bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural origin of thermally induced refractive index changes in Yb3+/Al3+/P5+/F−‐co‐doped silica glass
Authors: Guo Mengting , Wang Shikai , Zhao Tongyao , Shao Chongyun , Feng Suya , Yu Chunlei , Ren Jinjun , Hu Lili
Published: March 2021

In this work, the relationship among the thermal history, refractive index (RI), and structures of Yb3+/Al3+/P5+/F−‐co‐doped silica glass is studied. We reveal the structural origin of the thermally induced RI change in the Heraeus F300 and Yb3+/Al3+/P5+/F−‐co‐doped silica glasses with different states of thermal history by advanced solid‐state nuclear magnetic resonance and Raman scattering techniques, and the effect of the thermal history on the beam quality of Yb3+‐doped large‐mode‐area photonic crystal fiber (LMA PCF). The structural analysis demonstrates that the RI change in the glass is inextricably linked to the change in the AlPO4 domains, coordination number of the Al and Si–O–Si rings. An intimate and direct connection of the thermally induced physical behaviors is developed with the structural pictures of glasses, and the beam quality of the LMA PCF is greatly improved by proper thermal annealing. The results provide a significant reference for the precise manipulation of the numerical aperture of Yb3+‐doped active fiber.
Up‐regulation of circRNA_0068481 promotes right ventricular hypertrophy in PAH patients via regulating miR‐646/miR‐570/miR‐885
Authors: Guo Hong‐mei , Liu Zi‐peng
Published: March 2021

CircRNA‐0068481 and several miRNAs are important in the pathogenesis of right ventricular hypertrophy (VH), while the inhibition of eye absent transcriptional coactivator and phosphatase 3 (EYA3) was proved to reverse vascular remodelling in rats. In this study, we tried to study the diagnostic value and mechanistic role of circRNA_0068481 in the diagnosis of RVH in PAH patients. qPCR was done to measure circRNA‐0068481, miR‐646, miR‐750, miR‐885 and EYA3 mRNA expression. Luciferase assay was done to explore the regulatory relationship between circRNA‐0068481/EYA3 and the miRNAs. Western blot was done to measure EYA3 expression in AC16 cells. The expression of circRNA‐0068481, miR‐646 and miR‐570 showed a considerable capability to diagnose RVH in PAH patients. The luciferase activity of circRNA‐0068481 was remarkably suppressed by miR‐646, miR‐570 or miR‐885. The luciferase signal of EYA3 was also inhibited by miR‐646, miR‐570 and miR‐885. Up‐regulation of circRNA‐0068481 expression in AC16 significantly decreased miR‐646, miR‐570 and miR‐885 expression, and up‐regulated EYA3 expression, whereas circRNA‐0068481 down‐regulation significantly increased miR‐646, miR‐570 and miR‐885 expression, and repressed EYA3 expression. CircRNA_0068481 sponged several miRNAs including miR‐646, miR‐570 and miR‐885. These miRNAs were all found to target the expression of EYA3 mRNA, which is involved in the onset of right ventricular hypertrophy. Therefore, it can be concluded that the up‐regulation of circRNA_0068481 can predict the diagnosis of right ventricular hypertrophy in pulmonary arterial hypertension patients.
Diet quality and periodontal disease: Results from the oral infections, glucose intolerance and insulin resistance study (ORIGINS)
Authors: DeMayo Francesco , Molinsky Rebecca , Tahir Muna J. , Roy Sumith , Genkinger Jeanine M. , Papapanou Panos N. , Jacobs David R. , Demmer Ryan T.
Published: March 2021

Aims

This study examined the cross‐sectional association between diet quality and periodontal disease.

Materials and methods

In the Oral Infections, Glucose Intolerance and Insulin Resistance Study (ORIGINS), 923 individuals completed the National Cancer Institute's validated Diet History Questionnaire 1, from which the Alternative Healthy Eating Index (AHEI) scores and A Priori Diet Quality Scores (APDQS) were calculated. Mean probing depth (MPD), mean clinical attachment loss (MAL) and % of sites bleeding on probing (%BOP) were derived from full‐mouth periodontal exams. Multivariable adjusted linear and logistic regression models assessed the associations between diet quality and MPD, MAL, %BOP, and the odds of periodontitis (defined via the CDC/AAP classification).

Results

Alternative Healthy Eating Index and APDQS were not associated with MPD, MAL, or periodontitis. While AHEI was also not associated with %BOP, the APDQS was associated with %BOP (p = .03). Higher nut consumption was related to lower MPD (p = .03) and periodontitis odds (p = .03). Higher red meat consumption was associated with higher MPD (p = .01) and %BOP (p = .05). Higher trans‐fatty acid consumption was also associated with increased %BOP (p = .05).

Conclusion

Overall diet quality scores were not associated with periodontal status. Future studies are necessary to replicate the associations observed in this study to minimize the risk of false discovery.
Home Birth in Rural Zambia: The Role of Intimate Partner Violence and Autonomous Decision‐Making
Authors: Beck Dana , Veliz Philip T. , Munro‐Kramer Michelle , Ngoma Thandiwe , Scott Nancy , Kaiser Jeanette L. , Musonda Gertrude , Lori Jody R.
Published: March 2021

Introduction

Skilled care is indicated as a measure to prevent the deaths of pregnant women across sub‐Saharan Africa. Despite this, many women continue to give birth at home. There has been little attention as to how the experience of intimate partner violence (IPV) or autonomous decision‐making about place of birth influences home births in rural Zambia. This study explores how markers of sociocultural gender inequities (prevalence of IPV and autonomous decision‐making) correlate with home birth in rural Zambia.

Methods

This secondary analysis uses quantitative data from a baseline household survey with women who had given birth within the past 13 months in rural Zambia. Control variables shown to be significant in the literature were included in the model, and binary logistic regression was used to assess the influence of IPV and autonomous decision‐making on home birth.

Results

This sample included 2381 women from rural Zambia, of whom 384 reported a home birth within the past 13 months. Women who were autonomously making the decision about where to give birth were more likely to have a home birth (adjusted odds ratio [AOR], 1.729; SE, 0.210; 95% CI, 1.362‐2.194; P < .001). Self‐report of experiencing physical IPV in the past 2 weeks was not significant in predicting home birth (AOR, 0.783; SE, 0.181; 95% CI, 0.496‐1.234; P = .293). Women who self‐identified as Tumbuka or other, were able to afford school fees, had completed secondary education or higher, were married, and had 4 or more antenatal care visits were significantly less likely to report a home birth.

Discussion

This quantitative analysis did not corroborate findings from other research that implicates IPV as a predictor of home birth. Additionally, autonomous decision‐making was not associated with a decrease in home births. Future work should incorporate qualitative or mixed methods strategies to comprehensively explore household‐ and facility‐level interventions to promote facility birth.
Cryptic diversity and significant cophylogenetic signal detected by DNA barcoding the rust fungi (Pucciniaceae) of Cyperaceae–Juncaceae
Authors: Léveillé‐Bourret Étienne , Eggertson Quinn , Hambleton Sarah , Starr Julian R.
Published: March 2021

Plants play important roles as habitat and food for a tremendous diversity of specialist animals and fungi. The disappearance of any plant species can lead to extinction cascades of its associated biota. In consequence, documenting the diversity and specificity of plant‐associated organisms is of high practical relevance in biodiversity conservation. Here, we present the first large‐scale molecular investigation into the diversity, host specificity, and cophylogenetic congruence of an especially rich plant–fungal association, the rust fungi (Pucciniaceae) of Cyperaceae and Juncaceae. Using the largest rust fungi DNA barcoding dataset published to date (252 sequences, 82 taxa), we reject the presence of a global ITS2‐28S barcode gap, but find a local gap in Cyperaceae–Juncaceae rusts, and suggest the existence of many cryptic species in North America, with some broadly circumscribed species possibly corresponding to >10 cryptic species. We test previous hypotheses of correlations between the phylogenies of rust fungi and their Cyperaceae–Juncaceae hosts using a combination of global‐fit and event‐based cophylogenetic methods. A significant cophylogenetic signal is detected between rusts and their hosts, but the small number of cospeciations argues for preferential host jumps as the driving process behind these correlations. In addition, temporal congruence between the origin of major Carex clades and their rusts suggests that host diversification may have promoted parasite diversification. Finally, we discuss the relevance of rust infection patterns to the systematics of Cyperaceae, highlight some taxonomic problems uncovered by the analyses, and call attention to the promise of DNA barcoding for bridging knowledge gaps in poorly studied plant‐associated microorganisms.
Short‐term results of stress urinary incontinence in women undergoing laparoscopic sacrocolpopexy with and without midurethral sling
Authors: Huang Kuan‐Hui , Chang Yu‐Wei , Ngo Yeh Giin , Wu Ling‐Ying , Yang Tsai‐Hwa , Lee Yi‐Ling , Chuang Fei‐Chi
Published: March 2021

Objectives

This study aimed to assess the short‐term results of stress urinary incontinence (SUI) in women undergoing laparoscopic sacrocolpopexy (LSC) with and without midurethral sling (MUS).

Methods

This retrospective study was conducted from July 2012 to December 2017. Women with stage 3 or 4 in the Pelvic Organ Prolapse Quantification (POP‐Q) who underwent LSC were recruited. Multichannel urodynamic studies were performed in all women. Assessment included pre‐ and postoperative POP‐Q stages, urodynamic parameters, peri‐ and postoperative complications, and symptoms.

Results

One hundred and eighteen patients met the inclusion criteria in total. A total of 19.5% (23/118) of them had concomitant MUS. The mean follow‐up duration was 16.9 ±  16.0 (range 3–69) months. Meanwhile, 33.9% (40/118) of the patients were diagnosed with overt SUI, and 50% (20/40) underwent MUS. In the concomitant MUS group, the rate of having postoperative SUI was only 5% (1/20). Patients diagnosed with SUI and without concomitant MUS had a 45% rate (9/20), and 25% of them (5/20) received MUS later. Preoperatively, 16.1% (19/118) of the patients were diagnosed with occult SUI. Among the patients without anti‐incontinence sling during prolapse surgery, 25% (4/16) of them complained about having SUI during the follow‐up. However, none of the women required subsequent anti‐incontinence surgery. Postoperative de novo SUI occurred to 13.6% (16/118) of them. None of the patients received further operation. Based on the preoperative and postoperative urodynamic studies in the combination surgery group, a significant improvement was observed in the pad test.

Conclusions

The combination of LSC with MUS procedure is likely to be beneficial in selected patients.
Coordinated control of the type IV pili and c‐di‐GMP‐dependent antifungal antibiotic production in Lysobacter by the response regulator PilR
Authors: Xu Kangwen , Shen Danyu , Yang Nianda , Chou Shan‐Ho , Gomelsky Mark , Qian Guoliang
Published: March 2021

In the soil gammaproteobacterium Lysobacter enzymogenes, a natural fungal predator, the response regulator PilR controls type IV pili (T4P)‐mediated twitching motility as well as synthesis of the heat‐stable antifungal factor (HSAF). Earlier we showed that PilR acts via the second messenger, c‐di‐GMP; however, the mechanism remained unknown. Here, we describe how PilR, c‐di‐GMP signalling, and HSAF synthesis are connected. We screened genes for putative diguanylate cyclases (c‐di‐GMP synthases) and found that PilR binds to the promoter region of lchD and down‐regulates its transcription. The DNA‐binding affinity of PilR, and therefore its repressor function, are enhanced by phosphorylation by its cognate histidine kinase, PilS. The lchD gene product is a diguanylate cyclase, and the decrease in LchD levels shifts the ratio of c‐di‐GMP‐bound and c‐di‐GMP‐free transcription factor Clp, a key activator of the HSAF biosynthesis operon expression. Furthermore, Clp directly interacts with LchD and enhances its diguanylate cyclase activity. Therefore, the PilS–PilR two‐component system activates T4P‐motility while simultaneously decreasing c‐di‐GMP levels and promoting HSAF production via the highly specific LchD–c‐di‐GMP–Clp pathway. Coordinated increase in motility and secretion of the “long‐distance” antifungal weapon HSAF is expected to ensure safer grazing of L. enzymogenes on soil or plant surfaces, unimpeded by fungal competitors, or to facilitate bacterial preying on killed fungal cells. This study uncovered the mechanism of coregulated pili‐based motility and production of an antifungal antibiotic in L. enzymogenes, showcased the expanded range of functions of the PilS–PilR system, and highlighted exquisite specificity in c‐di‐GMP‐mediated circuits.
Embodying Britishness: National identity in the United Kingdom
Authors: Tranter Bruce , Donoghue Jed
Published: March 2021

Some argue that national identity is constructed from the shared myths and ‘collective memories’ of a nation, where heroes from a ‘golden age’ and legendary figures embody national identity. However, when a national sample of British adults were asked to name the most important Britons, living or dead, they did not hark back to legendary figures, military leaders or sporting heroes, but identified their monarch, political leaders, and to a lesser extent, ‘household heroes’ within their own family. ‘Banal’, quotidian political leaders and Queen Elizabeth II symbolise national identity in Britain, although they sit alongside ‘hot’ signifiers of nationalism personified, such as football hero David Beckham. This research suggests that studies of national identity should not be limited to examining essentialist claims of ethnonationalism, or civic attachments to laws and institutions, but also explore those whom the citizens of a given country identify as embodying their national identity.
In Living Memory: The Demographic Dynamics of Event Recollection in a Stable Population*
Authors: Denton Frank T. , Spencer Byron G.
Published: March 2021

We model a stable population that has experienced an important historical event and the declining proportion, as time passes, of the population that remembers that event. The proportion is determined by the demographic characteristics of the population, including its age distribution, the natural rate of growth, the underlying birth rate, the life table probabilities to which the population is subject, and the effects of immigration and emigration under alternative assumptions about the nature of the event. (We distinguish between “local” and “universal” events.) It is determined also by the choice of an age of awareness of children at the time the event occurred. We preface development of the model by noting examples of major events of the kind we have in mind and, after development, explore the model's sensitivity to different parameter specifications by experimental simulation. The output of each experiment is a sequence of “remembering” proportions at successive decade intervals and the corresponding mean ages of the “rememberers” in relation to the overall mean age of the population.
Insertion of cuff inflation line into pediatric tracheal tubes related to oral and nasal tracheal intubation depth
Authors: Kemper Michael , Fischer Martina , Grass Beate , Dave Mital H. , Weiss Markus
Published: March 2021

Background

In clinical practice, the cuff inflation line of cuffed pediatric tracheal tubes often interferes with securing tracheal tubes.

Methods

The insertion site of the cuff inflation lines and the lengths of four different brands and nine sizes of commonly used cuffed pediatric tracheal tubes were measured and compared in vitro with oral and nasotracheal intubation depths as calculated by different formulas for pediatric patients aged from birth to 16 years. Motoyama's recommendation was used for age‐related size selection of cuffed pediatric tracheal tubes.

Results

The proportion of the distance from the tracheal tube tip to the insertion site of the cuff inflation line varied considerably between the tracheal tubes (Microcuff: 48.5–60.7%; Parker: 48.7–73.2%; Ruesch: 59.1–77.8%; and Shiley: 46.0–60.3%). Using different formulas for oral or nasotracheal intubation depth, the insertion site of the cuff inflation line was placed within the oral or nasal cavity or within an area 1 cm beyond the teeth or the nostrils in almost all tracheal tubes tested. Positioning the insertion site 2 cm from the proximal end of the tracheal tubes resulted in a cuff line–free tube area of ≥1 cm in all orally and almost in all nasally inserted tracheal tubes, considering maximum recommended tracheal intubation depths.

Conclusion

The cuff inflation line in almost all commonly used cuffed pediatric tracheal tubes interferes with securing the tracheal tube due to its insertion site into the tracheal tube. This potentially carries the risk of kinking, obstruction, or damage to the cuff inflation line with ensuing failure to deflate or inflate the cuff. The proposed position of the insertion of the cuff inflation line 2 cm from the proximal end of the tracheal tube would ensure a 1‐cm‐wide cuff line–free circular area beyond the oral or nasal cavity in nearly all assessed tracheal tube sizes.
Prospective evaluation of plasma lactate parameters for prognosticating dogs with shock
Authors: Blutinger Alex Louis , Zollo Ann Marie , Weltman Joel , Prittie Jennifer
Published: March 2021

Objective

To determine whether admission venous plasma lactate concentration, serially calculated lactate variables, or the Acute Patient Physiologic and Laboratory Evaluation (APPLEfast) score could discriminate hospital survivors from non‐survivors in dogs presenting to the emergency department with clinical signs of shock.

Design

Prospective case series performed over a 24‐month period.

Setting

Large urban private teaching hospital.

Animals

Seventy‐one dogs admitted to the ICU with initial peripheral venous plasma lactate concentration > 2.5 mmol/L and clinical and hemodynamic parameters consistent with shock.

Interventions

None.

Measurements and main results

Heart rate, systolic blood pressure, temperature, initial venous plasma lactate, and APPLEfastscore were recorded at admission. Lactate concentrations were serially recorded at predefined time points and used to calculate lactate variables, including lactime (time lactate > 2.5 mmol/L), lactate clearance ([lactateinitial– lactatedelayed]/ lactateinitial× 100), and LACAREA(area under the lactate concentration versus time curve). Primary outcome was survival to discharge. Overall survival rate was 61%. Admission plasma lactate did not differ between groups (P = 0.28). Lactime was shorter in survivors vs non‐survivors (P = 0.03). Lactate clearance at hours (h) 1, 4, 10, and 16 was greater in survivors vs non‐survivors (P < 0.05). Final plasma lactate clearance differed between groups (P < 0.05). LACAREAat time intervals 1 to 4 hours, 4 to 10 hours, 10 to 16 hours, and 16 to 24 hours was larger in non‐survivors vs survivors (P < 0.05). Total LACAREAdid not differ between groups (P = 0.51). Admission APPLEfastwas not different between survivors and non‐survivors (P = 0.16).

Conclusions

While neither single APPLEfastnor admission plasma lactate concentration could discriminate between hospital survivors and non‐survivors, measures of lactate clearance can prognosticate survival in dogs with shock.
Hemostatic capacity of canine chilled whole blood over time
Authors: Edwards Thomas H. , Darlington Daniel N. , Pusateri Anthony E. , Keesee Jeffrey D. , Ruiz Daikor D. , Little Joshua S. , Parker Jacquelyn S. , Cap Andrew P.
Published: March 2021

Objective

To determine the hemostatic potential of canine chilled whole blood maintained at clinically relevant storage conditions.

Design

In vitro experimental study.

Setting

Government blood and coagulation research laboratory and government referral veterinary hospital.

Animals

Ten healthy Department of Defense military working dogs.

Interventions

One unit of fresh whole blood was collected from each of 10 military working dogs using aseptic technique. Blood was maintained in a medical‐grade refrigerator for 28 days at 4°C (39°F) and analyzed before refrigeration (day 0) and after (days 2, 4, 7, 9, 11, 14, 21, and 28).

Measurements and main results

Ten units of canine blood were analyzed with whole blood platelet aggregation, thromboelastography, CBC, biochemical analysis, blood gas, and prothrombin/activated partial thromboplastin/fibrinogen assay. Clotting strength of chilled blood was maintained up to 21 days despite significant decreases in platelet aggregation to ADP, collagen, or γ‐thrombin, significant prolongation of prothrombin and activated partial thromboplastin times, and reduced speed of clot formation (K time, alpha angle). Fibrinogen concentration, WBC, RBC, and platelet counts did not change over time.

Conclusions

Chilled canine whole blood loses a small percentage of clot strength through 21 days of refrigerated storage. Further research is needed to determine if this hemostatic potential is clinically relevant in hemorrhaging dogs who require surgical intervention or are exposed to traumatic events.
Association of ABO blood group with postoperative total bleeding volume in patients undergoing total hip arthroplasty
Authors: Maezawa Katsuhiko , Nozawa Masahiko , Gomi Motoshi , Sugimoto Munehiko , Maruyama Yuichiro
Published: March 2021

Background and objectives

As individuals with blood types A, B and AB have approximately 25% higher levels of vWF than those with type O, the risk of developing venous thrombotic events has been investigated in a number of clinical studies, but whether individuals with type O blood experience increased bleeding remains to be clarified. The purpose of this study was to evaluate an association of ABO blood group with intraoperative bleeding and postoperative total bleeding in patients undergoing total hip arthroplasty.

Materials and methods

We prospectively recruited 84 women who were undergoing total hip arthroplasty. The differences between blood groups in mean age, body weight, preoperative and postoperative Hct levels, and postoperative/preoperative Hct ratio, intraoperative bleeding volume (IBV), and total bleeding volume (TBV) were evaluated.

Results

Twenty‐six patients had type A blood, 17 had type B, 9 had type AB, and 30 had type O. There were no significant differences in mean age, body weight or operating time between the different ABO blood groups. While there was no significant difference in these Hct levels or IBV among the different blood groups, there was a significant difference in TBV between type O and type AB, and between type O and non‐type O.

Conclusion

Our study in patients undergoing total hip arthroplasty suggests that patients in blood group O tend to have large amounts of bleeding.
The Impact of Oil Shocks on Exchange Rates: The Case of Selected OPEC Countries
Authors: Fattahi Shahram , Moridi Zainab , Moridi Rasoul
Published: March 2021

OPEC countries are heavily dependent on oil dollar revenues through which impact on exchange rates. The purpose of this study is to investigate the effect of oil shocks on the real exchange rates for selected OPEC countries for the period 1980-2018. The oil shocks are first obtained using the vector auto-regression model and then their effects on the exchange rates are estimated using a panel quantile regression model. The results show that effect of oil shocks on exchange rates varies across quantiles. The oil specific-demand shock and global demand shock have a negative and significant effect on the real exchange rates while the oil supply shock has a positive and significant effect on the real exchange rates in OPEC countries. Furthermore, oil specific-demand shock has the most impact on the real exchange rates.
The envelope protein of SARS‐CoV‐2 increases intra‐Golgi pH and forms a cation channel that is regulated by pH
Authors: Cabrera‐Garcia David , Bekdash Ramsey , Abbott Geoffrey W. , Yazawa Masayuki , Harrison Neil L.
Published: March 2021

Key points

We report a novel method for the transient expression of SARS‐CoV‐2 envelope (E) protein in intracellular organelles and the plasma membrane of mammalian cells and Xenopus oocytes.

Intracellular expression of SARS‐CoV‐2 E protein increases intra‐Golgi pH.

By targeting the SARS‐CoV‐2 E protein to the plasma membrane, we show that it forms a cation channel, viroporin, that is modulated by changes of pH.

This method for studying the activity of viroporins may facilitate screening for new antiviral drugs to identify novel treatments for COVID‐19.

The envelope (E) protein of coronaviruses such as SARS‐CoV‐1 is proposed to form an ion channel or viroporin that participates in viral propagation and pathogenesis. Here we developed a technique to study the E protein of SARS‐CoV‐2 in mammalian cells by directed targeting using a carboxyl‐terminal fluorescent protein tag, mKate2. The wild‐type SARS‐CoV‐2 E protein can be trafficked to intracellular organelles, notably the endoplasmic reticulum–Golgi intermediate complex, where its expression increases pH inside the organelle. We also succeeded in targeting SARS‐CoV‐2 E to the plasma membrane, which enabled biophysical analysis using whole‐cell patch clamp recording in a mammalian cell line, HEK 293 cells, and two‐electrode voltage clamp electrophysiology in Xenopus oocytes. The results suggest that the E protein forms an ion channel that is permeable to monovalent cations such as Na+, Cs+ and K+. The E current is nearly time‐ and voltage‐independent when E protein is expressed in mammalian cells, and is modulated by changes of pH. At pH 6.0 and 7.4, the E protein current is activated, whereas at pH 8.0 and 9.0, the amplitude of E protein current is reduced, and in oocytes the inward E current fades at pH 9 in a time‐ and voltage‐dependent manner. Using this directed targeting method and electrophysiological recordings, potential inhibitors of the E protein can be screened and subsequently investigated for antiviral activity against SARS‐CoV‐2 in vitro and possible efficacy in treating COVID‐19.
Mechanical Activation—A Newly Developed Chemical Process
Authors: Shaw M. C.
Published: March 2021

In the course of a fundamental study of metal cutting it was found that a cutting fluid encounters a rather unusual combination of conditions at the point of a cutting tool. The fluid is subjected to high local pressures of the order of the hardness of the metal cut, high local temperatures limited only by the melting point of the work material, and nascent highly stressed metal surfaces. This combination of conditions will, in general, promote a chemical reaction. The organic chemist uses reactions between metals and organic reagents in chemical synthesis, many of these so-called organometallic reactions being difficult to initiate and control. In this paper it is shown how the metal-cutting process may be employed in the preparation of organometallic compounds. The metal involved in the preparation is cut in the presence of the other reactants, thus utilizing the high-temperature, high-pressure, and highly stressed nascent surface produced at the point of cutting to start the reaction. This process has been called mechanical activation. This new chemical technique promises to give many extremely versatile organometallic reactions a commercial significance which they have heretofore lacked because their application was limited to batch rather than continuous processes by the inflammability and toxicity of the reactants, and the difficulty of starting and controlling the reaction.
Reinforcement of a Small Circular Hole in a Plane Sheet Under Tension
Authors: Levy Samuel , McPherson A. E. , Smith F. C.
Published: March 2021

This paper presents a theoretical and experimental investigation of the effect of various reinforcements on the stresses and displacements near a small circular hole in a plane sheet under load in its plane. The first part of the paper gives a plane-stress analysis for a reinforcement of variable thickness when the load is a uniform tension in all directions. It is found that a reinforcement which crowds most of the material close to the edge of the hole is most effective in reducing the stress concentration at the hole. The next part presents the principal results of earlier plane-stress analyses for reinforcement by a “doubler plate” when the load is tension in one direction only. The last part describes tests in the elastic range of riveted doubler-plate reinforcements of several sizes and with several rivet arrangements. Details of a test to failure of one reinforcement riveted to one side of the sheet only are given. The tests indicate that the plane-stress theory gives a good estimate of the state of stress outside the reinforcement, and that it may be used for computing median-surface stresses and average elongations of the hole in the specimen, provided that the reinforcement is attached to the sheet by more than one row of rivets.
Vibration of a Cantilever Beam With Prescribed End Motion
Authors: Nothmann G. A.
Published: March 2021

A cantilever beam, vibrating as a result of prescribed motion of its end, is studied with particular regard to the force required to maintain such motion. The end motions in the four basic problems solved are, respectively, uniform acceleration; uniform acceleration, uniform velocity; uniform acceleration, uniform velocity, uniform deceleration, rest; and sinusoidal pulse, rest. Figs. 5, 6, 7, and 8, respectively, of the paper show the end-force variation for each of the problems considered. The method of analysis indicates that the end force on the beam may be obtained in each instance by super-position of certain basic components. The results show how the parameters of the prescribed motion determine the magnitude of the fluctuations and the direction of the corresponding end force.
Assessment of Turbulent Combustion Models for Simulating Prechamber Ignition in a Natural Gas Engine
Authors: Kim Joohan , Scarcelli Riccardo , Som Sibendu , Shah Ashish , Biruduganti Munidhar S. , Longman Douglas E.
Published: March 2021

Lean combustion is a promising strategy to increase thermal efficiency in an internal combustion engine, by exploiting a favorable specific heat ratio of the fresh mixture while simultaneously suppressing the heat losses to the cylinder wall. However, unstable ignition and slow flame propagation at fuel-lean conditions lead to large cycle-to-cycle variability and limit the high-efficiency engine operating range. Prechamber ignition is considered an effective concept to extend the lean operating limit, by providing spatially distributed ignition with multiple turbulent flame-jets and enabling a faster combustion rate compared to the conventional spark ignition approach. From a numerical modeling standpoint to date science base and available simulation tools are inadequate to properly understand and predict the combustion processes in prechamber ignited engines. In this paper, conceptually different Reynolds-averaged Navier–Stokes (RANS) combustion models widely adopted in the engine modeling community are used to simulate the ignition and combustion processes in a medium-duty natural gas engine with a prechamber spark-ignition system. A flamelet-based turbulent combustion model, i.e., G-equation, and a multizone well-stirred reactor model are employed for this modeling study. Simulation results are compared with experimental data in terms of in-cylinder pressure and heat release rate. Finally, the analysis of the performance of the two models is carried out to highlight the strengths and limitations of the two evaluated approaches.
Effects of Carbonization on the Co-Activation of Sludge and Biomass to Produce Activated Coke
Authors: Wang Liwei , Lu Lin , Li Minghua , Liu Yulin , Ren Xiaohan , Levendis Yiannis A.
Published: March 2021

Activated coke was prepared by mixing sewage sludge and waste poplar bark biomass from furniture manufacturing. The physical activation method of these feedstocks with steam for 1 h at 850 °C was implemented. The elemental composition, pore distribution, microstructure, and surface functional groups of the activated coke products were analyzed by proximate analysis, ultimate analysis, N2 adsorption, scanning electron microscopy, and Fourier transform infrared spectroscopy, respectively. The effects of different mixing ratios of sludge and biomass, preactivation carbonization temperature, and activation method on the activated coke were investigated. When the proportion of biomass was two-thirds of the total feedstock mass and the carbonization temperature was 300 °C, the produced activated coke had the highest specific surface area and the most extended micropore structure. Water vapor (steam) activation was found to be beneficial to the formation of oxygen-containing functional groups. This study established that steam is beneficial to pore expansion and promotes pore development. It was found that the carbonaceous feedstocks acquired initial porosity through carbonization in nitrogen, which proved to be instrumental in the ensuing activation process. After sequential carbonization and activation, the produced active coke acquired a higher specific surface area and microporosity, compared with the active coke produced by activation alone.
Stabilization Device for a Rigid Disc Excited by Friction
Authors: Miyasato Hugo Heidy , Segala Simionatto Vinícius Gabriel , Dias Milton
Published: March 2021

Models for rotating rigid discs excited by contact elements have been developed for the study of break noise and vibration. More recently, models for clutch squeal/eek noise have been developed as well. Such phenomenological representations, even though simple, are of great help for designers given that many physical features can be included, such as the circulatory and gyroscopic effects. Instability or self-excited vibrations are represented by wobbling motions. In this study, a device is included as a disc connected to the primary system by a set of spring and damping elements. A complex coordinate notation was helpful to make a concise physical description of the in-phase and out-of-phase wobbling motions between the bodies. If its properties are properly adjusted, all modes interact (indicating veering or crossings between the eigenvalue loci), and the system is stabilized.
Investigation on the Rotational Dynamics of a Timing Belt Drive Including an Oval Driving Pulley
Authors: Passos Sébastien , Manin Lionel , Remond Didier , Sauvage Olivier , Rota Laurent , Besnier Etienne
Published: March 2021

Recent developments in timing belt drive for the automotive engine have seen the use of non-circular pulleys. This study presents an experimental and numerical investigation on this type of transmission including an oval pulley. A specific test rig has been designed to enable the identification of the proper effect of an oval pulley on the transmission dynamics. The belt tensions, the speeds, and torques of the driving and driven pulleys were measured and analyzed for three different transmission configurations: (1) circular driving pulley and oval driving pulley without (2) and/or with (3) load torque applied. Analyses were carried out in the time and frequency domains by considering the driving pulley rotation angle as a reference. In parallel a numerical model has been developed, it accounts for the specific motions of the belt seating/unseating points on the oval pulley and its neighboring pulleys. The model considers the variation of lengths for the belt spans adjacent to the oval pulley. This induces variable longitudinal stiffness and influences the transmission dynamics that is predicted versus time and compared with experiments. The phasing angle of the oval driving pulley was adjustable in order to study its influence. With no resistant torque applied, it was found that, for low-speeds, the oval pulley has a pure kinematic effect on the transmission dynamics. When a load torque is applied, the effectiveness of the oval pulley regarding the belt tensions and transmission error fluctuations is verified experimentally for some specific intervals of the phasing angle.
SINFONIA: An Open Feature-Based Design Module
Authors: Ovtcharova J. , Haßinger S. , Vieira A. S. , Jasnoch U. , Rix J.
Published: March 2021

Sinfonia is a module for feature-based design which is configurable to users and applications within diverse CAD environments, particularly in the area of mechanical engineering. Sinfonia has an open and modular architecture that allows to modify and extend existing functionalities, and to integrate new modeling facilities and application tasks. This module enables the users to work with standard pre-defined design features delivered with the module, or to define dynamically their own specific design features during the design session. Furthermore, Sinfonia allows the interactive definition of constraints concerning the product semantics. Definition and administration of constraints in feature-based models provided by a consistency manager is supported to reach semantical correctness of the part models.

The main modules of Sinfonia are the Feature Modeler and the Design Feature Manager. The Feature Modeler is responsible for the instantiation of features and the creation of the feature-based model. The Design Feature Manager allows feature data and design processes to be managed in a uniform way. The CAD system environment in which Sinfonia is integrated consists of the following modules: the User Interface System and the Application modules (offering tools for interaction of the user with application specific part models and for communication with external systems and applications, such as NC modules, etc.), the Solid Modeler (responsible for creating the shape representation of the feature-based model), the Consistency Manager (providing services to handle all kinds of different constraints within the design environment) and the Product Database which includes all services for storing and retrieving various product data.
Compatibility Analysis of Product Design for Recyclability and Reuse
Authors: Di Marco Patrick , Eubanks Charles F. , Ishii Kos
Published: March 2021

This paper describes a method for evaluating the compatibility of a product design with respect to end-of-life product retirement issues, particularly recyclability. Designers can affect the ease of recycling in two major areas: 1) ease of disassembly, and 2) material selection for compatibility with recycling methods. The proposed method, called “clumping,” involves specification of the level of disassembly and the compatibility analysis of each remaining clump with the design’s post-life intent; i.e., reuse, remanufacturing, recycling, or disposal. The method uses qualitative knowledge to assign a normalized measure of compatibility to each clump. An empirical cost function maps the measure to an estimated cost to reprocess the product. The method is an integral part of our life-cycle design computer tool that effectively guides engineers to an environmentally responsible product design. A refrigerator in-door ice dispenser serves as an illustrative example.
Using Features to Support Finite Element Idealizations
Authors: Dabke Padmanabh , Prabhakar Vallury , Sheppard Sheri
Published: March 2021

This paper describes how feature-based techniques can be used in a knowledge-based system to support finite element idealizations. Any system of this kind must have two important features. First, it must capture the experiential and heuristic knowledge used by expert analysts in making idealization decisions. Second, the system must be able to perform spatial reasoning about the finite element model being analyzed.

The first requirement led us to incorporate knowledge-based reasoning in the idealization systems. We chose the formalism of “features” to capture the spatial reasoning because expert analysts often describe the idealization process in terms of removing / modifying features (such as holes, slots, notches, etc.) and their spatial properties.
Feature Based Description of Modular Fixturing Elements: The Key to an Expert System for the Automatic Design of the Physical Fixture
Authors: Perremans P.
Published: March 2021

This paper reports on the development of an expert system for the design of the physical fixture for the fixturing of prismatic parts on machining centers. A brief description of the Brite project 3480 IDEFIX in which the system was developed is given. With as input the faces on which positioning, clamping and/or supporting should be done the expert system generates the needed assembly of modular fixturing elements (i.e. the physical fixture). New in the approach is the description of modular elements by means of form features. This method permits the description of an arbitrary modular fixturing system (with the only restriction that it has to be based on a grid of holes) and the use of the same logic to determine the assembly of modular elements.
Development of an Optimization Method for Determination of Process Sequences Considering Prismatic Workpieces
Authors: Taiber Joachim G.
Published: March 2021

In the field of process planning most of the working time is spent for the following activities:

machine tool and tool assignment

determination of the set-up and process sequence

definition of tool paths

optimization of cutting parameters

The quality how these activities are done influence substantially manufacturing cost that are to be minimized.

The more complex a planning task is the more difficult it is for the planner to work out an optimal solution within reasonable time.

In this article it will be discussed how process planning of prismatic workpieces considering drilling and milling machining can be optimized by computer assistance.
Hierarchical Production Planning for Complex Manufacturing Systems
Authors: Mehra Anshu , Minis Ioannis , Proth Jean M.
Published: March 2021

A hierarchical approach to production planning for complex manufacturing systems is presented. A single facility comprising a number of work-centers that produce multiple part types is considered. The planning horizon includes a sequence of time periods, and the demand for all part types is assumed to be known. The production planning problem consists of minimizing the holding costs for all part types as well as the work-in-process, and backlogging cost for the end items. We present a two-level hierarchy that is based on aggregating parts to part families, work-centers to manufacturing cells and time periods to aggregate time periods. The solution at the aggregate level is imposed as a constraint to the detailed level problem which employs a decomposition based on manufacturing cells. This architecture uses a rolling horizon strategy to perform the production management function. We have employed perturbation analysis techniques to adjust certain parameters of the optimization problems at the detailed level to reach a near-optimal detailed production plan.
Application of a Bayesian Network to Integrated Circuit Tester Diagnosis
Authors: Mittelstadt Daniel , Paasch Robert , D'Ambrosio Bruce
Published: March 2021

We describe research efforts to implement a Bayesian belief network based expert system to solve a real-world diagnostic problem — the diagnosis of integrated circuit (IC) testing machines. We describe the development of several models of the IC tester diagnostic problem in belief networks, the implementation of one of these models using Symbolic Probabilistic Inference (SPI), and discuss the difficulties and advantages encountered in the process.

We observe that modelling with interdependencies in belief networks simplified the knowledge engineering task for the IC tester diagnosis problem, by avoiding procedural knowledge and focusing on diagnostic component’s interdependencies. Several general model frameworks evolved through knowledge engineering to capture diagnostic expertise that facilitated expanding and modifying the networks. However, model implementation was restricted to a small portion of the modelling, contact resistance failures, because evaluation of the probability distributions could not be made fast enough to expand to a complete model with real-time diagnosis. Further research is recommended to create new methods, or refine existing methods, to speed evaluation of the models created in this research. With this accomplished, a more complete diagnosis can be achieved.
Analysis of Linear Nonconservative Vibrations
Authors: Ma Fai
Published: March 2021

The coefficients of a linear nonconservative system are arbitrary matrices lacking the usual properties of symmetry and definiteness. Classical modal analysis is extended in this paper so as to apply to linear nonconservative systems. The extension utilizes equivalence transformations and does not require conversion of the equations of motion to first-order forms. Compared with the state-space approach, the extended modal analysis can offer substantial reduction in computational effort and ample physical insight. Many numerical techniques, for example the collocation method, involve discretized equations resembling those of linear nonconservative vibrations. These numerical techniques can be greatly streamlined if the method of equivalence transformations is incorporated.
Banded Doolittle’s Method for the Solutions of Large Systems of Equations
Authors: Bagci Cemil
Published: March 2021

Doolittle’s method is a much simplified form of Cholesky’s method for solving systems of linear simultaneous equations without inverting the coefficient matrix. In Cholesky’s method the coefficient matrix must be symmetric, the two conjugate triangular matrices must be transposes of each other, and the solution process involves square roots of sums. In Doolittle’s method the coefficient matrix need not be symmetric and there is no constrained relationship between the two conjugate matrices. In this article, Doolittle’s method is used to formulate the banded matrix solution of linear sets of equations of form [A]{X} = {B}, where [A] is symmetric. Such systems of equations occur for many engineering problems, especially for structural finite element formulations where [A] corresponds to the stiffness matrix. In the banded form of [A] the non-zero diagonal rays of one-half of [A] is formed in column form such that [A] is replaced with two conjugate matrices in column forms. The system of equations can then be solved for {X} without inverting [A]. In this paper generalized expressions for the elements of the conjugate matrices, an intermediate unknown parameter matrix, and the {X} matrix are provided for use in programming the method. A curved beam stress analysis is presented to illustrate that the computation time required by the banded Doolittle method is many times less than that of methods such as the regular Doolittle method, the matrix inversion method (using Gauss-Jordan row transformations), Gauss elimination methods, and the banded Cholesky method. Hence, an efficient and less costly process for solving large size engineering systems is offered. A tested FORTRAN program using the banded Doolittle’s method in a subroutine is given in the Appendix.
Numerical Solution to the Radial Sink Flow Between Two Disks
Authors: Vatistas Georgios H. , Ghila Abdurazag , Zitouni Gley
Published: March 2021

A numerical solution to the sink flow between two disks is presented. The numerically predicted pressure is shown to correlate well with the experiment. By comparison to the previous results of the linearized theory, the axial distribution of the radial velocity has been found to be lower at the mid-plane and larger near the disk wall.