High Energy Storage Density in Nanocomposites of P(VDF-TrFE-CFE) Terpolymer and BaZr0.2Ti0.8O3 Nanoparticles.

Polymer materials are actively used in dielectric capacitors, in particular for energy storage applications. An enhancement of the stored energy density can be achieved in composites of electroactive polymers and dielectric inorganic fillers with a high dielectric permittivity. In this article, we report on the energy storage characteristics of composites of relaxor terpolymer P(VDF-TrFE-CFE) and BaZr0.2Ti0.8O3 (BZT) nanoparticles. The choice of materials was dictated by their large dielectric permittivity in the vicinity of room temperature. Free-standing composite films, with BZT contents up to 5 vol.%, were prepared by solution casting. The dielectric properties of the composites were investigated over a wide range of frequencies and temperatures. It was shown that the addition of the BZT nanoparticles does not affect the relaxor behavior of the polymer matrix, but significantly increases the dielectric permittivity. The energy storage parameters were estimated from the analysis of the unipolar polarization hysteresis loops. The addition of the BZT filler resulted in the increasing discharge energy density. The best results were achieved for composites with 1.25-2.5 vol.% of BZT. In the range of electric fields to 150 MV/m, the obtained materials demonstrate a superior energy storage density compared to other P(VDF-TFE-CFE) based composites reported in the literature.

Effect of Composition on Polarization Hysteresis and Energy Storage Ability of P(VDF-TrFE-CFE) Relaxor Terpolymers.

The temperature dependence of the dielectric permittivity and polarization hysteresis loops of P(VDF-TrFE-CFE) polymer films with different compositions are studied. Among them, the three compositions, 51.3/48.7/6.2, 59.8/40.2/7.3, and 70/30/8.1, are characterized for the first time. Relaxor behavior is confirmed for all studied samples. Increasing the CFE content results in lowering the freezing temperature and stabilizes the ergodic relaxor state. The observed double hysteresis loops are related to the field-induced transition to a ferroelectric state. The critical field corresponding to this transition varies with the composition and temperature; it becomes larger for temperatures far from the freezing temperature. The energy storage performance is evaluated from the analysis of unipolar polarization hysteresis loops. P(VDF-TrFE-CFE) 59.8/40.2/7.3 shows the largest energy density of about 5 J·cm-3 (at the field of 200 MV·m-1) and a charge-discharge efficiency of 63%, which iscomparable with the best literature data for the neat terpolymers.

Major Surgical Trauma Impairs the Function of Natural Killer Cells but Does Not Affect Monocyte Cytokine Synthesis.

Major traumatic and surgical injury increase the risk for infectious complications due to immune dysregulation. Upon stimulation with interleukin (IL) 12 by monocyte/macrophages, natural killer (NK) cells release interferon (IFN) γ that supports the elimination of the pathogen. In the present study, we investigated the impact of invasive spine surgery on the relationship between monocytes and NK cells upon exposure to Staphylococcus aureus. Mononuclear cells and serum were isolated from peripheral blood of patients before and up to 8 d after surgery and stimulated with inactivated S. aureus bacteria. NK cell and monocyte function were determined by flow cytometry. NK cells continuously lost their ability to produce IFN-γ during the first week after surgery independently from monocyte-derived IL-12 secretion. IFN-γ synthesis was minimal on day 8 and was associated with decreased expression of the IL-12 receptor and activation of transcription factors required for IFNG gene transcription. Addition of recombinant IL-12 could at least partially restore NK cell function. Pre-operative levels of growth/differentiation factor (GDF) 15 in the serum correlated with the extent of NK cell suppression and with hospitalization. Thus, NK cell suppression after major surgery might represent a therapeutic target to improve the immune defense against opportunistic infections.

Effects of electrocautery plus cell saver on the blood levels of carbon monoxide in hip arthroplasty / 中国组织工程研究

BACKGROUND: In order to conserve blood and keep the operating field clean, cell saver is often used with electrocautery in hip arthroplasty. When applying the principle of thermal coagulation, electrocautery produces tissue self-burning with noxious gas byproducts, including carbon monoxide(CO). However the existing blood salvage systems do not have any reoxygenation or filtration function for CO.OBJECTIVE: To evaluate the effects of simultaneous use of electrocautery and a cell saver system on the blood levels of CO in patients undergoing hip arthroplasty.DESIGN: A comparative observation.SETTING: Department of Orthopedics, Duisburg-Essen University.PARTICIPANTS: From August 2002 to August 2003, patients undergoing hip arthroplasty including the use of electrocautery as well as intended use of a cell saver system were selected from the Department of Orthopedics, Duisburg-Essen University. Exclusive criteria: ① smoking history; ② history of anemia, hemoglobinopathy or coagulopathy; ③history of organ dysfunction, including lung, liver and kidney; ④ preoperative abnormal electrocardiogram (ECG), including cardiac ischemia and/or arrhythmia.Among all the enrolled patients, those who ultimately received the retransfusion of processed salvaged blood were counted as the observed group,whereas the others who did not receive any retransfusion for inadequate salvaged volume or possible contamination within salvaging were added as the control group, and no allogenic blood was transfused. All the patients agreed to participate in the study.METHODS: ① All the operations were performed under combined intravenous and inhalation general anesthesia. ② Electrocautery was used for coaluation during the incision of subcutaneous tissues, fascias, muscles as well as capsules. ③ A cell saver system (Haemonetics Cell Saver #5 System, manufactured by Haemonetics Corporation, U.S.A.) was applied during the operation. Salvaged blood were retransfused into the patients after the procedure of filtration and wash. ④ Blood CO-Oximetry: Blood CO levels were measured by carboxyhemoglobin (CO-Hb) concentration with a spectrophotometric blood gas analyzer (ABL 700 series, manufactured by Radiometer, Copenhagen, Denmark). In both groups, systemic blood samples were collected from a radial arterial catheter at 3 time points, including preoperatively, postoperatively and merely before the retransfusion of salvaged blood and at 6 hours postoperatively. In the observed group, additionally samples were collected instantly after skin incision from the aspirator connected to the cell saver reservoir, directly after femoral stem implantation also from the aspirator and immediately before retransfusion from the collecting sac, to reveal the trend of CO-Hb levels in salvaged blood.MAIN OUTCOMEMEASURES: CO-Hb levels in the systemic blood and salvaged blood at different time points were mainly observed.RESULTS: Totally 49 patients were involved in the analysis of results. ① General data: Forty-nine ASA Ⅰ -Ⅱ patients were enrolled in this study.There were 35 and 14 patients in the observed and control group, respectively, with 7 and 3 had a history of coronary heart diseases (heart function of class Ⅰ - Ⅱ ) correspondingly. There were no obvious differences in the sex, age, mean operative time and mean estimated blood loss between the two groups (P ＞ 0.05). The vital signs were stable in all the patients. ② CO-Hb concentration: In the observed group, the CO-Hb concentration in systemic blood at 6 hours postoperatively was significantly increased as compared with the preoperative and postoperative ones [(2.2±0.54)%,(1.6±0.34)%, (1.7±0.19)%, P ＜ 0.05]; the CO-Hb concentration in salvaged blood was (2.6±0.62)%, which was significantly higher than that in systemic blood preoperatively and postoperatively (P ＜ 0.01). In the control group, the CO-Hb concentration in systemic blood at 6 hours postoperatively had no obvious differences as compared with the preoperative and postoperative ones (P ＞ 0.05). ③ Postoperative conditions: In the observed group, sinus tachycardia and inferior myocardial ischemia were detected by ECG monitoring in 2 patients with pre-existing coronary heart disease,which complained of precardial discomfort at 4-6 hours postoperatively.Higher levels of CO-Hb were detected in salvaged blood before retransfusion (39% and 4.5%) and in systemic blood at 6 hours postoperatively(3.5% and 4.2%). No patient in the control group demonstrated symptoms of CO intoxication or cardiovascular compromise, also no abnormal changes were revealed by ECG monitoring.CONCLUSION: Retransfusion of salvaged blood in hip arthroplasty with simultaneous use of electrocautery and a cell saver system leads to a significant increase of systemic CO-Hb concentration, which can provoke the cardiovascular compromise. Therefore, it is suggested to measure CO-Hb level in salvaged blood, the retransfusion of which should be cautious, especially to patients with pre-existing heart diseases.

Efficacy and safety of a novel moldable, resorbable, and degradable sealant of bone surfaces for hemostasis after bone graft harvesting from the iliac crest.

STUDY DESIGN: A prospective, controlled, open, randomized multicenter study. OBJECTIVE: The study's objective was to demonstrate equivalence of a novel, moldable, resorbable, and degradable synthetic polymer (Bone Seal) compared with a collagen fleece (Lyostypt) in efficacy and safety for topical hemostasis after iliac crest bone graft harvesting. SUMMARY OF BACKGROUND DATA: Harvesting cortico-cancellous bone from the iliac crest is a well established procedure in orthopedic and particularly in spine surgery. It is associated with significant morbidity at the donor site where hematoma formation may cause impaired wound healing and infections in up to 10% of cases. METHODS: A total of 112 patients were included in the safety analysis. Safety was determined by a compound wound healing score and the incidence of adverse clinical effects. One hundred and eight patients were studied for equivalence in efficacy using a compound bleeding score. The handling properties and the application to the bone surface of either device were measured with two additional compound scores. RESULTS: The mean bleeding scores in the final analysis was 4.5 +/- 1.3 for the Bone Seal group and 4.2 +/- 1.3 for the collagen fleece group. Bone Seal was better applicable to the bleeding bone surfaces than the collagen fleece, even though its handling was more complicated. Wound healing and the incidences of adverse clinical events were comparable in either study group. CONCLUSIONS: Bone Seal is an effective and safe hemostatic material for sealing bleeding bone surfaces after iliac crest bone graft harvesting. By virtue of its hemostatic efficacy, Bone Seal is preventive for wound healing disorders.

Chylous leakage after thoracolumbar fracture may cause paraplegia.

STUDY DESIGN: Retrospective case report. PURPOSE: This case demonstrates that paraplegia can develop due to chylous leakage into the spinal canal without obvious retroperitoneal or intrathoracic involvement. BACKGROUND INFORMATION: This clinical presentation of chylous leakage has not been reported previously. RESULTS A 61-year-old female with osteoporosis suffered a pathologic fracture of the vertebral bodies T12 and L1 and developed partial paraplegia two weeks later. Imaging showed expansive pooling of intraspinal fluid without intrathoracic or retroperitoneal involvement. A blood-tinged fluid was aspirated from dorsal. Repeated surgery by a posterior approach with drainage of the fluid did not improve the patient's condition, so she was finally transferred to our hospital. Under the suspected diagnosis of lymphatic leakage a scintiscan with 123I-iodinephenylpentadekanacid-marked cream verified the presumption of a lymph fistula at the level of T12/L1, originating from the thoracic duct. By permanent draining of the posterior fistula without suction and strict intravenous alimentation the fluid production decreased continuously and finally ceased completely. Simultaneously, the neurologic state improved gradually without returning to normal completely. CONCLUSIONS: This case demonstrates that paraplegia can develop due to chylous leakage into the spinal canal without obvious retroperitoneal or intrathoracic involvement. This differential diagnosis should be kept in mind when treating patients with abundant fluid drainage into or from the spinal canal.

Resection arthroplasty of the sternoclavicular joint for the treatment of primary degenerative sternoclavicular arthritis.

We describe the mid-term clinical results of the surgical treatment of primary degenerative arthritis of the sternoclavicular joint in eight women. They had not responded to conservative treatment and underwent a limited resection arthroplasty. For pre- and postoperative clinical evaluation we used the Rockwood score for the sternoclavicular joint. Postoperatively, the Constant score was also determined. The mean follow-up was 31 months (10 to 82). The median Rockwood score increased from 6 to 12.5 points. The median postoperative Constant score was 87 (65 to 91). Four patients had an excellent, three a good, and one a poor result. All patients were pleased with the cosmetic result. Resection arthroplasty is an effective and safe treatment for chronic, symptomatic degenerative arthritis of the sternoclavicular joint with a high degree of patient satisfaction.