processes based on a first-order Taylor expansion (linearization) of the system equations of motion. Using the output moments and autocorrelation function, another NG-KL expansion expresses the output processes in terms of uncorrelated non-Gaussian variables in the time domain, allowing the generation of output trajectories. The latter are used to estimate the time-dependent probability of failure using Monte Carlo simulation (MCS). The computational cost of the proposed approach is proportional to the number of NG-KL random variables and is significantly lower than that of other recently developed methodologies which are based on sampling. The accuracy and efficiency of the proposed methodology is demonstrated using a two-degree-of-freedom nonlinear vibratory system with random coefficients excited by a stationary non-Gaussian random process.
Load–Displacement Characterization in Three Degrees-of-Freedom for General Lamina Emergent Torsion Arrays
Authors: Pehrson Nathan A. , Bilancia Pietro , Magleby Spencer , Howell Larry
Published: January 2020

Lamina emergent torsion (LET) joints for use in origami-based applications enables folding of panels. Placing LET joints in series and parallel (formulating LET arrays) opens the design space to provide for tunable stiffness characteristics in other directions while maintaining the ability to fold. Analytical equations characterizing the elastic load–displacement for general serial–parallel formulations of LET arrays for three degrees-of-freedom are presented: rotation about the desired axis, in-plane rotation, and extension/compression. These equations enable the design of LET arrays for a variety of applications, including origami-based mechanisms. These general equations are verified using finite element analysis, and to show variability of the LET array design space, several verification plots over a range of parameters are provided.
A Novel Approach to Kinematic Reliability Analysis for Planar Parallel Manipulators
Authors: Zhao Qiangqiang , Guo Junkang , Zhao Dingtang , Yu Dewen , Hong Jun
Published: January 2020

Kinematic reliability is an essential index that assesses the performance of the mechanism associating with uncertainties. This study proposes a novel approach to kinematic reliability analysis for planar parallel manipulators based on error propagation on plane motion groups and clipped Gaussian in terms of joint clearance, input uncertainty, and manufacturing imperfection. First, the linear relationship between the local pose distortion coming from the passive joint and that caused by other error sources, which are all represented by the exponential coordinate, are established by means of the Baker–Campbell–Hausdorff formula. Then, the second-order nonparametric formulas of error propagation on independent and dependent plane motion groups are derived in closed form for analytically determining the mean and covariance of the pose error distribution of the end-effector. On this basis, the kinematic reliability, i.e., the probability of the pose error within the specified safe region, is evaluated by a fast algorithm. Compared to the previous methods, the proposed approach has a significantly high precision for both cases with small and large errors under small and large safe bounds, which is also very efficient. Additionally, it is available for arbitrarily distributed errors and can analyze the kinematic reliability only regarding either position or orientation as well. Finally, the effectiveness and advantages of the proposed approach are verified by comparing with the Monte Carlo simulation method.
Adaptive Wiebe Function Parameters for a Port-Fuel Injected Hydrogen-Fueled Engine
Authors: Alam Shah Saud , Depcik Christopher
Published: January 2020

Current unmanned aerial vehicle (UAV) propulsion technologies includes hydrogen fuel cells, battery systems, and internal combustion engines (ICE). However, relying on a single propulsion technology might result in a limited operational range. This can be mitigated by utilizing a hybrid configuration involving a battery pack and an ICE or a fuel cell for charging. Due to its significant weight advantage and high mass-specific energy content, hydrogen (H2) is an ideal fuel for both power plant options. However, use of H2 with an ICE requires precise operational control through combustion process simulation with the predictive approximation of the mass fraction burned profile. In this area, the relatively simple single-Wiebe function is widely deployed for a variety of different fuels, as well as combustion regimes. In general, the description of the single-Wiebe function includes the extent of complete combustion (a), magnitude of the maximum burn rate (m), and combustion duration (θd). However, the literature often provides values for these parameters without necessarily relating them to operational characteristics that can influence ICE power. As a result, it is critical to correlate the burn rate of the fuel to ICE operating parameters, such as the engine compression ratio, inlet pressure, mean piston speed, exhaust gas recirculation level, equivalence ratio, and spark timing.

Therefore, in an attempt to physically define these parameters, this effort performs a sensitivity analysis using linear regression (least squares method) to assess the impact of engine operating conditions on the Wiebe function in comparison to experimental data for port-fuel injected hydrogen ICEs. The result is a model that can estimate the values of a, m, and θd in combination with a relatively high coefficient of determination (R2) when compared to the experimental mass fraction burned profiles. Finally, others can expand this methodology to any experimental data for engine and fuel-specific Wiebe parameter determination.
Thermal Imaging Technique to Minimize the Wastage of Fruits
Authors: Gurupatham Sathish K. , Wiles Carson
Published: January 2020

This study is aimed at using non-invasive thermal imaging technique to assess fruit ripeness, including fruits which maintain skin color throughout ripening. The same sized four unripe fruits of avocado, kiwi, and peach from each variety were chosen with the same skin texture, color, and firmness in a batch for the study, for a total of four batches. Thermal images of these fruits were captured using a thermal camera for three consecutive days at a specific time under the same environmental conditions. The thermal images show that the temperature of fruits increases along with their ripeness level during ripening which happens due to the respiration of the fruits. The specific heat which is a function of temperature was calculated experimentally using a method developed by Hwang and Hayakama for five unripe and ripe fruits of each variety with the same ripeness level, skin texture, color, and firmness which confirmed this increase. This work demonstrates that thermal imaging technique is preferable and non-invasive for evaluation of the ripeness of fruits, especially which do not change their skin color during ripening such as kiwi.
Optimal Configuration Selection Through Experimental Tests on Branched Heat Exchanger With R134 Organic Fluid
Authors: Capata Roberto , Calabria Alfonso
Published: January 2020

The aim of this work the analysis of compact branched heat exchangers, by measuring thermal efficiency and the pressure drop in several experimental tests. Three different heat exchanger configuration have been considered. In the first device, the constant efflux velocity, in the internal channels, was imposed. The second exchanger was realized by imposing constant the value of the Reynolds number. The last device was created according to the instructions of the constructal theory. All three exchangers are aluminum made. In addition, in order to have a more detailed knowledge of the phenomenon and to identify what are the parameters that govern heat transfer, an organic fluid has been used and tested. In our case R1234 organic fluid. It was therefore necessary to realize an appropriate test bench for the use of the organic fluid. Once realized, several tests were conducted. Finally in order to be able to indicate which configuration results the optimal one, the Prandtl and Nusselt numbers were obtained and compared.
Preformed Particle Gels (PPGs) Compressibility Measurements in the Reservoirs Channels
Authors: Elsharafi Mahmoud O.
Published: January 2020

Excess water production has become a significant problem to the oil-field operations as reservoirs mature. Preformed particle gels (PPGs) has been used widely to reduce the permeability of the formation channels. Therefore, water production decreases and sweeps efficiency increases in mature oil-fields. The work on this research will help out and determine what factors affect the PPG pack compressibility. It will determine the compressibility of swollen PPGs which could affect the selection and the design of the best PPG treatments in mature reservoirs. A transparent model was designed to observe the compression of gel particles in fluid channels at different injection pressures, and thus to study the effect of different parameters on PPG blocking efficiency. After each injection pressure, PPG compressibility was calculated to study the effect of various particle sizes, gel types, and brine concentrations on the PPG compressibility. Permeable gel packs were formed in fluid channels by gel particles and its compressibility depends on PPG particle size, gel strength, types, brine concentration, and load pressure. Gel pack is compressed and its compressibility is increased as injection pressure increases. A weak PPG with large particle size, low brine concentration, and low gel strength compressed more than a strong PPG with small particle size, high brine concentration, and high gel strength. The increase of the gel compressibility cause more reduction on the gel permeability on the fluid channels. A gel pack which has a desired compressibility can be designed by selecting proper gel strength and particle sizes at reservoir pressures.
First-Principle Calculations of the Binding Energy of the Coating Components of New Generation Dental Implants
Authors: Balueva Alla V. , Dashevskiy Ilia N. , Todebush Patricia , Campbell Chasen , Valdez Eduardo
Published: January 2020

We propose a new method of calculating adhesive strength of a novel bioactive nano-crystralline hydroxyapatite (HAp) coating of a dental implant by methods of Density Functional Theory (DFT) and Molecular Dynamics (MD) simulation. Hydroxyapatite is the material similar to the bone — that is why it is used in odontology to cover the implant to improve the process of osseointegration of the implant with the bone. It is also important to have a strong adhesive bond between the coating and the implant to avoid unpleasant situations dealing with the peeling of the coating.

Our research focuses on understanding the strength of the bonds of interactions occurring during the process of spraying the dental implants, proposing factors that affect that strength, and ultimately looking at ways to improve the coating process. The goal of this work is to determine the strength of the interactions of the bio-nanocoating, hydroxyapatite, with titanium, which is the common material for the implant. Specifically the binding energy of different combinations of the constituents of the hydroxyapatite coating with titanium are calculated and ranked in order of intermolecular interactions. In the future, these components will be used to calculate the total binding energy of the HAp unit cell and the Ti (II) cation.
Design and Analysis of a Monolithic Compliant Dwell Mechanism
Authors: Lin Hongkuan , Tekes Ayse
Published: January 2020

A novel, monolithic flexible translational dwell mechanism that is driven by a DC motor is designed in this study. Mechanism consists of an initially straight, large deflecting pinned-pinned buckling beam as a coupler, semi-circular compliant arc as a follower, rigid crank and a slider. An approximate dwell motion is created since the slider doesn’t move until the critical buckling load of the flexible coupler is achieved and then snaps to its maximum displacement by pushing the follower arc beam. As the maximum bending on the arc is reached, slider moves back to its initial as the crank follows a full rotation. Dynamical lumped model of the mechanism is obtained by integrating first and second kind of elliptic integral solution of pinned-pinned beam with polynomial formulation method. Optimal dimensions and geometric positions are explored using commercially available FEA program (ADAMs). Mechanism is built by 3D printing the entire mechanism as a single piece using polyethylene terephthalate glycol (PETG). Mathematical model of the mechanism is validated through experimental setup and ADAMs simulations.
Numerical CFD / FSI Study of Teflon and Dacron for Use in the Femoral Artery Graft Procedure
Authors: Sandhu Sukwinder , Anderson Kevin R.
Published: January 2020

This paper presents Fluid Structure Interaction modeling of candidate implant materials used in the femoral artery graft medical procedure. Two candidate implant materials, namely Teflon and Dacron are considered and modeled using Computational Fluid Dynamics (CFD) and structural Finite Element Analysis (FEA) to obtain Fluid Structure Interaction (FSI) developed stresses within the candidate materials as a result of non-Newtonian blood flowing in a pulsatile unsteady fashion into the femoral artery implant tube. The pertinent findings for a pulsatile velocity maximum magnitude of 0.3 m/s and period of oscillation of 2.75 sec are as follows. For the biological tissue the wall shear stress is found to be 2.15 × 104 Pa, the hoop stress is found to be 1.6 × 104 Pa. For the Teflon implant material, the wall shear stress is found to be 1.177 × 104 Pa, the hoop stress is found to be 2.2 × 104 Pa. For the Dacron implant material the wall shear stress is found to by 3.9 × 104 Pa, the hoop stress is found to be 2.17 × 104 Pa. Based upon the analysis herein the PTFE material would be recommended.
CFD Study of Particle and Compressible Flow Interaction for a Twin Wire Arc Spraying System
Authors: Faull Raymond , Wagner Nicole , Anderson Kevin
Published: January 2020

Plasma spraying is used in various industries for additive manufacturing applications to apply materials onto a workpiece. Such applications could be for the purpose of repair, protection against corrosion, wear-resistance, or enhancing surface properties. One plasma spraying method is the twin wire arc spraying (TWAS) process that utilizes two electrically conductive wires, across which an electric arc is generated at their meeting point. The molten droplets that are created are propelled by an atomizing gas towards a substrate on which the coating is deposited. The TWAS process offers low workpiece heating and high deposition rates at a lower cost compared to other plasma spraying techniques. As the spray angle for this technique is relatively large (15 degree half angle), particles are lost in the process, lowering the yield of deposited material. The motivation of this project was to constrict the particle flow and reduce the loss of particles that are ejected by the spraying torch. Torch nozzles were designed to help the particle trajectory match the axial flow direction of the atomizing gas flow. Simulations using ANSYS FLUENT Computational Fluid Dynamics (CFD) software was utilized to model both the atomizing gas flow and particle flow for a TWAS system. Various nozzle configurations with arc jet angles between 30–75 degrees showed only small effects on gas flow velocity and shape, with no significant variations in particle flow. These results indicate that nozzle configurations are only one factor in determining particle trajectory, and that phase changes and heat transfer need to be considered as well.
Identification and Analysis of the Biomechanical Parameters Used for the Assessment of Normal and Pathological Gait: A Literature Review
Authors: Arellano-González Juan C. , Medellín-Castillo Hugo I. , Cervantes-Sánchez J. Jesús
Published: January 2020

The analysis of human gait represents a valuable tool for an early and timely identification of diseases and pathologies, as well as to follow up treatments and rehabilitation programs. However, although several research works in the literature have addressed the assessment of human gait as a diagnostic tool, few works have focused on the biomechanical parameters and metrics needed for such practice. This work presents the results of an investigation carried out to identify and analyze the biomechanical parameters used in the literature to assess the human walking, both pathological and normal. For this purpose, a literature review was conducted to detect and analyze the biomechanical parameters. A classification of these parameters based on the application area is proposed and comprises clinical, sport and exploration. These parameters are also classified according to the origin of the problem into musculoskeletal, neurological and circulatory. The biomechanical parameters identified are analyzed and discussed using set theory. The results indicate that the analysis of the spatiotemporal parameters of the gait allows a detailed and economic study of this mode of locomotion. The most used gait parameters are: step length, stride length, step width, gait speed, gait phases, cadence, swing time and stance time. On the other hand, the study of gait in the clinical area makes use of nearly all the gait parameters reported in the literature, i.e. spatial, temporal, angular, force and other specific parameters according to the type of pathology being analyzed.
An Air Suspension System With Adjustable Height, Damping and Stiffness Using No Viscous Dampers
Authors: Kashani Reza
Published: January 2020

Air suspension is gaining more and more popularity with both the auto industry and drivers. Traditionally the height adjustability aspect of air suspension systems has been their main attracting attribute. More recently, resolving the classic conflict of combining comfortable ride with sport handling in a single suspension setup has become the main attraction of air suspension.

An air suspension system has been developed which in addition to height adjustment, can adjust its damping and stiffness in real time with using neither viscous dampers nor any additional actuators. This is done by real-time adjustment air flow to and from the air springs using proportional valves. Measured relative displacement and acceleration as well as estimated velocity of the sprung mass with respect to unspring mass at each corner are fedback, thru their corresponding gains, to create the control signal that adjusts the proportional valve with the goal of controlling the height, stiffness, and damping at that corner.

In a numerical study followed by laboratory testing, the effectiveness of the proposed air suspension system in terms of its ability to vary the damping and stiffness as well as the height of the suspension system is demonstrated.
Performance Analysis and Parametric Studies of Nose Landing Gear Shimmy Dampers
Authors: Rahmani Mohsen , Behdinan Kamran
Published: January 2020

Self-induced mechanical oscillation of nose landing gears designated as shimmy is a major safety challenge for aircrafts. The rotational-lateral shimmy vibrations can occur during takeoff, taxiing, and landing and needs to be sufficiently controlled to avoid escalation and catastrophic failure of the landing gear system. Existing solutions for shimmy problem are largely passive control strategies known as shimmy dampers. Despite numerous studies on the source of shimmy and its trends, investigations on the design and performance analysis of shimmy dampers are scarce. From a design perspective, it is crucial to quantify the effective stiffness and damping supplied by the shimmy damper to the system in different operation states. Furthermore, the sensitivity of the damper performance to its design parameters needs to be thoroughly investigated in order to optimize the design for a particular aircraft. In this study, core relationships for three shimmy dampers are presented and used to perform sensitivity studies. These dampers are concepts by Boeing, Collins Aerospace (formerly UTAS), and a new one designated as the Symmetric Torque Link Damper (STLD). The influence of design parameters on the dampers’ performance is studied and observed trends are discussed in the light of inherent trade-offs. Subsequently, a nonlinear Multibody Dynamic model of the landing gear is utilized to obtain sample time histories of oscillations for each shimmy damper in order to highlight the performance differences and to demonstrate the influence of design parameters. Directions for designing future shimmy dampers and recommendations for optimizing them are offered.