bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystal structures of 1-(4-chlorophenyl)-4-(4-methylphenyl)-2,5-dioxo-1,2,5,6,7,8-hexahydroquinoline-3-carboxylic acid and 4-(4-methoxyphenyl)-1-(4-methylphenyl)-2,5-dioxo-1,2,5,6,7,8-hexahydroquinoline-3-carbonitrile
Authors: Allah Omyma A. Abd , Kaur Manpreet , Akkurt Mehmet , Mohamed Shaaban K. , Tamam Asmaa H. A. , Elgarhy Sahar M. I. , Jasinski Jerry P.
Published: March 2021

In the title compounds C23H21ClN2O3 [I, namely 1-(4-chlorophenyl)-4-(4-methylphenyl)-3,8-dioxo-1,2,5,6,7,8-hexahydroquine-3-carboxylic acid] and C24H22N2O3 [II, namely 4-(4-methoxyphenyl)-1-(4-methylphenyl)-2,5-dioxo-1,2,5,6,7,8-hexahydroquinoline-3-carbonitrile], each of the cyclohexene and dihydropyridine rings of the 1,2,5,6,7,8-hexahydroquinoline moieties adopts a twisted-boat conformation. The asymmetric units of both compounds I and II consist of two independent molecules (A and B). In II
A, three carbon atoms of the cyclohexene ring are disordered over two sets of sites in a 0.670 (11):0.330 (11) occupancy ratio. In the crystal of I, molecules are linked through classical N—H...O hydrogen bonds, forming inversion dimers with an R
2
2(8) ring motif and with their molecular planes parallel to the crystallographic (020) plane. Non-classical C—H...O hydrogen-bonding interactions connect the dimers, resulting in a three-dimensional network. In the crystal of II, molecules are linked by C—H...N, C—H...O and C—H...π interactions, forming a three-dimensional network.
Crystal structure of tert-butyl 4-[4-(4-fluorophenyl)-2-methylbut-3-yn-2-yl]piperazine-1-carboxylate
Authors: Gumireddy Ashwini , DeBoyace Kevin , Rupprecht Alexander , Gupta Mohit , Patel Saloni , Flaherty Patrick T. , Wildfong Peter L. D.
Published: March 2021

The title sterically congested piperazine derivative, C20H27FN2O2, was prepared using a modified Bruylants approach. A search of the Cambridge Structural Database identified 51 compounds possessing an N-tert-butyl piperazine substructure. Of these only 14 were asymmetrically substituted on the piperazine ring and none with a synthetically useful second nitrogen. Given the novel chemistry generating a pharmacologically useful core, determination of the crystal structure for this compound was necessary. The piperazine ring is present in a chair conformation with di-equatorial substitution. Of the two N atoms, one is sp
3 hybridized while the other is sp
2 hybridized. Intermolecular interactions resulting from the crystal packing patterns were investigated using Hirshfeld surface analysis and fingerprint analysis. Directional weak hydrogen-bond-like interactions (C—H...O) and C—H...π interactions with the dispersion interactions as the major source of attraction are present in the crystal packing.
Crystal structure and Hirshfeld surface analysis of 4-(4-chlorophenyl)-5-methyl-3-{4-[(2-methylphenyl)methoxy]phenyl}-1,2-oxazole
Authors: Aydin Abdullah , Akkurt Mehmet , Turanli Sumeyye , Lengerli Deniz , Banoglu Erden , Ozcelik Nefise Dilek
Published: March 2021

In the title compound, C24H20ClNO2, the mean planes of 4-chlorophenyl, 2-methylphenyl and phenylene rings make dihedral angles of 62.8 (2), 65.1 (3) and 15.1 (2)°, respectively, with the 5-methyl-1,2-oxazole ring. In the crystal, molecules are linked by intermolecular C—H...N, C—H...Cl, C—H...π contacts and π–π stacking interactions between the phenylene groups. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (48.7%), H...C/C...H (22.2%), Cl...H/H...Cl (8.8%), H...O/O...H (8.2%) and H...N/N...H (5.1%) interactions.
Researchers’ awareness about plagiarism and impact of plagiarism detection tools – does awareness effect the actions towards preventing plagiarism?
Authors: Mostofa Sk. Mamun , Tabassum Mashiat , Ahmed S.M. Zabed
Published: March 2021

Purpose

This paper aims to analyse researchers’ awareness about plagiarism and impact of plagiarism detection tools on the actions that they take to prevent plagiarism. It also employs a structural model that examines whether awareness of plagiarism and anti-plagiarism tools have any significant effect on the actions taken by the researchers to avoid plagiarism.

Design/methodology/approach

A survey questionnaire was distributed to researchers at a large public university in Bangladesh. The survey accumulated 184 valid responses. Descriptive statistics were obtained to assess researchers’ awareness about plagiarism and impact of plagiarism detection tools and the actions taken by them. The reasons that may cause plagiarism were also identified. The awareness of the availability of the anti-plagiarism software that was being used by the university and its actual use by the researchers was gathered through the survey. Non-parametric Mann–Whitney and Kruskal–Wallis tests were conducted to investigate the differences in awareness levels and actions in terms of gender, age, discipline and current level of research. The chi-square test was carried out to examine the relationship between awareness about the availability of the anti-plagiarism software and its use by the researchers. Finally, the survey data were analysed using structural equation modeling to examine the effects of awareness of plagiarism and anti-plagiarism software on the actions taken by the researchers.

Findings

The study revealed that the level of awareness regarding plagiarism and impact of plagiarism detection software is generally high among the researchers. There are some significant differences between researchers’ demographic and personal characteristics and their awareness levels and actions with regard to plagiarism. The findings indicate that almost three-quarters of the researchers were aware about the anti-plagiarism tool that is being used, whereas more than half of the researchers indicated that they used the software to assess their works. The results of the structural equation model do not show a good fit, although there is strong statistical evidence that awareness about plagiarism and anti-plagiarism software has significantly impacted researchers’ actions towards preventing plagiarism.

Originality/value

There is no reported study on researchers’ awareness of plagiarism and its affiliated issues in Bangladesh. The findings of this study will not only provide useful insights regarding awareness about plagiarism but also assist university authorities to formulate relevant policy and take necessary actions against plagiarism in higher education institutions.
Real‐world prevalence and burden of genital eczema in atopic dermatitis: A multicenter questionnaire‐based study
Authors: Woo Yu Ri , Han Yujin , Lee Ji Hae , Lee Young Bok , Kim Jung Eun , Kim Miri , Park Chul Jong , Lee Ji Hyun , Cho Sang Hyun
Published: March 2021

The involvement of genital lesions in patients with atopic dermatitis (AD) is poorly understood. Moreover, clinical characteristics, potentially related factors, and impact on the quality of life (QOL) of genital eczema in patients with AD are also largely unknown. This study aims to evaluate the prevalence and burden of genital eczema in patients with AD. A prospective cross‐sectional study recruited a total of 220 patients diagnosed with AD. The participants were asked to complete the self‐administrated questionnaire asking sociodemographic characteristics, details about their AD, and individual experiences of their genital eczema. Among 220 responders, 99 patients (45.00%) reported that they had experienced genital eczema at some time during the course of AD. Longer disease duration (odds ratio [OR], 2.29; 95% confidence interval [CI], 1.13–4.62; p = 0.02), marital status (OR, 0.43; 95% CI, 0.21–0.89; p = 0.003), involvement of the trunk (OR, 3.44; 95% CI, 1.81–6.52; p = 0.001), and involvement of the nipple (OR, 6.20; 95% CI, 1.39–27.63; p = 0.017) were the significant associated factors for the presence of genital eczema among patients with AD. Of note, the severe impairment of genital eczema‐specific QOL was observed in 28.29% of AD patients with genital eczema. Especially, female sex (OR, 2.22; 95% CI, 0.84–5.82; p = 0.04) was more associated with severe impairment of genital eczema‐specific QOL. Many patients with AD suffer from the genital presentation of the disease. Moreover, genital involvement of the disease has a significant impact on the QOL of patients with AD. We suggest that more attention should be paid to the genital presentation of the disease to increase QOL and provide further delicate treatment of patients with AD.
Do Analysts Account for Accruals? Evidence from the Insurance Industry*
Authors: Baik Bok , Kim Young Jun , Roh Yongoh
Published: March 2021

Property‐casualty (PC) insurers are mandated by the Securities and Exchange Commission (SEC) to report managers’ revisions of loss reserve estimates (“development”) in 10‐K supplemental disclosures. Using manually collected PC insurers’ development, we examine whether analysts’ earnings forecasts incorporate information in development. We initially show that development has incremental power to predict insurers’ future profitability. Although analysts revise earnings forecasts in response to the updates on development in 10‐K filings, their forecast errors are positively related to development. We also find that analysts exhibit greater errors for firms that exert more discretion over development. Overall, our findings suggest that analysts do not fully incorporate the information in managers’ estimates.
Predictive biomarkers and clinical evidence
Authors: Jørgensen Jan Trøst
Published: March 2021

Predictive biomarkers play an important role in our efforts to individualize pharmacotherapy, and within recent years, a number of different types of assays have been introduced. These biomarkers may potentially support the selection and dosage of specific drugs in order to maximize efficacy and minimize adverse reactions in the individual patient. However, in many instances, the scientific and clinical evidence is insufficient to support the prescribing decision. When predictive biomarkers are used to guide pharmacotherapy, it is important to secure that decisions are based on solid clinical evidence. Here, the regulatory authorities, especially the FDA, have been at the forefront in relation to regulate this type of biomarker assay in order to secure patient safety. The approval process for companion diagnostics is an example of this effort, where the scientific validity of the biomarker and assay is in focus. With the approaching implementation of the new IVD Regulation, greater attention will also be paid to analytical and clinical validity of biomarker assays in the EU. For any type of predictive biomarker assay, including pharmacogenetic and tumour profiling tests, the clinical evidence needs to be in place before they are used routinely in the clinic.
The feminist economic geographies of working from home and “digital by default” in Canada before, during, and after COVID‐19
Authors: Cockayne Daniel
Published: March 2021

This paper builds on insights in feminist economic geography to critically review the literature on work in the home and provide a starting point for examining COVID‐19 pandemic‐imposed work from home measures for tertiary and quaternary sector firms and organizations. It critically reviews literature on the pandemic, working from home, and work in general, to examine lockdown‐related workplace disruptions in relation to the various forms of work that took place in the home prior to the pandemic. It argues that feminist economic geography provides a starting point for examinations of working from home during and after COVID‐19. This situates writing on social reproduction, and informal and unpaid work in the home, within the purview of our understanding of pandemic response. Following this review, the paper demonstrates this argument by interrogating Canada's “telework capacity” discourse and the decisions by white‐collar offices regarding the continuation and abatement of “digital by default” policies. The pandemic will radically shift our understanding of the meanings of both home and work, and this paper, through a critical review of key literature, suggests that feminist economic geography provides one starting point for theorizing the implications of that shift in the Canadian context.
Transepithelial corneal collagen cross‐linking using iontophoresis versus the Dresden protocol in progressive keratoconus: A meta‐analysis
Authors: Wan Kelvin H. , Ip Christina K. Y. , Kua Wee Nie , Chow Vanissa W. S. , Chong Kelvin K. L. , Young Alvin L. , Cheng George P. M. , Jhanji Vishal
Published: March 2021

Background

Standard epithelium‐off collagen cross‐linking using Dresden protocol (S‐CXL) is the standard of care for progressive keratoconus. Despite its efficacy, epithelial debridement is associated with pain, delayed visual rehabilitation, stromal oedema and haze. Minimising these complications while achieving a comparable efficacy remains an unmet need.

Methods

Comparative studies between transepithelial iontophoresis‐assisted CXL (I‐CXL) and S‐CXL reporting the outcomes of visual, refractive, topographic, aberrometry, demarcation line, endothelial cell density, confocal microscopy or complications were identified from databases. Assessments of publication bias, meta‐analyses, sensitivity analysis, subgroup analysis, and meta‐regressions were performed.

Results

In this meta‐analysis, 586 eyes from three randomised controlled trials and seven comparative studies were analysed. No differences were found in the change in uncorrected/corrected distance visual acuities, mean/maximum keratometry, central corneal thickness, higher order aberration, spherical aberration, coma, subbasal nerve/anterior stromal keratocyte density and demarcation line depth in both CXL protocols (P ≥ .052). However, I‐CXL resulted in less thinning at the minimum pachymetry (standardised mean difference 0.25; 95% confidence interval [CI] 0.06‐0.44). More importantly, there was a significant reduction in complications following I‐CXL (odds ratio 0.30; 95% CI 0.12‐0.75). Meta‐regression analyses on demarcation line depth and complication suggested that I‐CXL was more effective than S‐CXL when baseline maximum keratometry was >55.2 D and the risk of complication was independent of other baseline covariates.

Conclusion

I‐CXL has a more favourable safety profile, as evidenced by the available literature, with less thinning at the minimum pachymetry and reduced risk of complications while achieving comparable effects on visual, refractive, topographic, aberrometry, and morphological outcomes as S‐CXL.
Automated seizure detection using wearable devices: A clinical practice guideline of the International League Against Epilepsy and the International Federation of Clinical Neurophysiology
Authors: Beniczky Sándor , Wiebe Samuel , Jeppesen Jesper , Tatum William O. , Brazdil Milan , Wang Yuping , Herman Susan T. , Ryvlin Philippe
Published: March 2021

The objective of this clinical practice guideline (CPG) is to provide recommendations for healthcare personnel working with patients with epilepsy on the use of wearable devices for automated seizure detection in patients with epilepsy, in outpatient, ambulatory settings. The Working Group of the International League Against Epilepsy (ILAE) and the International Federation of Clinical Neurophysiology (IFCN) developed the CPG according to the methodology proposed by the ILAE Epilepsy Guidelines Working Group. We reviewed the published evidence using The Preferred Reporting Items for Systematic Review and Meta‐Analysis (PRISMA) statement and evaluated the evidence and formulated the recommendations following the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. We found high level of evidence for the accuracy of automated detection of generalized tonic‐clonic seizures (GTCS) and focal‐to‐bilateral tonic‐clonic seizures (FBTCS) and recommend the use of wearable automated seizure detection devices for selected patients when accurate detection of GTCS and FBTCS is recommended as a clinical adjunct. We also found a moderate level of evidence for seizure types without GTCS or FBTCS. However, it was uncertain whether the detected alarms resulted in meaningful clinical outcomes for the patients. We recommend using clinically validated devices for automated detection of GTCS and FBTCS, especially in unsupervised patients, where alarms can result in rapid intervention (weak/conditional recommendation). At present, we do not recommend clinical use of the currently available devices for other seizure types (weak/conditional recommendation). Further research and development are needed to improve the performance of automated seizure detection and to document their accuracy and clinical utility.
Writing an effective and supportive recommendation letter
Authors: Sarabipour Sarvenaz , Hainer Sarah J. , Furlong Emily , Jadavji Nafisa M. , de Winde Charlotte M. , Bielczyk Natalia , Shah Aparna P.
Published: March 2021

Writing recommendation letters on behalf of students and other early‐career researchers is an important mentoring task within academia. An effective recommendation letter describes key candidate qualities such as academic achievements, extracurricular activities, outstanding personality traits, participation in and dedication to a particular discipline, and the mentor’s confidence in the candidate's abilities. In this Words of Advice, we provide guidance to researchers on composing constructive and supportive recommendation letters, including tips for structuring and providing specific and effective examples, while maintaining a balance in language and avoiding potential biases.
Impact of delay in follow‐up due to COVID‐19 pandemic on skin cancer progression: a real‐life experience from an Italian hub hospital
Authors: Valenti Mario , Pavia Giulia , Gargiulo Luigi , Facheris Paola , Nucca Ombretta , Mancini Luca , Sacrini Francesco , Borroni Riccardo G. , Narcisi Alessandra , Costanzo Antonio
Published: March 2021

Background

The COVID‐19 pandemic required the setting of a national lockdown in Italy from March 9, 2020, until May 18, 2020; therefore, most of the non‐COVID‐19 activities were postponed. As a consequence, many follow‐up visits in patients with previously excised skin cancers were delayed. The aim of this retrospective real‐life case–control study is demonstrating that delay in follow‐up led to an increased incidence of advanced melanoma and keratinocyte cancers on the total of surgically excised skin cancers.

Methods

The incidence of excised advanced melanoma and keratinocyte cancers in our dermato‐surgery division in the period May 18 to November 18, 2020, was compared to the same time span of 2019. All data were collected from the electronic database of our department. Odds ratio with 95% confidence interval was used to assess the risk of excised advanced skin cancers in 2020 compared to 2019.

Results

From May to November 2019, we performed 265 surgical excisions, while during the pandemic in 2020, we completed 280 surgeries. The number of advanced skin cancers excised between May 18 and November 18, 2020, was significantly higher compared with the same period in 2019 (54 vs. 22, OR: 2.64; 95% CI: 1.56–4.47; P = 0.0003). Significant differences were also observed regarding the number of surgically removed advanced BCCs (OR 2.15; 95% CI 1.14–4.07; P = 0.0187) and advanced SCCs (OR 4.60; 95% CI 1.31–16.18; P = 0.0175).

Conclusion

These results confirm that delay in follow‐up and, consequently, postponed surgical excisions are related to an increased incidence of advanced skin tumors, resulting in poorer prognosis lifelong. Follow‐up visits should be carried on even during COVID‐19 pandemic, avoiding significant delays as much as possible.
Inhibition of hypertrophic scar formation with oral asiaticoside treatment in a rabbit ear scar model
Authors: Huang Jia , Zhou Xiaobo , Xia Lingling , Liu Weiwei , Guo Fei , Liu Jianhui , Liu Wei
Published: March 2021

Hypertrophic scar (HS) is a fibrotic skin disease characterised by over‐productive collagen and excessive inflammatory reaction, which can be functionally and cosmetically problematic. A scar‐prone constitute will accelerate HS formation and functional disorder, which deserves systemic therapy with oral medicine. To examine the oral therapeutic effectiveness on HS with convincing evidence of gross view and histological improvement, a rabbit ear HS model was employed with oral administration of asiaticoside (AS) at the doses of 12 and 24 mg kg−1 d−1 daily for 60 consecutive days. Gross observation and histological findings showed that oral AS treatment could significantly inhibit HS formation in a dose dependent manner. Semi‐quantification of scar elevation index at days 7, 15, 30, and 60, and quantitative polymerase chain reaction at days 30 and 60 also provided the evidences of reduced scar thickness and inhibited fibrotic gene expressions of collagens I, III, TGF‐β1, interleukins 1β, 6 and 8, and enhanced gene expression of SMAD 7 and PPAR‐γ with a dose‐dependent manner. These results indicated that AS is likely to serve as a systemic therapeutic agent of HS treatment for those who may have scar‐prone constitute via anti‐inflammation, inhibiting fibrotic process, and enhancing matrix degradation.
Whose resilience matters? Addressing issues of scale in supply chain resilience
Authors: Novak David C. , Wu Zhaohui , Dooley Kevin J.
Published: March 2021

Many existing studies and models of supply chain resilience conceptualize resilience from the perspective of an equilibrium‐seeking focal firm or industry. The term “supply chain resilience” is often discussed as a dimension of firm resilience, as opposed to a standalone concept. In this context, resilience is defined according to how well a firm or industry can respond to a disruption while maintaining existing structures and processes and then “bounce back” to a pre‐disruption equilibrium or “bounce forward” to a new, presumably better, equilibrium in the shortest amount of time with the least cost. In this paper, we argue that equilibrium‐based conceptualizations of supply chain resilience can be misaligned with the notion of a supply chain as complex adaptive system (CAS) that continually adapts and transforms via autonomous actions of the different actors within the system. We offer suggestions on how practitioners and researchers can advance theory and practice by adopting a CAS or complexity‐based perspective on supply chain resilience. Specifically, we address the importance of scale and the challenges associated with mismatched scales.
Electrical conductivity and performance evaluation of verjuice concentration process using ohmic heating method
Authors: Cevik Mutlu
Published: March 2021

The verjuice sample (14.5 ± 0.2% total soluble solid [TSS] content) was concentrated (at 102 ± 2°C evaporation temperature) until reach 50% TSS content by applying ohmic heating at 13, 15, 17, and 19 V/cm voltage gradients. The total process times up to 50% TSS content were determined as 2,100, 1,500, 1,200, and 1,020 s for 13, 15, 17, and 19 V/cm, respectively. The electrical conductivity values increased until reach 32% TSS content and then showed a decrease until the final TSS content. The total energy consumption values increased as the voltage gradient decreased. The total power and specific water removal ratio (SWRR) values decreased as the voltage gradient decreased. The efficiency of ohmic heating assisted concentration process increased with the applied voltage gradient and it ranged from 71.27 to 75.22%. By evaluating the effects of ohmic heating conditions applied in the present study on total process time, total energy consumption, and process efficiency, 19 V/cm voltage gradients could be recommended to be optimum evaporation conditions of verjuice concentration in case of decreasing process time and higher energy efficiency.

Practical applications

Fruit juices are generally concentrated to extend their shelf life. Therefore, for concentration purposes, various techniques, such as thermal evaporation, freezing methods, and membrane techniques, are applied in the fruit juice industry. This technique has some disadvantages, such as high energy requirements, the formation of undesirable compounds, high initial investment cost, and high failure rate to reach the desired total soluble solid content. The ohmic heating method, which is among the alternative heating methods, has advantages such as high energy efficiency, shorter processing time, higher product quality, and not causing wastewater. As a result of this study, it is thought that the verjuice samples were successfully concentrated up to 50% TSS content by using the ohmic heating method and this method can be used as an alternative method instead of the traditional method due to higher process efficiency and shorter process time.
Proopiomelanocortin deficiency diagnosed in infancy in two boys and a review of the known cases
Authors: Graves Lara E. , Khouri Joseph M. , Kristidis Peter , Verge Charles F.
Published: March 2021

Proopiomelanocortin (POMC) deficiency is a rare monogenic disorder characterised by adrenocorticotropic hormone (ACTH) deficiency, red hair and hyperphagic obesity. Two unrelated cases presented with hypoglycaemia due to isolated ACTH deficiency in the neonatal period. POMC deficiency was suspected at age 2 years (c.133‐2A>C) and at age 9 months (c.64del) due to infantile hyperphagic obesity. Neither patient had a convincing red hair phenotype at the time of diagnostic suspicion, illustrating the importance of suspecting POMC deficiency in isolated ACTH deficiency. Both patients have normal psychomotor development, whereas the only other reported case of c.64del had significant delay. This suggests, if ACTH deficiency is treated early in the neonatal period, that psychomotor retardation is not a part of the phenotype. We review 24 reported cases of POMC deficiency published to date. Although there is no current specific treatment for obesity in POMC deficiency, we anticipate that setmelanotide may be a useful future treatment option.
Melatonin promotes potassium deficiency tolerance by regulating HAK1 transporter and its upstream transcription factor NAC71 in wheat
Authors: Li Ge‐Zi , Liu Jin , Chen Shi‐Juan , Wang Peng‐Fei , Liu Hai‐Tao , Dong Jie , Zheng Yong‐Xing , Xie Ying‐Xin , Wang Chen‐Yang , Guo Tian‐Cai , Kang Guo‐Zhang
Published: March 2021

Melatonin (MT) is involved in various physiological processes and stress responses in animals and plants. However, little is known about the molecular mechanisms by which MT regulates potassium deficiency (DK) tolerance in crops. In this study, an appropriate concentration (50 μmol/L) was found to enhance the tolerance of wheat plants against DK. RNA‐seq analysis showed that a total of 6253 and 5873 differentially expressed genes (DEGs) were separately identified in root and leaf tissues of the DK + MT‐treated wheat plants. They functionally involved biological processes of secondary metabolite, signal transduction, and transport or catabolism. Of these, an upregulated high‐affinity K transporter 1 (TaHAK1) gene was next characterized. TaHAK1 overexpression markedly enhanced the K absorption, while its transient silencing exhibited the opposite effect, suggesting its important role in MT‐mediated DK tolerance. Moreover, yeast one‐hybrid (Y1H) was used to screen the upstream regulators of TaHAK1 gene and the transcription factor TaNAC71 was identified. The binding between TaNAC71 and TaHAK1 promoter was evidenced by using Y1H, LUC, and EMSA assays. Transient overexpression of TaNAC71 in wheat protoplasts activated the TaHAK1 expression, whereas its transient silencing inhibited the TaHAK1 expression and aggravated the sensitivity to DK. Exogenous MT application greatly upregulated the expression of TaHAK1 in both transient overexpression and silencing systems. Our findings revealed some molecular mechanisms underlying MT‐mediated DK tolerance and helped broaden its practical application in agriculture.
Unravelling foliar water uptake pathways: The contribution of stomata and the cuticle
Authors: Guzmán‐Delgado Paula , Laca Emilio , Zwieniecki Maciej A.
Published: March 2021

Plants can absorb water through their leaf surfaces, a phenomenon commonly referred to as foliar water uptake (FWU). Despite the physiological importance of FWU, the pathways and mechanisms underlying the process are not well known. Using a novel experimental approach, we parsed out the contribution of the stomata and the cuticle to FWU in two species with Mediterranean (Prunus dulcis) and temperate (Pyrus communis) origin. The hydraulic parameters of FWU were derived by analysing mass and water potential changes of leaves placed in a fog chamber. Leaves were previously treated with abscisic acid to force stomata to remain closed, with fusicoccin to remain open, and with water (control). Leaves with open stomata rehydrated two times faster than leaves with closed stomata and attained approximately three times higher maximum fluxes and hydraulic conductance. Based on FWU rates, we propose that rehydration through stomata occurs primarily via diffusion of water vapour rather than in liquid form even when leaf surfaces are covered with a water film. We discuss the potential mechanisms of FWU and the significance of both stomatal and cuticular pathways for plant productivity and survival.
Seasonality of distinct respiratory viruses in a tropical city: implications for prophylaxis
Authors: Santos Ruth‐Kelly O. , Borges Igor C. , Souza Mariana L. , Bouzas Maiara L. , Nascimento‐Carvalho Cristiana M.
Published: March 2021

Objective

The frequency and seasonality of viruses in tropical regions are scarcely reported. We estimated the frequency of seven respiratory viruses and assessed seasonality of respiratory syncytial virus (RSV) and influenza viruses in a tropical city.

Methods

Children (age ≤ 18 years) with acute respiratory infection were investigated in Salvador, Brazil, between July 2014 and June 2017. Respiratory viruses were searched by direct immunofluorescence and real‐time polymerase chain reaction for detection of RSV, influenza A virus, influenza B virus, adenovirus (ADV) and parainfluenza viruses (PIV) 1, 2 and 3. Seasonal distribution was evaluated by Prais–Winsten regression. Due to similar distribution, influenza A and influenza B viruses were grouped to analyse seasonality.

Results

The study group comprised 387 cases whose median (IQR) age was 26.4 (10.5–50.1) months. Respiratory viruses were detected in 106 (27.4%) cases. RSV (n = 76; 19.6%), influenza A virus (n = 11; 2.8%), influenza B virus (n = 7; 1.8%), ADV (n = 5; 1.3%), PIV 1 (n = 5; 1.3%), PIV 3 (n = 3; 0.8%) and PIV 2 (n = 1; 0.3%) were identified. Monthly count of RSV cases demonstrated seasonal distribution (b3 = 0.626; P = 0.003). More than half (42/76 [55.3%]) of all RSV cases were detected from April to June. Monthly count of influenza cases also showed seasonal distribution (b3 = −0.264; P = 0.032). Influenza cases peaked from November to January with 44.4% (8/18) of all influenza cases.

Conclusions

RSV was the most frequently detected virus. RSV and influenza viruses showed seasonal distribution. These data may be useful to plan the best time to carry out prophylaxis and to increase the number of hospital beds.
Multidisciplinary Analysis and Optimization of Discrete Problems Using Response Surface Methods
Authors: Korngold Jacob C. , Gabriele Gary A.
Published: March 2021

The objective of this paper is to present a new algorithm to efficiently optimize multidisciplinary, coupled non-hierarchic systems with discrete variables. The algorithm decomposes the system into contributing disciplines, and uses designed experiments within the disciplines to build local response surface approximations to the discipline analysis. First and second order Global Sensitivity Equations are formulated and approximated by experimental data to build approximations to the global design space. The global approximation is optimized using branch and bound or simulated annealing. Convergence is rapid for systems with near quadratic behavior. The algorithm is demonstrated on a unique multidisciplinary learning tool, the Design and Manufacturing Learning Environment. This environment provides multimedia simulation for product life cycle disciplines, including design, manufacturing, marketing, and sales.
Finite Element Dynamic Modeling of Elastic Beam With Prismatic Joint
Authors: Al-Bedoor B. O. , Khulief Y. A.
Published: March 2021

A finite element dynamic model of a translating beam through a prismatic joint is presented. The method adopts a fixed number of elements. The element length, on the contrary to the previously reported models, is constant. The time dependent nature of the boundary conditions is utilized to impose the prismatic joint constraints by varying the stiffness of the transition element. This method preserves all the dynamic coupling terms between the axial rigid body motion and the elastic deformations. The end mass dynamics is conveniently considered in the formulation. Furthermore, the introduced dynamic model offers a convenient formulation that can be incorporated into a general flexible multibody dynamics code and lends itself for control applications. The developed model is evaluated through comparisons with previously reported results of other models.
On Computing Exact Gradients for Rigid Body Guidance Using Screw Parameters
Authors: Bobrow James E. , Park Frank C.
Published: March 2021

The problem of designing a mechanism that comes closest to reaching a desired set of goal positions is examined in this paper. The approach is first applied to spherical four-bar mechanism design synthesis on SO(3), and then extended to general spatial problems on SE(3). For each class of problems, we define a distance metric which is used in a numerical optimization algorithm to determine the optimum design. An important feature of our approach is that analytic gradients of the distance metric are determined in a straightforward manner which can be easily programmed. Once these gradients are known, general purpose optimization packages can efficiently compute locally optimal solutions with excellent convergence properties.
A New Model-Based Tool for Fault Detection and Isolation in Machine- and Rotordynamics
Authors: Söffker Dirk
Published: March 2021

Reliability and safety aspects are becoming much more important due to higher quality requirements, complicated and/or connected processes. The fault monitoring systems to be commonly used in machine- and rotordynamics are based on signal analysis methods. Furthermore, various kinds of fault detection and isolation (FDI)-schemes are already applied to a lot of technical applications of detecting and isolating sensor and actuator failures (Isermann, 1994; van Schrick, 1994) and also to fault detection in power plants (in general) or in manufacturing machines. An implicit assumption is that process or machine changes due to faults lead to changes in calculated parameters, which are unique and unambiguous. In the case of applying methods of signal analysis this means spectrums etc. the vibration behaviour will be monitored very well but have to be interpreted. On the other hand signal parameters usually only describe the system by analyzing output signals without use of known and unknown inner parameters and/or inputs. These parameters are available, and normally this knowledge is used by the operating staff interpreting the resulting signal parameters. In this way a decision-making problem appears so that questions about the physical character of faults, about the existence of special faults and also about the location of failures/faults has to be answered. In this way the experience and knowledge of the interpreting persons are very important. In this contribution the problems of the decision-making process are tried to defuse:

• The available knowledge about the unfaulty system parameters is used to built up beside a nominal system model an unambiguous fault-specific ratio. Inner states of the structure are estimated by an PI-observer.

• The developed robust PI-observer (Söffker et al., 1993a; Söffker et al., 1995a) estimates inner states and unknown inputs.

In (Söffker et al., 1993b) this new method is applied to the crack detection of a rotor, but not proved. In this paper the proof is given and a generalization is described. The advantages in contrast to usual signal based vibration monitoring systems and also modern FDI-schemes are shown.
Trade-Offs in Robust Design: Comparing Optimization, Taguchi’s Approach and Guided Iteration in Three Examples
Authors: Orelup Mark , Dixon John R.
Published: March 2021

The goal of designing for robustness is to produce products, parts, and sub-assemblies that exhibit minimal variation in performance over their lifetime despite variations in their manufacture and operating environment. Achieving both good performance and high robustness is inherently a multi-objective problem. In this paper, three methods for solving this problem (optimization, Taguchi’s approach, and guided iteration using Dominic3) are compared in three case studies. The ability of the methods to respond to different trade-offs between robustness and performance is examined and compared.
A Computer-Based Approach Towards Including Design History Information in Product Models and Function-Means Trees
Authors: Malmqvist Johan
Published: March 2021

This paper describes a computer-based approach towards design history documentation. The approach is based on design theory, more specifically on the “function-means tree” model of the design process and on the “chromosome” model for product modelling.

The realization of this concept requires that a more precise terminology is utilized when developing the function-means tree. In the paper, a number of extensions of the function-means tree terminology are suggested. These include using a wider definition of the function concept, representation of design rationale, constraints and objectives in the tree, and more refined concepts for decomposition of functions and functional requirements.

Preliminary tests of the system have demonstrated the feasibility of the approach. Further tests, based on design problems with more degrees of freedom are needed, to fully assess all aspects of the system, especially concerning the management of constraints and objectives in the extended function-means tree model.
A Taxonomy for Classifying Engineering Decision Problems and Support Systems
Authors: Ullman David G. , D’Ambrosio Bruce
Published: March 2021

The design of even the simplest product requires thousands of decisions. Yet very few of these decisions are supported with methods on paper or on computers. Is this because engineering design decisions don’t need support or is it because techniques have yet to be developed that are usable on a wide basis? In considering this question a wide range of decision problem characteristics need to be addressed. In engineering design some decisions are made by individuals, others by teams — some are about the product and others about the processes that support the product — some are based on complete, consistent, quantitative data and others on sparse, conflicting, qualitative discussions. In order to address the reasons why so little support is used and the characteristics of potentially useful decision support tools, a taxonomy of decision characteristics is proposed.1 This taxonomy is used to classify current techniques and to define the requirements for an ideal engineering design decision support system.
Design for Injection Molding: Balancing Mechanical Requirements, Manufacturing Costs, and Material Selection
Authors: Beiter Kurt A. , Cardinal James M. , Ishii Kos
Published: March 2021

This paper describes a procedure for considering mechanical requirements, manufacturing costs, and material selection in the design of injection molded parts. The benefit of this approach is the simultaneous consideration of the implications of material selection and part geometry on estimated manufacturing cost during candidate design selection. The current implementation uses the allowable deflection of a flat plate as an example performance measure. Manufacturability concerns include required part thickness and gating scheme to adequately mold the part, and a resulting cycle time based on part cooling time estimates. Part manufacturing cost includes material cost, cycle time, and production costs. A PC-based and CAD-integrated program illustrate our proposed procedure.
Virtual Prototyping of Die Design Algorithmic, Computational and Practical Considerations
Authors: Wuerger David , Gadh Rajit
Published: March 2021

This paper presents the implementation of the algorithms used for computing the die-open directions for a near-net-shape manufactured part, using the approach described in part one of this publication (Virtual Prototyping of Die Design - Theory and Formulation). In this approach, a set of concavity features is used to determine the die-open directions for a given part, first by determining the convex hull of the geometry, then by performing a boolean subtraction between the convex hull of the part and the 3-Dimensional solid model of the original part geometry. This will provide the set of concavity features that restrict the possible die-open directions for the part. A set of possible die-open directions is determined for each concavity feature. Subsequently, the set of directions common to all concavity features is determined to be the set of die-open directions for the part. The convex hull of a part (or a convex part) has unrestricted draw, implying that a convex part can be oriented in any fashion inside a die. The algorithms for this approach, its computational analysis, and strengths and weaknesses of the implementation are discussed in the current paper.
Modeling Contact/Impact in Hybrid Parameter Multiple Body Mechanical Systems: Extensions for Higher Order Continuum Models
Authors: Barhorst Alan A.
Published: March 2021

In recent work the author presented a systematic formulation of hybrid parameter multiple body mechanical systems undergoing contact/impact motion. The method rigorously modeled all motion regimes of hybrid multiple body systems (i.e. free motion, contact/impact motion, and constrained motion), utilizing minimal sets of hybrid differential equations. The contact/impact regime was modeled via the idea of instantaneous non-holonomic constraint application. The technique previously presented did not include the possibility of continuum assumptions along the lines of Timoshenko beams, higher order plate theories, or rational theories considering intrinsic spin-inertia. In this paper, the above mentioned method is extended to include the higher order continuum assumptions which eliminates some of the continuum shortfalls from the previous work.
Vibration Control of a Beam Embedded With an Electrorheological Fluid
Authors: Selstad Tyler J. , Farhang Kambiz , Chelidze David
Published: March 2021

Electrorheological (ER) fluids are known to exhibit damping and stiffness properties which are highly dependent on the induced electrical field strength within the ER medium. Incorporation of ER fluid within a structural member then provides a means of stiffness and damping variation of the member. A structural member with embedded ER fluid is considered. Equations governing the axial and transverse motions of the member are reduced to a system of linear ordinary differential equations with time-varying coefficients. Application of the multiple time scales method results in amplitude-frequency relations. A control method is considered in which the effect of embedded ER fluid damping modulation using a simple harmonic excitation voltage on the parametric stability boundaries of the member is examined. Results indicate that the parametric stability boundaries can change effecting various modulation amplitudes and frequencies.
Optimization of Stochastic Multibody Systems
Authors: Eberhard Peter , Schiehlen Werner , Bestle Dieter
Published: March 2021

The multibody system approach is used for the investigation of mechanical systems with large motions, e.g. in vehicle dynamics and robotics. Important modules of a computer-aided tool proposed for analysis and optimization are filtering techniques and scalar optimization algorithms. Formfilters are used for the creation of stochastic exciations and criterion computations.

Typical properties of deterministic and stochastic scalar optimization algorithms with application to dynamic systems are presented and a hybrid deterministic-stochastic approach is proposed which combines the advantages of both algorithm types. An application to vehicle dynamics clarifies the optimization concept.
Maximum Entropy Closure for Nonlinear Stochastic Systems
Authors: Sobczyk Kazimierz , Trębicki Jerzy
Published: March 2021

The statistical moments of the response of nonlinear stochastic systems are governed by an infinite hierarchy of equations. In order to evaluate the most important low order moments suitable closure schemes are necessary. In this paper a non-Gaussian closure procedure is presented which is based on the maximum entropy principle developed recently by the authors in the context of stochastic nonlinear dynamics.
Variability in Dynamic Response of Non Self-Adjoint Mechanical Systems
Authors: Venkatesan S. , Ganesan R.
Published: March 2021

Variations in strength, geometric and deterioration characteristics of both materials and machine components are quite common in real-life mechanical systems due to manufacturing defects and measurement errors. Such inherent fluctuations which are unavoidable even with the best quality control measures, are essentially random in nature. Effects of these random fluctuations on the performance levels, dynamic response and service life of mechanical systems need to be evaluated based on a stochastic approach, in order to assist design and diagnostics of industrial machinery. Non self-adjoint eigenproblems that correspond to the dynamic response of complex mechanical systems such as high speed rotors, fluid-flowing pipes and actively controlled structures are considered in the present work. The coefficients of the matrices are stochastic processes and are resulting from uncertain parameters of the mechanical system being described by the eigenproblem. A perturbational solution is sought and obtained in a form that does not involve repeated solutions of a recursive set of equations. Sample functions are generated based on the perturbational expansion and response moments are obtained by treating uncertain fluctuations to be stochastic perturbations. Complete covariance structures of both eigenvalues and eigenvectors are obtained through computationally efficient expressions. Applications of the developed procedure for real-life mechanical systems, that have uncertain material properties, are demonstrated.
Chaotic Vibration in Aircraft Braking Systems
Authors: Özbek M. Akif , Liu Steve Y. , Gordon James T. , Newman David S. , Atilgan Ali R.
Published: March 2021

Typical vibration modes of aircraft braking systems are discussed in this paper. Special attention is given to squeal vibrations of carbon brakes. From flight tests, a wide range of response amplitudes are analyzed to determine the nature of the motion. Fourier analysis indicates the presence of a high amplitude limit cycle which seems to be initiated by a transient chaotic region. A singular system approach based on a time delay embedding confirms this finding. Time delay analysis makes it possible to contruct model equations via which intrinsic dynamics of the system can be recovered, and opens up the possibility of preventing large amplitude vibration by controlling the chaotic motion.