bluuebunny/crossref_metadata_2025 huggingface dataset:
Serum Enzyme, Bilirubin, Uric Acid, and Cholesterol Concentration Changes during 7 Days of Total Parenteral Nutrition
Authors: Georgieff M. , Georgieff E.M. , Osswald P. , Lutz H.
Published: July 2017

Lactic dehydrogenase, glutamic oxalacetic transaminase, and alkaline phosphatase remained within normal limits during 7 days of total parenteral nutrition. Five patients showed a rise of total bilirubin up to 1.1 mg/100 ml on the fifth postoperative day, with no change in serum enzymes. Uric acid concentration fell continuously up to the third postoperative day (but within normal limits) and remained decreased until the end of infusion. During the preoperative nutrition period and after surgical intervention, cholesterol concentration showed a steep fall. Very low cholesterol concentrations can cause an alteration of erythrocyte membrane synthesis and should, therefore, be avoided.
Obstructive Sleep Apnea and the Hyoid: A Revised Surgical Procedure
Authors: Riley Robert W. , Powell Nelson B. , Guilleminault Christian
Published: July 2017

Obstructive sleep apnea syndrome results from a loss of muscular activity of pharyngeal dilators and airway collapse at the hypopharynx–base of tongue or the oropharynx–soft palate. The hyoid arch and its muscle attachments strongly affect hypopharyngeal airway patency and resistance. On the basis of these concepts and previous experience, a modified hyoid suspension procedure is presented. Fifteen consecutively treated surgical patients underwent an isolated modified hyoid suspension procedure to correct hypopharyngeal obstruction. Oropharyngeal‐palatal obstruction had previously been corrected or was thought not to be a component of the obstruction. Treatment outcomes were based on objective polysomnographic data and subjective clinical correction of excessive daytime sleepiness. The polysomnographlc data Included analysis of the respiratory disturbance index and lowest oxyhemoglobin desaturation. On the basis of these criteria, 12 of 15 patients (75%) had correction of their excessive daytime sleepiness and marked improvement in their sleep disorder breathing. The mean preoperative respiratory disturbance index was 44.7 ± 22.6, and the lowest oxyhemoglobin desaturation was 82% ± 6%. The postoperative respiratory disturbance index and lowest oxyhemoglobin desaturation were 12.8 ± 6.9 and 86% ± 5%, respectively. The modified hyoid suspension procedure appears to offer significant adjunctive treatment for hypopharyngeal obstruction in obstructive sleep apnea syndrome.
Computer‐Assisted Frontal Sinusotomy
Authors: Carrau Ricardo L. , Snyderman Carl H. , Curtin Hugh B. , Weissman Jane L.
Published: July 2017

An osteoplastic frontal sinus flap with flat obliteration is the “gold” standard for the management of chronic frontal sinus inflammatory disease caused by obstruction of the nasofrontal duct. Frontal sinusotomy, with an osteoplastic technique, call for osteotomies, guided by a template obtained from a Caldwell radiographic view taken at a distance of 6 feet. The reliability of the template depends on the position of the patient, distance at which the radiograph is taken, penetration of the x‐rays, and other technical aspects. Therefore the template is a potential source of error. We present the use of a computer‐assisted frontal sinusotomy as a method to corroborate the shape and margins of the frontal sinus in six patients undergoing obilterative frontal sinus surgery. In our hands, this technique has proved more reliable than the radiographic template to corroborate the positioning of the osteotomies.
Hemostatic Assessment of Patients before Tonsillectomy: A Prospective Study
Authors: Close Heidi L. , Kryzer Thomas C. , Nowlin John H. , Alving Barbara M.
Published: July 2017

The purpose of this prospective study in patients undergoing tonsillectomy was to determine whether perioperatve bleeding could be predicted by use of a standardized questionnaire concerning bleeding risk combined with measurement of the activated partial thromboplastin time and prothrombin time. Of the 96 patients enrolled in the study, none had a history of a severe bleeding disorder, but 6 (6%) had histories suggestive of a mild bleeding disorder. Further evaluation showed possible von Willebrand's disease in one of these patients. Of the 90 patients with negative questionnaires, 16% had prolongation of the activated partial thromboplastin time. One of these patients had possible von Willebrand's disease. However, none of the patients with positive questionnaires or a prolonged activated partial thromboplastin time bled after surgery. Bleeding that resulted in additional hospital use occurred in 2% of patients, and blood‐tinged sputum was described by 4% after discharge; all of these patients had negative questionnaires and normal screening studies. The data provide further evidence that routine measurement of the activated partial thromboplastin time and prothrombin time in asymptomatic patients is not useful for predicting postoperative bleeding. In addition, histories suggestive of a mild bleeding disorder are also not accurate predictors of postoperative bleeding. Excessive bleeding associated with tonsillectomy is usually not a result of an identifiable coagulation disorder.
Comparison of Computed Tomography and Surgical Findings in Deep Neck Infections
Authors: Lazor John B. , Cunningham Michael J. , Eavey Roland D. , Weber Alfred L.
Published: July 2017

Computed tomography is routinely used in the evaluation of patients suspected to have deep neck Infections. This 10‐year retrospective study compares preoperative computed tomography scan reports with intraoperative findings in 38 patients who underwent surgical exploration of the parapharyngeal or retropharyngeal space within 48 hours of their radiographic assessment. Overall, intraoperative findings confirmed computed tomography scan interpretation in 76.3% of the patients. The false‐positive rate was 13.2%, and the false‐negative rate was 10.5%. The sensitivity of computed tomography scan for detection of parapharyngeal space or retropharyngeal space abscess was 87.9%. This study's documentation of false‐positive computed tomography scans in the evaluation of deep neck infections emphasizes the importance of correlating radiologic interpretation with clinical examination before surgical intervention.
A Pressure‐Regulated Model of Normal and Pathologic Phonation
Authors: Nasri Sina , Namazie Ali , Kreiman Jody , Sercarz Joel A. , Gerratt Bruce R. , Berke Gerald S.
Published: July 2017

Recent evidence suggests that the lung‐thorax system functions as a constant pressure source during phonation. However, previous animal models used a constant flow source. This article describes an in vivo canine model that maintains a constant subglottic pressure during phonation to more closely simulate the pulmonary system. At any given subglottic pressure, increasing levels of recurrent laryngeal nerve stimulation resulted in a significant rise in resistance followed by a plateau. Increasing levels of superior laryngeal nerve stimulation, however, produced no significant change in glottal resistance. Three experimental conditions were studied: Normal, unilateral recurrent laryngeal nerve paralysis, and paralysis followed by arytenoid adduction. In normal canines, maximal vocal efficiency values were the highest, indicating the best match between pressure and resistance. The vocal efficiency values were significantly lower in recurrent laryngeal nerve paralysis, indicating pressure‐resistance mismatch. Arytenoid adduction increased the maximal vocal efficiency values and decreased the mismatch observed in the paralyzed state. These findings may provide insight into an understanding of normal and pathologic laryngeal behavior.
Numerical simulation and experimental research on the aerodynamic performance of large marine axial flow fan with a perforated blade
Authors: Yang Xinglin , Wu Chenhui , Wen Huabing , Zhang Linglong
Published: July 2017

In this study, some of the optimal parameters for a new-style marine axial flow fan are defined by using numerical simulation and experimental tests with a large marine axial flow fan, based on the analysis of the blade perforation’s influences on its internal flow field and aerodynamic noise characteristics. Test result shows that the noise reduction for the axial flow fan with perforated blade is about 3 dB when the blade perforation diameter D is 10 mm and its deflection angle α is 45°. The results of the study show that there is an inhibitory effect on the discrete noise of axial flow fan with perforated blade on the tip area, and its total noise level emerged as the fluctuated distribution characteristics with the increase in the perforation diameter D and reduced along with the increase in the deflection of perforation angle α, at the same time varied as a linear characteristics, which can be reasonably explained by the acoustic interference theory. The results of the study have also further confirmed that the improvement of the flow of axial flow fan with perforated blade helps to reduce the pressure pulsation amplitude caused by the turbulence of the blade surface boundary layer, thereby suppressing the back-flow and vortex from the pressure surface to the suction surface efficiently. It is indicated that the improved vortex shedding phenomenon at the blade trailing edge after perforation on the area of blade tip is the main reason for the aerodynamic noise reduction of axial flow fan.
Do the TOEFL iBT® section scores provide value-added information to stakeholders?
Authors: Sawaki Yasuyo , Sinharay Sandip
Published: July 2017

The present study examined the reliability of the reading, listening, speaking, and writing section scores for the TOEFL iBT® test and their interrelationship in order to collect empirical evidence to support, respectively, the generalization inference and the explanation inference in the TOEFL iBT validity argument (Chapelle, Enright, & Jamieson, 2008). By combining Haberman’s (2008) subscore analysis and confirmatory factor analysis (CFA), data from four operational TOEFL iBT test administrations were analyzed for all examinees and three major native language (L1) groups (Arabic, Korean, and Spanish). Key results were consistent across the forms and samples. First, Haberman’s (2008) subscore analysis suggested that the reliabilities of the section scores were generally satisfactory but for the writing section the reliability was relatively low. Second, Haberman’s subscore analysis and CFA offered different degrees of support for the distinctness of the TOEFL iBT section scores. A subsequent multiple-group CFA based on a correlated four-factor model generally supported the measurement invariance across the L1 groups in terms of factor loadings as well as indicator residuals and intercepts, despite the population heterogeneity indicated by the partial invariance of the latent factor variances and differences in the latent factor means across the groups. In addition, Haberman’s subscore analysis suggested that the speaking section score offered value-added information owing to its generally high level of reliability and relative distinctness from the other three section scores, which is relevant to the utilization inference in the validity argument from a perspective of psychometric quality of the TOEFL iBT section scores.
Sacred Destruction? Anticlericalism, Iconoclasm and the Sacralization of Politics in Twentieth-Century Spain
Authors: Thomas Maria
Published: July 2017

This article examines the ways in which anticlerical discourses and actions in Spain from the early twentieth century onwards became infused with religious language, sentiments and even belief. Specifically, it focuses on the anticlerical violence and iconoclasm which occurred on Republican territory at the beginning of the Spanish Civil War in 1936. The protagonists of these acts used a wide repertoire of religiously inspired collective action in their attacks on Catholic property and personnel. This article seeks to explain why this was. It argues that, in a time of momentous change and accelerating modernization, ‘secular’ and ‘traditional’ modes of thought mingled and fused together in the mental landscapes of anticlerical actors who had been strongly influenced by religious principles and practices. It suggests that the concept of the ‘sacralization of politics’ is wholly applicable to the Spanish case.
Caregiver burden in amyotrophic lateral sclerosis: A systematic review
Authors: de Wit Jessica , Bakker Leonhard A , van Groenestijn Annerieke C , van den Berg Leonard H , Schröder Carin D , Visser-Meily Johanna MA , Beelen Anita
Published: July 2017

Background:

Informal caregivers of patients with amyotrophic lateral sclerosis experience increased levels of caregiver burden as the disease progresses. Insight in the factors related to caregiver burden is needed in order to develop supportive interventions.

Aim:

To evaluate the evidence on patient and caregiver factors associated with caregiver burden in amyotrophic lateral sclerosis informal caregivers.

Design:

A systematic review.

Data sources:

Four electronic databases were searched up to 2017. Studies that investigated quantitative relations between patient or caregiver factors and caregiver burden were included. The overall quality of evidence for factors was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach.

Results:

A total of 25 articles were included. High quality of evidence was found for the relation between caregiver burden and the factor “behavioral impairments.” Moderate quality of evidence was found for the relations between caregiver burden and the factors “feelings of depression” of the caregiver and “physical functioning” of the patient. The remaining rated caregiver factors—“feelings of anxiety,” “distress,” “social support,” “family functioning,” and “age”—and patient factors—“bulbar function,” “motor function,” “respiratory function,” “disease duration,” “disinhibition,” “executive functioning,” “cognitive functioning,” “feelings of depression,” and “age”—showed low to very low quality of evidence for their association with caregiver burden.

Conclusion:

Higher caregiver burden is associated with greater behavioral and physical impairment of the patient and with more depressive feelings of the caregiver. This knowledge enables the identification of caregivers at risk for caregiver burden and guides the development of interventions to diminish caregiver burden.
Supporting carers to manage pain medication in cancer patients at the end of life: A feasibility trial
Authors: Latter Sue , Hopkinson Jane B , Lowson Elizabeth , Hughes Jane A , Hughes Jacki , Duke Sue , Anstey Sally , Bennett Michael I , May Carl , Smith Peter , Richardson Alison
Published: July 2017

Background:

Carers of people with advanced cancer play a significant role in managing pain medication, yet they report insufficient information and support to do so confidently and competently. There is limited research evidence on the best ways for clinicians to help carers with medication management.

Aims:

To develop a pain medicines management intervention (Cancer Carers Medicines Management) for cancer patients’ carers near the end of life and evaluate feasibility and acceptability to nurses and carers. To test the feasibility of trial research procedures and to inform decisions concerning a full-scale randomised controlled trial.

Design:

Phase I-II clinical trial. A systematic, evidence-informed participatory method was used to develop CCMM: a nurse-delivered structured conversational process. A two-arm, cluster randomised controlled feasibility trial of Cancer Carers Medicines Management was conducted, with an embedded qualitative study to evaluate participants’ experiences of Cancer Carers Medicines Management and trial procedures.

Setting:

Community settings in two study sites.

Participants:

Phase I comprises 57 carers, patients and healthcare professionals and Phase II comprises 12 nurses and 15 carers.

Results:

A novel intervention was developed. Nurses were recruited and randomised. Carer recruitment to the trial was problematic with fewer than predicted eligible participants, and nurses judged a high proportion unsuitable to recruit into the study. Attrition rates following recruitment were typical for the study population. Cancer Carers Medicines Management was acceptable to carers and nurses who took part, and some benefits were identified.

Conclusion:

Cancer Carers Medicines Management is a robustly developed medicines management intervention which merits further research to test its effectiveness to improve carers’ management of pain medicines with patients at the end of life. The study highlighted aspects of trial design that need to be considered in future research.
National palliative care capacities around the world: Results from the World Health Organization Noncommunicable Disease Country Capacity Survey
Authors: Sharkey Lee , Loring Belinda , Cowan Melanie , Riley Leanne , Krakauer Eric L
Published: July 2017

Background:

Previous estimates of global palliative care development have not been based on official country data.

Aim:

The World Health Organization Noncommunicable Disease Country Capacity Survey of World Health Organization member state officials monitors countries’ capacities for the prevention and control of noncommunicable diseases. In 2015, for the first time, questions were included on a number of palliative care development metrics to generate baseline data for monitoring global palliative care development.

Design:

Participants were given instructions, a glossary of terms, and 3 months to complete this closed, non-randomized, online survey. Questions were developed through a consultative process with relevant technical World Health Organization departments.

Setting/participants:

Health ministry officials serving as noncommunicable disease focal points from 177 out of 194 (91%) of World Health Organization Member States completed the voluntary survey.

Results:

This survey reveals that (a) a minority (37%) of countries have an operational national policy for noncommunicable diseases that includes palliative care, (b) palliative care is least likely to have funding available compared with other core noncommunicable disease services, and (c) there is a large country-income gradient for palliative care funding, oral morphine availability, and integration of palliative care services at the primary levels of the health system.

Conclusion:

Palliative care for noncommunicable disease patients must be strengthened in a majority of countries. These data provide a baseline for trend measurement of official country-level and global palliative care development. A repeat assessment is taking place in the first half of 2017.
Implantable cardioverter defibrillator knowledge and end-of-life device deactivation: A cross-sectional survey
Authors: McEvedy Samantha M , Cameron Jan , Lugg Eugene , Miller Jennifer , Haedtke Chris , Hammash Muna , Biddle Martha J , Lee Kyoung Suk , Mariani Justin A , Ski Chantal F , Thompson David R , Chung Misook Lee , Moser Debra K
Published: July 2017

Background:

End-of-life implantable cardioverter defibrillator deactivation discussions should commence before device implantation and be ongoing, yet many implantable cardioverter defibrillators remain active in patients’ last days.

Aim:

To examine associations among implantable cardioverter defibrillator knowledge, patient characteristics and attitudes to implantable cardioverter defibrillator deactivation.

Design:

Cross-sectional survey using the Experiences, Attitudes and Knowledge of End-of-Life Issues in Implantable Cardioverter Defibrillator Patients Questionnaire. Participants were classified as insufficient or sufficient implantable cardioverter defibrillator knowledge and the two groups were compared.

Setting/participants:

Implantable cardioverter defibrillator recipients ( n = 270, mean age 61 ± 14 years; 73% male) were recruited from cardiology and implantable cardioverter defibrillator clinics attached to two tertiary hospitals in Melbourne, Australia, and two in Kentucky, the United States.

Results:

Participants with insufficient implantable cardioverter defibrillator knowledge ( n = 77, 29%) were significantly older (mean age 66 vs 60 years, p = 0.001), less likely to be Caucasian (77% vs 87%, p  = 0.047), less likely to have received implantable cardioverter defibrillator shocks (26% vs 40%, p = 0.031), and more likely to have indications of mild cognitive impairment (Montreal Cognitive Assessment score <24: 44% vs 16%, p < 0.001). Insufficient implantable cardioverter defibrillator knowledge was associated with attitudes suggesting unwillingness to discuss implantable cardioverter defibrillator deactivation, even during the last days towards end of life ( p < 0.05).

Conclusion:

Implantable cardioverter defibrillator recipients, especially those who are older or have mild cognitive impairment, often have limited knowledge about implantable cardioverter defibrillator deactivation. This study identified several potential teachable moments throughout the patients’ treatment trajectory. An interdisciplinary approach is required to ensure that discussions about implantable cardioverter defibrillator deactivation issues are initiated at appropriate time points, with family members ideally also included.
Is intervertebral disc degeneration related to segmental instability? An evaluation with two different grading systems based on clinical imaging
Authors: Volkheimer David , Galbusera Fabio , Liebsch Christian , Schlegel Sabine , Rohlmann Friederike , Kleiner Sebastian , Wilke Hans-Joachim
Published: July 2017

Background

Several in vitro studies investigated how degeneration affects spinal motion. However, no consensus has emerged from these studies.

Purpose

To investigate how degeneration grading systems influence the kinematic output of spinal specimens.

Material and Methods

Flexibility testing was performed with ten human T12-S1 specimens. Degeneration was graded using two different classifications, one based on X-ray and the other one on magnetic resonance imaging (MRI). Intersegmental rotation (expressed by range of motion [ROM] and neutral zone [NZ]) was determined in all principal motion directions. Further, shear translation was measured during flexion/extension motion.

Results

The X-ray grading system yielded systematically lesser degeneration. In flexion/extension, only small differences in ROM and NZ were found between moderately degenerated motion segments, with only NZ for the MRI grading reaching statistical significance. In axial rotation, a significant increase in NZ for moderately degenerated segments was found for both grading systems, whereas the difference in ROM was significant only for the MRI scheme. Generally, the relative increases were more pronounced for the MRI classification compared to the X-ray grading scheme. In lateral bending, only relatively small differences between the degeneration groups were found. When evaluating shear translations, a non-significant increase was found for moderately degenerated segments. Motion segment segments tended to regain stability as degeneration progressed without reaching the level of statistical significance.

Conclusion

We found a fair agreement between the grading schemes which, nonetheless, yielded similar degeneration-related effects on intersegmental kinematics. However, as the trends were more pronounced using the Pfirrmann classification, this grading scheme appears superior for degeneration assessment.
Therapeutic Climate Within a Treatment Program for Categorical Deniers
Authors: Ware Jayson
Published: July 2017

The purpose of this study was to examine whether the therapeutic climate within a sex offender “deniers” program, where denial was not challenged, would be equivalent to the therapeutic climate within a conventional program where sex offenders were admitting responsibility. Using a sample of 77 sex offenders, therapeutic alliance and group climate were measured early and late in treatment. As expected, therapeutic alliance was more difficult to attain with deniers early in treatment, particularly therapeutic bond; however, by the end of the treatment, there were no significant differences in therapeutic alliance. There did not appear to be significant differences in group climate early or late in treatment except for the deniers reporting significantly lower levels of open expression of anger and disagreement within the group and, in contrast to the admitters, making significant improvements in group climate over time. Implications for the treatment of categorical deniers and further research suggestions are discussed.
Producing an urban hazardscape beyond the city
Authors: Saguin Kristian
Published: July 2017

Urban socioecological risk, like other urban metabolic processes, embodies relations between the city and the non-city. In this paper, I trace the production of urban risk within and beyond the city through the lens of the hazardscape using the case of Metro Manila and Laguna Lake in the Philippines. Building on recent interventions in urban political ecology that seek to map the terrains of extending urban frontiers, I examine the processes that construct city and non-city spaces in urbanization through flood control. I synthesize narratives of the material-discursive production of risk mediated by infrastructure with histories of landscape and livelihood change in an urban socioecological frontier to make two related arguments. First, discursive constructions of city and non-city and the material flows that connect them shape the production of urban ecological risk, with material consequences for non-city vulnerabilities. Second, infrastructure plays an important mediating role in the production of hazardscapes. The intersection of flows of water, discursive urban imaginaries in state plans, and livelihoods in Metro Manila and Laguna Lake exemplifies metabolic relations that reveal the spatio-temporal connections of cities with landscapes that make their functioning possible.
Reproducibility of migraine-like attacks induced by phosphodiesterase-3-inhibitor cilostazol
Authors: Khan Sabrina , Deen Marie , Hougaard Anders , Amin Faisal Mohammad , Ashina Messoud
Published: July 2017

Introduction

The phosphodiesterase-3-inhibitor cilostazol induces migraine-like attacks in patients with migraine without aura, and may be used as a pharmacological trigger in human experimental models of migraine. However, the reproducibility of cilostazol-induced migraine-like attacks has never been investigated.

Methods

We performed a post-hoc analysis of clinical data from two brain-imaging studies including subjects who had received cilostazol 200 mg orally. Only subjects who developed migraine-like attacks on study day 1 were included on study day 2. After cilostazol ingestion, subjects and the investigator recorded headache intensity and characteristics once every hour on a purpose-developed questionnaire. Primary end-points included incidence and time to onset of migraine-like attacks between two separate study days.

Results

Thirty-four subjects completed both experimental days and were included in this study. Thirty-four out of 34 subjects (100%) developed migraine-like attacks after cilostazol ingestion on both study days 1 and 2. Time to onset of migraine was five hours (range 1–8 hours) on study day 1 and four hours (range 1–8 hours) on study day 2, p = 0.16. We found no difference in median peak headache score, median time to peak headache score, or median time to intake of rescue medication between study days 1 and 2.

Conclusion

A second-time administration of cilostazol reproduces migraine-like attacks in all subjects who report an attack after their first cilostazol induction. There was no difference in time to migraine onset between separate inductions. Experimental migraine provocation using cilostazol is a highly efficient and useful approach for studying the ictal phase of migraine without aura.
Return-to-Play Guidelines After Medial Patellofemoral Ligament Surgery for Recurrent Patellar Instability: A Systematic Review
Authors: Zaman Saif , White Alex , Shi Weilong J. , Freedman Kevin B. , Dodson Christopher C.
Published: July 2017

Background:

Medial patellofemoral ligament (MPFL) reconstruction and repair continue to gain acceptance as viable treatment options for recurrent patellar instability in patients who wish to return to sports after surgery. Return-to-play guidelines with objective or subjective criteria for athletes after MPFL surgery, however, have not been uniformly defined.

Purpose:

To determine whether a concise and objective protocol exists that may help athletes return to their sport more safely after MPFL surgery.

Study Design:

Systematic review.

Methods:

The clinical evidence for return to play after MPFL reconstruction was evaluated through a systematic review of the literature. Studies that measured outcomes for isolated MPFL surgery with greater than a 12-month follow-up were included in our study. We analyzed each study for a return-to-play timeline, rehabilitation protocol, and any measurements used to determine a safe return to play after surgery.

Results:

Fifty-three studies met the inclusion criteria, with a total of 1756 patients and 1838 knees. The most commonly cited rehabilitation guidelines included weightbearing restrictions and range of motion restrictions in 90.6% and 84.9% of studies, respectively. Thirty-five of 53 studies (66.0%) included an expected timeline for either return to play or return to full activity. Ten of 53 studies (18.9%) in our analysis included either objective or subjective criteria to determine return to activity within their rehabilitation protocol.

Conclusion:

Most studies in our analysis utilized time-based criteria for determining return to play after MPFL surgery, while only a minority utilized objective or subjective patient-centric criteria. Further investigation is needed to determine safe and effective guidelines for return to play after MPFL reconstruction and repair.
Modeling of In-Plane Shear Modulus of Composite Materials for Aerospace Applications
Authors: Munro M. , Lee S.
Published: July 2017

An evaluation of micromechanical models for predicting the in-plane shear modulus, G,2, of five composite materials for aerospace applications has been carried out for three test methods (10° off-axis tensile, -45O tensile and 900 Iosipescu). Seven existing micromechanical models predicted similar trends, however, they did not accurately predict the experimental results. The use of mathematically simplified micromechanical models containing only G,m and V. resulted in values within 10% of those for the original models. This led to the development of individual, simplified design-oriented expressions of the form:

[ILLEGIBLE]

for which the predicted results are in better agreement with the experimentally determined values than those of the existing micromechanical models.
Effects of Mode Ratio, Ply Orientation and Precracking on the Delamination Toughness of a Laminated Composite
Authors: Polaha J. J. , Davidson B. D. , Hudson R. C. , Pieracci A.
Published: July 2017

Results are presented from an investigation of the effects of mode ratio, interfacial ply orientation and precracking on the delamination toughness of a graphite/ epoxy composite. Delamination toughness tests were performed on specimens that exhibited growth at 00/00, 15°/15°, 15°/- 150, 30°/30° and 30°/-30° interfaces. Three mode ratios were considered. The double cantilever beam test was utilized for pure mode I, the end-notched flexure test was used for pure mode II, and the symmetrically delaminated single leg bending test was used for a mixed-mode condition, G,,IG, equal to approximately 0.4. All five interfaces were tested in both precracked and non-precracked conditions at each mode ratio. Also, for the 30°/30° and 30°/- 30° interfaces, two different stacking sequences were used to assess the effect of remote ply orientation on the perceived mode I and mode II toughness. For any mode ratio and interface angle, it was found that precracked toughness values were always lower than the corresponding nonprecracked result. No other consistent trends were observed in all of the data. For the mode I tests, the 30/30 interface exhibited the lowest toughness, for the mixed-mode tests, the 0/0 interface produced a minimum toughness, and for mode II no significant effect of interface angle on toughness was observed. These results are interpreted with the aid of recent three dimensional finite element analyses for energy release rate distributions along the delamination front for the different stacking sequences and test geometries. The accuracy of various data reduction techniques are also evaluated, and suggestions are made for future testing.
Fatigue Degradation and Life Prediction of Glass Fabric Polymer Composite under Tension/Torsion Biaxial Loadings
Authors: Kawakami Hiroshi , Fujii Toru J. , Morita Yusuke
Published: July 2017

Fatigue degradation and life prediction for a plain woven glass fabric reinforced polyester under tension/torsion biaxial loadings were investigated. Typical S-N diagrams were given at several biaxial ratios when the biaxial cyclic loads were proportionally applied to the specimens. A fatigue damage accumulation model based on the continuum damage mechanics theory was developed, where modulus decay ratios in tension and shear were used as indicators for damage variables D. In the model, the damage variables are considered to be second-order tensors. Then, the maximum principal damage variable, D* is introduced. According to the similarity to the principal stress, D* is obtained as the maximum eigenvalue of damage tensor [D']. Under proportional tension/torsion loadings, fatigue lives were satisfactorily predicted at any biaxial stress ratios using the present model in which the fatigue characteristics only under uniaxial tension and pure torsion loadings were needed. For a certain biaxial stress ratio, the effect of loading path on the fatigue strength was examined. The experimental result does not show a strong effect of loading path on the fatigue life.
Optimization of Stresses in the End-Fittings of Composite Insulators for Distribution and Transmission Lines
Authors: Lanteigne J. , Lalonde S. , De Tourreil C.
Published: July 2017

This paper addresses the problem of stress calculation and optimization in a FRP (Fibre-glass Reinforced Plastic) pultruded rod crimped into a metal end-fitting. This type of assembly is used mainly for suspension and line post insulators. We discuss herein some aspects that merit consideration in any given design approach. In many respects FRP pultruded materials are anisotropic. The anisotropy of their elastic constants influences the distribution of stresses while the anisotropy of their mechanical properties (ultimate strengths) limits their load carrying capacity. Finally, the anisotropy of their failure modes governs the progression and the spread of the damage. Each level of anisotropy will be discussed distinctly.

Geometrical considerations are also necessary to arrive at an efficient design. Namely, we will consider the frictional interactions between the end-fitting inner wall and the rod, then we will present our approach in selecting the appropriate LID ratio (i.e., the ratio of the end-fitting length over the rod diameter), and finally we will discuss the influence of the compression profile, i.e., the permanent radial displacement imparted to the rod due to the action of the crimping force.
Building of a Composite Transmission Tower
Authors: Yeh Hsein-Yang , Yang Samuel C.
Published: July 2017

This paper will study the feasibility of building a transmission tower from a composite material, E-glass and Vinylester. The tower was fabricated using a fabrication process called pultrusion. Also instead of using the conventional fastener method to join the cross members to the leg members, the design team utilized a slip joint that was developed by Goldsworthy Engineering

The lamina of the leg member and the cross bracing were tested and compared with two analytical failure criteria, Yeh-Stratton Criterion and Quadratic (strain space) Criterion. In addition to ply failure analysis a full scale tower tests were performed at Electrical and Power Research Institute.
Property Degradation of Anisotropic Composite Laminates with Matrix Cracking. Part 2: Determination of Resolved Stiffness and Numerical Study of Stiffness Degradation
Authors: Yu Hua , Xingguo Wang , Zhengneng Li , Qingzhi He
Published: July 2017

The study on property degradation of damaged composite laminates is extended to anisotropic laminates with matrix cracking. In Part 2 of the paper, a solution for partitioned stiffnesses is given to complete the constitutive relations developed in Part 1. The stiffness degradation in (0,,, /90,,), cracked laminates are calculated and the results are discussed.
The Use of Three-Dimensional Computational Fluid Dynamics in the Design of Extrusion Dies
Authors: Gifford W. A.
Published: July 2017

With the proper use of three-dimensional computational fluid dynamics (CFD), the design of extrusion dies can be taken from that of an art to a science. Although replacing simpler traditional one- and two-dimensional approaches with fully three-dimensional ones requires a much more in depth analysis and a large amount of computations, the design of most dies can be performed on a personal computer. This paper demonstrates how these techniques are being used to obtain optimized designs of extrusion dies.
Nondestructive Evaluation and Characterization of Microfibers Modified Textile Carbon-Phenolic and Carbon-Carbon Composites
Authors: Vaidya U. K. , Dadzie Peter-Eshun , Haque A. , Mahfuz H. , Jeelani S.
Published: July 2017

Short carbon microfibers have been added to carbon-phenolic fabric composites of plain, eight-harness satin (8HS) and stretch broken 8HS weave architectures. The resulting composites have been studied for their interlaminar mechanical properties as well as process related material evolution mechanisms that result in carbon-carbon (C-C) composites. Dry coupling ultrasonic A-scan velocity measurements, immersion type ultrasonic C-scan technique, acousto-ultrasonic (AU) stress wave factor measurements and vibration damping ratio based nondestructive evaluation-characterization (NDE-C) test parameters were studied in relation to the carbon-phenolic and C-C composites. Interlaminar shear strength (ILSS) tests were conducted along with acoustic emission (AE) monitoring. From the various NDE techniques accompanied by mechanical tests and processing stages, the dependence of fabric weave architectures with short microfibers has been established.
Acid Resistance of Glass Fibre Composites with Different Layup Sequencing: Part I-Diffusion Studies
Authors: Pai Raghavendra , Kamath M. S. , RAO R. M. V. G. K.
Published: July 2017

The effects of sulphuric acid concentration and the sequential layup of glass fibre reinforcements on the diffusion behaviour of glass epoxy composite laminates were studied. In all, composites of six different resin systems viz., general purpose polyester, bis phenol-A polyester, vinyl ester, LY 556 epoxy, and MY 750 epoxy resins, reinforced with different layup sequencing consisting of chopped strand mat (CSM) and woven roving mat (WR) were exposed to sulphuric acid environments of different concentrations.

The results of the study indicated that isophthalic polyester resin exhibited maximum resistance to sulphuric acid while general purpose polyester resin performed relatively inferior. The diffusion phenomenon became anamalous as the concentration of the sulphuric acid increased. Among the layup sequences considered, composite specimens with CSM as the skin layers exhibited higher weight gain than those with WR as the skin layers.
A Probabilistic Progressive Failure Model of Composite Laminates
Authors: Mahadevan S. , Liu X. , Xiao Q.
Published: July 2017

This paper investigates the strength failure of composite laminates using system reliability theory. A probabilistic progressive failure model of composite laminates is proposed. The overall failure of the laminate is caused by a series of ply-level failure events. There exist many possible failure sequences of ply-level events that lead to overall laminate failure. Matrix cracking and fiber breakage are defined as the two basic failure events of each ply and a damage-modification technique is adopted to simulate the system progressive failure process. The first-order reliability method (FORM) is employed to compute the filure probability of the ply-level events. A search technique based on the branch-and-bound concept is developed to identify the significant fiilure sequences. The system failure probability is computed using reliability bounding techniques.
On the Effective Moduli of Anisotropic Composites with Aligned Ellipsoidal Inclusions
Authors: Demakos C. B.
Published: July 2017

The effective elastic and shear moduli of a 3-D composite containing aligned ellipsoidal inclusions are evaluated in this paper. The material considered is transversely isotropic due to the uniform dispersion of inclusions in plane sections normal to their major axis.

The method followed for the solution of the problem is based upon Eshelby's theory. We evaluate the strain field around a single ellipsoidal inhomogeneity surrounded by the effective anisotropic medium. Considering the mutual interaction of the neighbouring inclusions inside the matrix, we may evaluate the effective stiffness of composites with inclusions at dilute concentrations by using Mori-Tanaka's concept. The parameters involved in the analysis are the aspect ratio of the inclusions, their volume fraction and the ratio of the elastic moduli of the constituent phases forming the composite.

The results show that the anisotropy of the composite is rather affected by the hardness of the inclusions relatively to the matrix than by the aspect ratio of inclusions. On the other hand, the stiffness of the composite is rather greater in models with inclusions of a needleshape form than in composites with spheroidal inclusions.
Stress Relaxation Behavior of Short Pineapple Fiber Reinforced Polyethylene Composites
Authors: George Jayamol , Sreekala M. S. , Thomas Sabu , Bhagawan S. S. , Neelakantan N. R.
Published: July 2017

Stress relaxation behavior of short pineapple fiber reinforced polyethylene composites in tension has been studied with special reference to the effect of fiber loading, fiber length, chemical treatment and fiber orientation. Chemical treatments of fiber with reagents such as isocyanate, silane, alkali and peroxide were carried out to improve the interface adhesion between fiber and matrix. The effects of strain level, chemical treatments, pre-straining, and aging on the rate of relaxation have been investigated. It was found that the stress relaxation rate decreases with strain level. It was found that incorporation of fiber results in two relaxation processes. The rate of relaxation is decreased with fiber content. It is observed that chemical treatment has significant influence on the relaxation behavior. Composites containing fibers oriented longitudinally have higher relaxation rate than transversely oriented composites. Aging of samples improved the relaxation modulus due to improved interfacial adhesion at higher temperature. It has been demonstrated that the stress relaxation modulus values measured at different strains can be superimposed by a shift along the logarithmic time axis to yield master curves of modulus over an extended time period.
Comparative Evaluation of Impact Performance of Laminate Composites Containing Impact Induced/Mechanically Inserted Defects
Authors: Khan B.
Published: July 2017

The low mass, low energy pendulum impact on carbon-epoxy (C-E) composite system under varied conditions are reported in this work. While in one case repeated low mass impacts were followed by a single higher mass impact leading to failure, in others, between these two impact events, slits of depth 1 mm, 3 mm and 5 mm were introduced. Also, in one experiment a variation in the programme involved a 45° notch being inserted instead of the slits. Fracture features were also examined using a light microscope.

For the case of unnotched specimens, the investigation points to a maximum energy absorption and a fracture surface which is grooved with a rough terrain. The data, on the other hand, point to a minimum energy absorption and a comparatively flat feature for the fractured surface for the case of 5 mm slit introduced specimen. Samples with other depths of slits showed features that lie in between these two extremes.
Effect of Resin Interlayer on Fracture Behavior of Composite Laminates
Authors: Hu H. , Abatan A.
Published: July 2017

In this work, the effect of resin interlayer on the fracture behavior of composite laminates is evaluated. For cracks in elastic laminates, the closed-form solutions for energy release rate and mode ratio are presented. These solutions are applicable to structures where classical laminated plate theory may be used to predict deflections and strain energies. For a typical graphite/epoxy composite laminate containing a free edge delamination bounded by an isotropic resin interlayer, it is found that the energy release rate is not sensitive to the Young's modulus of the resin interlayer, but the mode ratio is very sensitive. However, the energy release rate is insensitive to the Poisson's ratio of the resin interlayer. It is also found that within a certain range, the thickness of the resin interlayer does not have much effect on the energy release rate. The limitations of the current results are the assumption of elastic deformation and the applicability of classical laminated plate theory.
Mode II Interlaminar Crack Growth Process in Polymer Matrix Composites
Authors: Lee Shaw Ming
Published: July 2017

The mode II interlaminar crack growth process in polymer matrix composites is studied by focusing on the underlying microscopic failure mechanisms. A recently developed mode II failure model based on fracture mechanics principles is used to analyze a wide range of failure phenomena. Examined in detail is how hackles or microcracks typifying the failure process are induced or in some cases suppressed. The crack tip stresses controlling the crack growth are found to be highly dependent on fiber arrangement and resin content. Resin microcracking at the crack tip is mode I in nature and can be overcome by resin yielding depending on the resin variables involved. Multiple microcrack formation with regular spacing is controlled by a shear lag effect often influenced by resin plastic deformation for even brittle resins. Such microcrack spacing affects the stress distribution leading to microcrack coalescence and thus crack propagation. From the failure process described, laminate mode II fracture toughness G11C can be quantitatively expressed as a function of resin properties (fracture toughness GIc, yield strength τy, and shear modulus G), reflecting the underlying resin deformation/fracture mechanisms. Fiber arrangement is found to uniquely affect the hackle pattern in a way consistent with the identified failure mechanisms. Temperature and loading rate effects on Guj C are also well interpreted by the identified failure mechanisms. This study further elucidates the crack growth process of mode II interlaminar failure.