bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Haemodilution with Succinylated Gelatin Solution on Coagulation in Vitro as Assessed by Thromboelastometry and Impedance (Multiple Electrode) Aggregometry
Authors: Kam P. C. A. , Varanasi S. , Yang K. X.
Published: January 2019

We investigated the in vitro viscoelastic changes of progressive haemodilution with succinylated gelatin (SG) solution compared with normal saline (NS) using rotational thromboelastometry (ROTEM®). Whole blood (WB) samples obtained from 20 healthy volunteers were diluted in vitro with SG solution or NS by 10%, 20% and 40%. Fibrinogen concentration and ROTEM (EXTEM, FIBTEM) variables including coagulation time (CT), clot formation time (CFT), α-angle, and maximum clot firmness (MCF) were measured in the undiluted sample and at each degree of haemodilution. Haemodilution with SG decreased FIBTEM MCF by 34.8% at 20% dilution (SG 20% haemodilution mean 9.1 [standard deviation, SD 2.7] mm versus WB, mean 13.9 [SD 3.4] mm) whereas this was observed only at 40% haemodilution with NS (mean 8.5 [SD 2.7] mm, 38.7% decrease). We found that 40% haemodilution with SG slowed clot formation (EXTEM CFT; SG 40%, mean 179 [SD 39] seconds versus WB mean 87.9 [SD 13.7] seconds; increased CFT by 103%), reduced clot strength by 23.5% (EXTEM MCF; SG 40% mean 47.7 [SD 3.4] mm versus WB mean 62.4 [SD 2.5] mm), and decreased fibrin formation (FIBTEM MCF; SG 40% mean 5.8 [SD 1.6] mm versus WB mean 13.9 [SD 3.4] mm); 58.4% decrease). The platelet contribution to clot strength (EXTEM MCF–FIBTEM MCF) was not changed by SG. We found that haemodilution of more than 20% with SG impaired coagulation greater than that observed with NS haemodilution in this in vitro study. This suggests that at 40% haemodilution with SG, a clinical scenario that could occur during resuscitation of a patient in grade IV haemorrhagic shock, impaired coagulation could occur. Frequent monitoring of coagulation is advised when SG solutions are administered rapidly during volume resuscitation.
Non-Invasive Estimation of Cardiac Index in Healthy Volunteers
Authors: Eyeington C. T. , Ancona P. , Cioccari L. , Luethi N. , Glassford N. J. , Eastwood G. M. , Proimos H. K. , Franceschi F. , Chan M. J. , Jones D. , Bellomo R.
Published: January 2019

The primary objective was to non-invasively measure the cardiac index (CI) and associated haemodynamic parameters of healthy volunteers and their changes with age. This was a single centre, prospective, observational study of healthy volunteers aged between 20 and 59 years, using the ClearSight™ (Edwards Life Sciences, Irvine, CA, USA) device. We recorded 514 observations in 97 participants. The mean CI was 3.5 l/min/m2 (95% confidence interval [95% CI] 3.4 to 3.7 l/min/m2). The mean stroke volume index (SVI) was 47 ml/m2 (95% CI 45 to 49 ml/m2) and the mean systemic vascular resistance index was 2,242 dyne·s/cm5/m2 (95% CI 2,124 to 2,365 dyne·s/cm5/m2). There was an inverse linear relationship between increasing age and CI (P <0.0001), which decreased by 0.044 l/min/m2 (95% CI −0.032 to −0.056 l/min/m2) per year. This change was mostly due to a decrease in SVI of 0.45 ml/m2 (95% CI 0.32 to 0.57 ml/m2) per year (P <0.0001). The mean CI of young healthy humans is approximately 3.5 l/min/m2 and declines by approximately 40 ml/min/m2 per year, mostly due to a decline in stroke volume (SV). These findings have significant implications regarding the clinical interpretation of haemodynamic parameters and the application of these results to individual patients.
Clinical Practice Variation in Acute Severe Burn Injury
Authors: Garside T. L. , Lee R. P. , Delaney A. , Milliss D.
Published: January 2019

The New South Wales (NSW) Statewide Burn Injury Service Database was reviewed to identify variations in clinical practice with respect to care of severely burn-injured patients in intensive care. We compared differences in practice relating to duration of endotracheal intubation and surgical grafting. In this retrospective observational study, we reviewed all intensive care unit (ICU) admissions to the two NSW adult burns centres, ICU A and ICU B, between January 2008 and December 2015. Data were analysed for association between duration of intubation and outcome. There were 855 admissions to adult ICU, with a significant difference in the percentage total body surface area (% TBSA) of burn and inhalation injury between patients in the two units. There was a significant difference in duration of intubation and ICU length of stay (LOS) between the units, which persisted when adjusted for age, % TBSA and inhalational injury. When analysing patients with more severe burns (>20% TBSA or intubated), the difference in duration of intubation remained significant (median of three days [interquartile range, IQR, 1–11 days] in A and 2 days [IQR 1–6 days] in B, P=0.003) as did ICU LOS (median 3 days [IQR 2–11 days] for A and 2 days [IQR 1–6 days] for B, P <0.0005). There was no significant difference in mortality between the two units for the severe or the more severe subgroup of burns when adjusted for age, % TBSA and inhalational injury (adjusted odds ratio, OR, for mortality 1.17 [95% confidence intervals 0.6 to 2.3, P=0.65]). There were significant differences in clinical practice, including duration of intubation, between the two ICUs. Longer intubation was associated with a longer ICU LOS, but was not associated with a difference in mortality. Large collaborative, prospective multicentre studies in severe burns are needed to identify best practice and variations in practice to determine if they are associated with increased mortality and/or cost.
A Prospective Observational Study of the Change in Systemic Ionised Calcium following 4% Citrate Locking of Venous Haemodialysis Catheters in Intensive Care Patients
Authors: Shewdin S. , Bong Y. C. , Okano S. , Chatfield M. D. , Walsham J.
Published: January 2019

Traditionally heparin has been the anticoagulant of choice for venous dialysis catheter locking. There is systemic leakage of heparin catheter locking solutions at the time of injection. Alternative agents, such as citrate, are increasingly being used. We are not aware of any data in the critical care literature on the effect of citrate locking of venous dialysis catheters on systemic ionised calcium (iCa2+). To assess the effect of 4% citrate locking of venous dialysis catheters on systemic iCa2+ in intensive care patients we performed a prospective observational study of 50 paired samples in 26 intensive care patients receiving 4% citrate dialysis catheter locking in an adult tertiary intensive care unit between May 2016 and December 2016. Arterial blood gas (ABG) analysis was performed prior to venous dialysis catheter locking and a baseline iCa2+ result obtained. The catheter was locked with 4% citrate solution. A further ABG was sampled between 30 and 120 seconds later and the iCa2+ results were compared. Patients were observed for clinical signs of hypocalcaemia. On average, there was little difference between the pre- and post-catheter locking iCa2+ (median pre-locking iCa2+ 1.19 mmol/l, mean change of +0.004 mmol/l, 95% confidence interval [CI] −0.004 to 0.013, P=0.34). There was no evidence this difference differed by length of catheter (P=0.26) or site of catheter (P=0.85) insertion, but there was some evidence that this differed by receipt of citrate dialysis circuit anticoagulation (P=0.013). Patients who received citrate dialysis circuit anticoagulation had an increase in catheter locking iCa2+ by 0.017 mmol/l (95% CI 0.005 to 0.028). Locking of venous dialysis catheters with 4% citrate solution has no clinically significant effect on systemic iCa2+ in intensive care patients with indwelling venous dialysis catheters.
Survey of Occupational Fatigue in Anaesthetists in Australia and New Zealand
Authors: Stuetzle K. V. , Pavlin B. I. , Smith N. A. , Weston K. M.
Published: January 2019

Occupational fatigue in anaesthetists is recognised as a patient safety risk. Better understanding of the issues surrounding their fatigue is needed. This study aimed to ascertain the sources and effects of occupational fatigue amongst anaesthetists in Australia and New Zealand. An anonymous online survey was sent to 979 anaesthetists. The response rate was 38.0%. Most participants reported regularly working over 40 hours per week; men reported five more hours per week than women. Stated contributors to fatigue included long work hours, mental strain at work, and personal and family demands. Fatigue-related behaviour was reported more by men (OR [odds ratio]=2.6) and less by respondents reporting eight or more hours of sleep before work (OR=0.6). Reporting at least one instance of less than five hours off between shifts was predictive of falling asleep while administering an anaesthetic (OR=1.6). More data are required to support practices and policies that promote more time off between work periods and increased time for sleep to reduce risk of fatigue.
Nutritional Prehabilitation: Physiological Basis and Clinical Evidence
Authors: Pillinger N. L. , Robson J. L. , Kam P. C. A.
Published: January 2019

In this narrative review, we describe the physiological basis for nutritional prehabilitation and evaluate the clinical evidence for its current roles in the perioperative period. Surgical stress and fasting induce insulin resistance as a result of altered mitochondrial function. Insulin resistance in the perioperative period leads to increased morbidity in a dose-dependent fashion, while preoperative carbohydrate loading attenuates insulin resistance, minimises protein loss and improves postoperative muscle function. Carbohydrate loading is an established practice in many countries and a key component of enhanced recovery after surgery (ERAS) programs, yet its independent effects on clinical outcomes remain unclear. Amino acid supplements may confer additional positive effects on a number of markers of clinical outcomes in the perioperative period, but their current role is also poorly defined. Clinical studies evaluating nutritional interventions have been marred by conflicting data, which may be due to small sample sizes, as well as heterogeneity of patients and surgical procedures. At present, it is known that carbohydrate loading is safe and improves patients’ wellbeing, but does not appear to influence length of hospital stay or rate of postoperative complications. This should be appreciated before its routine inclusion in ERAS programs.
Fasting Or Starving? Measurement of Blood Ketone Levels in 100 Fasted Elective and Emergency Adult Surgical Patients at An Australian Tertiary Hospital
Authors: Burstal R. J. , Reilly J. R. , Burstal B.
Published: January 2019

Prolonged fasting leads to a shift from carbohydrate to fat as the primary energy source, resulting in the production of ketones such as beta-hydroxybutyrate. Hyperketonaemia and ketoacidosis have been observed in young children fasting for surgery. The aim of this study was to investigate ketonaemia in adults fasted for surgery. One hundred non-diabetic adults presenting for elective or emergency surgery were assessed for the presence of hyperketonaemia (beta-hydroxybutyrate levels more than 1 mmol/l), and the relationship between beta-hydroxybutyrate, blood glucose and fasting duration was investigated. Three of 100 patients demonstrated hyperketonaemia, one of whom had ingested a ketogenic supplement the evening prior to surgery. No patient demonstrated beta-hydroxybutyrate levels suggestive of ketoacidosis (above 3 mmol/l). No relationship between fasting duration and ketone or glucose levels was observed. We found no evidence that prolonged preoperative fasting led to beta-hydroxybutyrate levels consistent with ketoacidosis.
A Randomised Controlled Trial Comparing Fibreoptic-Guided Tracheal Intubation through Two Supraglottic Devices: Ambu® Auragain™ Laryngeal Mask and LMA® Fastrach™
Authors: Preece G. , Ng I. , Lee K. , Mezzavia P. , Krieser R. , Williams D. L. , Stewart O. , Segal R.
Published: January 2019

The Ambu®AuraGain™ laryngeal mask (LM) (Ambu A/S, Ballerup, Denmark) is one of the few readily available second-generation supraglottic airway devices (SADs) that offer a conduit for fibreoptic-guided endotracheal intubation. We aimed to compare fibreoptic intubation through this device with the LMA® (laryngeal mask airway) Fastrach™ (Teleflex Medical, Co. Westmeath, Ireland), which has been a recommended dedicated rescue device for the management of the unanticipated difficult airway. This randomised controlled trial compared a previously described fibreoptic score in 116 patients with no known airway pathology, who had asleep fibreoptic endotracheal intubation via either the AuraGain LM or the LMA Fastrach. Time, ease and success rate of SAD and endotracheal tube (ETT) insertion and complications were recorded. The AuraGain LM demonstrated better laryngeal alignment with 29 out of 59 patients in the AuraGain LM (AG) group having a Grade 4 view (only vocal cords visible), compared to 20 out of 54 patients in the LMA Fastrach (FT) group (P=0.003). It allowed significantly quicker and easier ETT intubation when used as a conduit. The AuraGain LM was also quicker to insert compared to the Fastrach LMA. Similar rates of minor complications, such as sore throat and dysphonia occurred in both groups. Our study indicates that when used in patients with complete muscle relaxation and no known airway pathology, the AuraGain LM achieves better laryngeal alignment and quicker, easier and more successful fibreoptic-guided ETT intubation than the Fastrach LMA.
Adhesive Arachnoiditis following Inadvertent Epidural Injection of 2% Chlorhexidine in 70% Alcohol—Partial Recovery over the Ensuing Eight Years
Authors: Iqbal I. Mohamed , Morris R. , Hersch M.
Published: January 2019

We report a case of serious neurologic injury due to inadvertent epidural injection of 8 ml of the antiseptic 2% chlorhexidine in 70% alcohol during a procedure aimed to relieve the pain of labour. This resulted in immediate severe back pain, progressive tetraparesis and sphincter dysfunction caused by damage to the spinal cord and nerve roots. Subacute hydrocephalus necessitated drainage, but cranial nerve and cognitive function were spared. Magnetic resonance imaging documented marked abnormality of the spinal cord and surrounding leptomeninges. In the ensuing eight years, there has been clinical and electrophysiological evidence of partial recovery, but neurologic deficit remains severe.
Vitamin D Status and Supplementation in Adult Patients Receiving Extracorporeal Membrane Oxygenation
Authors: Nair P. , Venkatesh B. , Hoechter D. J. , Buscher H. , Kerr S. , Center J. R. , Myburgh J. A.
Published: January 2019

The prevalence of vitamin D deficiency in critical illness is known to be high and associated with adverse clinical outcomes. Patients receiving extracorporeal membrane oxygenation (ECMO) may be at increased risk of vitamin D deficiency due to high severity of acute illness. Challenges with drug dosing in ECMO patients are recognised due to increased volume of distribution and drug absorption to circuit components. To describe the prevalence of vitamin D deficiency in ECMO patients and the effect of intramuscular dosing of cholecalciferol on levels of vitamin D metabolites, and to compare these data with intensive care unit (ICU) patients not receiving ECMO, two prospective studies were performed sequentially: an observational study of 100 consecutive ICU patients and an interventional study assessing effects of intramuscular cholecalciferol in 50 ICU patients. The subgroup of patients who required ECMO support in each of these studies was analysed and compared to patients who did not receive ECMO. Twenty-four ECMO patients, 12 from the observational study and 12 from the interventional study (who received intramuscular cholecalciferol) were studied—21/24 (88%) ECMO patients were vitamin D deficient at baseline compared to 65/126 (52%) of non-ECMO patients (P=0.006). Of the 12 ECMO patients who received cholecalciferol, six patients (50%) achieved correction of deficiency compared to 36/38 (95%) non-ECMO patients (P=0.001). The prevalence of vitamin D deficiency is higher in ECMO patients compared to other critically ill adults. Correction of deficiency with single dose cholecalciferol is not reliable; higher or repeated doses should be considered to correct deficiency.
Preoperative Gastric Residual Volumes in Fasted Patients Measured by Bedside Ultrasound: A Prospective Observational Study
Authors: Ohashi Y. , Walker J. C. , Zhang F. , Prindiville F. E. , Hanrahan J. P. , Mendelson R. , Corcoran T.
Published: January 2019

The purpose of this prospective observational study was to measure gastric volumes in fasted patients using bedside gastric ultrasound. Patients presenting for non-emergency surgery underwent a gastric antrum assessment, using the two-diameter and free-trace methods to determine antral cross-sectional area. Gastric residual volume (GRV) was calculated using a validated formula. Univariate and multivariable analyses were performed to examine any potential relationships between ‘at risk’ GRVs (>100 ml) and patient factors. Two hundred and twenty-two successful scans were performed; of these 110 patients (49.5%) had an empty stomach, nine patients (4.1%) had a GRV >100 ml, and a further six patients (2.7%) had a GRV >1.5 ml/kg. There was no significant relationship between ‘at risk’ GRV and obesity, diabetes mellitus, gastro-oesophageal reflux disease or opioid use, although our study had insufficient power to exclude an influence of one or more of these factors. Our results indicate that despite compliance with fasting guidelines, a small percentage of patients still have GRVs that pose a pulmonary aspiration risk. Anaesthetists should consider this background incidence when choosing anaesthesia techniques for their patients. While future observational studies are required to determine the role of preoperative bedside gastric ultrasound, it is possible that this technique may assist anaesthetists in identifying patients with ‘at risk’ GRVs.
The Effect of Preload on Electromyographic Train-Of-Four Ratio at the First Dorsal Interosseous Muscle during Spontaneous Recovery from Neuromuscular Blockade
Authors: Bansal A. , Stewart P. A. , Phillips S. , Liang S. , Wang X.
Published: January 2019

Accurate and reliable quantitative neuromuscular function monitoring is desirable for the optimal management of neuromuscular blockade, selection of the most appropriate reversal agent and dosage, and assessing the completeness of reversal to exclude residual neuromuscular blockade. Applying preload to the thumb may affect the precision of electromyography. This study compared the precision and agreement of electromyography with and without preload during recovery from non-depolarising neuromuscular blockade. After induction of anaesthesia and before neuromuscular blockade, the supramaximal current required at the first dorsal interosseous muscle with and without preload was determined. During recovery, train-of-four ratios were recorded using electromyography every 20 seconds. Alternating pairs of measurements (with and without preload) were obtained until spontaneous recovery was achieved. The preload device applied a resting tension of 75–150 g to the thumb. Bland–Altman analysis for repeated measurements was used to assess precision and agreement of electromyography responses with and without muscle preload. Two hundred and seventy-five sets of repeated measurements were collected from 35 participants. The repeatability coefficient for train-of-four ratios recorded by electromyography with a preload was 0.030 (95% confidence intervals, CI, 0.028 to 0.031) versus 0.068 (95% CI 0.064 to 0.072) without. Train-of-four ratios with preload demonstrated a bias of +0.038 (95% CI 0.037 to 0.042) compared to electromyography without, with 95% limits of agreement of 0.035–0.111. Preload significantly improved the precision of electromyographic train-of-four ratios, with 95% of consecutive measurements differing by less than 3%. Furthermore, electromyography with preload demonstrated a positive bias of 0.04 compared with electromyography alone, the clinical significance of which requires further research.
Unusual Partnerships: The Corfe–McMurdie Anaesthetic Inhaler of 1918 and the 2nd Australian Casualty Clearing Station
Authors: Cooper M. G. , Gebels A. C. , Bailey R. J. , Whish D. K. M.
Published: January 2019

This World War 1 ether/chloroform vaporiser-inhaler was designed by and made for Captain Anstruther John Corfe by Private Eric Aspinall McMurdie, both of the 2nd Australian Casualty Clearing Station (ACCS), Australian Army Medical Corps (AAMC). It has a plaque attached labelled 25 May 1918. It is a perfect example of the ingenuity forced by the realities of war, and is one of the unique pieces in the Harry Daly Museum at the Australian Society of Anaesthetists (ASA) headquarters in Sydney, Australia. While serving in Blendecques, France, Private McMurdie ingeniously fashioned this vaporiser from discarded items he found on the battlefield. These included Horlick's Malted Milk bottles, on which he etched measurements for ether and chloroform, and a spent brass artillery shell, which made the heating component of the inhaler. The 2nd ACCS triaged and operated on thousands of troops, and this inhaler is a reflection of the skills and innovative expertise of the staff of the 2nd ACCS which included X-rays to localise foreign bodies, and locally made splints and apparatus to treat trench foot.
Genesis of the College of Intensive Care Medicine of Australia and New Zealand
Authors: Baker A. B.
Published: January 2019

In 2009 the College of Intensive Care Medicine (CICM) of Australia and New Zealand was inaugurated in Melbourne, Australia. This College now regulates the education, training and accreditation for specialist intensivists for Australia and New Zealand. CICM origins started in 1975 with the formation of the Section of Intensive Care of the Faculty of Anaesthetists, Royal Australasian College of Surgeons (RACS), which moved through intermediary stages as the Faculty of Intensive Care, Australian and New Zealand College of Anaesthetists (ANZCA) when that College was formed from the former Faculty of Anaesthetists RACS, and then the Joint Faculty of Intensive Care Medicine (ANZCA and the Royal Australasian College of Physicians [RACP]), until becoming completely independent as CICM in 2010. There was a period of about 40–50 years evolution from the first formations of intensive care units in Australia and New Zealand, and discussions by the personnel staffing those units amongst themselves and with Members of the Board of the Faculty of Anaesthetists RACS, to the formation of the Section of Intensive Care, then through two intermediary Faculties of Intensive Care Medicine, to the final independent formation of the College of Intensive Care Medicine of Australia and New Zealand in 2010.
Feasibility and Acceptability of Metformin to Augment Low Milk Supply: A Pilot Randomized Controlled Trial
Authors: Nommsen-Rivers Laurie , Thompson Amy , Riddle Sarah , Ward Laura , Wagner Erin , King Eileen
Published: January 2019

Background:

Metformin improves insulin action, but feasibility in treating low milk supply is unknown.

Research aim:

To determine the feasibility of a metformin- versus-placebo definitive randomized clinical trial in women with low milk production and signs of insulin resistance.

Methods:

Pilot trial criteria included: Mother 1–8 weeks postpartum (ideally 1–2 weeks), low milk production, and ≥1 insulin resistance sign; and singleton, healthy, term infant. Eligible mothers were randomly assigned 2:1 (metformin:placebo) and instructed in frequent milk removal for 28 days with option to stop at 14 days.

Results:

From 02/2015 through 06/2016, we screened 114 women, completed baseline assessments on 46, and trialed 15 (median, 36 days postpartum). Comparing metformin-assigned ( n = 10) to placebo ( n = 5), 70% versus 80% continued to day 28; peak median change in milk output was +8 versus –58 mL/24 hr ( p = .31) and 80% peaked at Day 14 for both groups; 0% versus 20% desired to continue assigned drug after study completion; 44% versus 0% reported nausea/vomiting. Post-hoc, median peak change in milk output was +22 (metformin completers, n = 8) versus –58 mL/24 hr (placebo + non-completers, n = 7, p = .07). At baseline assessment, median milk production was significantly lower in those with ( n = 31), versus those without ( n = 15) signs of insulin resistance ( p = .002).

Conclusions:

Although results trend toward hypothesized direction, trial feasibility concerns include late enrollment and only 20% of metformin-assigned participants sustaining improved milk output to Day 28, with none perceiving metformin worthwhile. Better tools are needed to identify and treat metabolically-driven low milk production. Registered at ClinicalTrials.gov (NCT02179788) on 02/JUL/2014.
Modeling the hygrothermal creep behavior of wood plastic composite (WPC) lumber made from thermally modified wood
Authors: Alrubaie Murtada Abass A , Lopez-Anido Roberto A , Gardner Douglas J , Tajvidi Mehdi , Han Yousoo
Published: January 2019

The viscoelastic behavior of an extruded wood plastic composite (WPC) made from thermally modified wood under hygrothermal treatment was studied and modeled. Multiple three-point bending creep/recovery tests were carried out using a dynamic mechanical thermal analyzer (DMTA) equipped with a submersible clamp. WPC specimens with a 15-mm span were subjected to two initial applied stresses; 9% and 14% of the flexural strength in 30 min of creep and 30 min of creep recovery under the combined effects of temperature (25°C, 35°C, and 45°C) and water immersion (saltwater (SW) and distilled water). A dry condition WPC control was used to compare the hygrothermal effects with respect to the control conditions. The WPC material in this article exhibited a linear viscoelastic behavior under the effect of temperature, whereas a nonlinear viscoelastic behavior was observed under immersion conditions. A power law model is considered a useful model to describe the creep behavior of WPC specimens with a 15-mm span in the control and the SW conditions and at 45°C. A power law model was used to describe 180-day creep deflection of WPC lumber beams with an 853-mm span subjected to 12 MPa of the flexural strength in four-point bending at 50% relative humidity and at 21°C. The power law model predicts that the WPC lumber will reach a flexural strain in outer fiber of 1% in approximately 150 years.
A HOPE for Study Abroad: Evidence From Tennessee on the Impact of Merit-Aid Policy Adoption on Study Abroad Participation
Authors: Kramer Dennis A. , Wu Jiayao
Published: January 2019

Two distinct literature bases exist documenting the benefits of study aboard participation and state-adopted merit-aid policies. However, few, to date, have estimated the impact of merit-aid adoption on study abroad participation. Results from our study demonstrate the potential positive externality merit-aid policy adoption has on study abroad participation. In addition, we find that increases in study abroad participation is concentrated primarily within public doctoral/research institutions and institutions with students from more affluent families.
Evaluation of thermal stability and damping behavior of electrical insulator waste reinforced thermoset polymer composite
Authors: Sabarinathan P , Annamalai VE , Rajkumar K
Published: January 2019

This paper deals with the influence of inorganic electrical insulator waste filler on the properties of glass fiber reinforced epoxy composite. The electrical insulator waste fillers were uniformly mixed in the resin through ultrasonication technique. Composites were made up with different percentages of filler (0, 5, 10, 20 wt%) and 20 wt% glass fiber using the hand lay-up method. Physical, mechanical, water absorption, thermal, and dynamic mechanical properties were studied. The experimental results indicate an increase in water absorption and density of composites with increased electrical insulator waste filler in the polymer matrix. Furthermore, the filler addition reduces the tensile strength and increases the flexural strength to 402 MPa at 20% addition. The thermogravimetric analysis reveals that the incorporation of electrical insulator waste filler increases the thermal stability considerably. Dynamic property reveals the damping property of the materials, in which the incorporation of 20% filler leads to higher storage modulus. Particle dispersion and failure mode were analyzed using scanning electron microscope. This work highlights the possibility for reprocessing electrical insulator waste as low-cost reinforcement in polymer composites.
Inertia parameter identification of space floating target during robotic exploratory grasping
Authors: Wei Cheng , Zhang Yue , Wang Hongliu , Zhao Yang , Zhang Lei
Published: January 2019

When the space robot grasps an unknown floating target on orbit, it has many advantages of knowing the inertial parameters of the target during the exploratory grasping process, since, instead of grasping blindly the better control schema can be made in the meantime to increase the safety and performance of the grasping operation. The three-finger gripper is used as the grasp mechanism for which the grasping and contact models are presented to describe the grasping procedure. Then based on the momentum conservation of the robot–target system, the linear identification model of the target inertia parameters is developed. The identification performance for one, two, and three collisions during the grasping process is investigated theoretically. It is found that the full inertia parameters will be obtained within at least three collisions between the space robot and the target. Lastly the identification model for an unknown target is applied, and the numerical simulations show the effectiveness and practicality of the model. The numerical results indicate that the identification method is effective. Furthermore, the more abundant and diverse the collisions are, the more accurate and efficient the identification method will be.
Trichomonas vaginalis virus: a review of the literature
Authors: Graves KJ , Ghosh AP , Kissinger PJ , Muzny CA
Published: January 2019

Trichomonas vaginalis (TV) is a parasitic protozoan responsible for the sexually transmitted infection trichomoniasis. Trichomonas vaginalis virus (TVV) is a nonsegmented, 4.5–5 kbp, double-stranded RNA virus, from the Totiviridae family, which inhabits TV. A capsid protein consisting of 120 subunits is covered in channels aiding in RNA release. TVV is closely associated with the Golgi complex and is transmitted vertically. TVV has four subspecies, TVV1, TVV2, TVV3, and TVV4. The clinical significance of TVV and its effect on the pathogenicity of TV is not well known. We performed a systematic review of the literature on TVV to better understand its clinical significance and its role in the pathogenesis of TV.
A methodological exploration for efficient prediction of airfoil response to gusts in wind engineering
Authors: Wu Zhenlong , Wang Qiang , Huang Hao
Published: January 2019

This paper presents several approaches for efficient estimation of airfoil response to gust via computational fluid dynamics and reduced-order modeling. A computational fluid dynamics code enabling simulation of aerodynamics under an arbitrary-shaped discrete gust is adopted. Convolution models using baseline sharp-edge gust response either obtained by the closed-form Küssner functions or computational fluid dynamics methods are established. A parametric approximation function model for gust response is identified via the least square optimization of the computational fluid dynamics-obtained sharp-edge responses. Finally, an example taking advantage of the aerodynamic response by the above methods to simulate the aeroelastics of an airfoil performing a plunging-twisting coupled motion under various gusts is presented. The present practice indicates that the reduced-order modelings are not only more efficient compared to direct computational fluid dynamics simulations, but also have a satisfactory accuracy in gust response predictions.
The influence of Material Nonlinearity and Microstructural Damage on the Inplane Shear response of Carbon/Epoxy Composites
Authors: Gipple K , Camponeschi E T
Published: January 2019

Accurate nonlinear material models must include both material and damage related nonlinearities. Even at the specimen level macromechanical boundary conditions and specimen geometry can significantly affect the measured response. In this study two experimental techniques for determining shear stress strain response are compared and a micromechanical finite element analysis is used to determine the effect of failure theory on predicted nonlinear response.
Creep of [0/90] Scs-6 Fiber-Reinforced Si3N4 composites
Authors: Yang J-M , Chen S T
Published: January 2019

The creep response of a [0/90] cross-ply SCS-6 fiber-reinforced Si3N4 composite has been measured using four-point flexural loading at temperatures between 1200 - 1300 °C and at stresses ranging from 100 - 200 MPa. Parameters characterizing the stress dependence of steady-state creep rates and mechanisms of creep deformation were determined.
Some Issues about the Numerical simulation of Mold Filling in Resin Transfer Molding
Authors: Trochu F , Gauvin R
Published: January 2019

The resin impregnation of the fibrous reinforcement in resin transfer molding (RTM) is usually modeled as a flow through a porous medium (Darcy's law). In our model, Darcy equation is solved numerically at each time step using non-conforming finite elements on a fixed grid.
Transport Characteristics in Moving Resin front of A Mold Flow
Authors: Gong Haiqing
Published: January 2019

The velocity field is analytically obtained for the resin flow with a moving front in a rectangular mold. The results exhibit the characteristics of steady fountain flow. Approximate solutions in form of partial sums and their accuracies are also investigated.
On the Notch-Sensitivity and toughness of A Ceramic Composite
Authors: Kedward Keith T , Beaumont Peter W R
Published: January 2019

A Nicalon TM/SiC fabric (8-harness satin) reinforced alumina matrix (CMC) was loaded in tension to fracture. A coating on the surface of the fibre reduced the strength of the fibre-matrix bond, increased the toughness of the CMC by more than 3 times, and raised the unnotched strength by more than 2 times.
Polymeric Composite Hip-Joint Prosthesis
Authors: Akay M , Aslan N
Published: January 2019

It has been claimed that the durability of hip-joint replacement improves with isoelastic prostheses. A PEEK composite accordingly appears to be a suitable material system. Prosthesis-stems were injection moulded from 30% short CF reinforced PEEK and a preliminary FE analysis indicated improved mechanical compatibility between the bone and the stem.
Damage tolerance of Symmetric Buffer Strip Laminates
Authors: Venkatakrishnaiah S , Dharani L R
Published: January 2019

The feasibility of using buffer strips for improving the notched strength and crack arrest capability with several combinations of main panel and buffer strip materials is investigated. The results show that a proper selection of main panel and buffer strip material ensures crack arrest and improved notch strength.
The Fracture behaviour of Vectran/Epoxy Quasi-Isotropic Laminates
Authors: Maekawa Zen-ichiro , Hamada Hiroyuki , Kitagawa Tomohiro , Okumura Toshihiko
Published: January 2019

Tensile behaviour of quasi-isotropic [0/μ45/90]s liquid crystalline fiber reinforced composites were discussed. The fracture modes were observed by microscope and scanning electron microscope. As the result, initial fracture did not originate in 90° lamina, but in 45° lamina.
Impregnation Behavior and Transverse Bending properties of Thermoplastic Composites Made from Commingled Twisted Spun Yarn
Authors: Matsuo Tatsuki , Ikegawa Naoto
Published: January 2019

Transverse bending tests were carried out for unidirectional composites fabricated from twisted spun yarn commingled of carbon fiber and Nylon 6 fiber by compression molding. Transverse bending strength was explained in conjunction with their impregnation behaviors.
Design of Cruciform Specimens for Biaxial testing of Composites
Authors: Runkle J L D , Doucet A B
Published: January 2019

Orthotropic finite element analysis was used to design a cruciform specimen for use in biaxial testing of fiber reinforced composites. Several notch designs were investigated and the optimal specimen shape was chosen as the one in which failure would more likely occur in the gage section rather than across the cruciform arms.
Effect of fibre off-Axis Misalignment on Composite Strength
Authors: Liu X C
Published: January 2019

Fibre off-axis misalignment in an unidirectional MMC results in initiating cracks at a low stress level. In this case, composite strength is close to ROM value only in a low Vf, and the strength hardly increases with Vf when Vf is superior to a certain value.
Analysis on Thermoplastic Composites Systems
Authors: Matsuo T
Published: January 2019

Many kinds of molding materials and molding methods relating to thermoplastic composites have ever been developed. An attempt to make clear arrangement for these materials and molding methods was carried out. Materials were systematically classified. The relationships among materials, molding methods and molded parts were summarized in a table.
Effects of Stitching on Composite Impact Behaviour and Stiffness
Authors: Lee-Sullivan P , Seng L T
Published: January 2019

The influence of stitching technique on the damage pattern of impacted glass/epoxy composite laminates was investigated. Two different techniques were evaluated; running-stitching (RS) and cross-stitching (CS) respectively. CS was found to be better than RS in suppressing delamination growth. Even so, the RS laminate was less susceptible to delamination than the unstitched equivalent. Although stitching is beneficial, it causes significant reduction in tensile stiffness but has minimal effects on the flexural modulus.
Examining Cfrp Laminate Layup with Contact-Mode Ultrasonic Measurements
Authors: Hsu D K , Margetan F J
Published: January 2019

This letter describes contact-mode ultrasonic measurements for evaluating the layup configuration of cross-plied CFRP laminates, particularly the [0m/90n] l layup. Polarization and velocity of shear waves propagating in the thickness direction were used in deducing the percentages of 0 and 90 degree plies. The angular dependence of an acousto-ultrasonic signal was used in the determination of in-plane fiber directions.
Extension of Classical Laminate Theory to the Anelastic Domain
Authors: Lemoal P. , Perreux D.
Published: January 2019

An extension of classical laminate theory to the anelastic domain is proposed. It is based on numerical methods which describe the laminate's response to mechanical loading not analytically but step by step. This approach is applied to a behaviour model of a non linear viscoelastic layer and its application to multiaxial creep tests on filament wound tubes ± 55°is discussed.
An Energy-Based interpretation of Interfacial Adhesion from Single Fibre Composite Fragmentation Testing
Authors: Wagner H.D. , Ling S.
Published: January 2019

An energy balance approach is proposed for the single fibre composite (or fragmentation) test, by which the degree of fibre-matrix bonding is quantified by means of the interfacial energy, rather than the interfacial shear strength, as a function of the fibre geometrical and mechanical characteristics, the stress transfer length, and the debonding length. The validity of the approach is discussed using E-glass fibres embedded in epoxy, both in the dry state and in the presence of hot distilled water.
Clarifying the application of Weibull Statistics for Determining the Stress state of A Fibre from Fragmentation Tests
Authors: Wagner H. D. , Wood J. R. , Marom G.
Published: January 2019

A novel technique was recently introduced in our laboratories for the measurement of the compressive strength of single fibres, based on a modified configuration of the single fibre composite fragmentation test. In particular, the effect of the length of the embedded fibre on its compressive strength was assessed for the first time, based on Weibull statistics considerations. Moreover, during the sample manufacturing stage, a fibre can break in compression due to induced cooling stresses, rather than mechanical stresses, which can be determined from the fragmentation phenomenon. In this note, improved analyses of such compressive fragmentation effects are presented and discussed.
Analysis of Local Delamination in A Cracked Composite Laminate Loaded in Tension
Authors: Zhang J. , Soutis C.
Published: January 2019

In the present paper the total strain energy release rate G associated with delaminations that initiate from a matrix crack in a [±θm/90n]s composite laminate is calculated using the potential energy approach in elastic fracture mechanics. The predictions are compared with a two-dimensional finite element analysis. It is found that for delamination lengths greater than two-ply thicknesses the theoretical and numerical results are in good agreement. The new model shows that G is affected by the matrix crack density and residual hygrothermal stresses.
Creep behaviour of Hybrid Composites Based on Polyethylene and Carbon Fibres
Authors: Peijs A.A.J.M. , Schellens H.J. , Govaert L.E.
Published: January 2019

This study investigates the effect of hybridization of high-performance polyethylene (HP-PE) fibres reinforced composites with carbon fibres on the creep behaviour of the resulting hybrid composites. Interesting hybrid effects were related to a lowering of the stress level in the HP-PE fibres upon hybridization and creep, eliminating the plastic flow contribution in the HP-PE fibre.
Effect of Argon Plasma Pre-Treatment on adhesion of Epoxy to Aramid Fibers Treated with Oxygen Plasmas
Authors: Knickrehm A. , Rehm W. , Schwartz P.
Published: January 2019

Microbond techniques are used to evaluate the interfacial shear strength ( IFSS) of epoxy on aramid fibers after plasma treatments. Argon gas plasmas are used to prepare the surface of the fibers for treatment using oxygen plasmas. Improvements in IFSS are shown to occur with both argon and oxygen treatment, and with the combination of oxygen and argon.
An Improved Method for the preparation of High Quality Carbon Fibre Composite Test Bars
Authors: Tudgey G F
Published: January 2019

The properties of carbon fibre composites derived from novel matrix polymers are often required for evaluation. An improved method has been developed to enable the preparation of unidirectional carbon fibre composite test bars of uniform high quality using only small quantities of matrix polymer.
The influence of Carbon Fibre Surface Treatment on Fibre-Fibre Interactions in Multi-Fibre Microcomposites
Authors: van den Heuvel P.W.J. , van der Bruggen Y.J.W. , Peijs T.
Published: January 2019

Multi-fibre microcomposites were used to study the influence of fibre/matrix adhesion on the fracture process of composites in uniaxial tension. In addition to in-situ microscopic observations, results were quantitatively described using an interaction criterion. In the case of surface treated carbon fibres, fibre-fibre interaction or so-called coordinated fibre failure takes place at inter-fibre spacings of less than nine fibre diameters. Moreover, it was found that the level of fibre surface treatment, i.e. the amount of debonding, significantly influences the amount of fibre-fibre interaction.
On the Finite Width Correction Factor in Composite Laminates with Elliptical Inclusion
Authors: Xiong Y.
Published: January 2019

A general finite width correction ( FWC) factor is derived in this letter for an anisotropic laminate with elliptical soft/hard inclusion. Using the closed-form solutions for the stress components in the laminate, the derivation of the FWC factor is based on the concept of the global force equilibrium. Some specific cases are discussed. The accuracy of the derived FWC factor is demonstrated.
Platelet Orientation in Slip Cast Ceramic Matrix Composites
Authors: Anderson J. W. , Patel A. , Nettleship I. , Palmiere E.J.
Published: January 2019

Stereological field measurements were used to quantify the orientation of platelets in slip cast composites. The results showed strong orientation of the platelets close to the casting surface. The extent of orientation decreased towards the interior of the specimens. Cylindrical and disk shaped casts showed different trends in platelet orientation.
Measurement of the Interfacial Normal Strength in Single Fibre Transverse Tensile Tests
Authors: Meurs P.F.M. , Schreurs P.J.G. , Peijs T.
Published: January 2019

A technique is presented which can be used to measure the interfacial normal strength in transversely loaded composites. The technique combines the measurement of local deformations during tests in a Scanning Electron Microscope and numerical simulations, in which the measurements are used as boundary conditions. Deformations are measured by placing a grid of markers on the surface of single fibre specimens. The displacements of these markers are measured during loading of the specimen. Numerical simulations show that the radial and tangential interface stresses increase towards the specimen surface, causing the initiation of debonding at the surface. This effect is supported by tests under an optical microscope. The interfacial normal strength is defined to be the maximum radial interface stress just before the initiation of debonding. Based on the presented results, it can be concluded that the presented technique is a promising tool for the measurement of the interfacial normal stress.
Human Rights and the Grammar of Corporate Social Responsibility
Authors: O’Kelly Ciarán
Published: January 2019

This article explores the language of corporate accounts of business and human rights. Using innovative methods drawn from computational corpus linguistics, the article explores discussions of business and human rights in a data set composed of 346 corporate social responsibility reports drawn from firms in extractive industries. The article concludes that human rights are ‘put to work’ in corporate accounts by reconfiguring their meaning to draw them into the ‘familiar frames’ of business accounting narratives.
Contested boundaries: The moralization and politicization of prostitution in German cities
Authors: Grohs Stephan
Published: January 2019

The local regulation of prostitution in Germany is a contested area of urban politics. In this issue area, morality claims intersect with the material interests of home- and landowners and the security demands of ‘ordinary’ citizens. The Prostitution Law of 2001 has liberalized the legal framework: the legislation ‘normalized’ sex work, triggering the re-definition of urban strategies to regulate prostitution. This article analyses the conflict dynamics and the framing of conflicts over regulations in four German cities. It identifies the main actors, coalition-building processes and the framing of conflicts, and links these elements to the resulting policies. With regard to theory, it explores the relevance of classical explanatory approaches to local governance such as party politics, urban growth coalitions, political culture and bureaucratic politics to the value-laden issue of prostitution. It thereby contributes to the growing academic interest in the nature of morality policies and the question of the specific conditions under which prostitution is framed as a moral issue or as a ‘normal’ subject within urban politics.