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Sample records for mechanical chest compressions

  1. Mechanical versus manual chest compressions for out-of-hospital cardiac arrest: a meta-analysis of randomized controlled trials.

    PubMed

    Tang, Lu; Gu, Wan-Jie; Wang, Fei

    2015-01-01

    Recent evidence regarding mechanical chest compressions in out-of-hospital cardiac arrest (OHCA) is conflicting. The objective of this study was to perform a meta-analysis of randomized controlled trials (RCTs) to compare the effect of mechanical versus manual chest compressions on resuscitation outcomes in OHCA. PubMed, Embase, the Cochrane Central Register of Controlled Trials, and the ClinicalTrials.gov registry were searched. In total, five RCTs with 12,510 participants were included. Compared with manual chest compressions, mechanical chest compressions did not significantly improve survival with good neurological outcome to hospital discharge (relative risks (RR) 0.80, 95% CI 0.61-1.04, P = 0.10; I(2) = 65%), return of spontaneous circulation (RR 1.02, 95% CI 0.95-1.09, P = 0.59; I(2) = 0%), or long-term (≥6 months) survival (RR 0.96, 95% CI 0.79-1.16, P = 0.65; I(2) = 16%). In addition, mechanical chest compressions were associated with worse survival to hospital admission (RR 0.94, 95% CI 0.89-1.00, P = 0.04; I(2) = 0%) and to hospital discharge (RR 0.88, 95% CI 0.78-0.99, P = 0.03; I(2) = 0%). Based on the current evidence, widespread use of mechanical devices for chest compressions in OHCA cannot be recommended. PMID:26503429

  2. Mechanical chest compressions in an avalanche victim with cardiac arrest: an option for extreme mountain rescue operations.

    PubMed

    Pietsch, Urs; Lischke, Volker; Pietsch, Christine; Kopp, Karl-Heinz

    2014-06-01

    Mountain rescue operations often present helicopter emergency medical service crews with unique challenges. One of the most challenging problems is the prehospital care of cardiac arrest patients during evacuation and transport. In this paper we outline a case in which we successfully performed a cardiopulmonary resuscitation of an avalanche victim. A mechanical chest-compression device proved to be a good way of minimizing hands-off time and providing high-quality chest compressions while the patient was evacuated from the site of the accident.

  3. Mucus transport mechanisms in relation to the effect of high frequency chest compression (HFCC) on mucus clearance.

    PubMed

    Hansen, L G; Warwick, W J; Hansen, K L

    1994-02-01

    High frequency chest compression (HFCC) appears promising as a form of chest physiotherapy. Studies published by several clinical centers support its efficacy, and further clinical data are expected to become available.

  4. Device Assists Cardiac Chest Compression

    NASA Technical Reports Server (NTRS)

    Eichstadt, Frank T.

    1995-01-01

    Portable device facilitates effective and prolonged cardiac resuscitation by chest compression. Developed originally for use in absence of gravitation, also useful in terrestrial environments and situations (confined spaces, water rescue, medical transport) not conducive to standard manual cardiopulmonary resuscitation (CPR) techniques.

  5. Mechanical Chest Compressions in Prolonged Cardiac Arrest due to ST Elevation Myocardial Infarction Can Cause Myocardial Contusion.

    PubMed

    Stechovsky, Cyril; Hajek, Petr; Cipro, Simon; Veselka, Josef

    2016-09-01

    Acute coronary syndrome is a common cause of sudden cardiac death. We present a case report of a 60-year-old man without a history of coronary artery disease who presented with ST-elevation myocardial infarction. During transportation to the hospital, he developed ventricular fibrillation (VF) and later pulseless electrical activity. Chest compressions with LUCAS 2 (Medtronic, Minneapolis, MN) automated mechanical compression-decompression device were initiated. Coronary angiography showed total occlusion of the left main coronary artery and primary percutaneous coronary intervention (PCI) was performed. After the PCI, his heart started to generate effective contractions and LUCAS could be discontinued. Return of spontaneous circulation was achieved after 90 minutes of cardiac arrest. The patient died of cardiogenic shock 11 hours later. An autopsy revealed a transmural anterolateral myocardial infarction but also massive subepicardial hemorrhage and interstitial edema and hemorrhages on histologic samples from regions of the myocardium outside the infarction itself and also from the right ventricle. These lesions were concluded to be a myocardial contusion. The true incidence of myocardial contusion as a consequence of mechanical chest compressions is not known. We speculate that severe myocardial contusion might have influenced outcome of our patient. PMID:27574387

  6. A simulation tool to study high-frequency chest compression energy transfer mechanisms and waveforms for pulmonary disease applications.

    PubMed

    O'Clock, George D; Lee, Yong Wan; Lee, Jongwon; Warwick, Warren J

    2010-07-01

    High-frequency chest compression (HFCC) can be used as a therapeutic intervention to assist in the transport and clearance of mucus and enhance water secretion for cystic fibrosis patients. An HFCC pump-vest and half chest-lung simulation, with 23 lung generations, has been developed using inertance, compliance, viscous friction relationships, and Newton's second law. The simulation has proven to be useful in studying the effects of parameter variations and nonlinear effects on HFCC system performance and pulmonary system response. The simulation also reveals HFCC waveform structure and intensity changes in various segments of the pulmonary system. The HFCC system simulation results agree with measurements, indicating that the HFCC energy transport mechanism involves a mechanically induced pulsation or vibration waveform with average velocities in the lung that are dependent upon small air displacements over large areas associated with the vest-chest interface. In combination with information from lung physiology, autopsies and a variety of other lung modeling efforts, the results of the simulation can reveal a number of therapeutic implications.

  7. Chest compression with a higher level of pressure support ventilation: effects on secretion removal, hemodynamics, and respiratory mechanics in patients on mechanical ventilation*

    PubMed Central

    Naue, Wagner da Silva; Forgiarini, Luiz Alberto; Dias, Alexandre Simões; Vieira, Silvia Regina Rios

    2014-01-01

    OBJECTIVE: To determine the efficacy of chest compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation, in comparison with that of aspiration alone, in removing secretions, normalizing hemodynamics, and improving respiratory mechanics in patients on mechanical ventilation. METHODS: This was a randomized crossover clinical trial involving patients on mechanical ventilation for more than 48 h in the ICU of the Porto Alegre Hospital de Clínicas, in the city of Porto Alegre, Brazil. Patients were randomized to receive aspiration alone (control group) or compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation (intervention group). We measured hemodynamic parameters, respiratory mechanics parameters, and the amount of secretions collected. RESULTS: We included 34 patients. The mean age was 64.2 ± 14.6 years. In comparison with the control group, the intervention group showed a higher median amount of secretions collected (1.9 g vs. 2.3 g; p = 0.004), a greater increase in mean expiratory tidal volume (16 ± 69 mL vs. 56 ± 69 mL; p = 0.018), and a greater increase in mean dynamic compliance (0.1 ± 4.9 cmH2O vs. 2.8 ± 4.5 cmH2O; p = 0.005). CONCLUSIONS: In this sample, chest compression accompanied by an increase in pressure support significantly increased the amount of secretions removed, the expiratory tidal volume, and dynamic compliance. (ClinicalTrials.gov Identifier:NCT01155648 [http://www.clinicaltrials.gov/]) PMID:24626270

  8. Effect of the rate of chest compression familiarised in previous training on the depth of chest compression during metronome-guided cardiopulmonary resuscitation: a randomised crossover trial

    PubMed Central

    Bae, Jinkun; Chung, Tae Nyoung; Je, Sang Mo

    2016-01-01

    Objectives To assess how the quality of metronome-guided cardiopulmonary resuscitation (CPR) was affected by the chest compression rate familiarised by training before the performance and to determine a possible mechanism for any effect shown. Design Prospective crossover trial of a simulated, one-person, chest-compression-only CPR. Setting Participants were recruited from a medical school and two paramedic schools of South Korea. Participants 42 senior students of a medical school and two paramedic schools were enrolled but five dropped out due to physical restraints. Intervention Senior medical and paramedic students performed 1 min of metronome-guided CPR with chest compressions only at a speed of 120 compressions/min after training for chest compression with three different rates (100, 120 and 140 compressions/min). Friedman's test was used to compare average compression depths based on the different rates used during training. Results Average compression depths were significantly different according to the rate used in training (p<0.001). A post hoc analysis showed that average compression depths were significantly different between trials after training at a speed of 100 compressions/min and those at speeds of 120 and 140 compressions/min (both p<0.001). Conclusions The depth of chest compression during metronome-guided CPR is affected by the relative difference between the rate of metronome guidance and the chest compression rate practised in previous training. PMID:26873050

  9. Comparison of chest compression quality between the modified chest compression method with the use of smartphone application and the standardized traditional chest compression method during CPR.

    PubMed

    Park, Sang-Sub

    2014-01-01

    The purpose of this study is to grasp difference in quality of chest compression accuracy between the modified chest compression method with the use of smartphone application and the standardized traditional chest compression method. Participants were progressed 64 people except 6 absentees among 70 people who agreed to participation with completing the CPR curriculum. In the classification of group in participants, the modified chest compression method was called as smartphone group (33 people). The standardized chest compression method was called as traditional group (31 people). The common equipments in both groups were used Manikin for practice and Manikin for evaluation. In the meantime, the smartphone group for application was utilized Android and iOS Operating System (OS) of 2 smartphone products (G, i). The measurement period was conducted from September 25th to 26th, 2012. Data analysis was used SPSS WIN 12.0 program. As a result of research, the proper compression depth (mm) was shown the proper compression depth (p< 0.01) in traditional group (53.77 mm) compared to smartphone group (48.35 mm). Even the proper chest compression (%) was formed suitably (p< 0.05) in traditional group (73.96%) more than smartphone group (60.51%). As for the awareness of chest compression accuracy, the traditional group (3.83 points) had the higher awareness of chest compression accuracy (p< 0.001) than the smartphone group (2.32 points). In the questionnaire that was additionally carried out 1 question only in smartphone group, the modified chest compression method with the use of smartphone had the high negative reason in rescuer for occurrence of hand back pain (48.5%) and unstable posture (21.2%). PMID:24704648

  10. High-frequency chest compression: a summary of the literature.

    PubMed

    Dosman, Cara F; Jones, Richard L

    2005-01-01

    The purpose of the present literature summary is to describe high-frequency chest compression (HFCC), summarize its history and outline study results on its effect on mucolysis, mucus transport, pulmonary function and quality of life. HFCC is a mechanical method of self-administered chest physiotherapy, which induces rapid air movement in and out of the lungs. This mean oscillated volume is an effective method of mucolysis and mucus clearance. HFCC can increase independence. Some studies have shown that HFCC leads to more mucus clearance and better lung function compared with conventional chest physiotherapy. However, HFCC also decreases end-expiratory lung volume, which can lead to increased airway resistance and a decreased oscillated volume. Adding positive end-expiratory pressure to HFCC has been shown to prevent this decrease in end-expiratory lung volume and to increase the oscillated volume. It is possible that the HFCC-induced decrease in end-expiratory lung volume may result in more mucus clearance in airways that remain open by reducing airway size. Adjunctive methods, such as positive end-expiratory pressure, may not always be needed to make HFCC more effective.

  11. Chest Compression-Only CPR: A Meta-Analysis

    PubMed Central

    Hüpfl, Michael; Selig, Harald F; Nagele, Peter

    2010-01-01

    Summary Background Evidence suggests that dispatcher-assisted chest compression-only bystander CPR may be superior to standard CPR (chest compressions and rescue ventilation) in out-of-hospital cardiac arrest, yet recent clinical trials did not observe improved outcomes. The goal of the study was to determine the association between chest compression-only CPR and survival after out-of-hospital cardiac arrest. Methods Studies published until August 2010 were systematically searched and identified in MEDLINE and EMBASE databases. For the primary meta-analysis only clinical trials were included that prospectively randomized dispatcher instructions to chest compression-only versus standard bystander CPR in out-of-hospital adult cardiac arrest patients; for the secondary meta-analysis observational cohort studies were included that distinguished between standard CPR and chest compression-only CPR. All studies were required to contain survival data. Data on study characteristics, methods and outcomes (return of spontaneous circulation, survival to discharge, 30-day survival, and favourable neurologic outcome) were extracted. A fixed-effects model was used for both meta-analyses for lack of heterogeneity among the studies (I2 0%). Findings All three published randomized clinical trials were included in the meta-analysis. The pooled analyses shows that dispatcher-assisted chest compression-only bystander CPR for adult out-of-hospital cardiac arrest was associated with a 22% improved chance of survival (risk ratio [RR] 1.22 [95% confidence interval {CI}, 1.01 – 1.47]; I2, 0%) compared to standard CPR. The absolute increase in survival was 2.4%; the number needed to treat was 41. The secondary meta-analysis included seven observational studies of bystander-CPR (not dispatcher-assisted) and showed no difference between the two CPR techniques (RR, 0.96 [95% CI, 0.83 – 1.11]; I2, 0%). Interpretation Dispatcher-assisted chest compression-only bystander CPR is associated with

  12. Factors affecting the accuracy of chest compression depth estimation

    PubMed Central

    Kang, Jung Hee; Cha, Won Chul; Chae, Minjung Kathy; Park, Hang A; Hwang, Sung Yeon; Jin, Sang Chan; Lee, Tae Rim; Shin, Tae Gun; Sim, Min Seob; Jo, Ik Joon; Song, Keun Jeong; Rhee, Joong Eui; Jeong, Yeon Kwon

    2014-01-01

    Objective We aimed to estimate the accuracy of visual estimation of chest compression depth and identify potential factors affecting accuracy. Methods This simulation study used a basic life support mannequin, the Ambu man. We recorded chest compression with 7 different depths from 1 to 7 cm. Each video clip was recorded for a cycle of compression. Three different viewpoints were used to record the video. After filming, 25 clips were randomly selected. Health care providers in an emergency department were asked to estimate the depth of compressions while watching the selected video clips. Examiner determinants such as experience and cardiopulmonary resuscitation training and environment determinants such as the location of the camera (examiner) were collected and analyzed. An estimated depth was considered correct if it was consistent with the one recorded. A multivariate analysis predicting the accuracy of compression depth estimation was performed. Results Overall, 103 subjects were enrolled in the study; 42 (40.8%) were physicians, 56 (54.4%) nurses, and 5 (4.8%) emergency medical technicians. The mean accuracy was 0.89 (standard deviation, 0.76). Among examiner determinants, only subjects’ occupation and clinical experience showed significant association with outcome (P=0.03 and P=0.08, respectively). All environmental determinants showed significant association with the outcome (all P<0.001). Multivariate analysis showed that accuracy rate was significantly associated with occupation, camera position, and compression depth. Conclusions The accuracy rate of chest compression depth estimation was 0.89 and was significantly related with examiner’s occupation, camera view position, and compression depth.

  13. High frequency chest compression therapy: a case study.

    PubMed

    Butler, S; O'Neill, B

    1995-01-01

    A new device, the ThAIRapy Bronchial Drainage System, enables patients with cystic fibrosis to self-administer the technique of high frequency chest compression (HFCC) to assist with mucociliary clearance. We review the literature on HFCC and outline a case study of a patient currently using the ThAIRapy Bronchial Drainage System. While mucociliary clearance and lung function may be enhanced by HFCC therapy, more research is needed to determine its efficacy, cost benefits, and optimum treatment guidelines. Although our initial experience with the patient using this device has been positive, we were unable to accurately evaluate the ThAIRapy Bronchial Drainage System.

  14. Analyzing cardiac rhythm in the presence of chest compression artifact for automated shock advisory.

    PubMed

    Babaeizadeh, Saeed; Firoozabadi, Reza; Han, Chengzong; Helfenbein, Eric D

    2014-01-01

    Defibrillation is often required to terminate a ventricular fibrillation or fast ventricular tachycardia rhythm and resume a perfusing rhythm in sudden cardiac arrest patients. Automated external defibrillators rely on automatic ECG analysis algorithms to detect the presence of shockable rhythms before advising the rescuer to deliver a shock. For a reliable rhythm analysis, chest compression must be interrupted to prevent corruption of the ECG waveform due to the artifact induced by the mechanical activity of compressions. However, these hands-off intervals adversely affect the success of treatment. To minimize the hands-off intervals and increase the chance of successful resuscitation, we developed a method which asks for interrupting the compressions only if the underlying ECG rhythm cannot be accurately determined during chest compressions. Using this method only a small percentage of cases need compressions interruption, hence a significant reduction in hands-off time is achieved. Our algorithm comprises a novel filtering technique for the ECG and thoracic impedance waveforms, and an innovative method to combine analysis from both filtered and unfiltered data. Requiring compression interruption for only 14% of cases, our algorithm achieved a sensitivity of 92% and specificity of 99%.

  15. Comparison of expectorated sputum after manual chest physical therapy and high-frequency chest compression.

    PubMed

    Warwick, Warren J; Wielinski, Catherine L; Hansen, Leland G

    2004-01-01

    This study is a quantitative comparison of the sputum produced by 12 subjects with cystic fibrosis (CF) who received high-frequency chest compression (HFCC) and standard chest physical therapy (CPT) in randomized order. Six subjects routinely used manual CPT and six routinely used the HFCC. None had acute infections or hospitalization in the six weeks before the study. Two certified respiratory therapists alternated subjects and CPT vs HFCC order during the two weeks of the matched study. For all sessions, the expectorated sputum was collected in preweighed cups, which were reweighed immediately after collection and again after evaporation to dryness. The wet and dry weights of the sputum produced as a result of the two techniques were significantly different, with HFCC having greater weight. Regardless of the mode of therapy, the sputum produced by the subjects who regularly received HFCC had greater water content than did the sputum produced by those subjects who regularly received CPT. No significant difference was found between the two therapists regarding sputum expectorated by the subjects during CPT. These results show that sputum production by subjects with CF who receive CPT by certified respiratory therapists can be as great as the sputum produced by the same subjects who receive HFCC. The results also suggest that unknown factors attributed to the therapists may produce different levels of effort from time to time that may decrease the respiratory therapists' effectiveness, whereas the HFCC therapy may be more consistently effective because it is entirely machine based.

  16. The comparison of three high-frequency chest compression devices.

    PubMed

    Lee, Yong W; Lee, Jongwon; Warwick, Warren J

    2008-01-01

    High-frequency chest compression (HFCC) is shown to enhance clearance of pulmonary airway secretions. Several HFCC devices have been designed to provide this therapy. Standard equipment consists of an air pulse generator attached by lengths of tubing to an adjustable, inflatable vest/jacket (V/J) garment. In this study, the V/Js were fitted over a mannequin. The three device air pulse generators produced characteristic waveform patterns. The variations in the frequency and pressure setting of devices were consistent with specific device design features. These studies suggest that a better understanding of the effects of different waveform, frequency, and pressure combinations may improve HFCC therapeutic efficacy of three different HFCC machines. The V/J component of HFCC devices delivers the compressive pulses to the chest wall to produce both airflow through and oscillatory effects in the airways. The V/J pressures of three HFCC machines were measured and analyzed to characterize the frequency, pressure, and waveform patterns generated by each of three device models. The dimensions of all V/Js were adjusted to a circumference of approximately 110% of the chest circumference. The V/J pressures were measured, and maximum, minimum, and mean pressure, pulse pressure, and root mean square of three pulse generators were calculated. Jacket pressures ranged between 2 and 34 mmHg. The 103 and 104 models' pulse pressures increased with the increase in HFCC frequency at constant dial pressure. With the ICS the pulse pressure decreased when the frequency increased. The waveforms of models 103 and 104 were symmetric sine wave and asymmetric sine wave patterns, respectively. The ICS had a triangular waveform. At 20 Hz, both the 103 and 104 were symmetric sine waveform but the ICS remained triangular. Maximum crest factors emerged in low-frequency and high-pressure settings for the ICS and in the high-frequency and low-pressure settings for models 103 and 104. Recognizing the

  17. High frequency chest compression effects heart rate variability.

    PubMed

    Lee, Jongwon; Lee, Yong W; Warwick, Warren J

    2007-01-01

    High frequency chest compression (HFCC) supplies a sequence of air pulses through a jacket worn by a patient to remove excessive mucus for the treatment or prevention of lung disease patients. The air pulses produced from the pulse generator propagates over the thorax delivering the vibration and compression energy. A number of studies have demonstrated that the HFCC system increases the ability to clear mucus and improves lung function. Few studies have examined the change in instantaneous heart rate (iHR) and heart rate variability (HRV) during the HFCC therapy. The purpose of this study is to measure the change of HRV with four experimental protocols: (a) without HFCC, (b) during Inflated, (c)HFCC at 6Hz, and (d) HFCC at 21Hz. The nonlinearity and regularity of HRV was assessed by approximate entropy (ApEn), a method used to quantify the complexities and randomness. To compute the ApEn, we sectioned with a total of eight epochs and displayed the ApEn over the each epoch. Our results show significant differences in the both the iHR and HRV between the experimental protocols. The iHR was elevated at both the (c) 6Hz and (d) 21Hz condition from without HFCC (10%, 16%, respectively). We also found that the HFCC system tends to increase the HRV. Our study suggests that monitoring iHR and HRV are very important physiological indexes during HFCC therapy.

  18. Chest Compression With Personal Protective Equipment During Cardiopulmonary Resuscitation

    PubMed Central

    Chen, Jie; Lu, Kai-Zhi; Yi, Bin; Chen, Yan

    2016-01-01

    Abstract Following a chemical, biological, radiation, and nuclear incident, prompt cardiopulmonary resuscitation (CPR) procedure is essential for patients who suffer cardiac arrest. But CPR when wearing personal protection equipment (PPE) before decontamination becomes a challenge for healthcare workers (HCW). Although previous studies have assessed the impact of PPE on airway management, there is little research available regarding the quality of chest compression (CC) when wearing PPE. A present randomized cross-over simulation study was designed to evaluate the effect of PPE on CC performance using mannequins. The study was set in one university medical center in the China. Forty anesthesia residents participated in this randomized cross-over study. Each participant performed 2 min of CC on a manikin with and without PPE, respectively. Participants were randomized into 2 groups that either performed CC with PPE first, followed by a trial without PPE after a 180-min rest, or vice versa. CPR recording technology was used to objectively quantify the quality of CC. Additionally, participants’ physiological parameters and subjective fatigue score values were recorded. With the use of PPE, a significant decrease of the percentage of effective compressions (41.3 ± 17.1% with PPE vs 67.5 ± 15.6% without PPE, P < 0.001) and the percentage of adequate compressions (67.7 ± 18.9% with PPE vs 80.7 ± 15.5% without PPE, P < 0.001) were observed. Furthermore, the increases in heart rate, mean arterial pressure, and subjective fatigue score values were more obvious with the use of PPE (all P < 0.01). We found significant deterioration of CC performance in HCW with the use of a level-C PPE, which may be a disadvantage for enhancing survival of cardiac arrest. PMID:27057878

  19. Addition of a video camera system improves the ease of Airtraq(®) tracheal intubation during chest compression.

    PubMed

    Kohama, Hanako; Komasawa, Nobuyasu; Ueki, Ryusuke; Itani, Motoi; Nishi, Shin-ichi; Kaminoh, Yoshiroh

    2012-04-01

    Recent resuscitation guidelines for cardiopulmonary resuscitation emphasize that rescuers should perform tracheal intubation with minimal interruption of chest compressions. We evaluated the use of video guidance to facilitate tracheal intubation with the Airtraq (ATQ) laryngoscope during chest compression. Eighteen novice physicians in our anesthesia department performed tracheal intubation on a manikin using the ATQ with a video camera system (ATQ-V) or with no video guidance (ATQ-N) during chest compression. All participants were able to intubate the manikin using the ATQ-N without chest compression, but five failed during chest compression (P < 0.05). In contrast, all participants successfully secured the airway with the ATQ-V, with or without chest compression. Concurrent chest compression increased the time required for intubation with the ATQ-N (without chest compression 14.8 ± 4.5 s; with chest compression, 28.2 ± 10.6 s; P < 0.05), but not with the ATQ-V (without chest compression, 15.9 ± 5.8 s; with chest compression, 17.3 ± 5.3 s; P > 0.05). The ATQ video camera system improves the ease of tracheal intubation during chest compressions.

  20. Retinal hemorrhage after cardiopulmonary resuscitation with chest compressions.

    PubMed

    Pham, Hang; Enzenauer, Robert W; Elder, James E; Levin, Alex V

    2013-06-01

    Retinal hemorrhages in children in the absence of risk factors are regarded to be pathognomonic of shaken baby syndrome or other nonaccidental injuries. The physician must decide whether the retinal hemorrhages in children without risk factors are due to abuse or cardiopulmonary resuscitation with chest compression (CPR-CC). The objective of this study was to determine if CPR-CC can lead to retinal hemorrhages in children. Twenty-two patients who received in-hospital CPR-CC between February 15, 1990, and June 15, 1990, were enrolled. Pediatric ophthalmology fellows carried a code beeper and responded to calls for cardiopulmonary arrest situations. At the scene of CPR-CC, an indirect funduscopic examination was conducted for presence of retinal hemorrhages in the posterior pole. Follow-up examinations were performed at 24 and 72 hours. Of the 22 patients, 6 (27%) had retinal hemorrhages at the time of CPR-CC. Of these 6 patients, 5 had risk factors for retinal hemorrhages. The sixth patient had no risk factors and may have represented the only true case of retinal hemorrhages due to CPR-CC. Retinal hemorrhages are uncommon findings after CPR-CC. Retinal hemorrhages that are found after CPR-CC usually occur in the presence of other risk factors for hemorrhage with a mild hemorrhagic retinopathy in the posterior pole.

  1. Comparison of high frequency chest compression and conventional chest physiotherapy in hospitalized patients with cystic fibrosis.

    PubMed

    Arens, R; Gozal, D; Omlin, K J; Vega, J; Boyd, K P; Keens, T G; Woo, M S

    1994-10-01

    Clearance of bronchial secretions is essential in the management of cystic fibrosis (CF) patients admitted for acute pulmonary exacerbation. Conventional physiotherapy (CPT) is labor-intensive, time-consuming, expensive, and may not be available as frequently as desired during hospitalization. High frequency chest compression (HFCC), which uses an inflatable vest linked to an air-pulse delivery system, may offer an attractive alternative. To study this, we prospectively studied 50 CF patients admitted for acute pulmonary exacerbation who were randomly allocated to receive either HFCC or CPT three times a day. On admission, clinical status and pulmonary function tests (PFT) in the HFCC group were not significantly different from those measured in the CPT group. Significant improvements in clinical status and PFT were observed after 7 and 14 d of treatment, and were similar in the two study groups, leading to patient discharge after similar periods of hospitalization. We conclude that HFCC and CPT are equally safe and effective when used during acute pulmonary exacerbations in CF patients. We speculate that HFCC may provide an adequate alternative in management of CF patients in a hospital setting.

  2. [Development and animal tests of a miniaturized electrical chest compression device].

    PubMed

    Wang, Chunchen; Zhang, Lei; Li, Yongqin; Chen, Bihua

    2014-02-01

    This paper introduces the development and animal tests of a miniaturized electrical chest compression device. Based on pulse width modulation technology produced by micro control unit, the device can control the frequency and depth of the compression accurately, as well as perform real-time adjustment. Therefore, it can perform continuous and stable chest compression for long time, which may increase the successful rate of cardiopulmonary resuscitation (CPR). Besides, the device can also produce different types of compression waveforms, including trapezoidal and triangular waveforms. Then, the performance and efficacy of the device was assessed with a rat model of asphyxial cardiac arrest (CA). PMID:24804481

  3. Detection of ROSC in Patients with Cardiac Arrest During Chest Compression Using NIRS: A Pilot Study.

    PubMed

    Yagi, Tsukasa; Nagao, Ken; Kawamorita, Tsuyoshi; Soga, Taketomo; Ishii, Mitsuru; Chiba, Nobutaka; Watanabe, Kazuhiro; Tani, Shigemasa; Yoshino, Atsuo; Hirayama, Atsushi; Sakatani, Kaoru

    2016-01-01

    Return of spontaneous circulation (ROSC) during chest compression is generally detected by arterial pulse palpation and end-tidal CO2 monitoring; however, it is necessary to stop chest compression during pulse palpation, and to perform endotracheal intubation for monitoring end-tidal CO2. In the present study, we evaluated whether near-infrared spectroscopy (NIRS) allows the detection of ROSC during chest compression without interruption. We monitored cerebral blood oxygenation in 19 patients with cardiac arrest using NIRS (NIRO-200NX, Hamamatsu Photonics, Japan). On arrival at the emergency room, the attending physicians immediately assessed whether a patient was eligible for this study after conventional advanced life support (ALS) and employed NIRS to measure cerebral blood oxygenation (CBO) in the bilateral frontal lobe in patients. We found cerebral blood flow waveforms in synchrony with chest compressions in all patients. In addition, we observed abrupt increases of oxy-hemoglobin concentration and tissue oxygen index (TOI), which were associated with ROSC detected by pulse palpation. The present findings indicate that NIRS can be used to assess the quality of chest compression in patients with cardiac arrest as demonstrated by the detection of synchronous waveforms during cardiopulmonary resuscitation (CPR). NIRS appears to be applicable for detection of ROSC without interruption of chest compression and without endotracheal intubation. PMID:26782207

  4. Optimizing chest compressions during delivery-room resuscitation.

    PubMed

    Wyckoff, Myra H; Berg, Robert A

    2008-12-01

    There is a paucity of data to support the recommendations for cardiac compressions for the newly born. Techniques, compression to ventilation ratios, hand placement, and depth of compression guidelines are generally based on expert consensus, physiologic plausibility, and data from pediatric and adult models.

  5. Chest compressions for bradycardia or asystole in neonates.

    PubMed

    Kapadia, Vishal; Wyckoff, Myra H

    2012-12-01

    When effective ventilation fails to establish a heart rate of greater than 60 bpm, cardiac compressions should be initiated to improve perfusion. The 2-thumb method is the most effective and least fatiguing technique. A ratio of 3 compressions to 1 breath is recommended to provide adequate ventilation, the most common cause of newborn cardiovascular collapse. Interruptions in compressions should be limited to not diminishing the perfusion generated. Oxygen (100%) is recommended during compressions and can be reduced once adequate heart rate and oxygen saturation are achieved. Limited clinical data are available to form newborn cardiac compression recommendations.

  6. Influence of Chest Compressions on Circulation during the Peri-Cardiac Arrest Period in Porcine Models

    PubMed Central

    Li, Yan; Walline, Joseph; Zheng, Liangliang; Fu, Yangyang; Yao, Dongqi; Zhu, Huadong; Liu, Xiaohe; Chai, Yanfen; Wang, Zhong; Yu, Xuezhong

    2016-01-01

    Objective Starting chest compressions immediately after a defibrillation shock might be harmful, if the victim already had a return of spontaneous circulation (ROSC) and yet was still being subjected to external compressions at the same time. The objective of this study was to study the influence of chest compressions on circulation during the peri-cardiac arrest period. Design Prospective, randomized controlled study. Setting Animal experimental center in Peking Union Medical Collage Hospital, Beijing, China. Subjects Healthy 3-month-old male domestic pigs. Interventions 44 pigs (28±2 kg) were randomly assigned to three groups: Group I (non-arrested with compressions) (n = 12); Group II (arrested with compressions only) (n = 12); Group III (ROSC after compressions and defibrillation) (n = 20). In Groups I and II, compressions were performed to a depth of 5cm (Ia and IIa, n = 6) or a depth of 3cm (Ib and IIb, n = 6) respectively, while in Group III, the animals which had just achieved ROSC (n = 18) were compressed to a depth of 5cm (IIIa, n = 6), a depth of 3cm (IIIb, n = 6), or had no compressions (IIIc, n = 6). Hemodynamic parameters were collected and analyzed. Measurements and Findings Hemodynamics were statistically different between Groups Ia and Ib when different depths of compressions were performed (p < 0.05). In Group II, compressions were beneficial and hemodynamics correlated with the depth of compressions (p < 0.05). In Group III, compressions that continued after ROSC produced a reduction in arterial pressure (p < 0.05). Conclusions Chest compressions might be detrimental to hemodynamics in the early post-ROSC stage. The deeper the compressions were, the better the effect on hemodynamics during cardiac arrest, but the worse the effect on hemodynamics after ROSC. PMID:27168071

  7. Chest wall mechanics in sustained microgravity

    NASA Technical Reports Server (NTRS)

    Wantier, M.; Estenne, M.; Verbanck, S.; Prisk, G. K.; Paiva, M.; West, J. B. (Principal Investigator)

    1998-01-01

    We assessed the effects of sustained weightlessness on chest wall mechanics in five astronauts who were studied before, during, and after the 10-day Spacelab D-2 mission (n = 3) and the 180-day Euromir-95 mission (n = 2). We measured flow and pressure at the mouth and rib cage and abdominal volumes during resting breathing and during a relaxation maneuver from midinspiratory capacity to functional residual capacity. Microgravity produced marked and consistent changes (Delta) in the contribution of the abdomen to tidal volume [DeltaVab/(DeltaVab + DeltaVrc), where Vab is abdominal volume and Vrc is rib cage volume], which increased from 30.7 +/- 3. 5 (SE)% at 1 G head-to-foot acceleration to 58.3 +/- 5.7% at 0 G head-to-foot acceleration (P < 0.005). Values of DeltaVab/(DeltaVab + DeltaVrc) did not change significantly during the 180 days of the Euromir mission, but in the two subjects DeltaVab/(DeltaVab + DeltaVrc) was greater on postflight day 1 than on subsequent postflight days or preflight. In the two subjects who produced satisfactory relaxation maneuvers, the slope of the Konno-Mead plot decreased in microgravity; this decrease was entirely accounted for by an increase in abdominal compliance because rib cage compliance did not change. These alterations are similar to those previously reported during short periods of weightlessness inside aircrafts flying parabolic trajectories. They are also qualitatively similar to those observed on going from upright to supine posture; however, in contrast to microgravity, such postural change reduces rib cage compliance.

  8. Estimation of optimal pediatric chest compression depth by using computed tomography

    PubMed Central

    Jin, Soo Young; Oh, Seong Beom; Kim, Young Oh

    2016-01-01

    Objective This study aimed to compare the optimal chest compression depth for infants and children with that of adults when the simulated compression depth was delivered according to the current guidelines. Methods A total of 467 consecutive chest computed tomography scans (93 infants, 110 children, and 264 adults) were reviewed. The anteroposterior diameter and compressible diameter (CD) for infants and children were measured at the inter-nipple level and at the mid-lower half of the spine for adults. Compression ratio (CR) to CD was calculated at simulated 1/4, 1/3, and 1/2 antero-posterior compressions in infants and children, and simulated 5- and 6-cm compressions in adults. Results In adults, the CRs to CD at simulated 5- and 6-cm compression depth were 41.7±0.16%, 50.0±7.3% respectively. In children and infants, the CRs to CD at 1/3 chest compression were 55.1±2.4% and 51.8±2.4%, respectively, and at 1/2 chest compression, CRs were 82.7±3.7% and 77.7±3.6%, respectively. The CRs to CD of 4-cm compression depth in infants and 5-cm compression depth in children were 74.4±10.9%, 62.5±8.7%, respectively. The CRs to CD for children and infants were significantly higher than in adults (P<0.001). The CR to CD of 4-cm compression depth in children was almost similar to that of 6-cm compression depth in adults (50.0± 6.9% vs. 50.0±7.3%, P=0.985). Conclusion Current pediatric guidelines for compression depth are too deep compared to those in adults. We suggest using 1/3 of the anteroposterior chest diameter or about 4 cm in children and less than 4 cm in infants. PMID:27752612

  9. A simple accurate chest-compression depth gauge using magnetic coils during cardiopulmonary resuscitation

    NASA Astrophysics Data System (ADS)

    Kandori, Akihiko; Sano, Yuko; Zhang, Yuhua; Tsuji, Toshio

    2015-12-01

    This paper describes a new method for calculating chest compression depth and a simple chest-compression gauge for validating the accuracy of the method. The chest-compression gauge has two plates incorporating two magnetic coils, a spring, and an accelerometer. The coils are located at both ends of the spring, and the accelerometer is set on the bottom plate. Waveforms obtained using the magnetic coils (hereafter, "magnetic waveforms"), which are proportional to compression-force waveforms and the acceleration waveforms were measured at the same time. The weight factor expressing the relationship between the second derivatives of the magnetic waveforms and the measured acceleration waveforms was calculated. An estimated-compression-displacement (depth) waveform was obtained by multiplying the weight factor and the magnetic waveforms. Displacements of two large springs (with similar spring constants) within a thorax and displacements of a cardiopulmonary resuscitation training manikin were measured using the gauge to validate the accuracy of the calculated waveform. A laser-displacement detection system was used to compare the real displacement waveform and the estimated waveform. Intraclass correlation coefficients (ICCs) between the real displacement using the laser system and the estimated displacement waveforms were calculated. The estimated displacement error of the compression depth was within 2 mm (<1 standard deviation). All ICCs (two springs and a manikin) were above 0.85 (0.99 in the case of one of the springs). The developed simple chest-compression gauge, based on a new calculation method, provides an accurate compression depth (estimation error < 2 mm).

  10. A simple accurate chest-compression depth gauge using magnetic coils during cardiopulmonary resuscitation.

    PubMed

    Kandori, Akihiko; Sano, Yuko; Zhang, Yuhua; Tsuji, Toshio

    2015-12-01

    This paper describes a new method for calculating chest compression depth and a simple chest-compression gauge for validating the accuracy of the method. The chest-compression gauge has two plates incorporating two magnetic coils, a spring, and an accelerometer. The coils are located at both ends of the spring, and the accelerometer is set on the bottom plate. Waveforms obtained using the magnetic coils (hereafter, "magnetic waveforms"), which are proportional to compression-force waveforms and the acceleration waveforms were measured at the same time. The weight factor expressing the relationship between the second derivatives of the magnetic waveforms and the measured acceleration waveforms was calculated. An estimated-compression-displacement (depth) waveform was obtained by multiplying the weight factor and the magnetic waveforms. Displacements of two large springs (with similar spring constants) within a thorax and displacements of a cardiopulmonary resuscitation training manikin were measured using the gauge to validate the accuracy of the calculated waveform. A laser-displacement detection system was used to compare the real displacement waveform and the estimated waveform. Intraclass correlation coefficients (ICCs) between the real displacement using the laser system and the estimated displacement waveforms were calculated. The estimated displacement error of the compression depth was within 2 mm (<1 standard deviation). All ICCs (two springs and a manikin) were above 0.85 (0.99 in the case of one of the springs). The developed simple chest-compression gauge, based on a new calculation method, provides an accurate compression depth (estimation error < 2 mm).

  11. Detail view of steam chest and valve mechanisms for high ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of steam chest and valve mechanisms for high pressure stage of unit 40. - Burnsville Natural Gas Pumping Station, Saratoga Avenue between Little Kanawha River & C&O Railroad line, Burnsville, Braxton County, WV

  12. Clinical utility of wavelet compression for resolution-enhanced chest radiography

    NASA Astrophysics Data System (ADS)

    Andriole, Katherine P.; Hovanes, Michael E.; Rowberg, Alan H.

    2000-05-01

    This study evaluates the usefulness of wavelet compression for resolution-enhanced storage phosphor chest radiographs in the detection of subtle interstitial disease, pneumothorax and other abnormalities. A wavelet compression technique, MrSIDTM (LizardTech, Inc., Seattle, WA), is implemented which compresses the images from their original 2,000 by 2,000 (2K) matrix size, and then decompresses the image data for display at optimal resolution by matching the spatial frequency characteristics of image objects using a 4,000- square matrix. The 2K-matrix computed radiography (CR) chest images are magnified to a 4K-matrix using wavelet series expansion. The magnified images are compared with the original uncompressed 2K radiographs and with two-times magnification of the original images. Preliminary results show radiologist preference for MrSIDTM wavelet-based magnification over magnification of original data, and suggest that the compressed/decompressed images may provide an enhancement to the original. Data collection for clinical trials of 100 chest radiographs including subtle interstitial abnormalities and/or subtle pneumothoraces and normal cases, are in progress. Three experienced thoracic radiologists will view images side-by- side on calibrated softcopy workstations under controlled viewing conditions, and rank order preference tests will be performed. This technique combines image compression with image enhancement, and suggests that compressed/decompressed images can actually improve the originals.

  13. A Comparison of Chest Compression Quality Delivered During On-Scene and Ground Transport Cardiopulmonary Resuscitation

    PubMed Central

    Russi, Christopher S.; Myers, Lucas A.; Kolb, Logan J.; Lohse, Christine M.; Hess, Erik P.; White, Roger D.

    2016-01-01

    Introduction American Heart Association (AHA) guidelines recommend cardiopulmonary resuscitation (CPR) chest compressions 1.5 to 2 inches (3.75–5 cm) deep at 100 to 120 per minute. Recent studies demonstrated that manual CPR by emergency medical services (EMS) personnel is substandard. We hypothesized that transport CPR quality is significantly worse than on-scene CPR quality. Methods We analyzed adult patients receiving on-scene and transport chest compressions from nine EMS sites across Minnesota and Wisconsin from May 2008 to July 2010. Two periods were analyzed: before and after visual feedback. CPR data were collected and exported with the Zoll M series monitor and a sternally placed accelerometer measuring chest compression rate and depth. We compared compression data with 2010 AHA guidelines and Zoll RescueNet Code Review software. CPR depth and rate were “above (deep),” “in,” or “below (shallow)” the target range according to AHA guidelines. We paired on-scene and transport data for each patient; paired proportions were compared with the nonparametric Wilcoxon signed rank test. Results In the pre-feedback period, we analyzed 105 of 140 paired cases (75.0%); in the post-feedback period, 35 of 140 paired cases (25.0%) were analyzed. The proportion of correct depths during on-scene compressions (median, 41.9%; interquartile range [IQR], 16.1–73.1) was higher compared to the paired transport proportion (median, 8.7%; IQR, 2.7–48.9). Proportions of on-scene median correct rates and transport median correct depths did not improve in the post-feedback period. Conclusion Transport chest compressions are significantly worse than on-scene compressions. Implementation of visual real-time feedback did not affect performance. PMID:27625733

  14. A Comparison of Chest Compression Quality Delivered During On-Scene and Ground Transport Cardiopulmonary Resuscitation

    PubMed Central

    Russi, Christopher S.; Myers, Lucas A.; Kolb, Logan J.; Lohse, Christine M.; Hess, Erik P.; White, Roger D.

    2016-01-01

    Introduction American Heart Association (AHA) guidelines recommend cardiopulmonary resuscitation (CPR) chest compressions 1.5 to 2 inches (3.75–5 cm) deep at 100 to 120 per minute. Recent studies demonstrated that manual CPR by emergency medical services (EMS) personnel is substandard. We hypothesized that transport CPR quality is significantly worse than on-scene CPR quality. Methods We analyzed adult patients receiving on-scene and transport chest compressions from nine EMS sites across Minnesota and Wisconsin from May 2008 to July 2010. Two periods were analyzed: before and after visual feedback. CPR data were collected and exported with the Zoll M series monitor and a sternally placed accelerometer measuring chest compression rate and depth. We compared compression data with 2010 AHA guidelines and Zoll RescueNet Code Review software. CPR depth and rate were “above (deep),” “in,” or “below (shallow)” the target range according to AHA guidelines. We paired on-scene and transport data for each patient; paired proportions were compared with the nonparametric Wilcoxon signed rank test. Results In the pre-feedback period, we analyzed 105 of 140 paired cases (75.0%); in the post-feedback period, 35 of 140 paired cases (25.0%) were analyzed. The proportion of correct depths during on-scene compressions (median, 41.9%; interquartile range [IQR], 16.1–73.1) was higher compared to the paired transport proportion (median, 8.7%; IQR, 2.7–48.9). Proportions of on-scene median correct rates and transport median correct depths did not improve in the post-feedback period. Conclusion Transport chest compressions are significantly worse than on-scene compressions. Implementation of visual real-time feedback did not affect performance.

  15. Chest Compression Fraction Determines Survival in Patients with Out-of-hospital Ventricular Fibrillation

    PubMed Central

    Christenson, Jim; Andrusiek, Douglas; Everson-Stewart, Siobhan; Kudenchuk, Peter; Hostler, David; Powell, Judy; Callaway, Clifton W.; Bishop, Dan; Vaillancourt, Christian; Davis, Dan; Aufderheide, Tom P.; Idris, Ahamed; Stouffer, John A.; Stiell, Ian; Berg, Robert

    2009-01-01

    Background Quality CPR contributes to cardiac arrest survival. The proportion of time in which chest compressions are performed in each minute of CPR is an important modifiable aspect of quality CPR. We sought to estimate the effect of an increasing proportion of time spent performing chest compressions during cardiac arrest on survival to hospital discharge in patients with out-of hospital ventricular fibrillation or pulseless ventricular tachycardia. Methods and Results This is a prospective observational cohort study of adult patients from the Resuscitation Outcomes Consortium Cardiac Arrest Epistry with confirmed ventricular fibrillation or ventricular tachycardia, no defibrillation prior to emergency medical services arrival, electronically recorded cardiopulmonary resuscitation prior to the first shock and a confirmed outcome. Patients were followed to discharge from hospital or death. In the 506 cases, the mean age was 64 years, 80% were male, 71% were witnessed by a bystander, 51% received bystander cardiopulmonary resuscitation, 34% occurred in a public location, and 23% survived. After adjustment for age, gender, location, bystander cardiopulmonary resuscitation, bystander witness status, and response time the odds ratios of surviving to hospital discharge in the two highest categories of chest compression fraction compared to the reference category were 3.01 (95% CI, 1.37, 6.58) and 2.33 (95% CI, 0.96, 5.63). The estimated adjusted linear effect on odds ratio of survival for a 10% change in chest compression fraction was 1.11 (95% CI, 1.01, 1.21). Conclusion Increased chest compression fraction is independently predictive of better survival in patients suffering a prehospital ventricular fibrillation/tachycardia cardiac arrest. PMID:19752324

  16. High-frequency chest compression: effect of the third generation compression waveform.

    PubMed

    Milla, Carlos E; Hansen, Leland G; Weber, Adam; Warwick, Warren J

    2004-01-01

    High-frequency chest compression (HFCC) therapy has become the prevailing form of airway clearance for patients with cystic fibrosis (CF) in the United States. The original square waveform was replaced in 1995 with a sine waveform without published evidence of an equality of effectiveness. The recent development of a triangle waveform for HFCC provided the opportunity to compare the functional and therapeutic effects of different waveforms. Clinical testing was done in patients at home with therapy times recorded with all sputum collected in preweighed sealable vials. The eight study patients with CF were regular users of a sine waveform device. They produced sputum consistently and were clinically stable. They used their optimum frequencies for therapy for each waveform and, for one week for each waveform, collected all sputum during their twice-daily timed HFCC therapies. After collection, these vials were reweighed, desiccated, and reweighed to calculate wet and dry weights of sputum per minute of therapy time. Frequency associated vest pressures transmitted to the mouth, and induced airflows at the mouth were measured in healthy volunteers. The pressure waveforms produced in the vest were, in shape, faithfully demonstrable at the mouth. In the healthy subject the transmission occurred in 2 ms and was attenuated to about 75% of the vest pressure for the triangle waveform and 60% for the sine waveform. All patients produced more sputum with the triangle waveform than with the sine waveform. The mean increase was 20%+ range of 4% to 41%. P value was <.001. Future studies of HFCC should investigate the other effects of the sine and triangle waveforms, as well as the neglected square waveform, on mucus clearance and determine the best frequencies for each waveform, disease, and patient.

  17. Effect of block size on image quality for compressed chest radiographs

    NASA Astrophysics Data System (ADS)

    Chen, Ji; Flynn, Michael J.

    1992-05-01

    Data compression can improve imaging system efficiency by reducing the required storage space and the image transmission time. Transform compression methods have been applied to digital radiographs with good results. Block transform compression is usually based on 8 X 8 or 16 X 16 transform blocks for the sake of simplicity and speed. Compression with these small sizes tends to require accurate coefficient representations to prevent blocking artifacts. Weighted quantization of block transform coefficients can reduce the blocking effects and improve compression performance. Full frame compression has the advantage of eliminating blocking effects but the disadvantage of heavy demand for computing resources. Small block compression can retain local variation better and has a simpler and faster implementation. We have evaluated the performance tradeoffs for different block sizes and their effects on the image quality of chest radiographs. The results showed that there is no significant difference in root-mean-square error nor in power spectra between different block sizes for visually lossless compression (at about 10:1 compression ratio).

  18. Compression of digital chest radiographs with a mixture of principal components neural network: evaluation of performance.

    PubMed

    Dony, R D; Coblentz, C L; Nabmias, C; Haykin, S

    1996-11-01

    The performance of a new, neural network-based image compression method was evaluated on digital radiographs for use in an educational environment. The network uses a mixture of principal components (MPC) representation to effect optimally adaptive transform coding of an image and has significant computational advantages over other techniques. Nine representative digital chest radiographs were compressed 10:1, 20:1, 30:1, and 40:1 with the MPC method. The five versions of each image, including the original, were shown simultaneously, in random order, to each of seven radiologists, who rated each one on a five-point scale for image quality and visibility of pathologic conditions. One radiologist also ranked four versions of each of the nine images in terms of the severity of distortion: The four versions represented 30:1 and 40:1 compression with the MPC method and with the classic Karhunen-Loève transform (KLT). Only for the images compressed 40:1 with the MPC method were there any unacceptable ratings. Nevertheless, the images compressed 40:1 received a top score in 26%-33% of the evaluations. Images compressed with the MPC method were rated better than or as good as images compressed with the KLT technique 17 of 18 times. Four of nine times, images compressed 40:1 with the MPC method were rated as good as or better than images compressed 30:1 with the KLT technique.

  19. Ventilation distribution and chest wall mechanics in microgravity

    NASA Technical Reports Server (NTRS)

    Paiva, M.; Wantier, M.; Verbanck, S.; Engel, L. A.; Prisk, G. K.; Guy, H. J. B.; West, J. B.

    1997-01-01

    The effect of gravity on lung ventilation distribution and the mechanisms of the chest wall were investigated. The following tests were performed with the respiratory monitoring system of the Anthorack, flown onboard Spacelab D2 mission: single breath washout (SBW), multiple breath washout (MBW) and argon rebreathing (ARB). In order to study chest wall mechanisms in microgravity, a respiratory inductive plethysmograph was used. The SBW tests did not reach statistical significance, while the ARB tests showed that gravity independent inhomogeneity of specific ventilation is larger than gravity dependent inhomogeneity. In which concerns the chest wall mechanisms, the analysis on the four astronauts during the normal respirations of the relaxation maneuver showed a 40 percent increase on the abdominal contribution to respiration.

  20. Is It Possible to Maintain Consciousness and Spontaneous Ventilation with Chest Compression in the Early Phase of Cardiac Arrest?

    PubMed Central

    Oksar, Menekse; Turhanoglu, Selim

    2016-01-01

    Chest compression is important in cardiopulmonary resuscitation. However, life support algorithms do not specify when chest compression should be initiated in patients with persistent spontaneous normal breathing in the early phase after cardiac arrest. Here we describe the case of a 69-year-old man who underwent femoral bypass surgery and was extubated at the end of the procedure. After extubation, the patient's breathing pattern and respiratory rate were normal. The patient subsequently developed ventricular fibrillation, evident on two monitors. Because defibrillation was ineffective, chest compression was initiated even though the patient had spontaneous normal breathing and defensive motor reflexes, which were continued throughout resuscitation. He regained consciousness and underwent tracheal extubation without neurological sequelae on postoperative day 1. This case highlights the necessity of chest compression in the early phase of cardiac arrest. PMID:26981288

  1. Observer performance assessment of JPEG-compressed high-resolution chest images

    NASA Astrophysics Data System (ADS)

    Good, Walter F.; Maitz, Glenn S.; King, Jill L.; Gennari, Rose C.; Gur, David

    1999-05-01

    The JPEG compression algorithm was tested on a set of 529 chest radiographs that had been digitized at a spatial resolution of 100 micrometer and contrast sensitivity of 12 bits. Images were compressed using five fixed 'psychovisual' quantization tables which produced average compression ratios in the range 15:1 to 61:1, and were then printed onto film. Six experienced radiologists read all cases from the laser printed film, in each of the five compressed modes as well as in the non-compressed mode. For comparison purposes, observers also read the same cases with reduced pixel resolutions of 200 micrometer and 400 micrometer. The specific task involved detecting masses, pneumothoraces, interstitial disease, alveolar infiltrates and rib fractures. Over the range of compression ratios tested, for images digitized at 100 micrometer, we were unable to demonstrate any statistically significant decrease (p greater than 0.05) in observer performance as measured by ROC techniques. However, the observers' subjective assessments of image quality did decrease significantly as image resolution was reduced and suggested a decreasing, but nonsignificant, trend as the compression ratio was increased. The seeming discrepancy between our failure to detect a reduction in observer performance, and other published studies, is likely due to: (1) the higher resolution at which we digitized our images; (2) the higher signal-to-noise ratio of our digitized films versus typical CR images; and (3) our particular choice of an optimized quantization scheme.

  2. A New Chest Compression Depth Feedback Algorithm for High-Quality CPR Based on Smartphone

    PubMed Central

    Song, Yeongtak; Oh, Jaehoon

    2015-01-01

    Abstract Background Although many smartphone application (app) programs provide education and guidance for basic life support, they do not commonly provide feedback on the chest compression depth (CCD) and rate. The validation of its accuracy has not been reported to date. This study was a feasibility assessment of use of the smartphone as a CCD feedback device. In this study, we proposed the concept of a new real-time CCD estimation algorithm using a smartphone and evaluated the accuracy of the algorithm. Materials and Methods Using the double integration of the acceleration signal, which was obtained from the accelerometer in the smartphone, we estimated the CCD in real time. Based on its periodicity, we removed the bias error from the accelerometer. To evaluate this instrument's accuracy, we used a potentiometer as the reference depth measurement. The evaluation experiments included three levels of CCD (insufficient, adequate, and excessive) and four types of grasping orientations with various compression directions. We used the difference between the reference measurement and the estimated depth as the error. The error was calculated for each compression. Results When chest compressions were performed with adequate depth for the patient who was lying on a flat floor, the mean (standard deviation) of the errors was 1.43 (1.00) mm. When the patient was lying on an oblique floor, the mean (standard deviation) of the errors was 3.13 (1.88) mm. Conclusions The error of the CCD estimation was tolerable for the algorithm to be used in the smartphone-based CCD feedback app to compress more than 51 mm, which is the 2010 American Heart Association guideline. PMID:25402865

  3. Retention of basic life support knowledge, self-efficacy and chest compression performance in Thai undergraduate nursing students.

    PubMed

    Partiprajak, Suphamas; Thongpo, Pichaya

    2016-01-01

    This study explored the retention of basic life support knowledge, self-efficacy, and chest compression performance among Thai nursing students at a university in Thailand. A one-group, pre-test and post-test design time series was used. Participants were 30 nursing students undertaking basic life support training as a care provider. Repeated measure analysis of variance was used to test the retention of knowledge and self-efficacy between pre-test, immediate post-test, and re-test after 3 months. A Wilcoxon signed-rank test was used to compare the difference in chest compression performance two times. Basic life support knowledge was measured using the Basic Life Support Standard Test for Cognitive Knowledge. Self-efficacy was measured using the Basic Life Support Self-Efficacy Questionnaire. Chest compression performance was evaluated using a data printout from Resusci Anne and Laerdal skillmeter within two cycles. The training had an immediate significant effect on the knowledge, self-efficacy, and skill of chest compression; however, the knowledge and self-efficacy significantly declined after post-training for 3 months. Chest compression performance after training for 3 months was positively retaining compared to the first post-test but was not significant. Therefore, a retraining program to maintain knowledge and self-efficacy for a longer period of time should be established after post-training for 3 months.

  4. New pre-arrival instructions can avoid abdominal hand placement for chest compressions

    PubMed Central

    2013-01-01

    Objective To investigate if modified pre-arrival instructions using patient’s arm and nipple line as landmarks could avoid abdominal hand placements for chest compressions. Method Volunteers were randomized to one of two telephone instructions: “Kneel down beside the chest. Place one hand in the centre of the victim’s chest and the other on top” (control) or “Lay the patient’s arm which is closest to you, straight out from the body. Kneel down by the patient and place one knee on each side of the arm. Find the midpoint between the nipples and place your hands on top of each other” (intervention). Hand placement was conducted on an adult male and documented by laser measurements. Hand placement, quantified as the centre of the compressing hands in the mid-sagittal plane, was compared to the inter-nipple line (INL) for reference and classified as above or below. Fisher’s exact test was used for comparison of proportions. Results Thirty-six lay people, age range 16–60, were included. None in the intervention group placed their hands in the abdominal region, compared to 5/18 in the control group (p = 0.045). Using INL as a reference, the new instructions resulted in less caudal hand placement, and the difference in mean hand position was 47 mm [95% CI 21,73], p = 0.001. Conclusion New pre-arrival instructions where the patient’s arm and nipple line were used as landmarks resulted in less caudal hand placements and none in the abdominal region. PMID:23799963

  5. Four-stage teaching technique and chest compression performance of medical students compared to conventional technique

    PubMed Central

    Jenko, Matej; Frangež, Maja; Manohin, Aleksander

    2012-01-01

    Aim To compare the 2-stage and 4-stage basic life support teaching technique. The second aim was to test if students’ self-evaluated knowledge was in accordance with their actual knowledge. Methods A total of 126 first-year students of the Faculty of Medicine in Ljubljana were involved in this parallel study conducted in the academic year 2009/2010. They were divided into ten groups. Five groups were taught the 2-stage model and five the 4-stage model. The students were tested in a scenario immediately after the course. Questionnaires were filled in before and after the course. We assessed the absolute values of the chest compression variables and the proportions of students whose performance was evaluated as correct according to our criteria. The results were analyzed with independent samples t test or Mann-Whitney-U test. Proportions were compared with χ2 test. The correlation was calculated with the Pearson coefficient. Results There was no difference between the 2-stage (2S) and the 4-stage approach (4S) in the compression rate (126 ± 13 min-1 vs 124 ± 16 min -1, P = 0.180, independent samples t test), compression depth (43 ± 7 mm vs 44 ± 8 mm, P = 0.368, independent samples t test), and the number of compressions with correct hand placement (79 ± 32% vs 78 ± 12, P = 0.765, Mann-Whitney U-test). However, students from the 4-stage group had a significantly higher average number of compressions per minute (70 ± 13 min -1 2S, 78 ± 12 min-1 4S, P = 0.02, independent samples t test). The percentage of students with all the variables correct was the same (13% 2S, 15% 4S, P = 0.741, χ2 test). There was no correlation between the students’ actual and self-evaluated knowledge (P = 0.158, Pearson coefficient = 0.127). Conclusions The 4-stage teaching technique does not significantly improve the quality of chest compressions. The students’ self-evaluation of their performance after the course was

  6. Minute ventilation at different compression to ventilation ratios, different ventilation rates, and continuous chest compressions with asynchronous ventilation in a newborn manikin

    PubMed Central

    2012-01-01

    Background In newborn resuscitation the recommended rate of chest compressions should be 90 per minute and 30 ventilations should be delivered each minute, aiming at achieving a total of 120 events per minute. However, this recommendation is based on physiological plausibility and consensus rather than scientific evidence. With focus on minute ventilation (Mv), we aimed to compare today’s standard to alternative chest compression to ventilation (C:V) ratios and different ventilation rates, as well as to continuous chest compressions with asynchronous ventilation. Methods Two investigators performed cardiopulmonary resuscitation on a newborn manikin with a T-piece resuscitator and manual chest compressions. The C:V ratios 3:1, 9:3 and 15:2, as well as continuous chest compressions with asynchronous ventilation (120 compressions and 40 ventilations per minute) were performed in a randomised fashion in series of 10 × 2 minutes. In addition, ventilation only was performed at three different rates (40, 60 and 120 ventilations per minute, respectively). A respiratory function monitor measured inspiration time, tidal volume and ventilation rate. Mv was calculated for the different interventions and the Mann–Whitney test was used for comparisons between groups. Results Median Mv per kg in ml (interquartile range) was significantly lower at the C:V ratios of 9:3 (140 (134–144)) and 15:2 (77 (74–83)) as compared to 3:1 (191(183–199)). With ventilation only, there was a correlation between ventilation rate and Mv despite a negative correlation between ventilation rate and tidal volumes. Continuous chest compressions with asynchronous ventilation gave higher Mv as compared to coordinated compressions and ventilations at a C:V ratio of 3:1. Conclusions In this study, higher C:V ratios than 3:1 compromised ventilation dynamics in a newborn manikin. However, higher ventilation rates, as well as continuous chest compressions with asynchronous ventilation gave higher Mv

  7. Evaluation of Chest Injury Mechanisms in Nearside Oblique Frontal Impacts

    PubMed Central

    Iraeus, Johan; Lindquist, Mats; Wistrand, Sofie; Sibgård, Elin; Pipkorn, Bengt

    2013-01-01

    Despite the use of seat belts and modern safety systems, many automobile occupants are still seriously injured or killed in car crashes. Common configurations in these crashes are oblique and small overlap frontal impacts that often lead to chest injuries. To evaluate the injury mechanism in these oblique impacts, an investigation was carried out using mathematical human body model simulations. A model of a simplified vehicle interior was developed and validated by means of mechanical sled tests with the Hybrid III dummy. The interior model was then combined with the human body model THUMS and validated by means of mechanical PMHS sled tests. Occupant kinematics as well as rib fracture patterns were predicted with reasonable accuracy. The final model was updated to conform to modern cars and a simulation matrix was run. In this matrix the boundary conditions, ΔV and PDOF, were varied and rib fracture risk as a function of the boundary conditions was evaluated using a statistical framework. In oblique frontal impacts, two injury producing mechanisms were found; (i) diagonal belt load and (ii) side structure impact. The second injury mechanism was found for PDOFs of 25°–35°, depending on ΔV. This means that for larger PDOFs, less ΔV is needed to cause a serious chest injury. PMID:24406957

  8. Evaluation of chest injury mechanisms in nearside oblique frontal impacts.

    PubMed

    Iraeus, Johan; Lindquist, Mats; Wistrand, Sofie; Sibgård, Elin; Pipkorn, Bengt

    2013-01-01

    Despite the use of seat belts and modern safety systems, many automobile occupants are still seriously injured or killed in car crashes. Common configurations in these crashes are oblique and small overlap frontal impacts that often lead to chest injuries.To evaluate the injury mechanism in these oblique impacts, an investigation was carried out using mathematical human body model simulations. A model of a simplified vehicle interior was developed and validated by means of mechanical sled tests with the Hybrid III dummy. The interior model was then combined with the human body model THUMS and validated by means of mechanical PMHS sled tests. Occupant kinematics as well as rib fracture patterns were predicted with reasonable accuracy.The final model was updated to conform to modern cars and a simulation matrix was run. In this matrix the boundary conditions, ΔV and PDOF, were varied and rib fracture risk as a function of the boundary conditions was evaluated using a statistical framework.In oblique frontal impacts, two injury producing mechanisms were found; (i) diagonal belt load and (ii) side structure impact. The second injury mechanism was found for PDOFs of 25°-35°, depending on ΔV. This means that for larger PDOFs, less ΔV is needed to cause a serious chest injury. PMID:24406957

  9. Evaluation of chest injury mechanisms in nearside oblique frontal impacts.

    PubMed

    Iraeus, Johan; Lindquist, Mats; Wistrand, Sofie; Sibgård, Elin; Pipkorn, Bengt

    2013-01-01

    Despite the use of seat belts and modern safety systems, many automobile occupants are still seriously injured or killed in car crashes. Common configurations in these crashes are oblique and small overlap frontal impacts that often lead to chest injuries.To evaluate the injury mechanism in these oblique impacts, an investigation was carried out using mathematical human body model simulations. A model of a simplified vehicle interior was developed and validated by means of mechanical sled tests with the Hybrid III dummy. The interior model was then combined with the human body model THUMS and validated by means of mechanical PMHS sled tests. Occupant kinematics as well as rib fracture patterns were predicted with reasonable accuracy.The final model was updated to conform to modern cars and a simulation matrix was run. In this matrix the boundary conditions, ΔV and PDOF, were varied and rib fracture risk as a function of the boundary conditions was evaluated using a statistical framework.In oblique frontal impacts, two injury producing mechanisms were found; (i) diagonal belt load and (ii) side structure impact. The second injury mechanism was found for PDOFs of 25°-35°, depending on ΔV. This means that for larger PDOFs, less ΔV is needed to cause a serious chest injury.

  10. Short-Term Effects of High-Frequency Chest Compression and Positive Expiratory Pressure in Patients With Cystic Fibrosis

    PubMed Central

    Fainardi, Valentina; Longo, Francesco; Faverzani, Silvia; Tripodi, Maria Candida; Chetta, Alfredo; Pisi, Giovanna

    2011-01-01

    Background Cystic fibrosis patients require daily airway clearance therapies. The primary objective of this study was to compare the short-term efficacy of high-frequency chest compression and positive expiratory pressure mask on expectorated sputum, pulmonary function, and oxygen saturation in patients with CF hospitalized for an acute pulmonary exacerbation. Methods A controlled randomized cross-over trial with 24 hours between treatments was used. Thirty-four CF patients (26 ± 6.5 years) were included in the study. Before and 30 minutes after each treatment were recorded: pulmonary function testing, oxygen saturation, and perceived dyspnea. Preference for the two devices was assessed. Results No statistically significant difference between high-frequency chest compression and positive expiratory pressure mask was found in sputum production and in lung function testing. A reduction in SpO2 was found after positive expiratory pressure mask (98 ± 1.0% versus 97 ± 1.2%; P < 0.001). Both treatments induced a statistically significant increase in Borg scale for dyspnea without differences between them. Patients reported greater satisfaction with positive expiratory pressure mask than with high-frequency chest compression (P < 0.001). Conclusion High-frequency chest compression and positive expiratory pressure mask have comparable short-term effects on expectorated sputum and lung function. Although positive expiratory pressure mask was associated with a lower SpO2, it was better tolerated than high-frequency chest compression. Keywords Airway clearance therapies; High-frequency chest compression; Sputum; Cystic fibrosis PMID:22393338

  11. Comparison of Methods for the Determination of Cardiopulmonary Resuscitation Chest Compression Fraction

    PubMed Central

    Iyanaga, Masayuki; Gray, Randal; Stephens, Shannon W.; Akinsanya, Olajide; Rodgers, Joel; Smyrski, Kathleen; Wang, Henry E.

    2012-01-01

    Objective While cardiopulmonary resuscitation (CPR) chest compression fraction (CCF) is associated with out-of-hospital cardiac arrest (OHCA) outcomes, there is no standard method for the determination of CCF. We compared nine methods for calculating CCF. Methods We studied consecutive adult OHCA patients treated by Alabama Emergency Medical Services (EMS) agencies of the Resuscitation Outcomes Consortium (ROC) during Jan. 1, 2010 - Oct. 28, 2010. Paramedics used portable cardiac monitors with real-time chest compression detection technology (LifePak 12, Physio-Control, Redmond, Washington). We performed both automated CCF calculation for the entire care episode as well as manual review of CPR data in 1-minute epochs, defining CCF as the proportion of each treatment interval with active chest compressions. We compared the CCF values resulting from 9 calculation methods: 1) mean CCF for the entire patient care episode (automated calculation by manufacturer software), 2) mean CCF for first 3 minutes of patient care, 3) mean CCF for first 5 minutes, 4) mean CCF for first 10 minutes, 5) mean CCF for the entire episode except first 5 minutes, 6) mean CCF for last 5 minutes, 7) mean CCF from start to first shock, 8) mean CCF for the first half of resuscitation, 9) mean CCF for the second half of resuscitation. We compared CCF for Methods 2-9 with Method 1 using paired t-tests with a Bonferroni-adjusted p-value of 0.006 (99.5% confidence intervals). Results Among 102 adult OHCA, patient demographics were: mean age 60.3 years (SD 20.8 years), African American 56.9%, male 63.7%, and shockable ECG rhythm 23.5%. Mean CPR duration was 728 seconds (95% CI: 647-809 seconds). Mean CCF for the 9 CCF calculation methods were: 1) 0.587; 2) 0.526; 3) 0.541; 4) 0.566; 5) 0.562; 6) 0.597; 7) 0.530; 8) 0.550; 9) 0.590%. Compared with Method 1, Method 7 CCF (start to first shock) was slightly lower (−0.057; 99.5% CI: −0.100 – (−0.014)). There were no other statistically

  12. Chest compression quality, exercise intensity, and energy expenditure during cardiopulmonary resuscitation using compression-to-ventilation ratios of 15:1 or 30:2 or chest compression only: a randomized, crossover manikin study

    PubMed Central

    Kwak, Se-Jung; Kim, Young-Min; Baek, Hee Jin; Kim, Se Hong; Yim, Hyeon Woo

    2016-01-01

    Objective Our aim was to compare the compression quality, exercise intensity, and energy expenditure in 5-minute single-rescuer cardiopulmonary resuscitation (CPR) using 15:1 or 30:2 compression-to-ventilation (C:V) ratios or chest compression only (CCO). Methods This was a randomized, crossover manikin study. Medical students were randomized to perform either type of CPR and do the others with intervals of at least 1 day. We measured compression quality, ratings of perceived exertion (RPE) score, heart rate, maximal oxygen uptake, and energy expenditure during CPR. Results Forty-seven students were recruited. Mean compression rates did not differ between the 3 groups. However, the mean percentage of adequate compressions in the CCO group was significantly lower than that of the 15:1 or 30:2 group (31.2±30.3% vs. 55.1±37.5% vs. 54.0±36.9%, respectively; P<0.001) and the difference occurred within the first minute. The RPE score in each minute and heart rate change in the CCO group was significantly higher than those of the C:V ratio groups. There was no significant difference in maximal oxygen uptake between the 3 groups. Energy expenditure in the CCO group was relatively lower than that of the 2 C:V ratio groups. Conclusion CPR using a 15:1 C:V ratio may provide a compression quality and exercise intensity comparable to those obtained using a 30:2 C:V ratio. An earlier decrease in compression quality and increase in RPE and heart rate could be produced by CCO CPR compared with 15:1 or 30:2 C:V ratios with relatively lower oxygen uptake and energy expenditure. PMID:27752633

  13. High-frequency chest compression system to aid in clearance of mucus from the lung.

    PubMed

    Hansen, L G; Warwick, W J

    1990-01-01

    The authors developed a high-frequency chest compression (HFCC) device to aid in mucous clearance for patients with obstructive lung disease. The device, designed for self-therapy, consists of a large-volume variable-frequency air-pulse delivery system and a nonstretchable inflatable vest worn by the patient. Pressure pulses are controlled by the patient and applied during expiration. Pulse frequency is tunable from 5 to 25 Hz. Maximum vest pressure is 39 mmHg (5.2 kPa), with patient-controlled vest inflation and deflation time constants of 0.5 s. Vest pressure increases from 28 mmHg (3.7 kPa) at 5 Hz to 39 mmHg (5.2 kPa) at 25 Hz. Preliminary clinical trials have shown the HFCC device to be more effective than standard chest physical therapy. The HFCC device yielded a mean volume of cleared mucus of 3.3 cc per session, compared with 1.8 cc for a conventional therapy session.

  14. Induced respiratory system modeling by high frequency chest compression using lumped system identification method.

    PubMed

    Lee, Jongwon; Lee, Yong Wan; O'Clock, George; Zhu, Xiaoming; Parhi, Keshab K; Warwick, Warren J

    2009-01-01

    High frequency chest compression (HFCC) treatment systems are used to promote mucus transport and mitigate pulmonary system clearance problems to remove sputum from the airways in patients with Cystic Fibrosis (CF) and at risk of developing chronic obstructive pulmonary disease (COPD). Every HFCC system consists of a pump generator, one or two hoses connected to a vest, to deliver the pulsation. There are three different waveforms in use; symmetric sine, the asymmetric sine and the trapezoid waveforms. There have been few studies that compared the efficacy of a sine waveform with the HFCC pulsations. In this study we present a model of the respiratory system for a young normal subject who is one of co-authors. The input signal is the pressure applied by the vest to chest, at a frequency of 6Hz. Using the system model simulation, the effectiveness of different source waveforms is evaluated and compared by observing the waveform response associated with air flow at the mouth. Also the study demonstrated that the ideal rectangle wave produced the maximum peak air flow, and followed by the trapezoid, triangle and sine waveform. The study suggests that a pulmonary system evaluation or modeling effort for CF patient might be useful as a method to optimize frequency and waveform structure choices for HFCC therapeutic intervention.

  15. Two models of high frequency chest compression therapy: interaction of jacket pressure and mouth airflow.

    PubMed

    Lee, Yong Wan; Lee, Jongwon; Warwick, Warren J

    2007-01-01

    High frequency chest compression (HFCC) therapy assists clearing the secretions in the lung. This paper presents two mathematical models: 1) HFCC jacket function model (JFM) and 2) respiratory function model (RFM). JFM predicts the variation of the jacket pressure (Pj) from the respiratory pattern of mouth airflow (Fm). RFM predicts the HFCC induced mouth airflow (Fm) from the HFCC pulse pressures at the jacket (Pj). Fm and Pj were measured from a healthy subject during HFCC therapy. JFM, which was implemented with 2nd order system using prediction error method, shows the existence of breathing pattern at Pj. RFM, which was implemented with amplitude modulation technique, shows how the HFCC pulses affects to the Fm. JFM calculations match 78% of the measured respiratory pattern of Pj>. RFM calculations match 90% of measured HFCC induced Fm. These models can be used to test new breathing patterns before designing studies on patients having chronic obstructive pulmonary diseases.

  16. Eccentric crank variable compression ratio mechanism

    DOEpatents

    Lawrence, Keith Edward; Moser, William Elliott; Roozenboom, Stephan Donald; Knox, Kevin Jay

    2008-05-13

    A variable compression ratio mechanism for an internal combustion engine that has an engine block and a crankshaft is disclosed. The variable compression ratio mechanism has a plurality of eccentric disks configured to support the crankshaft. Each of the plurality of eccentric disks has at least one cylindrical portion annularly surrounded by the engine block. The variable compression ratio mechanism also has at least one actuator configured to rotate the plurality of eccentric disks.

  17. Chest Compression With Personal Protective Equipment During Cardiopulmonary Resuscitation: A Randomized Crossover Simulation Study.

    PubMed

    Chen, Jie; Lu, Kai-Zhi; Yi, Bin; Chen, Yan

    2016-04-01

    Following a chemical, biological, radiation, and nuclear incident, prompt cardiopulmonary resuscitation (CPR) procedure is essential for patients who suffer cardiac arrest. But CPR when wearing personal protection equipment (PPE) before decontamination becomes a challenge for healthcare workers (HCW). Although previous studies have assessed the impact of PPE on airway management, there is little research available regarding the quality of chest compression (CC) when wearing PPE.A present randomized cross-over simulation study was designed to evaluate the effect of PPE on CC performance using mannequins.The study was set in one university medical center in the China.Forty anesthesia residents participated in this randomized cross-over study.Each participant performed 2 min of CC on a manikin with and without PPE, respectively. Participants were randomized into 2 groups that either performed CC with PPE first, followed by a trial without PPE after a 180-min rest, or vice versa.CPR recording technology was used to objectively quantify the quality of CC. Additionally, participants' physiological parameters and subjective fatigue score values were recorded.With the use of PPE, a significant decrease of the percentage of effective compressions (41.3 ± 17.1% with PPE vs 67.5 ± 15.6% without PPE, P < 0.001) and the percentage of adequate compressions (67.7 ± 18.9% with PPE vs 80.7 ± 15.5% without PPE, P < 0.001) were observed. Furthermore, the increases in heart rate, mean arterial pressure, and subjective fatigue score values were more obvious with the use of PPE (all P < 0.01).We found significant deterioration of CC performance in HCW with the use of a level-C PPE, which may be a disadvantage for enhancing survival of cardiac arrest. PMID:27057878

  18. Three cases of suprachoroidal hemorrhage associated with chest compression or asphyxiation and detected using postmortem computed tomography.

    PubMed

    Oshima, Toru; Yoshikawa, Hiroshi; Ohtani, Maki; Mimasaka, Sohtaro

    2015-05-01

    We report 3 cases of suprachoroidal hemorrhage (SCH) found to be triggered by increased intrathoracic pressure and detected using postmortem computed tomography (PMCT). Case 1 was a man aged in his 50s who was found dead at a landslide site. The autopsy showed clogging of the upper respiratory tract with soil debris from the landslide. The cause of death was determined to be asphyxia. PMCT showed SCH in both eyes, which was believed to be caused by chest compression or choking on the soil debris from the landslide. Case 2 was a woman aged in her 60s who was found dead in the sea. The autopsy revealed injuries primarily to her chest. We concluded that the cause of death was drowning. PMCT showed SCH in her right eye that was believed to be caused by chest compression. Case 3 was a woman aged in her 80s who was buried in a snowdrift and potentially died from hypothermia. PMCT showed SCH in both eyes, which was considered to be from an increase in intrathoracic pressure that might have been caused by the burial in the snow. Histological findings showed serous retinal detachment associated with retinal pigment epithelium damage due to SCH, which indicated that she was alive for several hours after the onset of SCH. The increase in intrathoracic pressure caused by dyspnea or chest compression was considered responsible for the onset of SCH in all of the present cases. PMCT might assist with the differential diagnosis of traumatic asphyxiation by SCH. PMID:25533924

  19. Effects of chest wall compression on expiratory flow rates in patients with chronic obstructive pulmonary disease

    PubMed Central

    Nozoe, Masafumi; Mase, Kyoshi; Ogino, Tomoyuki; Murakami, Shigefumi; Takashima, Sachie; Domen, Kazuhisa

    2016-01-01

    Background: Manual chest wall compression (CWC) during expiration is a technique for removing airway secretions in patients with respiratory disorders. However, there have been no reports about the physiological effects of CWC in patients with chronic obstructive pulmonary disease (COPD). Objective: To compare the effects of CWC on expiratory flow rates in patients with COPD and asymptomatic controls. Method: Fourteen subjects were recruited from among patients with COPD who were receiving pulmonary rehabilitation at the University Hospital (COPD group). Fourteen age-matched healthy subjects were also consecutively recruited from the local community (Healthy control group). Airflow and lung volume changes were measured continuously with the subjects lying in supine position during 1 minute of quiet breathing (QB) and during 1 minute of CWC by a physical therapist. Results: During CWC, both the COPD group and the healthy control group showed significantly higher peak expiratory flow rates (PEFRs) than during QB (mean difference for COPD group 0.14 L/sec, 95% confidence interval (CI) 0.04 to 0.24, p<0.01, mean difference for healthy control group 0.39 L/sec, 95% CI 0.25 to 0.57, p<0.01). In the between-group comparisons, PEFR was significantly higher in the healthy control group than in the COPD group (-0.25 L/sec, 95% CI -0.43 to -0.07, p<0.01). However, the expiratory flow rates at the lung volume at the PEFR during QB and at 50% and 25% of tidal volume during QB increased in the healthy control group (mean difference for healthy control group 0.31 L/sec, 95% CI 0.15 to 0.47, p<0.01: 0.31 L/sec, 95% CI 0.15 to 0.47, p<0.01: 0.27 L/sec, 95% CI 0.13 to 0.41, p<0.01, respectively) but not in the COPD group (0.05 L/sec, 95% CI -0.01 to 0.12: -0.01 L/sec, 95% CI -0.11 to 0.08: 0.02 L/sec, 95% CI -0.05 to 0.90) with the application of CWC. Conclusion: The effects of chest wall compression on expiratory flow rates was different between COPD patients and asymptomatic

  20. Using an inertial navigation algorithm and accelerometer to monitor chest compression depth during cardiopulmonary resuscitation.

    PubMed

    Boussen, Salah; Ibouanga-Kipoutou, Harold; Fournier, Nathalie; Raboutet, Yves Godio; Llari, Maxime; Bruder, Nicolas; Arnoux, Pierre Jean; Behr, Michel

    2016-09-01

    We present an original method using a low cost accelerometer and a Kalman-filter based algorithm to monitor cardiopulmonary resuscitation chest compressions (CC) depth. A three-axis accelerometer connected to a computer was used during CC. A Kalman filter was used to retrieve speed and position from acceleration data. We first tested the algorithm for its accuracy and stability on surrogate data. The device was implemented for CC performed on a manikin. Different accelerometer locations were tested. We used a classical inertial navigation algorithm to reconstruct CPR depth and frequency. The device was found accurate enough to monitor CPR depth and its stability was checked for half an hour without any drift. Average error on displacement was ±0.5mm. We showed that depth measurement was dependent on the device location on the patient or the rescuer. The accuracy and stability of this small low-cost accelerometer coupled to a Kalman-filter based algorithm to reconstruct CC depth and frequency, was found well adapted and could be easily implemented. PMID:27246666

  1. Hyperinvasive approach to out-of hospital cardiac arrest using mechanical chest compression device, prehospital intraarrest cooling, extracorporeal life support and early invasive assessment compared to standard of care. A randomized parallel groups comparative study proposal. “Prague OHCA study”

    PubMed Central

    2012-01-01

    Background Out of hospital cardiac arrest (OHCA) has a poor outcome. Recent non-randomized studies of ECLS (extracorporeal life support) in OHCA suggested further prospective multicenter studies to define population that would benefit from ECLS. We aim to perform a prospective randomized study comparing prehospital intraarrest hypothermia combined with mechanical chest compression device, intrahospital ECLS and early invasive investigation and treatment in all patients with OHCA of presumed cardiac origin compared to a standard of care. Methods This paper describes methodology and design of the proposed trial. Patients with witnessed OHCA without ROSC (return of spontaneous circulation) after a minimum of 5 minutes of ACLS (advanced cardiac life support) by emergency medical service (EMS) team and after performance of all initial procedures (defibrillation, airway management, intravenous access establishment) will be randomized to standard vs. hyperinvasive arm. In hyperinvasive arm, mechanical compression device together with intranasal evaporative cooling will be instituted and patients will be transferred directly to cardiac center under ongoing CPR (cardiopulmonary resuscitation). After admission, ECLS inclusion/exclusion criteria will be evaluated and if achieved, veno-arterial ECLS will be started. Invasive investigation and standard post resuscitation care will follow. Patients in standard arm will be managed on scene. When ROSC achieved, they will be transferred to cardiac center and further treated as per recent guidelines. Primary outcome 6 months survival with good neurological outcome (Cerebral Performance Category 1–2). Secondary outcomes will include 30 day neurological and cardiac recovery. Discussion Authors introduce and offer a protocol of a proposed randomized study comparing a combined “hyperinvasive approach” to a standard of care in refractory OHCA. The protocol is opened for sharing by other cardiac centers with available ECLS and

  2. The long-term effect of high-frequency chest compression therapy on pulmonary complications of cystic fibrosis.

    PubMed

    Warwick, W J; Hansen, L G

    1991-01-01

    A high-frequency chest compression (HFCC) device for clearance of mucous secretions from airways was tested in 16 cystic fibrosis (CF) patients with significant improvement in pulmonary function for the HFCC period, which averaged 22 months per patient. The device consists of a variable air pulse delivery system and a non-stretch inflatable vest worn by the patient to cover the entire torso. The patients perform 30 minute therapy sessions divided into 5 minute periods at each of six frequencies. Individual patient therapy time per day ranged from 30 to 240 minutes. Frequencies used by each patient were determined by measuring air flow at the mouth and calculated volume expired per chest compression during tidal breathing while receiving HFCC at frequencies between 5 and 22 Hz at 1 Hz increments. The frequencies that produced the three highest flows and the three largest volumes were selected for each patient's therapy. Ninety-four percent of patients' regression line slopes for percent predicted forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) became more positive during self-administered HFCC therapy as compared to slopes before HFCC therapy, when manual chest physical therapy was used. Two-sided t-test showed that the mean slopes were more positive for FVC and FEV1 during HFCC therapy than for the manual chest physical therapy period before HFCC therapy. The significance level for both FVC and FEV1 was at P less than 0.001.

  3. Peyton's 4-Steps-Approach in comparison: Medium-term effects on learning external chest compression – a pilot study

    PubMed Central

    Münster, Tobias; Stosch, Christoph; Hindrichs, Nina; Franklin, Jeremy; Matthes, Jan

    2016-01-01

    Introduction: The external chest compression is a very important skill required to maintain a minimum of circulation during cardiac arrest until further medical procedures can be taken. Peyton’s 4-Steps-Approach is one method of skill training, the four steps being: Demonstration, Deconstruction, Comprehension and Execution. Based on CPR skill training, this method is widely, allegedly predominantly used, although there are insufficient studies on Peyton’s 4-Steps-Approach for skill training in CPR in comparison with other methods of skill training. In our study, we compared the medium- term effects on learning external chest compression with a CPR training device in three different groups: PEY (Peyton’s 4-Steps-Approach), PMOD (Peyton’s 4-Steps-Approach without Step 3) and STDM, the standard model, according to the widely spread method “see one, do one” (this is equal to Peyton’s step 1 and 3). Material and Methods: This prospective and randomised pilot study took place during the summer semester of 2009 at the SkillsLab and Simulation Centre of the University of Cologne (Kölner interprofessionelles Skills Lab und Simulationszentrum - KISS). The subjects were medical students (2nd and 3rd semester). They volunteered for the study and were randomised in three parallel groups, each receiving one of the teaching methods mentioned above. One week and 5/6 months after the intervention, an objective, structured single assessment was taken. Compression rate, compression depth, correct compressions, and the sum of correct checklist items were recorded. Additionally, we compared cumulative percentages between the groups based on the correct implementation of the resuscitation guidelines during that time. Results: The examined sample consisted of 134 subjects (68% female; age 22±4; PEY: n=62; PMOD: n=31; STDM: n=41). There was no difference between the groups concerning age, gender, pre-existing experience in CPR or time of last CPR course. The only

  4. Instructions to “push as hard as you can” improve average chest compression depth in dispatcher-assisted Cardiopulmonary Resuscitation

    PubMed Central

    Mirza, Muzna; Brown, Todd B.; Saini, Devashish; Pepper, Tracy L; Nandigam, Hari Krishna; Kaza, Niroop; Cofield, Stacey S.

    2008-01-01

    Background and Objective Cardiopulmonary Resuscitation (CPR) with adequate chest compression depth appears to improve first shock success in cardiac arrest. We evaluate the effect of simplification of chest compression instructions on compression depth in dispatcher-assisted CPR protocol. Methods Data from two randomized, double-blinded, controlled trials with identical methodology were combined to obtain 332 records for this analysis. Subjects were randomized to either modified Medical Priority Dispatch System (MPDS) v11.2 protocol or a new simplified protocol. The main difference between the protocols was the instruction to “push as hard as you can” in the simplified protocol, compared to “push down firmly 2 inches (5cm)” in MPDS. Data were recorded via a Laerdal® ResusciAnne® SkillReporter™ manikin. Primary outcome measures included: chest compression depth, proportion of compressions without error, with adequate depth and with total release. Results Instructions to “push as hard as you can”, compared to “push down firmly 2 inches (5cm)”, resulted in improved chest compression depth (36.4 vs 29.7 mm, p<0.0001), and improved median proportion of chest compressions done to the correct depth (32% vs <1%, p<0.0001). No significant difference in median proportion of compressions with total release (100% for both) and average compression rate (99.7 vs 97.5 per min, p<0.56) was found. Conclusions Modifying dispatcher-assisted CPR instructions by changing “push down firmly 2 inches (5cm)” to “push as hard as you can” achieved improvement in chest compression depth at no cost to total release or average chest compression rate. PMID:18635306

  5. Investigation of non-uniform airflow signal oscillation during high frequency chest compression

    PubMed Central

    Sohn, Kiwon; Warwick, Warren J; Lee, Yong W; Lee, Jongwon; Holte, James E

    2005-01-01

    Background High frequency chest compression (HFCC) is a useful and popular therapy for clearing bronchial airways of excessive or thicker mucus. Our observation of respiratory airflow of a subject during use of HFCC showed the airflow oscillation by HFCC was strongly influenced by the nonlinearity of the respiratory system. We used a computational model-based approach to analyse the respiratory airflow during use of HFCC. Methods The computational model, which is based on previous physiological studies and represented by an electrical circuit analogue, was used for simulation of in vivo protocol that shows the nonlinearity of the respiratory system. Besides, airflow was measured during use of HFCC. We compared the simulation results to either the measured data or the previous research, to understand and explain the observations. Results and discussion We could observe two important phenomena during respiration pertaining to the airflow signal oscillation generated by HFCC. The amplitudes of HFCC airflow signals varied depending on spontaneous airflow signals. We used the simulation results to investigate how the nonlinearity of airway resistance, lung capacitance, and inertance of air characterized the respiratory airflow. The simulation results indicated that lung capacitance or the inertance of air is also not a factor in the non-uniformity of HFCC airflow signals. Although not perfect, our circuit analogue model allows us to effectively simulate the nonlinear characteristics of the respiratory system. Conclusion We found that the amplitudes of HFCC airflow signals behave as a function of spontaneous airflow signals. This is due to the nonlinearity of the respiratory system, particularly variations in airway resistance. PMID:15904523

  6. Mechanically induced sudden death in chest wall impact (commotio cordis).

    PubMed

    Link, Mark S

    2003-01-01

    Sudden death due to nonpenetrating chest wall impact in the absence of injury to the ribs, sternum and heart is known as commotio cordis. Although once thought rare, an increasing number of these events have been reported. Indeed, a significant percentage of deaths on the athletic field are due to chest wall impact. Commotio cordis is most frequently observed in young individuals (age 4-18 years), but may also occur in adults. Sudden death is instantaneous or preceded by several seconds of lightheadedness after the chest wall blow. Victims are most often found in ventricular fibrillation, and successful resuscitation is more difficult than expected given the young age, excellent health of the victims, and the absence of structural heart disease. Autopsy examination is notable for the lack of any significant cardiac or thoracic abnormalities. In an experimental model of commotio cordis utilizing anesthetized juvenile swine, ventricular fibrillation can be produced by a 30 mph baseball strike if the strike occurred during the vulnerable period of repolarization, on the upslope of the T-wave. Energy of the impact object was also found to be a critical variable with 40 mph baseballs more likely to cause ventricular fibrillation than velocities less or greater than 40 mph. In addition, more rigid impact objects and blows directly over the center of the chest were more likely to cause ventricular fibrillation. Peak left ventricular pressure generated by the chest wall blow correlated with the risk of ventricular fibrillation. Activation of the K(+)(ATP) channel is a likely cause of the ventricular fibrillation produced by chest wall blows. Successful resuscitation is attainable with early defibrillation.

  7. Different frequencies should be prescribed for different high frequency chest compression machines.

    PubMed

    Milla, Carlos E; Hansen, Leland G; Warwick, Warren J

    2006-01-01

    High frequency chest compression (HFCC) is used for treatment and prevention of the lung diseases characterized by impaired mucus clearance and/or cough, where patients are at risk for acquiring acute bronchitis or pneumonia. The HFCC treatment frequencies may be prescribed according to the manufacturers' generic guidelines or may be determined for each individual patient by a "tuning" method that measures, at the mouth, the air volume displacement and the associated airflows produced at each frequency. Tuning is performed while the patient is breathing normally during the HFCC system operation. After measurements for several breaths at one frequency have been collected, the program randomly selects and measures another frequency until the entire frequency range of the machine being tuned has been sampled. Frequencies range from 6 to 21 Hz for the sine waveform machines and from 6 to 25 Hz for the square waveform machines. Each group of flow signals is digitized and analyzed by the program. For each frequency, the HFCC flow velocities and volumes are computed and averaged. These average flows and volumes are rank ordered; the three frequencies with the highest flows and the three frequencies producing the largest volumes are selected for prescription. If the same frequency is selected as one of the three best frequencies for both flow and volume, the next ranked frequency is selected randomly for flow or volume. Significant differences exist between patients and HFCC machines. In a series of 100 cystic fibrosis (CF) patients with varying degrees of lung disease, we found that the best-ranked frequencies varied from patient to patient and did not correlate with patients' age, gender, height, weight, or spirometry parameters. With the sine waveform, the highest HFCC airflows were between 13 and 20 Hz 82% of the time and the largest HFCC volumes were between 6 and 10 Hz 83% of the time. With the square waveform, both the highest average HFCC flow rates and the largest

  8. Resonant frequency does not predict high-frequency chest compression settings that maximize airflow or volume.

    PubMed

    Luthy, Sarah K; Marinkovic, Aleksandar; Weiner, Daniel J

    2011-06-01

    High-frequency chest compression (HFCC) is a therapy for cystic fibrosis (CF). We hypothesized that the resonant frequency (f(res)), as measured by impulse oscillometry, could be used to determine what HFCC vest settings produce maximal airflow or volume in pediatric CF patients. In 45 subjects, we studied: f(res), HFCC vest frequencies that subjects used (f(used)), and the HFCC vest frequencies that generated the greatest volume (f(vol)) and airflow (f(flow)) changes as measured by pneumotachometer. Median f(used) for 32 subjects was 14 Hz (range, 6-30). The rank order of the three most common f(used) was 15 Hz (28%) and 12 Hz (21%); three frequencies tied for third: 10, 11, and 14 Hz (5% each). Median f(res) for 43 subjects was 20.30 Hz (range, 7.85-33.65). Nineteen subjects underwent vest-tuning to determine f(vol) and f(flow). Median f(vol) was 8 Hz (range, 6-30). The rank order of the three most common f(vol) was: 8 Hz (42%), 6 Hz (32%), and 10 Hz (21%). Median f(flow) was 26 Hz (range, 8-30). The rank order of the three most common f(flow) was: 30 Hz (26%) and 28 Hz (21%); three frequencies tied for third: 8, 14, and 18 Hz (11% each). There was no correlation between f(used) and f(flow) (r(2)  = -0.12) or f(vol) (r(2) = 0.031). There was no correlation between f(res) and f(flow) (r(2)  = 0.19) or f(vol) (r(2) = 0.023). Multivariable analysis showed no independent variables were predictive of f(flow) or f(vol). Vest-tuning may be required to optimize clinical utility of HFCC. Multiple HFCC frequencies may need to be used to incorporate f(flow) and f(vol).

  9. The evaluation of upper body muscle activity during the performance of external chest compressions in simulated hypogravity

    NASA Astrophysics Data System (ADS)

    Krygiel, Rebecca G.; Waye, Abigail B.; Baptista, Rafael Reimann; Heidner, Gustavo Sandri; Rehnberg, Lucas; Russomano, Thais

    2014-04-01

    BACKGROUND: This original study evaluated the electromyograph (EMG) activity of four upper body muscles: triceps brachii, erector spinae, upper rectus abdominis, and pectoralis major, while external chest compressions (ECCs) were performed in simulated Martian hypogravity using a Body Suspension Device, counterweight system, and standard full body cardiopulmonary resuscitation (CPR) mannequin. METHOD: 20 young, healthy male subjects were recruited. One hundred compressions divided into four sets, with roughly six seconds between each set to indicate 'ventilation', were performed within approximately a 1.5 minute protocol. Chest compression rate, depth and number were measured along with the subject's heart rate (HR) and rating of perceived exertion (RPE). RESULTS: All mean values were used in two-tailed t-tests using SPSS to compare +1 Gz values (control) versus simulated hypogravity values. The AHA (2005) compression standards were maintained in hypogravity. RPE and HR increased by 32% (p < 0.001) and 44% (p = 0.002), respectively, when ECCs were performed during Mars simulation, in comparison to +1 Gz. In hypogravity, the triceps brachii showed significantly less activity (p < 0.001) when compared with the other three muscles studied. The comparison of all the other muscles showed no difference at +1 Gz or in hypogravity. CONCLUSIONS: This study was among the first of its kind, however several limitations were faced which hopefully will not exist in future studies. Evaluation of a great number of muscles will allow space crews to focus on specific strengthening exercises within their current training regimes in case of a serious cardiac event in hypogravity.

  10. Compression failure mechanisms of composite structures

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.; Sohi, M.; Moon, S.

    1986-01-01

    An experimental and analytical study was conducted to delineate the compression failure mechanisms of composite structures. The present report summarizes further results on kink band formation in unidirectional composites. In order to assess the compressive strengths and failure modes of fibers them selves, a fiber bundle was embedded in epoxy casting and tested in compression. A total of six different fibers were used together with two resins of different stiffnesses. The failure of highly anisotropic fibers such as Kevlar 49 and P-75 graphite was due to kinking of fibrils. However, the remaining fibers--T300 and T700 graphite, E-glass, and alumina--failed by localized microbuckling. Compressive strengths of the latter group of fibers were not fully utilized in their respective composite. In addition, acoustic emission monitoring revealed that fiber-matrix debonding did not occur gradually but suddenly at final failure. The kink band formation in unidirectional composites under compression was studied analytically and through microscopy. The material combinations selected include seven graphite/epoxy composites, two graphite/thermoplastic resin composites, one Kevlar 49/epoxy composite and one S-glass/epoxy composite.

  11. Mechanical properties of chest protectors and the likelihood of ventricular fibrillation due to commotio cordis.

    PubMed

    Drewniak, Elizabeth I; Spenciner, David B; Crisco, Joseph J

    2007-11-01

    Sudden death resulting from ventricular fibrillation (VF) caused by a nonpenetrating chest wall impact, known as commotio cordis (CC), is the second leading cause of death among young athletes. To date, seven young athletes wearing chest protectors have died from CC. The purpose of this study was to determine whether a relationship exists between mechanical properties of chest protectors and occurrence of VF, previously determined by Weinstock et al., using an established swine model. A servo-hydraulic material tester was used to determine properties of the chest protectors, including displacement, permanent deformation, stiffness, and area of pressure distribution. These properties were then compared with the occurrence of VF. We found that a decreased proportion of hits resulting in VF was significantly associated (R2 = 0.59, p = 0.001) with an increase in the area of pressure distribution. These findings are a limited, but crucial, first step in understanding the prevention of this complex and perplexing phenomenon. PMID:18089926

  12. Detecting changes in respiratory patterns in high frequency chest compression therapy by single-channel blind source separation.

    PubMed

    Zhu, Xiaoming; Parhi, Keshab K; Warwick, Warren J

    2009-01-01

    High Frequency Chest Compression (HFCC) is used as a method to remove the mucus in the airway for Cystic Fibrosis (CF) patients. As the characteristics of the tracheal sound reflect the conditions of airways, in this paper, we propose a novel method to evaluate the respiratory patterns in HFCC therapy by using single channel tracheal sounds only. The difficulty of analyzing tracheal sounds lies in that it has a wider frequency band than the air flow at the mouth, and is always corrupted by other biomedical signals and noises. During HFCC therapy, the tracheal sound is also affected by the HFCC machine noise. For this reason, it is difficult to extract respiratory patterns and other related features by traditional filtering techniques. In this paper, we demonstrate use of single-channel independent component analysis to extract respiratory patterns from the tracheal sounds before, during and after HFCC therapy, and use basis features in the tracheal sound to detect the change in respiratory patterns.

  13. Mechanisms and Clinical Management of Ventricular Arrhythmias following Blunt Chest Trauma

    PubMed Central

    Wolbrom, Daniel H.; Rahman, Aleef; Tschabrunn, Cory M.

    2016-01-01

    Nonpenetrating, blunt chest trauma is a serious medical condition with varied clinical presentations and implications. This can be the result of a dense projectile during competitive and recreational sports but may also include other etiologies such as motor vehicle accidents or traumatic falls. In this setting, the manifestation of ventricular arrhythmias has been observed both acutely and chronically. This is based on two entirely separate mechanisms and etiologies requiring different treatments. Ventricular fibrillation can occur immediately after chest wall injury (commotio cordis) and requires rapid defibrillation. Monomorphic ventricular tachycardia can develop in the chronic stage due to underlying structural heart disease long after blunt chest injury. The associated arrhythmogenic tissue may be complex and provides the necessary substrate to form a reentrant VT circuit. Ventricular tachycardia in the absence of overt structural heart disease appears to be focal in nature with rapid termination during ablation. Regardless of the VT mechanism, patients with recurrent episodes, despite antiarrhythmic medication in the chronic stage following blunt chest injury, are likely to require ablation to achieve VT control. This review article will describe the mechanisms, pathophysiology, and treatment of ventricular arrhythmias that occur in both the acute and chronic stages following blunt chest trauma. PMID:26981308

  14. Systematic investigation of compression mechanisms of clinoenstatite

    NASA Astrophysics Data System (ADS)

    Lazarz, J. D.; Dera, P.; Bina, C. R.; Jacobsen, S. D.

    2015-12-01

    Pyroxenes are a major component of the Earth's upper mantle and believed to be stable to approximately 16 GPa, along the oceanic geotherm. However, under certain conditions such as subducting slabs, it is possible to carry pyroxenes to much greater depths within the mantle. Pyroxenes penetrating the mantle to such depths could potentially undergo further phase transitions which could impact subducting slab mineralogy and mantle dynamics. The compression behavior of clinopyroxenes has been well characterized up to approximately 25 GPa with much of the work being focused on Ca-rich cpx. Beyond 10 GPa previous studies have published equations of state but there is a general lack of structure determinations. Ca-rich clinopyroxenes crystallize in the C2/c space group while Ca-poor clinopyroxenes crystalize in P21/c. It has been shown that P21/c clinopyroxenes reversibly transform to C2/c upon increased pressure, temperature, and M2 site cation size. The critical pressure for this transition is exceedingly compositionally dependent at 6.5 GPa and 1.7 GPa for clinoenstatite and clinoferrosilite, respectively. The strong compositional dependence of phase transitions in pyroxenes is motivation for a more complete understanding of compression mechanisms within the broad pyroxene category. By using in situ x-ray diffraction and diamond anvil cells to compress single-crystal clinoenstatite up to 50 GPa this study aims to expand the understanding of Ca-poor clinopyroxene compression mechanisms and elasticity. Here we report a fully reversible high-pressure phase in the P21/c space group found at approximately 45 GPa.

  15. Comparison of the Pentax Airwayscope, Glidescope Video Laryngoscope, and Macintosh Laryngoscope During Chest Compression According to Bed Height.

    PubMed

    Kim, Wonhee; Lee, Yoonje; Kim, Changsun; Lim, Tae Ho; Oh, Jaehoon; Kang, Hyunggoo; Lee, Sanghyun

    2016-02-01

    We aimed to investigate whether bed height affects intubation performance in the setting of cardiopulmonary resuscitation and which type of laryngoscope shows the best performance at each bed height.A randomized crossover manikin study was conducted. Twenty-one participants were enrolled, and they were randomly allocated to 2 groups: group A (n = 10) and group B (n = 11). The participants underwent emergency endotracheal intubation (ETI) using the Airwayscope (AWS), Glidescope video laryngoscope, and Macintosh laryngoscope in random order while chest compression was performed. Each ETI was conducted at 2 levels of bed height (minimum bed height: 68.9  cm and maximum bed height: 101.3 cm). The primary outcomes were the time to intubation (TTI) and the success rate of ETI. The P value for statistical significance was set at 0.05 and 0.017 in post-hoc test.The success rate of ETI was always 100% regardless of the type of laryngoscope or the bed height. TTI was not significantly different between the 2 bed heights regardless of the type of laryngoscope (all P > 0.05). The time for AWS was the shortest among the 3 laryngoscopes at both bed heights (13.7  ±  3.6 at the minimum bed height and 13.4  ±  4.7 at the maximum bed height) (all P < 0.017). The TTI of Glidescope video laryngoscope was not significantly shorter than that of Macintosh laryngoscope at the minimum height (17.6  ±  4.0 vs 19.6  ±  4.8; P = 0.02).The bed height, whether adjusted to the minimum or maximum setting, did not affect intubation performance. In addition, regardless of the bed height, the intubation time with the video laryngoscopes, especially AWS, was significantly shorter than that with the direct laryngoscope during chest compression.

  16. Clinical study on VATS combined mechanical ventilation treatment of ARDS secondary to severe chest trauma

    PubMed Central

    Qi, Yongjun

    2016-01-01

    The aim of the study was to investigate the clinical effects of microinvasive video-assisted thoracoscopic surgery (VATS) combined with mechanical ventilation in the treatment of acute respiratory distress syndrome (ARDS) secondary to severe chest trauma. A total of 62 patients with ARDS secondary to severe chest trauma were divided into the observation and control groups. The patients in the observation groups were treated with VATS combined with early mechanical ventilation while patients in the control group were treated using routine open thoracotomy combined with early mechanical ventilation. Compared to the controls, the survival rate of the observation group was significantly higher. The average operation time of the observation group was significantly shorter than that of the control group, and the incidence of complications in the perioperative period of the observation group was significantly lower than that of the control group (p<0.05). The average application time of the observation group was significantly shorter than that of the control group, and the incidence of ventilator-associated complications was significantly lower than that of the control group (p<0.05). In conclusion, a reasonable understanding of the indications and contraindications of VATS, combined with early mechanical treatment significantly improved the success rate of the treatment of ARDS patients secondary to severe chest trauma and reduced the complications. PMID:27446317

  17. High-frequency and low-frequency chest compression: effects on lung water secretion, mucus transport, heart rate, and blood pressure using a trapezoidal source pressure waveform.

    PubMed

    O'Clock, George D; Lee, Yong Wan; Lee, Jongwong; Warwick, Warren J

    2012-01-01

    High-frequency chest compression (HFCC), using an appropriate source (pump) waveform for frequencies at or above 3 Hz, can enhance pulmonary clearance for patients with cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). Using a trapezoidal HFCC source pressure waveform, secretion of water from epithelial tissue and transport of mucus through lung airways can be enhanced for patients with CF and COPD. At frequencies below 3 Hz, low-frequency chest compression (LFCC) appears to have a significant impact on the cardiovascular system. For a trapezoidal source pressure waveform at frequencies close to 1 Hz, LFCC produces amplitude or intensity variations in various components of the electrocardiogram time-domain waveform, produces changes at very low frequencies associated with the electrocardiogram frequency spectra (indicating enhanced parasympathetic nervous system activity), and promotes a form of heart rate synchronization. It appears that LFCC can also provide additional cardiovascular benefits by reducing peak and average systolic and diastolic blood pressure for patients with hypertension.

  18. 50% duty cycle may be inappropriate to achieve a sufficient chest compression depth when cardiopulmonary resuscitation is performed by female or light rescuers

    PubMed Central

    Lee, Chang Jae; Chung, Tae Nyoung; Bae, Jinkun; Kim, Eui Chung; Choi, Sung Wook; Kim, Ok Jun

    2015-01-01

    Objective Current guidelines for cardiopulmonary resuscitation recommend chest compressions (CC) during 50% of the duty cycle (DC) in part because of the ease with which individuals may learn to achieve it with practice. However, no consideration has been given to a possible interaction between DC and depth of CC, which has been the subject of recent study. Our aim was to determine if 50% DC is inappropriate to achieve sufficient chest compression depth for female and light rescuers. Methods Previously collected CC data, performed by senior medical students guided by metronome sounds with various down-stroke patterns and rates, were included in the analysis. Multiple linear regression analysis was performed to determine the association between average compression depth (ACD) with average compression rate (ACR), DC, and physical characteristics of the performers. Expected ACD was calculated for various settings. Results DC, ACR, body weight, male sex, and self-assessed physical strength were significantly associated with ACD in multivariate analysis. Based on our calculations, with 50% of DC, only men with ACR of 140/min or faster or body weight over 74 kg with ACR of 120/min can achieve sufficient ACD. Conclusion A shorter DC is independently correlated with deeper CC during simulated cardiopulmonary resuscitation. The optimal DC recommended in current guidelines may be inappropriate for achieving sufficient CD, especially for female or lighter-weight rescuers.

  19. A mechanical chest compressor closed-loop controller with an effective trade-off between blood flow improvement and ribs fracture reduction.

    PubMed

    Zhang, Guang; Wu, Taihu; Song, Zhenxing; Wang, Haitao; Lu, Hengzhi; Wang, Yalin; Wang, Dan; Chen, Feng

    2015-06-01

    Chest compression (CC) is a significant emergency medical procedure for maintaining circulation during cardiac arrest. Although CC produces the necessary blood flow for patients with heart arrest, improperly deep CC will contribute significantly to the risk of chest injury. In this paper, an optimal CC closed-loop controller for a mechanical chest compressor (OCC-MCC) was developed to provide an effective trade-off between the benefit of improved blood perfusion and the risk of ribs fracture. The trade-off performance of the OCC-MCC during real automatic mechanical CCs was evaluated by comparing the OCC-MCC and the traditional mechanical CC method (TMCM) with a human circulation hardware model based on hardware simulations. A benefit factor (BF), risk factor (RF) and benefit versus risk index (BRI) were introduced in this paper for the comprehensive evaluation of risk and benefit. The OCC-MCC was developed using the LabVIEW control platform and the mechanical chest compressor (MCC) controller. PID control is also employed by MCC for effective compression depth regulation. In addition, the physiological parameters model for MCC was built based on a digital signal processor for hardware simulations. A comparison between the OCC-MCC and TMCM was then performed based on the simulation test platform which is composed of the MCC, LabVIEW control platform, physiological parameters model for MCC and the manikin. Compared with the TMCM, the OCC-MCC obtained a better trade-off and a higher BRI in seven out of a total of nine cases. With a higher mean value of cardiac output (1.35 L/min) and partial pressure of end-tidal CO2 (15.7 mmHg), the OCC-MCC obtained a larger blood flow and higher BF than TMCM (5.19 vs. 3.41) in six out of a total of nine cases. Although it is relatively difficult to maintain a stable CC depth when the chest is stiff, the OCC-MCC is still superior to the TMCM for performing safe and effective CC during CPR. The OCC-MCC is superior to the TMCM in

  20. [Chest physical therapy of the distal lung. Mechanical basis of a new paradigm].

    PubMed

    Postiaux, G

    2014-06-01

    Recent medical literature has shown that there has been renewed interest focused on the small airways deep in the lung tissue. Although there is involvement of the distal airways at an early stage in mucus secreting lung diseases, no specific chest physical therapy (CPT) manoeuver has been proposed for small airways clearance. A four-tier classification of CPT has been established with identification of its benefits at each level of a monoalveolar respiratory tract model. The usual expiratory techniques directed towards the upper and middle respiratory tract are not applicable to the small airways and new paradigm is proposed appropriate to their specific mechanical characteristics. This comprises a slow resistive inspiratory manoeuver in the lateral position. Clinical auscultation of the lung is the cornerstone of the validation and follow-up of the technique. PMID:25012039

  1. Which Fingers Should We Perform Two-Finger Chest Compression Technique with When Performing Cardiopulmonary Resuscitation on an Infant in Cardiac Arrest?

    PubMed Central

    2016-01-01

    This study compared the effectiveness two-finger chest compression technique (TFCC) performed using the right vs. left hand and the index-middle vs. middle-ring fingers. Four different finger/hand combinations were tested randomly in 30 healthcare providers performing TFCC (Test 1: the right index-middle fingers; Test 2: the left index-middle fingers; Test 3: the right middle-ring fingers; Test 4: the left middle-ring fingers) using two cross-over trials. The “patient” was a 3-month-old-infant-sized manikin. Each experiment consisted of cardiopulmonary resuscitation (CPR) consisting of 2 minutes of 30:2 compression: ventilation performed by one rescuer on a manikin lying on the floor as if in cardiac arrest. Ventilations were performed using the mouth-to-mouth method. Compression and ventilation data were collected during the tests. The mean compression depth (MCD) was significantly greater in TFCC performed with the index-middle fingers than with the middle-ring fingers regardless of the hand (95% confidence intervals; right hand: 37.8–40.2 vs. 35.2–38.6 mm, P = 0.002; left hand: 36.9–39.2 vs. 35.5–38.1 mm, P = 0.003). A deeper MCD was achieved with the index-middle fingers of the right versus the left hand (P = 0.004). The ratio of sufficiently deep compressions showed the same patterns. There were no significant differences in the other data. The best performance of TFCC in simulated 30:2 compression: ventilation CPR performed by one rescuer on an infant in cardiac arrest lying on the floor was obtained using the index-middle fingers of the right hand. Clinical Trial Registry at the Clinical Research Information Service (KCT0001515). PMID:27247512

  2. The anisotropic compressive mechanical properties of the rabbit patellar tendon.

    PubMed

    Williams, Lakiesha N; Elder, Steven H; Bouvard, J L; Horstemeyer, M F

    2008-01-01

    In this study, we examine the transverse and longitudinal compressive mechanical behavior of the rabbit patellar tendon. The anisotropic compressive properties are of interest, because compression occurs where the tendon attaches to bone and where the tendon wraps around bone leading to the development of fibro-cartilaginous matrices. We quantified the time dependent viscoelastic and anisotropic behavior of the tendon under compression. For both orientations, sections of patellar tendon were drawn from mature male white New Zealand rabbits in preparation for testing. The tendons were sequentially compressed to 40% strain at strain rates of 0.1, 1 and 10% strain(s) using a computer-controlled stepper motor driven device under physiological conditions. Following monotonic loading, the tendons were subjected to stress relaxation. The tendon equilibrium compressive modulus was quantified to be 19.49+/-11.46 kPa for the transverse direction and 1.11+/-0.57 kPa for the longitudinal direction. The compressive modulus at applied strain rates of 0.1, 1 and 10% strain(s) in the transverse orientation were 13.48+/-2.31, 18.24+/-4.58 and 20.90+/-8.60 kPa, respectively. The compressive modulus at applied strain rates of 0.1, 1 and 10% strain/s in the longitudinal orientation were 0.19+/-0.11, 1.27+/-1.38 and 3.26+/-3.49 kPa, respectively. The modulus values were almost significantly different for the examination of the effect of orientation on the equilibrium modulus (p=0.054). Monotonic loading of the tendon showed visual differences of the strain rate dependency; however, no significant difference was shown in the statistical analysis of the effect of strain rate on compressive modulus. The statistical analysis of the effect of orientation on compressive modulus showed a significant difference. The difference shown in the orientation analysis validated the anisotropic nature of the tendon. PMID:19065006

  3. Computerized detection of vertebral compression fractures on lateral chest radiographs: Preliminary results with a tool for early detection of osteoporosis

    SciTech Connect

    Kasai, Satoshi; Li Feng; Shiraishi, Junji; Li Qiang; Doi, Kunio

    2006-12-15

    Vertebral fracture (or vertebral deformity) is a very common outcome of osteoporosis, which is one of the major public health concerns in the world. Early detection of vertebral fractures is important because timely pharmacologic intervention can reduce the risk of subsequent additional fractures. Chest radiographs are used routinely for detection of lung and heart diseases, and vertebral fractures can be visible on lateral chest radiographs. However, investigators noted that about 50% of vertebral fractures visible on lateral chest radiographs were underdiagnosed or under-reported, even when the fractures were severe. Therefore, our goal was to develop a computerized method for detection of vertebral fractures on lateral chest radiographs in order to assist radiologists' image interpretation and thus allow the early diagnosis of osteoporosis. The cases used in this study were 20 patients with severe vertebral fractures and 118 patients without fractures, as confirmed by the consensus of two radiologists. Radiologists identified the locations of fractured vertebrae, and they provided morphometric data on the vertebral shape for evaluation of the accuracy of detecting vertebral end plates by computer. In our computerized method, a curved search area, which included a number of vertebral end plates, was first extracted automatically, and was straightened so that vertebral end plates became oriented horizontally. Edge candidates were enhanced by use of a horizontal line-enhancement filter in the straightened image, and a multiple thresholding technique, followed by feature analysis, was used for identification of the vertebral end plates. The height of each vertebra was determined from locations of identified vertebral end plates, and fractured vertebrae were detected by comparison of the measured vertebral height with the expected height. The sensitivity of our computerized method for detection of fracture cases was 95% (19/20), with 1.03 (139/135) false

  4. Clinical evaluation of the AutoPulse automated chest compression device for out-of-hospital cardiac arrest in the northern district of Shanghai, China

    PubMed Central

    Chen, Yuanzhuo; Peng, Hu; Chen, Yanqing; Zhuang, Yugang; Zhou, Shuqin

    2016-01-01

    Introduction Whether the AutoPulse automated chest compression device is worthy of clinical use for out-of-hospital cardiac arrest (OHCA) remains controversial. A prospective controlled study was conducted to evaluate the effect of AutoPulse versus manual chest compression for cardiopulmonary resuscitation (CPR) of OHCA patients in the northern district of Shanghai, China. Material and methods A total of 133 patients with OHCA who were treated at the Emergency Medical Center of the Tenth People's Hospital Affiliated with Tongji University between March 2011 and March 2012 were included. The patients were randomly assigned to the Manual CPR (n = 64) and AutoPulse CPR groups (n = 69) in accordance with the approach of chest compression received. The primary outcome measure was return of spontaneous circulation (ROSC), and the secondary outcome measures included 24-h survival rate, hospital discharge rate, and neurological prognosis at hospital discharge. Results The ROSC rate of patients with OHCA was significantly higher in the AutoPulse CPR group than in the Manual CPR group (44.9% vs. 23.4%; p = 0.009). The 24-h survival rate of OHCA patients was significantly higher in the AutoPulse CPR group than in the Manual CPR group (39.1% vs. 21.9%; p = 0.03). The hospital discharge rate of the patients with OHCA was significantly higher in the AutoPulse CPR group than in the Manual CPR group (18.8% vs. 6.3%; p = 0.03). The proportion of patients with OHCA and a cerebral performance category score of 1 or 2 points at hospital discharge was higher in the AutoPulse CPR group than in the Manual CPR group, but the difference was not statistically significant (16.2% vs. 13.4%, p = 1.00). Conclusions Use of the AutoPulse increases CPR success and survival rates in patients with OHCA, but its ability to improve cerebral performance requires further evaluation. PMID:27279849

  5. Passive mechanics of lung and chest wall in patients who failed or succeeded in trials of weaning.

    PubMed

    Jubran, A; Tobin, M J

    1997-03-01

    In an accompanying article (Jubran, et al., Am. J. Respir. Crit. Care Med. 155:906-915), we report that patients with chronic obstructive pulmonary disease (COPD) who failed a trial of weaning from mechanical ventilation developed worsening of pulmonary mechanics compared with patients who tolerated the trial and were extubated. We wondered whether the greater derangements in pulmonary mechanics in the weaning failure patients are evident ever before undertaking the weaning trial. We measured mechanics of the respiratory system, lung, and chest wall during passive ventilation at usual ventilator settings in 12 patients who went on to fail a weaning trial and in 12 patients who were successfully weaned. No differences in the resistances of the respiratory system, lung, and chest wall were observed between the two groups or when the resistances were separated into the components derived from ohmic resistance and viscoelastic behavior/time-constant inhomogeneities. Likewise, the groups did not differ in terms of static elastance and dynamic intrinsic positive end-expiratory pressure (PEEPi) of the respiratory system and the respective lung and chest wall components or in terms of dynamic elastances of the respiratory system and chest wall. The failure group had a higher dynamic elastance of the lung than the success group (p < 0.01), but the individual values showed considerable overlap among the patients in the two groups so limiting its usefulness in signaling a patient's ability to sustain spontaneous ventilation. Thus, mechanics of the respiratory system and its lung and chest wall components during passive ventilation did not satisfactorily discriminate between patients who failed a weaning trial and those successfully weaned, and, thus, are unlikely to be useful in signaling a patient's ability to tolerate the discontinuation of mechanical ventilation.

  6. Development of a smart backboard system for real-time feedback during CPR chest compression on a soft back support surface.

    PubMed

    Gohier, Francis; Dellimore, Kiran; Scheffer, Cornie

    2013-01-01

    The quality of cardiopulmonary resuscitation (CPR) is often inconsistent and frequently fails to meet recommended guidelines. One promising approach to address this problem is for clinicians to use an active feedback device during CPR. However, one major deficiency of existing feedback systems is that they fail to account for the displacement of the back support surface during chest compression (CC), which can be important when CPR is performed on a soft surface. In this study we present the development of a real-time CPR feedback system based on an algorithm which uses force and dual-accelerometer measurements to provide accurate estimation of the CC depth on a soft surface, without assuming full chest decompression. Based on adult CPR manikin tests it was found that the accuracy of the estimated CC depth for a dual accelerometer feedback system is significantly better (7.3% vs. 24.4%) than for a single accelerometer system on soft back support surfaces, in the absence or presence of a backboard. In conclusion, the algorithm used was found to be suitable for a real-time, dual accelerometer CPR feedback application since it yielded reasonable accuracy in terms of CC depth estimation, even when used on a soft back support surface.

  7. Compressive fracture morphology and mechanism of metallic glass

    NASA Astrophysics Data System (ADS)

    Qu, R. T.; Zhang, Z. F.

    2013-11-01

    We quantitatively investigated the fracture morphologies of Zr52.5Cu17.9Ni14.6Al10Ti5 and Pd78Cu6Si16 metallic glasses (MGs) under compression. The characteristic features of the compressive fracture morphology were captured, and the shear vein patterns were found to be not a one-to-one correspondence between two opposing fracture surfaces in an identical sample. This finding experimentally confirms that the compressive failure behaves in a fracture mode of pure shear (mode II). Quantitative measurements show that a ˜1 μm thickness layer with materials not only inside but also adjacent to the major shear band contributes to the formation of shear vein patterns. The critical shear strain to break a shear band was found to be more than 105% and higher in more ductile MGs under compression than tension. Estimation on the temperature rise at the fracture moment indicates that only ˜5% of the total elastic energy stored in the sample converts into the heat required for melting the layer to form the vein patterns. The mode II fracture toughness was also estimated based on the quantitative measurements of shear vein pattern and found larger than the mode I fracture toughness. Finally, the deformation and fracture mechanisms of MGs under tension and compression were compared and discussed. These results may improve the understanding on the fracture behaviors and mechanisms of MGs and may provide instructions on future design for ductile MGs with high resistance for fracture.

  8. Lung and chest wall mechanics in patients with acquired immunodeficiency syndrome and severe Pneumocystis carinii pneumonia.

    PubMed

    D'Angelo, E; Calderini, E; Robatto, F M; Puccio, P; Milic-Emili, J

    1997-10-01

    The aim of this study was to assess the mechanical characteristics of the respiratory system in patients with acquired immune deficiency syndrome (AIDS) and acute respiratory distress syndrome (ARDS) caused by Pneumocystis carinii pneumonia (PCP). In 12 mechanically ventilated patients, total respiratory system mechanics was assessed using the technique of rapid airway occlusion during constant flow inflation, and was partitioned into lung and chest wall components using the oesophageal balloon technique. We measured interrupter resistance (Rint), which mainly reflects airway resistance, additional resistance (deltaR) due to viscoelastic behaviour and time constant inequalities, and static elastance (Est). In addition, the static inflation volume-pressure (V-P) curve was assessed. In eight patients, computed tomography scans were performed within 2 days of the assessment of respiratory mechanics. Compared to values reported in the literature for normal subjects, Est and deltaR were markedly increased in AIDS patients with PCP, whilst Rint exhibited a relatively smaller increase. These changes, which involved only the lung and airways, were mainly due to the reduction of ventilated lung units, but additional factors were involved to cause independent modifications of lung stiffness, airway calibre, and viscoelastic properties. The changes in Rint, deltaR, and Est were similar to those observed in other studies on patients with ARDS of different aetiologies. At variance with common observations in the latter patients, none of the AIDS patients with PCP exhibited an inflection point on the static inflation V-P curve, suggesting little or no alveolar recruitment during lung inflation. This finding could be related to the distinctive histopathology of Pneumocystis carinii pneumonia. Indeed, computed tomography revealed homogeneous diffuse interstitial and alveolar infiltration rather than the dense, dependent opacities observed in other studies on acute respiratory

  9. Mechanical Properties of Murine and Porcine Ocular Tissues in Compression

    PubMed Central

    Worthington, Kristan S.; Wiley, Luke A.; Bartlett, Alexandra M.; Stone, Edwin M.; Mullins, Robert F.; Salem, Aliasger K.; Guymon, C. Allan; Tucker, Budd A.

    2014-01-01

    Sub-retinal implantation of foreign materials is becoming an increasingly common feature of novel therapies for retinal dysfunction. The ultimate compatibility of implants depends not only on their in vitro chemical compatibility, but also on how well the mechanical properties of the material match those of the native tissue. In order to optimize the mechanical properties of retinal implants, the mechanical properties of the mammalian retina itself must be carefully characterized. In this study, the compressive moduli of eye tissues, especially the retina, were probed using a dynamic mechanical analysis instrument in static mode. The retinal compressive modulus was lower than that of the sclera or cornea, but higher than that of the RPE and choroid. Compressive modulus remained relatively stable with age. Conversely, apparent retinal softening occurred at an early age in mice with inherited retinal degeneration. Compressive modulus is an important consideration for the design of retinal implants. Polymer scaffolds with moduli that are substantially different than that of the native tissue in which they will ultimately reside will be less likely to aid in the differentiation and development of the appropriate cell types in vitro and will have reduced biocompatibility in vivo. PMID:24613781

  10. Mechanical properties of murine and porcine ocular tissues in compression.

    PubMed

    Worthington, Kristan S; Wiley, Luke A; Bartlett, Alexandra M; Stone, Edwin M; Mullins, Robert F; Salem, Aliasger K; Guymon, C Allan; Tucker, Budd A

    2014-04-01

    Sub-retinal implantation of foreign materials is becoming an increasingly common feature of novel therapies for retinal dysfunction. The ultimate compatibility of implants depends not only on their in vitro chemical compatibility, but also on how well the mechanical properties of the material match those of the native tissue. In order to optimize the mechanical properties of retinal implants, the mechanical properties of the mammalian retina itself must be carefully characterized. In this study, the compressive moduli of eye tissues, especially the retina, were probed using a dynamic mechanical analysis instrument in static mode. The retinal compressive modulus was lower than that of the sclera or cornea, but higher than that of the RPE and choroid. Compressive modulus remained relatively stable with age. Conversely, apparent retinal softening occurred at an early age in mice with inherited retinal degeneration. Compressive modulus is an important consideration for the design of retinal implants. Polymer scaffolds with moduli that are substantially different than that of the native tissue in which they will ultimately reside will be less likely to aid in the differentiation and development of the appropriate cell types in vitro and will have reduced biocompatibility in vivo. PMID:24613781

  11. Poroelastic Mechanical Effects of Hemicelluloses on Cellulosic Hydrogels under Compression

    PubMed Central

    Lopez-Sanchez, Patricia; Cersosimo, Julie; Wang, Dongjie; Flanagan, Bernadine; Stokes, Jason R.; Gidley, Michael J.

    2015-01-01

    Hemicelluloses exhibit a range of interactions with cellulose, the mechanical consequences of which in plant cell walls are incompletely understood. We report the mechanical properties of cell wall analogues based on cellulose hydrogels to elucidate the contribution of xyloglucan or arabinoxylan as examples of two hemicelluloses displaying different interactions with cellulose. We subjected the hydrogels to mechanical pressures to emulate the compressive stresses experienced by cell walls in planta. Our results revealed that the presence of either hemicellulose increased the resistance to compression at fast strain rates. However, at slow strain rates, only xyloglucan increased composite strength. This behaviour could be explained considering the microstructure and the flow of water through the composites confirming their poroelastic nature. In contrast, small deformation oscillatory rheology showed that only xyloglucan decreased the elastic moduli. These results provide evidence for contrasting roles of different hemicelluloses in plant cell wall mechanics and man-made cellulose-based composite materials. PMID:25794048

  12. Mechanisms of compressive failure in woven composites and stitched laminates

    NASA Technical Reports Server (NTRS)

    Cox, B. N.; Dadkhah, M. S.; Inman, R. V.; Morris, W. L.; Schroeder, S.

    1992-01-01

    Stitched laminates and angle interlock woven composites have been studied in uniaxial, in-plane, monotonic compression. Failure mechanisms have been found to depend strongly on both the reinforcement architecture and the degree of constraint imposed by the loading grips. Stitched laminates show higher compressive strength, but are brittle, possessing no load bearing capacity beyond the strain for peak load. Post-mortem inspection shows a localized shear band of buckled and broken fibers, which is evidently the product of an unstably propagating kink band. Similar shear bands are found in the woven composites if the constraint of lateral displacements is weak; but, under strong constraint, damage is not localized but distributed throughout the gauge section. While the woven composites tested are weaker than the stitched laminates, they continue to bear significant loads to compressive strains of approx. 15 percent, even when most damage is confined to a shear band.

  13. Cell death induced by mechanical compression on engineered muscle results from a gradual physiological mechanism.

    PubMed

    Wu, Yabin; van der Schaft, Daisy W J; Baaijens, Frank P; Oomens, Cees W J

    2016-05-01

    Deep tissue injury (DTI), a type of pressure ulcer, arises in the muscle layers adjacent to bony prominences due to sustained mechanical loading. DTI presents a serious problem in the clinic, as it is often not visible until reaching an advanced stage. One of the causes can be direct mechanical deformation of the muscle tissue and cell. The mechanism of cell death induced by mechanical compression was studied using bio-artificial skeletal muscle tissues. Compression was applied by placing weights on top of the constructs. The morphological changes of the cytoskeleton and the phosphorylation of mitogen-activated protein kinases (MAPK) under compression were investigated. Moreover, inhibitors for each of the three major MAPK groups, p38, ERK, and JNK, were applied separately to look at their roles in the compression caused apoptosis and necrosis. The present study for the first time showed that direct mechanical compression activates MAPK phosphorylation. Compression also leads to a gradual destruction of the cytoskeleton. The percentage apoptosis is strongly reduced by p38 and JNK inhibitors down to the level of the unloaded group. This phenomenon could be observed up to 24h after initiation of compression. Therefore, cell death in bio-artificial muscle tissue caused by mechanical compression is primarily caused by a physiological mechanism, rather than through a physical mechanism which kills the cell directly. These findings reveal insight of muscle cell death under mechanical compression. Moreover, the result indicates a potential clinical solution to prevent DTI by pre-treating with p38 or/and JNK inhibitors. PMID:26961799

  14. Tuning and synthesis of semiconductor nanostructures by mechanical compression

    DOEpatents

    Fan, Hongyou; Li, Binsong

    2015-11-17

    A mechanical compression method can be used to tune semiconductor nanoparticle lattice structure and synthesize new semiconductor nanostructures including nanorods, nanowires, nanosheets, and other three-dimensional interconnected structures. II-VI or IV-VI compound semiconductor nanoparticle assemblies can be used as starting materials, including CdSe, CdTe, ZnSe, ZnS, PbSe, and PbS.

  15. Statistical mechanics approach to 1-bit compressed sensing

    NASA Astrophysics Data System (ADS)

    Xu, Yingying; Kabashima, Yoshiyuki

    2013-02-01

    Compressed sensing is a framework that makes it possible to recover an N-dimensional sparse vector x∈RN from its linear transformation y∈RM of lower dimensionality M < N. A scheme further reducing the data size of the compressed expression by using only the sign of each entry of y to recover x was recently proposed. This is often termed 1-bit compressed sensing. Here, we analyze the typical performance of an l1-norm-based signal recovery scheme for 1-bit compressed sensing using statistical mechanics methods. We show that the signal recovery performance predicted by the replica method under the replica symmetric ansatz, which turns out to be locally unstable for modes breaking the replica symmetry, is in good consistency with experimental results of an approximate recovery algorithm developed earlier. This suggests that the l1-based recovery problem typically has many local optima of a similar recovery accuracy, which can be achieved by the approximate algorithm. We also develop another approximate recovery algorithm inspired by the cavity method. Numerical experiments show that when the density of nonzero entries in the original signal is relatively large the new algorithm offers better performance than the abovementioned scheme and does so with a lower computational cost.

  16. Damage mechanisms in uniaxial compression of single enamel rods.

    PubMed

    An, Bingbing; Wang, Raorao; Arola, Dwayne; Zhang, Dongsheng

    2015-02-01

    Enamel possesses a complex hierarchical structure, which bestows this tissue with unique mechanical properties. In this study, the mechanical behavior of single enamel rods was investigated under uniaxial compression. Numerical simulations were also performed using micromechanics models for individual enamel rods to identify the damage mechanisms contributing to the constitutive behavior. Experimental results showed that the single rods exhibited an elastic modulus ranging from 10~31 GPa, and that they undergo post-yield strain-hardening. The primary damage mode consisted of delamination within the assembly of mineral crystals. Results from numerical simulations suggest that strain localization within individual rods is responsible for the observed delamination, which is believed to arise from the non-uniform arrangement of mineral crystals. This mechanism was independent of mineral morphology and properties. The non-uniform crystal arrangement results in friction between crystals with different inclination angles and is believed to be responsible for the post-yield strain hardening behavior. PMID:25460920

  17. Return of spontaneous Circulation Is Not Affected by Different Chest Compression Rates Superimposed with Sustained Inflations during Cardiopulmonary Resuscitation in Newborn Piglets

    PubMed Central

    Li, Elliott S.; Cheung, Po-Yin; Lee, Tze-Fun; Lu, Min; O'Reilly, Megan

    2016-01-01

    Objective Recently, sustained inflations (SI) during chest compression (CC) have been suggested as an alternative to the current approach during neonatal resuscitation. However, the optimal rate of CC during SI has not yet been established. Our aim was to determine whether different CC rates during SI reduce time to return of spontaneous circulation (ROSC) and improve hemodynamic recovery in newborn piglets with asphyxia-induced bradycardia. Intervention and measurements Term newborn piglets were anesthetized, intubated, instrumented and exposed to 45-min normocapnic hypoxia followed by asphyxia. Resuscitation was initiated when heart rate decreased to 25% of baseline. Piglets were randomized into three groups: CC superimposed by SI at a rate of 90 CC per minute (SI+CC 90, n = 8), CC superimposed by SI at a rate of 120 CC per minute (SI+CC 120, n = 8), or a sham group (n = 6). Cardiac function, carotid blood flow, cerebral oxygenation and respiratory parameters were continuously recorded throughout the experiment. Main results Both treatment groups had similar time of ROSC, survival rates, hemodynamic and respiratory parameters during cardiopulmonary resuscitation. The hemodynamic recovery in the subsequent 4h was similar in both groups and was only slightly lower than sham-operated piglets at the end of experiment. Conclusion Newborn piglets resuscitated by SI+CC 120 did not show a significant advantage in ROSC, survival, and hemodynamic recovery as compared to those piglets resuscitated by SI+CC 90. PMID:27304210

  18. Levofloxacin decreased chest wall mechanical inhomogeneities and airway and vascular remodeling in rats with induced hepatopulmonary syndrome.

    PubMed

    Gaio, Eduardo; Amado, Veronica; Rangel, Leonardo; Huang, Wilson; Storck, Rodrigo; Melo-Silva, César Augusto

    2013-12-01

    The administration of antibiotics decreases bacterial translocation, reduces the activity of nitric oxide synthase and improves the gas exchange of hepatopulmonary syndrome (HPS) in rats. We hypothesized that levofloxacin could reduce HPS-induced respiratory mechanical inhomogeneities and airway and pulmonary vascular remodeling. We assessed the respiratory mechanical properties and lung tissue structure in 24 rats assigned to the control, HPS (eHPS) and HPS+levofloxacin (eHPS+L) groups. The administration of levofloxacin reduced the HPS-induced chest wall but not the lung mechanical inhomogeneities. The eHPS airway proportion of elastic fibers increased 20% but was similar between the control and eHPS+L groups. The eHPS vascular collagen increased 25% in eHPS but was similar between the control and eHPS+L groups. Compared to the control group, the vascular proportion of elastic fibers of the eHPS and eHPS+L groups increased by 60% and 16%, respectively. The administration of levofloxacin decreased the HPS-induced chest wall mechanical inhomogeneities and airway and vascular remodeling. PMID:23994178

  19. A mechanism for the compressive ignition of liquid monopropellants

    NASA Technical Reports Server (NTRS)

    Morrison, W. F.; Knapton, J. D.; Mandzy, J.

    1980-01-01

    Possible mechanisms for compressive ignition of liquid monopropellants are discussed. These mechanisms all involve the collapse of a gas filled bubble imbedded in the liquid. A model of the collapse of a gas bubble in an incompressible liquid and the combustion of the surrounding liquid after ignition occurs is presented. The effect of gas covolume, liquid density, the adiabatic exponent, rate of pressurization and prepressurization are investigated. Calculations for finite and infinite liquid volumes are also presented. Gas generation in the bubble is shown to have a significant effect on its evolution and the introduction of a surface enhancement factor leads to a runaway reaction. For the conditions considered, the reacting bubble oscillates at a frequency of about 35 kHz over the first 0.5 milliseconds. This frequency decreases as the surface enhancement factor is increased. The implication is that a one dimensional model of this process may be tractable from the standpoint of computer time.

  20. The effect of expiratory rib cage compression before endotracheal suctioning on the vital signs in patients under mechanical ventilation

    PubMed Central

    Bousarri, Mitra Payami; Shirvani, Yadolah; Agha-Hassan-Kashani, Saeed; Nasab, Nouredin Mousavi

    2014-01-01

    Background: In patients undergoing mechanical ventilation, mucus production and secretion is high as a result of the endotracheal tube. Because endotracheal suction in these patients is essential, chest physiotherapy techniques such as expiratory rib cage compression before endotracheal suctioning can be used as a means to facilitate mobilizing and removing airway secretion and improving alveolar ventilation. As one of the complications of mechanical ventilation and endotracheal suctioning is decrease of cardiac output, this study was carried out to determine the effect of expiratory rib cage compression before endotracheal suctioning on the vital signs in patients under mechanical ventilation. Materials and Methods: This study was a randomized clinical trial with a crossover design. The study subjects included 50 mechanically ventilated patients, hospitalized in intensive care wards of Valiasr and Mousavi hospitals in Zanjan, Iran. Subjects were selected by consecutive sampling and randomly allocated to groups 1 and 2. The patients received endotracheal suctioning with or without rib cage compression, with a minimum of 3 h interval between the two interventions. Expiratory rib cage compression was performed for 5 min before endotracheal suctioning. Vital signs were measured 5 min before and 15 and 25 min after endotracheal suctioning. Data were recorded on a data recording sheet. Data were analyzed using paired t-tests. Results: There were statistically significant differences in the means of vital signs measured 5 min before with 15 and 25 min after endotracheal suctioning with rib cage compression (P < 0. 01). There was no significant difference in the means of diastolic pressure measured 25 min after with baseline in this stage). But on the reverse mode, there was a significant difference between the means of pulse and respiratory rate 15 min after endotracheal suctioning and the baseline values (P < 0.002). This effect continued up to 25 min after endotracheal

  1. Statistical mechanics analysis of thresholding 1-bit compressed sensing

    NASA Astrophysics Data System (ADS)

    Xu, Yingying; Kabashima, Yoshiyuki

    2016-08-01

    The one-bit compressed sensing framework aims to reconstruct a sparse signal by only using the sign information of its linear measurements. To compensate for the loss of scale information, past studies in the area have proposed recovering the signal by imposing an additional constraint on the l 2-norm of the signal. Recently, an alternative strategy that captures scale information by introducing a threshold parameter to the quantization process was advanced. In this paper, we analyze the typical behavior of thresholding 1-bit compressed sensing utilizing the replica method of statistical mechanics, so as to gain an insight for properly setting the threshold value. Our result shows that fixing the threshold at a constant value yields better performance than varying it randomly when the constant is optimally tuned, statistically. Unfortunately, the optimal threshold value depends on the statistical properties of the target signal, which may not be known in advance. In order to handle this inconvenience, we develop a heuristic that adaptively tunes the threshold parameter based on the frequency of positive (or negative) values in the binary outputs. Numerical experiments show that the heuristic exhibits satisfactory performance while incurring low computational cost.

  2. Mechanics of particulate composites with glassy polymer binders in compression

    PubMed Central

    Jordan, J. L.; Spowart, J. E.; Kendall, M. J.; Woodworth, B.; Siviour, C. R.

    2014-01-01

    Whether used as structural components in design or matrix materials for composites, the mechanical properties of polymers are increasingly important. The compressive response of extruded polymethyl methacrylate (PMMA) rod with aligned polymer chains and Al–Ni–PMMA particulate composites are investigated across a range of strain rates and temperatures. The particulate composites were prepared using an injection-moulding technique resulting in highly anisotropic microstructures. The mechanics of these materials are discussed in the light of theories of deformation for glassy polymers. The experimental data from this study are compared with PMMA results from the literature as well as epoxy-based composites with identical particulates. The PMMA exhibited the expected strain rate and temperature dependence and brittle failure was observed at the highest strain rates and lowest temperatures. The Al–Ni–PMMA composites were found to have similar stress–strain response to the PMMA with reduced strain softening after yield. Increasing volume fraction of particulates in the composite resulted in decreased strength. PMID:24711495

  3. Mechanical properties of Indonesian-made narrow dynamic compression plate.

    PubMed

    Dewo, P; van der Houwen, E B; Sharma, P K; Magetsari, R; Bor, T C; Vargas-Llona, L D; van Horn, J R; Busscher, H J; Verkerke, G J

    2012-09-01

    Osteosynthesis plates are clinically used to fixate and position a fractured bone. They should have the ability to withstand cyclic loads produced by muscle contractions and total body weight. The very high demand for osteosynthesis plates in developing countries in general and in Indonesia in particular necessitates the utilisation of local products. In this paper, we investigated the mechanical properties, i.e. proportional limit and fatigue strength of Indonesian-made Narrow Dynamic Compression Plates (Narrow DCP) as one of the most frequently used osteosynthesis plates, in comparison to the European AO standard plate, and its relationship to geometry, micro structural features and surface defects of the plates. All Indonesian-made plates appeared to be weaker than the standard Narrow DCP because they consistently failed at lower stresses. Surface defects did not play a major role in this, although the polishing of the Indonesian Narrow DCP was found to be poor. The standard plate showed indications of cold deformation from the production process in contrast to the Indonesian plates, which might be the first reason for the differences in strength. This is confirmed by hardness measurements. A second reason could be the use of an inferior version of stainless steel. The Indonesian plates showed lower mechanical behaviour compared to the AO-plates. These findings could initiate the development of improved Indonesian manufactured DCP-plates with properties comparable to commonly used plates, such as the standard European AO-plates.

  4. Incorporation of CPR Data into ATD Chest Impact Response Requirements.

    PubMed

    Maltese, Matthew R; Arbogast, Kristy B; Nadkarni, Vinay; Berg, Robert; Balasubramanian, Sriram; Seacrist, Thomas; Kent, Richard W; Parent, Daniel P; Craig, Matthew; Ridella, Stephen A

    2010-01-01

    Pediatric and adult ATD's are key tools for the development of motor vehicle crash safety systems. Previous researchers developed size-based scaling methods to adapt blunt chest impact data from adult post-mortem human subjects (PMHS) for pediatric ATD chests design requirements, using skull or femur elastic modulus ratios to estimate the change in whole chest stiffness during maturation. Recently, the mechanics of chest compression during cardiopulmonary resuscitation (CPR) of patients spanning the pediatric and elderly ages have been reported. Our objective was to integrate these pediatric and adult chest stiffness data from CPR into the established scaling methods to 1) compare new CPR-based and existing pediatric ATD chest biofidelity response requirements and 2) develop new CPR-based corridors for ages 12 and 20 years, which do not currently exist. Compared to the current 6-year-old ATD corridor, the maximum force of the CPR-based 6-year-old corridor was 7% less and the maximum displacement was 8% greater, indicating a softer chest. Compared to the current 10-year-old corridor, the new 10-year-old corridor peak force was 12% higher and the peak displacement was 11% smaller, suggesting a stiffer chest. The 12-year-old corridor developed in this paper was 10% higher in maximum force and 4% lower in maximum displacement compared with the adult 5(th) percentile female (AF05). Finally, the 20-year-old 50(th) percentile male (AM50(20)) corridor was 24% higher in maximum force and 19% lower in maximum displacement than 63-year old 50(th) percentile adult male (AM50(63)) corridor, suggesting a stiffer chest. We consider all the new corridors preliminary, as data collection is ongoing for CPR subjects under age 8 years and in the young and middle adult age ranges.

  5. Incorporation of CPR Data into ATD Chest Impact Response Requirements

    PubMed Central

    Maltese, Matthew R.; Arbogast, Kristy B.; Nadkarni, Vinay; Berg, Robert; Balasubramanian, Sriram; Seacrist, Thomas; Kent, Richard W.; Parent, Daniel P.; Craig, Matthew; Ridella, Stephen A.

    2010-01-01

    Pediatric and adult ATD’s are key tools for the development of motor vehicle crash safety systems. Previous researchers developed size-based scaling methods to adapt blunt chest impact data from adult post-mortem human subjects (PMHS) for pediatric ATD chests design requirements, using skull or femur elastic modulus ratios to estimate the change in whole chest stiffness during maturation. Recently, the mechanics of chest compression during cardiopulmonary resuscitation (CPR) of patients spanning the pediatric and elderly ages have been reported. Our objective was to integrate these pediatric and adult chest stiffness data from CPR into the established scaling methods to 1) compare new CPR-based and existing pediatric ATD chest biofidelity response requirements and 2) develop new CPR-based corridors for ages 12 and 20 years, which do not currently exist. Compared to the current 6-year-old ATD corridor, the maximum force of the CPR-based 6-year-old corridor was 7% less and the maximum displacement was 8% greater, indicating a softer chest. Compared to the current 10-year-old corridor, the new 10-year-old corridor peak force was 12% higher and the peak displacement was 11% smaller, suggesting a stiffer chest. The 12-year-old corridor developed in this paper was 10% higher in maximum force and 4% lower in maximum displacement compared with the adult 5th percentile female (AF05). Finally, the 20-year-old 50th percentile male (AM5020) corridor was 24% higher in maximum force and 19% lower in maximum displacement than 63-year old 50th percentile adult male (AM5063) corridor, suggesting a stiffer chest. We consider all the new corridors preliminary, as data collection is ongoing for CPR subjects under age 8 years and in the young and middle adult age ranges. PMID:21050593

  6. Chest Imaging.

    PubMed

    Keijsers, Ruth G; Veltkamp, Marcel; Grutters, Jan C

    2015-12-01

    Chest imaging has a central role in the diagnosis and monitoring of sarcoidosis. For staging of pulmonary disease on chest radiograph, Scadding stages are still widely used. High-resolution CT (HRCT), however, is more accurate in visualizing the various manifestations of pulmonary sarcoidosis as well its complications. A generally accepted HRCT scoring system is lacking. Fluorodeoxyglucose F 18 positron emission tomography can visualize disease activity better than conventional makers in a significant proportion of patients. In patients with extensive changes on HRCT but no parenchymal fluorodeoxyglucose F 18 uptake, prudence with regard to initiation or intensification of immunosuppressive treatment is warranted. PMID:26593136

  7. Impacts to the chest of PMHSs - Influence of impact location and load distribution on chest response.

    PubMed

    Holmqvist, Kristian; Svensson, Mats Y; Davidsson, Johan; Gutsche, Andreas; Tomasch, Ernst; Darok, Mario; Ravnik, Dean

    2016-02-01

    The chest response of the human body has been studied for several load conditions, but is not well known in the case of steering wheel rim-to-chest impact in heavy goods vehicle frontal collisions. The aim of this study was to determine the response of the human chest in a set of simulated steering wheel impacts. PMHS tests were carried out and analysed. The steering wheel load pattern was represented by a rigid pendulum with a straight bar-shaped front. A crash test dummy chest calibration pendulum was utilised for comparison. In this study, a set of rigid bar impacts were directed at various heights of the chest, spanning approximately 120mm around the fourth intercostal space. The impact energy was set below a level estimated to cause rib fracture. The analysed results consist of responses, evaluated with respect to differences in the impacting shape and impact heights on compression and viscous criteria chest injury responses. The results showed that the bar impacts consistently produced lesser scaled chest compressions than the hub; the Middle bar responses were around 90% of the hub responses. A superior bar impact provided lesser chest compression; the average response was 86% of the Middle bar response. For inferior bar impacts, the chest compression response was 116% of the chest compression in the middle. The damping properties of the chest caused the compression to decrease in the high speed bar impacts to 88% of that in low speed impacts. From the analysis it could be concluded that the bar impact shape provides lower chest criteria responses compared to the hub. Further, the bar responses are dependent on the impact location of the chest. Inertial and viscous effects of the upper body affect the responses. The results can be used to assess the responses of human substitutes such as anthropomorphic test devices and finite element human body models, which will benefit the development process of heavy goods vehicle safety systems.

  8. Impacts to the chest of PMHSs - Influence of impact location and load distribution on chest response.

    PubMed

    Holmqvist, Kristian; Svensson, Mats Y; Davidsson, Johan; Gutsche, Andreas; Tomasch, Ernst; Darok, Mario; Ravnik, Dean

    2016-02-01

    The chest response of the human body has been studied for several load conditions, but is not well known in the case of steering wheel rim-to-chest impact in heavy goods vehicle frontal collisions. The aim of this study was to determine the response of the human chest in a set of simulated steering wheel impacts. PMHS tests were carried out and analysed. The steering wheel load pattern was represented by a rigid pendulum with a straight bar-shaped front. A crash test dummy chest calibration pendulum was utilised for comparison. In this study, a set of rigid bar impacts were directed at various heights of the chest, spanning approximately 120mm around the fourth intercostal space. The impact energy was set below a level estimated to cause rib fracture. The analysed results consist of responses, evaluated with respect to differences in the impacting shape and impact heights on compression and viscous criteria chest injury responses. The results showed that the bar impacts consistently produced lesser scaled chest compressions than the hub; the Middle bar responses were around 90% of the hub responses. A superior bar impact provided lesser chest compression; the average response was 86% of the Middle bar response. For inferior bar impacts, the chest compression response was 116% of the chest compression in the middle. The damping properties of the chest caused the compression to decrease in the high speed bar impacts to 88% of that in low speed impacts. From the analysis it could be concluded that the bar impact shape provides lower chest criteria responses compared to the hub. Further, the bar responses are dependent on the impact location of the chest. Inertial and viscous effects of the upper body affect the responses. The results can be used to assess the responses of human substitutes such as anthropomorphic test devices and finite element human body models, which will benefit the development process of heavy goods vehicle safety systems. PMID:26687541

  9. A non-topological mechanism for negative linear compressibility.

    PubMed

    Binns, Jack; Kamenev, Konstantin V; Marriott, Katie E R; McIntyre, Garry J; Moggach, Stephen A; Murrie, Mark; Parsons, Simon

    2016-06-14

    Negative linear compressibility (NLC), the increase in a unit cell length with pressure, is a rare phenomenon in which hydrostatic compression of a structure promotes expansion along one dimension. It is usually a consequence of crystal structure topology. We show that the source of NLC in the Co(ii) citrate metal-organic framework UTSA-16 lies not in framework topology, but in the relative torsional flexibility of Co(ii)-centred tetrahedra compared to more rigid octahedra. PMID:27203683

  10. A non-topological mechanism for negative linear compressibility.

    PubMed

    Binns, Jack; Kamenev, Konstantin V; Marriott, Katie E R; McIntyre, Garry J; Moggach, Stephen A; Murrie, Mark; Parsons, Simon

    2016-06-14

    Negative linear compressibility (NLC), the increase in a unit cell length with pressure, is a rare phenomenon in which hydrostatic compression of a structure promotes expansion along one dimension. It is usually a consequence of crystal structure topology. We show that the source of NLC in the Co(ii) citrate metal-organic framework UTSA-16 lies not in framework topology, but in the relative torsional flexibility of Co(ii)-centred tetrahedra compared to more rigid octahedra.

  11. Chest pain

    MedlinePlus

    ... provider may ask questions such as: Is the pain between the shoulder blades? Under the breast bone? Does the pain ... How long does the pain last? Does the pain go from your chest into your shoulder, arm, neck, jaw, or back? Is the pain ...

  12. Lung function tests in neonates and infants with chronic lung disease: lung and chest-wall mechanics.

    PubMed

    Gappa, Monika; Pillow, J Jane; Allen, Julian; Mayer, Oscar; Stocks, Janet

    2006-04-01

    This is the fifth paper in a review series that summarizes available data and critically discusses the potential role of lung function testing in infants and young children with acute neonatal respiratory disorders and chronic lung disease of infancy (CLDI). This review focuses on respiratory mechanics, including chest-wall and tissue mechanics, obtained in the intensive care setting and in infants during unassisted breathing. Following orientation of the reader to the subject area, we focused comments on areas of enquiry proposed in the introductory paper to this series. The quality of the published literature is reviewed critically with respect to relevant methods, equipment and study design, limitations and strengths of different techniques, and availability and appropriateness of reference data. Recommendations to guide future investigations in this field are provided. Numerous different methods have been used to assess respiratory mechanics with the aims of describing pulmonary status in preterm infants and assessing the effect of therapeutic interventions such as surfactant treatment, antenatal or postnatal steroids, or bronchodilator treatment. Interpretation of many of these studies is limited because lung volume was not measured simultaneously. In addition, populations are not comparable, and the number of infants studied has generally been small. Nevertheless, results appear to support the pathophysiological concept that immaturity of the lung leads to impaired lung function, which may improve with growth and development, irrespective of the diagnosis of chronic lung disease. To fully understand the impact of immaturity on the developing lung, it is unlikely that a single parameter such as respiratory compliance or resistance will accurately describe underlying changes. Assessment of respiratory mechanics will have to be supplemented by assessment of lung volume and airway function. New methods such as the low-frequency forced oscillation technique, which

  13. A method for intermediate strain rate compression testing and study of compressive failure mechanism of Mg-Al-Zn alloy

    NASA Astrophysics Data System (ADS)

    Gupta, Nikhil; Luong, Dung D.; Rohatgi, Pradeep K.

    2011-05-01

    Obtaining meaningful information from the test results is a challenge in the split-Hopkinson pressure bar (SHPB) test method if the specimen does not fail during the test. Although SHPB method is now widely used for high strain rate testing, this limitation has made it difficult to use it for characterization of materials in the intermediate strain rate range (typically 10-1000 s-1). In the present work, a method is developed to characterize materials in the intermediate strain rate range using SHPB setup. In this method, the specimen is repeatedly tested under compression at a given strain rate until failure is achieved. The stress-strain graphs obtained from each test cycle are used to plot the master stress-strain graph for that strain rate. This method is used to study the strain rate dependence of compressive response of a Mg-Al-Zn alloy in the intermediate strain rate range. A remarkable difference is observed in the failure mechanism of the alloy under quasi-static and intermediate strain rate compression. Matrix cracking is the main failure mechanism under quasi-static compression, whereas shattering of intermetallic precipitates, along with plastic deformation of the matrix, is discovered to become prominent as the strain rate is increased.

  14. Encyclopedia of fluid mechanics. Volume 8 - Aerodynamics and compressible flows

    NASA Astrophysics Data System (ADS)

    Cheremisinoff, Nicholas P.

    Advanced analytical methods for compressible flows and their application to specific engineering problems are discussed in chapters by leading experts. Topics addressed include fluid viscosity, laminar flow past semiinfinite bodies, the structure of turbulent boundary layers, homogeneous turbulence, turbulent shear flows and jets, vortex patterns on slender bodies, wake interference and vortex shedding, turbulent rough-wall skin friction and heat transfer, FEM iterative solutions of compressible flows, transient natural-convection flows, and direct-contact transfer processes with moving liquid droplets. Consideration is given to artificially thickening turbulent boundary layers, subsonic transitory stalled flows in diffusers, impeller-blade design for centrifugal and axial blowers, transonic cascade flows, high-speed turboprop noise, turbine-blade vibrations, compressible flow in valves, the performance of cryogenic pumps, the structure of turbulent dense-spray jets, and the dynamics of wind machines.

  15. Chest X-Ray

    MedlinePlus

    ... by: Image/Video Gallery Your radiologist explains chest x-ray. Transcript Welcome to Radiology Info dot org! Hello, ... you about chest radiography also known as chest x-rays. Chest x-rays are the most commonly performed ...

  16. Automatic compression adjusting mechanism for internal combustion engines

    NASA Technical Reports Server (NTRS)

    Akkerman, J. W. (Inventor)

    1983-01-01

    Means for controlling the compression pressure in an internal combustion engine having one or more cylinders and subject to widely varying power output requirements are provided. Received between each crank pin and connecting rod is an eccentric sleeve selectively capable of rotation about the crank pin and/or inside the rod and for latching with the rod to vary the effective length of the connecting rod and thereby the clearance volume of the engine. The eccentric normally rotates inside the connecting rod during the exhaust and intake strokes but a latching pawl carried by the eccentric is movable radially outwardly to latch the rod and eccentric together during the compression and power strokes. A control valve responds to intake manifold pressure to time the supply of hydraulic fluid to move the latch-pawl outwardly, varying the effective rod length to maintain a substantially optimum firing chamber pressure at all intake manifold pressures.

  17. The compression mechanism of garnets based on in situ observations

    NASA Astrophysics Data System (ADS)

    Dymshits, Anna; Sharygin, Igor; Litasov, Konstantin; Shatskiy, Anton

    2014-05-01

    Previously it was showed that the bulk modulus of garnet is strongly affected by the bulk modulus of the dodecahedra, while compressibility of other individual polyhedra displays no correlation with the compressibility of the structure as a whole (Milman et al., 2001). If so, Na-majorite (Na-maj) would have the smallest bulk modulus of all silicate garnets, as a phase with a predicted dodecahedral bulk modulus of approximately 70 GPa (Hazen et al., 1994). In fact Na-maj has the largest bulk modulus among the silicate garnets. This behavior must reflect the all-mineral framework of Na-maj with very small cell volume and silicon in the octahedral position. Thus, we conclude that not only the dodecahedral sites, but also the behavior of the garnet framework and relative sizes of the 8- and 6-coordinated cations, control garnet compression. The octahedral site in Na-maj is quite small (1.79 Å) and contains only silicon in comparison to the pyrope (1.85 Å) or majorite (1.88 Å). The small and highly charged octahedra shares four edges with the dodecahedra and thus restrict the volume of the large and low charged dodecahedra. In spite Na-maj has a large average X-cation radius (RNa = 1.07 Å) its dodecahedral volume is relatively small (V = 21.23 and 21.26 Å3). Pacalo et al. (1992) suggested that XO8 polyhedra act as braces and controls the amount of rotation between tetrahedra and octahedra within the corner-linked chains. In case of pyrope XO8 cite is not filled up and polyhedra within the corner-linked chains can rotate freely to accommodate applied stress. In case of Na-maj the dodecahedral site is filled up and rotational freedom is minimized. The dodecahedral site in knorringite (Knr) contains cation with a small radius (Mg-O = 2.22 and 2.34 Å), so XO8 polyhedra is not filled up and can rotate freely to accommodate applied stress. In case of uvarovite not only octahedral but the dodecahedral site is also large (Ca-O = 2.35 and 2.51 Å), so the rotational

  18. Structural basis for the nonlinear mechanics of fibrin networks under compression.

    PubMed

    Kim, Oleg V; Litvinov, Rustem I; Weisel, John W; Alber, Mark S

    2014-08-01

    Fibrin is a protein polymer that forms a 3D filamentous network, a major structural component of protective physiological blood clots as well as life threatening pathological thrombi. It plays an important role in wound healing, tissue regeneration and is widely employed in surgery as a sealant and in tissue engineering as a scaffold. The goal of this study was to establish correlations between structural changes and mechanical responses of fibrin networks exposed to compressive loads. Rheological measurements revealed nonlinear changes of fibrin network viscoelastic properties under dynamic compression, resulting in network softening followed by its dramatic hardening. Repeated compression/decompression enhanced fibrin clot stiffening. Combining fibrin network rheology with simultaneous confocal microscopy provided direct evidence of structural modulations underlying nonlinear viscoelasticity of compressed fibrin networks. Fibrin clot softening in response to compression strongly correlated with fiber buckling and bending, while hardening was associated with fibrin network densification. Our results suggest a complex interplay of entropic and enthalpic mechanisms accompanying structural changes and accounting for the nonlinear mechanical response in fibrin networks undergoing compressive deformations. These findings provide new insight into the fibrin clot structural mechanics and can be useful for designing fibrin-based biomaterials with modulated viscoelastic properties.

  19. Structural basis for the nonlinear mechanics of fibrin networks under compression.

    PubMed

    Kim, Oleg V; Litvinov, Rustem I; Weisel, John W; Alber, Mark S

    2014-08-01

    Fibrin is a protein polymer that forms a 3D filamentous network, a major structural component of protective physiological blood clots as well as life threatening pathological thrombi. It plays an important role in wound healing, tissue regeneration and is widely employed in surgery as a sealant and in tissue engineering as a scaffold. The goal of this study was to establish correlations between structural changes and mechanical responses of fibrin networks exposed to compressive loads. Rheological measurements revealed nonlinear changes of fibrin network viscoelastic properties under dynamic compression, resulting in network softening followed by its dramatic hardening. Repeated compression/decompression enhanced fibrin clot stiffening. Combining fibrin network rheology with simultaneous confocal microscopy provided direct evidence of structural modulations underlying nonlinear viscoelasticity of compressed fibrin networks. Fibrin clot softening in response to compression strongly correlated with fiber buckling and bending, while hardening was associated with fibrin network densification. Our results suggest a complex interplay of entropic and enthalpic mechanisms accompanying structural changes and accounting for the nonlinear mechanical response in fibrin networks undergoing compressive deformations. These findings provide new insight into the fibrin clot structural mechanics and can be useful for designing fibrin-based biomaterials with modulated viscoelastic properties. PMID:24840618

  20. Structural basis for the nonlinear mechanics of fibrin networks under compression

    PubMed Central

    Kim, Oleg V.; Litvinov, Rustem I.; Weisel, John W.; Alber, Mark S.

    2014-01-01

    Fibrin is a protein polymer that forms a 3D filamentous network, a major structural component of protective physiological blood clots as well as life threatening pathological thrombi. It plays an important role in wound healing, tissue regeneration and is widely employed in surgery as a sealant and in tissue engineering as a scaffold. The goal of this study was to establish correlations between structural changes and mechanical responses of fibrin networks exposed to compressive loads. Rheological measurements revealed nonlinear changes of fibrin network viscoelastic properties under dynamic compression, resulting in network softening followed by its dramatic hardening. Repeated compression/decompression enhanced fibrin clot stiffening. Combining fibrin network rheology with simultaneous confocal microscopy provided direct evidence of structural modulations underlying nonlinear viscoelasticity of compressed fibrin networks. Fibrin clot softening in response to compression strongly correlated with fiber buckling and bending, while hardening was associated with fibrin network densification. Our results suggest a complex interplay of entropic and enthalpic mechanisms accompanying structural changes and accounting for the nonlinear mechanical response in fibrin networks undergoing compressive deformations. These findings provide new insight into the fibrin clot structural mechanics and can be useful for designing fibrin-based biomaterials with modulated viscoelastic properties. PMID:24840618

  1. Joining mechanism with stem tension and interlocked compression ring

    DOEpatents

    James, Allister W.; Morrison, Jay A.

    2012-09-04

    A stem (34) extends from a second part (30) through a hole (28) in a first part (22). A groove (38) around the stem provides a non-threaded contact surface (42) for a ring element (44) around the stem. The ring element exerts an inward force against the non-threaded contact surface at an angle that creates axial tension (T) in the stem, pulling the second part against the first part. The ring element is formed of a material that shrinks relative to the stem by sintering. The ring element may include a split collet (44C) that fits partly into the groove, and a compression ring (44E) around the collet. The non-threaded contact surface and a mating distal surface (48) of the ring element may have conic geometries (64). After shrinkage, the ring element is locked onto the stem.

  2. Effects of the mechanical energy of multi-tableting compression on the polymorphic transformations of chlorpropamide.

    PubMed

    Otsuka, M; Matsumoto, T; Kaneniwa, N

    1989-10-01

    The effects of the mechanical energy of tableting compression on the polymorphic transformation of chlorpropamide have been examined. A single-punch eccentric tableting machine with a load cell and a non-contact displacement transducer were used to measure compression stress, distance and energy. An amount of 100 mg of the stable form A or the meta-stable form C of the drug was loaded into the press and the sample compressed with a compression stress of 196 MPa at room temperature (20 degrees C). The compression cycle was repeated from 1 to 30 times. The powder X-ray diffraction profiles of the deagglomerated compressed sample powder were measured to calculate the polymorphic content. The results on forms A and C suggested that both forms were transformed into each other in the solid state by mechanical energy during tableting. The contents of forms A and C reached equilibrium at a constant value above 100 J g-1 of compression energy after more than 10 cycles. After 30 tableting cycles of forms A and C, the contents of A, C and the non-crystalline solid were almost constant at about 45, 25 and 30%, respectively. The compression energies were estimated to be about 500-600 J g-1. From the results it seems that the transformation mechanism of forms A and C during tableting were as follows. The crystal form of A or C was converted to a non-crystalline solid by the mechanical energy, and the solid was then transformed into form A or C. PMID:2575141

  3. Chest radiation - discharge

    MedlinePlus

    Radiation - chest - discharge; Cancer - chest radiation; Lymphoma - chest radiation ... When you have radiation treatment for cancer, your body goes through changes. About 2 weeks after your first treatment: It may be hard ...

  4. Chest tube insertion

    MedlinePlus

    Chest drainage tube insertion; Insertion of tube into chest; Tube thoracostomy; Pericardial drain ... When your chest tube is inserted, you will lie on your side or sit partly upright, with one arm over your head. Sometimes, ...

  5. Optimization of the dye-sensitized solar cell performance by mechanical compression

    PubMed Central

    2014-01-01

    In this study, the P25 titanium dioxide (TiO2) nanoparticle (NP) thin film was coated on the fluorine-doped tin oxide (FTO) glass substrate by a doctor blade method. The film then compressed mechanically to be the photoanode of dye-sensitized solar cells (DSSCs). Various compression pressures on TiO2 NP film were tested to optimize the performance of DSSCs. The mechanical compression reduces TiO2 inter-particle distance improving the electron transport efficiency. The UV–vis spectrophotometer and electrochemical impedance spectroscopy (EIS) were employed to quantify the light-harvesting efficiency and the charge transport impedance at various interfaces in DSSC, respectively. The incident photon-to-current conversion efficiency was also monitored. The results show that when the DSSC fabricated by the TiO2 NP thin film compressed at pressure of 279 kg/cm2, the minimum resistance of 9.38 Ω at dye/TiO2 NP/electrolyte interfaces, the maximum short-circuit photocurrent density of 15.11 mA/cm2, and the photoelectric conversion efficiency of 5.94% were observed. Compared to the DSSC fabricated by the non-compression of TiO2 NP thin film, the overall conversion efficiency is improved over 19.5%. The study proves that under suitable compression pressure the performance of DSSC can be optimized. PMID:25276109

  6. Boron Nitride Coated Carbon Nanotube Arrays with Enhanced Compressive Mechanical Property

    NASA Astrophysics Data System (ADS)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Tan, Dunlin; Zhang, Bowei; Tok, Alfred Iing Yoong; Teo, Edwin Hang Tong

    Vertically aligned carbon nanotube (CNT) array is one of the most promising energy dissipating materials due to its excellent temperature invariant mechanical property. However, the CNT arrays with desirable recoverability after compression is still a challenge. Here, we report on the mechanical enhancement of the CNT arrays reinforced by coating with boron nitride (BN) layers. These BN coated CNT (BN/CNT) arrays exhibit excellent compressive strength and recoverability as compared to those of the as-prepared CNT arrays which totally collapsed after compression. In addition, the BN coating also provides better resistance to oxidation due to its intrinsic thermal stability. This work presented here opens a new pathway towards tuning mechanical behavior of any arbitrary CNT arrays for promising potential such as damper, vibration isolator and shock absorber applications.

  7. Simulated effect on the compressive and shear mechanical properties of bionic integrated honeycomb plates.

    PubMed

    He, Chenglin; Chen, Jinxiang; Wu, Zhishen; Xie, Juan; Zu, Qiao; Lu, Yun

    2015-05-01

    Honeycomb plates can be applied in many fields, including furniture manufacturing, mechanical engineering, civil engineering, transportation and aerospace. In the present study, we discuss the simulated effect on the mechanical properties of bionic integrated honeycomb plates by investigating the compressive and shear failure modes and the mechanical properties of trabeculae reinforced by long or short fibers. The results indicate that the simulated effect represents approximately 80% and 70% of the compressive and shear strengths, respectively. Compared with existing bionic samples, the mass-specific strength was significantly improved. Therefore, this integrated honeycomb technology remains the most effective method for the trial manufacturing of bionic integrated honeycomb plates. The simulated effect of the compressive rigidity is approximately 85%. The short-fiber trabeculae have an advantage over the long-fiber trabeculae in terms of shear rigidity, which provides new evidence for the application of integrated bionic honeycomb plates.

  8. Simulated effect on the compressive and shear mechanical properties of bionic integrated honeycomb plates.

    PubMed

    He, Chenglin; Chen, Jinxiang; Wu, Zhishen; Xie, Juan; Zu, Qiao; Lu, Yun

    2015-05-01

    Honeycomb plates can be applied in many fields, including furniture manufacturing, mechanical engineering, civil engineering, transportation and aerospace. In the present study, we discuss the simulated effect on the mechanical properties of bionic integrated honeycomb plates by investigating the compressive and shear failure modes and the mechanical properties of trabeculae reinforced by long or short fibers. The results indicate that the simulated effect represents approximately 80% and 70% of the compressive and shear strengths, respectively. Compared with existing bionic samples, the mass-specific strength was significantly improved. Therefore, this integrated honeycomb technology remains the most effective method for the trial manufacturing of bionic integrated honeycomb plates. The simulated effect of the compressive rigidity is approximately 85%. The short-fiber trabeculae have an advantage over the long-fiber trabeculae in terms of shear rigidity, which provides new evidence for the application of integrated bionic honeycomb plates. PMID:25746272

  9. CT angiography - chest

    MedlinePlus

    Computed tomography angiography - thorax; CTA - lungs; Pulmonary embolism - CTA chest; Thoracic aortic aneurysm - CTA chest; Venous thromboembolism - CTA lung; Blood clot - CTA lung; Embolus - CTA lung; CT ...

  10. Integrated random-aligned carbon nanotube layers: deformation mechanism under compression

    NASA Astrophysics Data System (ADS)

    Zeng, Zhiping; Gui, Xuchun; Gan, Qiming; Lin, Zhiqiang; Zhu, Yuan; Zhang, Wenhui; Xiang, Rong; Cao, Anyuan; Tang, Zikang

    2014-01-01

    Carbon nanotubes have the potential to construct highly compressible and elastic macroscopic structures such as films, aerogels and sponges. The structure-related deformation mechanism determines the mechanical behavior of those structures and niche applications. Here, we show a novel strategy to integrate aligned and random nanotube layers and reveal their deformation mechanism under uniaxial compression with a large range of strain and cyclic testing. Integrated nanotube layers deform sequentially with different mechanisms due to the distinct morphology of each layer. While the aligned layer forms buckles under compression, nanotubes in the random layer tend to be parallel and form bundles, resulting in the integration of quite different properties (strength and stiffness) and correspondingly distinct plateau regions in the stress-strain curves. Our results indicate a great promise of constructing hierarchical carbon nanotube structures with tailored energy absorption properties, for applications such as cushioning and buffering layers in microelectromechanical systems.Carbon nanotubes have the potential to construct highly compressible and elastic macroscopic structures such as films, aerogels and sponges. The structure-related deformation mechanism determines the mechanical behavior of those structures and niche applications. Here, we show a novel strategy to integrate aligned and random nanotube layers and reveal their deformation mechanism under uniaxial compression with a large range of strain and cyclic testing. Integrated nanotube layers deform sequentially with different mechanisms due to the distinct morphology of each layer. While the aligned layer forms buckles under compression, nanotubes in the random layer tend to be parallel and form bundles, resulting in the integration of quite different properties (strength and stiffness) and correspondingly distinct plateau regions in the stress-strain curves. Our results indicate a great promise of

  11. Inelastic deformation mechanisms in SCS-6/Ti 15-3 MMC lamina under compression

    NASA Technical Reports Server (NTRS)

    Newaz, Golam M.; Majumdar, Bhaskar S.

    1993-01-01

    An investigation was undertaken to study the inelastic deformation mechanisms in (0)(sub 8) and (90)(sub 8) Ti 15-3/SCS-6 lamina subjected to pure compression. Monotonic tests were conducted at room temperature (RT), 538 C and 650 C. Results indicate that mechanical response and deformation characteristics were different in monotonic tension and compression loading whereas some of those differences could be attributed to residual stress effects. There were other differences because of changes in damage and failure modes. The inelastic deformation in the (0)(sub 8) lamina under compression was controlled primarily by matrix plasticity, although some evidence of fiber-matrix debonding was observed. Failure of the specimen in compression was due to fiber buckling in a macroscopic shear zone (the failure plane). The inelastic deformation mechanisms under compression in (90)(sub 8) lamina were controlled by radial fiber fracture, matrix plasticity, and fiber-matrix debonding. The radial fiber fracture was a new damage mode observed for MMC's. Constitutive response was predicted for both the (0)(sub 8) and (90)(sub 8) laminae, using AGLPLY, METCAN, and Battelle's Unit Cell FEA model. Results from the analyses were encouraging.

  12. Emergency Chest Imaging.

    PubMed

    Havrda, Jonathan B

    2015-01-01

    This article presents the anatomy of the chest, heart, and upper airway and describes types of traumatic pathology and injuries of the chest. Chest imaging in a variety of settings is described. Radiography, computed tomography, and ultrasonography are discussed, along with the benefits and limitations of each modality. Finally, promising technological developments that could aid chest imaging in emergent situations are reviewed.

  13. Analyzing stability of compressible, swirling pipe flows using disturbance energy mechanisms

    NASA Astrophysics Data System (ADS)

    Samanta, Arnab

    2015-11-01

    We investigate the spatial stability of compressible, viscous pipe flows with radius-dependent mean density profiles, subjected to solid body rotations. Holding the flow Reynolds number fixed, as the Rossby number is lowered (increased swirl), flow usually transitions from being stable to convectively unstable, finally leading to absolute instability. In this work, the role of compressibility on flow stability is characterized via specifying stratified mean densities where for certain choices the flow appears to be unconditionally stable while for others the situation is more complex with an initially convectively unstable state becoming stable as rotational speeds are progressively raised. A disturbance energy-based method is used to obtain physical understanding of the instability mechanisms in such flows with special emphasis on the role of compressibility. We observe that mechanisms due to pressure energy redistribution and entropy perturbations dominate as primary instability mechanisms instead of the energy due to shear in axial velocity, the primary source of instability in incompressible flows. With reference to pipe flows, we quantify the complex interplay between the various energy mechanisms to provide physical insight into the stability of compressible swirling flows.

  14. A variational principle for compressible fluid mechanics: Discussion of the multi-dimensional theory

    NASA Technical Reports Server (NTRS)

    Prozan, R. J.

    1982-01-01

    The variational principle for compressible fluid mechanics previously introduced is extended to two dimensional flow. The analysis is stable, exactly conservative, adaptable to coarse or fine grids, and very fast. Solutions for two dimensional problems are included. The excellent behavior and results lend further credence to the variational concept and its applicability to the numerical analysis of complex flow fields.

  15. Thermal and mechanical properties of compression-molded pMDI-reinforced PCL/gluten composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polycaprolactone (PCL) and vital wheat gluten or wheat flour composites were prepared and compatibilized with polymeric diphenylmethane diisocyanate (pMDI) by blending and compression-molding. The thermo-mechanical properties of the composites were determined by thermogravimetric analysis (TGA), di...

  16. Baseline Position Shifts and Mechanical Compression in the Apical Turns of the Cochlea

    NASA Astrophysics Data System (ADS)

    Cooper, N. P.; Dong, W.

    2003-02-01

    Sound-evoked mechanical responses in the apical turns of healthy cochleae are shown to involve both compressive nonlinearity (i.e. growth rates of less than 1dB/dB) and baseline position shifts (i.e. quasi-static displacements). However, at least in the guinea-pig, the frequency and intensity dependencies of the two phenomena differ considerably. A direct link between baseline position shifts and compression can therefore be ruled out. Modelling studies show that the two phenomena could be separate manifestations of a single underlying nonlinearity, but neither one appears to be entirely `responsible' for the other.

  17. Compressive epitactic layers on single-crystal components for improved mechanical durability and strength

    SciTech Connect

    Marion, J.E.; Gualtieri, D.M.; Morris, R.C.

    1987-09-01

    Compressive epitactic layers grown on single-crystal substrates are shown to substantially improve mechanical durability. In this study, neodymium-substituted gadolinium gallium garnet (GGG) layers are grown on undoped GGG substrates. The layers are found to dramatically improve the abrasion resistance of the substrates, but to have only a slight effect on strength. Abrasion treatments, which cause up to 20 times decrease in the strength of substrates without epitactic layers, do not cause a significant decrease in the strength of substrates with these compressive surface layers. This permits the high strength of specially prepared strong substrates to be retained after abrasion.

  18. Mechanical and optical response of diamond crystals shock compressed along different orientations

    NASA Astrophysics Data System (ADS)

    Lang, John Michael, Jr.

    To determine the mechanical and optical response of diamond crystals at high stresses and to evaluate anisotropy effects, single crystals (Type IIa) were shock compressed along the [100], [110], and [111] orientations to ~120 GPa peak elastic stresses. Particle velocity histories and shock velocities, measured using laser interferometry, were used to examine nonlinear elasticity, refractive indices, and Hugoniot elastic limits of shocked diamond. Time-resolved Raman spectroscopy was used to measure the shock compression induced frequency shifts of the triply degenerate 1332.5 cm-1 Raman line. Longitudinal stress-density states for elastic compression along different orientations were determined from the measured particle velocity histories and elastic shock wave velocities. The complete set of third-order elastic constants was determined from the stress-density states and published acoustic data. Several of these constants differed significantly from those calculated using theoretical models. The refractive index of diamond shocked along [100] and [111] was determined from changes in the optical path length along the direction of uniaxial strain. Linear photoelasticity theory predicted the measured refractive index along [111]. In contrast, the refractive index along [100] was nonlinear. The refractive indices for [110] compression were not determined, but the data showed evidence of birefringence. The splitting and frequency shifts of the diamond Raman line were measured for shock compression along [111] and were in good agreement with predictions from prior shock work. Frequency shifts were also measured along [100] and [110] up to ~60 GPa, extending previous measurements. The anharmonic force constants determined from all shock compression measurements agree with the previous shock compression determinations. Hugoniot elastic limits for diamond shock compressed along different orientations were determined from the measured wave profiles. The elastic limits for

  19. Coaxial carbon@boron nitride nanotube arrays with enhanced thermal stability and compressive mechanical properties.

    PubMed

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Huang, Jingfeng; Tan, Dunlin; Zhang, Bowei; Teo, Edwin Hang Tong; Tok, Alfred Iing Yoong

    2016-06-01

    Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability. CNT arrays are grown using a commercially available thermal chemical vapor deposition (TCVD) technique and an outer BNNT with a wall thickness up to 1.37 nm is introduced by a post-growth TCVD treatment. Importantly, compared to the as-grown CNT arrays which deform almost plastically upon compression, the coaxial C@BNNT arrays exhibit an impressive ∼4-fold increase in compressive strength with nearly full recovery after the first compression cycle at a 50% strain (76% recovery maintained after 10 cycles), as well as a significantly high and persistent energy dissipation ratio (∼60% at a 50% strain after 100 cycles), attributed to the synergistic effect between the CNT and outer BNNT. Additionally, the as-prepared C@BNNT arrays show an improved structural stability in air at elevated temperatures, attributing to the outstanding thermal stability of the outer BNNT. This work provides new insights into tailoring the mechanical and thermal behaviours of arbitrary CNT arrays which enables a broader range of applications. PMID:27227818

  20. Suppression mechanism of Kelvin-Helmholtz instability in compressible fluid flows.

    PubMed

    Karimi, Mona; Girimaji, Sharath S

    2016-04-01

    The transformative influence of compressibility on the Kelvin-Helmholtz instability (KHI) at the interface between two fluid streams of different velocities is explicated. When the velocity difference is small (subsonic), shear effects dominate the interface flow dynamics causing monotonic roll-up of vorticity and mixing between the two streams leading to the KHI. We find that at supersonic speed differentials, compressibility forces the dominance of dilatational (acoustic) rather than shear dynamics at the interface. Within this dilatational interface layer, traveling pressure waves cause the velocity perturbations to become oscillatory. We demonstrate that the oscillatory fluid motion reverses vortex roll-up and segregates the two streams leading to KHI suppression. Analysis and illustrations of the compressibility-induced suppression mechanism are presented. PMID:27176246

  1. Suppression mechanism of Kelvin-Helmholtz instability in compressible fluid flows

    NASA Astrophysics Data System (ADS)

    Karimi, Mona; Girimaji, Sharath S.

    2016-04-01

    The transformative influence of compressibility on the Kelvin-Helmholtz instability (KHI) at the interface between two fluid streams of different velocities is explicated. When the velocity difference is small (subsonic), shear effects dominate the interface flow dynamics causing monotonic roll-up of vorticity and mixing between the two streams leading to the KHI. We find that at supersonic speed differentials, compressibility forces the dominance of dilatational (acoustic) rather than shear dynamics at the interface. Within this dilatational interface layer, traveling pressure waves cause the velocity perturbations to become oscillatory. We demonstrate that the oscillatory fluid motion reverses vortex roll-up and segregates the two streams leading to KHI suppression. Analysis and illustrations of the compressibility-induced suppression mechanism are presented.

  2. Myths and Truths of Nitinol Mechanics: Elasticity and Tension-Compression Asymmetry

    NASA Astrophysics Data System (ADS)

    Bucsek, Ashley N.; Paranjape, Harshad M.; Stebner, Aaron P.

    2016-08-01

    Two prevalent myths of Nitinol mechanics are examined: (1) Martensite is more compliant than austenite; (2) Texture-free Nitinol polycrystals do not exhibit tension-compression asymmetry. By reviewing existing literature, the following truths are revealed: (1) Martensite crystals may be more compliant, equally stiff, or stiffer than austenite crystals, depending on the orientation of the applied load. The Young's Modulus of polycrystalline Nitinol is not a fixed number—it changes with both processing and in operando deformations. Nitinol martensite prefers to behave stiffer under compressive loads and more compliant under tensile loads. (2) Inelastic Nitinol martensite deformation in and of itself is asymmetric, even for texture-free polycrystals. Texture-free Nitinol polycrystals also exhibit tension-compression transformation asymmetry.

  3. Research of mechanics of the compact bone microvolume and porous ceramics under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Kolmakova, T. V.; Buyakova, S. P.; Kul'kov, S. N.

    2015-11-01

    The research results of the mechanics are presented and the effective mechanical characteristics under uniaxial compression of the simulative microvolume of the compact bone are defined subject to the direction of the collagen-mineral fibers, porosity and mineral content. The experimental studies of the mechanics are performed and the effective mechanical characteristics of the produced porous zirconium oxide ceramics are defined. The recommendations are developed on the selection of the ceramic samples designed to replace the fragment of the compact bone of a definite structure and mineral content.

  4. Research of mechanics of the compact bone microvolume and porous ceramics under uniaxial compression

    SciTech Connect

    Kolmakova, T. V. Buyakova, S. P. Kul’kov, S. N.

    2015-11-17

    The research results of the mechanics are presented and the effective mechanical characteristics under uniaxial compression of the simulative microvolume of the compact bone are defined subject to the direction of the collagen-mineral fibers, porosity and mineral content. The experimental studies of the mechanics are performed and the effective mechanical characteristics of the produced porous zirconium oxide ceramics are defined. The recommendations are developed on the selection of the ceramic samples designed to replace the fragment of the compact bone of a definite structure and mineral content.

  5. Integrins mediate mechanical compression-induced endothelium-dependent vasodilation through endothelial nitric oxide pathway.

    PubMed

    Lu, Xiao; Kassab, Ghassan S

    2015-09-01

    Cardiac and skeletal muscle contraction lead to compression of intramuscular arterioles, which, in turn, leads to their vasodilation (a process that may enhance blood flow during muscle activity). Although endothelium-derived nitric oxide (NO) has been implicated in compression-induced vasodilation, the mechanism whereby arterial compression elicits NO production is unclear. We cannulated isolated swine (n = 39) myocardial (n = 69) and skeletal muscle (n = 60) arteriole segments and exposed them to cyclic transmural pressure generated by either intraluminal or extraluminal pressure pulses to simulate compression in contracting muscle. We found that the vasodilation elicited by internal or external pressure pulses was equivalent; moreover, vasodilation in response to pressure depended on changes in arteriole diameter. Agonist-induced endothelium-dependent and -independent vasodilation was used to verify endothelial and vascular smooth muscle cell viability. Vasodilation in response to cyclic changes in transmural pressure was smaller than that elicited by pharmacological activation of the NO signaling pathway. It was attenuated by inhibition of NO synthase and by mechanical removal of the endothelium. Stemming from previous observations that endothelial integrin is implicated in vasodilation in response to shear stress, we found that function-blocking integrin α5β1 or αvβ3 antibodies attenuated cyclic compression-induced vasodilation and NOx (NO(-)2 and NO(-)3) production, as did an RGD peptide that competitively inhibits ligand binding to some integrins. We therefore conclude that integrin plays a role in cyclic compression-induced endothelial NO production and thereby in the vasodilation of small arteries during cyclic transmural pressure loading.

  6. Coaxial carbon@boron nitride nanotube arrays with enhanced thermal stability and compressive mechanical properties

    NASA Astrophysics Data System (ADS)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Huang, Jingfeng; Tan, Dunlin; Zhang, Bowei; Teo, Edwin Hang Tong; Tok, Alfred Iing Yoong

    2016-05-01

    Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability. CNT arrays are grown using a commercially available thermal chemical vapor deposition (TCVD) technique and an outer BNNT with a wall thickness up to 1.37 nm is introduced by a post-growth TCVD treatment. Importantly, compared to the as-grown CNT arrays which deform almost plastically upon compression, the coaxial C@BNNT arrays exhibit an impressive ~4-fold increase in compressive strength with nearly full recovery after the first compression cycle at a 50% strain (76% recovery maintained after 10 cycles), as well as a significantly high and persistent energy dissipation ratio (~60% at a 50% strain after 100 cycles), attributed to the synergistic effect between the CNT and outer BNNT. Additionally, the as-prepared C@BNNT arrays show an improved structural stability in air at elevated temperatures, attributing to the outstanding thermal stability of the outer BNNT. This work provides new insights into tailoring the mechanical and thermal behaviours of arbitrary CNT arrays which enables a broader range of applications.Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability

  7. Gas-mediated vitreous compression: an experimental alternative to mechanized vitrectomy.

    PubMed

    Thresher, R J; Ehrenberg, M; Machemer, R

    1984-01-01

    We have developed a simple technique in rabbit and baboon eyes that utilizes intravitreally injected perfluoropropane gas, which expands slowly to efficiently compress and displace nearly completely the vitreous body. There is cataract formation after extended contact of the gas bubble with the lens. However, it is rapidly reversible by reducing the duration of lens contact (gas-fluid exchange) and by using young animals. No long-term alterations in intraocular pressure or retinal function were observed, as determined by electroretinography, during the 4-month test period. Gross examination and scanning electron microscopy revealed that the vitreous cavity, shortly after full expansion of the gas bubble, was practically free of collagen. The vitreous body had been detached from most of the retina and compressed into a collagenous strand between the optic nerve head and lens in the rabbit eyes, and there was also a dense collagen accumulation on the inferior retinal surface and anterior vitreous base in the rabbits and the baboon. Large areas of the retina and medullary wings were stripped of overlying collagen. By the end of 4 months, the compressed vitreous body had expanded to become an irregular structure that remained separated from the retina in areas of previous detachment. Mechanized vitrectomy is a difficult procedure often needed in experimental work. We believe that the vitreous compression and gas-fluid exchange technique is a valid alterative to a mechanical approach. We also believe that we have a model that simulates the human situation of posterior vitreous detachment and vitreous syneresis.

  8. On the Study of Lifting Mechanism of a Soft Porous Media under Fast Compression

    NASA Astrophysics Data System (ADS)

    Wu, Qianhong; Santhanam, S.; Nathan, R.; Vucbmss Team

    2015-11-01

    Fluid flow in a soft porous media under fast compressions is widely observed in biological systems and industrial applications. Despite of much progress, it remains unclear for the lifting mechanisms of the porous media due to the lack of complete experimental verifications of theoretical models. We report herein a unique approach to treat the limitation. The permeability of a synthetic fibrous porous media as a function of its compression was first measured. The material was then employed in a dynamic compression experiment using a porous-walled cylinder piston apparatus. The obtained transient compression of the porous media and the aforementioned permeability data were applied in different theoretical models for the pore pressure generation, which conclusively proved the validity of the consolidation theory developed by Wu et al. (JFM, 542, 281, 2005). Furthermore, the solid phase lifting force was separated from the total reaction force and was characterized by a new viscoelastic model, containing a nonlinear spring in conjunction with a linear viscoelastic Generalized Maxwell mechanical module. Excellent agreement was obtained between the experiment and the theory. Thus, the lifting forces from both the fluid and the solid were determined. This project is supported by NSF Grant 1511096.

  9. Mechanical Properties of AN ER Fluid in Tensile, Compression and Oscillatory Squeeze Tests

    NASA Astrophysics Data System (ADS)

    Vieira, S. L.; Nakano, M.; Oke, R.; Nagata, T.

    In this work, the mechanical properties of an anhydrous electrorheological fluid made of carbonaceous particles dispersed in silicone oil were determined in tensile, compression and oscillatory squeeze tests. The mechanical tests were carried out on a Mechanical Testling Machine and the device developed for measuring the ER properties was composed of two parallel steel electrodes between which the ER fluid was placed. The mechanical properties were measured for different DC electric field strengths, velocity and initial gap between the electrodes, and the ERF was tested in two different ways: (a) the fluid was placed between the electrodes (configuration 1) and (b) the electrodes were immersed inside the ERF (configuration 2). The results showed that the ER fluid is more resistant to compression than to tensile, and that the shape of the tensile stress-strain curve and the tensile strength varies with the electric field strength and the initial gap between the electrodes. The compressive stress increased with the increase of the electric field strength and with the decrease of the gap size and upper electrode velocity. In oscillatory test, for both configurations 1 and 2, increasing the oscillation frequency f and the number of cycles N produced a decrease of the damping performance of the ER fluid. Besides this, the damping force of each cycle in oscillatory tests increased with N. The electric field also played an important role on the shape of the hysteresis loop (stress as a function of fluid strain) for both configurations.

  10. Kronecker compressive sensing-based mechanism with fully independent sampling dimensions for hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Zhao, Rongqiang; Wang, Qiang; Shen, Yi

    2015-11-01

    We propose a new approach for Kronecker compressive sensing of hyperspectral (HS) images, including the imaging mechanism and the corresponding reconstruction method. The proposed mechanism is able to compress the data of all dimensions when sampling, which can be achieved by three fully independent sampling devices. As a result, the mechanism greatly reduces the control points and memory requirement. In addition, we can also select the suitable sparsifying bases and generate the corresponding optimized sensing matrices or change the distribution of sampling ratio for each dimension independently according to different HS images. As the cooperation of the mechanism, we combine the sparsity model and low multilinear-rank model to develop a reconstruction method. Analysis shows that our reconstruction method has a lower computational complexity than the traditional methods based on sparsity model. Simulations verify that the HS images can be reconstructed successfully with very few measurements. In summary, the proposed approach can reduce the complexity and improve the practicability for HS image compressive sensing.

  11. Cell mechanics using atomic force microscopy-based single-cell compression.

    PubMed

    Lulevich, Valentin; Zink, Tiffany; Chen, Huan-Yuan; Liu, Fu-Tong; Liu, Gang-Yu

    2006-09-12

    We report herein the establishment of a single-cell compression method based on force measurements in atomic force microscopy (AFM). The high-resolution bright-field or confocal laser scanning microscopy guides the location of the AFM probe and then monitors the deformation of cell shape, while microsphere-modified AFM probes compress the cell and measure the force. Force and deformation profiles of living cells reveal a cubic relationship at small deformation (<30%), multiple peaks at 30-70% compression, and a rapid increase at over 80% deformation. The initial compression may be described qualitatively and quantitatively using a simple model of a nonpermeable balloon filled with incompressible fluid. Stress peaks reflect cell membrane rupture, followed by the deformation and rupture of intracellular components, beyond which the cell responses become irreversible. The Young's modulus and bending constant of living cell membranes are extracted from the balloon models, with 10-30 MPa and 17-52 kT, respectively. The initial compression of dead and fixed cells is modeled using Hertzian contact theory, assuming that the cell is a homogeneous sphere. Dead cells exhibit a cytoskeleton elasticity of 4-7.5 kPa, while fixation treatment leads to a dramatic increase in the cytoskeletal Young's modulus (150-230 kPa) due to protein cross-linking by imine bonds. These results demonstrate the high sensitivity of the single-cell compression method to the molecular-level structural changes of cells, which suggests a new generic platform for investigating cell mechanics in tissue engineering and cancer research.

  12. Failure mechanisms in laminated carbon/carbon composites under biaxial compression

    SciTech Connect

    Grape, J.A.; Gupta, V.

    1995-07-01

    The failure mechanisms of 2D carbon/carbon (C/C) woven laminates have been determined under inplane biaxial compression loads, and the associated failure envelopes that account for the effect of matrix-type and loading directions were also obtained. The failure was in the form of micro-kinking of fiber bundles, interspersed with localized interply delaminations to form an overall shear fault. The shear fault was aligned with the major axis of loading except at above 75% of balanced biaxial compressive stress where failure occurred along both axes. Although the biaxial strength varied significantly with the ratio of in-plane principal stresses, R, there was no variation in the local failure mechanisms. Accordingly, it was found that the samples fail upon achieving a critical strain along the primary axis of loading.

  13. Transplant renal artery stenosis secondary to mechanical compression from polycystic kidney disease: A case report

    PubMed Central

    Lee, Linda; Gunaratnam, Lakshman; Sener, Alp

    2013-01-01

    Transplant renal artery stenosis (TRAS) is a potentially treatable cause of allograft dysfunction, hypertension and graft loss. The mainstay of treatment includes angioplasty and endovascular stenting, although observation and surgery are at times indicated. We present an unusual case of TRAS secondary to mechanical compression from a patient’s enlarged native polycystic kidneys. This was treated with bilateral native nephrectomy and evidence of TRAS improved both clinically and radiographically. Recognition and treatment are important in preventing irreversible complications of TRAS. PMID:23671537

  14. Chest x-ray

    MedlinePlus

    Chest radiography; Serial chest x-ray; X-ray - chest ... You stand in front of the x-ray machine. You will be told to hold your breath when the x-ray is taken. Two images are usually taken. You will ...

  15. Giant pericardial cyst mimicking dextrocardia on chest X-ray.

    PubMed

    Hamad, Hamad M; Galrinho, Ana; Abreu, João; Valente, Bruno; Bakero, Luis; Ferreira, Rui C

    2013-01-01

    Pericardial cysts are rare benign congenital malformations, usually small, asymptomatic and detected incidentally on chest X-ray as a mass located in the right costophrenic angle. Giant pericardial cysts are very uncommon and produce symptoms by compressing adjacent structures. In this report, the authors present a case of a symptomatic giant pericardial cyst incorrectly diagnosed as dextrocardia on chest X-ray.

  16. American College of Chest Physicians

    MedlinePlus

    ... of Certification (MOC) CHEST GAIN NSCLC CHEST SEEK Innovation, Simulation, and Training Center Professional Representative Education Program ( ... of Certification (MOC) CHEST GAIN NSCLC CHEST SEEK Innovation, Simulation, and Training Center Professional Representative Education Program ( ...

  17. Diaphragm pacing failure secondary to deteriorated chest wall mechanics: When a good diaphragm does not suffice to take a good breath in.

    PubMed

    Layachi, Lila; Georges, Marjolaine; Gonzalez-Bermejo, Jésus; Brun, Anne-Laure; Similowski, Thomas; Morélot-Panzini, Capucine

    2015-01-01

    Diaphragm pacing allows certain quadriplegic patients to be weaned from mechanical ventilation. Pacing failure can result from device dysfunction, neurotransmission failure, or degraded lung mechanics (such as atelectasis). We report two cases where progressive pacing failure was attributed to deteriorated chest wall mechanics. The first patient suffered from cervical spinal cord injury at age 45, was implanted with a phrenic stimulator (intrathoracic), successfully weaned from ventilation, and permanently paced for 7 years. Pacing effectiveness then slowly declined, finally attributed to rib cage stiffening due to ankylosing spondylitis. The second patient became quadriplegic after meningitis at age 15, was implanted with a phrenic stimulator (intradiaphragmatic) and weaned. After a year hypoventilation developed without obvious cause. In relationship with complex endocrine disorders, the patient had gained 31 kg. Pacing failure was attributed to excessive mechanical inspiratory load. Rib cage mechanics abnormalities should be listed among causes of diaphragm pacing failure and it should be kept in mind that a "good diaphragm" is not sufficient to produce a "good inspiration". PMID:26236593

  18. Effects of cement augmentation on the mechanical stability of multilevel spine after vertebral compression fracture

    PubMed Central

    Wang, Tian; Pelletier, Matthew H.; Walsh, William R.

    2016-01-01

    Background Studies on the effects of cement augmentation or vertebroplasty on multi-level spine after vertebral compression fractures are lacking. This paper seeks to establish a 3-vertebrae ovine model to determine the impact of compression fracture on spine biomechanics, and to discover if cement augmentation can restore mechanical stability to fractured spine. Methods Five lumbar spine segments (L1-L3) were obtained from 5-year-old female Merino sheep. Standardized wedge-compression fractures were generated in each L2 vertebra, and then augmented with polymethyl methacrylate (PMMA) cement mixed with 30% barium sulphate powder. Biomechanical pure moment testing in axial rotation (AR), flexion/extension (FE) and lateral bending (LB) was carried out in the intact, fractured and repaired states. Range of motion (ROM) and neutral zone (NZ) parameters were compared, and plain radiographs taken at every stage. Results Except for a significant increase in ROM between the intact and fractured states in AR between L1 and L2 (P<0.05), there were no other significant differences in ROM or NZ between the other groups. There was a trend towards an increase in ROM and NZ in all directions after fracture, but this did not reach significance. Normal biomechanics was only minimally restored after augmentation. Conclusions Results suggest that cement augmentation could not restore mechanical stability of fractured spine. Model-specific factors may have had a role in these findings. Caution should be exercised when applying these results to humans. PMID:27683707

  19. Effects of cement augmentation on the mechanical stability of multilevel spine after vertebral compression fracture

    PubMed Central

    Wang, Tian; Pelletier, Matthew H.; Walsh, William R.

    2016-01-01

    Background Studies on the effects of cement augmentation or vertebroplasty on multi-level spine after vertebral compression fractures are lacking. This paper seeks to establish a 3-vertebrae ovine model to determine the impact of compression fracture on spine biomechanics, and to discover if cement augmentation can restore mechanical stability to fractured spine. Methods Five lumbar spine segments (L1-L3) were obtained from 5-year-old female Merino sheep. Standardized wedge-compression fractures were generated in each L2 vertebra, and then augmented with polymethyl methacrylate (PMMA) cement mixed with 30% barium sulphate powder. Biomechanical pure moment testing in axial rotation (AR), flexion/extension (FE) and lateral bending (LB) was carried out in the intact, fractured and repaired states. Range of motion (ROM) and neutral zone (NZ) parameters were compared, and plain radiographs taken at every stage. Results Except for a significant increase in ROM between the intact and fractured states in AR between L1 and L2 (P<0.05), there were no other significant differences in ROM or NZ between the other groups. There was a trend towards an increase in ROM and NZ in all directions after fracture, but this did not reach significance. Normal biomechanics was only minimally restored after augmentation. Conclusions Results suggest that cement augmentation could not restore mechanical stability of fractured spine. Model-specific factors may have had a role in these findings. Caution should be exercised when applying these results to humans.

  20. A mechanism responsible for reducing compression strength of through-the-thickness reinforced composite material

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1992-01-01

    A study was conducted to identify one of the mechanisms that contributes to the reduced compression strength of composite materials with through-the-thickness (TTT) reinforcements. In this study a series of thick (0/90) laminates with stitched and integrally woven TTT reinforcements were fabricated and statically tested. In both the stitching and weaving process a surface loop of TTT reinforcement yarn is created between successive TTT penetrations. It was shown that the surface loop of the TTT reinforcement 'kinked' the in-plane fibers in such a manner that they were made ineffective in carrying compressive load. The improvement in strength by removal of the surface loop and 'kinked' in-plane fibers was between 7 and 35 percent.

  1. New compression mechanism in penile-scrotal lymphedema and sexual rehabilitation.

    PubMed

    de Godoy, Jose Maria Pereira; Facio, Fernando Nestor; de Carvalho, Eleni Cássia Matias; Godoy, Maria de Fatima Guerreiro

    2014-01-01

    The objective of this study is to describe a new compression mechanism in the treatment of lymphedema of the penis and scrotum and the ensuing sexual rehabilitation. The patient, a 58-year-old man, had edema of the penile and scrotal region as a result of surgery of the pancreas and spleen and chemotherapy. The patient complained of pain, discomfort, and difficulties to walk and urinate. A clinical diagnosis of lymphedema of the penis and scrotum was reached. Treatment involved the continuous use of a cotton-polyester compression garment for the region together with thorough hygiene skin care. The swelling reduced significantly within a week to almost a normal aspect which was accompanied by clinical improvements of the symptoms. The reduction in penile edema allowed sexual rehabilitation even though erectile dysfunction required the use of a specific medication (sildenafil). In conclusion, simple and low-cost options can improve lymphedema of the penis and scrotum and allow sexual rehabilitation. PMID:24669133

  2. Compressibility effects on the dynamic characteristics of gas lubricated mechanical components

    NASA Astrophysics Data System (ADS)

    Arghir, Mihai; Matta, Pierre

    2009-11-01

    The present Note deals with the effects of compressibility on the linearized dynamic characteristics of gas lubricated mechanical components (journal and thrust bearings). Although the effect of compressibility on the static characteristics is well known, its influence on the dynamic characteristics is still not clearly understood. The present Note uses Lubrication's simplest model problems (the 1D slider) to qualitatively describe this effect. An analytic solution obtained for the parallel 1D slider depicts the variation of stiffness and damping with the excitation frequency and shows that this nonlinearity must be taken into account for squeeze number larger than 1. A convenient way of handling this nonlinearity in a dynamic system is described for an aerodynamic thrust bearing. To cite this article: M. Arghir, P. Matta, C. R. Mecanique 337 (2009).

  3. Augmentation Improves Human Cadaveric Vertebral Body Compression Mechanics For Lumbar Total Disc Replacement

    PubMed Central

    Yoder, Jonathon H.; Auerbach, Joshua D.; Maurer, Philip M.; Erbe, Erik M.; Entrekin, Dean; Balderston, Richard A.; Bertagnoli, Rudolf; Elliott, Dawn M.

    2012-01-01

    Study Design Cadaveric biomechanical study. Objectives Quantify the effects of vertebral body augmentation on biomechanics under axial compression by a total disc replacement (TDR) implant. Summary of Background Data TDR is a surgical alternative to lumbar spinal fusion to treat degenerative disc disease. Osteoporosis in the adjacent vertebrae to the interposed TDR may lead to implant subsidence or vertebral body fracture. Vertebral augmentation is used to treat osteoporotic compression fracture. The study sought to evaluate whether vertebral augmentation improves biomechanics under TDR axial loading. Methods Forty-five L1-L5 lumbar vertebral body segments with intact posterior elements were used. Peripheral quantitative computed tomography scans were performed to determine bone density, block randomizing specimens by bone density into augmentation and control groups. A semi-constrained keeled lumbar disc replacement device was implanted providing 50% endplate coverage. Vertebral augmentation of 17.6 ± 0.9% vertebral volume fill with Cortoss was performed on augmentation group. All segments underwent axial compression at a rate of 0.2 mm/s to 6mm. Results The load-displacement response for all specimens was non-linear. Subfailure mechanical properties with augmentation were significantly different from control; in all cases the augmented group was 2× higher than control. At failure, the maximum load and stiffness with augmentation was not significantly different from control. The maximum apparent stress and modulus with augmentation were 2× and 1.3× greater than control, respectively. The subfailure stress and apparent modulus with augmentation was moderately correlated with bone density while the control subfailure properties were not. The augmented maximum stress was not correlated with bone density, while the control was weakly correlated. The maximum apparent modulus was moderately correlated with bone density for both the augmented and control groups

  4. Determination of the mechanical properties of solid and cellular polymeric dosage forms by diametral compression.

    PubMed

    Blaesi, Aron H; Saka, Nannaji

    2016-07-25

    At present, the immediate-release solid dosage forms, such as the oral tablets and capsules, are granular solids. They release drug rapidly and have adequate mechanical properties, but their manufacture is fraught with difficulties inherent in processing particulate matter. Such difficulties, however, could be overcome by liquid-based processing. Therefore, we have recently introduced polymeric cellular (i.e., highly porous) dosage forms prepared from a melt process. Experiments have shown that upon immersion in a dissolution medium, the cellular dosage forms with polyethylene glycol (PEG) as excipient and with predominantly open-cell topology disintegrate by exfoliation, thus enabling rapid drug release. If the volume fraction of voids of the open-cell structures is too large, however, their mechanical strength is adversely affected. At present, the common method for determining the tensile strength of brittle, solid dosage forms (such as select granular forms) is the diametral compression test. In this study, the theory of diametral compression is first refined to demonstrate that the relevant mechanical properties of ductile and cellular solids (i.e., the elastic modulus and the yield strength) can also be extracted from this test. Diametral compression experiments are then conducted on PEG-based solid and cellular dosage forms. It is found that the elastic modulus and yield strength of the open-cell structures are about an order of magnitude smaller than those of the non-porous solids, but still are substantially greater than the stiffness and strength requirements for handling the dosage forms manually. This work thus demonstrates that melt-processed polymeric cellular dosage forms that release drug rapidly can be designed and manufactured to have adequate mechanical properties.

  5. Experimental Investigation on Mechanical Behavior and Permeability Evolution of a Porous Limestone Under Compression

    NASA Astrophysics Data System (ADS)

    Han, B.; Xie, S. Y.; Shao, J. F.

    2016-09-01

    This paper presents an experimental investigation on the mechanical behavior and permeability evolution of a typical porous limestone, the Anstrude limestone. Hydrostatic and triaxial compression tests are first performed under drained condition to study the basic mechanical behavior of the porous rock. Permeability measurement under both hydrostatic and triaxial compression is carried out for investigating effects of stress state on the permeability evolution along the axial direction of sample. The obtained results allow to identifying two basic plastic deformation mechanisms, the plastic shearing and pore collapse, and their effects on the permeability evolution. Under low confining pressures, the permeability diminution in the elastic phase is controlled by deviatoric stress. After the onset of plastic shearing, the deviatoric stress induces a plastic volumetric dilatation and a permeability increase. When the deviatoric stress reaches the peak strength or after the onset of shear bands, the permeability slightly decreases. Under high confining pressures, the deviatoric stress also induces a permeability diminution before the onset of plastic pore collapse. After the onset of pore collapse, the deviatoric stress leads to a plastic volumetric compaction and permeability decrease. When the deviatoric stress reaches the onset of plastic shearing, the two plastic mechanisms are in competition, the permeability continuously decreases but with a reduced rate. Finally, after the compaction-dilatation transition, the plastic shearing dominates the deformation process while the pore collapse still controls the permeability evolution.

  6. Prediction of mechanical properties of compacted binary mixtures containing high-dose poorly compressible drug.

    PubMed

    Patel, Sarsvatkumar; Bansal, Arvind Kumar

    2011-01-17

    The aim of the study was to develop, compare and validate predictive model for mechanical property of binary systems. The mechanical properties of binary mixtures of ibuprofen (IBN) a poorly compressible high dose drug, were studied in presence of different excipients. The tensile strength of tablets of individual components viz. IBN, microcrystalline cellulose (MCC), and dicalcium phosphate dihydrate (DCP) and binary mixtures of IBN with excipients was measured at various relative densities. Prediction of the mechanical property of binary mixtures, from that of single components, was attempted using Ryshkewitch-Duckworth (R-D) and Percolation theory, by assuming a linear mixing rule or a power law mixing rule. The models were compared, and the best model was proposed based on the distribution of residuals and the Akaike's information criterion. Good predictions were obtained with the power law combined with linear mixing rule, using R-D and Percolation models. The results indicated that the proposed model can well predict the mechanical properties of binary system containing predominantly poorly compressible drug candidate. The predictions of these models and conclusions can be systematically generalized to other pharmaceutical powders.

  7. Mechanical response of porcine skin under compression from low to high strain rates

    NASA Astrophysics Data System (ADS)

    Bo, Chiara; Butler, Ben; Williams, Alun; Brown, Katherine; Proud, William

    2013-06-01

    Uniaxial compression experiments were performed on fresh porcine skin samples at different strain rates to study the stress-strain response. Low strain rate experiments were performed with an Instron 5566, while high strain rates were achieved using a Split Hopkinson Pressure Bar system. Magnesium bars and semiconductor strain gauges were used respectively to maximize the signal transmission from porcine skin to the output bar and to allow the signal measurement. Skin samples were harvested from different area of the animal to investigate the heterogeneity of such material. The experimental results showed that the mechanical response of skin in compression is strongly dependent on the strain rate of loading and on the location from which the samples were collected. Specimens collected from the rump showed a stiffer response compared to samples harvested from the thigh. Finally, a histological analysis of the samples post compression was carried out to examine the extent of tissue damage as a function of strain rate. This work is supported by the Atomic Weapons Establishment, UK and The Royal British Legion Centre for Blast Injury Studies at Imperial College London, UK.

  8. Failure mechanism analysis under compression loading of unidirectional carbon/epoxy composites using micromechanical modelling

    NASA Astrophysics Data System (ADS)

    Effendi, R. R.; Barrau, J.-J.; Guedra-Degeorges, D.

    An experimental study of the compression fracture of unidirectional composites (T300/914, T800/5245C, M40J/913, GY70/V108 and AS4/PEEK) shows that fiber kinking is the main failure mode. All materials tested exhibited a non-linear elastic behavior characterized by a continuous decrease of the tangent modulus as soon as the load was applied. A micromechanical model taking into account initial geometric imperfections was developed. Stress evolution in the constituents was analysed and then compared with their strength. Two failure modes were distinguished: failure due to the fracture of fibers and failure due to the fracture of matrix. This model demonstrates that the non-linear behavior is not due to the initial geometric imperfections. To refine modelling, a numerical analysis using a finite element method with elastoplastic and large displacement hypothesis was developed. This model not only shows the principals governing failure parameters: initial geometric impertions, yield stress of matrix and fiber compressive strength, but also demonstrates two failure mechanisms: fracture of fibers in compression and fiber kinking. This model confirms that the non-linear behavior is not attributed to the initial geometric imperfections.

  9. Influence of Tension-Compression Asymmetry on the Mechanical Behavior of AZ31B Magnesium Alloy Sheets in Bending

    NASA Astrophysics Data System (ADS)

    Zhou, Ping; Beeh, Elmar; Friedrich, Horst E.

    2016-03-01

    Magnesium alloys are promising materials for lightweight design in the automotive industry due to their high strength-to-mass ratio. This study aims to study the influence of tension-compression asymmetry on the radius of curvature and energy absorption capacity of AZ31B-O magnesium alloy sheets in bending. The mechanical properties were characterized using tension, compression, and three-point bending tests. The material exhibits significant tension-compression asymmetry in terms of strength and strain hardening rate due to extension twinning in compression. The compressive yield strength is much lower than the tensile yield strength, while the strain hardening rate is much higher in compression. Furthermore, the tension-compression asymmetry in terms of r value (Lankford value) was also observed. The r value in tension is much higher than that in compression. The bending results indicate that the AZ31B-O sheet can outperform steel and aluminum sheets in terms of specific energy absorption in bending mainly due to its low density. In addition, the AZ31B-O sheet was deformed with a larger radius of curvature than the steel and aluminum sheets, which brings a benefit to energy absorption capacity. Finally, finite element simulation for three-point bending was performed using LS-DYNA and the results confirmed that the larger radius of curvature of a magnesium specimen is mainly attributed to the high strain hardening rate in compression.

  10. Mechanical behavior and microstructure of compressed Ti foams synthesized via freeze casting.

    PubMed

    Jenei, Péter; Choi, Hyelim; Tóth, Adrián; Choe, Heeman; Gubicza, Jenő

    2016-10-01

    Pure Ti and Ti-5%W foams were prepared via freeze casting. The porosity and grain size of both the materials were 32-33% and 15-17µm, respectively. The mechanical behavior of the foams was investigated by uniaxial compression up to a plastic strain of ~0.26. The Young׳s moduli of both foams were ~23GPa, which was in good agreement with the value expected from their porosity. The Young׳s moduli of the foams were similar to the elastic modulus of cortical bones, thereby eliminating the osteoporosis-causing stress-shielding effect. The addition of W increased the yield strength from ~196MPa to ~235MPa. The microstructure evolution in the grains during compression was studied using electron backscatter diffraction (EBSD) and X-ray line profile analysis (XLPA). After compression up to a plastic strain of ~0.26, the average dislocation densities increased to ~3.4×10(14)m(-2) and ~5.9×10(14)m(-2) in the Ti and Ti-W foams, respectively. The higher dislocation density in the Ti-W foam can be attributed to the pinning effect of the solute tungsten atoms on dislocations. The experimentally measured yield strength was in good agreement with the strength calculated from the dislocation density and porosity. This study demonstrated that the addition of W to Ti foam is beneficial for biomedical applications, because the compressive yield strength increased while its Young׳s modulus remained similar to that of cortical bones. PMID:27469602

  11. Theoretical insight into the sensitive mechanism of multilayer-shaped cocrystal explosives: compression and slide.

    PubMed

    Gao, Hong-fei; Zhang, Shu-hai; Ren, Fu-de; Gou, Rui-jun; Han, Gang; Wu, Jing-bo; Ding, Xiong; Zhao, Wen-hu

    2016-05-01

    Multilayer-shaped compression and slide models were employed to investigate the complex sensitive mechanisms of cocrystal explosives in response to external mechanical stimuli. Here, density functional theory (DFT) calculations implementing the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) with the Tkatchenko-Scheffler (TS) dispersion correction were applied to a series of cocrystal explosives: diacetone diperoxide (DADP)/1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB), DADP/1,3,5-tribromo-2,4,6-trinitrobenzene (TBTNB) and DADP/1,3,5-triiodo-2,4,6-trinitrobenzene (TITNB). The results show that the GGA-PBE-TS method is suitable for calculating these cocrystal systems. Compression and slide models illustrate well the sensitive mechanism of layer-shaped cocrystals of DADP/TCTNB and DADP/TITNB, in accordance with the results from electrostatic potentials and free space per molecule in cocrystal lattice analyses. DADP/TCTNB and DADP/TBTNB prefer sliding along a diagonal direction on the a-c face and generating strong intermolecular repulsions, compared to DADP/TITNB, which slides parallel to the b-c face. The impact sensitivity of DADP/TBTNB is predicted to be the same as that of DADP/TCTNB, and the impact sensitivity of DADP/TBTNB may be slightly more insensitive than that of DADP and much more sensitive than that of TBTNB. PMID:27094730

  12. Quantitative mechanical analysis of thin compressible polymer monolayers on oxide surfaces.

    PubMed

    Huang, Qian; Yoon, Ilsun; Villanueva, Josh; Kim, Kanguk; Sirbuly, Donald J

    2014-10-28

    A clear understanding of the mechanical behavior of nanometer thick films on nanostructures, as well as developing versatile approaches to characterize their mechanical properties, are of great importance and may serve as the foundation for understanding and controlling molecular interactions at the interface of nanostructures. Here we report on the synthesis of thin, compressible polyethylene glycol (PEG) monolayers with a wet thickness of <20 nm on tin dioxide (SnO2) nanofibers through silane-based chemistries. Nanomechanical properties of such thin PEG films were extensively investigated using atomic force microscopy (AFM). In addition, tip-sample interactions were carefully studied, with different AFM tip modifications (i.e., hydrophilic and hydrophobic) and in different ionic solutions. We find that the steric forces dominate the tip-sample interactions when the polymer film is immersed in solution with salt concentrations similar to biological media (e.g., 1x phosphate buffer solution), while van der Waals and electrostatic forces have minimal contributions. A Dimitriadis thin film polymer compression model shows that the linear elastic regime is reproducible in the initial 50% indentation of these films which have tunable Young's moduli ranging from 5 MPa for the low molecular weight films to 700 kPa for the high molecular weight PEG films. Results are compared with the same PEG films deposited on silicon substrates which helped quantify the structural properties and understand the relationship between the structural and the mechanical properties of PEG films on the SnO2 fibers. PMID:25157609

  13. Enhanced densification, strength and molecular mechanisms in shock compressed porous silicon

    NASA Astrophysics Data System (ADS)

    Lane, J. Matthew D.; Vogler, Tracy J.

    2015-06-01

    In most porous materials, void collapse during shock compression couples mechanical energy to thermal energy. Increased temperature drives up pressures and lowers densities in the final Hugoniot states as compared to full-density samples. Some materials, however, exhibit an anomalous enhanced densification in their Hugoniot states when porosity is introduced. We have recently shown that silicon is such a material, and demonstrated a molecular mechanism for the effect using molecular simulation. We will review results from large-scale non-equilibrium molecular dynamics (NEMD) and Hugoniotstat simulations of shock compressed porous silicon, highlighting the mechanism by which porosity produces local shear which nucleate partial phase transition and localized melting at shock pressures below typical thresholds in these materials. Further, we will characterize the stress states and strength of the material as a function of porosity from 5 to 50 percent and with various porosity microstructures. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  14. A reduced mechanism for biodiesel surrogates with low temperature chemistry for compression ignition engine applications

    NASA Astrophysics Data System (ADS)

    Luo, Zhaoyu; Plomer, Max; Lu, Tianfeng; Som, Sibendu; Longman, Douglas E.

    2012-04-01

    Biodiesel is a promising alternative fuel for compression ignition (CI) engines. It is a renewable energy source that can be used in these engines without significant alteration in design. The detailed chemical kinetics of biodiesel is however highly complex. In the present study, a skeletal mechanism with 123 species and 394 reactions for a tri-component biodiesel surrogate, which consists of methyl decanoate, methyl 9-decanoate and n-heptane was developed for simulations of 3-D turbulent spray combustion under engine-like conditions. The reduction was based on an improved directed relation graph (DRG) method that is particularly suitable for mechanisms with many isomers, followed by isomer lumping and DRG-aided sensitivity analysis (DRGASA). The reduction was performed for pressures from 1 to 100 atm and equivalence ratios from 0.5 to 2 for both extinction and ignition applications. The initial temperatures for ignition were from 700 to 1800 K. The wide parameter range ensures the applicability of the skeletal mechanism under engine-like conditions. As such the skeletal mechanism is applicable for ignition at both low and high temperatures. Compared with the detailed mechanism that consists of 3299 species and 10806 reactions, the skeletal mechanism features a significant reduction in size while still retaining good accuracy and comprehensiveness. The validations of ignition delay time, flame lift-off length and important species profiles were also performed in 3-D engine simulations and compared with the experimental data from Sandia National Laboratories under CI engine conditions.

  15. Noncardiac chest pain: epidemiology, natural course and pathogenesis.

    PubMed

    Fass, Ronnie; Achem, Sami R

    2011-04-01

    Noncardiac chest pain is defined as recurrent chest pain that is indistinguishable from ischemic heart pain after a reasonable workup has excluded a cardiac cause. Noncardiac chest pain is a prevalent disorder resulting in high healthcare utilization and significant work absenteeism. However, despite its chronic nature, noncardiac chest pain has no impact on patients' mortality. The main underlying mechanisms include gastroesophageal reflux, esophageal dysmotility and esophageal hypersensitivity. Gastroesophageal reflux disease is likely the most common cause of noncardiac chest pain. Esophageal dysmotility affects only the minority of noncardiac chest pain patients. Esophageal hypersensitivity may be present in non-GERD-related noncardiac chest pain patients regardless if esophageal dysmotility is present or absent. Psychological co-morbidities such as panic disorder, anxiety, and depression are also common in noncardiac chest pain patients and often modulate patients' perception of disease severity. PMID:21602987

  16. Normal and Fibrotic Rat Livers Demonstrate Shear Strain Softening and Compression Stiffening: A Model for Soft Tissue Mechanics.

    PubMed

    Perepelyuk, Maryna; Chin, LiKang; Cao, Xuan; van Oosten, Anne; Shenoy, Vivek B; Janmey, Paul A; Wells, Rebecca G

    2016-01-01

    Tissues including liver stiffen and acquire more extracellular matrix with fibrosis. The relationship between matrix content and stiffness, however, is non-linear, and stiffness is only one component of tissue mechanics. The mechanical response of tissues such as liver to physiological stresses is not well described, and models of tissue mechanics are limited. To better understand the mechanics of the normal and fibrotic rat liver, we carried out a series of studies using parallel plate rheometry, measuring the response to compressive, extensional, and shear strains. We found that the shear storage and loss moduli G' and G" and the apparent Young's moduli measured by uniaxial strain orthogonal to the shear direction increased markedly with both progressive fibrosis and increasing compression, that livers shear strain softened, and that significant increases in shear modulus with compressional stress occurred within a range consistent with increased sinusoidal pressures in liver disease. Proteoglycan content and integrin-matrix interactions were significant determinants of liver mechanics, particularly in compression. We propose a new non-linear constitutive model of the liver. A key feature of this model is that, while it assumes overall liver incompressibility, it takes into account water flow and solid phase compressibility. In sum, we report a detailed study of non-linear liver mechanics under physiological strains in the normal state, early fibrosis, and late fibrosis. We propose a constitutive model that captures compression stiffening, tension softening, and shear softening, and can be understood in terms of the cellular and matrix components of the liver.

  17. Normal and Fibrotic Rat Livers Demonstrate Shear Strain Softening and Compression Stiffening: A Model for Soft Tissue Mechanics

    PubMed Central

    Cao, Xuan; van Oosten, Anne; Shenoy, Vivek B.; Janmey, Paul A.; Wells, Rebecca G.

    2016-01-01

    Tissues including liver stiffen and acquire more extracellular matrix with fibrosis. The relationship between matrix content and stiffness, however, is non-linear, and stiffness is only one component of tissue mechanics. The mechanical response of tissues such as liver to physiological stresses is not well described, and models of tissue mechanics are limited. To better understand the mechanics of the normal and fibrotic rat liver, we carried out a series of studies using parallel plate rheometry, measuring the response to compressive, extensional, and shear strains. We found that the shear storage and loss moduli G’ and G” and the apparent Young's moduli measured by uniaxial strain orthogonal to the shear direction increased markedly with both progressive fibrosis and increasing compression, that livers shear strain softened, and that significant increases in shear modulus with compressional stress occurred within a range consistent with increased sinusoidal pressures in liver disease. Proteoglycan content and integrin-matrix interactions were significant determinants of liver mechanics, particularly in compression. We propose a new non-linear constitutive model of the liver. A key feature of this model is that, while it assumes overall liver incompressibility, it takes into account water flow and solid phase compressibility. In sum, we report a detailed study of non-linear liver mechanics under physiological strains in the normal state, early fibrosis, and late fibrosis. We propose a constitutive model that captures compression stiffening, tension softening, and shear softening, and can be understood in terms of the cellular and matrix components of the liver. PMID:26735954

  18. Mechanism for amorphization of boron carbide B{sub 4}C under uniaxial compression

    SciTech Connect

    Aryal, Sitaram; Rulis, Paul; Ching, W. Y.

    2011-11-01

    Boron carbide undergoes an amorphization transition under high-velocity impacts, causing it to suffer a catastrophic loss in strength. The failure mechanism is not clear and this limits the ways to improve its resistance to impact. To help uncover the failure mechanism, we used ab initio methods to carry out large-scale uniaxial compression simulations on two polytypes of stoichiometric boron carbide (B{sub 4}C), B{sub 11}C-CBC, and B{sub 12}-CCC, where B{sub 11}C or B{sub 12} is the 12-atom icosahedron and CBC or CCC is the three-atom chain. The simulations were performed on large supercells of 180 atoms. Our results indicate that the B{sub 11}C-CBC (B{sub 12}-CCC) polytype becomes amorphous at a uniaxial strain s = 0.23 (0.22) and with a maximum stress of 168 (151) GPa. In both cases, the amorphous state is the consequence of structural collapse associated with the bending of the three-atom chain. Careful analysis of the structures after amorphization shows that the B{sub 11}C and B{sub 12} icosahedra are highly distorted but still identifiable. Calculations of the elastic coefficients (C{sub ij}) at different uniaxial strains indicate that both polytypes may collapse under a much smaller shear strain (stress) than the uniaxial strain (stress). On the other hand, separate simulations of both models under hydrostatic compression up to a pressure of 180 GPa show no signs of amorphization, in agreement with experimental observation. The amorphized nature of both models is confirmed by detailed analysis of the evolution of the radial pair distribution function, total density of states, and distribution of effective charges on atoms. The electronic structure and bonding of the boron carbide structures before and after amorphization are calculated to further elucidate the mechanism of amorphization and to help form the proper rationalization of experimental observations.

  19. Detailed Chemical Kinetic Reaction Mechanisms for Autoignition of Isomers of Heptane Under Rapid Compression

    SciTech Connect

    Westbrook, C K; Pitz, W J; Boercker, J E; Curran, H J; Griffiths, J F; Mohamed, C; Ribaucour, M

    2001-12-17

    Detailed chemical kinetic reaction mechanisms are developed for combustion of all nine isomers of heptane (C{sub 7}H{sub 16}), and these mechanisms are tested by simulating autoignition of each isomer under rapid compression machine conditions. The reaction mechanisms focus on the manner in which the molecular structure of each isomer determines the rates and product distributions of possible classes of reactions. The reaction pathways emphasize the importance of alkylperoxy radical isomerizations and addition reactions of molecular oxygen to alkyl and hydroperoxyalkyl radicals. A new reaction group has been added to past models, in which hydroperoxyalkyl radicals that originated with abstraction of an H atom from a tertiary site in the parent heptane molecule are assigned new reaction sequences involving additional internal H atom abstractions not previously allowed. This process accelerates autoignition in fuels with tertiary C-H bonds in the parent fuel. In addition, the rates of hydroperoxyalkylperoxy radical isomerization reactions have all been reduced so that they are now equal to rates of analogous alkylperoxy radical isomerizations, significantly improving agreement between computed and experimental ignition delay times in the rapid compression machine. Computed ignition delay times agree well with experimental results in the few cases where experiments have been carried out for specific heptane isomers, and predictive model calculations are reported for the remaining isomers. The computed results fall into three general groups; the first consists of the most reactive isomers, including n-heptane, 2-methyl hexane and 3-methyl hexane. The second group consists of the least reactive isomers, including 2,2-dimethyl pentane, 3,3-dimethyl pentane, 2,3-dimethyl pentane, 2,4-dimethyl pentane and 2,2,3-trimethyl butane. The remaining isomer, 3-ethyl pentane, was observed computationally to have an intermediate level of reactivity. These observations are generally

  20. A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting.

    PubMed

    Li, Xiaotian; Guo, Mingsen; Dong, Shuxiang

    2011-04-01

    A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz.

  1. Electrical, mechanical and morphological properties of compressed carbon felt electrodes in vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Chang, Tien-Chan; Zhang, Jun-Pu; Fuh, Yiin-Kuen

    2014-01-01

    Experiments including electrical, mechanical and morphological aspects under compression in the range of 0-40% have been carried out on four potential materials for liquid diffusion layer (LDL) of vanadium redox flow battery (VRB) (including three widely used carbon felt and one recently utilized metal foam) in order to better understand the influence of the fundamental properties on the battery performance. We experimentally demonstrate that the electrical contact resistance is predominately determined by the clamping force. It is observed that increasing the stress applied on the carbon felt, which is of high interest for the durability of the membrane electrode assembly (MEA), has moreover a positive effect on their performance due to the reduced contact resistance. However, a simultaneously reduced porosity is also recorded and possibly detrimental to the mass transport of vanadium electrolyte. Moreover, the intrusion of carbon felts under compression is also characterized. Experimental results show that with the clamping force increases, both the porosity of the carbon felts underneath the rib and channel volume decrease, and this can be mainly attributed to the deformation of the carbon felts and resultant changed of the void volume as well as intrusion.

  2. A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting.

    PubMed

    Li, Xiaotian; Guo, Mingsen; Dong, Shuxiang

    2011-04-01

    A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz. PMID:21507747

  3. A new mechanical device for circular compression anastomosis. Preliminary results of animal and clinical experimentation.

    PubMed Central

    Rosati, R; Rebuffat, C; Pezzuoli, G

    1988-01-01

    The authors report the preliminary results obtained in animal and clinical experimentation of a new mechanical device for circular anastomosis which they have developed. It is a gun that places an apparatus consisting of three polypropylene rings that, through the compression among them of the severed edges of the bowel, realize a sutureless anastomosis and are spontaneously evacuated. Fifty-eight colonic anastomoses were performed in dogs with this device; 23 stapled colonic anastomoses were also executed concurrently. Forty-four animals underwent a relaparotomy to remove the colonic specimen containing the anastomoses. Bursting pressure and the histologic features of the anastomoses were evaluated at different time intervals after operation. A good healing of all compression anastomoses was observed, thereby allowing them to initiate the experience in humans. Thirteen anastomoses (6 colorectal extraperitoneal, 1 colorectal intraperitoneal, 5 colocolonic, 1 ileorectal) were performed at the 1st Surgical Department, Milan University. One subclinical leakage (7.7%) spontaneously healed in a few days. No stenoses were observed. Images Fig. 1. Fig. 2., Fig. 4., Fig. 6. Fig. 3., Fig. 5., Fig. 7. Fig. 8. Fig. 9. PMID:3345111

  4. Dural venous sinuses distortion and compression with supratentorial mass lesions: a mechanism for refractory intracranial hypertension?

    PubMed Central

    Qureshi, Adnan I.; Qureshi, Mushtaq H.; Majidi, Shahram; Gilani, Waqas I.; Siddiq, Farhan

    2014-01-01

    Objective To determine the effect of supratentorial intraparenchymal mass lesions of various volumes on dural venous sinuses structure and transluminal pressures. Methods Three set of preparations were made using adult isolated head derived from fresh human cadaver. A supratentorial intraparenchymal balloon was introduced and inflated at various volumes and effect on dural venous sinuses was assessed by serial intravascular ultrasound, computed tomographic (CT), and magnetic resonance (MR) venograms. Contrast was injected through a catheter placed in sigmoid sinus for both CT and MR venograms. Serial trasluminal pressures were measured from middle part of superior sagittal sinus in another set of experiments. Results At intraparenchymal balloon inflation of 90 cm3, there was attenuation of contrast enhancement of superior sagittal sinus with compression visualized in posterior part of the sinus without any evidence of compression in the remaining sinus. At intraparenchymal balloon inflation of 180 and 210 cm3, there was compression and obliteration of superior sagittal sinus throughout the length of the sinus. In the coronal sections, at intraparenchymal balloon inflations of 90 and 120 cm3, compression and obliteration of the posterior part of superior sagittal sinus were visualized. In the axial images, basal veins were not visualized with intraparenchymal balloon inflation of 90 cm3 or greater although straight sinus was visualized at all levels of inflation. Trasluminal pressure in the middle part of superior sagittal sinus demonstrated a mild increase from 0 cm H2O to 0.4 cm H2O and 0.5 cm H2O with inflation of balloon to volume of 150 and 180 cm3, respectively. There was a rapid increase in transluminal pressure from 6.8 cm H2O to 25.6 cm H2O as the supratentorial mass lesion increased from 180 to 200 cm3. Conclusions Our experiments identified distortion and segmental and global obliteration of dural venous sinuses secondary to supratentorial mass lesion and

  5. Mechanical characterization of brain tissue in compression at dynamic strain rates.

    PubMed

    Rashid, Badar; Destrade, Michel; Gilchrist, Michael D

    2012-06-01

    Traumatic brain injury (TBI) occurs when local mechanical load exceeds certain tolerance levels for brain tissue. Extensive research has been done previously for brain matter experiencing compression at quasistatic loading; however, limited data is available to model TBI under dynamic impact conditions. In this research, an experimental setup was developed to perform unconfined compression tests and stress relaxation tests at strain rates ≤90/s. The brain tissue showed a stiffer response with increasing strain rates, showing that hyperelastic models are not adequate. Specifically, the compressive nominal stress at 30% strain was 8.83 ± 1.94, 12.8 ± 3.10 and 16.0 ± 1.41 kPa (mean ± SD) at strain rates of 30, 60 and 90/s, respectively. Relaxation tests were also conducted at 10%-50% strain with the average rise time of 10 ms, which can be used to derive time dependent parameters. Numerical simulations were performed using one-term Ogden model with initial shear modulus μ(o)=6.06±1.44, 9.44 ± 2.427 and 12.64 ± 1.227 kPa (mean ± SD) at strain rates of 30, 60 and 90/s, respectively. A separate set of bonded and lubricated tests were also performed under the same test conditions to estimate the friction coefficient μ, by adopting combined experimental-computational approach. The values of μ were 0.1 ± 0.03 and 0.15 ± 0.07 (mean ± SD) at 30 and 90/s strain rates, respectively, indicating that pure slip conditions cannot be achieved in unconfined compression tests even under fully lubricated test conditions. The material parameters obtained in this study will help to develop biofidelic human brain finite element models, which can subsequently be used to predict brain injuries under impact conditions. PMID:22520416

  6. Failure analysis of porcupine quills under axial compression reveals their mechanical response during buckling.

    PubMed

    Torres, Fernando G; Troncoso, Omar P; Diaz, John; Arce, Diego

    2014-11-01

    Porcupine quills are natural structures formed by a thin walled conical shell and an inner foam core. Axial compression tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR) were all used to compare the characteristics and mechanical properties of porcupine quills with and without core. The failure mechanisms that occur during buckling were analyzed by scanning electron microscopy (SEM), and it was found that delamination buckling is mostly responsible for the decrease in the measured buckling stress of the quills with regard to predicted theoretical values. Our analysis also confirmed that the foam core works as an energy dissipater improving the mechanical response of an empty cylindrical shell, retarding the onset of buckling as well as producing a step wise decrease in force after buckling, instead of an instantaneous decrease in force typical for specimens without core. Cell collapse and cell densification in the inner foam core were identified as the key mechanisms that allow for energy absorption during buckling.

  7. Failure analysis of porcupine quills under axial compression reveals their mechanical response during buckling.

    PubMed

    Torres, Fernando G; Troncoso, Omar P; Diaz, John; Arce, Diego

    2014-11-01

    Porcupine quills are natural structures formed by a thin walled conical shell and an inner foam core. Axial compression tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR) were all used to compare the characteristics and mechanical properties of porcupine quills with and without core. The failure mechanisms that occur during buckling were analyzed by scanning electron microscopy (SEM), and it was found that delamination buckling is mostly responsible for the decrease in the measured buckling stress of the quills with regard to predicted theoretical values. Our analysis also confirmed that the foam core works as an energy dissipater improving the mechanical response of an empty cylindrical shell, retarding the onset of buckling as well as producing a step wise decrease in force after buckling, instead of an instantaneous decrease in force typical for specimens without core. Cell collapse and cell densification in the inner foam core were identified as the key mechanisms that allow for energy absorption during buckling. PMID:25123434

  8. Prevalence and mechanism of triazole resistance in Aspergillus fumigatus in a referral chest hospital in Delhi, India and an update of the situation in Asia

    PubMed Central

    Chowdhary, Anuradha; Sharma, Cheshta; Kathuria, Shallu; Hagen, Ferry; Meis, Jacques F.

    2015-01-01

    Aspergillus fumigatus causes varied clinical syndromes ranging from colonization to deep infections. The mainstay of therapy of Aspergillus diseases is triazoles but several studies globally highlighted variable prevalence of triazole resistance, which hampers the management of aspergillosis. We studied the prevalence of resistance in clinical A. fumigatus isolates during 4 years in a referral Chest Hospital in Delhi, India and reviewed the scenario in Asia and the Middle East. Aspergillus species (n = 2117) were screened with selective plates for azole resistance. The isolates included 45.4% A. flavus, followed by 32.4% A. fumigatus, 15.6% Aspergillus species and 6.6% A. terreus. Azole resistance was found in only 12 (1.7%) A. fumigatus isolates. These triazole resistant A. fumigatus (TRAF) isolates were subjected to (a) calmodulin and β tubulin gene sequencing (b) in vitro antifungal susceptibility testing against triazoles using CLSI M38-A2 (c) sequencing of cyp51A gene and real-time PCR assay for detection of mutations and (d) microsatellite typing of the resistant isolates. TRAF harbored TR34/L98H mutation in 10 (83.3%) isolates with a pan-azole resistant phenotype. Among the remaining two TRAF isolates, one had G54E and the other had three non-synonymous point mutations. The majority of patients were diagnosed as invasive aspergillosis followed by allergic bronchopulmonary aspergillosis and chronic pulmonary aspergillosis. The Indian TR34/L98H isolates had a unique genotype and were distinct from the Chinese, Middle East, and European TR34/L98H strains. This resistance mechanism has been linked to the use of fungicide azoles in agricultural practices in Europe as it has been mainly reported from azole naïve patients. Reports published from Asia demonstrate the same environmental resistance mechanism in A. fumigatus isolates from two highly populated countries in Asia, i.e., China and India and also from the neighboring Middle East. PMID:26005442

  9. Synchronization of radiograph film exposure with the inspiratory pause. Effect on the appearance of bedside chest radiographs in mechanically ventilated patients.

    PubMed

    Langevin, P B; Hellein, V; Harms, S M; Tharp, W K; Cheung-Seekit, C; Lampotang, S

    1999-12-01

    The appearance of portable chest radiographs (CXRs) may be affected by changes in ventilation, particularly when patients are mechanically ventilated. Synchronization of the CXR with the ventilatory cycle should limit the influence of respiratory variation on the appearance of the CXR. This study evaluates the effect of synchronizing the CXR film exposure with ventilation on the appearance of the radiograph. Twenty-five patients who remained intubated postoperatively, were mechanically ventilated, and required a CXR were enrolled in this triple-blind, randomized prospective study. Each patient received one radiograph using conventional techniques and another using the interface. The sequence of the two films was randomized, and the two films were taken on the same patient within a few minutes of each other. Hence, each patient served as his own control and the position of the patient, source-film distance, intensity (Kvp), and duration of the exposure (mAs) were identical for the two films. Five board-certified radiologists were then asked to compare paired films for clarity of lines and tubes, definition of the pulmonary vasculature, visibility of the mediastinum, definition of the diaphragm, and degree of lung inflation. Radiologists were also asked to choose which films they preferred. A majority of board certified radiologists preferred CXRs taken with the interface in 21 of 25 patients (p < 0.0001). Furthermore, four of the five criteria evaluated were improved (p < 0.05) on synchronized CXRs. Synchronization of the bedside CXR with the end of inspiration ensures that they are always obtained at maximal inflation, which improves the appearance of a majority of radiographs by at least one of five criteria. PMID:10588630

  10. Computer-aided study of the mechanical behavior of the jaw bone fragments under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Kolmakova, Tatyana V.

    2016-08-01

    The article presents the calculated results of the mechanical behavior of simulative bone mesovolumes under uniaxial compression with their architectonics corresponding to the human jaw bone fragments. The results of the calculation show that changes in the structure and mineral content of the bone fragments can lead to the change of their prevailing deformation response. New effective parameters were introduced to reflect the character of the distribution of stresses and strains in the bone mesovolumes. Implants are to be created and selected to correspond to the offered parameters and longitudinal modulus of elasticity of bone mesovolumes in order to maintain the stress and strain state existing in bone macrovolume during the implantation and in order to avoid bone restructuring through its borderline resorption.

  11. Transforming powder mechanical properties by core/shell structure: compressible sand.

    PubMed

    Shi, Limin; Sun, Changquan Calvin

    2010-11-01

    Some active pharmaceutical ingredients possess poor mechanical properties and are not suitable for tableting. Using fine sand (silicon dioxide), we show that a core/shell structure, where a core particle (sand) is coated with a thin layer of polyvinylpyrrolidone (PVP), can profoundly improve powder compaction properties. Sand coated with 5% PVP could be compressed into intact tablets. Under a given compaction pressure, tablet tensile strength increases dramatically with the amount of coating. This is in sharp contrast to poor compaction properties of physical mixtures, where intact tablets cannot be made when PVP content is 20% or less. The profoundly improved tabletability of core/shell particles is attributed to the formation of a continuous three-dimensional bonding network in the tablet.

  12. Compressed Sensing in a Fully Non-Mechanical 350 GHz Imaging Setting

    NASA Astrophysics Data System (ADS)

    Augustin, S.; Hieronymus, J.; Jung, P.; Hübers, H.-W.

    2015-05-01

    We investigate a single-pixel camera (SPC) that relies on non-mechanical scanning with a terahertz (THz) spatial light modulator (SLM) and Compressed Sensing (CS) for image generation. The camera is based on a 350 GHz multiplier source and a Golay cell detector. The SLM consists of a Germanium disc, which is illuminated by a halogen lamp. The light of the lamp is transmitted through a thin-film transistor (TFT) liquid crystal display (LCD). This enables the generation of light patterns on the Germanium disc, which in turn produce reflecting patterns for THz radiation. Using up to 1000 different patterns the pseudo-inverse reconstruction algorithm and the CS algorithm CoSaMP are evaluated with respect to image quality. It is shown that CS allows a reduction of the necessary measurements by a factor of three without compromising the image quality.

  13. Mechanism of hollow-core-fiber infrared-supercontinuum compression with bulk material

    SciTech Connect

    Bejot, P.; Schmidt, B. E.; Legare, F.; Kasparian, J.; Wolf, J.-P.

    2010-06-15

    We numerically investigate the pulse compression mechanism in the infrared spectral range based on the successive action of nonlinear pulse propagation in a hollow-core fiber followed by linear propagation through bulk material. We found an excellent agreement of simulated pulse properties with experimental results at 1.8 {mu}m in the two-optical-cycle regime close to the Fourier limit. In particular, the spectral phase asymmetry attributable to self-steepening combined with self-phase modulation is a necessary prerequisite for subsequent compensation by the phase introduced by glass material in the anomalous dispersion regime. The excellent agreement of the model enabled simulating pressure and wavelength tunability of sub-two cycles in the range from 1.5 to 4 {mu}m with this cost-efficient and robust approach.

  14. An analysis of the mechanical parameters used for finite element compression of a high-resolution 3D breast phantom

    PubMed Central

    Hsu, Christina M. L.; Palmeri, Mark L.; Segars, W. Paul; Veress, Alexander I.; Dobbins, James T.

    2011-01-01

    Purpose: The authors previously introduced a methodology to generate a realistic three-dimensional (3D), high-resolution, computer-simulated breast phantom based on empirical data. One of the key components of such a phantom is that it provides a means to produce a realistic simulation of clinical breast compression. In the current study, they have evaluated a finite element (FE) model of compression and have demonstrated the effect of a variety of mechanical properties on the model using a dense mesh generated from empirical breast data. While several groups have demonstrated an effective compression simulation with lower density finite element meshes, the presented study offers a mesh density that is able to model the morphology of the inner breast structures more realistically than lower density meshes. This approach may prove beneficial for multimodality breast imaging research, since it provides a high level of anatomical detail throughout the simulation study. Methods: In this paper, the authors describe methods to improve the high-resolution performance of a FE compression model. In order to create the compressible breast phantom, dedicated breast CT data was segmented and a mesh was generated with 4-noded tetrahedral elements. Using an explicit FE solver to simulate breast compression, several properties were analyzed to evaluate their effect on the compression model including: mesh density, element type, density, and stiffness of various tissue types, friction between the skin and the compression plates, and breast density. Following compression, a simulated projection was generated to demonstrate the ability of the compressible breast phantom to produce realistic simulated mammographic images. Results: Small alterations in the properties of the breast model can change the final distribution of the tissue under compression by more than 1 cm; which ultimately results in different representations of the breast model in the simulated images. The model

  15. Ventilation in chest trauma

    PubMed Central

    Richter, Torsten; Ragaller, Maximilian

    2011-01-01

    Chest trauma is one important factor for total morbidity and mortality in traumatized emergency patients. The complexity of injury in trauma patients makes it challenging to provide an optimal oxygenation while protecting the lung from further ventilator-induced injury to it. On the other hand, lung trauma needs to be treated on an individual basis, depending on the magnitude, location and type of lung or chest injury. Several aspects of ventilatory management in emergency patients are summarized herein and may give the clinician an overview of the treatment possibilities for chest trauma victims. PMID:21769213

  16. Deformation mechanism of basic rock during long-term compression: Area of HLW repository design, Chelyabinsk District, Russia

    SciTech Connect

    Petrov, V.A.; Zviagintsev, L.I.; Poluektov, V.V.

    1996-08-01

    A combination of ultrasound, mechanical and petrographic results for long-term experimental compression of greenschist facies porphyritic andesite tuffs indicate a deformation mechanism that depends upon the mineral composition, textural-structural features of the rocks and the orientation of compression relative to the rock textures. Three dry samples of rock were investigated. Coaxial compression of a massive sample for 816 hours and a foliated sample for 1,176 hours (pressure orthogonal to foliation) is characterized by solidification when the rocks are temporarily metastable. Compressive strength of the first sample is 850 kg/cm{sup 2} and of the second one, 800 kg/cm{sup 2}. Experimentally, the rock behavior changes from a plastic to a brittle regime of deformation. In contrast, compression of the foliated sample parallel to foliation causes disintegration along the foliation within 480 hours without solidification. The rock is liable to brittle deformation and its compressive strength is 500 kg/cm{sup 2}. These results may have implications for characterization of near-field processes in connection with numerous subhorizontal zones of schistosity within the strata that are targeted for underground disposal of high-level wastes (HLW) in the Mayak radiochemical complex area.

  17. Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

    SciTech Connect

    Yuan, Fuping Wu, Xiaolei

    2014-12-15

    A series of large-scale molecular dynamics simulations were conducted to investigate the scaling laws and the related atomistic deformation mechanisms of Cu monocrystal samples containing randomly placed nanovoids under adiabatic uniaxial strain compression. At onset of yielding, plastic deformation is accommodated by dislocations emitted from void surfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from void surfaces and their interactions with further plastic deformation. The simulation results also suggest that the effect modulus, the yield stress and the energy aborption density of samples under uniaxial strain are linearly proportional to the relative density ρ. Moreover, the yield stress, the average flow stress and the energy aborption density of samples with the same relative density show a strong dependence on the void diameter d, expressed by exponential relations with decay coefficients much higher than -1/2. The corresponding atomistic mechanisms for scaling laws of the relative density and the void diameter were also presented. The present results should provide insights for understanding deformation mechanisms of nanoporous metals under extreme conditions.

  18. Chest Injuries and Disorders

    MedlinePlus

    ... your neck and your abdomen. It includes the ribs and breastbone. Inside your chest are several organs, ... and collapsed lung Pleural disorders Esophagus disorders Broken ribs Thoracic aortic aneurysms Disorders of the mediastinum, the ...

  19. Dynamic Compression Effects on Immature Nucleus Pulposus: a Study Using a Novel Intelligent and Mechanically Active Bioreactor

    PubMed Central

    Li, Pei; Gan, Yibo; Wang, Haoming; Zhang, Chengmin; Wang, Liyuan; Xu, Yuan; Song, Lei; Li, Songtao; Li, Sukai; Ou, Yangbin; Zhou, Qiang

    2016-01-01

    Background: Previous cell culture and animal in vivo studies indicate the obvious effects of mechanical compression on disc cell biology. However, the effects of dynamic compression magnitude, frequency and duration on the immature nucleus pulposus (NP) from an organ-cultured disc are not well understood. Objective: To investigate the effects of a relatively wide range of compressive magnitudes, frequencies and durations on cell apoptosis and matrix composition within the immature NP using an intelligent and mechanically active bioreactor. Methods: Discs from the immature porcine were cultured in a mechanically active bioreactor for 7 days. The discs in various compressive magnitude groups (0.1, 0.2, 0.4, 0.8 and 1.3 MPa at a frequency of 1.0 Hz for 2 hours), frequency groups (0.1, 0.5, 1.0, 3.0 and 5.0 Hz at a magnitude of 0.4 MPa for 2 hours) and duration groups (1, 2, 4 and 8 hours at a magnitude of 0.4 MPa and frequency of 1.0 Hz) experienced dynamic compression once per day. Discs cultured without compression were used as controls. Immature NP samples were analyzed using the TUNEL assay, histological staining, glycosaminoglycan (GAG) content measurement, real-time PCR and collagen II immunohistochemical staining. Results: In the 1.3 MPa, 5.0 Hz and 8 hour groups, the immature NP showed a significantly increase in apoptotic cells, a catabolic gene expression profile with down-regulated matrix molecules and up-regulated matrix degradation enzymes, and decreased GAG content and collagen II deposition. In the other compressive magnitude, frequency and duration groups, the immature NP showed a healthier status regarding NP cell apoptosis, gene expression profile and matrix production. Conclusion: Cell apoptosis and matrix composition within the immature NP were compressive magnitude-, frequency- and duration-dependent. The relatively high compressive magnitude or frequency and long compressive duration are not helpful for maintaining the healthy status of an

  20. Mechanical compression insults induce nanoscale changes of membrane-skeleton arrangement which could cause apoptosis and necrosis in dorsal root ganglion neurons.

    PubMed

    Quan, Xin; Guo, Kai; Wang, Yuqing; Huang, Liangliang; Chen, Beiyu; Ye, Zhengxu; Luo, Zhuojing

    2014-01-01

    In a primary spinal cord injury, the amount of mechanical compression insult that the neurons experience is one of the most critical factors in determining the extent of the injury. The ultrastructural changes that neurons undergo when subjected to mechanical compression are largely unknown. In the present study, using a compression-driven instrument that can simulate mechanical compression insult, we applied mechanical compression stimulation at 0.3, 0.5, and 0.7 MPa to dorsal root ganglion (DRG) neurons for 10 min. Combined with atomic force microscopy, we investigated nanoscale changes in the membrane-skeleton, cytoskeleton alterations, and apoptosis induced by mechanical compression injury. The results indicated that mechanical compression injury leads to rearrangement of the membrane-skeleton compared with the control group. In addition, mechanical compression stimulation induced apoptosis and necrosis and also changed the distribution of the cytoskeleton in DRG neurons. Thus, the membrane-skeleton may play an important role in the response to mechanical insults in DRG neurons. Moreover, sudden insults caused by high mechanical compression, which is most likely conducted by the membrane-skeleton, may induce necrosis, apoptosis, and cytoskeletal alterations.

  1. Gallium Arsenate Dihydrate under Pressure: Elastic Properties, Compression Mechanism, and Hydrogen Bonding.

    PubMed

    Spencer, Elinor C; Soghomonian, Victoria; Ross, Nancy L

    2015-08-01

    Gallium arsenate dihydrate is a member of a class of isostructural compounds, with the general formula M(3+)AsO4·2H2O (M(3+) = Fe, Al, In, or Ga), which are being considered as potential solid-state storage media for the sequestration of toxic arsenic cations. We report the first high-pressure structural analysis of a metal arsenate dihydrate, namely, GaAsO4·2H2O. This compound crystallizes in the orthorhombic space group Pbca with Z = 8. Accurate unit cell parameters as a function of pressure were obtained by high-pressure single-crystal X-ray diffraction, and a bulk modulus of 51.1(3) GPa for GaAsO4·2H2O was determined from a third-order Birch-Murnaghan equation of state fit to the P-V data. Assessment of the pressure dependencies of the unit cell lengths showed that the compressibility of the structure along the axial directions increases in the order of [010] < [100] < [001]. This order was found to correlate well with the proposed compression mechanism for GaAsO4·2H2O, which involves deformation of the internal channel void spaces of the polyhedral helices that lie parallel to the [010] direction, and increased distortion of the GaO6 octahedra. The findings of the high-pressure diffraction experiment were further supported by the results from variable-pressure Raman analysis of GaAsO4·2H2O. Moreover, we propose a revised and more complex model for the hydrogen-bonding scheme in GaAsO4·2H2O, and on the basis of this revision, we reassigned the peaks in the OH stretching regions of previously published Raman spectra of this compound.

  2. Statistical mechanics description of an isotropic compression and its relationship to micromechanics

    NASA Astrophysics Data System (ADS)

    Oquendo, W. F.; Muñoz, J. D.

    2013-06-01

    Statistical mechanics of volumes have been used to describe static packings of grains, usually grown by deposition or after shaking. In the present work, we use molecular dynamic simulations and the Gamma distribution of volumes introduced by Aste et. al [1, 2] to explore the limit equilibrium state of isotropic compression on a monodisperse system of spheres with sliding and rolling friction. The objective is to investigate how the volume entropy S, the compactivity χ and the number of elementary cells per particle C/N change with the microscopic force parameters among grains. First, we found that the volume distribution of the Voronoi tessellation on the final state actually follows the Gamma distribution proposed by Aste et. al. Next, we found that both S and χ grow smoothly by a factor of two with an increasing sliding friction coefficient μs, which, therefore, could be used as tunning parameter for these statistical variables. They also grow with the rolling friction coefficient μr, but for a smaller factor and reaching saturation very early. In contrast, C/N is almost unaffected by μr (between the error bars) and saturates for very small values of μs, but it can be reduced in around a 10% by decreasing the reduced elastic constant κ in two orders of magnitude, a change that does leave χ almost unaffected. These results drive the attention on μs as the most meaningful variable to control the reorganizations of grains through the isotropic compression and, thus, the statistical properties of its final state.

  3. Energy efficient of ethanol recovery in pervaporation membrane bioreactor with mechanical vapor compression eliminating the cold traps.

    PubMed

    Fan, Senqing; Xiao, Zeyi; Li, Minghai

    2016-07-01

    An energy efficient pervaporation membrane bioreactor with mechanical vapor compression was developed for ethanol recovery during the process of fermentation coupled with pervaporation. Part of the permeate vapor at the membrane downstream under the vacuum condition was condensed by running water at the first condenser and the non-condensed vapor enriched with ethanol was compressed to the atmospheric pressure and pumped into the second condenser, where the vapor was easily condensed into a liquid by air. Three runs of fermentation-pervaporation experiment have been carried out lasting for 192h, 264h and 360h respectively. Complete vapor recovery validated the novel pervaporation membrane bioreactor. The total flux of the polydimethylsiloxane (PDMS) membrane was in the range of 350gm(-2)h(-1) and 600gm(-2)h(-1). Compared with the traditional cold traps condensation, mechanical vapor compression behaved a dominant energy saving feature. PMID:26995618

  4. Energy efficient of ethanol recovery in pervaporation membrane bioreactor with mechanical vapor compression eliminating the cold traps.

    PubMed

    Fan, Senqing; Xiao, Zeyi; Li, Minghai

    2016-07-01

    An energy efficient pervaporation membrane bioreactor with mechanical vapor compression was developed for ethanol recovery during the process of fermentation coupled with pervaporation. Part of the permeate vapor at the membrane downstream under the vacuum condition was condensed by running water at the first condenser and the non-condensed vapor enriched with ethanol was compressed to the atmospheric pressure and pumped into the second condenser, where the vapor was easily condensed into a liquid by air. Three runs of fermentation-pervaporation experiment have been carried out lasting for 192h, 264h and 360h respectively. Complete vapor recovery validated the novel pervaporation membrane bioreactor. The total flux of the polydimethylsiloxane (PDMS) membrane was in the range of 350gm(-2)h(-1) and 600gm(-2)h(-1). Compared with the traditional cold traps condensation, mechanical vapor compression behaved a dominant energy saving feature.

  5. Dynamic mechanical response of magnesium single crystal under compression loading: Experiments, model, and simulations

    NASA Astrophysics Data System (ADS)

    Li, Qizhen

    2011-05-01

    Magnesium single crystal samples are compressed at room temperature under quasistatic (˜0.001 s-1) loading in a universal testing machine and dynamic (430, 1000, and 1200 s-1) loading in a split Hopkinson pressure bar system. Stress-strain curves show that (a) the fracture strain slightly increases with the strain rate; and (b) the maximum strength and strain hardening rate increase significantly when the testing changes from quasistatic to dynamic, although they do not vary much when the strain rate for dynamic testing varies in the range of 430-1200 s-1. The operation of the secondary pyramidal slip system is the dominating deformation mechanism, which leads to a fracture surface with an angle of ˜42° with respect to the loading axial direction. A theoretical material model based on Johnson-Cook law is also derived. The model includes the strain hardening and strain rate hardening terms, and provides the stress-strain relations matching with the experimental results. Finite element simulations for the strain rates used in the experiments predict the mechanical responses of the material that agree well with the experimental data.

  6. Compressive mapping of number to space reflects dynamic encoding mechanisms, not static logarithmic transform

    PubMed Central

    Cicchini, Guido Marco; Anobile, Giovanni; Burr, David C.

    2014-01-01

    The mapping of number onto space is fundamental to measurement and mathematics. However, the mapping of young children, unschooled adults, and adults under attentional load shows strong compressive nonlinearities, thought to reflect intrinsic logarithmic encoding mechanisms, which are later “linearized” by education. Here we advance and test an alternative explanation: that the nonlinearity results from adaptive mechanisms incorporating the statistics of recent stimuli. This theory predicts that the response to the current trial should depend on the magnitude of the previous trial, whereas a static logarithmic nonlinearity predicts trialwise independence. We found a strong and highly significant relationship between numberline mapping of the current trial and the magnitude of the previous trial, in both adults and school children, with the current response influenced by up to 15% of the previous trial value. The dependency is sufficient to account for the shape of the numberline, without requiring logarithmic transform. We show that this dynamic strategy results in a reduction of reproduction error, and hence improvement in accuracy. PMID:24821771

  7. Axially compressed buckling of an embedded boron nitride nanotube subjected to thermo-electro-mechanical loadings

    NASA Astrophysics Data System (ADS)

    Salehi-Khojin, Amin; Jalili, Nader

    2007-04-01

    Unlike widely-used carbon nanotubes, boron nitride nanotubes (BNNTs) have shown to possess stable semiconducting behavior and strong piezoelectricity. Such properties along with their outstanding mechanical properties and thermal conductivity, make BNNTs promising candidate reinforcement materials for a verity of applications especially nanoelectronic and nanophotonic devices. Motivated by these abilities, we aim to study the buckling behavior of BNNT-reinforced piezoelectric polymeric composites when subjected to combined electro-thermo-mechanical loadings. For this, the multi-walled structure of BNNT is considered as elastic media and a set of concentric cylindrical shell with van der Waals interaction between them. Using three-dimensional equilibrium equations, Donnell shell theory is utilized to show that the axially compressive resistance of BNNT varies with applying thermal and electrical loads. The effect of BNNT piezoelectric property on the buckling behavior of the composites is demonstrated. More specifically, it is shown that applying direct and reverse voltages to BNNT changes the buckling loads for any axial and circumferential wavenumbers. Such capability could be uniquely utilized when designing BNNT-reinforced composites.

  8. Characterisation of the mechanical properties of infarcted myocardium in the rat under biaxial tension and uniaxial compression.

    PubMed

    Sirry, Mazin S; Butler, J Ryan; Patnaik, Sourav S; Brazile, Bryn; Bertucci, Robbin; Claude, Andrew; McLaughlin, Ron; Davies, Neil H; Liao, Jun; Franz, Thomas

    2016-10-01

    Understanding the passive mechanical properties of infarcted tissue at different healing stages is essential to explore the emerging biomaterial injection-based therapy for myocardial infarction (MI). Although rats have been widely used as animal models in such investigations, the data in literature that quantify the passive mechanical properties of rat heart infarcts is very limited. MI was induced in rats and hearts were harvested immediately (0 day), 7, 14 and 28 days after infarction onset. Left ventricle anterioapical samples were cut and underwent equibiaxial and non equibiaxial tension followed by uniaxial compression mechanical tests. Histological analysis was conducted to confirm MI and to quantify the size of the induced infarcts. Infarcts maintained anisotropy and the nonlinear biaxial and compressive mechanical behaviour throughout the healing phases with the circumferential direction being stiffer than the longitudinal direction. Mechanical coupling was observed between the two axes in all infarct groups. The 0, 7, 14 and 28 days infarcts showed 438, 693, 1048 and 1218kPa circumferential tensile moduli. The 28 day infarct group showed a significantly higher compressive modulus compared to the other infarct groups (p=0.0060, 0.0293, and 0.0268 for 0, 7 and 14 days groups). Collagen fibres were found to align in a preferred direction for all infarct groups supporting the observed mechanical anisotropy. The presented data are useful for developing material models for healing infarcts and for setting a baseline for future assessment of emerging mechanical-based MI therapies.

  9. Characterisation of the mechanical properties of infarcted myocardium in the rat under biaxial tension and uniaxial compression.

    PubMed

    Sirry, Mazin S; Butler, J Ryan; Patnaik, Sourav S; Brazile, Bryn; Bertucci, Robbin; Claude, Andrew; McLaughlin, Ron; Davies, Neil H; Liao, Jun; Franz, Thomas

    2016-10-01

    Understanding the passive mechanical properties of infarcted tissue at different healing stages is essential to explore the emerging biomaterial injection-based therapy for myocardial infarction (MI). Although rats have been widely used as animal models in such investigations, the data in literature that quantify the passive mechanical properties of rat heart infarcts is very limited. MI was induced in rats and hearts were harvested immediately (0 day), 7, 14 and 28 days after infarction onset. Left ventricle anterioapical samples were cut and underwent equibiaxial and non equibiaxial tension followed by uniaxial compression mechanical tests. Histological analysis was conducted to confirm MI and to quantify the size of the induced infarcts. Infarcts maintained anisotropy and the nonlinear biaxial and compressive mechanical behaviour throughout the healing phases with the circumferential direction being stiffer than the longitudinal direction. Mechanical coupling was observed between the two axes in all infarct groups. The 0, 7, 14 and 28 days infarcts showed 438, 693, 1048 and 1218kPa circumferential tensile moduli. The 28 day infarct group showed a significantly higher compressive modulus compared to the other infarct groups (p=0.0060, 0.0293, and 0.0268 for 0, 7 and 14 days groups). Collagen fibres were found to align in a preferred direction for all infarct groups supporting the observed mechanical anisotropy. The presented data are useful for developing material models for healing infarcts and for setting a baseline for future assessment of emerging mechanical-based MI therapies. PMID:27434651

  10. Atomistic modeling of structure II gas hydrate mechanics: Compressibility and equations of state

    NASA Astrophysics Data System (ADS)

    Vlasic, Thomas M.; Servio, Phillip; Rey, Alejandro D.

    2016-08-01

    This work uses density functional theory (DFT) to investigate the poorly characterized structure II gas hydrates, for various guests (empty, propane, butane, ethane-methane, propane-methane), at the atomistic scale to determine key structure and mechanical properties such as equilibrium lattice volume and bulk modulus. Several equations of state (EOS) for solids (Murnaghan, Birch-Murnaghan, Vinet, Liu) were fitted to energy-volume curves resulting from structure optimization simulations. These EOS, which can be used to characterize the compressional behaviour of gas hydrates, were evaluated in terms of their robustness. The three-parameter Vinet EOS was found to perform just as well if not better than the four-parameter Liu EOS, over the pressure range in this study. As expected, the Murnaghan EOS proved to be the least robust. Furthermore, the equilibrium lattice volumes were found to increase with guest size, with double-guest hydrates showing a larger increase than single-guest hydrates, which has significant implications for the widely used van der Waals and Platteeuw thermodynamic model for gas hydrates. Also, hydrogen bonds prove to be the most likely factor contributing to the resistance of gas hydrates to compression; bulk modulus was found to increase linearly with hydrogen bond density, resulting in a relationship that could be used predictively to determine the bulk modulus of various structure II gas hydrates. Taken together, these results fill a long existing gap in the material chemical physics of these important clathrates.

  11. A Biphasic Multiscale Study of the Mechanical Microenvironment of Chondrocytes within Articular Cartilage under Unconfined Compression

    PubMed Central

    Guo, Hongqiang; Maher, Suzanne A.; Torzilli, Peter A.

    2014-01-01

    Computational analyses have been used to study the biomechanical microenvironment of the chondrocyte that cannot be assessed by in vitro experimental studies; yet all computational studies thus far have focused on the effect of zonal location (superficial, middle, and deep) on the mechanical microenvironment of chondrocytes. The aim of this paper was to study the effect of both zonal and radial locations on the biomechanical microenvironment of chondrocytes in inhomogeneous cartilage under unconfined stress relaxation. A biphasic multiscale approach was employed and nine chondrocytes in different locations were studied. Hyperelastic biphasic theory and depth-dependent aggregate modulus and permeability of articular cartilage were included in the models. It was found that both zonal and radial locations affected the biomechanical stresses and strains of the chondrocytes. Chondrocytes in the mid-radial location had increased volume during the early stage of the loading process. Maximum principal shear stress at the interface between the chondrocyte and the extracellular matrix (ECM) increased with depth, yet that at the ECM-pericellular matrix (PCM) interface had an inverse trend. Fluid pressure decreased with depth, while the fluid pressure difference between the top and bottom boundaries of the microscale model increased with depth. Regardless of location, fluid was exchanged between the chondrocyte, PCM, and ECM. These findings suggested that even under simple compressive loading conditions, the biomechanical microenvironment of the chondrocytes, PCM and ECM were spatially dependent. The current study provides new insight on chondrocyte biomechanics. PMID:24882738

  12. Musculoskeletal chest wall pain

    PubMed Central

    Fam, Adel G.; Smythe, Hugh A.

    1985-01-01

    The musculoskeletal structures of the thoracic wall and the neck are a relatively common source of chest pain. Pain arising from these structures is often mistaken for angina pectoris, pleurisy or other serious disorders. In this article the clinical features, pathogenesis and management of the various musculoskeletal chest wall disorders are discussed. The more common causes are costochondritis, traumatic muscle pain, trauma to the chest wall, “fibrositis” syndrome, referred pain, psychogenic regional pain syndrome, and arthritis involving articulations of the sternum, ribs and thoracic spine. Careful analysis of the history, physical findings and results of investigation is essential for precise diagnosis and effective treatment. ImagesFig. 3Fig. 4Fig. 5 PMID:4027804

  13. Fainting After Chest Pain

    PubMed Central

    Wang, Ko-Fan; Chang, Chun-Chin; Hsu, Chien-Yi; Lee, Ching-Wei; Lin, Chung-Hsing; Chiang, Chern-En

    2015-01-01

    Variant angina presenting acute chest pain and ST elevation on electrocardiogram accounts for an underdiagnosed scenario in acute coronary syndrome and contributes to syncope as a consequence of ventricular arrhythmia. Here, we report a case of a 48-year-old man with a recent onset of chest pain and palpitations followed by syncope. Holter monitoring documented 2 episodes of evolving ST elevation associated with non-sustained ventricular tachycardia. Emergent cardiac catheterization indicated insignificant coronary narrowing. A non-invasive brachial artery ultrasound, which demonstrated endothelial dysfunction that was salvaged by exogenic nitrate, was used instead of intracoronary provocation. There was no clinical or electrocardiographic recurrence of variant angina after vasodilator treatment. In conclusion, variant angina represents an important but overlooked etiology for syncope. Holter monitoring facilitates the diagnostic and prognostic assessment in patients with syncope precipitated by chest pain. PMID:27122877

  14. Strain softening mechanism at meso scale during micro-compression in an ultrafine-grained pure copper

    SciTech Connect

    Xu, Jie; Li, Jianwei; Shan, Debin; Guo, Bin

    2015-09-15

    Strain softening behavior has been found at meso scale using micro-compression testing in an ultrafine-grained (UFG) pure copper by comparison with the typical strain hardening in conventional coarse-grained (CG) material. Microstructural observations show that grain size remains nearly the same including the fraction of high-angle grain boundaries during micro-compression in UFG pure copper. The Kernel average misorientation(KAM) distribution measured by electron backscatter diffraction (EBSD), as a statistical method, is applied to qualitatively evaluate dislocation density in the interior of the grains. It is suggested that the deformation mechanisms are dominated by grain boundary sliding and grain rotation accompanied by dislocation slip in UFG pure copper, which demonstrates that the strain softening behavior is primarily caused by dislocation annihilation during micro-compression.

  15. Chest neoplasms with infectious etiologies.

    PubMed

    Restrepo, Carlos S; Chen, Melissa M; Martinez-Jimenez, Santiago; Carrillo, Jorge; Restrepo, Catalina

    2011-12-28

    A wide spectrum of thoracic tumors have known or suspected viral etiologies. Oncogenic viruses can be classified by the type of genomic material they contain. Neoplastic conditions found to have viral etiologies include post-transplant lymphoproliferative disease, lymphoid granulomatosis, Kaposi's sarcoma, Castleman's disease, recurrent respiratory papillomatosis, lung cancer, malignant mesothelioma, leukemia and lymphomas. Viruses involved in these conditions include Epstein-Barr virus, human herpes virus 8, human papillomavirus, Simian virus 40, human immunodeficiency virus, and Human T-lymphotropic virus. Imaging findings, epidemiology and mechanism of transmission for these diseases are reviewed in detail to gain a more thorough appreciation of disease pathophysiology for the chest radiologist.

  16. A Review of Esophageal Chest Pain

    PubMed Central

    Coss-Adame, Enrique

    2015-01-01

    Noncardiac chest pain is a term that encompasses all causes of chest pain after a cardiac source has been excluded. This article focuses on esophageal sources for chest pain. Esophageal chest pain (ECP) is common, affects quality of life, and carries a substantial health care burden. The lack of a systematic approach toward the diagnosis and treatment of ECP has led to significant disability and increased health care costs for this condition. Identifying the underlying cause(s) or mechanism(s) for chest pain is key for its successful management. Common etiologies include gastroesophageal reflux disease, esophageal hypersensitivity, dysmotility, and psychological conditions, including panic disorder and anxiety. However, the pathophysiology of this condition is not yet fully understood. Randomized controlled trials have shown that proton pump inhibitor therapy (either omeprazole, lansoprazole, or rabeprazole) can be effective. Evidence for the use of antidepressants and the adenosine receptor antagonist theophylline is fair. Psychological treatments, notably cognitive behavioral therapy, may be useful in select patients. Surgery is not recommended. There remains a large unmet need for identifying the phenotype and prevalence of pathophysiologic mechanisms of ECP as well as for well-designed multicenter clinical trials of current and novel therapies. PMID:27134590

  17. Effects of Compressive Force, Particle Size and Moisture Content on Mechanical Properties of Biomass Grinds

    SciTech Connect

    Mani, Sudhagar; Tabil, Lope Jr.; Sokhansanj, Shahabaddine

    2006-03-01

    Chemical composition, moisture content, bulk and particle densities, and geometric mean particle size were determined to characterize grinds from wheat and barley straws, corn stover and switchgrass. The biomass grinds were compressed for five levels of compressive forces (1000, 2000, 3000, 4000, 4400 N) and three levels of particle sizes (3.2, 1.6 and 0.8 mm) at two levels of moisture contents (12% and 15% (wb) to establish the compression and relaxation data. Corn stover grind produced the highest compact density at low pressure during compression. Compressive force, particle size and moisture content of grinds significantly affected the compact density of barley straw, corn stover and switchgrass grinds. However, different particle sizes of wheat straw grind did not produce any significant difference on compact density. Barley straw grind had the highest asymptotic modulus among all other biomass grinds indicating that compact from barley straw grind were more rigid than those of other compacts. Asymptotic modulus increased with an increase in maximum compressive pressure. The trend of increase in asymptotic modulus (EA) with the maximum compressive pressure ( 0) was fitted to a second order polynomial equation. Keywords: Biomass grinds, chemical composition, compact density and asymptotic modulus

  18. In vitro evaluation of an external compression device for fontan mechanical assistance.

    PubMed

    Valdovinos, John; Shkolyar, Eugene; Carman, Gregory P; Levi, Daniel S

    2014-03-01

    While Fontan palliation in the form of the total cavopulmonary connection has improved the management of congenital single ventricle physiology, long-term outcomes for patients with this disease are suboptimal due to the lack of two functional ventricles. Researchers have shown that ventricular assist devices (VADs) can normalize Fontan hemodynamics. To minimize blood contacting surfaces of the VAD, we evaluated the use of an external compression device (C-Pulse Heart Assist System, Sunshine Heart Inc.) as a Fontan assist device. A mock circulation was developed to mimic the hemodynamics of a hypertensive Fontan circulation in a pediatric patient. The Sunshine C-Pulse compression cuff was coupled with polymeric valves and a compressible tube to provide nonblood-contacting pulsatile flow through the Fontan circulation. The effect of the number, one or two, and placement of valves, before or after the compression cuff, on inferior vena cava pressure (IVCP) was studied. In addition, the effect of device inflation volume and compression rate on maintaining low IVCP was investigated. With one valve located before the cuff, the device was unable to maintain an IVCP below 15.5 mm Hg. With two valves, the C-Pulse was able to maintain IVCP as low as 8.5 mm Hg. The C-Pulse provided pulsatile flow and pressure through the pulmonary branch of the mock circulation with a pulse pressure of 16 mm Hg and 180 mL/min additional flow above unassisted flow. C-Pulse compression reduced IVCP below 12 mm Hg with 13 cc inflation volume and compression rates above 105 bpm. This application of an external compression device combined with two valves has potential for use as an artificial right ventricle by maintaining low IVCP and providing pulsatile flow through the lungs.

  19. Solid-extracellular fluid interaction and damage in the mechanical response of rat brain tissue under confined compression.

    PubMed

    Haslach, Henry W; Leahy, Lauren N; Riley, Peter; Gullapalli, Rao; Xu, Su; Hsieh, Adam H

    2014-01-01

    The mechanical processes that underlie mild traumatic brain injury from physical insults are not well understood. One aspect in particular that has not been examined is the tissue fluid, which is known to be critical in the mechanical function of other organs. To investigate the contributions of solid-fluid interactions to brain tissue mechanics, we performed confined compression tests, that force the extracellular fluid (ECF) to flow in the direction of the deformation, on 6.35mm diameter, 3mm long cylindrical samples excised from various regions of rat brains. Two types of tests in deformation control, (1) quasi-static, slow and moderate constant strain rate tests at 0.64×10(-5)/s, 0.001/s and 1/s to large strains and (2) several applications of slow linear deformation to 5% strain each followed by stress relaxation are employed to explore the solid-fluid interaction. At slow and moderate compressive strain rates, we observed stress peaks in the applied strain range at about 11%, whose magnitudes exhibited statistically significant dependence on strain rate. These data suggest that the ECF carries load until the tissue is sufficiently damaged to permit pathological fluid flow. Under the slow ramp rate in the ramp-relaxation cycles protocol, commonly used to estimate permeability, the stress relaxes to zero after the first cycle, rather than to a non-zero equilibrium stress corresponding to the applied strain, which further implicates mechanical damage. Magnetic resonance imaging (MRI) of changes in tissue microstructure during confined compression, before and after compression, provides further evidence of tissue damage. The solid-fluid interactions, reflected in the morphology of the stress-stretch curves and supported by the MRI data, suggest that increases in hydrostatic pressure in the ECF may contribute to mechanical damage of brain tissue.

  20. Mechanical properties and shear failure surfaces of two alumina powders in triaxial compression

    SciTech Connect

    ZEUCH,DAVID H.; GRAZIER,J. MARK; ARGUELLO JR.,JOSE G.; EWSUK,KEVIN G.

    2000-04-24

    In the manufacture of ceramic components, near-net-shape parts are commonly formed by uniaxially pressing granulated powders in rigid dies. Density gradients that are introduced into a powder compact during press-forming often increase the cost of manufacturing, and can degrade the performance and reliability of the finished part. Finite element method (FEM) modeling can be used to predict powder compaction response, and can provide insight into the causes of density gradients in green powder compacts; however, accurate numerical simulations require accurate material properties and realistic constitutive laws. To support an effort to implement an advanced cap plasticity model within the finite element framework to realistically simulate powder compaction, the authors have undertaken a project to directly measure as many of the requisite powder properties for modeling as possible. A soil mechanics approach has been refined and used to measure the pressure dependent properties of ceramic powders up to 68.9 MPa (10,000 psi). Due to the large strains associated with compacting low bulk density ceramic powders, a two-stage process was developed to accurately determine the pressure-density relationship of a ceramic powder in hydrostatic compression, and the properties of that same powder compact under deviatoric loading at the same specific pressures. Using this approach, the seven parameters that are required for application of a modified Drucker-Prager cap plasticity model were determined directly. The details of the experimental techniques used to obtain the modeling parameters and the results for two different granulated alumina powders are presented.

  1. Chest Pain (Beyond the Basics)

    MedlinePlus

    ... coronary arteries. Heart attack — A heart attack, or myocardial infarction (MI), occurs when the surface covering of a ... chest pain Criteria for the diagnosis of acute myocardial infarction Outpatient evaluation of the adult with chest pain ...

  2. Sonography of the Pediatric Chest.

    PubMed

    Goh, Yonggeng; Kapur, Jeevesh

    2016-05-01

    Traditionally, pediatric chest diseases are evaluated with chest radiography. Due to advancements in technology, the use of sonography has broadened. It has now become an established radiation-free imaging tool that may supplement plain-film findings and, in certain cases, the first-line modality for evaluation of the pediatric chest. This pictorial essay will demonstrate the diagnostic potential of sonography, review a spectrum of pediatric chest conditions, and discuss their imaging features and clinical importance. PMID:27009313

  3. Prevalence of deep vein thrombosis and pulmonary embolism treated with mechanical compression device after total hip arthroplasty.

    PubMed

    Kim, Young-Hoo; Kulkarni, Sourabh S; Park, Jang-Won; Kim, Bom Sahn

    2015-04-01

    Several reports have suggested that there is a strikingly low prevalence of deep vein thrombosis (DVT) and pulmonary embolism (PE) after total hip arthroplasty (THA) in Asian patients. We determined the prevalence of DVT and PE after the use of a mechanical compression device only without pharmacological thromboprophylaxis in 459 patients (516 hips). The overall prevalence of DVT was 4.8% (27 of 561 hips). Nine of 27 hips had proximal thrombi. Three patients (0.7%) had asymptomatic PE. In our patients, combinations of absent thrombophilic polymorphisms with low clinical prothrombotic risk factors led to a low prevalence of DVT and virtually no symptomatic PE. Therefore, mechanical compression device only suffices to prevent DVT and PE in Asian patients.

  4. Prevalence of Deep Vein Thrombosis and Pulmonary Embolism Treated with Mechanical Compression Device After Total Knee Arthroplasty in Asian Patients.

    PubMed

    Kim, Young-Hoo; Kulkarni, Sourabh S; Park, Jang-Won; Kim, Jun-Shik

    2015-09-01

    The purpose of this study was: (1) to determine the prevalence of deep vein thrombosis (DVT) after the use of a mechanical compression device only, without pharmacological thromboprophylaxis; (2) to investigate the factors associated with DVT; and (3) to investigate the natural course of DVT and PE. We reviewed consecutive series of 874 patients (1434 knees) who received treatment with a mechanical compression device only for prevention of DVT after primary TKA. The prevalence of DVT was 6.6% (94 of 1434 knees). Proximal thrombi were found in 6 of 1434 knees (0.4%). No patient had PE on perfusion lung scans. Further sonograms and venograms for the patients with thrombi at 6 months after the operation revealed that all thrombi were resolved.

  5. Experimental approach and modelling of the mechanical behaviour of graphite fuel elements subjected to compression pulses

    NASA Astrophysics Data System (ADS)

    Forquin, P.

    2010-06-01

    Among the activities led by the Generation IV International Forum (GIF) relative to the future nuclear systems, the improvement of recycling of fuel elements and their components is a major issue. One of the studied systems by the GIF is the graphite-moderated high-temperature gas cooled reactor (HTGR). The fuel elements are composed of fuel roads half-inch in diameter named compacts. The compacts contain spherical particles made of actinide kernels about 500 m in diameter coated with three layers of carbon and silicon carbide, each about 50 m thick, dispersed in a graphite matrix. Recycling of compacts requires first a separation of triso-particles from the graphite matrix and secondly, the separation of the triso-coating from the kernels. This aim may be achieved by using pulsed currents: the compacts are placed within a cell filled by water and exposed to high voltage between 200 - 500 kV and discharge currents from 10 to 20 kA during short laps of time (about 2 µs) [1-2]. This repeated treatment leads to a progressive fragmentation of the graphite matrix and a disassembly of the compacts. In order to improve understanding of the fragmentation properties of compacts a series of quasi-static and dynamic experiments have been conducted with similar cylindrical samples containing 10% (volume fraction) of SiC particles coated in a graphite matrix. First, quasi-static compression tests have been performed to identify the mechanical behaviour of the material at low strain-rates (Fig.1). The experiments reveal a complex elasto-visco-plastic behaviour before a brittle failure. The mechanical response is characterised by a low yield stress (about 1 MPa), a strong strain-hardening in the loading phase and marked hysteresis-loops during unloading-reloading stages. Brittle failure is observed for axial stress about 13 MPa. In parallel, a series of flexural tests have been performed with the aim to characterise the quasi-static tensile strength of the particulate

  6. Comparative study of mechanical properties of dental restorative materials and dental hard tissues in compressive loads

    PubMed Central

    Lee, Jong Yeop

    2014-01-01

    There are two objectives. One is to show the differences in the mechanical properties of various dental restorative materials compared to those of enamel and dentin. The other is to ascertain which dental restorative materials are more suitable for clinical treatments. Amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy were processed as dental restorative material specimens. The specimens (width, height, and length of 1.2, 1.2, and 3.0 mm, respectively) were compressed at a constant loading speed of 0.1 mm/min. The maximum stress (115.0 ± 40.6, 55.0 ± 24.8, 291.2 ± 45.3, 274.6 ± 52.2, 2206.0 ± 522.9, and 953.4 ± 132.1 MPa), maximum strain (7.8% ± 0.5%, 4.0% ± 0.1%, 12.7% ± 0.8%, 32.8% ± 0.5%, 63.5% ± 14.0%, and 45.3% ± 7.4%), and elastic modulus (1437.5 ± 507.2, 1548.4 ± 583.5, 2323.4 ± 322.4, 833.1 ± 92.4, 3895.2 ± 202.9, and 2222.7 ± 277.6 MPa) were evident for amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy, respectively. The reference hardness value of amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy was 90, 420, 130–135, 86.6–124.2, 1250, and 349, respectively. Since enamel grinds food, its abrasion resistance is important. Therefore, hardness value should be prioritized for enamel. Since dentin absorbs bite forces, mechanical properties should be prioritized for dentin. The results suggest that gold alloy simultaneously has a hardness value lower than enamel (74.8 ± 18.1), which is important in the wear of the opposing natural teeth, and higher maximum stress, maximum strain, and elastic modulus than dentin (193.7 ± 30.6 MPa, 11.9% ± 0.1%, 1653.7 ± 277.9 MPa, respectively), which are important considering the rigidity to absorb bite forces. PMID:25352921

  7. The Protective Effects of Salubrinal on the Cartilage and Subchondral Bone of the Temporomandibular Joint under Various Compressive Mechanical Stimulations

    PubMed Central

    Zhang, Caixia; Chen, Sheng; Li, Huang

    2016-01-01

    Excessive mechanical loads on the temporomandibular joint (TMJ) can cause mandibular cartilage degradation and subchondral bone erosion, but the treatment of these conditions remains challenging. Salubrinal, which target eukaryotic translation initiation factor 2 alpha, has been shown to have multiple beneficial effects on skeletal tissue. Here, we examined the effect of a Salubrinal injection on the mandibular cartilage and subchondral bone of the TMJ under various compressive stresses. We conducted in vivo analyses in rat models using various compressive stresses (40 g and 80 g), and we observed time-related degeneration and pathological changes in the cartilage and subchondral bone of the TMJ at days 1, 3 and 7 through histological measurements, subcellular observation, and changes in proliferation and apoptosis. After the Salubrinal injection, the thickness of the cartilage recovered, and the pathological change was alleviated. In the Salubrinal/light (Sal/light) compressive stress group, the drug altered the proliferation and apoptosis of chondrocytes most significantly at day 1. In the Salubrinal/heavy (Sal/heavy) compressive stress group, the drug increased the proliferation of chondrocytes most significantly at day 1 and reduced the apoptosis of chondrocytes most significantly at day 7. Salubrinal also increased the area of the bone trabeculae and suppressed inflammatory responses and pathological change in the subchondral bone of the TMJ. Together, these results indicate that the administration of Salubrinal reduces apoptosis and strengthens the proliferation of chondrocyte to varying degrees at days 1, 3 and 7 under various compressive mechanical stresses, both of which contribute to the recovery of cartilage thickness and the alleviation of pathological change. Salubrinal also suppresses inflammatory responses and pathological change in the subchondral bone of the TMJ. PMID:27196267

  8. The Protective Effects of Salubrinal on the Cartilage and Subchondral Bone of the Temporomandibular Joint under Various Compressive Mechanical Stimulations.

    PubMed

    Wen, Juan; Jiang, Yuanyuan; Zhang, Caixia; Chen, Sheng; Li, Huang

    2016-01-01

    Excessive mechanical loads on the temporomandibular joint (TMJ) can cause mandibular cartilage degradation and subchondral bone erosion, but the treatment of these conditions remains challenging. Salubrinal, which target eukaryotic translation initiation factor 2 alpha, has been shown to have multiple beneficial effects on skeletal tissue. Here, we examined the effect of a Salubrinal injection on the mandibular cartilage and subchondral bone of the TMJ under various compressive stresses. We conducted in vivo analyses in rat models using various compressive stresses (40 g and 80 g), and we observed time-related degeneration and pathological changes in the cartilage and subchondral bone of the TMJ at days 1, 3 and 7 through histological measurements, subcellular observation, and changes in proliferation and apoptosis. After the Salubrinal injection, the thickness of the cartilage recovered, and the pathological change was alleviated. In the Salubrinal/light (Sal/light) compressive stress group, the drug altered the proliferation and apoptosis of chondrocytes most significantly at day 1. In the Salubrinal/heavy (Sal/heavy) compressive stress group, the drug increased the proliferation of chondrocytes most significantly at day 1 and reduced the apoptosis of chondrocytes most significantly at day 7. Salubrinal also increased the area of the bone trabeculae and suppressed inflammatory responses and pathological change in the subchondral bone of the TMJ. Together, these results indicate that the administration of Salubrinal reduces apoptosis and strengthens the proliferation of chondrocyte to varying degrees at days 1, 3 and 7 under various compressive mechanical stresses, both of which contribute to the recovery of cartilage thickness and the alleviation of pathological change. Salubrinal also suppresses inflammatory responses and pathological change in the subchondral bone of the TMJ. PMID:27196267

  9. Induced sensitivity of Bacillus subtilis colony morphology to mechanical media compression

    PubMed Central

    Polka, Jessica K.

    2014-01-01

    Bacteria from several taxa, including Kurthia zopfii, Myxococcus xanthus, and Bacillus mycoides, have been reported to align growth of their colonies to small features on the surface of solid media, including anisotropies created by compression. While the function of this phenomenon is unclear, it may help organisms navigate on solid phases, such as soil. The origin of this behavior is also unknown: it may be biological (that is, dependent on components that sense the environment and regulate growth accordingly) or merely physical. Here we show that B. subtilis, an organism that typically does not respond to media compression, can be induced to do so with two simple and synergistic perturbations: a mutation that maintains cells in the swarming (chained) state, and the addition of EDTA to the growth media, which further increases chain length. EDTA apparently increases chain length by inducing defects in cell separation, as the treatment has only marginal effects on the length of individual cells. These results lead us to three conclusions. First, the wealth of genetic tools available to B. subtilis will provide a new, tractable chassis for engineering compression sensitive organisms. Second, the sensitivity of colony morphology to media compression in Bacillus can be modulated by altering a simple physical property of rod-shaped cells. And third, colony morphology under compression holds promise as a rapid, simple, and low-cost way to screen for changes in the length of rod-shaped cells or chains thereof. PMID:25289183

  10. Incidences of Deep Vein Thrombosis and Pulmonary Embolism after Total Knee Arthroplasty Using a Mechanical Compression Device with and without Low-Molecular-Weight Heparin

    PubMed Central

    Park, Sin Hyung; Ahn, Joong Hyeon; Park, Yong Bok; Lee, Sun Geun

    2016-01-01

    Purpose To investigate the incidence of thromboembolic events and complications related to bleeding after total knee arthroplasty (TKA) with a mechanical compression device alone or in combination with low-molecular-weight heparin (LMWH). Materials and Methods A total of 489 TKA patients (776 knees) were retrospectively reviewed for the incidence of thromboembolic events and complications related to bleeding. While 233 patients (354 knees) were treated with a mechanical compressive device without LMWH, 256 patients (422 knees) were treated with the mechanical compressive device along with LMWH. Results The incidences of deep vein thrombosis (DVT) and pulmonary embolism (PE) were 15 of 375 knees (4.0%) and 5 of 375 knees (1.3%), respectively, in the group that used only a mechanical compressive device, and 14 of 401 knees (3.4%) and 5 of 401 knees (1.2%), respectively, in the group that used the mechanical compressive device with LMWH. There was no significant difference between the two groups (p=0.125 and p=0.146, respectively). The postoperative hemovac drainage amount was 635±57 mL in the group with a mechanical compressive device only and 813±84 mL in the group with the device and LMWH; therefore, the amount of drainage was significantly greater in the latter group (p=0.013). Conclusions Mechanical compression alone for prophylaxis against DVT and PE after TKA can be an attractive option in Korean patients. PMID:27595075

  11. Incidences of Deep Vein Thrombosis and Pulmonary Embolism after Total Knee Arthroplasty Using a Mechanical Compression Device with and without Low-Molecular-Weight Heparin

    PubMed Central

    Park, Sin Hyung; Ahn, Joong Hyeon; Park, Yong Bok; Lee, Sun Geun

    2016-01-01

    Purpose To investigate the incidence of thromboembolic events and complications related to bleeding after total knee arthroplasty (TKA) with a mechanical compression device alone or in combination with low-molecular-weight heparin (LMWH). Materials and Methods A total of 489 TKA patients (776 knees) were retrospectively reviewed for the incidence of thromboembolic events and complications related to bleeding. While 233 patients (354 knees) were treated with a mechanical compressive device without LMWH, 256 patients (422 knees) were treated with the mechanical compressive device along with LMWH. Results The incidences of deep vein thrombosis (DVT) and pulmonary embolism (PE) were 15 of 375 knees (4.0%) and 5 of 375 knees (1.3%), respectively, in the group that used only a mechanical compressive device, and 14 of 401 knees (3.4%) and 5 of 401 knees (1.2%), respectively, in the group that used the mechanical compressive device with LMWH. There was no significant difference between the two groups (p=0.125 and p=0.146, respectively). The postoperative hemovac drainage amount was 635±57 mL in the group with a mechanical compressive device only and 813±84 mL in the group with the device and LMWH; therefore, the amount of drainage was significantly greater in the latter group (p=0.013). Conclusions Mechanical compression alone for prophylaxis against DVT and PE after TKA can be an attractive option in Korean patients.

  12. Effect of loading rate on the compressive mechanics of the immature baboon cervical spine.

    PubMed

    Elias, Paul Z; Nuckley, David J; Ching, Randal P

    2006-02-01

    Thirty-four cervical spine segments were harvested from 12 juvenile male baboons and compressed to failure at displacement rates of 5, 50, 500, or 5000 mm/s. Compressive stiffness, failure load, and failure displacement were measured for comparison across loading rate groups. Stiffness showed a significant concomitant increase with loading rate, increasing by 62% between rates of 5 and 5000 mm/s. Failure load also demonstrated an increasing relationship with loading rate, while displacement at failure showed no rate dependence. These data may help in the development of improved pediatric automotive safety standards and more biofidelic physical and computational models.

  13. Physical mechanism of anisotropic sensitivity in pentaerythritol tetranitrate from compressive-shear reaction dynamics simulations

    NASA Astrophysics Data System (ADS)

    Zybin, Sergey V.; Goddard, William A.; Xu, Peng; van Duin, Adri C. T.; Thompson, Aidan P.

    2010-02-01

    We propose computational protocol (compressive shear reactive dynamics) utilizing the ReaxFF reactive force field to study chemical initiation under combined shear and compressive load. We apply it to predict the anisotropic initiation sensitivity observed experimentally for shocked pentaerythritol tetranitrate single crystals. For crystal directions known to be sensitive we find large stress overshoots and fast temperature increase that result in early bond-breaking processes whereas insensitive directions exhibit small stress overshoot, lower temperature increase, and little bond dissociation. These simulations confirm the model of steric hindrance to shear and capture the thermochemical processes dominating the phenomena of shear-induced chemical initiation.

  14. Bilateral mechanical and thermal hyperalgesia and tactile allodynia after chronic compression of dorsal root ganglion in mice.

    PubMed

    Chen, Rong-Gui; Kong, Wei-Wei; Ge, Da-Long; Luo, Ceng; Hu, San-Jue

    2011-08-01

    OBJECTIVE Low back pain is one of the most inextricable problems encountered in clinics. Animal models that imitate symptoms in humans are valuable tools for investigating low back pain mechanisms and the possible therapeutic applications. With the development of genetic technology in pain field, the possibility of mutating specific genes in mice has provided a potent tool for investigating the specific mechanisms of pain. The aim of the present study was to develop a mouse model of chronic compression of dorsal root ganglion (CCD), in which gene mutation can be applied to facilitate the studies of chronic pain. METHODS Chronic compression of L4 and L5 dorsal root ganglia was conducted in mice by inserting fine stainless steel rods into the intervertebral foramina, one at L4 and the other at L5. Mechanical allodynia and thermal hyperalgesia were examined with von Frey filaments and radiating heat stimulator, respectively. RESULTS The CCD mice displayed dramatic mechanical and thermal hyperalgesia as well as tactile allodynia in the hindpaw ipsilateral to CCD. In addition, this mechanical and thermal hyperalgesia as well as tactile allodynia was also found to spread to the contralateral hindpaw. CONCLUSION This model, combined with the possible genetic modification, will strengthen our knowledge of the underlying mechanisms of low back pain. It also favors the development of new treatment strategies for pain and hyperalgesia after spinal injury and other disorders which affect the dorsal root ganglion in humans. PMID:21788994

  15. [Acute Chest Pain].

    PubMed

    Gmür, Christian

    2016-02-17

    Acute chest pain is a frequent consultation reason in general practice as well as in emergency departments. With the help of history, physical examination, ECG, laboratory and newly developed risk scores, potentially life-threatening diseases and high-risk patients may be detected and treated early, quickly and cost-effectively. New biomarkers and their combination with risk scores can increase the negative predictive value to exclude certain diseases. PMID:26886697

  16. Effect of restorative technique and thermal/mechanical treatment on marginal adaptation and compressive strength of esthetic restorations.

    PubMed

    de Paula, Andréia Bolzan; Duque, Cristiane; Correr-Sobrinho, Lourenço; Puppin-Rontani, Regina M

    2008-01-01

    This study evaluated the compressive strength and marginal adaptation of composite onlays using indirect and direct techniques after thermal and mechanical cycling. Onlay standardized cavities were prepared in 50 permanent molars and restored with Z-250 resin composite using indirect (IRT) or direct (DRT) restorative techniques. The restorations were either submitted or not submitted to thermal (500 cycles, 5 degrees to 55 degrees C) and mechanical cycling (50,000 cycles, 50N). The teeth were distributed to five groups (n=10): G1-IRT/cycling; G2-IRT/no cycling; G3-DRT/cycling; G4-DRT/no cycling and G5 (control group)-sound teeth. All prepared teeth were stored in 100% relative humidity at 37 degrees C for 24 hours, followed by finishing with Sof-Lex discs. A caries detector solution was applied on the tooth-restoration interface of all teeth for five seconds, followed by washing and drying. Four digital photographs were taken of each tooth surface. The extent of gaps was measured using standard software (Image Tool 3.0). All groups were submitted to compression testing in a universal testing machine (INSTRON) at a crosshead speed of 1 mm/minute until failure. The compressive strength (CS) and marginal adaptation data were submitted to ANOVA and Tukey test (p<0.05). For both evaluation criteria (compressive strength and marginal adaptation), there were no statistically significant differences among the restorative techniques. Deterioration over time was observed for both types of restorations. However, the prevalence of catastrophic fractures increased among direct restorations. The application of thermal/mechanical cycling only influenced marginal adaptation.

  17. Numerical study of mechanical behavior of ceramic composites under compression loading in the framework of movable cellular automaton method

    SciTech Connect

    Konovalenko, Igor S. Smolin, Alexey Yu. Konovalenko, Ivan S.; Promakhov, Vladimir V.; Psakhie, Sergey G.

    2014-11-14

    Movable cellular automaton method was used for investigating the mechanical behavior of ceramic composites under uniaxial compression. A 2D numerical model of ceramic composites based on oxides of zirconium and aluminum with different structural parameters was developed using the SEM images of micro-sections of a real composite. The influence of such structural parameters as the geometrical dimensions of layers, inclusions, and their spatial distribution in the sample, the volume content of the composite components and their mechanical properties (as well as the amount of zirconium dioxide that underwent the phase transformation) on the fracture, strength, deformation and dissipative properties was investigated.

  18. Thermal Cycling and Degradation Mechanisms of Compressive Mica-based Seals for Solid Oxide Fuel Cells

    SciTech Connect

    Chou, Yeong-Shyung ); Stevenson, Jeffry W. )

    2002-11-14

    Thermal cycling was conducted on the compressive mica seals at 800 degrees C in air. Thin ({approx}0-1 mm) Muscovite mica was pressed between a metal pipe and an alumina substrate and tested for leak rates at a stress of 100 psi in the plain (mica only) and the hybrid design.

  19. The stove-in chest: a complex flail chest injury.

    PubMed

    Bloomer, Roger; Willett, Keith; Pallister, Ian

    2004-05-01

    The stove-in chest is a rare form of flail chest in which there is collapse of a segment of the chest wall, associated with a high immediate mortality. A 65-year-old male pedestrian was admitted with severe chest pain and dyspnoea, after being struck by a car. The initial chest radiograph demonstrated multiple right-sided rib fractures and pulmonary contusion. His gas exchange was good, and after pain relief via an epidural catheter was achieved, an intercostal drain was inserted into the right hemi-thorax. Clinically apparent deformation of the chest then occurred. A further chest radiograph confirmed the stove-in chest. The patient remained well initially, but on day 5 he deteriorated precipitously with respiratory failure, and signs of systemic sepsis. He died despite maximal ventilatory and inotropic support on the Intensive Care Unit (ICU). Post-mortem examination demonstrated congested, oedematous lungs with a right-sided empyema. The management of complex flail chest injuries requires treatment to be tailored to the individual patient. Early ventilatory support, despite good gas exchange, may have closed down the pleural space prevented the empyema. Prophylactic ventilation and possibly surgical stabilisation of the chest wall should be considered early in the course of admission, even when the conventional parameters to indicate ventilation are not met.

  20. Room Temperature Deformation Mechanisms of Alumina Particles Observed from In Situ Micro-compression and Atomistic Simulations

    NASA Astrophysics Data System (ADS)

    Sarobol, Pylin; Chandross, Michael; Carroll, Jay D.; Mook, William M.; Bufford, Daniel C.; Boyce, Brad L.; Hattar, Khalid; Kotula, Paul G.; Hall, Aaron C.

    2016-01-01

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containing numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. The identified deformation mechanisms provide insight into feedstock design for AD.

  1. Evaluation of Quantitative Magnetic Resonance Imaging, Biochemical and Mechanical Properties of Trypsin-Treated Intervertebral Discs Under Physiological Compression Loading

    PubMed Central

    Mwale, Fackson; Demers, Caroline N.; Michalek, Arthur J.; Beaudoin, Gilles; Goswami, Tapas; Beckman, Lorne; Iatridis, James C.; Antoniou, John

    2014-01-01

    Purpose To investigate the influence of targeted trypsin digestion and 16 hours compression loading on MR parameters and the mechanical and biochemical properties of bovine disc segments. Materials and Methods Twenty-two 3-disc bovine coccygeal segments underwent compression loading for 16 hours after the nucleus pulposus (NP) of each disc was injected with a solution of trypsin or buffer. The properties of the NP and annulus fibrosus (AF) tissues of each disc were analyzed by quantitative MRI, biochemical tests, and confined compression tests. Results Loading had a significant effect on the MR properties (T1, T2, T1ρ, MTR, ADC) of both the NP and AF tissues. Loading had a greater effect on the MR parameters and biochemical composition of the NP than trypsin. In contrast, trypsin had a larger effect on the mechanical properties. Our data also indicated that localized trypsin injection predominantly affected the NP. T1ρ was sensitive to loading and correlated with the water content of the NP and AF but not with their proteoglycan content. Conclusion Our studies indicate that physiological loading is an important parameter to consider and that T1ρ contributes new information in efforts to develop quantitative MRI as a noninvasive diagnostic tool to detect changes in early disc degeneration. PMID:18219615

  2. Room temperature deformation mechanisms of alumina particles observed from in situ micro-compression and atomistic simulations.

    SciTech Connect

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay D.; Mook, William M.; Bufford, Daniel Charles; Boyce, Brad L.; Hattar, Khalid Mikhiel; Kotula, Paul G.; Hall, Aaron Christopher

    2015-09-22

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containing numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. As a result, the identified deformation mechanisms provide insight into feedstock design for AD.

  3. Room temperature deformation mechanisms of alumina particles observed from in situ micro-compression and atomistic simulations.

    DOE PAGES

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay D.; Mook, William M.; Bufford, Daniel Charles; Boyce, Brad L.; Hattar, Khalid Mikhiel; Kotula, Paul G.; Hall, Aaron Christopher

    2015-09-22

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containingmore » numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. As a result, the identified deformation mechanisms provide insight into feedstock design for AD.« less

  4. Phase dependent restoration mechanisms of TC8 titanium alloy during hot compression in the two phase region

    NASA Astrophysics Data System (ADS)

    Wang, K.; Luan, B. F.; Li, M. Q.; Liu, Q.

    2015-08-01

    The TC8 titanium alloy was isothermally compressed at 1133 K and 1213 K in the (α+β) two phase region. The microstructural evolution and restoration mechanism in the α and β phases were characterized by optical microscopy and transmission electron microscopy. The results show a significant effect of phase content on the microstructural evolution and restoration mechanism. The grain refinement occurs in the α phase at both temperatures, but in the β phase only at the higher temperature of 1213 K. This difference in microstructural evolution is attributed to the different temperature dependence of restoration mechanisms in the two phases. A significant increase in the volume fraction of β phase makes the restoration mechanism in the β phase change from dynamic recovery (DRV) to dynamic recrystallization (DRX), which subsequently induces the β grain refinement.

  5. A variational principle for compressible fluid mechanics. Discussion of the one-dimensional theory

    NASA Technical Reports Server (NTRS)

    Prozan, R. J.

    1982-01-01

    The second law of thermodynamics is used as a variational statement to derive a numerical procedure to satisfy the governing equations of motion. The procedure, based on numerical experimentation, appears to be stable provided the CFL condition is satisfied. This stability is manifested no matter how severe the gradients (compression or expansion) are in the flow field. For reasons of simplicity only one dimensional inviscid compressible unsteady flow is discussed here; however, the concepts and techniques are not restricted to one dimension nor are they restricted to inviscid non-reacting flow. The solution here is explicit in time. Further study is required to determine the impact of the variational principle on implicit algorithms.

  6. Functional assessment of toad parotoid macroglands: a study based on poison replacement after mechanical compression.

    PubMed

    Jared, Simone G S; Jared, Carlos; Egami, Mizue I; Mailho-Fontana, Pedro L; Rodrigues, Miguel T; Antoniazzi, Marta M

    2014-09-01

    Toads have a pair of parotoid macroglands behind the eyes that secrete poison used in passive defence against predators. These macroglands are composed of juxtaposed alveoli, each one bearing a syncytial gland, all connected to the exterior by ducts. When the parotoids are bitten, the poison is expelled on the predator oral mucosa in the form of jets, causing several pharmacological actions. After poison release, the empty secretory syncytia immediately collapse in the interior of their respective alveoli and gradually start refilling. After parotoid manual compression, simulating a predator's bite, we studied, by means of morphological methods, the replacement of the poison inside the alveoli. The results showed that after compression, a considerable number of alveoli remained intact. In the alveoli that were effectively affected the recovery occurs in different levels, from total to punctual and often restrict to some areas of the syncytia. The severely affected alveoli seem not recover their original functional state. The fact that only a part of the parotoid alveoli is compressed during an attack seems to be crucial for toad survival, since the amphibian, after being bitten by a predator, do not lose all its poison stock, remaining protected in case of new attacks. PMID:24911375

  7. Functional assessment of toad parotoid macroglands: a study based on poison replacement after mechanical compression.

    PubMed

    Jared, Simone G S; Jared, Carlos; Egami, Mizue I; Mailho-Fontana, Pedro L; Rodrigues, Miguel T; Antoniazzi, Marta M

    2014-09-01

    Toads have a pair of parotoid macroglands behind the eyes that secrete poison used in passive defence against predators. These macroglands are composed of juxtaposed alveoli, each one bearing a syncytial gland, all connected to the exterior by ducts. When the parotoids are bitten, the poison is expelled on the predator oral mucosa in the form of jets, causing several pharmacological actions. After poison release, the empty secretory syncytia immediately collapse in the interior of their respective alveoli and gradually start refilling. After parotoid manual compression, simulating a predator's bite, we studied, by means of morphological methods, the replacement of the poison inside the alveoli. The results showed that after compression, a considerable number of alveoli remained intact. In the alveoli that were effectively affected the recovery occurs in different levels, from total to punctual and often restrict to some areas of the syncytia. The severely affected alveoli seem not recover their original functional state. The fact that only a part of the parotoid alveoli is compressed during an attack seems to be crucial for toad survival, since the amphibian, after being bitten by a predator, do not lose all its poison stock, remaining protected in case of new attacks.

  8. Deformation mechanisms of olivine single crystals compressed at 300 MPa and 800-1100°C

    NASA Astrophysics Data System (ADS)

    Cordier, Patrick; Demouchy, Sylvie; Mussi, Alexandre; Tommasi, Andrea

    2013-04-01

    Rheology of mantle rocks at lithospheric temperatures remains poorly constrained, since most experimental studies on creep mechanisms of olivine single crystals ((MgFe)2SiO4, Pbnm) and polycrystalline olivine aggregates were performed at high-temperatures (T >> 1200oC). In this study, we have performed deformation experiments on oriented single crystals of San Carlos olivine and polycrystalline olivine aggregate at temperatures relevant of the uppermost mantle (ranging from 800o to 1090oC) in tri-axial compression. The experiments were carried out at a confining pressure of 300 MPa in a high-resolution gas-medium mechanical testing apparatus at various constant strain rates (from 7 × 10-6 s-1 to 1 × 10-4 s-1). Mechanical tests yield differential stresses ranging from 88 to 1076 MPa. All samples were deformed at constant displacement rate and for finite strains ranging from 4 to 23 %, to provide insight into possible effects of hardening, softening or stick-and-slip. The single crystals were compressed along several crystallographic directions to test the possibility of activating different slip systems (e.g. [100](001), [001](100), [001](010) and [100](010)). We will present the characterization of the dislocation microstructures performed in the TEM.

  9. Microstructure and compressive mechanical properties of cortical bone in children with osteogenesis imperfecta treated with bisphosphonates compared with healthy children.

    PubMed

    Imbert, Laurianne; Aurégan, Jean-Charles; Pernelle, Kélig; Hoc, Thierry

    2015-06-01

    Osteogenesis imperfecta (OI) is a genetic disorder characterized by a change in bone tissue quality, but little data are available to describe the factors involved at the macroscopic scale. To better understand the effect of microstructure alterations on the mechanical properties at the sample scale, we studied the structural and mechanical properties of six cortical bone samples from children with OI treated with bisphosphonates and compared them to the properties of three controls. Scanning electron microscopy, high resolution computed tomography and compression testing were used to assess these properties. More resorption cavities and a higher osteocyte lacunar density were observed in OI bone compared with controls. Moreover, a higher porosity was measured for OI bones along with lower macroscopic Young's modulus, yield stress and ultimate stress. The microstructure was impaired in OI bones; the higher porosity and osteocyte lacunar density negatively impacted the mechanical properties and made the bone more prone to fracture.

  10. Compression creep rupture of an E-glass/vinyl ester composite subjected to combined mechanical and fire loading conditions

    NASA Astrophysics Data System (ADS)

    Boyd, Steven Earl

    Polymer matrix composites are seeing increasing use in structural systems (e.g. ships, bridges) and require a quantitative basis for describing their performance under combined mechanical load and fire. Although much work has been performed to characterize the flammability, fire resistance and toxicity of these composite systems, an understanding of the structural response of sandwich type structures and laminate panels under combined mechanical and thermal loads (simulating fire conditions) is still largely unavailable. Therefore a research effort to develop a model to describe the structural response of these glass/vinyl esters systems under fire loading conditions is relevant to the continuing and future application of polymer matrix composites aboard naval ships. The main goal of the effort presented here is to develop analytical models and finite element analysis methods and tools to predict limit states such as local compression failures due to micro-buckling, residual strength and times to failure for composite laminates at temperatures in the vicinity of the glass transition where failure is controlled by viscoelastic effects. Given the importance of compression loading to a structure subject to fire exposure, the goals of this work are succinctly stated as the: (a) Characterization of the non-linear viscoelastic and viscoplastic response of the E-glass/vinyl ester composite above Tg. (b) Description of the laminate compression mechanics as a function of stress and temperature including viscoelasticity. (c) Viscoelastic stress analysis of a laminated panel ([0/+45/90/-45/0] S) using classical lamination theory (CLT). Three manuscripts constitute this dissertation which is representative of the three steps listed above. First, a detailed characterization of the nonlinear thermoviscoelastic response of Vetrotex 324/Derakane 510A--40 through Tg was conducted using the Time--Temperature--Stress--Superposition Principle (TTSSP) and Zapas--Crissman model. Second

  11. Altered Knee Joint Mechanics in Simple Compression Associated with Early Cartilage Degeneration

    PubMed Central

    Dabiri, Y.; Li, L. P.

    2013-01-01

    The progression of osteoarthritis can be accompanied by depth-dependent changes in the properties of articular cartilage. The objective of the present study was to determine the subsequent alteration in the fluid pressurization in the human knee using a three-dimensional computer model. Only a small compression in the femur-tibia direction was applied to avoid numerical difficulties. The material model for articular cartilages and menisci included fluid, fibrillar and nonfibrillar matrices as distinct constituents. The knee model consisted of distal femur, femoral cartilage, menisci, tibial cartilage, and proximal tibia. Cartilage degeneration was modeled in the high load-bearing region of the medial condyle of the femur with reduced fibrillar and nonfibrillar elastic properties and increased hydraulic permeability. Three case studies were implemented to simulate (1) the onset of cartilage degeneration from the superficial zone, (2) the progression of cartilage degeneration to the middle zone, and (3) the progression of cartilage degeneration to the deep zone. As compared with a normal knee of the same compression, reduced fluid pressurization was observed in the degenerated knee. Furthermore, faster reduction in fluid pressure was observed with the onset of cartilage degeneration in the superficial zone and progression to the middle zone, as compared to progression to the deep zone. On the other hand, cartilage degeneration in any zone would reduce the fluid pressure in all three zones. The shear strains at the cartilage-bone interface were increased when cartilage degeneration was eventually advanced to the deep zone. The present study revealed, at the joint level, altered fluid pressurization and strains with the depth-wise cartilage degeneration. The results also indicated redistribution of stresses within the tissue and relocation of the loading between the tissue matrix and fluid pressure. These results may only be qualitatively interesting due to the small

  12. Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

    NASA Astrophysics Data System (ADS)

    Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong

    2016-06-01

    The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

  13. Dynamic characteristics and mechanisms of compressible metallic vapor plume behaviors in transient keyhole during deep penetration fiber laser welding

    NASA Astrophysics Data System (ADS)

    Pang, Shengyong; Shao, Xinyu; Li, Wen; Chen, Xin; Gong, Shuili

    2016-07-01

    The compressible metallic vapor plume or plasma plume behaviors in the keyhole during deep penetration laser welding have significant effects on the joint quality. However, these behaviors and their responses to process parameter variations have not been well understood. In this paper, we first systematically study the dynamic characteristics and mechanisms of compressible metallic vapor plume behaviors in transient keyhole during fiber laser welding of 304 stainless steels based on a multiple timescale multiphase model. The time-dependent temperature, pressure, velocity and Mach number distributions of vapor plume under different process parameters are theoretically predicted. It is found that the distributions of the main physical characteristics of vapor plume such as pressure, velocity as well as Mach number in keyhole are usually highly uneven and highly time dependent. The peak difference of the velocity, pressure, temperature and Mach number of the vapor plume in a keyhole could be greater than 200 m/s, 20 kPa, 1000 K and 0.6 Mach, respectively. The vapor plume characteristics in a transient keyhole can experience significant changes within several hundreds of nanoseconds. The formation mechanisms of these dynamic characteristics are mainly due to the mesoscale keyhole hump (sized in several tens of microns) dynamics. It is also demonstrated that it is possible to suppress the oscillations of compressible vapor plume in the keyhole by improving the keyhole stability through decreasing the heat input. However, stabilizing the keyhole could only weaken, but not eliminate, the observed highly uneven and transient characteristics. This finding may pose new challenges for accurate experimental measurements of vapor plume induced by laser welding.

  14. Melt-based compression-molded scaffolds from chitosan-polyester blends and composites: Morphology and mechanical properties.

    PubMed

    Correlo, V M; Boesel, L F; Pinho, E; Costa-Pinto, A R; Alves da Silva, M L; Bhattacharya, M; Mano, J F; Neves, N M; Reis, R L

    2009-11-01

    Blends of chitosan and synthetic aliphatic polyesters (polybutylene succinate, polybutylene succinate adipate, polycaprolactone, and polybutylene terepthalate adipate) were compounded with and without hydroxyapatite, a bioactive mineral filler known to enhance osteoconduction. The blends and composites were compression molded with two different granulometric salt sizes (63-125 microm and 250-500 microm) having different levels of salt content (60, 70, and 80%) by weight. By leaching the salt particles, it was possible to produce porous scaffolds with distinct morphologies. The relationship between scaffold morphology and mechanical properties was evaluated using scanning electron microscopy, microcomputed tomography, compression testing, differential scanning calorimetry, small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering. The produced scaffolds are characterized by having different morphologies depending on the average particle size and the amount of NaCl used. Specimens with higher porosity level have a less organized pore structure but increased interconnectivity of the pores. The stress-strain curve under compression displayed a linear elasticity followed by a plateau whose characteristics depend on the scaffold polymer composition. A decrease in the salt particle size used to create the porosity caused in general a decrease in the mechanical properties of the foams. Composites with hydroxyapatite had a sharp reduction in yield stress, modulus, and strain at break. The melting temperature decreased with increased chitosan content. SAXS results indicate no preferential crystalline orientation in the scaffolds. Cytotoxicity evaluation were carried out using standard tests (accordingly to ISO/EN 10993 part 5 guidelines), namely MTS test with a 24-h extraction period, revealing that L929 cells had comparable metabolic activities to that obtained for the negative control. PMID:18985771

  15. An experimental study on fracture mechanical behavior of rock-like materials containing two unparallel fissures under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Huang, Yan-Hua; Yang, Sheng-Qi; Tian, Wen-Ling; Zeng, Wei; Yu, Li-Yuan

    2016-06-01

    Strength and deformability characteristics of rock with pre-existing fissures are governed by cracking behavior. To further research the effects of pre-existing fissures on the mechanical properties and crack coalescence process, a series of uniaxial compression tests were carried out for rock-like material with two unparallel fissures. In the present study, cement, quartz sand, and water were used to fabricate a kind of brittle rock-like material cylindrical model specimen. The mechanical properties of rock-like material specimen used in this research were all in good agreement with the brittle rock materials. Two unparallel fissures (a horizontal fissure and an inclined fissure) were created by inserting steel during molding the model specimen. Then all the pre-fissured rock-like specimens were tested under uniaxial compression by a rock mechanics servo-controlled testing system. The peak strength and Young's modulus of pre-fissured specimen all first decreased and then increased when the fissure angle increased from 0° to 75°. In order to investigate the crack initiation, propagation and coalescence process, photographic monitoring was adopted to capture images during the entire deformation process. Moreover, acoustic emission (AE) monitoring technique was also used to obtain the AE evolution characteristic of pre-fissured specimen. The relationship between axial stress, AE events, and the crack coalescence process was set up: when a new crack was initiated or a crack coalescence occurred, the corresponding axial stress dropped in the axial stress-time curve and a big AE event could be observed simultaneously. Finally, the mechanism of crack propagation under microscopic observation was discussed. These experimental results are expected to increase the understanding of the strength failure behavior and the cracking mechanism of rock containing unparallel fissures.

  16. Chronic Compression of the Dorsal Root Ganglion Enhances Mechanically Evoked Pain Behavior and the Activity of Cutaneous Nociceptors in Mice

    PubMed Central

    Wang, Tao; Hurwitz, Olivia; Shimada, Steven G.; Qu, Lintao; Fu, Kai; Zhang, Pu; Ma, Chao; LaMotte, Robert H.

    2015-01-01

    Radicular pain in humans is usually caused by intraforaminal stenosis and other diseases affecting the spinal nerve, root, or dorsal root ganglion (DRG). Previous studies discovered that a chronic compression of the DRG (CCD) induced mechanical allodynia in rats and mice, with enhanced excitability of DRG neurons. We investigated whether CCD altered the pain-like behavior and also the responses of cutaneous nociceptors with unmyelinated axons (C-fibers) to a normally aversive punctate mechanical stimulus delivered to the hairy skin of the hind limb of the mouse. The incidence of a foot shaking evoked by indentation of the dorsum of foot with an aversive von Frey filament (tip diameter 200 μm, bending force 20 mN) was significantly higher in the foot ipsilateral to the CCD surgery as compared to the contralateral side on post-operative days 2 to 8. Mechanically-evoked action potentials were electrophysiologically recorded from the L3 DRG, in vivo, from cell bodies visually identified as expressing a transgenically labeled fluorescent marker (neurons expressing either the receptor MrgprA3 or MrgprD). After CCD, 26.7% of MrgprA3+ and 32.1% MrgprD+ neurons exhibited spontaneous activity (SA), while none of the unoperated control neurons had SA. MrgprA3+ and MrgprD+ neurons in the compressed DRG exhibited, in comparison with neurons from unoperated control mice, an increased response to the punctate mechanical stimuli for each force applied (6, 20, 40, and 80 mN). We conclude that CCD produced both a behavioral hyperalgesia and an enhanced response of cutaneous C-nociceptors to aversive punctate mechanical stimuli. PMID:26356638

  17. Static compressive strength prediction of open-hole structure based on non-linear shear behavior and micro-mechanics

    NASA Astrophysics Data System (ADS)

    Li, Wangnan; Cai, Hongneng; Li, Chao

    2014-11-01

    This paper deals with the characterization of the strength of the constituents of carbon fiber reinforced plastic laminate (CFRP), and a prediction of the static compressive strength of open-hole structure of polymer composites. The approach combined with non-linear analysis in macro-level and a linear elastic micromechanical failure analysis in microlevel (non-linear MMF) is proposed to improve the prediction accuracy. A face-centered cubic micromechanics model is constructed to analyze the stresses in fiber and matrix in microlevel. Non-interactive failure criteria are proposed to characterize the strength of fiber and matrix. The non-linear shear behavior of the laminate is studied experimentally, and a novel approach of cubic spline interpolation is used to capture significant non-linear shear behavior of laminate. The user-defined material subroutine UMAT for the non-linear share behavior is developed and combined in the mechanics analysis in the macro-level using the Abaqus Python codes. The failure mechanism and static strength of open-hole compressive (OHC) structure of polymer composites is studied based on non-linear MMF. The UTS50/E51 CFRP is used to demonstrate the application of theory of non-linear MMF.

  18. Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio

    NASA Technical Reports Server (NTRS)

    Wiesen, Bernard (Inventor)

    2008-01-01

    This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.

  19. Strength and Mechanical Response of NaCl Using In-Situ Transmission Electron Microscopy Compression and Nanoindentation.

    PubMed

    Lin, Kai-Peng; Fang, Te-Hua; Kang, Sho-Hui

    2016-03-01

    Strength and mechanical properties of single crystal sodium chloride (NaCl) are characterized. Critical deformation variations of NaCl pillared structures and films are estimated using in-situ transmission electron microscope (TEM) compression tests and nanoindentation experiments. Young's modulus and contact stiffness of NaCl pillars with diameters of 300 to 500 nm were 10.4-23.9 GPa, and 159-230 N/m, respectively. The nanohardness and Vickers hardness of the NaCl (001) film were 282-596 and 196-260 MPa, respectively. The results could provide useful information for understanding the mechanical properties, contact and local deformation of NaCl pillars and films. PMID:27455676

  20. Combining colloidal probe atomic force and reflection interference contrast microscopy to study the compressive mechanics of hyaluronan brushes.

    PubMed

    Attili, Seetharamaiah; Richter, Ralf P

    2012-02-14

    We describe a method that combines colloidal probe atomic force microscopy (AFM) and reflection interference contrast microscopy (RICM) to characterize the mechanical properties of thin and solvated polymer films. When analyzing polymer films, a fundamental problem in colloidal probe AFM experiments is to determine the distance at closest approach between the probe and the substrate on which the film is deposited. By combining AFM and RICM in situ, forces and absolute distances can be measured simultaneously. Using the combined setup, we quantify the compressive mechanics of films of the polysaccharide hyaluronan that is end-grafted to a supported lipid bilayer. The experimental data, and comparison with polymer theory, show that hyaluronan films are well-described as elastic, very soft and highly solvated polymer brushes. The data on these well-defined films should be a useful reference for the investigation of the more complex hyaluronan-rich coats that surround many living cells.

  1. Mechanical properties of GFRP tube confined recycled concrete under axial compression

    NASA Astrophysics Data System (ADS)

    Wang, Xiaogang; Liang, Chaofeng; Zhou, Zechenglong; Dong, Lanqi; Ding, Kewei; Huang, Jialun

    2015-07-01

    This article outlines the recycled aggregate replacement rate and thick-diameter rate of GFRP tube confined in recycled concrete, which has an important impact on the material's compressive strength. Overall, under the same conditions of using recycled concrete, the bearing capacity of short concrete columns can be improved by using broader GFRP tubes. There is a four-fold increase in the bearing capacity of short concrete columns compared to the short column without the restriction of a GFRP tube. The bearing capacity of a short column crafted by recycled coarse aggregate is much lower (about 30%). than those made by common concrete column Additionally, the bearing capacity of short columns made by recycled fine aggregates is also lower than those made by common concrete (approximately 20%). Finally, we find that there is no significant difference between experimental and theoretical data.

  2. Compressed gas manifold

    SciTech Connect

    Hildebrand, Richard J.; Wozniak, John J.

    2001-01-01

    A compressed gas storage cell interconnecting manifold including a thermally activated pressure relief device, a manual safety shut-off valve, and a port for connecting the compressed gas storage cells to a motor vehicle power source and to a refueling adapter. The manifold is mechanically and pneumatically connected to a compressed gas storage cell by a bolt including a gas passage therein.

  3. Experimental characterization and constitutive modeling of the mechanical behavior of molybdenum under electromagnetically applied compression-shear ramp loading

    NASA Astrophysics Data System (ADS)

    Alexander, C. S.; Ding, J. L.; Asay, J. R.

    2016-03-01

    Magnetically applied pressure-shear (MAPS) is a new experimental technique that provides a platform for direct measurement of material strength at extreme pressures. The technique employs an imposed quasi-static magnetic field and a pulsed power generator that produces an intense current on a planar driver panel, which in turn generates high amplitude magnetically induced longitudinal compression and transverse shear waves into a planar sample mounted on the drive panel. In order to apply sufficiently high shear traction to the test sample, a high strength material must be used for the drive panel. Molybdenum is a potential driver material for the MAPS experiment because of its high yield strength and sufficient electrical conductivity. To properly interpret the results and gain useful information from the experiments, it is critical to have a good understanding and a predictive capability of the mechanical response of the driver. In this work, the inelastic behavior of molybdenum under uniaxial compression and biaxial compression-shear ramp loading conditions is experimentally characterized. It is observed that an imposed uniaxial magnetic field ramped to approximately 10 T through a period of approximately 2500 μs and held near the peak for about 250 μs before being tested appears to anneal the molybdenum panel. In order to provide a physical basis for model development, a general theoretical framework that incorporates electromagnetic loading and the coupling between the imposed field and the inelasticity of molybdenum was developed. Based on this framework, a multi-axial continuum model for molybdenum under electromagnetic loading is presented. The model reasonably captures all of the material characteristics displayed by the experimental data obtained from various experimental configurations. In addition, data generated from shear loading provide invaluable information not only for validating but also for guiding the development of the material model for

  4. Experimental characterization and constitutive modeling of the mechanical behavior of molybdenum under electromagnetically applied compression-shear ramp loading

    DOE PAGES

    Alexander, C. Scott; Ding, Jow -Lian; Asay, James Russell

    2016-03-09

    Magnetically applied pressure-shear (MAPS) is a new experimental technique that provides a platform for direct measurement of material strength at extreme pressures. The technique employs an imposed quasi-static magnetic field and a pulsed power generator that produces an intense current on a planar driver panel, which in turn generates high amplitude magnetically induced longitudinal compression and transverse shear waves into a planar sample mounted on the drive panel. In order to apply sufficiently high shear traction to the test sample, a high strength material must be used for the drive panel. Molybdenum is a potential driver material for the MAPSmore » experiment because of its high yield strength and sufficient electrical conductivity. To properly interpret the results and gain useful information from the experiments, it is critical to have a good understanding and a predictive capability of the mechanical response of the driver. In this work, the inelastic behavior of molybdenum under uniaxial compression and biaxial compression-shear ramp loading conditions is experimentally characterized. It is observed that an imposed uniaxial magnetic field ramped to approximately 10 T through a period of approximately 2500 μs and held near the peak for about 250 μs before being tested appears to anneal the molybdenum panel. In order to provide a physical basis for model development, a general theoretical framework that incorporates electromagnetic loading and the coupling between the imposed field and the inelasticity of molybdenum was developed. Based on this framework, a multi-axial continuum model for molybdenum under electromagnetic loading is presented. The model reasonably captures all of the material characteristics displayed by the experimental data obtained from various experimental configurations. Additionally, data generated from shear loading provide invaluable information not only for validating but also for guiding the development of the material

  5. A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin.

    PubMed

    Leyva-Mendivil, Maria F; Page, Anton; Bressloff, Neil W; Limbert, Georges

    2015-09-01

    The study of skin biophysics has largely been driven by consumer goods, biomedical and cosmetic industries which aim to design products that efficiently interact with the skin and/or modify its biophysical properties for health or cosmetic benefits. The skin is a hierarchical biological structure featuring several layers with their own distinct geometry and mechanical properties. Up to now, no computational models of the skin have simultaneously accounted for these geometrical and material characteristics to study their complex biomechanical interactions under particular macroscopic deformation modes. The goal of this study was, therefore, to develop a robust methodology combining histological sections of human skin, image-processing and finite element techniques to address fundamental questions about skin mechanics and, more particularly, about how macroscopic strains are transmitted and modulated through the epidermis and dermis. The work hypothesis was that, as skin deforms under macroscopic loads, the stratum corneum does not experience significant strains but rather folds/unfolds during skin extension/compression. A sample of fresh human mid-back skin was processed for wax histology. Sections were stained and photographed by optical microscopy. The multiple images were stitched together to produce a larger region of interest and segmented to extract the geometry of the stratum corneum, viable epidermis and dermis. From the segmented structures a 2D finite element mesh of the skin composite model was created and geometrically non-linear plane-strain finite element analyses were conducted to study the sensitivity of the model to variations in mechanical properties. The hybrid experimental-computational methodology has offered valuable insights into the simulated mechanics of the skin, and that of the stratum corneum in particular, by providing qualitative and quantitative information on strain magnitude and distribution. Through a complex non-linear interplay

  6. Mechanical testing of hydrogels in cartilage tissue engineering: beyond the compressive modulus.

    PubMed

    Xiao, Yinghua; Friis, Elizabeth A; Gehrke, Stevin H; Detamore, Michael S

    2013-10-01

    Injuries to articular cartilage result in significant pain to patients and high medical costs. Unfortunately, cartilage repair strategies have been notoriously unreliable and/or complex. Biomaterial-based tissue-engineering strategies offer great promise, including the use of hydrogels to regenerate articular cartilage. Mechanical integrity is arguably the most important functional outcome of engineered cartilage, although mechanical testing of hydrogel-based constructs to date has focused primarily on deformation rather than failure properties. In addition to deformation testing, as the field of cartilage tissue engineering matures, this community will benefit from the addition of mechanical failure testing to outcome analyses, given the crucial clinical importance of the success of engineered constructs. However, there is a tremendous disparity in the methods used to evaluate mechanical failure of hydrogels and articular cartilage. In an effort to bridge the gap in mechanical testing methods of articular cartilage and hydrogels in cartilage regeneration, this review classifies the different toughness measurements for each. The urgency for identifying the common ground between these two disparate fields is high, as mechanical failure is ready to stand alongside stiffness as a functional design requirement. In comparing toughness measurement methods between hydrogels and cartilage, we recommend that the best option for evaluating mechanical failure of hydrogel-based constructs for cartilage tissue engineering may be tensile testing based on the single edge notch test, in part because specimen preparation is more straightforward and a related American Society for Testing and Materials (ASTM) standard can be adopted in a fracture mechanics context.

  7. Comparison of the Mechanical Characteristics of a Universal Small Biplane Plating Technique Without Compression Screw and Single Anatomic Plate With Compression Screw.

    PubMed

    Dayton, Paul; Ferguson, Joe; Hatch, Daniel; Santrock, Robert; Scanlan, Sean; Smith, Bret

    2016-01-01

    To better understand the mechanical characteristics of biplane locked plating in small bone fixation, the present study compared the stability under cyclic cantilever loading of a 2-plate locked biplane (BPP) construct without interfragmentary compression with that of a single-plate locked construct with an additional interfragmentary screw (SPS) using surrogate bone models simulating Lapidus arthrodesis. In static ultimate plantar bending, the BPP construct failed at significantly greater load than did the SPS construct (556.2 ± 37.1 N versus 241.6 ± 6.3 N, p = .007). For cyclic failure testing in plantar bending at a 180-N starting load, the BPP construct failed at a significantly greater number of cycles (158,322 ± 50,609 versus 13,718 ± 10,471 cycles) and failure load (242.5 ± 25.0 N versus 180.0 ± 0.0 N) than the SPS construct (p = .002). For cyclic failure testing in plantar bending at a 120-N starting load, the results were not significantly different between the BPP and SPS constructs for the number of cycles (207,646 ± 45,253 versus 159,334 ± 69,430) or failure load (205.0 ± 22.4 N versus 185.0 ± 33.5 N; p = .300). For cyclic testing with 90° offset loading (i.e., medial to lateral bending) at a 120-N starting load, all 5 BPP constructs (tension side) and 2 of the 5 SPS constructs reached 250,000 cycles without failure. Overall, the present study found the BPP construct to have superior or equivalent stability in multiplanar orientations of force application in both static and fatigue testing. Thus, the concept of biplane locked plating, using 2 low profile plates and unicortical screw insertion, shows promise in small bone fixation, because it provides consistent stability in multiplanar orientations, making it universally adaptable to many clinical situations.

  8. An elastically compressible phantom material with mechanical and x-ray attenuation properties equivalent to breast tissue

    NASA Astrophysics Data System (ADS)

    Price, B. D.; Gibson, A. P.; Tan, L. T.; Royle, G. J.

    2010-02-01

    We have developed a novel phantom material: a solution of polyvinyl alcohol (PVAL) in ethanol and water, freeze-thawed to produce a solid yet elastically compressible gel. The x-ray attenuation and mechanical properties of these gels are compared with published measurements of breast tissue. Gels with PVAL concentrations from 5 to 20% w/v were produced. The linear x-ray attenuation coefficients of these gels range from 0.76 to 0.86 cm-1 at 17.5 keV, increasing with PVAL concentration. These values are very similar to the published values of breast tissue at this energy, 0.8-0.9 cm-1. Under compression cancerous breast tissue is approximately ten times stiffer than healthy breast tissue. The Young's moduli of the gels increase with PVAL concentration. Varying the PVAL concentration from 7.5 to 20% w/v produces gels with Young's moduli from 20 to 220 kPa at 15% strain. These values are characteristic of normal and cancerous breast tissue, respectively.

  9. Surgical stabilisation in a 13-year-old boy with traumatic flail chest.

    PubMed

    Leenstra, Bernard Simon; Stolwijk, Antoinette; Poeze, Martijn

    2015-01-01

    Flail chest after blunt trauma to the chest has a high morbidity and mortality rate. Traumatic flail chest in children rarely occurs due to flexibility of the ribcage. We describe the case of a 13-year-old boy sustaining a flail chest after a high-energy trauma. Conservative treatment with proper mechanical ventilation and pain management was unsuccessful, and was followed by operative rib fixation. The patient was discharged home 17 days after surgery and, at 4 months follow-up, had fully recovered. This case report shows the possibility of operative rib fixation as treatment for flail chest in children. PMID:26370635

  10. Morphologic Interpretation of Rock Failure Mechanisms Under Uniaxial Compression Based on 3D Multiscale High-resolution Numerical Modeling

    NASA Astrophysics Data System (ADS)

    Li, Gen; Liang, Zheng-Zhao; Tang, Chun-An

    2015-11-01

    Multiscale continuous lab oratory observation of the progressive failure process has become a powerful means to reveal the complex failure mechanism of rock. Correspondingly, the representative volume element (RVE)-based models, which are capable of micro/meso- to macro-scale simulations, have been proposed, for instance, the rock failure process analysis (RFPA) program. Limited by the computational bottleneck due to the RVE size, multiscale high-resolution modeling of rock failure process can hardly be implemented, especially for three-dimensional (3D) problems. In this paper, the self-developed parallel RFPA3D code is employed to investigate the failure mechanisms and various fracture morphology of laboratory-scale rectangular prism rock specimens under unconfined uniaxial compression. The specimens consist of either heterogeneous rock with low strength or relatively homogeneous rock with high strength. The numerical simulations, such as the macroscopic fracture pattern and stress-strain responses, can reproduce the well-known phenomena of physical experiments. In particular, the 3D multiscale continuum modeling is carried out to gain new insight into the morphologic interpretation of brittle failure mechanisms, which is calibrated and validated by comparing the actual laboratory experiments and field evidence. The advantages of 3D multiscale high-resolution modeling are demonstrated by comparing the failure modes against 2D numerical predictions by other models. The parallel RVE-based modeling tool in this paper can provide an alternative way to investigate the complicated failure mechanisms of rock.

  11. Mechanical Testing of Hydrogels in Cartilage Tissue Engineering: Beyond the Compressive Modulus

    PubMed Central

    Xiao, Yinghua; Friis, Elizabeth A.; Gehrke, Stevin H.

    2013-01-01

    Injuries to articular cartilage result in significant pain to patients and high medical costs. Unfortunately, cartilage repair strategies have been notoriously unreliable and/or complex. Biomaterial-based tissue-engineering strategies offer great promise, including the use of hydrogels to regenerate articular cartilage. Mechanical integrity is arguably the most important functional outcome of engineered cartilage, although mechanical testing of hydrogel-based constructs to date has focused primarily on deformation rather than failure properties. In addition to deformation testing, as the field of cartilage tissue engineering matures, this community will benefit from the addition of mechanical failure testing to outcome analyses, given the crucial clinical importance of the success of engineered constructs. However, there is a tremendous disparity in the methods used to evaluate mechanical failure of hydrogels and articular cartilage. In an effort to bridge the gap in mechanical testing methods of articular cartilage and hydrogels in cartilage regeneration, this review classifies the different toughness measurements for each. The urgency for identifying the common ground between these two disparate fields is high, as mechanical failure is ready to stand alongside stiffness as a functional design requirement. In comparing toughness measurement methods between hydrogels and cartilage, we recommend that the best option for evaluating mechanical failure of hydrogel-based constructs for cartilage tissue engineering may be tensile testing based on the single edge notch test, in part because specimen preparation is more straightforward and a related American Society for Testing and Materials (ASTM) standard can be adopted in a fracture mechanics context. PMID:23448091

  12. Measurement of chest wall displacement based on terahertz wave

    NASA Astrophysics Data System (ADS)

    Li, Hui; Lv, Hao; Jiao, Teng; Lu, Guohua; Li, Sheng; Li, Zhao; Liu, Miao; Jing, Xijing; Wang, Jianqi

    2015-02-01

    Measurement of chest wall displacement is an important approach for measuring mechanics of chest wall, which has considerable significance for assessing respiratory system and diagnosing pulmonary diseases. However, existing optical methods for measuring chest wall displacement are inconvenient for some specific patients such as the female patients and the patients with bandaged chest. In this letter, we proposed a method for measuring chest wall displacement based on terahertz wave and established corresponding mathematic model and set up a terahertz measurement system. The main advantages of this method are that it can measure the chest wall displacement of the subjects without taking off clothes or arranging any markers. To validate this method and assess the performance of the terahertz system, in vitro, the displacement of a water module driven by a linear guide rail was measured by the terahertz system and compared with the actual displacement of the water module. The results showed that the waveforms measured with two methods have a good agreement, and the relative error is less than 5% and sufficiently good for measurement demands. In vivo, the synchronous experiment was performed on five human volunteers with the terahertz system and a respiratory belt transducer. The results demonstrate that this method has good performance and promising prospects for measuring chest wall displacement.

  13. Mechanical Properties and Microstructure of the CoCrFeMnNi High Entropy Alloy Under High Strain Rate Compression

    NASA Astrophysics Data System (ADS)

    Wang, Bingfeng; Fu, Ao; Huang, Xiaoxia; Liu, Bin; Liu, Yong; Li, Zezhou; Zan, Xiang

    2016-07-01

    The equiatomic CoCrFeMnNi high entropy alloy, which crystallizes in the face-centered cubic (FCC) crystal structure, was prepared by the spark plasma sintering technique. Dynamic compressive tests of the CoCrFeMnNi high entropy alloy were deformed at varying strain rates ranging from 1 × 103 to 3 × 103 s-1 using a split-Hopkinson pressure bar (SHPB) system. The dynamic yield strength of the CoCrFeMnNi high entropy alloy increases with increasing strain rate. The Zerilli-Armstrong (Z-A) plastic model was applied to model the dynamic flow behavior of the CoCrFeMnNi high entropy alloy, and the constitutive relationship was obtained. Serration behavior during plastic deformation was observed in the stress-strain curves. The mechanism for serration behavior of the alloy deformed at high strain rate is proposed.

  14. Compressive properties of commercially available polyurethane foams as mechanical models for osteoporotic human cancellous bone

    PubMed Central

    Patel, Purvi SD; Shepherd, Duncan ET; Hukins, David WL

    2008-01-01

    Background Polyurethane (PU) foam is widely used as a model for cancellous bone. The higher density foams are used as standard biomechanical test materials, but none of the low density PU foams are universally accepted as models for osteoporotic (OP) bone. The aim of this study was to determine whether low density PU foam might be suitable for mimicking human OP cancellous bone. Methods Quasi-static compression tests were performed on PU foam cylinders of different lengths (3.9 and 7.7 mm) and of different densities (0.09, 0.16 and 0.32 g.cm-3), to determine the Young's modulus, yield strength and energy absorbed to yield. Results Young's modulus values were 0.08–0.93 MPa for the 0.09 g.cm-3 foam and from 15.1–151.4 MPa for the 0.16 and 0.32 g.cm-3 foam. Yield strength values were 0.01–0.07 MPa for the 0.09 g.cm-3 foam and from 0.9–4.5 MPa for the 0.16 and 0.32 g.cm-3 foam. The energy absorbed to yield was found to be negligible for all foam cylinders. Conclusion Based on these results, it is concluded that 0.16 g.cm-3 PU foam may prove to be suitable as an OP cancellous bone model when fracture stress, but not energy dissipation, is of concern. PMID:18844988

  15. Chest tube insertion - series (image)

    MedlinePlus

    ... cause the lung to collapse, such as: air leaks from the lung into the chest (pneumothorax) bleeding ... nursing staff will carefully check for possible air leaks, breathing difficulties, and need for additional oxygen. Frequent ...

  16. Chest drainage systems in use.

    PubMed

    Zisis, Charalambos; Tsirgogianni, Katerina; Lazaridis, George; Lampaki, Sofia; Baka, Sofia; Mpoukovinas, Ioannis; Karavasilis, Vasilis; Kioumis, Ioannis; Pitsiou, Georgia; Katsikogiannis, Nikolaos; Tsakiridis, Kosmas; Rapti, Aggeliki; Trakada, Georgia; Karapantzos, Ilias; Karapantzou, Chrysanthi; Zissimopoulos, Athanasios; Zarogoulidis, Konstantinos; Zarogoulidis, Paul

    2015-03-01

    A chest tube is a flexible plastic tube that is inserted through the chest wall and into the pleural space or mediastinum. It is used to remove air in the case of pneumothorax or fluid such as in the case of pleural effusion, blood, chyle, or pus when empyema occurs from the intrathoracic space. It is also known as a Bülau drain or an intercostal catheter. Insertion of chest tubes is widely performed by radiologists, pulmonary physicians and thoracic surgeons. Large catheters or small catheters are used based on each situation that the medical doctor encounters. In the current review we will focus on the chest drain systems that are in use. PMID:25815304

  17. Managing acute enigmatic chest pain.

    PubMed

    Wielgosz, A T

    1996-09-01

    The author comments on the report by Dr. Akbar Panju and associates (see pages 541 to 547 of this issue) on patient outcomes associated with a discharge diagnosis of "chest pain not yet diagnosed." Acute chest pain without evidence of cardiac involvement presents a diagnostic challenge for the clinician, particularly in the present climate of cost containment. Esophageal disorders and psychiatric conditions appear to be the most prevalent causes of noncardiac chest pain. Although screening by means of electrocardiography and cardiac enzyme testing may rule out acute ischemia, and other tests may clearly point to a gastrointestinal cause, it is possible for cardiac and gastrointestinal problems to present simultaneously. Understanding and managing persistent chest pain even after a diagnosis has been made continues to challenge clinicians and researchers, and further progress in this area will depend on multidisciplinary collaboration.

  18. Managing acute enigmatic chest pain.

    PubMed Central

    Wielgosz, A T

    1996-01-01

    The author comments on the report by Dr. Akbar Panju and associates (see pages 541 to 547 of this issue) on patient outcomes associated with a discharge diagnosis of "chest pain not yet diagnosed." Acute chest pain without evidence of cardiac involvement presents a diagnostic challenge for the clinician, particularly in the present climate of cost containment. Esophageal disorders and psychiatric conditions appear to be the most prevalent causes of noncardiac chest pain. Although screening by means of electrocardiography and cardiac enzyme testing may rule out acute ischemia, and other tests may clearly point to a gastrointestinal cause, it is possible for cardiac and gastrointestinal problems to present simultaneously. Understanding and managing persistent chest pain even after a diagnosis has been made continues to challenge clinicians and researchers, and further progress in this area will depend on multidisciplinary collaboration. PMID:8804262

  19. Compression Mechanism of Goethite: a Possibility of H-bond Symmetrization under Pressure

    NASA Astrophysics Data System (ADS)

    Nagai, T.; Kagi, H.; Yamanaka, T.

    2002-05-01

    The structure of goethite (α -FeOOH) can be described in terms of a slightly distorted hexagonally close packed oxygen arrangement with Fe atoms occupying two-thirds of octahedral sites. The nonlinear H-bonding in goethite is known to be of moderate strength. Since we have studied weak H-bonding in brucite-related minerals at high pressure (Parise et al., 1999, Nagai et al., 2000), it is of great interest to compare how moderate H-bonding behaves at high pressure. In this study, we performed in-situ synchrotron X-ray powder experiments up to 25 GPa at BL-18C in the Photon Factory, Japan. The diffraction data obtained at several pressure points below 11GPa were successfully analyzed using the Rietveld structural refinement method. All diffraction patterns obtained up to 25 GPa were assigned as goethite. Compression behavior of goethite is anisotropic and the a-axis is almost two times softer than the b- and c-axes. The second order Birch-Murnaghan EOS fitting to P-V data yields a bulk modulus K0=111(2) GPa with K-f=4. We could not refine the H atom positions, because their scattering power is negligible for X-ray. Nevertheless, the refinement of Fe, hydroxy-O and oxy-O positions enables us to discuss the variation of bond length as a function of pressure. For example, the H bonded O...O distance shortens with increasing pressure at the rate of about 0.024Å/GPa and is 2.577Å at 9 GPa. Although the pressure dependency is smaller than that of brucite (about 0.04Å/GPa from Nagai et al., 2000), it is interesting that the extrapolation of the H bonded O...O distance is expected to be less than 2.5Å above 13 GPa, at which William and Guenther (1996) reported that the hydroxyl bending vibrations of goethite converge in frequency. Since some studies for the ice VIII-X transition have suggested that proton tunneling is enhanced when the H-bonded O...O distance shortens to less than 2. 5Å, we can expect H-bond symmetrization to occur at higher pressure.

  20. Calibration of the mechanical properties in a finite element model of a lumbar vertebra under dynamic compression up to failure.

    PubMed

    Garo, Anaïs; Arnoux, Pierre Jean; Wagnac, Eric; Aubin, Carl Eric

    2011-12-01

    Finite element models (FEM) dedicated to vertebral fracture simulations rarely take into account the rate dependency of the bone material properties due to limited available data. This study aims to calibrate the mechanical properties of a vertebral body FEM using an inverse method based on experiments performed at slow and fast dynamic loading conditions. A detailed FEM of a human lumbar vertebral body (23,394 elements) was developed and tested under compression at 2,500 and 10 mm s⁻¹. A central composite design was used to adjust the mechanical properties (Young modulus, yield stress, and yield strain) while optimizing four criteria (ultimate strain and stress of cortical and trabecular bone) until the failure load and energy at failure reached experimental results from the literature. At 2,500 mm s⁻¹, results from the calibrated simulation were in good agreement with the average experimental data (1.5% difference for the failure load and 0.1% for the energy). At 10 mm s⁻¹, they were in good agreement with the average experimental failure load (0.6% difference), and within one standard deviation of the reported range of energy to failure. The proposed method provides a relevant mean to identify the mechanical properties of the vertebral body in dynamic loadings.

  1. Quasi-static Tensile and Compressive Behavior of Nanocrystalline Tantalum Based on Miniature Specimen Testing—Part II: Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Ligda, J.; D'Antuono, D. Scotto; Taheri, M. L.; Schuster, B. E.; Wei, Q.

    2016-09-01

    In Part I of this work (this issue), we presented the microstructure of tantalum processed by high-pressure torsion (HPT). In this part, we will present results based on site-specific micro-mechanical testing. The experimental techniques were used due to the intrinsic microstructure gradient associated with HPT processing. The primary objective is to explore the grain size effect on the quasi-static mechanical properties of HPT processed tantalum with ultrafine grained (UFG, grain size d < 1000 nm and d > 100 nm) and nanocrystalline (NC, d < 100 nm) microstructure. Two distinct deformation modes are observed, i.e. a homogeneous (non-shearing) region and a localized (shear banding) region. Transmission electron microscopy (TEM) and orientation imaging microscopy (OIM) show that the shear bands form by grain rotation. Comparing d in these two regions to the mechanism proposed in the literature shows that reduced d in the shear banding region is more susceptible to localized shearing via grain rotation. This work unifies, or at least further substantiates, the notion that body-centered cubic metals with UFG/NC microstructure tend to have localized shear band even under quasi-static uniaxial compression.

  2. Fabrication and mechanical properties of PLLA/PCL/HA composites via a biomimetic, dip coating, and hot compression procedure.

    PubMed

    Charles, L F; Shaw, M T; Olson, J R; Wei, M

    2010-06-01

    Currently, the bone-repair biomaterials market is dominated by high modulus metals and their alloys. The problem of stress-shielding, which results from elastic modulus mismatch between these metallic materials and natural bone, has stimulated increasing research into the development of polymer-ceramic composite materials that can more closely match the modulus of bone. In this study, we prepared poly(L: -lactic acid)/hydroxyapatite/poly(epsilon-caprolactone) (PLLA/HA/PCL) composites via a four-step process, which includes surface etching of the fiber, the deposition of the HA coating onto the PLLA fibers through immersion in simulated body fluid (SBF), PCL coating through a dip-coating process, and hot compression molding. The initial HA-coated PLLA fiber had a homogeneous and continuous coating with a gradient structure. The effects of HA: PCL ratio and molding temperature on flexural mechanical properties were studied and both were shown to be important to mechanical properties. Mechanical results showed that at low molding temperatures and up to an HA: PCL volume ratio of 1, the flexural strain decreased while the flexural modulus and strength increased. At higher mold temperatures with a lower viscosity of the PCL a HA: PCL ratio of 1.6 gave similar properties. The process successfully produced composites with flexural moduli near the lower range of bone. Such composites may have clinical use for load bearing bone fixation.

  3. Transfer of highly porous nanoparticle layers to various substrates through mechanical compression.

    PubMed

    Schopf, Sven O; Salameh, Samir; Mädler, Lutz

    2013-05-01

    A new two-step layer transfer process is introduced that is capable of fabricating mechanically stabilized highly porous nanoparticle layers on various substrates. In a first step titanium dioxide nanoparticles were synthesized with Flame-Spray-Pyrolysis and accumulated on a filter paper in the gas phase. In a second step this highly porous filter cake is subsequently transferred to a final substrate via low pressure lamination at room temperature. This leads to mechanical restructuring and stabilization of the porous layer. Pore size analysis indicates homogenization of the layers through rearrangement of the aggregates inside the layers that increases with applied pressure. Additionally, the Young's moduli of the layers were quantified through Colloidal-Probe-Technique indentation measurements with an Atomic-Force-Microscope. The highest lamination pressure of 2.5 MPa resulted in triplication of the Young's modulus. The results show that our novel two-step layer transfer process leads to mechanically stabilized layers that preserve their high porosity. Through the decoupling of the high temperature nanoparticle synthesis and the final substrate the process also enables the possibility to apply temperature sensitive substrates such as polypropylene foil. PMID:23532446

  4. ENDOCHONDRAL GROWTH IN GROWTH PLATES OF THREE SPECIES AT TWO ANATOMICAL LOCATIONS MODULATED BY MECHANICAL COMPRESSION AND TENSION

    PubMed Central

    Stokes, Ian A.F.; Aronsson, David D.; Dimock, Abigail N.; Cortright, Valerie; Beck., Samantha

    2006-01-01

    SUMMARY Purpose Sustained mechanical loading alters longitudinal growth of bones, and this growth sensitivity to load has been implicated in progression of skeletal deformities during growth. The objective of this study was to quantify the relationship between altered growth and different magnitudes of sustained altered stress in a diverse set of non-human growth plates. Methods The sensitivity of endochondral growth to differing magnitudes of sustained compression or distraction stress was measured in growth plates of three species of immature animals (rats, rabbits, calves) at two anatomical locations (caudal vertebra and proximal tibia) with two different ages of rats and rabbits. An external loading apparatus was applied for eight days and growth was measured as the distance between fluorescent markers administered 24 and 48 hours prior to euthanasia. Results An apparently linear relationship between stress and percentage growth modulation (percent difference between loaded and control growth plates) was found, with distraction accelerating growth and compression slowing growth. The growth-rate sensitivity to stress was between 9.2 and 23.9% per 0.1 MPa for different growth plates, and averaged 17.1% per 0.1 MPa. The growth-rate sensitivity to stress differed between vertebrae and the proximal tibia (15 and 18.6 percent per 0.1 MPa respectively). The range of control growth rates of different growth plates was large (30 microns/day for rat vertebrae to 366 microns/day for rabbit proximal tibia). Conclusions The relatively small differences in growth-rate sensitivity to stress for a diverse set of growth plates suggests that these results might be generalized to other growth plates, including human. These data may be applicable to planning the management of progressive deformities in patients having residual growth. PMID:16705695

  5. Mechanical properties of alumina-PEEK unidirectional composite - Compression, shear, and tension

    NASA Technical Reports Server (NTRS)

    Kriz, R. D.; Mccolskey, J. D.

    1990-01-01

    An Al2O3 (alumina)-fiber composite with high strain to failure was fabricated with a thermal plastic PEEK (poly-ether-ether-ketone). The Al2O3-PEEK composite shows a marked improvement over thermally setting composite in that it absorbs 150 percent more elastic-strain energy at 76 K than at room temperature. This increase in fracture toughness at low temperatures can provide improved fatigue performance for thermal isolation straps at low temperature. Other mechanical property results suggest improvements for applications where graphite-epoxy materials are presently being used at low temperatures and where light weight is not a critical issue.

  6. Mechanics of Boundary Layer Transition. Part 5: Boundary Layer Stability theory in incompressible and compressible flow

    NASA Technical Reports Server (NTRS)

    Mack, L. M.

    1967-01-01

    The fundamentals of stability theory, its chief results, and the physical mechanisms at work are presented. The stability theory of the laminar boundary determines whether a small disturbance introduced into the boundary layer will amplify or damp. If the disturbance damps, the boundary layer remains laminar. If the disturbance amplifies, and by a sufficient amount, then transition to turbulence eventually takes place. The stability theory establishes those states of the boundary layer which are most likely to lead to transition, identifys those frequencies which are the most dangerous, and indicates how the external parameters can best be changed to avoid transition.

  7. Compression Ratio Adjuster

    NASA Technical Reports Server (NTRS)

    Akkerman, J. W.

    1982-01-01

    New mechanism alters compression ratio of internal-combustion engine according to load so that engine operates at top fuel efficiency. Ordinary gasoline, diesel and gas engines with their fixed compression ratios are inefficient at partial load and at low-speed full load. Mechanism ensures engines operate as efficiently under these conditions as they do at highload and high speed.

  8. Mechanisms of fracture of the free surface of shock-compressed metals

    SciTech Connect

    Mokhova, V. V. Mikhailov, A. L.; Til’kunov, A. V.; Orlov, N. I.; Kanunova, L. I.; Bragunets, V. A.; Tkachenko, M. I.; Simakov, V. G.; Sokolov, S. S.; Podurets, A. M.

    2015-12-15

    The mechanisms of the ejection of aluminum and copper microparticles from the free surfaces of these metals have been studied under conditions of the escape of a moderate-intensity shock wave from a sample. The free surfaces of samples contained 0.7–0.9 mm deep artificial wells and protrusions simulating (on a greater scale of 10: 1) the natural surface roughness retained upon mechanical processing. The pressure in a shock-wave pulse at the base of a protrusion was controlled within P = 5–20 GPa (i.e., below the melting region), and the variable duration of pressure pulses was 0.02, 0.2, and 1 μs. Analysis of the free surfaces of postloaded samples showed that, for certain loading and roughness parameters, the ejection of metal from vertices of protruding ridges or pyramids (as a result of the longitudinal fracture) was about ten times greater than the amount of metal ejected in the form of cumulative jets from wells. The amount of ejected metal and the size distribution of metal microparticles were quantitatively characterized using “soft collecting targets” and by measuring mass losses of samples upon fracture.

  9. On the mechanical behavior of WS2 nanotubes under axial tension and compression

    PubMed Central

    Kaplan-Ashiri, Ifat; Cohen, Sidney R.; Gartsman, Konstantin; Ivanovskaya, Viktoria; Heine, Thomas; Seifert, Gotthard; Wiesel, Inna; Wagner, H. Daniel; Tenne, Reshef

    2006-01-01

    The mechanical properties of materials and particularly the strength are greatly affected by the presence of defects; therefore, the theoretical strength (≈10% of the Young's modulus) is not generally achievable for macroscopic objects. On the contrary, nanotubes, which are almost defect-free, should achieve the theoretical strength that would be reflected in superior mechanical properties. In this study, both tensile tests and buckling experiments of individual WS2 nanotubes were carried out in a high-resolution scanning electron microscope. Tensile tests of MoS2 nanotubes were simulated by means of a density-functional tight-binding-based molecular dynamics scheme as well. The combination of these studies provides a microscopic picture of the nature of the fracture process, giving insight to the strength and flexibility of the WS2 nanotubes (tensile strength of ≈16 GPa). Fracture analysis with recently proposed models indicates that the strength of such nanotubes is governed by a small number of defects. A fraction of the nanotubes attained the theoretical strength indicating absence of defects. PMID:16407141

  10. Tissue engineering of cartilage using a mechanobioreactor exerting simultaneous mechanical shear and compression to simulate the rolling action of articular joints.

    PubMed

    Shahin, Kifah; Doran, Pauline M

    2012-04-01

    The effect of dynamic mechanical shear and compression on the synthesis of human tissue-engineered cartilage was investigated using a mechanobioreactor capable of simulating the rolling action of articular joints in a mixed fluid environment. Human chondrocytes seeded into polyglycolic acid (PGA) mesh or PGA-alginate scaffolds were precultured in shaking T-flasks or recirculation perfusion bioreactors for 2.5 or 4 weeks prior to mechanical stimulation in the mechanobioreactor. Constructs were subjected to intermittent unconfined shear and compressive loading at a frequency of 0.05 Hz using a peak-to-peak compressive strain amplitude of 2.2% superimposed on a static axial compressive strain of 6.5%. The mechanical treatment was carried out for up to 2.5 weeks using a loading regime of 10 min duration each day with the direction of the shear forces reversed after 5 min and release of all loading at the end of the daily treatment period. Compared with shaking T-flasks and mechanobioreactor control cultures without loading, mechanical treatment improved the amount and quality of cartilage produced. On a per cell basis, synthesis of both major structural components of cartilage, glycosaminoglycan (GAG) and collagen type II, was enhanced substantially by up to 5.3- and 10-fold, respectively, depending on the scaffold type and seeding cell density. Levels of collagen type II as a percentage of total collagen were also increased after mechanical treatment by up to 3.4-fold in PGA constructs. Mechanical treatment had a less pronounced effect on the composition of constructs precultured in perfusion bioreactors compared with perfusion culture controls. This work demonstrates that the quality of tissue-engineered cartilage can be enhanced significantly by application of simultaneous dynamic mechanical shear and compression, with the greatest benefits evident for synthesis of collagen type II.

  11. The Impact of Posture on the Mechanical Properties of a Functional Spinal Unit During Cyclic Compressive Loading.

    PubMed

    Barrett, Jeff M; Gooyers, Chad E; Karakolis, Thomas; Callaghan, Jack P

    2016-08-01

    To assess how posture affects the transmission of mechanical energy up the spinal column during vibration, 18 porcine functional spinal units (FSUs) were exposed to a sinusoidal force (1500 ± 1200 N) at 5 Hz for 120 min in either a flexed, extended, or neutral posture. Force and FSU height were measured continuously throughout the collection. From these data, specimen height loss, dynamic stiffness, hysteresis, and parameters from a standard linear solid (SLS) model were determined and analyzed for differences between postures. Posture had an influence on all of these parameters. In extension, the FSU had higher dynamic stiffness values than when neutral or flexed (p < 0.0001). In flexion, the FSU had higher hysteresis than both an extended or neutral posture (p < 0.0001). Height loss was greatest in a flexed posture and smallest in an extended posture (p < 0.0001). In extension, the series spring element in the SLS model had a stiffness value higher than both flexed and neutral posture conditions, whereas the stiffness in the parallel spring was the same between extension and neutral (p < 0.01), both higher than in flexion. Viscosity coefficients were highest in extension compared to both flexed and neutral (p < 0.01). Based on these results, it was determined that posture had a significant influence in determining the mechanical properties of the spine when exposed to cyclic compressive loading. PMID:27322199

  12. Mechanisms of strong pressure wave generations during knocking combustion: compressible reactive flow simulations with detailed chemical kinetics

    NASA Astrophysics Data System (ADS)

    Terashima, Hiroshi; Koshi, Mitsuo

    2014-11-01

    Knocking is a very severe pressure oscillation caused by interactions between flame propagation and end-gas autoignition in spark-assisted engines. In this study, knocking combustion modeled in one-dimensional space is simulated using a highly efficient compressible flow solver with detailed chemical kinetics for clarifying the process of knocking occurrence. Especially, mechanisms of strong pressure wave generation are addressed. A robust and fast explicit integration method is used to efficiently handle stiff chemistry, and species bundling for effectively estimating the diffusion coefficients. The detailed mechanisms such as n-butane of 113 species and n-heptane of 373 species are directly applied. Results demonstrate that the negative temperature coefficient (NTC) region of n-heptane significantly influence the knocking timing and intensity. In the NTC region, stronger pressure wave is generated due to rapid heat release of a very small portion in the end-gas, which is attributed to low temperature oxidation and inhomogeneous temperature distributions in the end-gas. The knocking intensity is thus amplified in the NTC region, taking a maximum value. In the case of n-butane with no NTC region, relatively weak knocking intensity is observed in all conditions with no clear peak.

  13. Mechanisms of flow through compressible porous beds in sedimentation, filtration, centrifugation, deliquoring, and ceramic processing

    SciTech Connect

    Tiller, F.M.

    1992-06-01

    The University of Houston research program is aimed at the specific area of solid/liquid separation including sedimentation, thickening, cake filtration, centrifugation, expression, washing, deep-bed filtration, screening, and membrane separation. Unification of the theoretical approaches to the various solid/liquid separation operations is the principle objective of the research. Exploring new aspects of basic separation mechanisms, verification of theory with experiment, development of laboratory procedures for obtaining data for design, optimizing operational methods, and transferring the results to industry are a part of the Houston program. New methodology developed in our program now permits an engineer or scientist to handle thickening, cake filtration, centrigual filtration, and expression in a unified manner. The same fundamental equations are simply adapted to the differing parameters and conditions related to the various modes of separation. As the system is flexible and adaptable to computational software, new developments can continually be added. Discussions of the various research projects in this report have been kept to a minimum and are principally qualitative. The length of the report would be excessive if each topic were covered in depth. Although the number of research topics may appear larger than one would expect, many are closely interconnected and reflect our philosophy of working in apparently diverse fields such as ceramics, mining, wastewater, food, chemical processing, and oil well operations.

  14. Buckling and mechanical instability of ZnO nanorods grown on different substrates under uniaxial compression.

    PubMed

    Riaz, M; Fulati, A; Zhao, Q X; Nur, O; Willander, M; Klason, P

    2008-10-15

    Mechanical instability and buckling characterization of vertically aligned single-crystal ZnO nanorods grown on different substrates including Si, SiC and sapphire (α-Al(2)O(3)) was done quantitatively by the nanoindentation technique. The nanorods were grown on these substrates by the vapor-liquid-solid (VLS) method. The critical load for the ZnO nanorods grown on the Si, SiC and Al(2)O(3) substrates was found to be 188, 205 and 130 µN, respectively. These observed critical loads were for nanorods with 280 nm diameters and 900 nm length using Si as a substrate, while the corresponding values were 330 nm, 3300 nm, and 780 nm, 3000 nm in the case of SiC and Al(2)O(3) substrates, respectively. The corresponding buckling energies calculated from the force displacement curves were 8.46 × 10(-12), 1.158 × 10(-11) and 1.092 × 10(-11) J, respectively. Based on the Euler model for long nanorods and the J B Johnson model (which is an extension of the Euler model) for intermediate nanorods, the modulus of elasticity of a single rod was calculated for each sample. Finally, the critical buckling stress and strain were also calculated for all samples. We found that the buckling characteristic is strongly dependent on the quality, lattice mismatch and adhesion of the nanorods with the substrate. PMID:21832659

  15. Postoperative Complications Leading to Death after Coagulum Pyelolithotomy in a Tetraplegic Patient: Can We Prevent Prolonged Ileus, Recurrent Intestinal Obstruction due to Adhesions Requiring Laparotomies, Chest Infection Warranting Tracheostomy, and Mechanical Ventilation?

    PubMed

    Vaidyanathan, Subramanian; Soni, Bakul; Singh, Gurpreet; Hughes, Peter

    2013-01-01

    A 22-year-old male sustained C-6 tetraplegia in 1992. In 1993, intravenous pyelography revealed normal kidneys. Suprapubic cystostomy was performed. He underwent open cystolithotomy in 2004 and 2008. In 2009, computed tomography revealed bilateral renal calculi. Coagulum pyelolithotomy of left kidney was performed. Pleura and peritoneum were opened. Peritoneum could not be closed. Following surgery, he developed pulmonary atelectasis; he required tracheostomy and mechanical ventilation. He did not tolerate nasogastric feeding. CT of abdomen revealed bilateral renal calculi and features of proximal small bowel obstruction. Laparotomy revealed small bowel obstruction due to dense inflammatory adhesions involving multiple small bowel loops which protruded through the defect in sigmoid mesocolon and fixed posteriorly over the area of previous intervention. All adhesions were divided. The wide defect in mesocolon was not closed. In 2010, this patient again developed vomiting and distension of abdomen. Laparotomy revealed multiple adhesions. He developed chest infection and required ventilatory support again. He developed pressure sores and depression. Later abdominal symptoms recurred. This patient's general condition deteriorated and he expired in 2011. Conclusion. Risk of postoperative complications could have been reduced if minimally invasive surgery had been performed instead of open surgery to remove stones from left kidney. Suprapubic cystostomy predisposed to repeated occurrence of stones in urinary bladder and kidneys. Spinal cord physicians should try to establish intermittent catheterisation regime in tetraplegic patients. PMID:23533931

  16. Micromechanical finite-element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone-hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering.

    PubMed

    Eshraghi, Shaun; Das, Suman

    2012-08-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite-element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30 vol.% HA. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30, respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical FEA model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any HA loading to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. The results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient- and site-specific composite tissue-engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing.

  17. [Chest ultrasonography in pleurapulmonary disease].

    PubMed

    Gallego Gómez, M P; García Benedito, P; Pereira Boo, D; Sánchez Pérez, M

    2014-01-01

    Although the initial diagnosis and follow-up of pleuropulmonary disease are normally done with plain chest films and the gold standard for chest disease is computed tomography, diverse studies have established the usefulness of chest ultrasonography in the diagnosis of different pleuropulmonary diseases like pleural effusion and lung consolidation, among others. In this article, we show the different ultrasonographic patterns for pleuropulmonary disease. The availability of ultrasonography in different areas (ICU, recovery areas) makes this technique especially important for critical patients because it obviates the need to transfer the patient. Moreover, ultrasonography is noninvasive and easy to repeat. On the other hand, it enables the direct visualization of pleuropulmonary disease that is necessary for interventional procedures. PMID:22819690

  18. [Chest ultrasonography in pleurapulmonary disease].

    PubMed

    Gallego Gómez, M P; García Benedito, P; Pereira Boo, D; Sánchez Pérez, M

    2014-01-01

    Although the initial diagnosis and follow-up of pleuropulmonary disease are normally done with plain chest films and the gold standard for chest disease is computed tomography, diverse studies have established the usefulness of chest ultrasonography in the diagnosis of different pleuropulmonary diseases like pleural effusion and lung consolidation, among others. In this article, we show the different ultrasonographic patterns for pleuropulmonary disease. The availability of ultrasonography in different areas (ICU, recovery areas) makes this technique especially important for critical patients because it obviates the need to transfer the patient. Moreover, ultrasonography is noninvasive and easy to repeat. On the other hand, it enables the direct visualization of pleuropulmonary disease that is necessary for interventional procedures.

  19. Continuous chest compression pediatric cardiopulmonary resuscitation after witnessed electrocution.

    PubMed

    Chalkias, Athanasios; Iacovidou, Nicoletta; Xanthos, Theodoros

    2014-06-01

    Electrical injury is a relatively infrequent but potentially devastating multisystem injury with high morbidity and mortality. We describe the case of an 11-year-old boy who suffered loss of his consciousness after touching an electrical cable.

  20. High frequency chest compression effects on cardio-respiratory interaction.

    PubMed

    Lee, Jongwon; Lee, Yong Wan; Warwick, Warren J

    2008-01-01

    In this study, we present a quantitative approach to the analysis of the HFCC effect on heart rate changes in the respiratory stage according to different pulsation conditions with HFCC pulsation and without HFCC pulsation. We have shown that the heart rate increases with higher pressure settings revealing different patterns depending on the respiration stages. For our interaction study of how the heart and lungs were affected by HFCC, phase synchronization was considered and compared under different conditions which determine the real biological phenomenon for nonlinear or linear oscillatory coupling. The subject for this study was young and healthy, so these preliminary results should be verified with more detailed studies from abundant subjects to increase HFCC efficacy for lung disease patients. Interestingly, the indication or tracking of heart rate changes, respiration rate changes, or synchronization epoch can be the standard index for how much the cardiac and respiratory system improve using HFCC during therapy time or after therapy time.

  1. Contemporary management of flail chest.

    PubMed

    Vana, P Geoff; Neubauer, Daniel C; Luchette, Fred A

    2014-06-01

    Thoracic injury is currently the second leading cause of trauma-related death and rib fractures are the most common of these injuries. Flail chest, as defined by fracture of three or more ribs in two or more places, continues to be a clinically challenging problem. The underlying pulmonary contusion with subsequent inflammatory reaction and right-to-left shunting leading to hypoxia continues to result in high mortality for these patients. Surgical stabilization of the fractured ribs remains controversial. We review the history of management for flail chest alone and when combined with pulmonary contusion. Finally, we propose an algorithm for nonoperative and surgical management.

  2. Coded aperture compressive temporal imaging.

    PubMed

    Llull, Patrick; Liao, Xuejun; Yuan, Xin; Yang, Jianbo; Kittle, David; Carin, Lawrence; Sapiro, Guillermo; Brady, David J

    2013-05-01

    We use mechanical translation of a coded aperture for code division multiple access compression of video. We discuss the compressed video's temporal resolution and present experimental results for reconstructions of > 10 frames of temporal data per coded snapshot.

  3. Acute Myocardial Infarction Following Blunt Chest Trauma and Coronary Artery Dissection.

    PubMed

    Abdolrahimi, Safar Ali; Sanati, Hamid Reza; Ansari-Ramandi, Mohammad Mostafa; Heris, Saeed Oni; Maadani, Mohsen

    2016-06-01

    Blunt chest traumatic coronary artery dissection is an uncommon cause of atherosclerotic and non-atherosclerotic Acute Myocardial Infarction (AMI). Injuries of the coronary artery after blunt chest trauma are caused by different mechanisms such as vascular spasm, dissection and intimal tear or rupture of an existing thrombus formation. Chest pain might be masked by other injuries in patients with multiple traumas in car accident. Present case report is on a 37-year-old male without any specific past medical history who reported to the emergency department of a hospital with chest discomfort and was discharged with the impression of chest wall pain. After three days he experienced severe chest pain and he was admitted with the impression of acute coronary syndrome and underwent coronary angiography which showed Left Anterior Descending (LAD) artery dissection. The possibility of injury of the coronary artery should be kept in mind after blunt trauma to the chest. This condition is sometimes underdiagnosed. Its diagnosis may be difficult because chest pain can be interpreted as being secondary to chest wall contusion or it may be overshadowed by other injuries. Coronary dissection diagnosis after chest trauma requires clinical suspicion and systematic evaluation. Electrocardiography (ECG) should be done for every patient with thoracic trauma as the clinical findings may be misleading. PMID:27504338

  4. Compression asphyxia from a human pyramid.

    PubMed

    Tumram, Nilesh Keshav; Ambade, Vipul Namdeorao; Biyabani, Naushad

    2015-12-01

    In compression asphyxia, respiration is stopped by external forces on the body. It is usually due to an external force compressing the trunk such as a heavy weight on the chest or abdomen and is associated with internal injuries. In present case, the victim was trapped and crushed under the falling persons from a human pyramid formation for a "Dahi Handi" festival. There was neither any severe blunt force injury nor any significant pathological natural disease contributing to the cause of death. The victim was unable to remove himself from the situation because his cognitive responses and coordination were impaired due to alcohol intake. The victim died from asphyxia due to compression of his chest and abdomen. Compression asphyxia resulting from the collapse of a human pyramid and the dynamics of its impact force in these circumstances is very rare and is not reported previously to the best of our knowledge.

  5. Monsters do exist: an unusual case of chest pain.

    PubMed

    Thomas, Mari Lluon

    2014-01-21

    A 19-year-old man presented to the emergency department with a 3-week history of chest pain. Despite normal examination, bloods and observations of his chest X-ray revealed a large opacity in the middle and lower right zone. Further imaging revealed a multicystic mediastinal teratoma. He was admitted under the respiratory physicians who arranged further investigations and discussed his case with the lung and testicular multidisciplinary team. He was started on neoadjuvant chemotherapy with a plan for future definitive surgical resection. Four months later he suddenly deteriorated due to airway compression from the tumour. He underwent an emergency thoracotomy and tumour resection. He is currently doing well and is thought to have a good prognosis following complete resection of his tumour. This case report summarises this rare diagnosis and emphasises the need for careful evaluation of patients despite their initial well appearance, especially in patients who are reattending.

  6. Actinomycosis involving the chest wall: CT findings

    SciTech Connect

    Webb, W.R.; Sagel, S.S.

    1982-11-01

    Two cases of pulmonary actinomycosis with extension to involve the chest wall that were evaluated using computerized tomography are reported. In both cases, the relation of pulmonary and chest wall disease was best shown using CT. (KRM)

  7. Control of shock unsteadiness in shock boundary-layer interaction on a compression corner using mechanical vortex generators

    NASA Astrophysics Data System (ADS)

    Verma, S. B.; Manisankar, C.; Raju, C.

    2012-07-01

    An experimental study was conducted to control the unsteadiness of separation shock in a Mach 2 24° compression ramp-induced interaction using mechanical vortex generators (VG). Control devices in the form of an array of single-row delta-ramps were placed upstream of the interaction region and tested for two streamwise locations with respect to the boundary layer thickness ( δ) at the interaction location and height ` h' of the delta-ramps, i.e., at 27.5 δ or h/ δ = 0.65 and at 12.5 δ or h/ δ = 0.26, respectively. Surface oil study revealed traces of streamwise counter-rotating vortex pairs generated downstream of these devices. Measurements using pressure-sensitive paint also showed a spanwise sinusoidal pattern of wall pressure variation indicating generation of streamwise vortices from these control devices. These vortices, on interaction with the reverse flow in the separation bubble, replaced a well-defined separation line (for no control) by a highly corrugated separation line. In the region of separation, the mean pressure distribution gets modified while the peak rms value in the intermittent region of separation showed significant changes. Additionally, the spanwise spacing ` s' of the vertex of the delta ramps seemed to be an important parameter in controlling the peak rms value. A decrease in this spacing, i.e., VG1 with s = 0, significantly reduced the peak rms value (by 50 and 35 %) while an increase in the spacing, i.e., VG2 with s = 1 mm, consistently showed an increase (by 12 and 30 %) in the separation shock unsteadiness relative to no control, irrespective of their placement location (of h/ δ = 0.65 and 0.26, respectively).

  8. Mechanical Testing of PMCs under Simulated Rapid Heat-Up Propulsion Environments. II; In-Plane Compressive Behavior

    NASA Technical Reports Server (NTRS)

    Stokes, Eric H.; Shin, E. Eugene; Sutter, James K.

    2003-01-01

    .e., plastization of polymeric material by water, the internal pressure generated by the volatilization of water at elevated temperatures, and hydrolytic chemical decomposition. However, moisture is lost from the material at increasing rates as temperature increases. Second, because PMCs are good thermal insulators, when they are externally heated at even mild rates large thermal gradients can develop within the material. At temperatures where a material property changes rapidly with temperature the presence of a large thermal gradient is unacceptable for intrinsic property characterization purposes. Therefore, long hold times are required to establish isothermal conditions. However, in the service environments high-heating-rates, high temperatures, high-loading rates are simultaneous present along with residual moisture. In order to capture the effects of moisture on the material, holding at- temperature until isothermal conditions are reached is unacceptable particularly in materials with small physical dimensions. Thus, the effects due to moisture on the composite's mechanical characteristics, ie., their so-called analog response, may be instructive. One approach employed in this program was rapid heat-up (approx. 200 F/sec.) and loading of both dry and wet in-plane compressive specimens to examine the effects of moisture on this resin dominated mechanical property of the material.

  9. DNABIT Compress - Genome compression algorithm.

    PubMed

    Rajarajeswari, Pothuraju; Apparao, Allam

    2011-01-01

    Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, "DNABIT Compress" for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our proposed algorithm achieves the best compression ratio for DNA sequences for larger genome. Significantly better compression results show that "DNABIT Compress" algorithm is the best among the remaining compression algorithms. While achieving the best compression ratios for DNA sequences (Genomes),our new DNABIT Compress algorithm significantly improves the running time of all previous DNA compression programs. Assigning binary bits (Unique BIT CODE) for (Exact Repeats, Reverse Repeats) fragments of DNA sequence is also a unique concept introduced in this algorithm for the first time in DNA compression. This proposed new algorithm could achieve the best compression ratio as much as 1.58 bits/bases where the existing best methods could not achieve a ratio less than 1.72 bits/bases.

  10. Radiology of occupational chest disease

    SciTech Connect

    Solomon, A. ); Kreel, L.

    1989-01-01

    Radiologic manifestations of occupational lung disease are summarized and classified in this book according to the ILO system. The interpretation of chest roentgenograms outlines the progression of each disease and is accompanied with clinically-oriented explanations. Some of the specific diseases covered include asbestosis, coal worker's pneumoconiosis, silicosis, non-mining inhalation of silica and silicates, beryllium induced disease, inhalation of organics and metallics, and occupationally induced asthma.

  11. Pleural controversy: optimal chest tube size for drainage.

    PubMed

    Light, Richard W

    2011-02-01

    In recent years, a higher and higher percentage of patients with pleural effusions or pneumothorax are being treated with small-bore (10-14 F) chest tubes rather than large-bore (>20 F). However, there are very few randomized controlled studies comparing the efficacy and complication rates with the small- and large-bore catheters. Moreover, the randomized trials that are available have flaws in their design. The advantages of the small-bore catheters are that they are easier to insert and there is less pain with their insertion while they are in place. The placement of the small-bore catheters is probably more optimal when placement is done with ultrasound guidance. Small-bore chest tubes are recommended when pleurodesis is performed. The success of the small-bore indwelling tunnelled catheters that are left in place for weeks documents that the small-bore tubes do not commonly become obstructed with fibrin. Patients with complicated parapneumonic effusions are probably best managed with small-bore catheters even when the pleural fluid is purulent. Patients with haemothorax are best managed with large-bore catheters because of blood clots and the high volume of pleural fluid. Most patients with pneumothorax can be managed with aspiration or small-bore chest tubes. If these fail, a large-bore chest tube may be necessary. Patients on mechanical ventilation with barotrauma induced pneumothoraces are best managed with large-bore chest tubes.

  12. Steroid use is associated with pneumonia in pediatric chest trauma.

    PubMed

    Williams, M D; Reckard, P E; Knox, R; Petersen, S R; Schiller, W R

    1992-04-01

    A review of pediatric trauma focused on pediatric chest injuries was performed at a trauma center specializing in neurologic trauma. Eighty of 342 (23%) pediatric trauma patients admitted to the center had chest injuries. Age, gender, mechanism of injury, magnitude of injury, incidence of pulmonary infection, chest tube usage, endotracheal intubation, steroid or antibiotic usage, morbidity, and mortality data were reviewed. Sixteen of 78 children (20%) with chest injuries developed pulmonary infections and were compared with the noninfected group. Patients with pneumonia had a higher morbidity with significantly longer mean hospital stay (43.0 vs. 12.7 days; p = 0.001), duration of intubation (8.4 vs. 1.5 days; p = 0.001), and total days with chest tubes, (2.2 vs. 1.4 days; p = 0.02). Pneumonia was significantly associated with longer mean duration of steroid usage (6.4 vs. 0.8 days; p = 0.0001). Duration of steroid administration for the treatment of concomitant brain injury was a significant independent risk factor for the occurrence of pneumonia.

  13. Chest wall, lung, and pleural space trauma.

    PubMed

    Miller, Lisa A

    2006-03-01

    Chest radiographs frequently underestimate the severity and extent of chest trauma and, in some cases, fail to detect the presence of injury. CT is more sensitive than chest radiography in the detection of pulmonary, pleural, and osseous abnormalities in the patient who has chest trauma. With the advent of multidetector CT (MDCT), high-quality multiplanar reformations are obtained easily and add to the diagnostic capabilities of MDCT. This article reviews the radiographic and CT findings of chest wall, pleural, and pulmonary injuries that are seen in the patient who has experienced blunt thoracic trauma.

  14. Chest wall angiolipoma complicating von Recklinghausen disease.

    PubMed

    Komatsu, Teruya; Takahashi, Koji; Fujinaga, Takuji

    2013-09-01

    We present the case of an 18-year-old man with chest wall angiolipoma and a medical history of von Recklinghausen neurofibromatosis. The chest wall tumor was originally detected during an evaluation for chest pain. For diagnostic and therapeutic purposes, video-assisted thoracoscopic resection was performed, and the tumor was histopathologically confirmed to be an angiolipoma. Chest wall angiolipoma is exceptionally rare. Only two cases have been reported in the English literature, with no reports regarding chest wall angiolipoma in a patient with von Recklinghausen disease.

  15. Micromechanical finite-element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone-hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering.

    PubMed

    Eshraghi, Shaun; Das, Suman

    2012-08-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite-element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30 vol.% HA. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30, respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical FEA model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any HA loading to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. The results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient- and site-specific composite tissue-engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing. PMID:22522129

  16. Penetrating wounds to the anterior chest. Analysis of thoracotomy and laparotomy.

    PubMed

    Borlase, B C; Metcalf, R K; Moore, E E; Manart, F D

    1986-12-01

    This study of the records of 193 consecutive patients admitted for penetrating anterior chest wounds was carried out to specifically define the need for emergent thoracotomy or laparotomy. The mechanism of injury was a stab wound in 119 patients and a gunshot wound in 74 patients. Seventy-three of the patients (38 percent) required either early thoracotomy (21 percent) or laparotomy (17 percent). In the upper chest region, 83 percent of the operations were thoracotomies, whereas in the lower chest region, 81 percent were laparotomies. Pericardial tamponade, chest tube output, and hypovolemic shock comprised 91 percent of the decisive signs for thoracotomy. The predominant reason for laparotomy was diagnostic peritoneal lavage (63 percent of patients). Plain abdominal roentgenograms were helpful to confirm diaphragmatic missile traverse. Our findings support selective operative management of anterior chest wounds as guided by injury mechanism and entrance location. PMID:3789289

  17. The effect of the duration of mechanical stimulation and post-stimulation culture on the structure and properties of dynamically compressed tissue-engineered menisci.

    PubMed

    Puetzer, Jennifer L; Ballyns, Jeffrey J; Bonassar, Lawrence J

    2012-07-01

    This study investigated the hypothesis that timing and duration of dynamic compression are integral to regulating extracellular matrix (ECM) assembly of tissue-engineered (TE) menisci. The goal of this study was to examine the effects of varying load and static culture duration on structure, composition, and mechanical properties of TE menisci. We accomplished this by varying the duration of dynamic loading over 4 weeks of culture, and by examining increasing periods of static culture after 2 weeks of dynamic loading. Bovine meniscal fibrochondrocytes were seeded into 2% w/v alginate, crosslinked with CaSO(4), injected into anatomical micro-computed tomography-based molds, and post-crosslinked with CaCl(2). Meniscal constructs were dynamically compressed three times a week via a custom bioreactor for a total of 2 h, with an hour of rest between loading cycles, for 1, 2, or 4 weeks. They were then placed in static culture. After 4 weeks of culture, increased load duration was found to be beneficial to matrix formation and mechanical properties, with superior mechanical and biochemical properties in samples loaded for 2 or 4 weeks. Further, the mechanical properties of these constructs were similar, suggesting that the additional 2 weeks of loading may not be necessary. Samples loaded for 2 weeks followed by a 4-week static culture period yielded the most mature matrix with significant improvements in collagen bundle formation, 2.8-fold increase in the glycosaminoglycan content, 2-fold increase in the collagen content, and 4.3-fold increase in the compressive equilibrium modulus. Overall, this study demonstrated the importance of timing and duration of loading. By switching to prolonged static culture after 2 weeks of loading, we decreased the amount of ECM lost to the media, while significantly increasing biochemical and mechanical properties of TE menisci. PMID:22429287

  18. Major chest wall reconstruction after chest wall irradiation

    SciTech Connect

    Larson, D.L.; McMurtrey, M.J.; Howe, H.J.; Irish, C.E.

    1982-03-15

    In the last year, 12 patients have undergone extensive chest wall resection. Eight patients had recurrent cancer after prior resection and irradiation with an average defect of 160 square centimeters, usually including ribs and a portion of the sternum; four had radionecrosis of soft tissue and/or bone. Methods of reconstruction included latissimus dorsi musculocutaneous (MC) flap (five patients), pectoralis major MC flap (seven patients), and omental flap and skin graft (one patient). The donor site was usually closed primarily. All flaps survived providing good wound coverage. The only complication was partial loss of a latissimus dorsi MC flap related to an infected wound; this reconstruction was salvaged with a pectoralis major MC flap. The hospital stay ranged from 10-25 days with a median stay of 11 days. Use of the MC flap is a valuable tool which can be used to significantly decrease morbidity, hospital stay, and patient discomfort related to the difficult problem of chest wall reconstruction after radiation therapy.

  19. Compression embedding

    DOEpatents

    Sandford, II, Maxwell T.; Handel, Theodore G.; Bradley, Jonathan N.

    1998-01-01

    A method and apparatus for embedding auxiliary information into the digital representation of host data created by a lossy compression technique and a method and apparatus for constructing auxiliary data from the correspondence between values in a digital key-pair table with integer index values existing in a representation of host data created by a lossy compression technique. The methods apply to data compressed with algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as ordered sequences of blocks containing integer indices having redundancy and uncertainty of value by one unit, allowing indices which are adjacent in value to be manipulated to encode auxiliary data. Also included is a method to improve the efficiency of lossy compression algorithms by embedding white noise into the integer indices. Lossy compression methods use loss-less compression to reduce to the final size the intermediate representation as indices. The efficiency of the loss-less compression, known also as entropy coding compression, is increased by manipulating the indices at the intermediate stage. Manipulation of the intermediate representation improves lossy compression performance by 1 to 10%.

  20. Compression embedding

    DOEpatents

    Sandford, M.T. II; Handel, T.G.; Bradley, J.N.

    1998-07-07

    A method and apparatus for embedding auxiliary information into the digital representation of host data created by a lossy compression technique and a method and apparatus for constructing auxiliary data from the correspondence between values in a digital key-pair table with integer index values existing in a representation of host data created by a lossy compression technique are disclosed. The methods apply to data compressed with algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as ordered sequences of blocks containing integer indices having redundancy and uncertainty of value by one unit, allowing indices which are adjacent in value to be manipulated to encode auxiliary data. Also included is a method to improve the efficiency of lossy compression algorithms by embedding white noise into the integer indices. Lossy compression methods use loss-less compression to reduce to the final size the intermediate representation as indices. The efficiency of the loss-less compression, known also as entropy coding compression, is increased by manipulating the indices at the intermediate stage. Manipulation of the intermediate representation improves lossy compression performance by 1 to 10%. 21 figs.

  1. [Chest modelling and automotive accidents].

    PubMed

    Trosseille, Xavier

    2011-11-01

    Automobile development is increasingly based on mathematical modeling. Accurate models of the human body are now available and serve to develop new means of protection. These models used to consist of rigid, articulated bodies but are now made of several million finite elements. They are now capable of predicting some risks of injury. To develop these models, sophisticated tests were conducted on human cadavers. For example, chest modeling started with material characterization and led to complete validation in the automobile environment. Model personalization, based on medical imaging, will permit studies of the behavior and tolerances of the entire population.

  2. Ex Vivo bone formation in bovine trabecular bone cultured in a dynamic 3D bioreactor is enhanced by compressive mechanical strain.

    PubMed

    David, Valentin; Guignandon, Alain; Martin, Aline; Malaval, Luc; Lafage-Proust, Marie-Hélène; Rattner, Aline; Mann, Val; Noble, Brendon; Jones, David B; Vico, Laurence

    2008-01-01

    Our aim was to test cell and trabecular responses to mechanical loading in vitro in a tissue bone explant culture model. We used a new three-dimensional culture model, the ZetOS system, which provides the ability to exert cyclic compression on cancellous bone cylinders (bovine sternum) cultured in forced flow circumfusion chambers, and allows to assess mechanical parameters of the cultivated samples. We evaluated bone cellular parameters through osteocyte viability test, gene and protein expression, and histomorphometric bone formation rate, in nonloaded versus loaded samples. The microarchitecture of bone cores was appraised by in vivo micro-CT imaging. After 3 weeks, the samples receiving daily cyclic compression exhibited increased osteoblast differentiation and activity associated with thicker, more plate-like-shaped trabeculae and higher Young's modulus and ultimate force as compared to unloaded samples. Osteoclast activity was not affected by mechanical strain, although it was responsive to drug treatments (retinoic acid and bisphosphonate) during the first 2 weeks of culture. Thus, in the ZetOS apparatus, we reproduce in vitro the osteogenic effects of mechanical strain known in vivo, making this system a unique and an essential laboratory aid for ex vivo testing of lamellar bone remodeling.

  3. Compression embedding

    DOEpatents

    Sandford, M.T. II; Handel, T.G.; Bradley, J.N.

    1998-03-10

    A method of embedding auxiliary information into the digital representation of host data created by a lossy compression technique is disclosed. The method applies to data compressed with lossy algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as integer indices having redundancy and uncertainty in value by one unit. Indices which are adjacent in value are manipulated to encode auxiliary data. By a substantially reverse process, the embedded auxiliary data can be retrieved easily by an authorized user. Lossy compression methods use loss-less compressions known also as entropy coding, to reduce to the final size the intermediate representation as indices. The efficiency of the compression entropy coding, known also as entropy coding is increased by manipulating the indices at the intermediate stage in the manner taught by the method. 11 figs.

  4. Compression embedding

    DOEpatents

    Sandford, II, Maxwell T.; Handel, Theodore G.; Bradley, Jonathan N.

    1998-01-01

    A method of embedding auxiliary information into the digital representation of host data created by a lossy compression technique. The method applies to data compressed with lossy algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as integer indices having redundancy and uncertainty in value by one unit. Indices which are adjacent in value are manipulated to encode auxiliary data. By a substantially reverse process, the embedded auxiliary data can be retrieved easily by an authorized user. Lossy compression methods use loss-less compressions known also as entropy coding, to reduce to the final size the intermediate representation as indices. The efficiency of the compression entropy coding, known also as entropy coding is increased by manipulating the indices at the intermediate stage in the manner taught by the method.

  5. Common errors in evaluating chest radiographs.

    PubMed

    Mann, H

    1990-01-01

    Chest radiographs that are correctly obtained and interpreted provide valuable diagnostic information. However, some radiographs are not taken at total lung capacity, and the appearance of the lungs on film may mimic certain lung disorders. Most common interpretive pitfalls in chest radiography can be avoided by physicians who are familiar with the film appearance of varying degrees of lung inflation, technical limitations of portable radiography, and common chest abnormalities. When further definition is necessary, additional projections should be obtained. Chest fluoroscopy and computed tomography can offer further clarification, if needed. PMID:2296566

  6. Atypical Chest Pain: An Unusual Presentation of Spinal Metastasis due to Penile Carcinoma

    PubMed Central

    Pywell, Sarah; Dott, Cameron; Khan, Mohammad Taimur; Sivanadarajah, Naveethan

    2016-01-01

    Spinal metastases may present in a myriad of ways, most commonly back pain with or without neurology. We report an unusual presentation of isolated atypical chest pain preceding metastatic cord compression, secondary to penile carcinoma. Spinal metastasis from penile carcinoma is rare with few cases reported. This unusual presentation highlights the need for a heightened level of clinical suspicion for spinal metastases as a possible cause for chest pain in any patients with a history of carcinoma. The case is discussed with reference to the literature. PMID:27429829

  7. An Analytical Solution for Mechanical Responses Induced by Temperature and Air Pressure in a Lined Rock Cavern for Underground Compressed Air Energy Storage

    NASA Astrophysics Data System (ADS)

    Zhou, Shu-Wei; Xia, Cai-Chu; Du, Shi-Gui; Zhang, Ping-Yang; Zhou, Yu

    2015-03-01

    Mechanical responses induced by temperature and air pressure significantly affect the stability and durability of underground compressed air energy storage (CAES) in a lined rock cavern. An analytical solution for evaluating such responses is, thus, proposed in this paper. The lined cavern of interest consists of three layers, namely, a sealing layer, a concrete lining and the host rock. Governing equations for cavern temperature and air pressure, which involve heat transfer between the air and surrounding layers, are established first. Then, Laplace transform and superposition principle are applied to obtain the temperature around the lined cavern and the air pressure during the operational period. Afterwards, a thermo-elastic axisymmetrical model is used to analytically determine the stress and displacement variations induced by temperature and air pressure. The developments of temperature, displacement and stress during a typical operational cycle are discussed on the basis of the proposed approach. The approach is subsequently verified with a coupled compressed air and thermo-mechanical numerical simulation and by a previous study on temperature. Finally, the influence of temperature on total stress and displacement and the impact of the heat transfer coefficient are discussed. This paper shows that the temperature sharply fluctuates only on the sealing layer and the concrete lining. The resulting tensile hoop stresses on the sealing layer and concrete lining are considerably large in comparison with the initial air pressure. Moreover, temperature has a non-negligible effect on the lined cavern for underground compressed air storage. Meanwhile, temperature has a greater effect on hoop and longitudinal stress than on radial stress and displacement. In addition, the heat transfer coefficient affects the cavern stress to a higher degree than the displacement.

  8. Compressive mechanical compatibility of anisotropic porous Ti6Al4V alloys in the range of physiological strain rate for cortical bone implant applications.

    PubMed

    Li, Fuping; Li, Jinshan; Kou, Hongchao; Huang, Tingting; Zhou, Lian

    2015-09-01

    Porous titanium and its alloys are believed to be promising materials for bone implant applications, since they can reduce the "stress shielding" effect by tailoring porosity and improve fixation of implant through bone ingrowth. In the present work, porous Ti6Al4V alloys for biomedical application were fabricated by diffusion bonding of alloy meshes. Compressive mechanical behavior and compatibility in the range of physiological strain rate were studied under quasi-static and dynamic conditions. The results show that porous Ti6Al4V alloys possess anisotropic structure with elongated pores in the out-of-plane direction. For porous Ti6Al4V alloys with 60-70 % porosity, more than 40 % pores are in the range of 200-500 μm which is the optimum pore size suited for bone ingrowth. Quasi-static Young's modulus and yield stress of porous Ti6Al4V alloys with 30-70 % relative density are in the range of 6-40 GPa and 100-500 MPa, respectively. Quasi-static compressive properties can be quantitatively tailored by porosity to match those of cortical bone. Strain rate sensitivity of porous Ti6Al4V alloys is related to porosity. Porous Ti6Al4V alloys with porosity higher than 50 % show enhanced strain rate sensitivity, which is originated from that of base materials and micro-inertia effect. Porous Ti6Al4V alloys with 60-70 % porosity show superior compressive mechanical compatibility in the range of physiological strain rate for cortical bone implant applications.

  9. Remote interpretation of chest roentgenograms.

    PubMed

    Andrus, W S; Hunter, C H; Bird, K T

    1975-04-01

    A series of 98 chest films was interpreted by two physicians on the basis of monitor display of the transmitted television signal representing the roentgenographic image. The transmission path was 14 miles long, and included one active repeater station. Receiver operating characteristic curves were drawn to compare interpretations rendered on television view of the image with classic, direct view interpretations of the same films. Performance in these two viewing modes was found to be quite similar. When films containing only hazy densities lacking internal structure or sharp margins, were removed from the sample, interpretation of the remaining films was essentially identical via the two modes. Since hazy densities are visible on retrospective examination, interpretation of roentgenograms at a distance via television appears to be a feasible route for delivery of radiologic services.

  10. Coronary artery dissection after blunt chest trauma

    PubMed Central

    Shamsi, Fahad; Tai, Javed Majid; Bokhari, Saira

    2014-01-01

    Blunt thoracic trauma may result in cardiac injuries ranging from simple arrhythmias to fatal cardiac rupture. Coronary artery dissection culminating in acute myocardial infarction (AMI) is rare after blunt chest trauma. Here we report a case of a 37-year-old man who had an AMI secondary to coronary dissection resulting from blunt chest trauma after involvement in a physical fight. PMID:25246456

  11. [Wooden chests for the midwife's equipment].

    PubMed

    Carlén-Nilsson, C

    1993-01-01

    In the museum of medical history in Lund there are several wooden chests containing partly identical instruments apparently belonging to a midwife. The instruments dated from before 1900, e.g. lancets and horn cups for blood-letting, a pewter enema syringe, a wooden stethoscope, a "tobacco pipe" and glass bottles. The use of the tobacco pipe was first puzzling, but it appeared to be a breast reliver. What do we know about the date of the chests? One chest has belonged to Kjersti Nilsdotter, a midwife educated in Lund 1872-1873. Her certificate was in the chest. From Ronnie Hunt, Minnesota we have got information about another chest of the same type. That belonged to Nelly Gustafsson, a midwife educated in Lund probably about 1870. She emigrated to USA and was a practising midwife in Lindstrom, Minnesota from about 1900.

  12. [Wooden chests for the midwife's equipment].

    PubMed

    Carlén-Nilsson, C

    1993-01-01

    In the museum of medical history in Lund there are several wooden chests containing partly identical instruments apparently belonging to a midwife. The instruments dated from before 1900, e.g. lancets and horn cups for blood-letting, a pewter enema syringe, a wooden stethoscope, a "tobacco pipe" and glass bottles. The use of the tobacco pipe was first puzzling, but it appeared to be a breast reliver. What do we know about the date of the chests? One chest has belonged to Kjersti Nilsdotter, a midwife educated in Lund 1872-1873. Her certificate was in the chest. From Ronnie Hunt, Minnesota we have got information about another chest of the same type. That belonged to Nelly Gustafsson, a midwife educated in Lund probably about 1870. She emigrated to USA and was a practising midwife in Lindstrom, Minnesota from about 1900. PMID:11639439

  13. Intercostal hemangioma of the chest wall

    PubMed Central

    Hamzík, Julian

    2016-01-01

    The authors describe a case of a 36-year-old patient who had six months’ pain of the thoracic spine and left chest. A soft slowly growing resistance was present on the dorso-lateral side of the left chest wall, in the range of the seventh to ninth rib. According to the medical history, the patient did not have any prior trauma and malignancy. A well-defined tumor of the left chest wall with calcifications, which grew to the seventh and eighth intercostal space, was present on computed tomography (CT) and magnetic resonance (MR) scans. The patient underwent resection of the tumor with the chest wall and reconstruction with polypropylene mesh. Histologically, it was a venous hemangioma, one of very rare tumors of the chest wall. PMID:27212983

  14. Chest pain in a young basketball player.

    PubMed

    Campbell, Catherine Y; Record, Janet D; Kolandaivelu, Aravindan; Ziegelstein, Roy C

    2006-06-01

    A 32-year-old man was elbowed in the chest while fighting for a rebound in a recreational basketball game. He fell to the ground and his chest ached from the blow. Four days later he developed more severe chest pressure with dyspnea and came to the hospital. His chest wall was tender and his pulse slow, but the remainder of his physical examination was normal. Electrocardiogram showed sinus bradycardia, first-degree atrioventricular (AV) block, and occasional isorhythmic AV dissociation, but no ischemic ST-T changes. Cardiac troponin I rose to 1.74 ng/mL (normal <0.50). The patient therefore underwent coronary angiography, showing spiral dissection of the right coronary artery with extensive thrombus filling the distal portion of the vessel. Stenting was unsuccessful in restoring flow. This case highlights the potential dangers of blunt chest trauma in recreational sports and shows how angiography can distinguish myocardial contusion from coronary artery dissection.

  15. Left Main Ostial Compression in a Patient with Pulmonary Hypertension: Dynamic Findings by IVUS

    PubMed Central

    Seabra, Luciana F.; Ribeiro, Henrique B.; de Barros e Silva, Pedro Gabriel Melo; Rodrigues, Marcelo J.; Spadaro, André G.; Conejo, Fábio; Godinho, Roger R.; Faig, Sandro M. M.; de Macedo, Thiago Andrade; de P. S. Baptista, Luciana; de Resende, Marcos Valerio C.; Furlan, Valter; Ribeiro, Expedito E.

    2015-01-01

    Patient: Female, 39 Final Diagnosis: Idiopathic pulmonary arterial hypertension Symptoms: Chest pain Medication: — Clinical Procedure: Percutaneous coronary intervention Specialty: Cardiology and Pulmonology Objective: Rare co-existance of disease or pathology Background: Pulmonary artery dilatation is a common feature among patients with severe pulmonary hypertension. Left main coronary artery extrinsic compression by an enlarged pulmonary artery is a rare complication and a potential cause for chest pain and sudden cardiac death in patients with pulmonary hypertension. This situation is very rare and few reports have described it. Currently, the appropriate management of these patients remains unknown. Case Report: In the present report we describe the case of a 39-year-old woman who presented with a 2-year history of cardiac symptoms related to exercise. The patient underwent a 64-slice multidetector computed tomography (MDCT) coronary angiography, which showed left main coronary artery (LMCA) compression by a markedly enlarged pulmonary artery trunk (44 mm), without intraluminal stenosis or coronary artery calcium, as determined by the Agatston score. This compression was considered to be the cause of the cardiac symptoms. To confirm and plan the treatment, the patient underwent cardiac catheterization that confirmed the diagnosis of pulmonary hypertension and LMCA critical obstruction. Taking into account the paucity of information regarding the best management in these cases, the treatment decision was shared among a “heart team” that chose percutaneous coronary intervention with stent placement. An intra-vascular ultrasound was performed during the procedure, which showed a dynamic compression of the left main coronary artery. The intervention was successfully executed without any adverse events. Conclusions: This case illustrates dynamic compression of the LMCA by IVUS, visually demonstrating the mechanism of the intermittent symptoms of myocardial

  16. Thermal stability and relaxation mechanisms in compressively strained Ge0.94Sn0.06 thin films grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Fleischmann, C.; Lieten, R. R.; Hermann, P.; Hönicke, P.; Beckhoff, B.; Seidel, F.; Richard, O.; Bender, H.; Shimura, Y.; Zaima, S.; Uchida, N.; Temst, K.; Vandervorst, W.; Vantomme, A.

    2016-08-01

    Strained Ge1-xSnx thin films have recently attracted a lot of attention as promising high mobility or light emitting materials for future micro- and optoelectronic devices. While they can be grown nowadays with high crystal quality, the mechanism by which strain energy is relieved upon thermal treatments remains speculative. To this end, we investigated the evolution (and the interplay) of composition, strain, and morphology of strained Ge0.94Sn0.06 films with temperature. We observed a diffusion-driven formation of Sn-enriched islands (and their self-organization) as well as surface depressions (pits), resulting in phase separation and (local) reduction in strain energy, respectively. Remarkably, these compositional and morphological instabilities were found to be the dominating mechanisms to relieve energy, implying that the relaxation via misfit generation and propagation is not intrinsic to compressively strained Ge0.94Sn0.06 films grown by molecular beam epitaxy.

  17. The modified cam clay model for constrained compression of human morsellised bone: effects of porosity on the mechanical behaviour.

    PubMed

    Lunde, Knut B; Skallerud, Bjørn

    2009-01-01

    Morsellised cortico-cancellous bone (MCB) is often used in revision surgery for filling skeletal defects. The MCB porosity is found to influence the degree of bone ingrowth. Thus expressing a material model in terms of porosity may be attractive from a clinical point of view. We analysed the moisture content and performed constrained compression testing of human impacted and unimpacted MCB, in order to determine material parameters for the common constitutive soil model: modified cam clay. The model seemed to be suitable for the unimpacted pellets with a logarithmic bulk modulus kappa=0.059+/-0.0019 and a logarithmic hardening constant lambda=0.36+/-0.014. This model, relating the specific volume (and porosity) to the logarithm of stress, may be suited to find the best compromise of stiffness and porosity for MCB. PMID:19627806

  18. Painful palpitations: chest pain associated with postextrasystolic ST depression.

    PubMed

    Ul Haq, Ehtesham; Kleyn, Emile; Omar, Bassam

    2014-01-01

    Postextrasystolic T-wave changes have been described as early as 1915. The significance and mechanism of such changes remain controversial. Because postextrasystolic ST changes are rare, much of the ensuing discussion concentrates on the closely related and more commonly reported phenomenon of postextrasystolic T-wave inversion. This report documents the case of a 67-year-old man with a history of coronary artery disease who was admitted to the hospital with chest pain. PMID:25662929

  19. Evaluation of damage progression and mechanical behavior under compression of bone cements containing core-shell nanoparticles by using acoustic emission technique.

    PubMed

    Pacheco-Salazar, O F; Wakayama, Shuichi; Sakai, Takenobu; Cauich-Rodríguez, J V; Ríos-Soberanis, C R; Cervantes-Uc, J M

    2015-06-01

    In this work, the effect of the incorporation of core-shell particles on the fracture mechanisms of the acrylic bone cements by using acoustic emission (AE) technique during the quasi-static compression mechanical test was investigated. Core-shell particles were composed of a poly(butyl acrylate) (PBA) rubbery core and a methyl methacrylate/styrene copolymer (P(MMA-co-St)) outer glassy shell. Nanoparticles were prepared with different core-shell ratio (20/80, 30/70, 40/60 and 50/50) and were incorporated into the solid phase of bone cement at several percentages (5, 10 and 15 wt%). It was observed that the particles exhibited a spherical morphology averaging ca. 125 nm in diameter, and the dynamic mechanical analysis (DMA) thermograms revealed the desired structuring pattern of phases associated with core-shell structures. A fracture mechanism was proposed taking into account the detected AE signals and the scanning electron microscopy (SEM) micrographs. In this regard, core-shell nanoparticles can act as both additional nucleation sites for microcracks (and crazes) and to hinder the microcrack propagation acting as a barrier to its growth; this behavior was presented by all formulations. Cement samples containing 15 wt% of core-shell nanoparticles, either 40/60 or 50/50, were fractured at 40% deformation. This fact seems related to the coalescence of microcracks after they surround the agglomerates of core-shell nanoparticles to continue growing up. This work also demonstrated the potential of the AE technique to be used as an accurate and reliable detection tool for quasi-static compression test in acrylic bone cements.

  20. Traumatic aortic regurgitation combined with descending aortic pseudoaneurysm secondary to blunt chest trauma.

    PubMed

    Kim, Siho; Park, Joon Suk; Yoo, Seung Min; Kim, Kyung Ho; Yang, Woo-In; Sung, Jung-Hoon; Kim, In Jai; Lim, Sang-Wook; Cha, Dong-Hun; Moon, Jae-Youn

    2014-09-23

    Rupture of the aorta is a relatively rare complication of blunt chest trauma, and traumatic rupture of the aortic valve is even rarer. Even though both result from blunt chest trauma, the causative mechanisms of aortic valve injury differ from those of descending aortic rupture. There are no previous reports in the literature of simultaneous injuries to both the descending aorta and the aortic valve. We report a case of a 70-year-old man who presented with traumatic aortic regurgitation combined with traumatic pseudoaneurysm of the aortic isthmus following blunt chest trauma, and its successful repair with a hybrid surgical strategy.

  1. Hitherto unknown shear rupture mechanism as a source of instability in intact hard rocks at highly confined compression

    NASA Astrophysics Data System (ADS)

    Tarasov, Boris G.

    2014-05-01

    Today, frictional shear resistance along pre-existing faults is considered to be the lower limit on rock shear strength for confined conditions corresponding to the seismogenic layer. This paper introduces a recently identified shear rupture mechanism providing a paradoxical feature of hard rocks - the possibility of shear rupture propagation through the highly confined intact rock mass at shear stress levels significantly less than frictional strength. In the new mechanism, the rock failure associated with consecutive creation of small slabs (known as ‘domino-blocks') from the intact rock in the rupture tip is driven by a fan-shaped domino structure representing the rupture head. The fan-head combines such unique features as: extremely low shear resistance, self-sustaining stress intensification, and self-unbalancing conditions. Due to this the failure process caused by the mechanism is very dynamic and violent. This makes it impossible to directly observe and study the mechanism and can explain why the mechanism has not been detected before. This paper provides physical motivation for the mechanism, based upon side effects accompanying the failure process. Physical and mathematical models of the mechanism presented in the paper explain unique and paradoxical features of the mechanism. The new shear rupture mechanism allows a novel point of view for understanding the nature of spontaneous failure processes in hard rocks including earthquakes.

  2. [A rare case of chest pain].

    PubMed

    Bodócsi, Beáta; Koncz, István; Hum, Zsigmond; Serfőző, Orsolya; Pap-Szekeres, József; Szabó, István

    2016-09-01

    Chest pain is a common symptom in patients who visit Emergency Departments. The main task is to exclude life-threatening diseases such as acute coronary syndrome, pulmonary embolization and dissection of thoracic aorta. The authors present the history of a patient, who had an intense chest pain for 7 hours. In accordance with the diagnostic algorithm of chest pain, ECG, blood collection, chest X-ray and chest computed tomography angiography were performed. Acute coronary syndrome, pulmonary embolization and dissection of the thoracic aorta were excluded, however, chest computed tomography CT revealed a huge hiatal hernia as an incidental finding. An emergency surgical repair was performed and the patient recovered without any complications. The authors emphasize that the diagnostic algorithms focus on the confirmation or rejection of possible life threatening diseases in case of chest pain. However, it should be kept in mind that rarer causes may occur, which may require involvement of the relevant disciplines and multidisciplinary thinking. Orv. Hetil., 2016, 157(36), 1445-1448. PMID:27596512

  3. Radioprotective effect of N-acetyl-L-cysteine free radical scavenger on compressive mechanical properties of the gamma sterilized cortical bone of bovine femur.

    PubMed

    Allaveisi, Farzaneh; Hashemi, Bijan; Mortazavi, Seyed Mohammad Javad

    2015-03-01

    Gamma sterilization of bone allografts is used as a gold standard method to provide safety against disease transmission. However, it is well documented that high dose levels of ionizing radiation can degrade bone mechanical properties. This effect, which is attributed to the formation of free radicals through radiolysis of the water content of collagen, can lead to post-implantation difficulties such as pre-failure and/or secondary fractures of bone allografts. Recently, treatment of irradiated allografts with free radical scavengers is used to protect them against radiation-induced damages. This study aimed to investigate the radioprotective role of N-acetyl-L-cysteine (NAC) during the gamma sterilization of the cortical bone of bovine femurs using the compressive test. Totally, 195 cubic specimens with a dimension of 5 × 5 × 3 cubic mm were divided into 13 groups including a control and 12 experimental groups exposed to 18, 36, and 70 kGy at three different NAC concentrations (1.25, 12.5, and 25 mM for 18 kGy; 5, 50, and 100 mM for 36 kGy; 10, 100, and 200 mM for 70 kGy). The mechanical behavior of the sterilized specimens was studied using the uniaxial compressive test. The results indicated a concentration-dependent radioprotection effect of NAC on the plastic properties of the cortical bones. The concentration dependency of NAC was in turn related to radiation dose levels. In conclusion, treatment of bone specimens with a characteristic concentration of NAC during exposure to specific radiation dose levels can provide an efficient radioprotection window for preserving the mechanical stability of gamma sterilized allografts. PMID:24737302

  4. Impact of acid and alkaline pretreatments on the molecular network of wheat gluten and on the mechanical properties of compression-molded glassy wheat gluten bioplastics.

    PubMed

    Jansens, Koen J A; Lagrain, Bert; Brijs, Kristof; Goderis, Bart; Smet, Mario; Delcour, Jan A

    2013-10-01

    Wheat gluten can be converted into rigid biobased materials by high-temperature compression molding at low moisture contents. During molding, a cross-linked protein network is formed. This study investigated the effect of mixing gluten with acid/alkali in 70% ethanol at ambient temperature for 16 h followed by ethanol removal, freeze-drying, and compression molding at 130 and 150 °C on network formation and on types of cross-links formed. Alkaline pretreatment (0-100 mmol/L sodium hydroxide or 25 mmol/L potassium hydroxide) strongly affected gluten cross-linking, whereas acid pretreatment (0-25 mmol/L sulfuric acid or 25 mmol/L hydrochloric acid) had limited effect on the gluten network. Molded alkaline-treated gluten showed enhanced cross-linking but also degradation when treated with high alkali concentrations, whereas acid treatment reduced gluten cross-linking. β-Elimination of cystine and lanthionine formation occurred more pronouncedly at higher alkali concentrations. In contrast, formation of disulfide and nondisulfide cross-links during molding was hindered in acid-pretreated gluten. Bioplastic strength was higher for alkali than for acid-pretreated samples, whereas the flexural modulus was only slightly affected by either alkaline or acid pretreatment. Apparently, the ratio of disulfide to nondisulfide cross-links did not affect the mechanical properties of rigid gluten materials.

  5. Impact of acid and alkaline pretreatments on the molecular network of wheat gluten and on the mechanical properties of compression-molded glassy wheat gluten bioplastics.

    PubMed

    Jansens, Koen J A; Lagrain, Bert; Brijs, Kristof; Goderis, Bart; Smet, Mario; Delcour, Jan A

    2013-10-01

    Wheat gluten can be converted into rigid biobased materials by high-temperature compression molding at low moisture contents. During molding, a cross-linked protein network is formed. This study investigated the effect of mixing gluten with acid/alkali in 70% ethanol at ambient temperature for 16 h followed by ethanol removal, freeze-drying, and compression molding at 130 and 150 °C on network formation and on types of cross-links formed. Alkaline pretreatment (0-100 mmol/L sodium hydroxide or 25 mmol/L potassium hydroxide) strongly affected gluten cross-linking, whereas acid pretreatment (0-25 mmol/L sulfuric acid or 25 mmol/L hydrochloric acid) had limited effect on the gluten network. Molded alkaline-treated gluten showed enhanced cross-linking but also degradation when treated with high alkali concentrations, whereas acid treatment reduced gluten cross-linking. β-Elimination of cystine and lanthionine formation occurred more pronouncedly at higher alkali concentrations. In contrast, formation of disulfide and nondisulfide cross-links during molding was hindered in acid-pretreated gluten. Bioplastic strength was higher for alkali than for acid-pretreated samples, whereas the flexural modulus was only slightly affected by either alkaline or acid pretreatment. Apparently, the ratio of disulfide to nondisulfide cross-links did not affect the mechanical properties of rigid gluten materials. PMID:24016229

  6. Chest pain: a time for concern?

    PubMed

    King, Joan E; Magdic, Kathy S

    2014-01-01

    When a patient complains of chest pain, the first priority is to establish whether the situation is life threatening. Life-threatening differential diagnoses that clinicians must consider include acute coronary syndrome, cardiac tamponade, pulmonary embolus, aortic dissection, and tension pneumothorax. Nonthreatening causes of chest pain that should be considered include spontaneous pneumothorax, pleural effusion, pneumonia, valvular diseases, gastric reflux, and costochondritis. The challenge for clinicians is not to be limited by "satisfaction of search" and fail to consider important differential diagnoses. The challenge, however, can be met by developing a systematic method to assess chest pain that will lead to the appropriate diagnosis and appropriate treatment plan.

  7. Technique for chest radiography for pneumoconiosis

    SciTech Connect

    Sargent, E.N.

    1982-01-01

    Routine radiographic chest examinations have been performed using a variety of techniques. Although chest radiography is one of the most commonly performed radiographic examinations, it is often difficult to obtain consistently good quality roentgenograms. This publication provides a simple guide and relatively easy solution to the many problems that radiologic technologists might encounter. The language is purposely relatively simple and care has been taken to avoid difficult mathematical and physical explanations. The intent is to provide an easily referrable text for those who may encounter difficulties in producing acceptable chest radiographs.

  8. [Lateral chest X-rays. Radiographic anatomy].

    PubMed

    García Villafañe, C; Pedrosa, C S

    2014-01-01

    Lateral chest views constitute an essential part of chest X-ray examinations, so it is fundamental to know the anatomy on these images and to be able to detect the variations manifested on these images in different diseases. The aim of this article is to review the normal anatomy and main normal variants seen on lateral chest views. For teaching purposes, we divide the thorax into different spaces and analyze each in an orderly way, especially emphasizing the anatomic details that are most helpful for locating lesions that have already been detected in the posteroanterior view or for detecting lesions that can be missed in the posteroanterior view.

  9. Grain size dependence of dynamic mechanical behavior of AZ31B magnesium alloy sheet under compressive shock loading

    SciTech Connect

    Asgari, H.; Odeshi, A.G.; Szpunar, J.A.; Zeng, L.J.; Olsson, E.

    2015-08-15

    The effects of grain size on the dynamic deformation behavior of rolled AZ31B alloy at high strain rates were investigated. Rolled AZ31B alloy samples with grain sizes of 6, 18 and 37 μm, were subjected to shock loading tests using Split Hopkinson Pressure Bar at room temperature and at a strain rate of 1100 s{sup −} {sup 1}. It was found that a double-peak basal texture formed in the shock loaded samples. The strength and ductility of the alloy under the high strain-rate compressive loading increased with decreasing grain size. However, twinning fraction and strain hardening rate were found to decrease with decreasing grain size. In addition, orientation imaging microscopy showed a higher contribution of double and contraction twins in the deformation process of the coarse-grained samples. Using transmission electron microscopy, pyramidal dislocations were detected in the shock loaded sample, proving the activation of pyramidal slip system under dynamic impact loading. - Highlights: • A double-peak basal texture developed in all shock loaded samples. • Both strength and ductility increased with decreasing grain size. • Twinning fraction and strain hardening rate decreased with decreasing grain size. • ‘g.b’ analysis confirmed the presence of dislocations in shock loaded alloy.

  10. Alternative Compression Garments

    NASA Technical Reports Server (NTRS)

    Stenger, M. B.; Lee, S. M. C.; Ribeiro, L. C.; Brown, A. K.; Westby, C. M.; Platts, S. H.

    2011-01-01

    Orthostatic intolerance after spaceflight is still an issue for astronauts as no in-flight countermeasure has been 100% effective. Future anti-gravity suits (AGS) may be similar to the Shuttle era inflatable AGS or may be a mechanical compression device like the Russian Kentavr. We have evaluated the above garments as well as elastic, gradient compression garments of varying magnitude and determined that breast-high elastic compression garments may be a suitable replacement to the current AGS. This new garment should be more comfortable than the AGS, easy to don and doff, and as effective a countermeasure to orthostatic intolerance. Furthermore, these new compression garments could be worn for several days after space flight as necessary if symptoms persisted. We conducted two studies to evaluate elastic, gradient compression garments. The purpose of these studies was to evaluate the comfort and efficacy of an alternative compression garment (ACG) immediately after actual space flight and 6 degree head-down tilt bed rest as a model of space flight, and to determine if they would impact recovery if worn for up to three days after bed rest.

  11. Mechanical behaviors and failure processes of precracked specimens under uniaxial compression: A perspective from microscopic displacement patterns

    NASA Astrophysics Data System (ADS)

    Liu, Ting; Lin, Baiquan; Zou, Quanle; Zhu, Chuanjie; Yan, Fazhi

    2016-03-01

    Hydraulic slotting is an efficient permeability enhancement method that has been widely used in China for enhanced coalbed methane (ECBM) recovery. Although some research has been conducted on hydraulic slotting, the mechanical behaviors such as strength, deformation, and cracking processes of coal treated by this technique are still unclear. This paper numerically investigates the mechanical behaviors of specimens containing combined flaws with various inclination angles. Research results show that different flaw inclination angles result in variations in strength and deformation of precracked specimens. We also analyzed the crack initiation, propagation, and coalescence processes to understand the underlying mechanisms for the aforementioned variations. To evaluate the crack initiation and propagation process and its corresponding mechanisms, we proposed 12 types of displacement field modes from the perspective of particles relative motion. Based on this, evolution of the displacement field during loading process is analyzed and 11 types of crack and three types of crack initiation modes are extracted from the cracking processes of specimens with different inclination angles. Analysis of the displacement field not only indicates the type of each crack, but also reveals the formation mechanism of the three crack initiation modes. A comparison between the numerical results and the previous laboratory test results shows that numerical simulation can reproduce most of the phenomenon observed in the laboratory test. The research result is expected to contribute to the further understanding of the mechanical behavior of coal subjected to hydraulic slotting or the stability of rock structures.

  12. Diagnostic Yield of Recommendations for Chest CT Examination Prompted by Outpatient Chest Radiographic Findings

    PubMed Central

    Harvey, H. Benjamin; Gilman, Matthew D.; Wu, Carol C.; Cushing, Matthew S.; Halpern, Elkan F.; Zhao, Jing; Pandharipande, Pari V.; Shepard, Jo-Anne O.

    2015-01-01

    Purpose To evaluate the diagnostic yield of recommended chest computed tomography (CT) prompted by abnormalities detected on outpatient chest radiographic images. Materials and Methods This HIPAA-compliant study had institutional review board approval; informed consent was waived. Reports of all outpatient chest radiographic examinations performed at a large academic center during 2008 (n = 29 138) were queried to identify studies that included a recommendation for a chest CT imaging. The radiology information system was queried for these patients to determine if a chest CT examination was obtained within 1 year of the index radiographic examination that contained the recommendation. For chest CT examinations obtained within 1 year of the index chest radiographic examination and that met inclusion criteria, chest CT images were reviewed to determine if there was an abnormality that corresponded to the chest radiographic finding that prompted the recommendation. All corresponding abnormalities were categorized as clinically relevant or not clinically relevant, based on whether further work-up or treatment was warranted. Groups were compared by using t test and Fisher exact test with a Bonferroni correction applied for multiple comparisons. Results There were 4.5% (1316 of 29138 [95% confidence interval {CI}: 4.3%, 4.8%]) of outpatient chest radiographic examinations that contained a recommendation for chest CT examination, and increasing patient age (P < .001) and positive smoking history (P = .001) were associated with increased likelihood of a recommendation for chest CT examination. Of patients within this subset who met inclusion criteria, 65.4% (691 of 1057 [95% CI: 62.4%, 68.2%) underwent a chest CT examination within the year after the index chest radiographic examination. Clinically relevant corresponding abnormalities were present on chest CT images in 41.4% (286 of 691 [95% CI: 37.7%, 45.2%]) of cases, nonclinically relevant corresponding abnormalities in

  13. [Dedifferentiated Chondrosarcoma of the Chest Wall].

    PubMed

    Saitoh, Genkichi; Yoneshima, Yasuto; Nakamura, Toshihiko; Kitagawa, Dai; Kinjo, Nao; Ohgaki, Kippei; Maehara, Shinichiro; Teramoto, Seiichi; Adachi, Eisuke; Ikeda, Yoichi; Mine, Mari

    2016-08-01

    A 79-year-old man complaining of an anterior chest mass with pain had an abnormal shadow on chest X-ray. A mass, 7 cm in size, with destruction of the right 4th rib was found on chest computed tomography. A F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) corresponding to the lesion showed an abnormal accumulation of FDG with the standardized uptake value(SUV) max=16.19. A malignant tumor of the chest wall origin was suspected and the tumor was resected with the 3th, 4th, and 5th ribs. Histologically, the tumor was diagnosed as dedifferentiated chondrosarcoma. He died of local recurrence about 5 months after the operation. PMID:27476566

  14. Aspergillosis - chest x-ray (image)

    MedlinePlus

    ... usually occurs in immunocompromised individuals. Here, a chest x-ray shows that the fungus has invaded the lung ... are usually seen as black areas on an x-ray. The cloudiness on the left side of this ...

  15. Tuberculosis, advanced - chest x-rays (image)

    MedlinePlus

    ... tissue, and can cause tissue death. These chest x-rays show advanced pulmonary tuberculosis. There are multiple light ... location of cavities within these light areas. The x-ray on the left clearly shows that the opacities ...

  16. Mechanical Loading of Cartilage Explants with Compression and Sliding Motion Modulates Gene Expression of Lubricin and Catabolic Enzymes

    PubMed Central

    Marková, Michala; Torzilli, Peter A.; Gallo, Luigi M.

    2015-01-01

    Objective Translation of the contact zone in articulating joints is an important component of joint kinematics, yet rarely investigated in a biological context. This study was designed to investigate how sliding contact areas affect cartilage mechanobiology. We hypothesized that higher sliding speeds would lead to increased extracellular matrix mechanical stress and the expression of catabolic genes. Design A cylindrical Teflon indenter was used to apply 50 or 100 N normal forces at 10, 40, or 70 mm/s sliding speed. Mechanical parameters were correlated with gene expressions using a multiple linear regression model. Results In both loading groups there was no significant effect of sliding speed on any of the mechanical parameters (strain, stress, modulus, tangential force). However, an increase in vertical force (from 50 to 100 N) led to a significant increase in extracellular matrix strain and stress. For 100 N, significant correlations between gene expression and mechanical parameters were found for TIMP-3 (r2 = 0.89), ADAMTS-5 (r2 = 0.73), and lubricin (r2 = 0.73). Conclusions The sliding speeds applied do not have an effect on the mechanical response of the cartilage, this could be explained by a partial attainment of the “elastic limit” at and above a sliding speed of 10 mm/s. Nevertheless, we still found a relationship between sliding speed and gene expression when the tissue was loaded with 100 N normal force. Thus despite the absence of speed-dependent mechanical changes (strain, stress, modulus, tangential force), the sliding speed had an influence on gene expression. PMID:26175864

  17. Video Compression

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Optivision developed two PC-compatible boards and associated software under a Goddard Space Flight Center Small Business Innovation Research grant for NASA applications in areas such as telerobotics, telesciences and spaceborne experimentation. From this technology, the company used its own funds to develop commercial products, the OPTIVideo MPEG Encoder and Decoder, which are used for realtime video compression and decompression. They are used in commercial applications including interactive video databases and video transmission. The encoder converts video source material to a compressed digital form that can be stored or transmitted, and the decoder decompresses bit streams to provide high quality playback.

  18. [Differential diagnosis "non-cardiac chest pain"].

    PubMed

    Frieling, Thomas

    2015-07-01

    Non cardiac chest pain (NCCP) are recurrent angina pectoris like pain without evidence of coronary heart diesease in conventional diagnostic evaluation. The prevalence of NCCP is up to 70% and may be detected in this order at all levels of the medical health care system (general practitioner, emergency department, chest pain unit, coronary care). Reduction of quality of life in NCCP is comparable, partially even higher compared to cardiac chest pain. Reasons for psychological strain are symptom recurrence in app. 50%, nonspecific diagnosis with resulting uncertainty and insufficient integration of other medical disciplines in diagnostic work-up. Managing of patients with NCCP has to be interdisciplinary because non cardiac causes of chest pain may be found frequently. This are musculosceletal in app. 40%, gastrointestinal in app. 20%, psychiatric in app. 10% and pulmonary and mediastinal diseases in app. 5% of cases. Also gastroenterological expertise is required because here gastroesophageal reflux disease (GERD) in app. 60%, hypercontractile esophageal motility disorders with nutcracker, jackhammer esophagus or distal esophageal spasmus or achalasia in app. 20% and other esophageal alterations (e. g. infectious esophageal inflammation, drug-induced ulcer, rings, webs, eosinophilic esophagits) in app. 30% of cases may be detected as cause of chest pain may. This implicates that regular interdisciplinary round wards and interdisciplinary management of chest pain units are mandatory. PMID:26230070

  19. Tuberculous abscess on the chest wall.

    PubMed

    Aylk, S; Qakan, A; Aslankara, N; Ozsöz, A

    2009-03-01

    A 58-year old patient on dialysis for four years due to chronic renal failure presented with complaints of painless, continuously growing swelling on the left of his back and coughing, symptoms evolving over a period of approximately 3 months. Physical examination revealed a soft fixed mass of 10 x 10 x 4 cm on the left infrascapular area on the chest wall. The sample taken from the inflammation on the chest wall was analyzed with PCR method which resulted positive for Acid Fast Bacilli (AFB), tissue biopsy showed dermatitis with granulomata and sputum was positive for AFB. Thoracic MR, performed for the purpose of detecting the relationship between the lesion on the lung and the one on the chest wall, detected changes in the inflammatory soft tissues and multiple small abscess formations on the chest wall. There was no pathological signal in the bone structures of the chest wall. This case underlines the necessity to include "Empyema necessitatis" in the preliminary diagnosis when there is a soft tissue swelling on the chest wall without inflammatory signs in patients with reduced immune defences.

  20. Surgical stabilization of traumatic flail chest.

    PubMed Central

    París, F; Tarazona, V; Blasco, E; Cantó, A; Casillas, M; Pastor, J; París, M; Montero, R

    1975-01-01

    Since 1970 we have stabilized the ribs to correct paradoxical movement of the chest wall in chest injuries, using an original technique, in order to avoid as far as possible the need for long-term chest wall stabilization by intermittent positive pressure respiration (IPPR). The technical details of surgical stabilization are described, and the different types of stainless steel struts are shown. Type I was originally used either as an intramedullary nail or as an external brace. Types II and III were designed for external fixation of the strut to the rib. Treatment of 29 patients with severe flail chest, classified into four groups is shown: group I was treated by IPPR, group II by IPPR plus surgical stabilization, group III by surgical stabilization only, and group IV by surgical stabilization after exploratory thoracotomy. The clinical results are discussed. We conclude that surgical stabilization of the paradoxial movement of the chest wall can avoid the use of the respirator or at least reduce the interval of IPPR to a short period during the initial recovery from trauma. Using type III struts, we have obtained stabilization of the flail chest in all cases even in patients with severe anterior paradoxical movement. The patients' tolerance of surgical stainless steel struts was good. Images PMID:1105874

  1. Experimental Glaucoma Causes Optic Nerve Head Neural Rim Tissue Compression: A Potentially Important Mechanism of Axon Injury

    PubMed Central

    Fortune, Brad; Reynaud, Juan; Hardin, Christy; Wang, Lin; Sigal, Ian A.; Burgoyne, Claude F.

    2016-01-01

    Purpose We tested the hypothesis that experimental glaucoma (EG) results in greater thinning of the optic nerve head (ONH) neural rim tissue than the peripapillary retinal nerve fiber layer (RNFL) tissue. Methods Longitudinal spectral-domain optical coherence tomography (SDOCT) imaging of the ONH and peripapillary RNFL was performed every other week under manometric IOP control (10 mm Hg) in 51 nonhuman primates (NHP) during baseline and after induction of unilateral EG. The ONH parameter minimum rim area (MRA) was derived from 80 radial B-scans centered on the ONH; RNFL cross-sectional area (RNFLA) from a peripapillary circular B-scan with 12° diameter. Results In control eyes, MRA was 1.00 ± 0.19 mm2 at baseline and 1.00 ± 0.19 mm2 at the final session (P = 0.77), while RNFLA was 0.95 ± 0.09 and 0.95 ± 0.10 mm2, respectively (P = 0.96). In EG eyes, MRA decreased from 1.00 ± 0.19 mm2 at baseline to 0.63 ± 0.21 mm2 at the final session (P < 0.0001), while RNFLA decreased from 0.95 ± 0.09 to 0.74 ± 0.19 mm2, respectively (P < 0.0001). Thus, MRA decreased by 36.4 ± 20.6% in EG eyes, significantly more than the decrease in RNFLA (21.7 ± 19.4%, P < 0.0001). Other significant changes in EG eyes included increased Bruch's membrane opening (BMO) nonplanarity (P < 0.05), decreased BMO aspect ratio (P < 0.0001), and decreased MRA angle (P < 0.001). Bruch's membrane opening area did not change from baseline in either control or EG eyes (P = 0.27, P = 0.15, respectively). Conclusions Optic nerve head neural rim tissue thinning exceeded peripapillary RNFL thinning in NHP EG. These results support the hypothesis that axon bundles are compressed transversely within the ONH rim along with glaucomatous deformation of connective tissues. PMID:27564522

  2. Compression, distortion and dislodgement of large caliber stents in congenital heart defects caused by cardiopulmonary resuscitation: a case series and review of the literature.

    PubMed

    Haas, Nikolaus A; Happel, Christoph M; Jategaonkar, Smita; Moysich, Axel; Hanslik, Andreas; Kececioglu, Deniz; Sandica, Eugen; Laser, Kai Thorsten

    2014-09-01

    Stenting of vascular, extracardiac or lately intracardiac stenosis has become an established interventional treatment for a variety of problems in congenital or acquired heart disease. Most stent procedures are completed successfully and the long-term outcome is favorable in the majority of cases. Stent collapse or deformation is a well recognized entity in peripheral stents and can be attributed to insufficient radial force; it can also be attributed to excessive external forces, like deformation of stents in the right ventricular outflow tract, where external compression is combined with continuous movement caused by the beating heart. The protection of the thoracic cage may prove to be insufficient in extraordinary circumstances, such as chest compression in trauma or cardiopulmonary resuscitation (CPR). In this case series, we describe three patients in whom large endovascular stents were placed to treat significant stenosis of the aorta, the aortic arch or the venous system of the inferior vena cava close to the atrium. In all patients, CPR was necessary during their clinical course for various reasons; after adequate CPR, including appropriate chest compression all patients survived the initial resuscitation phase. Clinical, echocardiographic as well as radiologic re-evaluation after resuscitation revealed significant stent distortion, compression, displacement or additional vascular injury. The possibility of mechanical deformation of large endovascular stents needs to be considered and recognized when performing CPR; if CPR is successful, immediate re-evaluation of the implanted stents--if possible by biplane fluoroscopy--seems mandatory.

  3. External cardiac compression may be harmful in some scenarios of pulseless electrical activity.

    PubMed

    Hogan, T S

    2012-10-01

    Pulseless electrical activity occurs when organised or semi-organised electrical activity of the heart persists but the product of systemic vascular resistance and the increase in systemic arterial flow generated by the ejection of the left venticular stroke volume is not sufficient to produce a clinically detectable pulse. Pulseless electrical activity encompasses a very heterogeneous variety of severe circulatory shock states ranging in severity from pseudo-cardiac arrest to effective cardiac arrest. Outcomes of cardiopulmonary resuscitation for pulseless electrical activity are generally poor. Impairment of cardiac filling is the limiting factor to cardiac output in many scenarios of pulseless electrical activity, including extreme vasodilatory shock states. There is no evidence that external cardiac compression can increase cardiac output when impaired cardiac filling is the limiting factor to cardiac output. If impaired cardiac filling is the limiting factor to cardiac output and the heart is effectively ejecting all the blood returning to it, then external cardiac compression can only increase cardiac output if it increases venous return and cardiac filling. Repeated cardiac compression asynchronous with the patient's cardiac cycle and raised mean intrathoracic pressure due to chest compression can be expected to reduce rather than to increase cardiac filling and therefore to reduce rather than to increase cardiac output in such circumstances. The hypothesis is proposed that the performance of external cardiac compression will have zero or negative effect on cardiac output in pulseless electrical activity when impaired cardiac filling is the limiting factor to cardiac output. External cardiac compression may be both directly and indirectly harmful to significant sub-groups of patients with pulseless electrical activity. We have neither evidence nor theory to provide comfort that external cardiac compression is not harmful in many scenarios of pulseless

  4. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  5. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  6. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  7. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  8. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  9. Biomechanics of chiasmal compression: Sensitivity of the mechanical behaviors of nerve fibers to variations in material property and geometry

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofei; Neely, Andrew J.; McIlwaine, Gawn G.; Lueck, Christian J.

    2016-05-01

    The mechanism of bitemporal hemianopia is still unclear. Previous research suggested that the nerve fiber packing pattern may contribute to the selective damage of nasal (crossed) nerve fibers. Numerical models were built using finite element modeling to study the biomechanics of optic nerve fibers. The sensitivity of the mechanical behaviors of the nerve fibers to variations of five parameters in the nerve fiber model were investigated using design of experiments (DOE). Results show that the crossing angle is a very significant factor that affects a wide range of responses of the model. The strain difference between the crossed and the uncrossed nerve fibers may account for the phenomenon of bitemporal hemianopia. This work also highlights the need for more accurate material properties of the tissues in the model and an improved understanding of the microstructure of the optic chiasm.

  10. Mechanical properties of carboniferous rocks in the Upper Silesian Coal Basin under uniaxial and triaxial compression tests

    SciTech Connect

    Bukowska, M.

    2005-04-01

    Many years' studies of geological properties of rocks from the Upper Silesian Coal Basin have resulted in acquisition of a substantial data base of mechanical parameters of rocks over the total strain range. It is found that the post-peak rock properties are closely related with the peak strength and the pre-peak properties. The relationship between the uniaxial ultimate strength, elastic modulus, and drop modulus are determined.

  11. Development of an accurate molecular mechanics model for buckling behavior of multi-walled carbon nanotubes under axial compression.

    PubMed

    Safaei, B; Naseradinmousavi, P; Rahmani, A

    2016-04-01

    In the present paper, an analytical solution based on a molecular mechanics model is developed to evaluate the elastic critical axial buckling strain of chiral multi-walled carbon nanotubes (MWCNTs). To this end, the total potential energy of the system is calculated with the consideration of the both bond stretching and bond angular variations. Density functional theory (DFT) in the form of generalized gradient approximation (GGA) is implemented to evaluate force constants used in the molecular mechanics model. After that, based on the principle of molecular mechanics, explicit expressions are proposed to obtain elastic surface Young's modulus and Poisson's ratio of the single-walled carbon nanotubes corresponding to different types of chirality. Selected numerical results are presented to indicate the influence of the type of chirality, tube diameter, and number of tube walls in detailed. An excellent agreement is found between the present numerical results and those found in the literature which confirms the validity as well as the accuracy of the present closed-form solution. It is found that the value of critical axial buckling strain exhibit significant dependency on the type of chirality and number of tube walls.

  12. Initial clinical evaluation of stationary digital chest tomosynthesis

    NASA Astrophysics Data System (ADS)

    Hartman, Allison E.; Shan, Jing; Wu, Gongting; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping; Heath, Michael; Wang, Xiaohui; Foos, David

    2016-03-01

    Computed Tomography (CT) is the gold standard for image evaluation of lung disease, including lung cancer and cystic fibrosis. It provides detailed information of the lung anatomy and lesions, but at a relatively high cost and high dose of radiation. Chest radiography is a low dose imaging modality but it has low sensitivity. Digital chest tomosynthesis (DCT) is an imaging modality that produces 3D images by collecting x-ray projection images over a limited angle. DCT is less expensive than CT and requires about 1/10th the dose of radiation. Commercial DCT systems acquire the projection images by mechanically scanning an x-ray tube. The movement of the tube head limits acquisition speed. We recently demonstrated the feasibility of stationary digital chest tomosynthesis (s-DCT) using a carbon nanotube (CNT) x-ray source array in benchtop phantom studies. The stationary x-ray source allows for fast image acquisition. The objective of this study is to demonstrate the feasibility of s-DCT for patient imaging. We have successfully imaged 31 patients. Preliminary evaluation by board certified radiologists suggests good depiction of thoracic anatomy and pathology.

  13. The role of molecular motors in the mechanics of active gels and the effects of inertia, hydrodynamic interaction and compressibility in passive microrheology

    NASA Astrophysics Data System (ADS)

    Uribe, Andres Cordoba

    The mechanical properties of soft biological materials are essential to their physiological function and cannot easily be duplicated by synthetic materials. The study of the mechanical properties of biological materials has lead to the development of new rheological characterization techniques. In the technique called passive microbead rheology, the positional autocorrelation function of a micron-sized bead embedded in a viscoelastic fluid is used to infer the dynamic modulus of the fluid. Single particle microrheology is limited to fluids were the microstructure is much smaller than the size of the probe bead. To overcome this limitation in two-bead microrheology the cross-correlated thermal motion of pairs of tracer particles is used to determine the dynamic modulus. Here we present a time-domain data analysis methodology and generalized Brownian dynamics simulations to examine the effects of inertia, hydrodynamic interaction, compressibility and non-conservative forces in passive microrheology. A type of biological material that has proven specially challenging to characterize are active gels. They are formed by semiflexible polymer filaments driven by motor proteins that convert chemical energy from the hydrolysis of adenosine triphosphate (ATP) to mechanical work and motion. Active gels perform essential functions in living tissue. Here we introduce a single-chain mean-field model to describe the mechanical properties of active gels. We model the semiflexible filaments as bead-spring chains and the molecular motors are accounted for by using a mean-field approach. The level of description of the model includes the end-to-end length and attachment state of the filaments, and the motor-generated forces, as stochastic state variables which evolve according to a proposed differential Chapman-Kolmogorov equation. The model allows accounting for physics that are not available in models that have been postulated on coarser levels of description. Moreover it allows

  14. Experimental comparison of Pressure ratio in Alpha and Gamma Stirling cryocoolers with identical compression space volumes and driven simultaneously by a solitary novel compact mechanism

    NASA Astrophysics Data System (ADS)

    Sant, K. D.; Bapat, S. L.

    2015-12-01

    The cryocooler technology is advancing in different ways at a considerable pace to explore cooler applications in diversified field. Stirling cryocoolers are capable to satisfy the contemporary requirements of a low-capacity cooler. A compact mechanism that can drive Stirling cryocooler with larger stroke and thus enhance the cooler performance is the need of the hour. The increase in the stroke will lead to a higher volumetric efficiency. Hence, a cryocooler with larger stroke will experience higher mass flow rate of the working fluid, thereby increasing its ideal cooling capacity. The novel compact drive mechanism that fulfils this need is a promising option in this regards. It is capable of operating more than one cryocoolers of different Stirling configurations simultaneously. This arrangement makes it possible to compare different Stirling cryocoolers on the basis of pressure ratio obtained experimentally. The preliminary experimental results obtained in this regard are presented here. The initial experimentation is carried out on two Alpha Stirling units driven simultaneously by the novel compact mechanism. The pressure ratio obtained during the initial stages is 1.3538, which is enhanced to 1.417 by connecting the rear volumes of the compressor pistons to each other. The fact that annular leak across the expander pistons due to high pressure ratio affects the cryocooler performance, generates the need to separate the expansion space from bounce space. This introduces a Gamma configuration that is operated simultaneously with one of the existing Alpha units by same drive mechanism and having identical compression space volume. The results obtained for pressure ratio in both these units prove the concept that cooling capacity of Alpha configuration exceeds that of Gamma under similar operating conditions. This has been observed at 14 bar and 20 bar charge pressures during the preliminary experimentation. These results are presented in this paper. Thus, the

  15. Micro-scale measurement of the mechanical properties of compressed pharmaceutical powders. 1: The elasticity and fracture behavior of microcrystalline cellulose.

    PubMed

    Hancock, B C; Clas, S D; Christensen, K

    2000-11-19

    The feasibility of using very small compacts ( approximately 8.0 x 4.5 x 0.4 mm; approximately 20 mg) to determine the elasticity and fracture behavior of compressed pharmaceutical powders using the three-point beam-bending technique was evaluated. Compacts of microcrystalline cellulose with a range of porosities were tested using a thermomechanical analyzer and values for the Young's modulus and critical stress intensity factor at zero porosity (E(0) and K(IC0)) were determined by extrapolation. The value of E(0) measured at ambient relative humidity on un-notched beams was found to be in close agreement with that reported for much larger samples, and the value of K(IC0) for the small notched compacts was at the lower limit of the accepted range of values for microcrystalline cellulose. The fracture toughness (R) and total energy of fracture (U) for the notched specimens were also determined and used to estimate the apparent surface energies for crack initiation (gamma(i)) and for total fracture (gamma(f)). To further probe the utility of the micro-scale mechanical testing techniques, the effects of humidity on the various mechanical properties of the small microcrystalline compacts were examined and it was found that E(0), K(IC0), R(0), gamma(i0) and gamma(f0) each decreased as the surrounding humidity (and water content of the samples) increased.

  16. Compressed Genotyping

    PubMed Central

    Erlich, Yaniv; Gordon, Assaf; Brand, Michael; Hannon, Gregory J.; Mitra, Partha P.

    2011-01-01

    Over the past three decades we have steadily increased our knowledge on the genetic basis of many severe disorders. Nevertheless, there are still great challenges in applying this knowledge routinely in the clinic, mainly due to the relatively tedious and expensive process of genotyping. Since the genetic variations that underlie the disorders are relatively rare in the population, they can be thought of as a sparse signal. Using methods and ideas from compressed sensing and group testing, we have developed a cost-effective genotyping protocol to detect carriers for severe genetic disorders. In particular, we have adapted our scheme to a recently developed class of high throughput DNA sequencing technologies. The mathematical framework presented here has some important distinctions from the ’traditional’ compressed sensing and group testing frameworks in order to address biological and technical constraints of our setting. PMID:21451737

  17. Investigation of Esophageal Sensation and Biomechanical Properties in Functional Chest Pain

    PubMed Central

    Nasr, Issam; Attaluri, Ashok; Hashmi, Syed; Gregersen, Hans; Rao, Satish S.C.

    2010-01-01

    OBJECTIVES There is limited and conflicting data regarding the role of esophageal hypersensitivity in the pathogenesis of functional chest pain (FCP). We examined esophageal sensori-motor properties, mechanics and symptoms in subjects with FCP. METHODS Esophageal balloon distension test (EBDT) was performed using impedance planimetry in 189 (m/f = 57/132) consecutive subjects with noncardiac, non-reflux chest pain, and 36 (m/f = 16/20) healthy controls. The biomechanical and sensory properties of subjects with and without esophageal hypersensitivity were compared to controls. The frequency, intensity and duration of chest pain were assessed. RESULTS: 143 (75 %) subjects had esophageal hypersensitivity and 46 (25%) had normal sensitivity. Typical chest pain was reproduced in 105/143 (74%) subjects. Subjects with hypersensitivity demonstrated larger cross-sectional area (CSA) (p<0.001), decreased esophageal wall strain (p<0.001) and distensibility (p<0.001), and lower thresholds for perception (p<0.01), discomfort (p<0.01) and pain (p<0.01) compared to those without hypersensitivity or healthy controls. Chest pain scores (mean ± SD) for frequency, intensity and duration were 2.5 ± 0.3, 2.2 ± 0.2 and 2.2 ± 0.2 respectively, and were similar between the two patient groups. CONCLUSIONS 75% of subjects with FCP demonstrate esophageal hypersensitivity. Visceral hyperalgesia and sensori-motor dysfunction of the esophagus play a key role in the pathogenesis of chest pain. PMID:20067548

  18. A Murine Closed-chest Model of Myocardial Ischemia and Reperfusion

    PubMed Central

    Kim, Se-Chan; Boehm, Olaf; Meyer, Rainer; Hoeft, Andreas; Knüfermann, Pascal; Baumgarten, Georg

    2012-01-01

    Surgical trauma by thoracotomy in open-chest models of coronary ligation induces an immune response which modifies different mechanisms involved in ischemia and reperfusion. Immune response includes cytokine expression and release or secretion of endogenous ligands of innate immune receptors. Activation of innate immunity can potentially modulate infarct size. We have modified an existing murine closed-chest model using hanging weights which could be useful for studying myocardial pre- and postconditioning and the role of innate immunity in myocardial ischemia and reperfusion. This model allows animals to recover from surgical trauma before onset of myocardial ischemia. Volatile anesthetics have been intensely studied and their preconditioning effect for the ischemic heart is well known. However, this protective effect precludes its use in open chest models of coronary artery ligation. Thus, another advantage could be the use of the well controllable volatile anesthetics for instrumentation in a chronic closed-chest model, since their preconditioning effect lasts up to 72 hours. Chronic heart diseases with intermittent ischemia and multiple hit models are other possible applications of this model. For the chronic closed-chest model, intubated and ventilated mice undergo a lateral blunt thoracotomy via the 4th intercostal space. Following identification of the left anterior descending a ligature is passed underneath the vessel and both suture ends are threaded through an occluder. Then, both suture ends are passed through the chest wall, knotted to form a loop and left in the subcutaneous tissue. After chest closure and recovery for 5 days, mice are anesthetized again, chest skin is reopened and hanging weights are hooked up to the loop under ECG control. At the end of the ischemia/reperfusion protocol, hearts can be stained with TTC for infarct size assessment or undergo perfusion fixation to allow morphometric studies in addition to histology and

  19. Treatment of Morbidity with Atypical Chest Pain

    PubMed Central

    Cott, Arthur

    1987-01-01

    The appropriate management of atypical chest pain requires an integration of medical and behavioural treatments. Unnecessary medicalization can increase morbidity. A sensitivity to the behavioural factors contributing to symptoms and disability may reduce both. The purpose of this paper is to provide physicians with a cognitive-behavioural perspective of the nature of morbidity and disability associated with chronic chest discomfort; some strategies for detecting heretofore unsuspected disability associated with chronic chest pain and related discomfort in patients with organic findings (both cardiac and non-cardiac), as well those with no identifiable disease process or organic cause; and some simple behavioural and cognitive-behavioural therapeutic techniques for treating and preventing such problems. PMID:21263912

  20. Enhancement of chest radiographs using eigenimage processing

    NASA Astrophysics Data System (ADS)

    Bones, Philip J.; Butler, Anthony P. H.; Hurrell, Michael

    2006-08-01

    Frontal chest radiographs ("chest X-rays") are routinely used by medical personnel to assess patients for a wide range of suspected disorders. Often large numbers of images need to be analyzed. Furthermore, at times the images need to analyzed ("reported") when no radiological expert is available. A system which enhances the images in such a way that abnormalities are more obvious is likely to reduce the chance that an abnormality goes unnoticed. The authors previously reported the use of principal components analysis to derive a basis set of eigenimages from a training set made up of images from normal subjects. The work is here extended to investigate how best to emphasize the abnormalities in chest radiographs. Results are also reported for various forms of image normalizing transformations used in performing the eigenimage processing.

  1. Systemic Air Embolism Associated with Pleural Pigtail Chest Tube Insertion

    PubMed Central

    Alkhankan, Emad; Nusair, Ahmad; Mazagri, Rida

    2016-01-01

    Pleural pigtail catheter placement is associated with many complications including pneumothorax, hemorrhage, and chest pain. Air embolism is a known but rare complication of pleural pigtail catheter insertion and has a high risk of occurrence with positive pressure ventilation. In this case report, we present a 50-year-old male with bilateral pneumonia who developed a pneumothorax while on mechanical ventilation with continuous positive airway pressure mode. During the placement of the pleural pigtail catheter to correct the pneumothorax, the patient developed a sudden left sided body weakness and became unresponsive. An air embolism was identified in the right main cerebral artery, which was fatal. PMID:27630781

  2. Systemic Air Embolism Associated with Pleural Pigtail Chest Tube Insertion

    PubMed Central

    Alkhankan, Emad; Nusair, Ahmad; Mazagri, Rida

    2016-01-01

    Pleural pigtail catheter placement is associated with many complications including pneumothorax, hemorrhage, and chest pain. Air embolism is a known but rare complication of pleural pigtail catheter insertion and has a high risk of occurrence with positive pressure ventilation. In this case report, we present a 50-year-old male with bilateral pneumonia who developed a pneumothorax while on mechanical ventilation with continuous positive airway pressure mode. During the placement of the pleural pigtail catheter to correct the pneumothorax, the patient developed a sudden left sided body weakness and became unresponsive. An air embolism was identified in the right main cerebral artery, which was fatal.

  3. Systemic Air Embolism Associated with Pleural Pigtail Chest Tube Insertion.

    PubMed

    Alkhankan, Emad; Nusair, Ahmad; Mazagri, Rida; Al-Ourani, Mohammed

    2016-01-01

    Pleural pigtail catheter placement is associated with many complications including pneumothorax, hemorrhage, and chest pain. Air embolism is a known but rare complication of pleural pigtail catheter insertion and has a high risk of occurrence with positive pressure ventilation. In this case report, we present a 50-year-old male with bilateral pneumonia who developed a pneumothorax while on mechanical ventilation with continuous positive airway pressure mode. During the placement of the pleural pigtail catheter to correct the pneumothorax, the patient developed a sudden left sided body weakness and became unresponsive. An air embolism was identified in the right main cerebral artery, which was fatal. PMID:27630781

  4. Misdiagnosed Chest Pain: Spontaneous Esophageal Rupture

    PubMed Central

    Inci, Sinan; Gundogdu, Fuat; Gungor, Hasan; Arslan, Sakir; Turkyilmaz, Atila; Eroglu, Atila

    2013-01-01

    Chest pain is one of themost common complaints expressed by patients presenting to the emergency department, and any initial evaluation should always consider life-threatening causes. Esophageal rupture is a serious condition with a highmortality rate. If diagnosed, successful therapy depends on the size of the rupture and the time elapsed between rupture and diagnosis.We report on a 41-year-old woman who presented to the emergency department complaining of left-sided chest pain for two hours. PMID:27122690

  5. Derivation and Validation of Two Decision Instruments for Selective Chest CT in Blunt Trauma: A Multicenter Prospective Observational Study (NEXUS Chest CT)

    PubMed Central

    Rodriguez, Robert M.; Langdorf, Mark I.; Nishijima, Daniel; Baumann, Brigitte M.; Hendey, Gregory W.; Medak, Anthony J.; Raja, Ali S.; Allen, Isabel E.; Mower, William R.

    2015-01-01

    Background Unnecessary diagnostic imaging leads to higher costs, longer emergency department stays, and increased patient exposure to ionizing radiation. We sought to prospectively derive and validate two decision instruments (DIs) for selective chest computed tomography (CT) in adult blunt trauma patients. Methods and Findings From September 2011 to May 2014, we prospectively enrolled blunt trauma patients over 14 y of age presenting to eight US, urban level 1 trauma centers in this observational study. During the derivation phase, physicians recorded the presence or absence of 14 clinical criteria before viewing chest imaging results. We determined injury outcomes by CT radiology readings and categorized injuries as major or minor according to an expert-panel-derived clinical classification scheme. We then employed recursive partitioning to derive two DIs: Chest CT-All maximized sensitivity for all injuries, and Chest CT-Major maximized sensitivity for only major thoracic injuries (while increasing specificity). In the validation phase, we employed similar methodology to prospectively test the performance of both DIs. We enrolled 11,477 patients—6,002 patients in the derivation phase and 5,475 patients in the validation phase. The derived Chest CT-All DI consisted of (1) abnormal chest X-ray, (2) rapid deceleration mechanism, (3) distracting injury, (4) chest wall tenderness, (5) sternal tenderness, (6) thoracic spine tenderness, and (7) scapular tenderness. The Chest CT-Major DI had the same criteria without rapid deceleration mechanism. In the validation phase, Chest CT-All had a sensitivity of 99.2% (95% CI 95.4%–100%), a specificity of 20.8% (95% CI 19.2%–22.4%), and a negative predictive value (NPV) of 99.8% (95% CI 98.9%–100%) for major injury, and a sensitivity of 95.4% (95% CI 93.6%–96.9%), a specificity of 25.5% (95% CI 23.5%–27.5%), and a NPV of 93.9% (95% CI 91.5%–95.8%) for either major or minor injury. Chest CT-Major had a sensitivity

  6. Maintaining end-expiratory transpulmonary pressure prevents worsening of ventilator-induced lung injury caused by chest wall constriction in surfactant-depleted rats

    PubMed Central

    Loring, Stephen H.; Pecchiari, Matteo; Valle, Patrizia Della; Monaco, Ario; Gentile, Guendalina; D'Angelo, Edgardo

    2014-01-01

    Objective To see whether in acute lung injury (ALI) 1) compression of the lungs caused by thoracoabdominal constriction degrades lung function and worsens ventilator-induced lung injury (VILI), and 2) maintaining end-expiratory transpulmonary pressure (Pl) by increasing positive end-expiratory pressure (PEEP) reduces the deleterious effects of chest wall constriction. Design Experimental study in rats. Setting Physiology laboratory. Interventions ALI was induced in 3 groups of 9 rats by saline lavage. Nine animals immediately sacrificed served as control group. Group L had lavage only, group LC had the chest wall constricted with an elastic binder, and group LCP had the same chest constriction but with PEEP raised to maintain end-expiratory Pl. After lavage, all groups were ventilated with the same pattern for 1½ hr. Measurements and Main Results Pl, measured with an esophageal balloon-catheter, lung volume changes, arterial blood gasses and pH were assessed during mechanical ventilation (MV). Lung wet-to-dry ratio (W/D), albumin, TNF-α, IL-1β, IL-6, IL-10, and MIP-2 in serum and bronchoalveolar lavage fluid (BALF), and serum E-selectin and von Willebrand Factor (vWF) were measured at the end of MV. Lavage caused hypoxemia and acidemia, increased lung resistance and elastance, and decreased end-expiratory lung volume. With prolonged MV, lung mechanics, hypoxemia, and W/D were significantly worse in group LC. Pro-inflammatory cytokines except E-selectin were elevated in serum and BALF in all groups, with significantly greater levels of TNF-α, IL-1β, and IL-6 in group LC, which also exhibited significantly worse bronchiolar injury and greater heterogeneity of airspace expansion at a fixed Pl than other groups. Conclusions Chest wall constriction in ALI reduces lung volume, worsens hypoxemia, and increases pulmonary edema, mechanical abnormalities, pro-inflammatory mediator release, and histological signs of VILI. Maintaining end-expiratory Pl at preconstriction

  7. Chest wall reconstruction after resection using hernia repair piece.

    PubMed

    Wu, Yimin; Zhang, Guofei; Zhu, Zhouyu; Chai, Ying

    2016-06-01

    Reconstruction of chest wall tumor is very important link of chest wall tumor resection. Many implants have been reported to be used to reconstruct the chest wall, such as steelwire, titanium mesh and polypropylene mesh. It is really hard for clinicians to decide which implant is the best one to replace the chest wall. We herein report a 68-year-old man who had underwent a chest wall reconstruction with a hernia repair piece and a Dacron hernia repair piece. The patient has maintained an excellent cosmetic and functional outcome since surgery, which proves that the hernia piece still has its place in reconstruction of chest wall. PMID:27293859

  8. Chest wall reconstruction after resection using hernia repair piece

    PubMed Central

    Wu, Yimin; Zhang, Guofei; Zhu, Zhouyu

    2016-01-01

    Reconstruction of chest wall tumor is very important link of chest wall tumor resection. Many implants have been reported to be used to reconstruct the chest wall, such as steelwire, titanium mesh and polypropylene mesh. It is really hard for clinicians to decide which implant is the best one to replace the chest wall. We herein report a 68-year-old man who had underwent a chest wall reconstruction with a hernia repair piece and a Dacron hernia repair piece. The patient has maintained an excellent cosmetic and functional outcome since surgery, which proves that the hernia piece still has its place in reconstruction of chest wall. PMID:27293859

  9. Haemodynamic responses to exercise, ATP infusion and thigh compression in humans: insight into the role of muscle mechanisms on cardiovascular function.

    PubMed

    González-Alonso, José; Mortensen, Stefan P; Jeppesen, Tina D; Ali, Leena; Barker, Horace; Damsgaard, Rasmus; Secher, Niels H; Dawson, Ellen A; Dufour, Stéphane P

    2008-05-01

    The muscle pump and muscle vasodilatory mechanism are thought to play important roles in increasing and maintaining muscle perfusion and cardiac output ((.)Q) during exercise, but their actual contributions remain uncertain. To evaluate the role of the skeletal muscle pump and vasodilatation on cardiovascular function during exercise, we determined leg and systemic haemodynamic responses in healthy men during (1) incremental one-legged knee-extensor exercise, (2) step-wise femoral artery ATP infusion at rest, (3) passive exercise (n=10), (4)femoral vein or artery ATP infusion (n=6), and (5) cyclic thigh compressions at rest and during passive and voluntary exercise (n=7). Incremental exercise resulted in progressive increases in leg blood flow (DeltaLBF 7.4 +/- 0.7 l min(-1)), cardiac output (Delta (.)Q 8.7 +/- 0.7 l min(-1)), mean arterial pressure (DeltaMAP 51 +/- 5 mmHg), and leg and systemic oxygen delivery and (.)VO2 . Arterial ATP infusion resulted in similar increases in (.)Q , LBF, and systemic and leg oxygen delivery, but central venous pressure and muscle metabolism remained unchanged and MAP was reduced. In contrast,femoral vein ATP infusion did not alter LBF, (.)Q or MAP. Passive exercise also increased blood flow (DeltaLBF 0.7 +/- 0.1 l min(-1)), yet the increase in muscle and systemic perfusion, unrelated to elevations in aerobic metabolism, accounted only for approximately 5% of peak exercise hyperaemia.Likewise, thigh compressions alone or in combination with passive exercise increased blood flow (DeltaLBF 0.5-0.7 l min(-1)) without altering (.)Q, MAP or (.)VO2. These findings suggest that the skeletal muscle pump is not obligatory for sustaining venous return, central venous pressure,stroke volume and (.)Q or maintaining muscle blood flow during one-legged exercise in humans.Further, its contribution to muscle and systemic peak exercise hyperaemia appears to be minimal in comparison to the effects of muscle vasodilatation. PMID:18339690

  10. Redox Imbalance in the Peripheral Mechanism Underlying the Mirror-Image Neuropathic Pain Due to Chronic Compression of Dorsal Root Ganglion.

    PubMed

    Lv, H; Chen, H; Xu, J J; Jiang, Y S; Shen, Y J; Zhou, S Z; Xu, H; Xiong, Y C

    2016-05-01

    Reactive oxygen species (ROS) play a critical role in the pathogenesis of neuropathic pain, but few studies have examined the role of oxidative stress in the mirror-image neuropathic pain (MINP). The present study was to investigate the role of ROS in MINP caused by chronic compression of the dorsal root ganglion (DRG) (CCD) in a rat model. SD rats were randomly divided into sham group and CCD group. CCD was conducted to induce MINP. CCD rats were intraperitoneally injected with α-Phenyl-N-tert-butyl-nitrone (PBN) at 7 days after surgery. Paw withdrawal mechanical threshold (PWMT) was measured at -1, 1, 3, 5 and 7 days after surgery in sham group and CCD group, and at 8 time points after PBN injection. Rats were sacrificed at 3 and 7 days after surgery in sham group and CCD group and at 0.5 and 2 h after PBN injection, and the superoxide dismutase (SOD) and catalase activities, as well as hydrogen peroxide (H2O2) and malonaldehyde (MDA) contents were determined in the contralateral DRGs. Results showed bilateral PWMT reduced significantly in sham group and CCD group, but it returned to nearly normal level in sham group. MDA content, H2O2 content and SOD activity increased significantly, while catalase activity remained unchanged in CCD rats. PBN at 100 mg/kg significantly attenuated bilateral mechanical hyperalgesia accompanied by the improvement of oxidative stress in the contralateral DRGs. Our results demonstrate that ROS produced in the contralateral DRG are involved in the pathogenesis of CCD induced MINP, and ROS scavenger may be a promising drug for the therapy of MINP. PMID:26471165

  11. Factors affecting mortality of hospitalized chest trauma patients in United Arab Emirates

    PubMed Central

    2013-01-01

    Background Predictors of mortality of chest trauma vary globally. We aimed to define factors affecting mortality of hospitalized chest trauma patients in Al-Ain City, United Arab Emirates. Methods The data of Al-Ain Hospital Trauma Registry were prospectively collected over a period of three years. Patients with chest trauma who were admitted for more than 24 hours in Al-Ain Hospital or who died after arrival to the hospital were included in the study. Univariate analysis was used to compare patients who died and those who survived. Gender, age, nationality, mechanism of injury, systolic blood pressure and GCS on arrival, the need for ventilatory support, presence of head injury, AIS for the chest and head, presence of injuries outside the chest, and ISS were studied. Significant factors were then entered into a backward stepwise likelihood ratio logistic regression model. Results 474 patients having a median (range) age of 35 (1–90) years were studied. 90% were males and 18% were UAE citizens. The main mechanism of injury was road traffic collisions (66%) followed by falls (23.4%). Penetrating trauma occurred in 4 patients (0.8%). 88 patients (18.6%) were admitted to the ICU. The median (range) ISS was 5 (1–43). 173 patients (36.5%) had isolated chest injury. Overall mortality rate was 7.2%. Mortality was significantly increased by low GCS (p < 0.0001), high ISS (p = 0.025), and low systolic blood pressure on arrival (p = 0.027). Conclusion Chest trauma is associated with a significant mortality in Al-Ain City. This was significantly related to the severity of head injury, injury severity score, and hypotension on arrival. PMID:23547845

  12. 30 CFR 57.6133 - Powder chests.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd.... (b) Detonators shall be kept in chests separate from explosives or blasting agents, unless separated... Publication No. 22, (May 1993), “Recommendations for the Safe Transportation of Detonators in a Vehicle...

  13. 30 CFR 57.6133 - Powder chests.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd.... (b) Detonators shall be kept in chests separate from explosives or blasting agents, unless separated... Publication No. 22, (May 1993), “Recommendations for the Safe Transportation of Detonators in a Vehicle...

  14. 30 CFR 57.6133 - Powder chests.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd.... (b) Detonators shall be kept in chests separate from explosives or blasting agents, unless separated... Publication No. 22, (May 1993), “Recommendations for the Safe Transportation of Detonators in a Vehicle...

  15. Adenocarcinoma - chest x-ray (image)

    MedlinePlus

    This chest x-ray shows adenocarcinoma of the lung. There is a rounded light spot in the right upper lung (left side ... density. Diseases that may cause this type of x-ray result would be tuberculous or fungal granuloma, and ...

  16. Coccidioidomycosis - chest x-ray (image)

    MedlinePlus

    This chest x-ray shows the affects of a fungal infection, coccidioidomycosis. In the middle of the left lung (seen on the ... defined borders. Other diseases that may explain these x-ray findings include lung abscesses, chronic pulmonary tuberculosis, chronic ...

  17. [Optimal beam quality for chest digital radiography].

    PubMed

    Oda, Nobuhiro; Tabata, Yoshito; Nakano, Tsutomu

    2014-11-01

    To investigate the optimal beam quality for chest computed radiography (CR), we measured the radiographic contrast and evaluated the image quality of chest CR using various X-ray tube voltages. The contrast between lung and rib or heart increased on CR images obtained by lowering the tube voltage from 140 to 60 kV, but the degree of increase was less. Scattered radiation was reduced on CR images with a lower tube voltage. The Wiener spectrum of CR images with a low tube voltage showed a low value under identical conditions of amount of light stimulated emission. The quality of chest CR images obtained using a lower tube voltage (80 kV and 100 kV) was evaluated as being superior to those obtained with a higher tube voltage (120 kV and 140 kV). Considering the problem of tube loading and exposure in clinical applications, a tube voltage of 90 to 100 kV (0.1 mm copper filter backed by 0.5 mm aluminum) is recommended for chest CR. PMID:25410333

  18. [Functional Outcome after Chest Wall Stabilisation].

    PubMed

    Kyriss, T; Lenz, U; Friedel, G

    2016-09-01

    This overview reviews the current literature to compare the functional results after surgical and conservative treatment of patients with flail chest and multiple rib fractures. Regarding functional aspects, patients in the early phase after a thoracic trauma are those that benefit most from the stabilisation of the chest wall by internal fixation of the ribs. Patients recover faster from restrictive respiratory disorders, have less pain and return to the workplace earlier after an operation compared with those that receive conservative treatment. In the medium term, however, patients that are treated conservatively also achieve normal pulmonary function values and become free of pain. The period of convalescence after blunt thoracic trauma is generally underestimated. Future studies of the functional outcome after severe chest injuries should take this into account and the development of functional parameters should be monitored for at least 24 months. A prospective data collection of early and long-term surgical results in registries would be suitable to evaluate benefits and indications of chest wall stabilisation. PMID:27607891

  19. Algorithm of chest wall keloid treatment

    PubMed Central

    Long, Xiao; Zhang, Mingzi; Wang, Yang; Zhao, Ru; Wang, Youbin; Wang, Xiaojun

    2016-01-01

    Abstract Keloids are common in the Asian population. Multiple or huge keloids can appear on the chest wall because of its tendency to develop acne, sebaceous cyst, etc. It is difficult to find an ideal treatment for keloids in this area due to the limit of local soft tissues and higher recurrence rate. This study aims at establishing an individualized protocol that could be easily applied according to the size and number of chest wall keloids. A total of 445 patients received various methods (4 protocols) of treatment in our department from September 2006 to September 2012 according to the size and number of their chest wall keloids. All of the patients received adjuvant radiotherapy in our hospital. Patient and Observer Scar Assessment Scale (POSAS) was used to assess the treatment effect by both doctors and patients. With mean follow-up time of 13 months (range: 6–18 months), 362 patients participated in the assessment of POSAS with doctors. Both the doctors and the patients themselves used POSAS to evaluate the treatment effect. The recurrence rate was 0.83%. There was an obvious significant difference (P < 0.001) between the before-surgery score and the after-surgery score from both doctors and patients, indicating that both doctors and patients were satisfied with the treatment effect. Our preliminary clinical result indicates that good clinical results could be achieved by choosing the proper method in this algorithm for Chinese patients with chest wall keloids. This algorithm could play a guiding role for surgeons when dealing with chest wall keloid treatment. PMID:27583896

  20. Algorithm of chest wall keloid treatment.

    PubMed

    Long, Xiao; Zhang, Mingzi; Wang, Yang; Zhao, Ru; Wang, Youbin; Wang, Xiaojun

    2016-08-01

    Keloids are common in the Asian population. Multiple or huge keloids can appear on the chest wall because of its tendency to develop acne, sebaceous cyst, etc. It is difficult to find an ideal treatment for keloids in this area due to the limit of local soft tissues and higher recurrence rate. This study aims at establishing an individualized protocol that could be easily applied according to the size and number of chest wall keloids.A total of 445 patients received various methods (4 protocols) of treatment in our department from September 2006 to September 2012 according to the size and number of their chest wall keloids. All of the patients received adjuvant radiotherapy in our hospital. Patient and Observer Scar Assessment Scale (POSAS) was used to assess the treatment effect by both doctors and patients. With mean follow-up time of 13 months (range: 6-18 months), 362 patients participated in the assessment of POSAS with doctors.Both the doctors and the patients themselves used POSAS to evaluate the treatment effect. The recurrence rate was 0.83%. There was an obvious significant difference (P < 0.001) between the before-surgery score and the after-surgery score from both doctors and patients, indicating that both doctors and patients were satisfied with the treatment effect.Our preliminary clinical result indicates that good clinical results could be achieved by choosing the proper method in this algorithm for Chinese patients with chest wall keloids. This algorithm could play a guiding role for surgeons when dealing with chest wall keloid treatment. PMID:27583896

  1. [Chest Wall Reconstruction Using Titanium Plates Sandwiched Between Sheets after Resection of Chest Wall Chondrosarcoma].

    PubMed

    Endoh, Makoto; Oizumi, Hiroyuki; Kato, Hirohisa; Suzuki, Jun; Watarai, Hikaru; Hamada, Akira; Suzuki, Katsuyuki; Takahashi, Ai; Nakahashi, Kenta; Sugawara, Masato; Tsuchiya, Takashi; Sadahiro, Mitsuaki

    2016-07-01

    Extensive chest wall resection carries the risk of difficult reconstruction and surgical complications. We report our experience on chest wall reconstruction using titanium plates for a wide thoracic defect after tumor resection. A 74-year-old man was diagnosed with chondrosarcoma of the 6th rib on the right. He needed extensive chest wall resection because of skip lesions on 4th rib noted on operative inspection, leaving a defect measuring 33 × 20 cm. Reconstruction using 5 transverse titanium plates sandwiched between an expanded polytetrafluoroethylene patch and a polypropylene mesh sheet stabilized the chest wall. This reconstruction allowed successful separation from ventilatory support after operation. The postoperative course was uneventful, and he was discharged on postoperative day 20. The advantages of this form of reconstruction over conventional prostheses are rigidity, and stability and usability. PMID:27365062

  2. Coughing Wheezing Shortness of Breath Tightness in Chest

    MedlinePlus

    ... Current Issue Past Issues Coughing Wheezing Shortness of Breath Tightness in Chest Past Issues / Fall 2006 Table ... you cough a lot, wheeze, are short of breath or feel tightness in your chest, you might ...

  3. CNE article: pain after lung transplant: high-frequency chest wall oscillation vs chest physiotherapy.

    PubMed

    Esguerra-Gonzalez, Angeli; Ilagan-Honorio, Monina; Fraschilla, Stephanie; Kehoe, Priscilla; Lee, Ai Jin; Marcarian, Taline; Mayol-Ngo, Kristina; Miller, Pamela S; Onga, Jay; Rodman, Betty; Ross, David; Sommer, Susan; Takayanagi, Sumiko; Toyama, Joy; Villamor, Filma; Weigt, S Samuel; Gawlinski, Anna

    2013-03-01

    Background Chest physiotherapy and high-frequency chest wall oscillation (HFCWO) are routinely used after lung transplant to facilitate removal of secretions. To date, no studies have been done to investigate which therapy is more comfortable and preferred by lung transplant recipients. Patients who have less pain may mobilize secretions, heal, and recover faster. Objectives To compare effects of HFCWO versus chest physiotherapy on pain and preference in lung transplant recipients. Methods In a 2-group experimental, repeated-measures design, 45 lung transplant recipients (27 single lung, 18 bilateral) were randomized to chest physiotherapy (10 AM, 2 PM) followed by HFCWO (6 PM, 10 PM; group 1, n=22) or vice versa (group 2, n=23) on postoperative day 3. A verbal numeric rating scale was used to measure pain before and after treatment. At the end of the treatment sequence, a 4-item patient survey was administered to assess treatment preference, pain, and effectiveness. Data were analyzed with χ(2) and t tests and repeated-measures analysis of variance. Results A significant interaction was found between mean difference in pain scores from before to after treatment and treatment method; pain scores decreased more when HFCWO was done at 10 AM and 6 PM (P =.04). Bilateral transplant recipients showed a significant preference for HFCWO over chest physiotherapy (11 [85%] vs 2 [15%], P=.01). However, single lung recipients showed no significant difference in preference between the 2 treatments (11 [42%] vs 14 [54%]). Conclusions HFCWO seems to provide greater decreases in pain scores than does chest physiotherapy. Bilateral lung transplant recipients preferred HFCWO to chest physiotherapy. HFCWO may be an effective, feasible alternative to chest physiotherapy. (American Journal of Critical Care. 2013;22:115-125).

  4. 30 CFR 77.412 - Compressed air systems.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Compressed air systems. 77.412 Section 77.412... for Mechanical Equipment § 77.412 Compressed air systems. (a) Compressors and compressed-air receivers... involving the pressure system of compressors, receivers, or compressed-air-powered equipment shall not...

  5. 30 CFR 77.412 - Compressed air systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Compressed air systems. 77.412 Section 77.412... for Mechanical Equipment § 77.412 Compressed air systems. (a) Compressors and compressed-air receivers... involving the pressure system of compressors, receivers, or compressed-air-powered equipment shall not...

  6. 30 CFR 77.412 - Compressed air systems.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Compressed air systems. 77.412 Section 77.412... for Mechanical Equipment § 77.412 Compressed air systems. (a) Compressors and compressed-air receivers... involving the pressure system of compressors, receivers, or compressed-air-powered equipment shall not...

  7. 30 CFR 77.412 - Compressed air systems.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Compressed air systems. 77.412 Section 77.412... for Mechanical Equipment § 77.412 Compressed air systems. (a) Compressors and compressed-air receivers... involving the pressure system of compressors, receivers, or compressed-air-powered equipment shall not...

  8. 30 CFR 77.412 - Compressed air systems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compressed air systems. 77.412 Section 77.412... for Mechanical Equipment § 77.412 Compressed air systems. (a) Compressors and compressed-air receivers... involving the pressure system of compressors, receivers, or compressed-air-powered equipment shall not...

  9. Epipericardial fat necrosis as a cause of acute chest pain

    PubMed Central

    Bogale, Vivek; Hurst, David; dePrisco, Gregory

    2016-01-01

    Acute chest pain is one of the most common reasons for presentation to the emergency department. Although most etiologies of chest pain are easy to clinically ascertain with routine history, physical, and laboratory examinations, we present an important benign cause of acute chest pain that may mimic acute coronary syndrome.

  10. Epipericardial fat necrosis as a cause of acute chest pain

    PubMed Central

    Bogale, Vivek; Hurst, David; dePrisco, Gregory

    2016-01-01

    Acute chest pain is one of the most common reasons for presentation to the emergency department. Although most etiologies of chest pain are easy to clinically ascertain with routine history, physical, and laboratory examinations, we present an important benign cause of acute chest pain that may mimic acute coronary syndrome. PMID:27695190

  11. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 4 2012-04-01 2012-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification...-rays as described in Appendix A. (b) A chest X-ray to establish the existence of pneumoconiosis...

  12. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 4 2013-04-01 2013-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification...-rays as described in Appendix A. (b) A chest X-ray to establish the existence of pneumoconiosis...

  13. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 4 2014-04-01 2014-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification...-rays as described in Appendix A. (b) A chest X-ray to establish the existence of pneumoconiosis...

  14. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification...-rays as described in Appendix A. (b) A chest X-ray to establish the existence of pneumoconiosis...

  15. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification...-rays as described in Appendix A. (b) A chest X-ray to establish the existence of pneumoconiosis...

  16. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  17. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 3 2014-10-01 2014-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  18. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 3 2012-10-01 2012-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  19. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  20. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  1. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  2. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 3 2013-10-01 2013-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  3. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  4. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  5. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 3 2011-10-01 2011-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  6. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  7. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  8. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  9. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  10. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  11. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  12. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  13. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  14. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  15. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  16. Large hiatal hernia at chest radiography in a woman with cardiorespiratory symptoms.

    PubMed

    Torres, Daniele; Parrinello, Gaspare; Cardillo, Mauro; Pomilla, Marina; Trapanese, Caterina; Michele, Bellanca; Lupo, Umberto; Schimmenti, Caterina; Cuttitta, Francesco; Pietrantoni, Rossella; Vogiatzis, Danai; Licata, Giuseppe

    2012-11-01

    Hiatal hernia (HH) is a frequent entity. Rarely, it may exert a wide spectrum of clinical presentations mimicking acute cardiovascular events such as angina-like chest pain until manifestations of cardiac compression that can include postprandial syncope, exercise intolerance, respiratory function, recurrent acute heart failure, and hemodynamic collapse. A 69-year-old woman presented to the emergency department complaining of fatigue on exertion, cough, and episodes of restrosternal pain with less than 1 hour of duration. Her medical history only included some episodes of bronchitis and no history of hypertension. The 12-lead electrocardiogram demonstrated sinus rhythm with right bundle-branch block. Laboratory tests, including cardiac troponin I, were within normal reference values. Chest radiography showed no significant pulmonary alterations and revealed in mediastinum a huge abnormal shadow overlapping the right heart compatible with a gastric bubble.The gastroscopy confirmed a large HH. A 2-dimensional transthoracic echocardiogram, using all standard and modified apical and parasternal views, revealed an echolucent mass, compatible with HH, compressing the right atrium. Also, it showed an altered left ventricular relaxation and a mild increase of pulmonary artery pressure (35 mm Hg). Spirometry showed a mild obstruction of the small airways, whereas coronary angiography showed normal coronary arteries. We concluded that the patient's symptomatology was related to the compressive effects of the large hiatal ernia, a neglected cause of cardiorespiratory symptoms. The surgical repair of HH was indicated.

  17. Effects of dividing the transverse carpal ligament on the mechanical behavior of the carpal bones under axial compressive load: a finite element study.

    PubMed

    Guo, Xin; Fan, Yubo; Li, Zong-Ming

    2009-03-01

    Transecting the transverse carpal ligament (TCL) is a routine procedure to surgically treat carpal tunnel syndrome; yet, its mechanical consequences on carpal bones are unclear. In this study, our intent was to perform a computational analysis of carpal biomechanics resulting from TCL release. A three-dimensional finite element model of the wrist was constructed, which included all the carpal bones, the distal ulna and radius, the proximal metacarpals and the interosseous ligaments. Cartilage layers of each bone were modeled manually according to anatomic visualization software. The TCL was also modeled in three dimensions and added to the bone model. A 100-Newton axial load was applied to the upper section of the second and third metacarpals. The effects of dividing the TCL on the displacements of the carpal bones and the contact stress distribution in the midcarpal joints were studied using a finite element analysis method. When the TCL was divided, the axial compressive load resulted in the carpal bones deviating more radially. More specifically, the carpal bones on the radial side of the capitate and lunate (i.e. the trapezium, trapezoid, and scaphoid) moved further toward the radius, and the carpal bones on the ulnar side of the capitate and lunate (i.e. hamate, triquetrum, and pisiform) moved further toward the metacarpals. The contact stresses and contact locations in the midcarpal joints changed as a result of dividing the TCL. The changes in displacements of carpal bones and the contact stress distributions in the midcarpal joints due to TCL release may be implicated for some of the postoperative complications associated with carpal tunnel release.

  18. Nuss procedure for surgical stabilization of flail chest with horizontal sternal body fracture and multiple bilateral rib fractures.

    PubMed

    Lee, Sung Kwang; Kang, Do Kyun

    2016-06-01

    Flail chest is a life-threatening situation that paradoxical movement of the thoracic cage was caused by multiply fractured ribs in two different planes, or a sternal fracture, or a combination of the two. The methods to achieve stability of the chest wall are controversy between surgical fixation and mechanical ventilation. We report a case of a 33-year-old man who fell from a high place with fail chest due to multiple rib fractures bilaterally and horizontal sternal fracture. The conventional surgical stabilization using metal plates by access to the front of the sternum could not provide stability of the flail segment because the fracture surface was obliquely upward and there were multiple bilateral rib fractures adjacent the sternum. The Nuss procedure was performed for supporting the flail segment from the back. Flail chest was resolved immediately after the surgery. The patient was weaned from the mechanical ventilation on third postoperative day successfully and was ultimately discharged without any complications.

  19. Traumatic chest injury in children: A single thoracic surgeon's experience in two Nigerian tertiary hospitals

    PubMed Central

    Okonta, Kelechi Emmanuel

    2015-01-01

    Background: This study was to determine the extent and outcome of childhood chest injury in Nigeria, and to compare results with that of other literatures. Patients and Methods: A Prospective study of all children under 18 years of age with chest trauma in two tertiary hospitals in Southern Nigeria from January 2012 to December 2014 was reviewed. The aetiology, type, associated injury, mechanism, treatment and outcome were evaluated. The patients were followed up in the clinic. The data were analysed using SPSS version 20.0 with a significant P < 0.05. Results: Thirty-one patients (12.1%) under 18 years of age of 256 chest trauma patients were managed in the thoracic units. The mean age was 9.78 ± 6.77 years and 27 (87.1%) were male. The aetiology in 13 was from falls, 10 from automobile crashes, 3 from gunshots, 4 from stabbing and 1 from abuse. The highest peak of chest injury was on Saturday of the week and April of the year. The pleural collections are as follows: 15 (71.4%) was haemothorax, 4 (19.1%) pneumothorax, 2 (9.5%) haemopneumothorax and 18 patients had lung contusion in combination or alone with the pleural collections. Seven patients who presented >12-h versus 2 who presented <12-h and 6 of children between 0 and 9 years versus 3 at 10-18 years of age had empyema thoracis (P value not significant). One death was recorded. Conclusion: Chest trauma in children is still not common, and blunt chest injury from falls and automobile accidents are more common than penetrating chest injury. Treatment with tube thoracostomy is the major management modality with empyema thoracis as the most common complication. PMID:26612123

  20. Diagnostic usefulness of chest computed radiography--film versus cathode-ray tube images.

    PubMed

    Ishigaki, T; Sakuma, S; Endo, T; Ikeda, M

    1995-02-01

    Seventy-one plain chest images obtained by computed radiography (CR) with an imaging plate were interpreted on film and two kinds of cathode-ray tube (CRT) monitors installed separately at two facilities (1,024 x 1,536 pixels, 8 bits, and 1,024 x 1,280 pixels, 10 bits) by 20 radiologists and four chest internists. The clinical categories of these 71 cases included pulmonary nodules and interstitial abnormalities. Image reading sessions were held over a total of 4 days, ie, 2 days and then another 2 days, 3 weeks later. Twenty-four observers formed four groups with six members each. Two groups read either films or CRT images at one of the two facilities. In the second experiment, 26 of 71 images were compressed at 10:1, 19 of 71 were compressed at 20:1, and 26 were not compressed. Analyses of the areas under the receiver-operating characteristic curves showed no significant differences in detection of pulmonary abnormalities between film and CRT. In detecting interstitial pulmonary abnormalities, film was more sensitive than CRT monitor. There were no significant differences in observers' performances between the two different kinds of CRT workstation. Subjective evaluation of image quality showed that images irreversibly compressed to the ratios of 10:1 and 20:1 were inferior to original images. Although further considerations are needed with regard to spatial resolution requirements, image processing, and image compression, the utilization of CR CRT image as a substitute for CR film image will be possible.

  1. Compression-bending of multi-component semi-rigid columns in response to axial loads and conjugate reciprocal extension-prediction of mechanical behaviours and implications for structural design.

    PubMed

    Lau, Ernest W

    2013-01-01

    The mathematical modelling of column buckling or beam bending under an axial or transverse load is well established. However, the existent models generally assume a high degree of symmetry in the structure of the column and minor longitudinal and transverse displacements. The situation when the column is made of several components with different mechanical properties asymmetrically distributed in the transverse section, semi-rigid, and subjected to multiple axial loads with significant longitudinal and transverse displacements through compression and bending has not been well characterised. A more comprehensive theoretical model allowing for these possibilities and assuming a circular arc contour for the bend is developed, and used to establish the bending axes, balance between compression and bending, and equivalent stiffness of the column. In certain situations, such as with pull cable catheters commonly used for minimally invasive surgical procedures, the compression loads are applied via cables running through channels inside a semi-rigid column. The model predicts the mathematical relationships between the radius of curvature of the bend and the tension in and normal force exerted by such cables. Conjugate extension with reciprocal compression-bending is a special structural arrangement for a semi-rigid column such that extension of one segment is linked to compression-bending of another by inextensible cables running between them. Leads are cords containing insulated electrical conductor coil and cables between the heart muscle and cardiac implantable electronic devices. Leads can behave like pull cable catheters through differential component pulling, providing a possible mechanism for inside-out abrasion and conductor cable externalisation. Certain design features may predispose to this mode of structural failure. PMID:23127643

  2. Myocardial contusion following nonfatal blunt chest trauma

    SciTech Connect

    Kumar, S.A.; Puri, V.K.; Mittal, V.K.; Cortez, J.

    1983-04-01

    Currently available diagnostic techniques for myocardial contusion following blunt chest trauma were evaluated. We investigated 30 patients prospectively over a period of 1 year for the presence of myocardial contusion. Among the 30 patients, eight were found to have myocardial contusion on the basis of abnormal electrocardiograms, elevated creatine phosphokinase MB fraction (CPK-MB), and positive myocardial scan. Myocardial scan was positive in seven of eight patients (87.5%). CPK-MB fraction was elevated in four of eight patients (50%). Definitive electrocardiographic changes were seen in only two of eight patients (25%). It appears that myocardial scan using technetium pyrophosphate and CPK-MB fraction determinations are the most reliable aids in diagnosis of myocardial contusion following blunt chest trauma.

  3. Penetrating chest wounds: a 10-year review.

    PubMed

    Sett, S S; Busse, E; Boyd, T; Burgess, J

    1987-09-01

    From January 1975 to December 1984, 93 patients with penetrating chest wounds were admitted to three hospitals in Regina. Sixty-three percent of the wounds were caused by knives and 34% by firearms. Sixty-three patients were treated conservatively, 18 patients had thoracotomy and 12 others underwent laparotomy. Of the 18 patients, 16 had wounds between the nipples; 8 of the 16 had injuries to the heart or great vessels. Whereas the majority of penetrating wounds to the chest may be treated by observation or thoracostomy alone, a surgical approach is recommended when penetrating injuries are thought to have traversed the mediastinum, because of the high incidence of associated cardiac injuries. In doubtful cases the decision should favour early thoracotomy.

  4. Specific Radiological Findings of Traumatic Gastrointestinal Tract Injuries in Patients With Blunt Chest and Abdominal Trauma.

    PubMed

    Kokabi, Nima; Harmouche, Elie; Xing, Minzhi; Shuaib, Waqas; Mittal, Pardeep K; Wilson, Kenneth; Johnson, Jamlik-Omari; Nicolaou, Savvas; Khosa, Faisal

    2015-05-01

    Gastrointestinal hollow viscus injury after blunt chest and abdominal trauma is uncommon and complicates 0.6%-1.2% of all cases of trauma. Early recognition of such injuries significantly decreases morbidity and mortality. Since physical examination is not accurate in detecting such injuries, contrast-enhanced computed tomography has been the mainstay for diagnosis in many emergency departments. This pictorial essay aims to review the incidence, mechanisms, and signs of gastrointestinal hollow viscus injuries in the setting of blunt chest and abdominal trauma.

  5. Advances in chest drain management in thoracic disease.

    PubMed

    George, Robert S; Papagiannopoulos, Kostas

    2016-02-01

    An adequate chest drainage system aims to drain fluid and air and restore the negative pleural pressure facilitating lung expansion. In thoracic surgery the post-operative use of the conventional underwater seal chest drainage system fulfills these requirements, however they allow great variability amongst practices. In addition they do not offer accurate data and they are often inconvenient to both patients and hospital staff. This article aims to simplify the myths surrounding the management of chest drains following chest surgery, review current experience and explore the advantages of modern digital chest drain systems and address their disease-specific use. PMID:26941971

  6. Advances in chest drain management in thoracic disease.

    PubMed

    George, Robert S; Papagiannopoulos, Kostas

    2016-02-01

    An adequate chest drainage system aims to drain fluid and air and restore the negative pleural pressure facilitating lung expansion. In thoracic surgery the post-operative use of the conventional underwater seal chest drainage system fulfills these requirements, however they allow great variability amongst practices. In addition they do not offer accurate data and they are often inconvenient to both patients and hospital staff. This article aims to simplify the myths surrounding the management of chest drains following chest surgery, review current experience and explore the advantages of modern digital chest drain systems and address their disease-specific use.

  7. Advances in chest drain management in thoracic disease

    PubMed Central

    George, Robert S.

    2016-01-01

    An adequate chest drainage system aims to drain fluid and air and restore the negative pleural pressure facilitating lung expansion. In thoracic surgery the post-operative use of the conventional underwater seal chest drainage system fulfills these requirements, however they allow great variability amongst practices. In addition they do not offer accurate data and they are often inconvenient to both patients and hospital staff. This article aims to simplify the myths surrounding the management of chest drains following chest surgery, review current experience and explore the advantages of modern digital chest drain systems and address their disease-specific use. PMID:26941971

  8. Reconstruction of full thickness chest wall defects.

    PubMed Central

    Morgan, R F; Edgerton, M T; Wanebo, H J; Daniel, T M; Spotnitz, W D; Kron, I L

    1988-01-01

    Over the last 5 years, 14 patients were treated by wide en bloc resection of chest wall tumors with primary reconstruction. There were nine females and five male patients with an age range of 31-77 years. All patients had a skeletal resection of the chest wall. An average of 3.9 ribs were resected in the patients treated. In three patients a partial sternectomy was carried out in conjunction with the rib resections. Chest wall skeletal defects were reconstructed with Prolene mesh, which was placed under tension. Soft tissue reconstruction utilized selected portions of the latissimus dorsi musculocutaneous territory with fasciocutaneous extensions beyond the muscle itself. Primary healing was obtained in all patients and secondary procedures were not required. The average hospitalization was 23 days. All patients survived the resection and reconstruction and were alive 30 days after operation. In selected patients the preservation of a portion of the innervated muscle in situ or the transfer of the muscle with the preservation of its resting length has maintained the majority of the muscle function. Images Fig. 3A. Fig. 3C. Fig. 3D. Fig. 4A. Fig. 4C. Fig. 4D. Fig. 4E. Fig. 5A. Fig. 5B. Fig. 5D. Fig. 6A. Fig. 6C. Fig. 6D. Fig. 6E. Fig. 6F. Fig. 6G. Fig. 6H. PMID:3389939

  9. Chest pain associated with moderator band pacing.

    PubMed

    Goli, Anil K; Kaszala, Karoly; Osman, Mohammed N; Lucke, John; Carrillo, Roger

    2014-10-01

    A 65-year-old man was evaluated for chronic chest pain that had been present for 8 years after placement of a dual-chamber implantable cardioverter-defibrillator to treat inducible ventricular tachycardia. Previous coronary angiography had revealed nonobstructive coronary artery disease and a left ventricular ejection fraction of 0.45 to 0.50, consistent with mild idiopathic nonischemic cardiomyopathy. Evaluation with chest radiography and transthoracic echocardiography showed the implantable cardioverter-defibrillator lead to be embedded within the right ventricle at the moderator band, which had mild calcification. Treatment included extraction of the dual-coil lead and placement of a new single-coil right ventricular lead at the mid septum. The patient had complete relief of symptoms after the procedure. This case shows that chest pain can be associated with the placement of a right ventricular implantable cardioverter-defibrillator lead in the moderator band and that symptomatic relief can occur after percutaneous lead extraction and the implantation of a new right ventricular lead to the mid septal region.

  10. Surface Chest Motion Decomposition for Cardiovascular Monitoring

    NASA Astrophysics Data System (ADS)

    Shafiq, Ghufran; Veluvolu, Kalyana C.

    2014-05-01

    Surface chest motion can be easily monitored with a wide variety of sensors such as pressure belts, fiber Bragg gratings and inertial sensors, etc. The current applications of these sensors are mainly restricted to respiratory motion monitoring/analysis due to the technical challenges involved in separation of the cardiac motion from the dominant respiratory motion. The contribution of heart to the surface chest motion is relatively very small as compared to the respiratory motion. Further, the heart motion spectrally overlaps with the respiratory harmonics and their separation becomes even more challenging. In this paper, we approach this source separation problem with independent component analysis (ICA) framework. ICA with reference (ICA-R) yields only desired component with improved separation, but the method is highly sensitive to the reference generation. Several reference generation approaches are developed to solve the problem. Experimental validation of these proposed approaches is performed with chest displacement data and ECG obtained from healthy subjects under normal breathing and post-exercise conditions. The extracted component morphologically matches well with the collected ECG. Results show that the proposed methods perform better than conventional band pass filtering.

  11. Chest pain: coronary CT in the ER.

    PubMed

    Maffei, Erica; Seitun, Sara; Guaricci, Andrea I; Cademartiri, Filippo

    2016-01-01

    Cardiac CT has developed into a robust clinical tool during the past 15 years. Of the fields in which the potential of cardiac CT has raised more interest is chest pain in acute settings. In fact, the possibility to exclude with high reliability obstructive coronary artery disease (CAD) in patients at low-to-intermediate risk is of great interest both from the clinical standpoint and from the management standpoint. Several other modalities, with or without imaging, have been used during the past decades in the settings of new onset chest pain or in acute chest pain for both diagnostic and prognostic assessment of CAD. Each one has advantages and disadvantages. Most imaging modalities also focus on inducible ischaemia to guide referral to invasive coronary angiography. The advent of cardiac CT has introduced a new practice diagnostic paradigm, being the most accurate non-invasive method for identification and exclusion of CAD. Furthermore, the detection of subclinical CAD and plaque imaging offer the opportunity to improve risk stratification. Moreover, recent advances of the latest generation CT scanners allow combining both anatomical and functional imaging by stress myocardial perfusion. The role of cardiac CT in acute settings is already important and will become progressively more important in the coming years. PMID:26866681

  12. Surface Chest Motion Decomposition for Cardiovascular Monitoring

    PubMed Central

    Shafiq, Ghufran; Veluvolu, Kalyana C.

    2014-01-01

    Surface chest motion can be easily monitored with a wide variety of sensors such as pressure belts, fiber Bragg gratings and inertial sensors, etc. The current applications of these sensors are mainly restricted to respiratory motion monitoring/analysis due to the technical challenges involved in separation of the cardiac motion from the dominant respiratory motion. The contribution of heart to the surface chest motion is relatively very small as compared to the respiratory motion. Further, the heart motion spectrally overlaps with the respiratory harmonics and their separation becomes even more challenging. In this paper, we approach this source separation problem with independent component analysis (ICA) framework. ICA with reference (ICA-R) yields only desired component with improved separation, but the method is highly sensitive to the reference generation. Several reference generation approaches are developed to solve the problem. Experimental validation of these proposed approaches is performed with chest displacement data and ECG obtained from healthy subjects under normal breathing and post-exercise conditions. The extracted component morphologically matches well with the collected ECG. Results show that the proposed methods perform better than conventional band pass filtering. PMID:24865183

  13. Penetrating chest wound: a case report.

    PubMed

    Rourke, L L; McKenzie, F N; Heimbecker, R O

    1977-04-23

    An unusual penetrating chest injury was caused by a ball-point pen. Because of apparent penetration of the heart, preparations were made for an emergency open-heart procedure before emergency thoracotomy was undertaken, with the pen still in situ. The pen had bruised the epicardium but had not penetrated the pericardial sac. After removal of the pen, the wound was closed and a chest tube left in place. Recovery, apart from minor degrees of basal atelectasis, pleural effusion and wound infection, was uneventful. The outcome was consistent with that associated with current aggressive management of penetrating chest injuries. Management is based on three approaches. The primary one is intercostal thoracostomy tube drainage and fluid and blood replacement. In cases of massive hemorrhage or air leak, thoracotomy is necessary. The third approach is to prevent post-traumatic pulmonary insufficiency by using fine, high-efficiency filters during blood transfusion, avoiding excessive administration of intravenous fluids, performing tracheostomy after prolonged endotracheal intubation, and using a volume respirator with positive end-expiratory pressure. The average mortality for penetrating wounds of the heart is 25%.

  14. [New aspects of compression therapy].

    PubMed

    Partsch, Bernhard; Partsch, Hugo

    2016-06-01

    In this review article the mechanisms of action of compression therapy are summarized and a survey of materials is presented together with some practical advice how and when these different devices should be applied. Some new experimental findings regarding the optimal dosage (= compression pressure) concerning an improvement of venous hemodynamics and a reduction of oedema are discussed. It is shown, that stiff, non-yielding material applied with adequate pressure provides hemodynamically superior effects compared to elastic material and that relatively low pressures reduce oedema. Compression over the calf is more important to increase the calf pump function compared to graduated compression. In patients with mixed, arterial-venous ulcers and an ABPI over 0.6 inelastic bandages not exceeding a sub-bandage pressure of 40 mmHg may increase the arterial flow and improve venous pumping function. PMID:27259340

  15. Compression mechanism of subpicosecond pulses by malachite green dye in passively mode-locked rhodamine 6G/DODCI CW dye lasers

    SciTech Connect

    Watanabe, A.; Hara, M.; Kobayashi, H.; Takemura, H.; Tanaka, S.

    1983-04-01

    The pulse width compression effect of a malachite green (MG) dye upon subpicosecond pulses has been experimentally investigated in a CW passively mode-locked rhodamine 6G/DODCI dye laser. The pulse width reduces as MG concentration increases, and reaches 0.34 ps at 1.5 X 10/sup -6/ M. By adding the MG dye, good mode locking is achieved in a rather wide pumping-power range. A computer simulation of pulse growth has also been carried out by using simple rate equations, in which the fast-recovery component of loss due to the MG dye is taken into account. The simulated results can explain some experimental results qualitatively such as pulse width compression and pumping-power restriction. The pulse width compression results essentially from the fast recovery of cavity loss caused by the MG dye.

  16. Compression of multiwall microbubbles

    NASA Astrophysics Data System (ADS)

    Lebedeva, Natalia; Moore, Sam; Dobrynin, Andrey; Rubinstein, Michael; Sheiko, Sergei

    2012-02-01

    Optical monitoring of structural transformations and transport processes is prohibited if the objects to be studied are bulky and/or non-transparent. This paper is focused on the development of a microbbuble platform for acoustic imaging of heterogeneous media under harsh environmental conditions including high pressure (<500 atm), temperature (<100 C), and salinity (<10 wt%). We have studied the compression behavior of gas-filled microbubbles composed of multiple layers of surfactants and stabilizers. Upon hydrostatic compression, these bubbles undergo significant (up to 100x) changes in volume, which are completely reversible. Under repeated compression/expansion cycles, the pressure-volume P(V) characteristic of these microbubbles deviate from ideal-gas-law predictions. A theoretical model was developed to explain the observed deviations through contributions of shell elasticity and gas effusion. In addition, some of the microbubbles undergo peculiar buckling/smoothing transitions exhibiting intermittent formation of facetted structures, which suggest a solid-like nature of the pressurized shell. Preliminary studies illustrate that these pressure-resistant microbubbles maintain their mechanical stability and acoustic response at pressures greater than 1000 psi.

  17. [Ultra-low dose chest CT: The end of chest radiograph?].

    PubMed

    Ludes, Claire; Schaal, Marysa; Labani, Aissam; Jeung, Mi-Young; Roy, Catherine; Ohana, Mickaël

    2016-03-01

    Ultra-low dose chest CT (ULD-CT) is acquired at a radiation dose lowered to that of a PA and lateral chest X-ray. Its image quality is degraded, yet remains diagnostic in many clinical indications. Technological improvements, with iterative reconstruction at the foreground, allowed a strong increase in the image quality obtained with this examination, which is achievable on most recent (<5 years) scanner. Established clinical indications of ULD-CT are increasing, and its non-inferiority compared to the reference "full dose" chest CT are currently demonstrated for the detection of solid nodules, for asbestos-related pleural diseases screening and for the monitoring of infectious pneumonia. Its current limitations are the obese patients (BMI>35) and the interstitial pneumonia, situations in which their performances are insufficient. PMID:26830922

  18. Hyperbaric computed tomographic measurement of lung compression in seals and dolphins.

    PubMed

    Moore, Michael John; Hammar, Terrence; Arruda, Julie; Cramer, Scott; Dennison, Sophie; Montie, Eric; Fahlman, Andreas

    2011-07-15

    Lung compression of vertebrates as they dive poses anatomical and physiological challenges. There has been little direct observation of this. A harbor and a gray seal, a common dolphin and a harbor porpoise were each imaged post mortem under pressure using a radiolucent, fiberglass, water-filled pressure vessel rated to a depth equivalent of 170 m. The vessel was scanned using computed tomography (CT), and supported by a rail and counterweighted carriage magnetically linked to the CT table movement. As pressure increased, total buoyancy of the animals decreased and lung tissue CT attenuation increased, consistent with compression of air within the lower respiratory tract. Three-dimensional reconstructions of the external surface of the porpoise chest showed a marked contraction of the chest wall. Estimation of the volumes of different body compartments in the head and chest showed static values for all compartments except the lung, which showed a pressure-related compression. The depth of estimated lung compression ranged from 58 m in the gray seal with lungs inflated to 50% total lung capacity (TLC) to 133 m in the harbor porpoise with lungs at 100% TLC. These observations provide evidence for the possible behavior of gas within the chest of a live, diving mammal. The estimated depths of full compression of the lungs exceeds previous indirect estimates of the depth at which gas exchange ceases, and concurs with pulmonary shunt measurements. If these results are representative for living animals, they might suggest a potential for decompression sickness in diving mammals.

  19. Turbulence in Compressible Flows

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Lecture notes for the AGARD Fluid Dynamics Panel (FDP) Special Course on 'Turbulence in Compressible Flows' have been assembled in this report. The following topics were covered: Compressible Turbulent Boundary Layers, Compressible Turbulent Free Shear Layers, Turbulent Combustion, DNS/LES and RANS Simulations of Compressible Turbulent Flows, and Case Studies of Applications of Turbulence Models in Aerospace.

  20. Segmentation of ribs in digital chest radiographs

    NASA Astrophysics Data System (ADS)

    Cong, Lin; Guo, Wei; Li, Qiang

    2016-03-01

    Ribs and clavicles in posterior-anterior (PA) digital chest radiographs often overlap with lung abnormalities such as nodules, and cause missing of these abnormalities, it is therefore necessary to remove or reduce the ribs in chest radiographs. The purpose of this study was to develop a fully automated algorithm to segment ribs within lung area in digital radiography (DR) for removal of the ribs. The rib segmentation algorithm consists of three steps. Firstly, a radiograph was pre-processed for contrast adjustment and noise removal; second, generalized Hough transform was employed to localize the lower boundary of the ribs. In the third step, a novel bilateral dynamic programming algorithm was used to accurately segment the upper and lower boundaries of ribs simultaneously. The width of the ribs and the smoothness of the rib boundaries were incorporated in the cost function of the bilateral dynamic programming for obtaining consistent results for the upper and lower boundaries. Our database consisted of 93 DR images, including, respectively, 23 and 70 images acquired with a DR system from Shanghai United-Imaging Healthcare Co. and from GE Healthcare Co. The rib localization algorithm achieved a sensitivity of 98.2% with 0.1 false positives per image. The accuracy of the detected ribs was further evaluated subjectively in 3 levels: "1", good; "2", acceptable; "3", poor. The percentages of good, acceptable, and poor segmentation results were 91.1%, 7.2%, and 1.7%, respectively. Our algorithm can obtain good segmentation results for ribs in chest radiography and would be useful for rib reduction in our future study.

  1. Important considerations in chest wall reconstruction.

    PubMed

    Momeni, Arash; Kovach, Stephen J

    2016-06-01

    Chest wall reconstruction represents one of the most challenging tasks in plastic surgery. Over the past several decades, a more profound understanding of surgical anatomy and physiology along with tremendous advances in surgical technique have resulted in substantial improvements in postoperative outcomes. Conceptually, the reconstructive goals include dead space obliteration, restoration of skeletal stability with protection of intrathoracic structures, and stable soft tissue coverage. Ideally, these goals are achieved with minimal aesthetic deformity. J. Surg. Oncol. 2016;113:913-922. © 2016 Wiley Periodicals, Inc. PMID:26969557

  2. Recurrent aggressive fibromatosis of the chest wall.

    PubMed

    Foà, Riccardo; Rizzo, Stefania; Petrella, Francesco; De Maria, Federica; Bellomi, Massimo

    2014-01-01

    A 57-year-old woman with a previous history of aesthetic surgery for breast reduction presented with a subcutaneous mass in the right axilla. A CT scan showed a solid mass on the chest wall, and she underwent surgical resection with a diagnosis of aggressive fibromatosis. After a 10-month period of follow-up, a local recurrence occurred, and in accordance with the up-to-date approach, the recurrence has been treated with a conservative approach (medical treatments) with good control of the symptoms and downsizing of the lesion.

  3. [Isolated chest trauma in elderly patients].

    PubMed

    Yersin, Bertrand; Carron, Pierre-Nicolas; Pasquier, Mathieu; Zingg, Tobias

    2015-08-12

    In elderly patients, a blunt trauma of the chest is associated with a significant risk of complications and mortality. The number of ribs fractures (≥ 4), the presence of bilateral rib fractures, of a pulmonary contusion, of existent comorbidities or acute extra-thoracic traumatic lesions, and lastly the severity of thoracic pain, are indeed important risk factors of complications and mortality. Their presence may require hospitalization of the patient. When complications do occur, they are represented by alveolar hypoventilation, pulmonary atelectasia and broncho-pulmonary infections. When hospitalization is required, it may allow for the specific treatment of thoracic pain, including locoregional anesthesia techniques. PMID:26449103

  4. Pitfalls and variants in pediatric chest imaging.

    PubMed

    García Asensio, D; Fernández Martín, M

    2016-05-01

    Most pitfalls in the interpretation of pediatric chest imaging are closely related with the technique used and the characteristics of pediatric patients. To obtain a quality image that will enable the correct diagnosis, it is very important to use an appropriate technique. It is important to know how technical factors influence the image and to be aware of the possible artifacts that can result from poor patient cooperation. Moreover, radiologists need to be familiar with the normal anatomy in children, with the classic radiologic findings, and with the anatomic and developmental variants to avoid misinterpreting normal findings as pathological.

  5. Results of chest wall resection and reconstruction in 162 patients with benign and malignant chest wall disease

    PubMed Central

    Aghajanzadeh, Manoucheher; Alavy, Ali; Taskindost, Mehrdad; Pourrasouly, Zahra; Aghajanzadeh, Gilda; massahnia, Sara

    2010-01-01

    Background Chest wall resection is a complicated treatment modality with significant morbidity. The purpose of this study is to report our experience with chest wall resections and reconstructions. Methods The records of all patients undergoing chest wall resection and reconstruction were reviewed. Diagnostic procedures, surgical indications, the location and size of the chest wall defect, performance of lung resection, the type of prosthesis, and postoperative complications were recorded. Results From 1997 to 2008, 162 patients underwent chest wall resection.113 (70%) of patients were male. Age of patients was 14 to 69 years. The most common indications for surgery were primary chest wall tumors. The most common localized chest wall mass has been seen in the anterior chest wall. Sternal resection was required in 22 patients, Lung resection in 15 patients, Rigid prosthetic reconstruction has been used in 20 patients and nonrigid prolene mesh and Marlex mesh in 40 patients. Mean intensive care unit stay was 8 days. In-hospital mortality was 3.7 % (six patients). Conclusions Chest wall resection and reconstruction with Bone cement sandwich with mesh can be performed as a safe and effective surgical procedure for major chest wall defects and respiratory failure is lower in prosthetic reconstruction patients than previously reported (6). PMID:22263024

  6. Compression of the palmar cutaneous nerve by ganglions of the wrist.

    PubMed

    Gessini, L; Jandolo, B; Pietrangeli, A; Senese, A

    1983-01-01

    Two cases of compression of the palmar cutaneous nerve by ganglion of the wrist are presented. The anatomy of the region, compression factors, mechanism and clinical features are discussed. Timely surgical removal of compression is recommended.

  7. Recurrent Chest Pain, as a Presenting Sign of Ovarian Endometrioma

    PubMed Central

    Yildirim, Mehmet; Oztekin, Ozgur; Oztekin, Deniz

    2011-01-01

    Chest pain is a rare sign of thoracal endometriosis associated with endometrioma of the tubo-ovarian endometrioma. We report the case periodic episodes of chest pain concurrent with menstruation in a 35-year-old female, in which ovarian endometrioma was diagnosed and left-sided oophorectomy was performed. After surgery, patient underwent medical treatment which included a Gn-RH agonist and a combined oral contraceptive. In the follow-up period, there was no evidence of chest pain. PMID:22084779

  8. Sudden Viscous Dissipation of Compressing Turbulence

    DOE PAGES

    Davidovits, Seth; Fisch, Nathaniel J.

    2016-03-11

    Here we report compression of turbulent plasma can amplify the turbulent kinetic energy, if the compression is fast compared to the viscous dissipation time of the turbulent eddies. A sudden viscous dissipation mechanism is demonstrated, whereby this amplified turbulent kinetic energy is rapidly converted into thermal energy, suggesting a new paradigm for fast ignition inertial fusion.

  9. Effects of depth and chest volume on cardiac function during breath-hold diving.

    PubMed

    Marabotti, Claudio; Scalzini, Alessandro; Cialoni, Danilo; Passera, Mirko; Ripoli, Andrea; L'Abbate, Antonio; Bedini, Remo

    2009-07-01

    Cardiac response to breath-hold diving in human beings is primarily characterized by the reduction of both heart rate and stroke volume. By underwater Doppler-echocardiography we observed a "restrictive/constrictive" left ventricular filling pattern compatible with the idea of chest squeeze and heart compression during diving. We hypothesized that underwater re-expansion of the chest would release heart constriction and normalize cardiac function. To this aim, 10 healthy male subjects (age 34.2 +/- 10.4) were evaluated by Doppler-echocardiography during breath-hold immersion at a depth of 10 m, before and after a single maximal inspiration from a SCUBA device. During the same session, all subjects were also studied at surface (full-body immersion) and at 5-m depth in order to better characterize the relationship of echo-Doppler pattern with depth. In comparison to surface immersion, 5-m deep diving was sufficient to reduce cardiac output (P = 0.042) and increase transmitral E-peak velocity (P < 0.001). These changes remained unaltered at a 10-m depth. Chest expansion at 10 m decreased left ventricular end-systolic volume (P = 0.024) and increased left ventricular stroke volume (P = 0.024). In addition, it decreased transmitral E-peak velocity (P = 0.012) and increased deceleration time of E-peak (P = 0.021). In conclusion the diving response, already evident during shallow diving (5 m) did not progress during deeper dives (10 m). The rapid improvement in systolic and diastolic function observed after lung volume expansion is congruous with the idea of a constrictive effect on the heart exerted by chest squeeze.

  10. Cross-chest liposuction in gynaecomastia

    PubMed Central

    Murali, Biju; Vijayaraghavan, Sundeep; Kishore, P.; Iyer, Subramania; Jimmy, Mathew; Sharma, Mohit; Paul, George; Chavare, Sachin

    2011-01-01

    Background: Gynaecomastia is usually treated with liposuction or liposuction with excision of the glandular tissue. The type of surgery chosen depends on the grade of the condition. Objective: Because gynaecomastia is treated primarily as a cosmetic procedure, we aimed at reducing the invasiveness of the surgery. Materials and Methods: The technique complies with all recommended protocols for different grades of gynaecomastia. It uses liposuction, gland excision, or both, leaving only minimal post-operative scars. The use of cross-chest liposuction through incisions on the edge of the areola helps to get rid of all the fat under the areola without an additional scar as in the conventional method. Results: This is a short series of 20 patients, all with bilateral gynaecomastia (i.e., 40 breasts), belonging to Simon's Stage 1 and 2, studied over a period of 2 years. The average period of follow-up was 15 months. Post-operative complications were reported in only two cases, with none showing long-term complications or issues specifically due to the procedure. Conclusions : Cross-chest liposuction for gynaecomastia is a simple yet effective surgical tool in bilateral gynaecomastia treatment to decrease the post-operative scars. The use of techniques like incision line drain placement and post-drain removal suturing of wounds aid in decreasing the scar. PMID:21713166

  11. Solitary fibrous tumour of the chest wall.

    PubMed

    Mohtarrudin, N; Nor Hanipah, Z; Mohd Dusa, N

    2016-04-01

    Extrapleural solitary fibrous tumours (SFTs) are rare tumours characterized by patternless spindle cells with haemangiopericytoma-like vascular spaces. Previously the tumours have been classified as haemangiopericytoma, an entity that is now considered obsolete. We report a case of extrapleural SFT arising in the soft tissue of the chest wall. The patient was a 31-year-old Malay lady presenting with a mobile swelling of the right chest wall for more than five years. During excision the tumour was noted to be well-circumscribed and yellowish in colour, giving an impression of lipoma. Microscopically, the tumour had patternless architecture, characterized by hypocellular and hypercellular areas. It was composed of uniform, spindle-shaped cells displaying oval nuclei, inconspicuous nucleoli, pale cytoplasm and indistinct cell borders. The mitotic count was 2 per 10 HPF. Branching, medium-sized thin-walled blood vessels in a haemangiopericytomatous growth pattern, some with hyalinised wall were identified. The neoplastic cells were immunoreactive to CD99 and CD34 and were non-immunoreactive to Desmin, Smooth Muscle Actin, S100 protein and EMA. We elucidate the challenges in diagnosing this tumour in this unusual location.

  12. Solitary fibrous tumour of the chest wall.

    PubMed

    Mohtarrudin, N; Nor Hanipah, Z; Mohd Dusa, N

    2016-04-01

    Extrapleural solitary fibrous tumours (SFTs) are rare tumours characterized by patternless spindle cells with haemangiopericytoma-like vascular spaces. Previously the tumours have been classified as haemangiopericytoma, an entity that is now considered obsolete. We report a case of extrapleural SFT arising in the soft tissue of the chest wall. The patient was a 31-year-old Malay lady presenting with a mobile swelling of the right chest wall for more than five years. During excision the tumour was noted to be well-circumscribed and yellowish in colour, giving an impression of lipoma. Microscopically, the tumour had patternless architecture, characterized by hypocellular and hypercellular areas. It was composed of uniform, spindle-shaped cells displaying oval nuclei, inconspicuous nucleoli, pale cytoplasm and indistinct cell borders. The mitotic count was 2 per 10 HPF. Branching, medium-sized thin-walled blood vessels in a haemangiopericytomatous growth pattern, some with hyalinised wall were identified. The neoplastic cells were immunoreactive to CD99 and CD34 and were non-immunoreactive to Desmin, Smooth Muscle Actin, S100 protein and EMA. We elucidate the challenges in diagnosing this tumour in this unusual location. PMID:27126667

  13. Acute chest pain emergencies - spouses' prehospital experiences.

    PubMed

    Forslund, Kerstin; Quell, Robin; Sørlie, Venke

    2008-10-01

    The call to the Emergency Medical Dispatch Centre is often a person's first contact with the health-care system in cases of acute illness or injury and acute chest pain is a common reason for calling. The aim was to illuminate how spouses to persons with acute chest pain experienced the alarm situation, the emergency call and the prehospital emergency care. Interviews were conducted with nineteen spouses. A phenomenological-hermeneutic approach was used for the analyses. The themes responsibility and uneasiness emerged as well as an overall theme of aloneness. Being a spouse to a person in need of acute medical and nursing assistance was interpreted as "Being responsible and trying to preserve life" and "Being able to manage the uneasiness and having trust in an uncertain situation." When their partners' life was at risk the spouses were in an escalating spiral of worry, uncertainty, stress, fear of loss, feeling of loneliness and desperation. They had to manage emotional distress and felt compelled to act to preserve life, a challenging situation. PMID:18929341

  14. [Management of the patient presenting chest pain].

    PubMed

    Nishio, Susumu; Yamada, Hirotsugu

    2011-12-01

    A variety of diseases cause chest pain. Some entities such as acute coronary syndrome, aortic dissection, and pulmonary embolism are Life-threatening and immediate medical interventions may be required. Acute coronary syndrome is a disease due to disruption of plaque in coronary arteries. The echocardiography can be utilized to diagnose these situation by detecting wall motion abnormalities. Aortic dissection occurs when a tear in the inner wall of the aorta causes blood to flow between the layers of the wall and force the layers apart. The diagnosis can be made by pointing out the intimal flap by echocardiographic examination. A pulmonary embolism is a sudden blockage in a lung artery, which usually caused by a blood clot in a deep vein thrombosis. The echocardiography can prove the existence of pulmonary hypertension and right ventricular over loading. When one performs echocardiography in patients with chest pain in the emergency room, it is important to observe patient's condition, physical findings, and the electrocardiogram. The life-threatening diseases such as acute coronary syndrome, aortic dissection and pulmonary embolism should be considered in the first. If these lethal diseases are ruled out, every possibility including diseases other than cardiovascular disease must be considered. In the emergency echocardiography, incomplete knowledge and skills may lead misdiagnosis and patient's life is threatened. Thus, expert sonographer should perform the examination. The most important issue is to save the patients not to complete the echocardiographic study in this situation.

  15. Optical compensation device for chest film radiography

    NASA Astrophysics Data System (ADS)

    Gould, Robert G.; Hasegawa, Bruce H.; DeForest, Sherman E.; Schmidt, Gregory W.; Hier, Richard G.

    1990-07-01

    Although chest radiography is the most commonly performed radiographic examination and one of the most valuable and cost-effective studies in medicine it suffers from relatively high error rates in both missing pathology and false positive interpretations. Detectability of lung nodules and other structures in underpenetrated regions of the chest film can be improved by both exposure and optical compensation but current compensation systems require major capital cost or a significant change in normal clinical practice. A new optical compensation system called the " Intelligent X-Ray Illuminator" (IXI) automatically and virtually instantaneously generates a patient-specific optical unsharp mask that is projected directly on a radiograph. When a radiograph is placed on the IXI which looks much like a conventional viewbox it acquires a low-resolution electronic image of this film from which the film transmission is derived. The transmission information is inverted and blurred in an image processor to form an unsharp mask which is fed into a spatial light modulator (SLM) placed between a light source and the radiograph. The SLM tailors the viewbox luminance by decreasing illumination to underexposed (i. e. transmissive) areas of the radiograph presenting the observer with an optically unsharp-masked image. The IXI uses the original radiograph and will allow it to be viewed on demand with conventional (uniform illumination. Potentially the IXI could introduce the known beneficial aspects of optical unsharp masking into radiology at low capital

  16. Pulsed spheromak reactor with adiabatic compression

    SciTech Connect

    Fowler, T K

    1999-03-29

    Extrapolating from the Pulsed Spheromak reactor and the LINUS concept, we consider ignition achieved by injecting a conducting liquid into the flux conserver to compress a low temperature spheromak created by gun injection and ohmic heating. The required energy to achieve ignition and high gain by compression is comparable to that required for ohmic ignition and the timescale is similar so that the mechanical power to ignite by compression is comparable to the electrical power to ignite ohmically. Potential advantages and problems are discussed. Like the High Beta scenario achieved by rapid fueling of an ohmically ignited plasma, compression must occur on timescales faster than Taylor relaxation.

  17. Multidetector computer tomography: evaluation of blunt chest trauma in adults.

    PubMed

    Palas, João; Matos, António P; Mascarenhas, Vasco; Herédia, Vasco; Ramalho, Miguel

    2014-01-01

    Imaging plays an essential part of chest trauma care. By definition, the employed imaging technique in the emergency setting should reach the correct diagnosis as fast as possible. In severe chest blunt trauma, multidetector computer tomography (MDCT) has become part of the initial workup, mainly due to its high sensitivity and diagnostic accuracy of the technique for the detection and characterization of thoracic injuries and also due to its wide availability in tertiary care centers. The aim of this paper is to review and illustrate a spectrum of characteristic MDCT findings of blunt traumatic injuries of the chest including the lungs, mediastinum, pleural space, and chest wall. PMID:25295188

  18. Biometric estimation of chest wall thickness of females

    SciTech Connect

    Berger, C.D.; Lane, B.H.

    1985-09-01

    Optimal use of whole-body counting data to estimate pulmonary deposition of many of the actinides is dependent upon accurate measurement of the thickness of the chest wall because of severe attenuation of low-energy x rays and photons associated with the decay of these radionuclides. An algorithm for estimation of female chest wall thicknesses, verified by real-time ultrasonic measurements, has been derived based on the correlation of measured chest wall thickness and other common biometric quantities. Use of this algorithm will reduce the error generally associated with estimation of internal actinide deposition previously resulting from assuming an average chest wall thickness for all female subjects.

  19. Chest radiography in acute aortic syndrome: pearls and pitfalls.

    PubMed

    Chawla, Ashish; Rajendran, Surendran; Yung, Wai Heng; Babu, Suresh Balasubramanian; Peh, Wilfred C

    2016-08-01

    Acute aortic syndrome is a group of life-threatening diseases of the thoracic aorta that usually present to the emergency department. It includes aortic dissection, aortic intramural hematoma, and penetrating aortic ulcer. Rare aortic pathologies of aorto-esophageal fistula and mycotic aneurysm may also be included in this list. All these conditions require urgent treatment with complex clinical care and management. Most patients who present with chest pain are evaluated with a chest radiograph in the emergency department. It is important that maximum diagnostic information is extracted from the chest radiograph as certain signs on the chest radiograph are extremely useful in pointing towards the diagnosis of acute aortic syndrome.

  20. Multidetector Computer Tomography: Evaluation of Blunt Chest Trauma in Adults

    PubMed Central

    Matos, António P.; Mascarenhas, Vasco; Herédia, Vasco

    2014-01-01

    Imaging plays an essential part of chest trauma care. By definition, the employed imaging technique in the emergency setting should reach the correct diagnosis as fast as possible. In severe chest blunt trauma, multidetector computer tomography (MDCT) has become part of the initial workup, mainly due to its high sensitivity and diagnostic accuracy of the technique for the detection and characterization of thoracic injuries and also due to its wide availability in tertiary care centers. The aim of this paper is to review and illustrate a spectrum of characteristic MDCT findings of blunt traumatic injuries of the chest including the lungs, mediastinum, pleural space, and chest wall. PMID:25295188

  1. Multidetector computer tomography: evaluation of blunt chest trauma in adults.

    PubMed

    Palas, João; Matos, António P; Mascarenhas, Vasco; Herédia, Vasco; Ramalho, Miguel

    2014-01-01

    Imaging plays an essential part of chest trauma care. By definition, the employed imaging technique in the emergency setting should reach the correct diagnosis as fast as possible. In severe chest blunt trauma, multidetector computer tomography (MDCT) has become part of the initial workup, mainly due to its high sensitivity and diagnostic accuracy of the technique for the detection and characterization of thoracic injuries and also due to its wide availability in tertiary care centers. The aim of this paper is to review and illustrate a spectrum of characteristic MDCT findings of blunt traumatic injuries of the chest including the lungs, mediastinum, pleural space, and chest wall.

  2. Rabbit model of chest wall rigidity induced by fentanyl and the effects of apomorphine.

    PubMed

    Soares, João Henrique Neves; Brosnan, Robert J; Smith, Andrea; Mayhew, Philipp D

    2014-10-01

    A rabbit model for fentanyl-induced chest wall rigidity and the effect of apomorphine was evaluated. Eleven New Zealand adult rabbits were anesthetized and mechanically ventilated. An esophageal balloon catheter was used to estimate pleural pressure (P(pl)). Chest wall compliance (C(cw)) at baseline was calculated during pentobarbital anesthesia. A loading dose of 0.1 mg kg(-1) of fentanyl followed by infusion of 0.01 mg kg(-1) min(-1) was started in all animals, and C(cw) reassessed. In the rabbits that developed decreased C(cw), apomorphine 0.4 mg kg(-1) followed by a 0.004 mg kg(-1) min(-1) was administered and C(cw) was reassessed. C(cw) at baseline and after fentanyl and fentanyl+apomorphine were compared with one-way ANOVA followed by Bonferroni-Holm test (P<0.05). In 5 rabbits, C(cw) decreased significantly after fentanyl administration and apomorphine was able to restore C(cw) to baseline values. Rabbits can be used as a model for fentanyl-induced chest wall rigidity. Results from this study support central dopaminergic pathways as being at least partially responsible for the opioid-induced chest wall rigidity.

  3. Effect of shape and size of lung and chest wall on stresses in the lung

    NASA Technical Reports Server (NTRS)

    Vawter, D. L.; Matthews, F. L.; West, J. B.

    1975-01-01

    To understand better the effect of shape and size of lung and chest wall on the distribution of stresses, strains, and surface pressures, we analyzed a theoretical model using the technique of finite elements. First we investigated the effects of changing the chest wall shape during expansion, and second we studied lungs of a variety of inherent shapes and sizes. We found that, in general, the distributions of alveolar size, mechanical stresses, and surface pressures in the lungs were dominated by the weight of the lung and that changing the shape of the lung or chest wall had relatively little effect. Only at high states of expansion where the lung was very stiff did changing the shape of the chest wall cause substantial changes. Altering the inherent shape of the lung generally had little effect but the topographical differences in stresses and surface pressures were approximately proportional to lung height. The results are generally consistent with those found in the dog by Hoppin et al (1969).

  4. Compressive behavior of fine sand.

    SciTech Connect

    Martin, Bradley E.; Kabir, Md. E.; Song, Bo; Chen, Wayne

    2010-04-01

    The compressive mechanical response of fine sand is experimentally investigated. The strain rate, initial density, stress state, and moisture level are systematically varied. A Kolsky bar was modified to obtain uniaxial and triaxial compressive response at high strain rates. A controlled loading pulse allows the specimen to acquire stress equilibrium and constant strain-rates. The results show that the compressive response of the fine sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the moisture content, initial density and lateral confinement. Partially saturated sand is more compliant than dry sand. Similar trends were reported in the quasi-static regime for experiments conducted at comparable specimen conditions. The sand becomes stiffer as initial density and/or confinement pressure increases. The sand particle size become smaller after hydrostatic pressure and further smaller after dynamic axial loading.

  5. Using coupled micropillar compression and micro-Laue diffraction to investigate deformation mechanisms in a complex metallic alloy Al13Co4

    NASA Astrophysics Data System (ADS)

    Bhowmik, Ayan; Dolbnya, Igor P.; Britton, T. Ben; Jones, Nicholas G.; Sernicola, Giorgio; Walter, Claudia; Gille, Peter; Dye, David; Clegg, William J.; Giuliani, Finn

    2016-03-01

    In this study, we have used in-situ micro-Laue diffraction combined with micropillar compression of focused ion beam milled Al13Co4 complex metallic alloy to investigate the evolution of deformation in Al13Co4. Streaking of the Laue spots shows that the onset of plastic flow occurs at stresses as low as 0.8 GPa, although macroscopic yield only becomes apparent at 2 GPa. The measured misorientations, obtained from peak splitting, enable the geometrically necessary dislocation density to be estimated as 1.1 × 1013 m-2.

  6. Relevance of an incidental chest finding

    PubMed Central

    Cortés-Télles, Arturo; Mendoza, Daniel

    2012-01-01

    Solitary pulmonary nodule represents 0.2% of incidental findings in routine chest X-ray images. One of the main diagnoses includes lung cancer in which small-cell subtype has a poor survival rate. Recently, a new classification has been proposed including the very limited disease stage (VLD stage) or T1-T2N0M0 with better survival rate, specifically in those patients who are treated with surgery. However, current recommendations postulate that surgery remains controversial as a first-line treatment in this stage. We present the case of a 46-year-old female referred to our hospital with a preoperative diagnosis of a solitary pulmonary nodule. On initial approach, a biopsy revealed a small cell lung cancer. She received multimodal therapy with surgery, chemotherapy, and prophylactic cranial irradiation and is currently alive without recurrence on a 2-year follow-up. PMID:22345914

  7. An atypical cause of atypical chest pain.

    PubMed

    Zaheen, Ahmad; Siemieniuk, Reed A; Gudgeon, Patrick

    2014-09-01

    The present report describes a case involving a 57-year-old HIV-positive man who presented with acute retrosternal chest pain accompanied by 24 h of fever. Septic arthritis of the manubriosternal joint was diagnosed based on magnetic resonance imaging findings in addition to Staphylococcus aureus bacteremia. To the authors' knowledge, the present case is only the 12th reported case of manubriosternal septic arthritis, and the first in an HIV-positive patient. Early diagnosis and treatment can circumvent the need for surgical intervention. Based on the present case report and review of the literature, the authors summarize the epidemiology, appropriate imaging and suggestions for antibiotic therapy for this rare presentation.

  8. Pleural fluids associated with chest infection.

    PubMed

    Quadri, Amal; Thomson, Anne H

    2002-12-01

    Pleural effusions are commonly associated with pneumonias and a small number of these progress to empyema. An understanding of the physiology and pathophysiology of pleural fluid aids the clinician in the management of empyema. There remains much debate about the optimal treatment of empyema in children. Early recognition of the condition is important since delayed therapy may result in unnecessary morbidity. Conventional management with high dose parenteral antibiotics and chest tube drainage remains the mainstay of therapy. However, this treatment modality may fail if the pleural fluid becomes viscous and loculated and, therefore, a more aggressive approach is required. Intrapleural fibrinolytic therapy has been shown to decrease the length of hospital stay and may reduce the need for surgical intervention. The prognosis in children with parapneumonic empyema is excellent with the vast majority retaining normal lung function at long term follow-up.

  9. Tracheobronchial injury due to blunt chest trauma.

    PubMed

    Mahmodlou, Rahim; Sepehrvand, Nariman

    2015-01-01

    Tracheobronchial avulsion resulting from blunt trauma is a very rare and serious condition, mostly due to high-speed traffic crashes. In this article, we briefly report the case of an 18-year-old man who was injured in a car accident and because of massive persistent air leakage (despite appropriate chest tube drainage), deemed to have a deep tracheobronchial injury. Due to a rapid drop in the patient's O2 saturation, he underwent an anterolateral thoracotomy. Endotracheal intubation was performed under direct visualization. The right mainstem bronchus was disrupted from the carina with a 1.5-cm stump remaining on the carina, and the remainder was crushed to the origin of the right superior lobe bronchus. Hence, a right superior lobectomy was performed and the postoperative course was uneventful. PMID:26157657

  10. Problem based review: pleuritic chest pain.

    PubMed

    Lee, R W; Hodgson, L E; Jackson, M B; Adams, N

    2012-01-01

    Pleuritic pain, a sharp discomfort near the chest wall exacerbated by inspiration is associated with a number of pathologies. Pulmonary embolus and infection are two common causes but diagnosis can often be challenging, both for experienced physicians and trainees. The underlying anatomy and pathophysiology of such pain and the most common aetiologies are presented. Clinical symptoms and signs that may arise alongside pleuritic pain are then discussed, followed by an introduction to the diagnostic tools such as the Wells’ score and current guidelines that can help to select the most appropriate investigation(s). Management of pulmonary embolism and other common causes of pleuritic pain are also discussed and highlighted by a clinical vignette. PMID:22993751

  11. Chest tuberculosis: Radiological review and imaging recommendations

    PubMed Central

    Bhalla, Ashu Seith; Goyal, Ankur; Guleria, Randeep; Gupta, Arun Kumar

    2015-01-01

    Chest tuberculosis (CTB) is a widespread problem, especially in our country where it is one of the leading causes of mortality. The article reviews the imaging findings in CTB on various modalities. We also attempt to categorize the findings into those definitive for active TB, indeterminate for disease activity, and those indicating healed TB. Though various radiological modalities are widely used in evaluation of such patients, no imaging guidelines exist for the use of these modalities in diagnosis and follow-up. Consequently, imaging is not optimally utilized and patients are often unnecessarily subjected to repeated CT examinations, which is undesirable. Based on the available literature and our experience, we propose certain recommendations delineating the role of imaging in the diagnosis and follow-up of such patients. The authors recognize that this is an evolving field and there may be future revisions depending on emergence of new evidence. PMID:26288514

  12. Interpreting chest radiographs without visual search.

    PubMed

    Kundel, H L; Nodine, C F

    1975-09-01

    Ten radiologists were shown a series of 10 normal and 10 abnormal chest films under two viewing conditions: a 0.2-second flash and unlimited viewing time. The results were compared in terms of verbal content, diagnostic accuracy, and level of confidence. The overall accuracy was surprisingly high (70% true positives) considering that no search was possible. Performance improved as expected with free search (97% true positives). These data support the hypothesis that visual search begins with a global response that establishes content, detects gross deviations from normal, and organizes subsequent foveal checking fixations to conduct a detailed examination of ambiguities. The total search strategy then consists of an ordered sequence of interspersed global and checking fixations. PMID:125436

  13. Chest magnetic resonance imaging: a protocol suggestion*

    PubMed Central

    Hochhegger, Bruno; de Souza, Vinícius Valério Silveira; Marchiori, Edson; Irion, Klaus Loureiro; Souza Jr., Arthur Soares; Elias Junior, Jorge; Rodrigues, Rosana Souza; Barreto, Miriam Menna; Escuissato, Dante Luiz; Mançano, Alexandre Dias; Araujo Neto, César Augusto; Guimarães, Marcos Duarte; Nin, Carlos Schuler; Santos, Marcel Koenigkam; Silva, Jorge Luiz Pereira e

    2015-01-01

    In the recent years, with the development of ultrafast sequences, magnetic resonance imaging (MRI) has been established as a valuable diagnostic modality in body imaging. Because of improvements in speed and image quality, MRI is now ready for routine clinical use also in the study of pulmonary diseases. The main advantage of MRI of the lungs is its unique combination of morphological and functional assessment in a single imaging session. In this article, the authors review most technical aspects and suggest a protocol for performing chest MRI. The authors also describe the three major clinical indications for MRI of the lungs: staging of lung tumors; evaluation of pulmonary vascular diseases; and investigation of pulmonary abnormalities in patients who should not be exposed to radiation. PMID:26811555

  14. Use of chest sonography in acute-care radiology().

    PubMed

    De Luca, C; Valentino, M; Rimondi, M R; Branchini, M; Baleni, M Casadio; Barozzi, L

    2008-12-01

    Diagnosis of acute lung disease is a daily challenge for radiologists working in acute-care areas. It is generally based on the results of chest radiography performed under technically unfavorable conditions. Computed tomography (CT) is undoubtedly more accurate in these cases, but it cannot always be performed on critically ill patients who need continuous care.The use of thoracic ultrasonography (US) has recently been proposed for the study of acute lung disease. It can be carried out rapidly at the bedside and does not require any particularly sophisticated equipment. This report analyzes our experience with chest sonography as a supplement to chest radiography in an Emergency Radiology Unit. We performed chest sonography - as an adjunct to chest radiography - on 168 patients with acute chest pathology. Static and dynamic US signs were analyzed in light of radiographic findings and, when possible, CT. The use of chest US improved the authors' ability to provide confident diagnoses of acute disease of the chest and lungs.

  15. Sexual, Physical, Verbal/Emotional Abuse and Unexplained Chest Pain

    ERIC Educational Resources Information Center

    Eslick, Guy D.; Koloski, Natasha A.; Talley, Nicholas J.

    2011-01-01

    Objectives: Approximately one third of patients with non cardiac chest pain (NCCP) report a history of abuse, however no data exists on the prevalence of abuse among people with unexplained chest pain in the general population. We aimed to determine if there is a relationship between childhood sexual, physical, emotional abuse and unexplained…

  16. Management of chest drainage tubes after lung surgery.

    PubMed

    Satoh, Yukitoshi

    2016-06-01

    Since chest tubes have been routinely used to drain the pleural space, particularly after lung surgery, the management of chest tubes is considered to be essential for the thoracic surgeon. The pleural drainage system requires effective drainage, suction, and water-sealing. Another key point of chest tube management is that a water seal is considered to be superior to suction for most air leaks. Nowadays, the most common pleural drainage device attached to the chest tube is the three-bottle system. An electronic chest drainage system has been developed that is effective in standardizing the postoperative management of chest tubes. More liberal use of digital drainage devices in the postoperative management of the pleural space is warranted. The removal of chest tubes is a common procedure occurring almost daily in hospitals throughout the world. Extraction of the tube is usually done at the end of full inspiration or at the end of full expiration. The tube removal technique is not as important as how it is done and the preparation for the procedure. The management of chest tubes must be based on careful observation, the patient's characteristics, and the operative procedures that had been performed. PMID:27048219

  17. Myocardial perfusion imaging during chest pain: a useful clinical tool.

    PubMed

    Shehata, A R; LaSala, A F; Heller, G V

    1996-04-01

    A 72-year old man was injected with Tc 99m tetrofosmin during acute chest pain, in the presence of a nondiagnostic electrocardiogram (ECG). Myocardial perfusion imaging revealed a large anteroseptal defect. Subsequent catheterization confirmed left anterior descending artery disease. Acute imaging may be useful in the identification of critical disease in patients with chest pain and nondiagnostic ECG.

  18. Lung mass, right upper lung - chest x-ray (image)

    MedlinePlus

    This picture is a chest x-ray of a person with a lung mass. This is a front view, where the lungs are the two dark areas and ... visible in the middle of the chest. The x-ray shows a mass in the right upper lung, ...

  19. 46 CFR 194.10-20 - Magazine chest construction.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... lid shall have a minimum thickness of 1/8 inch. (b) Permanent sun shields shall be provided for sides... distance of 11/2 inches. Sun shields may be omitted when chests are installed “on deck protected,” shielded from direct exposure to the sun. (c) Chests shall be limited to a gross capacity of 100 cubic feet....

  20. 46 CFR 194.10-20 - Magazine chest construction.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... lid shall have a minimum thickness of 1/8 inch. (b) Permanent sun shields shall be provided for sides... distance of 11/2 inches. Sun shields may be omitted when chests are installed “on deck protected,” shielded from direct exposure to the sun. (c) Chests shall be limited to a gross capacity of 100 cubic feet....