Correlation between composition, microstructure, and emission properties in Nd-doped Si-rich Si oxynitride films: investigation into the nature of the sensitizer.

Rare earth (RE) ions doped in Si-based materials, compatible with Si technology, are promising compounds with regards to optical communication and energy conversion. In this article, we show the emission properties of Nd-doped Si-rich Si oxynitride (Nd-SRSON) films, and their dependence on the dangling bond density and the nature of the sensitizer. These films were prepared by reactive magnetron sputtering and post-annealing. The film composition, microstructure, and emission properties were investigated as a function of deposition parameters and annealing temperatures. Both Fourier transform infrared (FTIR) and ellipsometry spectroscopy measurements have confirmed that the sample composition (Si/N ratio) can be carefully tuned by varying the ratio of reactive nitrogen to argon in the sputtering plasma. Moreover, FTIR and x-ray photoelectron spectroscopy measurements demonstrate the existence of both nitrogen and oxygen dangling bonds (N· and O·) in as-deposited samples. These dangling bonds were passivated during annealing. Under non-resonant excitation at 488 nm, the films exhibit a significant photoluminescence (PL) signal from Nd3+ ions demonstrating the occurrence of an effective sensitization of Nd3+ ions in the host matrix. Both PL excitation and ellipsometry results (the energy band gap from new amorphous model) exclude the sensitization by an exciton with energy over the band gap, whereas the presence of Si agglomerates, at the atomic scale, have been identified as effective sensitizers towards Nd3+ ions. This work not only provides knowledge to optimize Si-based materials for favorable emission properties, but also, presents a universal methodology to investigate the nature of sensitizers for RE emitters. This allows one to find correlations between composition, microstructure, and emission properties.

Structural and emission properties of Tb3+-doped nitrogen-rich silicon oxynitride films.

Terbium doped silicon oxynitride host matrix is suitable for various applications such as light emitters compatible with CMOS technology or frequency converter systems for photovoltaic cells. In this study, amorphous Tb3+ ion doped nitrogen-rich silicon oxynitride (NRSON) thin films were fabricated using a reactive magnetron co-sputtering method, with various N2 flows and annealing conditions, in order to study their structural and emission properties. Rutherford backscattering (RBS) measurements and refractive index values confirmed the silicon oxynitride nature of the films. An electron microscopy analysis conducted for different annealing temperatures (T A) was also performed up to 1200 °C. Transmission electron microscopy (TEM) images revealed two different sublayers. The top layer showed porosities coming from a degassing of oxygen during deposition and annealing, while in the region close to the substrate, a multilayer-like structure of SiO2 and Si3N4 phases appeared, involving a spinodal decomposition. Upon a 1200 °C annealing treatment, a significant density of Tb clusters was detected, indicating a higher thermal threshold of rare earth (RE) clusterization in comparison to the silicon oxide matrix. With an opposite variation of the N2 flow during the deposition, the nitrogen excess parameter (Nex) estimated by RBS measurements was introduced to investigate the Fourier transform infrared (FTIR) spectrum behavior and emission properties. Different vibration modes of the Si-N and Si-O bonds have been carefully identified from the FTIR spectra characterizing such host matrices, especially the 'out-of-phase' stretching vibration mode of the Si-O bond. The highest Tb3+ photoluminescence (PL) intensity was obtained by optimizing the N incorporation and the annealing conditions. In addition, according to these conditions, the integrated PL intensity variation confirmed that the silicon nitride-based host matrix had a higher thermal threshold of rare earth clusterization than its silicon oxide counterpart. Analysis of time-resolved PL intensity versus T A showed the impact of Tb clustering on decay times, in agreement with the TEM observations. Finally, PL and PL excitation (PLE) experiments and comparison of the related spectra between undoped and Tb-doped samples were carried out to investigate the impact of the band tails on the excitation mechanism of Tb3+ ions.

A critical role for NMDA receptors in parvalbumin interneurons for gamma rhythm induction and behavior.

Synchronous recruitment of fast-spiking (FS) parvalbumin (PV) interneurons generates gamma oscillations, rhythms that emerge during performance of cognitive tasks. Administration of N-methyl-D-aspartate (NMDA) receptor antagonists alters gamma rhythms, and can induce cognitive as well as psychosis-like symptoms in humans. The disruption of NMDA receptor (NMDAR) signaling specifically in FS PV interneurons is therefore hypothesized to give rise to neural network dysfunction that could underlie these symptoms. To address the connection between NMDAR activity, FS PV interneurons, gamma oscillations and behavior, we generated mice lacking NMDAR neurotransmission only in PV cells (PV-Cre/NR1f/f mice). Here, we show that mutant mice exhibit enhanced baseline cortical gamma rhythms, impaired gamma rhythm induction after optogenetic drive of PV interneurons and reduced sensitivity to the effects of NMDAR antagonists on gamma oscillations and stereotypies. Mutant mice show largely normal behaviors except for selective cognitive impairments, including deficits in habituation, working memory and associative learning. Our results provide evidence for the critical role of NMDAR in PV interneurons for expression of normal gamma rhythms and specific cognitive behaviors.

Thermal stability of high-k Si-rich HfO(2) layers grown by RF magnetron sputtering.

The microstructure and optical properties of HfSiO films fabricated by RF magnetron sputtering were studied by means of x-ray diffraction, transmission electron microscopy, spectroscopic ellipsometry and attenuated total reflection infrared spectroscopy versus annealing treatment. It was shown that silicon incorporation in the HfO(2) matrix plays an important role in the structure stability of the layers. Thus, the increase of the annealing temperature up to 1000 degrees C did not lead to the crystallization of the films. The evolution of the chemical composition as well as a decrease of the density of the films was attributed to the phase separation of HfSiO on HfO(2) and SiO(2) phases in the film. An annealing at 1000-1100 degrees C results in the formation of the multilayer Si-rich/Hf-rich structure and was explained by a surface-directed spinodal decomposition. The formation of the stable tetragonal structure of HfO(2) phase was shown upon annealing treatment at 1100 degrees C.

Malpractice claims and abdominal wall hernia repair.

PURPOSE: To present factual data on the medico-legal aspects of medicolegal claims after abdominal wall surgery in France. METHOD: Analysis of the complaints following parietal surgery that were addressed to a company that specializes in medical malpractice insurance between 2010 and 2016. RESULTS: Of 209 files, 180 were analyzable; these included 75 women and 105 men with a mean age of 51 years and a mean BMI of 29.8. Cases were mainly heard by the Conciliation and Compensation Commission (CCI) (82 patients) and the High Court (79 patients). The surgical procedures concerned were groin hernias (85 patients) or anterior abdominal wall hernias (95 patients). Conventional open surgery was performed in 123 patients and laparoscopic surgery in 57 patients. The incidents motivating patient complaints after groin hernia surgery were chronic pain (27 patients), infection (24 patients), testicular damage (10 patients). Seven patients died as a result of this surgery (including one fetus). Claims after ventral hernia repair were motivated by infections (46 patients) and post-operative peritonitis or bowel obstruction (12 patients). Nine patients died following these ventral hernia repairs. Surgical error was identified in 59 of the 168 cases analyzed (35.1%); 44% of recognized faults were surgical site infections, 27% linked to delay in re-operation, and 20% were related to the operating room environment. CONCLUSION: Hernia surgery, although an everyday event for many practitioners, requires the same rigor as all other visceral surgery.

Presence of anesthesiologists and nurses in the operating room: Liability of surgeons and health care facilities.

The presence of an anesthesiologist and certified registered nurse anesthesiologist in the operating room remains a topic of discussion in many facilities. This article provides an overview on the legislation and recommendations on this topic and recounts some of the related jurisprudence. The opinions of various actors, surgeons, anesthesiologists, anesthesiology-intensive care physicians, certified registered nurse anesthesiologists, care-facility directors and insurance companies are included. Based on these elements, we attempt to answer the question of presence of competence in anesthesiology in the operating room.

Analysis of malpractice claims: The Franco-Belgian "Cœlio Club" experience.

Malpractice claims are a regularly increasing concern in gastrointestinal surgery. The goal of this study was to compare the current status of claims in two different French-speaking communities by a retrospective descriptive study of surgeons' experiences, from the beginning of their practice up until December 31 2014. Data included the number, the reasons, and the results of medicolegal claims and their jurisdictions. Forty-three surgeons participated in this study. Two hundred medicolegal claims were analyzed. The mean number was 5.8 per surgeon. Bariatric surgery, colorectal surgery and parietal surgery were the most exposed. Forty-six (23%) faults were noted, while no fault was pronounced in 139 (69.5%) cases. The main reasons for lodging complaints were nosocomial infections, anastomotic leaks, poor postoperative care, hollow organ perforation, peripheral neurologic complication, and insufficient preoperative information. Forty-four percent of the complaints were analyzed by the conciliation and compensation commissions and 43.5% by the High Court. In the French-speaking group, there were 13 complaints, two of which gave rise to compensation. French surgeons are highly exposed to complaints: in French law, clumsiness or technical maladdress is considered as a fault. The patient should be informed preoperatively of all possible severe risks of a medical procedure. In Belgium, complications are exceptional and are considered random therapeutic events. Adhering to the recommendations emanating from the French High Authority of Health and Learned Societies as well as accreditation issued by the same High Authority should allow to decrease the number of undesirable events related to care and malpractice.

Medical expert witness testimony in France and in Europe.

Health care professionals are usually at a loss when it comes to medical "complaints", essentially because they lack knowledge with regard to existing litigation procedures. After a short reminder of the different rights of appeal in France, we describe how medical appeals function in other European countries. Next, we give the details of how the evaluation of claims of bodily damage works, a process in which every physician may be called upon to participate several times in a career, either as the defendant, or as a medical counselor, or as an expert. The goal of this update is to understand the different compensation appeal circuits available to patients and help the surgeon demystify and dedramatize the situation while preparing for the medical expert witness testimony. All such testimony reports, via whatever appeal circuit, follow a similar procedure, even if they are not exactly identical.

Expert witness testimony step by step and how to prepare it.

The medical expert witness testimony is a key moment in the pathway of patient complaints as well as in the line of defense of the defendant-physician. For the defendant, it is a difficult time, often experienced as humiliating, because his or her competences are questioned, appraised and discussed in public. However, the defendant must perceive and use this encounter as an opportunity to express his/her viewpoint on the medical accident. This article provides the principal juridical rules that govern the medical expert witness testimony that must be known, as well as some practical advice on how the medical expert witness testimony evolves and how to protect oneself from the complaints, In order to enable the defendant to best prepare for this confrontation between the involved parties.

The nitrogen concentration effect on Ce doped SiOxNy emission: towards optimized Ce3+ for LED applications.

Ce-Doped SiOxNy films are deposited by magnetron reactive sputtering from a CeO2 target under a nitrogen reactive gas atmosphere. Visible photoluminescence measurements regarding the nitrogen gas flow reveal a large emission band centered at 450 nm for a sample deposited under a 2 sccm flow. Special attention is paid to the origin of such an emission at high nitrogen concentration. Different emitting centers are suggested in Ce doped SiOxNy films (e.g. band tails, CeO2, Ce clusters, Ce3+ ions), with different activation scenarios to explain the luminescence. X-ray photoelectron spectroscopy (XPS) reveals the exclusive presence of Ce3+ ions whatever the nitrogen or Ce concentrations, while transmission electron microscopy (TEM) shows no clusters or silicates upon high temperature annealing. With the help of photoluminescence excitation spectroscopy (PLE), a wide excitation range from 250 nm up to 400 nm is revealed and various excitations of Ce3+ ions are proposed involving direct or indirect mechanisms. Nitrogen concentration plays an important role in Ce3+ emission by modifying Ce surroundings, reducing the Si phase volume in SiOxNy and causing a nephelauxetic effect. Taking into account the optimized nitrogen growth parameters, the Ce concentration is analyzed as a new parameter. Under UV excitation, a strong emission is visible to the naked eye with high Ce3+ concentration (6 at%). No saturation of the photoluminescence intensity is observed, confirming again the lack of Ce cluster or silicate phase formation due to the nitrogen presence.

Lucifer Yellow filling of area X-projecting neurons in the high vocal center of female canaries.

The avian high vocal center (HVC) is a complex forebrain nucleus that coordinates the sensorimotor integration necessary for song learning and production. It receives auditory and potentially somatosensory input, and sends major projections to vocal motor and anterior forebrain nuclei. The HVC has at least four morphological classes of neurons for which the connectivity remains uncertain. Previous studies have alluded to the functional identity of the cell classes, but none have provided the definitive evidence necessary for subsequent identification of behaviorally relevant changes within known neuronal populations. The cell filling technique we have adapted for use in the song system provides a method by which hodologically identified classes can be described with precision, and song related changes in their morphology can be readily identified. Neurons in female canaries (Serinus canarius) that project to Area X of the anterior forebrain pathway were retrogradely labeled, selectively filled with Lucifer Yellow in a fixed slice preparation, and converted to a Golgi-like stain through an immunocytochemical reaction. We have identified Area X-projecting neurons as belonging to the thick dendrite class of Nixdorf et al. [B.E. Nixdorf, S.S. Davis, T.J. DeVoogd, Morphology of golgi-impregnated neurons in hyperstriatum ventralis, pars caudalis in adult male and female canaries, J. Comp. Neurol. 284 (1989) 337-349] and have shown definitively that they are among the HVC neurons that can receive direct auditory input, as this cell class has short dendrites that extend into the shelf region ventral to HVC that is known to receive auditory inputs. Well-filled axons had collaterals that ramified and terminated within the nucleus, demonstrating a network through which Area X-projecting cells can contribute to intrinsic HVC communication.

[Surgery of aneurysms of the abdominal aorta. Clinical study and surgical results. Apropos of a series of 54 cases]. / La chirurgie des anévrysmes de l'aorte abdominale. Etude clinique et résultats chirurgicaux. A propos d'une série de 54 cas.

54 patients with an abdominal aortic aneurysm were hospitalized between 1969 and 1980 in the Clinic of Cardiovascular and Thoracic Surgery at Rennes (Pr. Y. Logeais): 35 were ruptured aneurysms, 19 non-ruptured. The average age of the patients was 70.6 years. 48% of patients showed signs of atheroma in at least one other site. 24% had arterial hypertension. Arteriography was carried out in 51.5% of the non-ruptured aneurysm cases and in 26% of the ruptured cases. Both ultrasound and tomography are regarded presently as very useful tests. The intervention carried out in 41 patients always involved the insertion of a by-pass graft (aortic only in 7 cases; aorto-biiliac in 19 cases; aorto-bifemoral in 15 cases). Mortality was 7.7% for the non-ruptured aneurysms. 59% for the ruptured aneurysms, the deaths above all being related to the degree of visceral ischaemia. Secondary mortality was comparable for all the aneurysms operated on. More than 80% of patients were surviving 5 years after surgery.

[Terminalized lateral colostomy]. / Colostomie latérale terminalisée.

Complete diversion of the digestive transit requires intestinal section and terminal rather than lateral colostomy. This can now be achieved by using a mechanical stapler to obturate temporarily the distal end of the colonic segment bearing a conventional lateral colostomy, then performing an extra-mucosal anastomosis to re-establish continuity. This technique can be applied to protect low colonic anastomoses or to treat a minor anastomotic disruption. It can also be extended to ileostomy.

[Detection of intra-abdominal suppuration. Value of scintigraphy with indium-111-labeled autologous polynuclears]. / Recherche des collections suppurées intra-abdominales. Intérêt de la scintigraphie aux polynucléaires autologues marqués à l'indium 111.

Between February, 1982 and August, 1983, 53 patients with symptoms suggestive of post-operative intra-abdominal abscess were explored by scintigraphy with indium-111 labeled autologous polymorphonuclears. The sensitivity and specificity of this method were both 96%. Scintigraphy of course must be preceded by ultrasonic exploration which is of more delicate interpretation as well as less sensitive (60%) and less specific (84%). The results of scintigraphy avoided an unnecessary laparotomy in more than one-half of the patients.

[Spontaneous rupture of the esophagus]. / La rupture spontanée de l'oesophage.

Eighteen patients (16 men and two women), aged 20 to 77 years, were admitted to the University hospital between 1973 and 1984 for a Boerhaave's syndrome. Fourteen over eighteen were more than forty years old. Other particular features were the frequency of alcoholism (11 patients) and the lack of preexisting gastrointestinal symptomatology. The cardinal symptom, pain, occurred in 17 cases. It was preceded in 10 subjects by vomiting. Subcutaneous emphysema was only found in five patients, but standard chest X-ray showed seven times a pneumomediastinum. Pleural effusion was present in 14 subjects. Thirteen patients underwent thoracotomy: five within 48 h (1 death) and eight after 48 h (4 deaths); two further deaths were due to withholding surgery, and a third by performing bipolar oesophageal exclusion at a late stage (8th day); six of these deaths were related to local infection. The clinical and radiological features of Boerhaave's syndrome are presented in a review of the literature; particular attention is paid to the various methods of treatment.

Prevention of parastomal hernia by intraperitoneal onlay mesh reinforcement at the time of stoma formation.

PURPOSE: Parastomal hernia (PSH) is a very frequent complication after creation of a permanent colostomy. The aim of this study is to assess the safety and prophylactic effect of intraperitoneal onlay mesh (IPOM) reinforcement of the abdominal wall at the time of primary stoma formation to prevent PSH occurrence. MATERIALS AND METHODS: This multicentre prospective study concerned 20 patients operated for low rectal carcinoma between 2008 and 2010. Those patients had an elective and potentially curative abdominoperineal excision associated with IPOM reinforcement of the abdominal wall with a round composite mesh centred on the stoma site and covering the lateralised colon. There were 8 men and 12 women with a median age of 69 years (range: 44-88) and a body mass index of 27 (range: 21-35). The major outcomes analysed in the study were operative time, complications related to mesh and PSH occurrence. Patients were evaluated 1 month after surgery and then every 6 months with physical examination and computed tomography scan (CT-scan). For PSH, we used the classification of Moreno-Matias. RESULTS: Surgery was performed by laparoscopy in 17 patients and by laparotomy in 3; 12 had an extraperitoneal colostomy, and 8 had a transperitoneal colostomy. The median size of the mesh was 15 cm (range: 12-15). The median operative time was 225 min (range: 175-300), and specific time for mesh placement was 15 min (range: 12-30). One month after surgery, one patient presented with a mild stoma stenosis that was treated successfully by dilatation. With a median follow-up of 24 months (range: 6-42), no other complication potentially related to the use of the mesh was recorded and no mesh had to be removed. On clinical examination, one patient (1/20 = 5 %) had a stoma bulge that appeared a few months after surgery, but was not associated with symptoms. CT-scan evaluation confirmed that all the patients with a normal clinical examination had no PSH and revealed that the patient with the stoma bulge had a stoma loop hernia (type 1a hernia). This patient was followed up for 36 months, no clinical or radiological aggravation of the stoma loop hernia was observed, and he remained totally asymptomatic. CONCLUSIONS: With 95 % of excellent results, IPOM reinforcement at the time of end colostomy formation in selected patients is a very promising procedure. A drawback of this technique is the possibility of developing a stoma loop hernia due to sliding of the exiting colon between the covering mesh and the abdominal wall. However, this risk is low, and no adverse clinical consequence for the patient was noted in our series.

Intraoperative events and their outcome: data from 4007 laparoscopic interventions by the French "Club Cœlio".

AIM: To assess the operative and postoperative course of intraoperative events occurring in laparoscopic surgery according to the classification of Clavien. This evaluation aims at ascertaining morbidity and mortality of abdominal laparoscopic operations, thus serving as a reference for future comparative studies. METHOD: Twenty-nine senior surgeons, all of them members of the Cœlio Club prospectively and consecutively summarized all their laparoscopic activity over a period of 6 months. RESULTS: Of 4007 patients, 373 (9.31%) developed complications, 69 (1.72%) requiring surgery. Establishing the pneumoperitoneum and trocar placement caused 15 vascular (0.37%) and six visceral (0.15%) injuries; seven vascular (0.17%) and 22 visceral (0.55%) injuries occurred intraoperatively. Surgery of the colon and especially the rectum were associated with the highest morbidity with Clavien grades III, IV and V reported in 8, 10 and 15.97% of patients, respectively; 1.2% occurred in biliary surgery and 0.67% in inguinal/femoral hernia repair. CONCLUSION: The prevalence of surgical intraoperative events and postoperative complications is higher than reported in the literature. Clavien's classification is applicable to abdominal laparoscopic surgery; further information is necessary to assess intraoperative surgical events as well as conversions.

On the nature of the stretched exponential photoluminescence decay for silicon nanocrystals.

The influence of hydrogen rate on optical properties of silicon nanocrystals deposited by sputtering method was studied by means of time-resolved photoluminescence spectroscopy as well as transmission and reflection measurements. It was found that photoluminescence decay is strongly non-single exponential and can be described by the stretched exponential function. It was also shown that effective decay rate probability density function may be recovered by means of Stehfest algorithm. Moreover, it was proposed that the observed broadening of obtained decay rate distributions reflects the disorder in the samples.