bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic trajectories of volatile and non‐volatile specialised metabolites in ‘overnight’ fragrant flowers of Murraya paniculata
Authors: Paul I. , Chatterjee A. , Maiti S. , Bhadoria P.B.S. , Mitra A.
Published: March 2019

Ephemeral flowers, especially nocturnal ones, usually emit characteristic scent profiles within their post‐anthesis lifespans of a few hours. Whether these flowers exhibit temporal variability in the composition and profile of volatile and non‐volatile specialised metabolites has received little attention.

Flowers of Murraya paniculata bloom in the evenings during the summer and monsoon, and their sweet, intense fragrance enhances the plant's value as an ornamental. We aimed to investigate profiles of both volatile and non‐volatile endogenous specialised metabolites (ESM) in nocturnal ephemeral flowers of M. paniculata to examine whether any biochemically diverse groups of ESM follow distinct patterns of accumulation while maintaining synchrony with defensive physiological functions.

Targeted ESM contents of M. paniculata flowers were profiled at ten time points at 2‐h intervals, starting from late bud stage (afternoon) up to the start of petal senescence (mid‐morning). Emitted volatiles were monitored continuously within the whole 20‐h period using headspace sampling. The ESM contents were mapped by time point to obtain a highly dynamic and biochemically diverse profile. Relative temporal patterns of ESM accumulation indicated that the active fragrance‐emitting period might be divided into ‘early bloom’, ‘mid‐bloom’ and ‘late bloom’ phases. Early and late bloom phases were characterised by high free radical generation, with immediate enhancement of antioxidant enzymes and phenolic compounds. The mid‐bloom phase was relatively stable and dedicated to maximum fragrance emission, with provision for strong terpenoid‐mediated defence against herbivores. The late bloom phase merged into senescence with the start of daylight; however, even the senescent petals continued to emit fragrance to attract diurnal pollinators.

Our study suggests that dynamic relations between the different ESM groups regulate the short‐term requirements of floral advertisement and phytochemical defence in this ephemeral flower. This study also provided fundamental information on the temporal occurrence of emitted volatiles and internal pools of specialised metabolites in M. paniculata flowers, which could serve as an important model for pollination biology of Rutaceae, which includes many important fruit crops.
Pulmonary artery enlargement predicts poor outcome during acute exacerbations of fibrotic interstitial lung disease
Authors: Kogo Mariko , Otsuka Kojiro , Morimoto Takeshi , Nagata Kazuma , Nakagawa Atsushi , Tomii Keisuke
Published: March 2019

Background and objective

In fibrotic interstitial lung disease (f‐ILD), pulmonary artery diameter to ascending aorta diameter ratio (PA/A) ≥ 1 during the stable stage is associated with worse outcomes; however, the effect of acute exacerbation (AE) on the PA/A is unknown.

Methods

Patients with a diagnosis of AE of f‐ILD and with a computed tomography (CT) scan performed during stable period to confirm background fibrosis, as well as a CT scan at admission, were included. The pulmonary arterial diameter, ascending aortic diameter and PA/A were measured using CT during AE and CT prior to AE, when available, to evaluate the changes. Demographic data, co‐morbidities and clinical outcome (90‐day mortality) were analysed.

Results

Of the 123 patients included, 45 had a PA/A ≥ 1 during AE and compared to the PA/A < 1 group, they were younger, had lower % vital capacity (VC) and % forced vital capacity (FVC), required more long‐term oxygen therapy and other treatments, and had lower PaO2/FiO2 (P/F) ratios. During AE, the PA/A increased from that during stable periods (P < 0.001), and a PA/A ≥ 1 was significantly associated with 90‐day mortality both before and after adjustment for age, the P/F ratio at admission, long‐term oxygen therapy usage and the type of background f‐ILD (P = 0.018 and 0.025).

Conclusion

To the best of our knowledge, this is the first longitudinal examination of the PA/A ratio and evaluation during AE of f‐ILD. Our data show that a PA/A ≥ 1 during AE predicted poor survival outcome in f‐ILD.
Family members’ experiences of waiting in intensive care: a concept analysis
Authors: Björk Kristofer , Lindahl Berit , Fridh Isabell
Published: March 2019

Aim

The aim of this study was to explore the meaning of family members’ experience of waiting in an intensive care context using Rodgers’ evolutionary method of concept analysis.

Method

Systematic searches in CINAHL and PubMed retrieved 38 articles which illustrated the waiting experienced by family members in an intensive care context. Rodgers’ evolutionary method of concept analysis was applied to the data.

Findings

In total, five elements of the concept were identified in the analysis. These were as follows: living in limbo; feeling helpless and powerless; hoping; enduring; and fearing the worst. Family members’ vigilance regarding their relative proved to be a related concept, but vigilance does not share the same set of attributes. The consequences of waiting were often negative for the relatives and caused them suffering. The references show that the concept was manifested in different situations and in intensive care units (ICUs) with various types of specialties.

Conclusions

The application of concept analysis has brought a deeper understanding and meaning to the experience of waiting among family members in an intensive care context. This may provide professionals with an awareness of how to take care of family members in this situation. The waiting is inevitable, but improved communication between the ICU staff and family members is necessary to reduce stress and alleviate the suffering of family members. It is important to acknowledge that waiting cannot be eliminated but family‐centred care, including a friendly and welcoming hospital environment, can ease the burden of family members with a loved one in an ICU.
Factors related to self‐rated health and life satisfaction one year after radical prostatectomy for localised prostate cancer: a cross‐sectional survey
Authors: Talvitie Anna‐Maija , Ojala Hanna , Tammela Teuvo , Koivisto Anna‐Maija , Pietilä Ilkka
Published: March 2019

Background

Localised prostate cancer affects patient's quality of life in many ways. The aim of this study was to explore factors related to self‐rated health and life satisfaction for patients treated for prostate cancer, and to compare the results of these generic quality‐of‐life measures to the prostate cancer‐specific quality‐of‐life measure (UCLA Prostate Cancer Index), which focuses on physical functioning.

Material and methods

This cross‐sectional survey was carried out among 183 men who underwent radical prostatectomy in 2012–2015 at a university hospital in Finland and were seen 1 year postsurgery. Approval from an ethics committee and written consents from participants were received. A questionnaire was used to evaluate patients’ perceived quality of life. Logistic regression model, Spearman's correlation, Kruskal–Wallis test and Mann–Whitney U‐test were used to analyse factors related to quality of life.

Results

Of the 183 men in the study, 63% rated their health status as good, and 70% were satisfied with their lives after prostatectomy. Older age and better urinary function were the only factors that explained both better self‐rated health and better satisfaction with life. The patients seemed not to interpret problems with sexual function as health‐related problems. In our sample, sexual dysfunction was relatively severe, but patients considered them to be less harmful than urinary or bowel symptoms. Interestingly, 24% of the men with low sexual function did not find that dysfunction bothersome.

Conclusions

Objectively measured physical functioning is not necessarily in line with patients’ experienced satisfaction with life and their self‐ratings of health. More longitudinal and qualitative research is needed about the meanings that patients attach to physical treatment side effects and the extent to which they can adapt to them over time. With a bigger sample and longer follow‐up time, it would be possible to identify men who particularly benefited from pretreatment counselling.
Perceptions on nurse–nurse collaboration among registered nurses in Finland and Norway
Authors: Ylitörmänen Tuija , Kvist Tarja , Turunen Hannele
Published: March 2019

Background

Intraprofessional collaboration necessitates understanding and knowledge on how nurses perceive each other and what factors promote good collaboration. The relationship between nurse–nurse collaboration has been explored relatively little, though intraprofessional collaboration is an essential factor for a healthy work environment.

Aim

This study explores the Finnish and the Norwegian nurses’ perceptions of nurse–nurse collaboration in nursing care and factors associated with those perceptions.

Design

A cross‐sectional quantitative study design.

Methods

In 2015, data were collected from 406 Finnish and Norwegian RNs in two acute‐care hospitals, by employing the Dougherty and Larson's Nurse‐Nurse Collaboration Scale (NNCS). Descriptive statistics, cross‐tabulations, Pearson's chi‐Square tests and multivariate anova were used for analysis. Ethical approval for this study was obtained from ethics committees in both countries.

Results

Findings indicated that the perception of nurse–nurse collaboration was good in both countries. However, significant inter‐country differences were found in the collaboration subscales. Compared with their Finnish counterparts, Norwegian nurses awarded higher scores to conflict management, communication, shared process, coordination and professionalism. The results suggest that nurse characteristics, such as main working time and total work experience, were related to the perception of collaboration.

Conclusion

The subscales with the highest scores in both countries were professionalism, shared process and communication. Factors such as conflict management and coordination are areas which should be emphasised to achieve good collaboration between nurses. Here, nurse leaders play an important part in assessing and improving RN‐RN collaboration.
Usefulness of nursing theory‐guided practice: an integrative review
Authors: Younas Ahtisham , Quennell Shannon
Published: March 2019

Background

Nursing theory‐guided practice helps improve the quality of nursing care because it allows nurses to articulate what they do for patients and why they do it. However, the usefulness of nursing theory‐guided practice has been questioned and more emphasis has been placed on evidence‐based nursing and traditional practice. Therefore, an examination of experimental studies was undertaken to analyse the extent of use and usefulness of nursing theories in guiding practice. We reviewed experimental studies because in this era of evidence‐based practice, these designs are given more weightage over other research designs. This examination would corroborate the usefulness of nursing theory‐guided practice compared to traditional practice.

Methods

An integrative review was conducted. Literature search was performed within multiple databases, and 35 studies were reviewed and appraised.

Results

Majority of the studies were from Iran, the United States and Turkey and used Orem's self‐care model, Roy's adaptation model and Peplau's theory of interpersonal relations. The effect of theory‐guided interventions was evaluated in improving quality of life, self‐efficacy, self‐care and stress of patients with chronic, acute, cardiac and psychological illnesses. The quality rating was judged to be strong for three studies, moderate for 25 studies and weak for seven studies. All of the strongly rated studies found nursing theory‐guided interventions useful. Overall, nursing theory‐guided interventions improved all of studied outcomes in 26 studies and at least one outcome in nine studies. None of the studies reported that nursing theory‐guided interventions as not useful.

Conclusion

Nursing theories have guided practice in both eastern and Western countries, and theory‐guided practice has been found useful compared to traditional nursing practice. Therefore, nurses should continue to guide their nursing practice through the lens of nursing theories and should continue to evaluate the effectiveness of nursing theory‐guided practice.
Sleepless nights and sleepy days: a qualitative study exploring the experiences of patients with chronic heart failure and newly verified sleep‐disordered breathing
Authors: Gullvåg Marianne , Gjeilo Kari Hanne , Fålun Nina , Norekvål Tone M. , Mo Rune , Broström Anders
Published: March 2019

Background

Sleep‐disordered breathing, including obstructive sleep apnoea and central sleep apnoea, is a common disorder among patients with chronic heart failure. Obstructive sleep apnoea is often treated with continuous positive airway pressure, but central sleep apnoea lacks a clear treatment option. Knowledge of how sleep‐disordered breathing is experienced (e.g. difficulties and care needs) and handled (e.g. self‐care actions) by the patients is limited, but needed, to provide patient‐centred care.

Aim

To explore how newly verified sleep‐disordered breathing is experienced by patients with chronic heart failure.

Methods

Data were collected through semi‐structured interviews and analysed with qualitative content analysis. Seventeen participants (14 men, three women), mean age 60 years (range 41–80) diagnosed with chronic heart failure and objectively verified sleep‐disordered breathing (nine obstructive, seven central and one mixed) were strategically selected from heart failure outpatient clinics at two Norwegian university hospitals.

Results

Patients with chronic heart failure and newly verified sleep‐disordered breathing (SDB) described experiences of poor sleep that had consequences for their daily life and their partners. Different self‐care strategies were revealed, but they were based on ‘common sense’ and were not evidence‐based. The awareness of having SDB was varied; for some, it gave an explanation to their trouble while others were surprised by the finding.

Conclusion

Patients with chronic heart failure and sleep‐disordered breathing experienced reduced sleep quality, influencing their daily life. Possible underlying causes of disrupted sleep, such as sleep‐disordered breathing, should be identified to establish proper patient‐centred treatment strategies. There is a need for new strategies to approach patients with chronic heart failure (i.e. those with central sleep apnoea) who are not subject to continuous positive airway pressure treatment for their sleep‐disordered breathing.
Family members’ experiences in adult intensive care units: a systematic review
Authors: Imanipour Masoomeh , Kiwanuka Frank , Akhavan Rad Sanaz , Masaba Ronald , Alemayehu Yisak Hagos
Published: March 2019

Background

Admission to Intensive Care Units (ICU) exposures family members to a new environment, advanced monitoring systems and aggressive treatments. This is coupled with the critical condition of the patient being admitted in ICU. In such times of stress and crisis, families have varying experiences as they navigate the ICU journey. These happen more or less in chronological phases.

Aim

This review sought to describe the experiences of family members of patients admitted in adult ICUs.

Data sources

Four electronic databases (PubMed, Embase, Scopus and Web of Science) were searched, using keywords and free‐text words.

Methods

Curation of the review question involved problem identification, a scoping search, developing a search strategy, evaluation, data analysis, and reporting. Freehand search in reference lists of eligible articles was also done to obtain potentially eligible articles published in English language between 2007 and 2018. Studies were included if they reported on family members’ experiences in adult ICUs. This review conforms to the Preferred Reporting Items for Systematic review and Meta‐Analysis (PRISMA).

Results

Upon completion of the screening process, 28 studies were included. Most studies were conducted in the United States while no study was identified from Africa. We report on 717 family members. Family members’ experience of the ICU journey falls into three main themes: (i) Floating, (ii) Probing and (iii) Continuity or Closure.

Conclusion

As healthcare technology advances, the ICU environment consequently needs to evolve. As such, healthcare providers will need to adjust their practice, support and consider the patients’ family as the other part of the patient and members of the care team in order to meet their expectations. Further research highlighting family members’ experience of the ICU journey in Africa is needed.
Accessibility, utilisation and acceptability of a county‐based home care service for sick children in Sweden
Authors: Castor Charlotte , Hallström Inger Kristensson , Landgren Kajsa , Hansson Helena
Published: March 2019

Background

Home care service (HCS) for sick children is a complex healthcare service, which can be organised in various models. Despite the possibility to support family everyday life, the accessibility and utilisation may still be limited. The aim of this study was to (i) determine characteristics in referrals to county‐based HCS, (ii) determine characteristics of referred children and (iii) assess acceptability of parents and children in county‐based HCS.

Methods

Data on characteristics of referrals and referred children were collected from medical records of children 0–17 years of age, referred to eight HCS units during 2015–2018. Data on parental and child overall experience, satisfaction of, safety with, and preference for care, were collected from parents by a questionnaire. Descriptive and comparative statistics were used to analyse the data.

Results

Three hundred and fifty‐five referrals led to one or more periods of HCS for 171 children in various ages with a wide range of illnesses. Children with cancer (30%) composed the largest group and administration of intravenous antibiotics accounted for 56% of the care tasks. Seven per cent of the referrals were to palliative home care. Thirty‐eight referrals of 34 children were refused. There was an uneven distribution of the indication for referral, acceptance rate and diagnoses of children among HCS units. Parents reported their and their child's experience with the HCS visit as highly positive and preferred home care to hospital care in over 96% of the HCS in 212 visits.

Conclusion

County‐based HCS constitutes a supplement to hospital care for sick children with various illnesses through different stages of acute and long‐term illness and at end of life, with high levels of acceptability. Few referrals and variation in referral characteristics and acceptance rate of referrals between HCS units led to unequal and inequitable accessibility and utilisation of HCS.
Left atrial volume in elite athletes: A meta‐analysis of echocardiographic studies
Authors: Cuspidi Cesare , Sala Carla , Tadic Marijana , Baccanelli Giovanni , Gherbesi Elisa , Grassi Guido , Mancia Giuseppe
Published: March 2019

Aim

Information on left atrium (LA) enlargement, as assessed by LA volume (LAV) instead of LA diameter, in the athletic population is scanty. To expand current knowledge on this issue, we performed an updated meta‐analysis of echocardiographic studies.

Design

The Ovid MEDLINE, PubMed, and Cochrane CENTRAL databases were searched for English language articles without time restriction up to February 2018 through focused, high sensitive search strategies. Studies were identified by crossing the following search terms: “athletes,” “physical training,” “left atrial size,” “left atrial volume,” “atrial function,” and “echocardiography.”.

Results

Overall, 3145 subjects (2425 elite athletes and 720 active but not trained healthy controls) were included in 16 studies. Average LAV indexed to BSA (LAVI) was 37% higher in athletes as compared to nonathletic controls (31.0 ± 1.4 mL/m2 vs 22.2 ± 0.9 mL/m2), the standard means difference (SMD) being 1.12 ± 0.13 (CI: 0.86‐1.89, P < 0.0001). SMD was higher in high‐dynamic/high‐static trained athletes (1.78 ± 0.24, CI: 1.30‐2.20, P < 0.001) than in high‐dynamic/low‐static trained athletes 1.00 ± 0.16, CI: 0.70‐1.30, P < 0.001). The statistical difference did not change after correction for publication bias and was not affected by a single study effect.

Conclusions

Our meta‐analysis suggests that the adaptation of LA to intensive physical training in elite athletes is characterized by a marked increase in LAVI; LA dilation is more pronounced in the subgroup of high‐dynamic/high‐static trained athletes. The functional and clinical implications related to advanced LA dilation in athletes and particularly in those engaged in high‐dynamic/high‐static disciplines deserve further investigations.
New image analysis tool for facial pore characterization and assessment
Authors: Dissanayake Bandara , Miyamoto Kukizo , Purwar Ankur , Chye Rose , Matsubara Akira
Published: March 2019

Background

Visible facial pores are an important cosmetic concern especially among young females. Number of different methodologies is used today to assess facial pores and efficacy of technologies. Main limitations of these methods are, however, (a) moderate correlation with visual perception, (b) characterization is mostly limited to size or number of pores, (c) measurement is limited to a smaller area of face, and (d) operational difficulties. In order to address these limitations, we developed a 2D image analysis tool to assess and characterize visible facial pores.

Materials and Methods

Two clinical studies were conducted with northeast Asian skin type females. In the first study, 40 subjects age between 20 and 40 with different degree of pore severity were recruited. In the second study, 15 subjects age between 20 and 40 with enlarged pores were recruited to evaluate pore product efficacy. In both studies, full face images were taken using Visia‐CR and assessed by means of the newly developed tool and visual grading.

Results

A high correlation between visual grading and pore size was obtained (r = 0.86). New methodology was able to differentiate products similar to visual grading.

Conclusion

Novel pore image analysis method using 2D skin surface imaging with standard photography has been developed and validated. In addition to pore size measurements, we propose this method to be used to measure pore shape, color, and orientation for a comprehensive characterization of facial pores.
Epstein‐Barr virus‐associated smooth muscle tumors after lung transplantation
Authors: Hirama Takashi , Tikkanen Jussi , Pal Prodipto , Cleary Sean , Binnie Matthew
Published: March 2019

Background

Recipients of solid organ transplants are prone to various complications that are seldom encountered in immunocompetent individuals. Post‐transplant lymphoproliferative disorder (PTLD) is the best known and commonest Epstein‐Barr Virus (EBV)‐associated malignancy post solid organ transplant. EBV‐associated smooth muscle tumors (EBV‐SMT) including leiomyomas and leiomyosarcomas are rare and much less studied than PTLD. We recently encountered two cases of EBV‐SMT post lung transplantation and here we summarize their clinical features and course together with a literature review.

Method

Clinical data and treatment details of two patients who developed EBV‐SMT were reviewed and retrieved up to December 31, 2017. English literature was searched through the PubMed database from 1965 to 2017 for studies of the association between lung transplant and EBV‐SMT.

Results

The incidence of PTLD is higher among lung transplant recipients compared to kidney transplant recipients, an observation that has been attributed to stronger immune suppression in the lung patients. EBV‐SMT showed a higher incidence among kidney recipients than among lung recipients, suggesting that the degree of immunosuppression may be a less important factor in the development of EBV‐SMT. EBV‐SMT has most often been seen among lung transplant recipients with EBV mismatch.

Conclusions

Because EBV‐SMT is a rare tumor, its incidence, risk factors, and optimal management have not been well‐defined and further study is needed.
Phaeohyphomycosis caused by Medicopsis romeroi in solid organ transplant recipients: Report of two cases and comprehensive review of the literature
Authors: Los‐Arcos Ibai , Royuela Meritxell , Martín‐Gómez M. Teresa , Alastruey‐Izquierdo Ana , Sellarès Joana , Perelló Manel , Castells Lluís , Dopazo Cristina , Gavaldà Joan , Len Oscar
Published: March 2019

Medicopsis romeroi is a melanized coelomycetous fungus, mainly found in tropical and subtropical regions and an uncommon cause of infection in solid organ transplant (SOT) recipients. We describe two cases of SOT recipients diagnosed with phaeohyphomycosis due to M romeroi and provide a comprehensive literature review. These infections should be considered in patients native to tropical countries with a localized skin and soft tissue infection. Sequencing is needed for accurate identification of uncommon melanized fungi. Surgical treatment is recommended to cure the infection and co‐adjunctive oral antifungals should be considered.
Science Teacher Preparation: Themes of Exemplary STEM Inquiry Instruction
Authors: Wei Liping , LeSage-Clements Teresa
Published: March 2019

In response to increased attention to STEM teacher preparation, this paper intends to investigate the inquiry methods for improving STEM teaching and learning through unpacking the instructional implementation of a “Science as Inquiry” course in the teacher education program of a public university in a Southwestern state of the U.S. The purpose is examining the features underlying inquiry approach to science instruction, and therefore facilitating the dissemination and adoption of effective STEM instructional practices. Five themes are illuminated, presenting an exemplar of inquiry-based science instruction: a) nourishing an inquiring mind; (b) seeking the depth of understanding; (c) enacting guided inquiry; (d) cultivating cooperative learning; and (e) emphasizing experience-based learning. It is hopeful that this study can highlight the continued need for innovations in STEM teaching pedagogies and contribute to nation’s commitment to supporting and improving STEM education.
Model Predictive Control-Based Path-Following for Tail-Actuated Robotic Fish
Authors: Castaño Maria L. , Tan Xiaobo
Published: March 2019

There has been an increasing interest in the use of autonomous underwater robots to monitor freshwater and marine environments. In particular, robots that propel and maneuver themselves like fish, often known as robotic fish, have emerged as mobile sensing platforms for aquatic environments. Highly nonlinear and often under-actuated dynamics of robotic fish present significant challenges in control of these robots. In this work, we propose a nonlinear model predictive control (NMPC) approach to path-following of a tail-actuated robotic fish that accommodates the nonlinear dynamics and actuation constraints while minimizing the control effort. Considering the cyclic nature of tail actuation, the control design is based on an averaged dynamic model, where the hydrodynamic force generated by tail beating is captured using Lighthill's large-amplitude elongated-body theory. A computationally efficient approach is developed to identify the model parameters based on the measured swimming and turning data for the robot. With the tail beat frequency fixed, the bias and amplitude of the tail oscillation are treated as physical variables to be manipulated, which are related to the control inputs via a nonlinear map. A control projection method is introduced to accommodate the sector-shaped constraints of the control inputs while minimizing the optimization complexity in solving the NMPC problem. Both simulation and experimental results support the efficacy of the proposed approach. In particular, the advantages of the control projection method are shown via comparison with alternative approaches.
Tracking of Periodic Trajectories for Switched Systems Under Time-Varying Asynchronous Switching
Authors: Ma Guoqi , Liu Xinghua , Pagilla Prabhakar R. , Ge Shuzhi Sam
Published: March 2019

In this technical brief, we provide an asynchronous modified repetitive controller design to address the periodic trajectory tracking problem for switched systems with time-varying switching delays between plant modes and controllers. In the feedback channel, a dynamic output feedback mechanism is adopted. By utilizing the lifting technique, the dynamic output feedback-based switched repetitive control system is transformed into a continuous-discrete two-dimensional (2D) model to differentiate the control and learning actions involved in the repetitive controller. For the transformed 2D model, by constructing a piecewise Lyapunov functional and utilizing a matrix decomposition approach, sufficient conditions in terms of linear matrix inequalities (LMIs) and the average dwell time are developed to guarantee closed-loop exponential stability. The performance of the proposed approach is illustrated via a switched RLC series circuit example and numerical simulations are provided.
Data-Driven Backstepping Control of Underactuated Mechanical Systems
Authors: Huang Jingwen , Zhang Tingting , Sun Jian-Qiao
Published: March 2019

This paper studies control problems of underactuated mechanical systems with model uncertainties. The control is designed with the method of backstepping. The first-order low-pass filters are used to estimate the unknown quantities and to avoid the “explosion of terms.” A novel method is also proposed to implement the control without the knowledge of the control coefficient, which makes the whole process of backstepping control data-driven. The stability of the proposed control in the Lyapunov sense is studied. It is numerically and experimentally validated, and compared with the well-known model-based linear quadratic regulator (LQR) control. The data-driven backstepping control is found to provide comparable performances to that of the LQR control with the advantage of being model-free and robust.
Numerical Study on Mitigation of Flow Maldistribution in Parallel Microchannel Heat Sink: Channels Variable Width Versus Variable Height Approach
Authors: Kumar Ritunesh , Singh Gurjeet , Mikielewicz Dariusz
Published: March 2019

Microchannel heat sink on one hand enjoys benefits of intensified several folds heat transfer performance but on the other hand has to suffer aggravated form of trifling limitations associated with imperfect hydrodynamics and heat transfer behavior. Flow maldistribution is one of such limitation that exaggerates temperature nonuniformity across parallel microchannels leading to increase in maximum base temperature. Recently, variable width channels approach had been proposed by the current authors to mitigate the flow maldistribution in parallel microchannels heat sinks (MCHS), and in the current numerical study, variable height approach is opted for flow maldistribution mitigation. It is found that variable height microchannels heat sinks (VHMCHS) approach mitigates flow maldistribution rapidly in comparison to variable width microchannels heat sinks (VWMCHS) approach, almost 50% computational time can be saved by VHMCHS approach. Average fluid–solid interface temperature fluctuation across parallel microchannels reduces 3.3 °C by VHMCHS in comparison to VWMCHS approach. The maximum and average temperatures of the base of the heat sink are further reduced by 5.1 °C and 2.7 °C, respectively, for the VHMCHS. It is found that overall heat transfer performance of the heat sink improves further by 3.8% and 5.1% for the VWMCHS and VHMCHS, respectively. The pressure drop penalty of the VHMCHS is found to be 7.2% higher than VWMCHS.
Modeling and Optimization of Creep Behavior of Ni-Based Superalloys GTD-111 and IN-738LC Using Central Composite Design
Authors: Ganji O. , Shadman A. R. , Sajjadi S. A.
Published: March 2019

In this study, the effects of temperature, stress, and type of materials and their interactions on the creep rate and rupture time were investigated by using central composite design (CCD). An experimental plan for CCD with two numerical factors, one categorical factor, and two levels was used to optimize the required number of experiments. Temperatures of 800 and 900 °C and stresses of 250 and 450 MPa were selected as factors for GTD-111 and IN-738LC superalloys, respectively. Experimental and numerical results showed that the main effects of factors and their interactions are significant on the creep rate and rupture time. Among all factors, the effects of temperature and stress dominated other factors. Moreover, it was indicated that the combination between temperature and stress is much more effective on creep rate response than on rupture time. The high creep rate and the low rupture time values were obtained at the highest stress and temperature for IN-738LC. With the same experimental condition, creep rate values were the most and rupture time values were the least for IN-738LC in comparison with GTD-111.
Four-Probe Measurement of Thermal Transport in Suspended Few-Layer Graphene With Polymer Residue
Authors: Ou Eric , Li Xun , Lee Sangyeop , Watanabe Kenji , Taniguchi Takashi , Shi Li
Published: March 2019

The presence of unknown thermal contact thermal resistance has limited prior two-probe thermal transport measurements of suspended graphene samples. Here, we report four-probe thermal transport measurements of suspended seven-layer graphene. By isolating the thermal contact resistance, we are able to attribute the observed reduced thermal conductivity primarily to polymeric residue on the sample instead of the contact thermal resistance, which resulted in ambiguity in the prior experimental studies of the effect of polymer reside. The extrinsic scattering rate due to the polymer residue is extracted from the measurement results based on a solution of the Peierls-Boltzmann phonon transport equation.
Flow Field Characterization and Visualization of Grid Fin Subsonic Flow
Authors: Tripathi Manish , Sucheendran Mahesh M. , Misra Ajay
Published: March 2019

Grid fins are unconventional control surfaces consisting of an outer frame supporting an inner grid of intersecting planar surfaces. Although afflicted with higher drag, these have been credited for their enhanced lifting characteristics at high angles of attack and high Mach numbers, alongside reduced hinge moments accounting for the recent upsurge in their usage on numerous aerospace applications. Present investigations carry out elaborate flow field visualization and characterization underlining the rudimentary physics through a sequence of subsonic numerical simulations performed at different angles of attack and different gap (between the members) to chord ratios on a simplified grid fin variant called cascade fin. The study makes use of a new nondimensionalization technique called cumulative nondimensionalization to decipher the effect of cascading on individual members of the fin. Hence, after a comprehensive examination of the aerodynamic coefficients, pressure coefficient distribution, pressure gradient, velocity gradient, boundary layer velocity profile, and flow field visualization, the study elucidates physics associated with hastened stall angle, augmented lift-drag, and bounded efficiency accretion for gap increment.
Micropitting Fatigue Wear Simulation in Conformal-Contact Under Mixed Elastohydrodynamic Lubrication
Authors: Jia Hang , Li Junyang , Wang Jiaxu , Xiang Guo , Xiao Ke , Han Yanfeng
Published: March 2019

In this study, a physics-based fatigue wear model is proposed to evaluate the reliability and to predict the life of cumulative micropitting wear for lubricated conformal contacts on rough surfaces. The surface normal load, mean film thickness, and frictional shear traction are simulated by a mixed elastohydrodynamic lubrication (EHL) model for a stress prediction model to calculate the average maximum Hertzian pressure of contact asperities and unit with the statistical contact model and dynamic contact model to obtain the asperity stress cycle number. The wear formula is established through combining a micropitting life prediction model of surface asperities and a mean micropitting damage constant of asperities. The four dominant aspects affecting wear behaviors of the surface contact pairs, working conditions, structure and surface topographies, material properties and lubrication conditions are all taken into account in the model. It is a high-fidelity and comprehensive model that can be used to analyze and optimize the tribological design of rolling–sliding pairs in machinery. The micropitting fatigue wear modeling scheme is validated by comparison of theoretical calculations and available experimental wear data.
Novel One-Component Anisole- and Hydroxyl-Terminated Perfluoropolyethers for Boundary Lubrication
Authors: Fan Ao , Wiita Connie , Waltman Robert J.
Published: March 2019

The tribological properties of some novel single component perfluoropolyether (PFPE) boundary lubricants with chemically integrated mixture end groups are investigated. Chemically integrated mixture end groups composed of hydroxyl- and anisole-terminated PFPE boundary lubricant films on the –(CF2CF2CF2O)– main chain are reported. These PFPE-based boundary lubricants explore a new method by which single component PFPE lubricants with mixture end groups might be used to tailor boundary film properties instead of using physical mixtures of two or more PFPEs with different end groups. Lubricant transfer to the low-flying read/write head, head wear, and siloxane adsorption as a function of PFPE film thickness and of type are compared. Normalization of the data to the monolayer fraction instead of film thickness allows direct comparison between anisole- and hydroxyl-terminated PFPEs. Lubricant transfer to the head and head wear are independent of the functional end groups. Siloxane adsorption decreases with increasing anisole substitution of the hydroxyl groups. One-component PFPEs with mixed end groups provide a methodology by which boundary film properties could be adjusted.
Experimental Analysis of Chromium Molybdenum Coatings Under Mixed Elastohydrodynamic Lubrication for Film Thickness, Friction, and Wear Characterizations
Authors: Pickens David , Liu Zhong , Nishino Takayuki , Wang Q. Jane
Published: March 2019

This research aims to evaluate the tribological performance of chromium molybdenum (CrMo) coatings under point and line-contact mixed elastohydrodynamic lubrication. This article studies the coatings made from two different methods and treated in an electrifying process of different durations, which produced microchannels and micropockets in the surfaces. The resulting surface topographies had varying impacts on lubricant film thickness, friction, and wear. Root-mean-square roughness (Sq) and porosity are used to characterize the surfaces and their performances in terms of film thickness, friction, and wear. The results suggest that the coated surfaces with a lower Sq and porosity density tended to yield higher film thickness. However, their influence on friction is complicated; lower roughness and porosity are preferred for lower wear, but certain levels of small roughness and surface pores may help to reduce boundary lubrication friction when compared with the frictional behaviors of porosity-free surfaces and those with higher roughness and higher porosity.
A Conforming Augmented Finite Element Method for Modeling Arbitrary Cracking in Solids
Authors: Ma Zhaoyang , Yang Qingda , Su Xianyue
Published: March 2019

This paper presents a conforming augmented finite element method (C-AFEM) that can account for arbitrary cracking in solids with similar accuracy of other conforming methods, but with a significantly improved numerical efficiency of about ten times. We show that the numerical gains are mainly due to our proposed new solving procedure, which involves solving a local problem for crack propagation and a global problem for structural equilibrium, through a tightly coupled two-step process. Through several numerical benchmarking examples, we further demonstrate that the C-AFEM is more accurate and mesh insensitive when compared with the original A-FEM, and both C-AFEM and A-FEM are much more robust and efficient than other parallel methods including the extended finite element method (XFEM)/generalized finite element (GFEM) and the conforming embedded discontinuity method.
Frequency of greatest temporary hearing threshold shift in harbor seals (Phoca vitulina) depends on fatiguing sound level
Authors: Kastelein Ronald A. , Helder-Hoek Lean , Gransier Robin
Published: March 2019

Harbor seals may suffer hearing loss due to intense sounds. After exposure for 60 min to a continuous 6.5 kHz tone at sound pressure levels of 123–159 dB re 1 µPa, resulting in sound exposure levels (SELs) of 159–195 dB re 1 μPa2s, temporary threshold shifts (TTSs) in two harbor seals were quantified at the center frequency of the fatiguing sound (6.5 kHz) and at 0.5 and 1.0 octaves above that frequency (9.2 and 13.0 kHz) by means of a psychoacoustic technique. Taking into account the different timing of post-exposure hearing tests, susceptibility to TTS was similar in both animals. The higher the SEL, the higher the TTS induced at frequencies above the fatiguing sound's center frequency. Below ∼179 dB re 1 μPa2s, the maximum TTS was at the center frequency (6.5 kHz); above ∼179 dB re 1 μPa2s, the maximum TTS was at half an octave above the center frequency (9.2 kHz). These results should be considered when interpreting previous TTS studies, and when estimating ecological impacts of anthropogenic sound on the hearing and ecology of harbor seals. Based on the results of the present study and previous studies, harbor seal hearing, in the frequency range 2.5–6.5 kHz, appears to be approximately equally susceptible to TTS.
The percept of reverberation is not affected by visual room impression in virtual environments
Authors: Schutte Michael , Ewert Stephan D. , Wiegrebe Lutz
Published: March 2019

Humans possess mechanisms to suppress distracting early sound reflections, summarized as the precedence effect. Recent work shows that precedence is affected by visual stimulation. This paper investigates possible effects of visual stimulation on the perception of later reflections, i.e., reverberation. In a highly immersive audio-visual virtual reality environment, subjects were asked to quantify reverberation in conditions where simultaneously presented auditory and visual stimuli either match in room identity, sound source azimuth, and sound source distance, or diverge in one of these aspects. While subjects reliably judged reverberation across acoustic environments, the visual room impression did not affect reverberation estimates.
A gastric resident drug delivery system for prolonged gram-level dosing of tuberculosis treatment
Authors: Verma Malvika , Vishwanath Karan , Eweje Feyisope , Roxhed Niclas , Grant Tyler , Castaneda Macy , Steiger Christoph , Mazdiyasni Hormoz , Bensel Taylor , Minahan Daniel , Soares Vance , Salama John A. F. , Lopes Aaron , Hess Kaitlyn , Cleveland Cody , Fulop Daniel J. , Hayward Alison , Collins Joy , Tamang Siddartha M. , Hua Tiffany , Ikeanyi Chinonyelum , Zeidman Gal , Mule Elizabeth , Boominathan Sooraj , Popova Ellena , Miller Jonathan B. , Bellinger Andrew M. , Collins David , Leibowitz Dalia , Batra Shelly , Ahuja Sandeep , Bajiya Manju , Batra Sonali , Sarin Rohit , Agarwal Upasna , Khaparde Sunil D. , Gupta Neeraj K. , Gupta Deepak , Bhatnagar Anuj K. , Chopra Kamal K. , Sharma Nandini , Khanna Ashwani , Chowdhury Jayeeta , Stoner Robert , Slocum Alexander H. , Cima Michael J. , Furin Jennifer , Langer Robert , Traverso Giovanni
Published: March 2019

A retrievable device, compatible with nasogastric tube administration, releases grams of drug over weeks while residing in the stomach.
The lymphatic route of TAU
Authors: Haigh Cathryn L.
Published: March 2019

The brain lymphatic system contributes to TAU clearance in mice.
Fate of CMY-2-Encoding Plasmids Introduced into the Human Fecal Microbiota by Exogenous
Escherichia coli
Authors: Anjum Mehreen , Madsen Jonas Stenløkke , Nesme Joseph , Jana Bimal , Wiese Maria , Jasinskytė Džiuginta , Nielsen Dennis Sandris , Sørensen Søren Johannes , Dalsgaard Anders , Moodley Arshnee , Bortolaia Valeria , Guardabassi Luca
Published: March 2019

The gut is a hot spot for transfer of antibiotic resistance genes from ingested exogenous bacteria to the indigenous microbiota. The objective of this study was to determine the fate of two nearly identical
bla
CMY-2
-harboring plasmids introduced into the human fecal microbiota by two
Escherichia coli
strains isolated from a human and from poultry meat.
A Novel 1,3-Beta-
d
-Glucan Inhibitor, Ibrexafungerp (Formerly SCY-078), Shows Potent Activity in the Lower pH Environment of Vulvovaginitis
Authors: Larkin E. L. , Long L. , Isham N. , Borroto-Esoda K. , Barat S. , Angulo D. , Wring S. , Ghannoum M.
Published: March 2019

Ibrexafungerp (IBX) (formerly SCY-078) is a novel glucan synthase inhibitor whose oral availability is being evaluated for efficacy against vulvovaginal candidiasis (VVC). Bioavailability and
in vitro
activity are important efficacy indicators, but accepted susceptibility methods do not always accurately predict activity in an acidic environment, such as the vagina.
Cell Aggregation and Aerobic Respiration Are Important for
Zymomonas mobilis
ZM4 Survival in an Aerobic Minimal Medium
Authors: Jones-Burrage Sara E. , Kremer Timothy A. , McKinlay James B.
Published: March 2019

The bacterium
Zymomonas mobilis
is best known for its anaerobic fermentative lifestyle, in which it converts glucose into ethanol at a yield surpassing that of yeast. However,
Z. mobilis
also has an aerobic lifestyle, which has confounded researchers with its attributes of poor growth, accumulation of toxic acetic acid and acetaldehyde, and respiratory enzymes that are detrimental for aerobic growth. Here we show that a major
Z. mobilis
respiratory enzyme and the ability to form multicellular aggregates, called flocs, are important for survival, but only during aerobic growth in a medium containing a minimum set of nutrients required for growth. Supplements, such as vitamins or yeast extract, promote aerobic growth and, in some cases, inhibit floc formation. We propose that
Z. mobilis
likely requires aerobic respiration and floc formation in order to survive in natural environments that lack protective factors found in supplements such as yeast extract.
Bacterial Analogs of Plant Tetrahydropyridine Alkaloids Mediate Microbial Interactions in a Rhizosphere Model System
Authors: Lozano Gabriel L. , Park Hyun Bong , Bravo Juan I. , Armstrong Eric A. , Denu John M. , Stabb Eric V. , Broderick Nichole A. , Crawford Jason M. , Handelsman Jo
Published: March 2019

The microbiomes of plants are critical to host physiology and development. Microbes are attracted to the rhizosphere due to massive secretion of plant photosynthates from roots. Microorganisms that successfully join the rhizosphere community from bulk soil have access to more abundant and diverse molecules, producing a highly competitive and selective environment. In the rhizosphere, as in other microbiomes, little is known about the genetic basis for individual species’ behaviors within the community. In this study, we characterized competition between
Pseudomonas koreensis
and
Flavobacterium johnsoniae
, two common rhizosphere inhabitants. We identified a widespread gene cluster in several
Pseudomonas
spp. that is necessary for the production of a novel family of tetrahydropyridine alkaloids that are structural analogs of plant alkaloids. We expand the known repertoire of antibiotics produced by
Pseudomonas
in the rhizosphere and demonstrate the role of the metabolites in interactions with other rhizosphere bacteria.