Influence of X-Ray Irradiation During Photoemission Studies on Halide Perovskite-Based Devices

Metal halide perovskites (MHPs) are semiconductors with promising application in optoelectronic devices, particularly, in solar cell technologies. The chemical and electronic properties of MHPs at the surface and interfaces with adjacent layers dictate charge transfer within stacked devices and ultimately the efficiency of the latter. X-ray photoelectron spectroscopy is a powerful tool to characterize these material properties. However, the X-ray radiation itself can potentially affect the MHP and therefore jeopardize the reliability of the obtained information. In this work, the effect of X-ray irradiation is assessed on Cs0.05 MA0.15 FA0.8 Pb(I0.85 Br0.15 )3  (MA for CH3 NH3 , and FA for CH2 (NH2 )2 ) MHP thin-film samples in a half-cell device. There is a comparison of measurements acquired with synchrotron radiation and a conventional laboratory source for different times. Changes in composition and core levels binding energies are observed in both cases, indicating a modification of the chemical and electronic properties. The results suggest that changes observed over minutes with highly brilliant synchrotron radiation are likely occurring over hours when working with a lab-based source providing a lower photon flux. The possible degradation pathways are discussed, supported by steady-state photoluminescence analysis. The work stresses the importance of beam effect assessment at the beginning of XPS experiments of MHP samples.

Humidity-Induced Degradation Processes of Halide Perovskites Unveiled by Correlative Analytical Electron Microscopy

Improving the stability of lead halide perovskite solar cells (PSCs) for industrialization is currently a major challenge. It is shown that moisture induces changes in global PSC performance, altering the nature of the absorber through phase transition or segregation. Understanding how the material evolves in a wet environment is crucial for optimizing device performance and stability. Here, the chemical and structural evolution of state-of-the-art hybrid perovskite thin-film Cs0.05 (MA0.15 FA0.85 )0.95 Pb(I0.84 Br0.16 )3 (CsMAFA) is investigated after aging under controlled humidity with analytical characterization techniques. The analysis is performed at different scales through Photoluminescence, X-ray Diffraction Spectroscopy, Cathodoluminescence, Selected Area Electron Diffraction, and Energy Dispersive X-ray Spectroscopy. From the analysis of the degradation products from the perovskite layer and by the correlation of their optical and chemical properties at a microscopic level, different phases such as lead-iodide (PbI2 ), inorganic mixed halide CsPb(I0.9 Br0.1 )3 and lead-rich CsPb2 (I0.74 Br0.26 )5 perovskite are evidenced. These phases demonstrate a high degree of crystallinity that induces unique geometrical shapes and drastically affects the optoelectronic properties of the thin film. By identifying the precise nature of these specific species, the multi-scale approach provides insights into the degradation mechanisms of hybrid perovskite materials, which can be used to improve PSC stability.

Assessment and comparison of image quality between two real-time sequences for dynamic MRI of distal joints at 3.0 Tesla

BACKGROUND

Real-time sequences allow functional evaluation of various joint structures during a continuous motion and help understand the pathomechanics of underlying musculoskeletal diseases.

PURPOSE

To assess and compare the image quality of the two most frequently used real-time sequences for joint dynamic magnetic resonance imaging (MRI), acquired during finger and ankle joint motion.

MATERIAL AND METHODS

A real-time dynamic acquisition protocol, including radiofrequency (RF)-spoiled and balanced steady-state free precession (bSSFP) sequences, optimized for temporal resolution with similar spatial resolution, was performed using a 3.0-T MRI scanner on 10 fingers and 12 ankles from healthy individuals during active motion. Image quality criteria were evaluated on each time frame and compared between these two sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were determined and compared from regions of interest placed on cortical bone, tendon, fat, and muscle. Visualization of anatomical structures and overall image quality appreciation were rated by two radiologists using a 0-10 grading scale.

RESULTS

Mean CNR was significantly higher with bSSFP sequence compared to RF-spoiled sequence. The grading score was in the range of 5-9.3 and was significantly higher with RF-spoiled sequence for bone and joint evaluation and overall image appreciation on the two joints. The standard deviation for SNR, CNR, and grading score during motion was smaller with RF-spoiled sequence for both the joints. The inter-reader reliability was excellent (>0.75) for evaluating anatomical structures in both sequences.

CONCLUSION

A RF-spoiled real-time sequence is recommended for the in vivo clinical evaluation of distal joints on a 3.0-T MRI scanner.

In-Depth Chemical and Optoelectronic Analysis of Triple-Cation Perovskite Thin Films by Combining XPS Profiling and PL Imaging

The investigation of chemical and optoelectronic properties of halide perovskite layers and associated interfaces is crucial to harness the full potential of perovskite solar cells. Depth-profiling photoemission spectroscopy is a primary tool to study the chemical properties of halide perovskite layers at different scales from the surface to the bulk. The technique employs ionic argon beam thinning that provides accurate layer thicknesses. However, there is an urgent need to corroborate the reliability of data on chemical properties of halide perovskite thin films to better assess their stability. The present study addresses the question of the Ar⁺ sputtering thinning on the surface chemical composition and the optoelectronic properties of the triple-cation mixed-halide perovskite by combining X-ray photoemission spectroscopy (XPS) and photoluminescence (PL) spectroscopy. First, XPS profiling is performed by Ar⁺ beam sputtering on a half-cell: glass/FTO/c-TiO₂/perovskite. The resulting profiles show a very homogeneous and reproducible element distribution until near the buried interface; therefore, the layer is considered as quasihomogeneous all over its thickness, and the sputtering process is stable. Second, we evaluated a set of thinned perovskite layers representative of selected steps along the profile by means of PL imaging optical measurements in both steady-state and transient regimes to assess possible perturbation of the optical properties from the surface to bulk. Obtained PL spectra inside the resulting craters show no peak shift nor phase segregation. Accordingly, the transient PL measurements do not reveal any changes of the surface recombination rate in the sputtered areas. This demonstrates that there is no cumulative effect of sputtering nor drastic chemical and optoelectronic modifications, validating the determination of the in-depth composition of the perovskite layer. Combining XPS profiling with PL characterization can be a precise tool to be applied for an extensive study of the multiple layers and mixed organic/inorganic interfaces of photovoltaic devices.

Iterative method for optical modelling of perovskite-based tandem solar cells

We present an iterative method to model the optical properties of a complete semitransparent perovskite solar cell. It is based on spectroscopic characterizations and accounts for porosity and incoherence effects. We provide the complex refractive indices of each layer, and we identify the main sources of optical losses. The optical model is also coupled to an electrical model of 4T perovskite/silicon tandem solar cells. It allows to evaluate the interplay between the optical and electrical losses, and the balance between the efficiency of the top and bottom cells. These models provide an effective way to design future tandem devices.

Industrially Compatible Fabrication Process of Perovskite-Based Mini-Modules Coupling Sequential Slot-Die Coating and Chemical Bath Deposition

To upscale the emerging perovskite photovoltaic technology to larger-size modules, industrially relevant deposition techniques need to be developed. In this work, the deposition of tin oxide used as an electron extraction layer is established using chemical bath deposition (CBD), a low-cost and solution-based fabrication process. Applying this simple low-temperature deposition method, highly homogeneous SnO₂ films are obtained in a reproducible manner. Moreover, the perovskite layer is prepared by sequentially slot-die coating on top of the n-type contact. The symbiosis of these two industrially relevant deposition techniques allows for the growth of high-quality dense perovskite layers with large grains. The uniformity of the perovskite film is further confirmed by scanning electron microscopy (SEM)/scanning transmission electron microscopy (STEM) analysis coupled with energy dispersive X-ray spectroscopy (EDX) and cathodoluminescence measurements allowing us to probe the elemental composition at the nanoscale. Perovskite solar cells fabricated from CBD SnO₂ and slot-die-coated perovskite show power conversion efficiencies up to 19.2%. Furthermore, mini-modules with an aperture area of 40 cm² demonstrate efficiencies of 17% (18.1% on active area).

N3 (> 6 cm) squamous cell carcinoma of the head and neck: outcomes and predictive factors in 104 patients

Objective

To report outcome and predictive factors in patients with N3 (> 6 cm) non-metastatic locally advanced head and neck squamous cell carcinoma (LAHNSCC) treated with a conservative approach or with initial surgery.

Methods

104 patients were included: 69 treated with radiotherapy (RT) ± chemotherapy (CT) and 35 with nodal surgery with or without primary tumour resection, which was completed in 30 patients by adjuvant RT ± CT. Positron-emission tomography-computed tomography (PET-CT) guided surveillance after RT ± CT was standard.

Results

Two-year overall survival (OS) and locoregional control (LRC) were 39.4% and 37.5%, respectively. In univariate analysis, body mass index (BMI), performance status (PS), p16 status and haemoglobin value influenced OS and disease-free survival (DFS). In multivariate analysis, p16 positive status and BMI ≥ 25 remained independent prognostic factors for better OS (p = 0.023) and DFS (p = 0.002). Only under/normal weight remained an independent and adverse significant prognostic factor in multivariate analysis for regional control (RC). Patients treated with primary RT ± CT had slightly better 2-year OS (43.5% versus 33.3%, p = 0.31).

Conclusions

Patients with N3 LAHNSCC have poor prognosis, but long term LRC is achievable, especially in overweight patients and those with a good PS.

Light-Induced Passivation in Triple Cation Mixed Halide Perovskites: Interplay between Transport Properties and Surface Chemistry

Mixed halide perovskites have attracted a strong interest in the photovoltaic community as a result of their high power conversion efficiency and the solid opportunity to realize low-cost and industry-scalable technology. Light soaking represents one of the most promising approaches to reduce non-radiative recombination processes and thus to optimize device performances. Here, we investigate the effects of 1 sun illumination on state-of-the-art triple cation halide perovskite thin films Cs_0.05(MA_0.14, FA_0.86)_0.95 Pb (I_0.84, Br_0.16)₃ by a combined optical and chemical characterization. Competitive passivation and degradation effects on perovskite transport properties have been analyzed by spectrally and time-resolved quantitative imaging luminescence analysis and by X-ray photoemission spectroscopy (XPS). We notice a clear improvement of the optoelectronic properties of the material, with a increase of the quasi fermi level splitting and a corresponding decrease of methylammonium MA⁺ for short (up to 1 h) light soaking time. However, after 5 h of light soaking, phase segregation and in-depth oxygen penetration lead to a decrease of the charge mobility.

Integration of 18-FDG PET/CT in the Initial Work-Up to Stage Head and Neck Cancer: Prognostic Significance and Impact on Therapeutic Decision Making

Background: The objective of this study was to assess the therapeutic and prognostic impact of integrating18F-fluorodeoxyglucose (18-FDG) positron emission tomography (PET)/computed tomography (CT) into work-up (WU) at initial staging of patients with head and neck squamous cell carcinoma (HNSCC).

Method: 477 consecutive patients (414M/63F, mean age 62.3 ± 9.7 years) with newly diagnosed HNSCC who underwent pre-treatment 18-FDG PET/CT were retrospectively included. The 18-FDG PET/CT stage (sPET) was compared to the conventional work-up stage (sCWU). A group of cancer specialists determined whether integrating PET/CT into WU at initial staging had an impact on the therapeutic decision, classifying the clinical impact as high (change in therapeutic modality), medium (change in the radiotherapy or surgical procedure), or low (modification of TNM staging and/or detection of synchronous cancer without high or medium impact). Three-year overall survival (OS) was considered as primary endpoint of the prognostic analysis.

Results: 18-FDG PET/CT had a clinical impact in 221 patients (46.3%) with a medium or high impact on management in 94 (19.5%) patients. Medium and high impact of 18-FDG PET/CT was statistically equivalent between sCWU-stage I/II and III/IV subgroups (p = 0.02). 42 patients were PET/CT-upstaged from early stage I/II to advanced stage III/IV and had a significantly lower 3-year OS than those with concordant CWU and 18-FDG PET/CT early stage (54.8 vs. 82.6%, p = 0.001).

Conclusion: This study demonstrated that implementing 18-FDG PET/CT in the initial WU of HNSCC provides valuable staging information with a better prognostic stratification. Patient management was modified for any disease stage, even for early stage I-II, with consequences on survival.

Influence of Environment and Light-Stress on the Optoelectronic Properties of Triple-Cation Perovskite Thin Films

In this work, we study the transport properties of triple-cation halide perovskite thin films and their evolution when exposed to air or vacuum and after light-soaking. Transport parameters were investigated by steady-state dark and photocurrent methods as well as by the steady-state photocarrier grating experiment (SSPG) from which the ambipolar diffusion length of thin film materials is estimated. Combined with other characterization measurements, such as photoluminescence and Fourier transform photocurrent spectroscopy, these techniques demonstrate that air plays an important role in the passivation of the surface trap states of the perovskite films. The competition between passivation and degradation of the films under light-soaking was also deeply investigated. Moreover, we show that the degradation of the transport parameters upon light-soaking could be linked mainly to a degradation of the carrier mobility instead of their lifetime.

High Versatility and Stability of Mechanochemically Synthesized Halide Perovskite Powders for Optoelectronic Devices

We show that mechanochemically synthesized halide perovskite powders from a ball milling approach can be employed to fabricate a variety of lead halide perovskites with exceptional intrinsic stability. Our MAPbI₃ powder exhibits higher thermal stability than conventionally processed thin films, without degradation after more than two and a half years of storage and only negligible degradation after heat treatment at 220 °C for 14 h. We further show facile recovery strategies of nonphase-pure powders by simple remilling or mild heat treatment. Moreover, we demonstrate the mechanochemical synthesis of phase-pure mixed perovskite powders, such as (Cs_0.05FA_0.95PbI₃)_0.85(MAPbBr₃)_0.15, from either the individual metal and organic halides or from readily prepared ternary perovskites, regardless of the precursor phase purity. Adding potassium iodide (KI) to the milling process successfully passivated the powders. We also succeeded in preparing a precursor solution on the basis of the powders and obtained uniform thin films for integration into efficient perovskite solar cells from spin-coating this solution. We find the KI passivation remains in the devices, leading to improved performance and significantly reduced hysteresis. Our work thus demonstrates the potential of mechanochemically synthesized halide perovskite powders for long-time storage and upscaling, further paving the way toward commercialization of perovskite-based optoelectronic devices.

Patent Foramen Ovale and Ischemic Stroke in Patients With Pulmonary Embolism: A Prospective Cohort Study

BACKGROUND

Pulmonary embolism (PE) is associated with increased risk for ischemic stroke, but the underlying mechanism remains unclear. The authors hypothesized that paradoxical embolism through patent foramen ovale (PFO) should be the main mechanism.

OBJECTIVE

To determine the frequency of recent ischemic stroke in patients with symptomatic PE according to whether PFO was detected.

DESIGN

Prospective cohort study with masked assessment of stroke outcomes. (ClinicalTrials.gov: NCT01216423).

SETTING

4 French hospital centers.

PARTICIPANTS

361 consecutive patients with symptomatic acute PE from 13 November 2009 through 21 December 2015.

INTERVENTION

Systematic contrast transthoracic echocardiography (TTE) and cerebral magnetic resonance imaging (MRI) within 7 days after enrollment.

MEASUREMENTS

Recent symptomatic or silent ischemic stroke was diagnosed on the basis of clinical examination and cerebral MRI showing a hypersignal on the trace diffusion-weighted image with reduction or pseudonormalization of apparent diffusion coefficient.

RESULTS

Contrast TTE was conclusive in 324 of 361 patients and showed PFO in 43 patients (13%). The median age was 66 years (interquartile range, 54 to 77 years). In total, 51% of patients (145/284) had associated deep venous thrombosis, 91% (279/306) had cardiovascular risk factors, and 10% (16/151) presented with arrhythmia (no difference between PFO and non-PFO groups). Cerebral MRI was conclusive in 315 patients. Recent ischemic stroke was more frequent in the PFO group than in the non-PFO group (9 of 42 patients [21.4%] vs. 15 of 273 patients [5.5%]; difference in proportions, 15.9 percentage points [95% CI, 4.7 to 30.7 percentage points]).

LIMITATION

Because of inconclusive contrast TTE or MRI, 46 patients were excluded from analysis.

CONCLUSION

Frequency of recent ischemic stroke in patients with symptomatic PE was higher in patients with PFO than in those without PFO. This finding supports the hypothesis that paradoxical embolism is an important mechanism of ischemic stroke in patients with PFO.

PRIMARY FUNDING SOURCE

French Ministry of Health.

Prognostic value of textural indices extracted from pretherapeutic 18-F FDG-PET/CT in head and neck squamous cell carcinoma

BACKGROUND

This study aimed at assessing the prognostic value of textural indices extracted from 18F-fluorodeoxyglucose positron-emission tomography (FDG-PET)/CT in a large cohort of patients with head and neck squamous cell carcinomas (HNSCC) of any anatomic subsite and staging.

METHODS

Consecutive patients with HNSCC referred for a pretreatment FDG-PET/CT were retrospectively included and followed up for a minimum of 2 years. Standardized uptake value, metabolic tumor volume (MTV), and textural indices were calculated using LIFEx software. Prognostic significance of parameters was assessed in univariate and multivariate analysis.

RESULTS

Textural indices were extracted in 284 patients (mean age = 63.7±9.6 years). In univariate analysis, MTV and 4 textural indices-Correlation, Entropy, Energy, and Coarseness-were significantly correlated with overall survival (OS). In multivariate analysis, MTV (P = .008) and Correlation (P = .028) remained independently correlated to OS.

CONCLUSION

This study showed that MTV and 1 textural index extracted from pretherapeutic FDG-PET/CT (Correlation) were independent prognostic factors of OS in patients with HNSCC.

Psoas proximal insertion as a simple and reliable landmark for numbering lumbar vertebrae on MRI of the lumbar spine

OBJECTIVE

To evaluate the value of psoas muscle proximal insertion for correct numbering of the lumbar vertebrae in MRI, in particular in case of lumbosacral transitional vertebra (LSTV).

METHODS

Two radiologists assessed 477 MRI scans of the lumbar spine with a sagittal localizer sequence on the whole spine for numbering vertebrae caudally from C2. Proximal insertion of the psoas was determined as the most proximal vertebra with psoas over half of its body on coronal T2 STIR sequence. The last lumbar vertebra was named considering both its number and the presence or absence of LSTV according to Castellvi classification. These same parameters were also assessed on 207 PET-CT scans of another cohort including the whole spine.

RESULTS

Proximal insertion of the psoas was L1 in 94.1% of cases: 98.5% in case of modal anatomy, 81.4% in case of LSTV, and 51.7% in case of missing or supernumerary lumbar vertebra without LSTV. There was no statistically significant difference between MRI and CT data. The inter-reader agreement for determination of psoas proximal insertion was excellent (kappa = 0.96).

CONCLUSION

Proximal insertion of the psoas muscle is a helpful marker for correct numbering of the lumbar vertebrae in MRI and to detect a complete lumbosacral segmentation anomaly.

KEY POINTS

• Proximal insertion of the psoas muscle can be easily identified on a coronal T2 STIR sequence. • Psoas proximal insertion on the spine almost always designates the first lumbar vertebra and is helpful to accurately number all lumbar vertebrae, especially in case of lumbosacral transitional vertebra. • Conversely, when psoas muscle does not insert five lumbar bodies above the apparent lumbosacral joint, the probability of variation in the number of lumbar vertebrae is high.

Highly efficient MoOx-free semitransparent perovskite cell for 4 T tandem application improving the efficiency of commercially-available Al-BSF silicon

In this work, the fabrication of MoOx-free semitransparent perovskite solar cells (PSC) with Power Conversion Efficiencies (PCE) up to 15.7% is reported. Firstly, opaque PSCs up to 19.7% were fabricated. Then, the rear metal contact was replaced by a highly transparent and conductive indium tin oxide (ITO) film, directly sputtered onto the hole selective layer, without any protective layer between Spiro-OMeTAD and rear ITO. To the best of our knowledge, this corresponds to the most efficient buffer layer-free semitransparent PSC ever reported. Using time-resolved photoluminescence (TRPL) technique on both sides of the semitransparent PSC, Spiro-OMeTAD/perovskite and perovskite/TiO2 interfaces were compared, confirming the great quality of Spiro-OMeTAD/perovskite interface, even after damage-less ITO sputtering, where degradation phenomena result less important than for perovskite/TiO2 one. Finally, a 4-terminal tandem was built combining semitransparent PSC with a commercially-available Aluminium Back Surface Field (Al-BSF) silicon wafer. That silicon wafer presents PCE = 19.52% (18.53% after being reduced to cell size), and 5.75% once filtered, to generate an overall 4 T tandem efficiency of 21.18% in combination with our champion large semitransparent PSC of 15.43%. It means an absolute increase of 1.66% over the original silicon wafer efficiency and a 2.65% over the cut Si cell.

Contribution of brain CT in the diagnosis of tuberculous meningitis: a case report from Djibouti

Tuberculous meningitis, a serious disease with high mortality and morbidity, remains frequent in countries with endemic tuberculosis. Its non-specific presentation often delays the introduction of appropriate treatment. Its definitive diagnosis requires isolation of Mycobacterium tuberculosis from cerebrospinal fluid, although this test may be negative without conclusively ruling out this diagnosis. A presumptive diagnosis should be reached as soon as possible through a body of clinical evidence, including the lumbar puncture findings. Brain computed tomography (CT) with and without contrast medium injection is helpful for the diagnosis of tuberculous meningitis and its complications. We discuss the features of CT and their value in relation to a case of tuberculous meningitis in Djibouti, as well as the role of CT in managing this disease.

Management of patients with head and neck cancer (HNC) and synchronic stage I or II lung cancer. SYNCHRON GFPC 15-01 study

e20048

Background: There is few published data’s of the management of patients with a HNC and a synchronic lung cancer. The aim of this observational study was to describe in a multicentric setting the management of these patients. Methods: The study included, consecutively all patients diagnosed between January 2011 and December 2015 in 19 French centers with a HNC and a synchronic lung cancer. Patients were described per the clinical characteristics, management and outcomes. Patient characteristics and treatment information was analyzed descriptively. Kaplan-Meier estimation was used to assess median overall survival. Results: The study included 62 patients: men : 84%; 62 ± 1.3 years old, current smokers: 68%, asbestos exposure: 11%; performans status: 0 and 1 for 22.5% and 66% of the patients respectively; hight rate of comorbidities, cardiovascular: 68%, COPD: 32%. Main histology for HNC was squamous: 98%, in oral cavity: 32%, oropharyngeal: 21%, hypo-pharyngeal: 22.5% and laryngeal: 24%. T classification was T1, T2, T3 and T4 in 18%, 29%, 29% and 16% of cases respectively, and N classification was N0, N1, N2, N3, for 40%, 24%, 21% and 6% of cases respectively. The main treatment was surgery, 47%, and chemo-radiotherapy, 52%. The diagnosis of lung cancer impacts the HNC management in 21% of the cases. Median delay between HNC and first day treatment was 54 ± 6 days. HNC progressive free survival rate was 68% at 2 years. Lung cancers were localized (stages I: 81%, stages II: 19%), squamous: 32%, adeno-carcinomas: 47%, larges cells or sarcomatosis: 7%. Main treatments were surgery: 56%, mainly lobectomy, radiotherapy: 15%, radio-chemotherapy: 10% and chemotherapy alone: 26%. Six patients didn’t receive active treatment. Median delay of treatment was 150 ± 16 days. Lung cancer progressive free survival rate was 28% at 2 years. OS was 55% at 2 years, better for stage I than stage II lung cancers. Conclusions: Synchronic lung cancer at HCN diagnosis impact management and outcomes of HNC with a delay in the management of lung cancer. Specific recommendations should be elaborate to improve the management of these patients.

Influence of a Boron Precursor on the Growth and Optoelectronic Properties of Electrodeposited Zinc Oxide Thin Film

Highly transparent and conductive materials are required for many industrial applications. One of the interesting features of ZnO is the possibility to dope it using different elements, hence improving its conductivity. Results concerning the zinc oxide thin films electrodeposited in a zinc perchlorate medium containing a boron precursor are presented in this study. The addition of boron to the electrolyte leads to significant effects on the morphology and crystalline structure as well as an evolution of the optical properties of the material. Varying the concentration of boric acid from 0 to 15 mM strongly improves the compactness of the deposit and increases the band gap from 3.33 to 3.45 eV. Investigations were also conducted to estimate and determine the influence of boric acid on the electrical properties of the ZnO layers. As a result, no doping effect effect by boron was demonstrated. However, the role of boric acid on the material quality has also been proven and discussed. Boric acid strongly contributes to the growth of high quality electrodeposited zinc oxide. The high doping level of the film can be attributed to the perchlorate ions introduced in the bath. Finally, a ZnO layer electrodeposited in a boron rich electrolyte was tested as front contact of a Cu(In, Ga)(S, Se)2 based solar cell. An efficiency of 12.5% was measured with a quite high fill factor (>70%) which confirms the high conductivity of the ZnO thin film.

Zinc oxide as a hole blocking layer for perovskite solar cells deposited in atmospheric conditions

A sputtered ZnO thin film was used as electron extraction layer, in a planar perovskite based solar cell. As a result a maximum power conversion efficiency (PCE) of 14.2%, measured at reverse scan, has been demonstrated.

Electrodeposition of ZnO window layer for an all-atmospheric fabrication process of chalcogenide solar cell

This paper presents the low cost electrodeposition of a transparent and conductive chlorine doped ZnO layer with performances comparable to that produced by standard vacuum processes. First, an in-depth study of the defect physics by ab-initio calculation shows that chlorine is one of the best candidates to dope the ZnO. This result is experimentally confirmed by a complete optical analysis of the ZnO layer deposited in a chloride rich solution. We demonstrate that high doping levels (>10(20) cm(-3)) and mobilities (up to 20 cm(2) V(-1) s(-1)) can be reached by insertion of chlorine in the lattice. The process developed in this study has been applied on a CdS/Cu(In,Ga)(Se,S)2 p-n junction produced in a pilot line by a non vacuum process, to be tested as solar cell front contact deposition method. As a result efficiency of 14.3% has been reached opening the way of atmospheric production of Cu(In,Ga)(Se,S)2 solar cell.

Value of spontaneous hyperdensity of cerebral venous thrombosis on helical CT

BACKGROUND

Excluding a cerebral venous thrombosis (CVT) through imaging is a frequent request in the emergency setting. This assessment often starts by an unenhanced brain computed tomography (CT).

PURPOSE

Re-evaluate the value of spontaneous hyperdensity of CVT on helical unenhanced brain CT.

METHODS

Multicentric retrospective study on CVT probability based on visual assessment of spontaneous hyperdensity of cerebral venous system, performed by four blinded radiologists, individually then collectively, on a population including 14 helical unenhanced brain CTs with CVT and 102 unenhanced brain CTs without CVT (all confirmed by CT or magnetic resonance [MR] venography). Exclusion criteria: no DICOM image, symptoms >15 days, CVT indirect signs on unenhanced CT. A fifth radiologist set 768 regions of interest to measure and to compare the density within the normal venous sinuses and the CVTs.

RESULTS

After consensus reading, sensitivity of this sign for CVT diagnosis was 100%, specificity 95.1%, and negative predictive value (NPV) 100%, with high individual NPV (99-100%). Area under the receiver-operating characteristic curve was 0.992 after consensus (0.976-0.986 individually). The spontaneous density was significantly different (P <0.05) between normal sinuses and CVTs, with a density >70 HU reported only within the CVTs, except for the horizontal part of the superior sagittal sinus (hSSS).

CONCLUSION

The dense triangle sign on helical unenhanced brain CT has an excellent NPV to exclude a sinus thrombosis during the first 2 weeks. However, we believe that visual assessment of spontaneous hyperdensity is not sufficient for the diagnosis of CVT, with possible false-positive of the hSSS on unenhanced CT.

Ultrasonographic evaluation of gastric content during labour under epidural analgesia: a prospective cohort study

BACKGROUND

Women in labour are considered at risk of gastric content aspiration partly because the stomach remains full before delivery. Ultrasonographic measurement of antral cross-sectional area (CSA) is a validated method of gastric content assessment. Our aim was to determine gastric content volume and its changes in parturients during labour under epidural analgesia using bedside ultrasonography.

METHODS

The cut-off value corresponding to an increased gastric content was determined by ultrasound measurement of antral CSA in six pregnant women in late pregnancy before and after ingestion of 250 ml of non-clear liquid. Antral CSA was then measured twice in 60 parturients who presented in spontaneous labour: when the anaesthesiologist was called for epidural analgesia catheter placement, and at full cervical dilatation. Patient-controlled epidural analgesia was performed with a solution of ropivacaine and sufentanil.

RESULTS

After liquid ingestion, antral CSA (mm(2)) increased from 90 (range, 80-151) to 409 (range, 317-463). A CSA of 320 was taken as cut-off value. The feasibility rate of antral CSA determination was 96%. CSA decreased from 319 [Q1 158-Q3 469] to 203 [Q1 123-Q3 261] during labour (P=2×10(-7)). CSA was >320 in 50% of parturients at the beginning of labour vs 13% at full cervical dilatation (P=0.006).

CONCLUSIONS

Bedside ultrasonographic antral CSA measurement is feasible in pregnant women during labour and easy to perform. The observed decrease in antral CSA during labour suggests that gastric motility is preserved under epidural anaesthesia. The procedure could be used to assess individual risk of gastric content aspiration during labour.

Clinical-radiological correlation after functional endoscopic sinus surgery in patients with chronic rhinosinusitis: interest of a sinonasal aerial volumetry

BACKGROUND

Although a CT scan is often performed after functional endoscopic sinonasal surgery (FESS) in patients with chronic rhinosinusitis, its role hasn`t been firmly established. The goal of this study is to investigate the correlation between symptoms and CT findings before and after FESS for chronic rhinosinusitis. In addition, the interobserver agreement for both sinonasal aerial volumetry and CT score is assessed.

METHODS

Thirty-three patients surgically treated for chronic rhinosinusitis were included in this prospective study. Conventional and modified Lund-Mackay scores and sinonasal volumetry were determined by two radiologists before (M0), at 3 months (M3) and 1 year (M12) after surgery. The symptoms were evaluated by the 22-item SinoNasal Outcome Test (SNOT-22).

RESULTS

Change of SNOT-22 and air volume were significantly correlated between M0 and M12, but not between M0 and M3, for both readers. Compared to other scores, volume had the best intraclass correlation coefficient and reproducibility, according to the Bland-Altman analysis. No correlation was found between SNOT-22 and CT scores before and after surgery, except between M12 and M0 for one reader.

CONCLUSION

The correlation between CT scan and symptoms is low or absent. The measurement of sinonasal air volume is best correlated with the symptoms after surgery, with the best inter-observer agreement.

Early prediction of survival following induction chemotherapy with DCF (docetaxel, cisplatin, 5-fluorouracil) using FDG PET/CT imaging in patients with locally advanced head and neck squamous cell carcinoma

PURPOSE

Locally advanced head and neck squamous cell carcinoma (HNSCC) has a high rate of recurrence. Induction chemotherapy with DCF (docetaxel, cisplatin, 5-fluorouracil) before chemoradiotherapy could lead to the best disease control of inoperable stage III/IV HNSCC but with an increased risk of acute toxicity. Early assessment of therapeutic efficacy is a key issue in considering the benefit of escalation in a poor prognosis population.

METHODS

Patients with stage III/IV HNSCC, in whom DCF induction chemotherapy followed by concurrent chemoradiotherapy had been validated by a multidisciplinary team, were prospectively included in the study. FDG PET/CT scans were performed in all patients before and after two of the three cycles of DCF. EORTC99 criteria were used to evaluate PET responses as follows: group 1 (metabolic responders) showing a complete response (CR) or partial response (PR), and subgroup 0 (metabolic nonresponders) showing stable disease (SD) or progressive disease (PD). The primary endpoint for monitoring patients was event-free survival (EFS). EFS probabilities between the two groups were estimated by the Kaplan-Meier method and statistically compared using the log-rank test.

RESULTS

Fifteen consecutive patients (14 men, 1 woman; age 57.5 ± 6.2 years, mean ± SD) were analysed. Therapeutic assessment by PET/CT demonstrated CR in four patients, PR in six, SD in four and PD in one. Among the ten patients with a metabolic response (group 1), none had relapsed at the time of this report, while four of five patients with no metabolic response (group 0) showed recurrence within an average of 9.0 ± 1.6 months. Median EFS was, respectively, 18.9 months (3.8-25.3 months) and 10.2 months (7.5-12.7 months) in group 1 and group 0. The corresponding 1-year EFS rates were 100 % and 20 %, respectively. The difference in EFS between the two groups was statistically significant (p = 0.0014).

CONCLUSION

Early therapeutic response demonstrated on FDG PET/CT after two cycles of induction chemotherapy with DCF in patients with inoperable stage III/IV HNSCC seems to be a predictive factor for EFS.

FAMM FLAP in Head and Neck Surgery

Objective: Facial artery mucosa musclar (FAMM) flap is mainly used in head and neck oncologic surgery for primary reconstruction after resection in oral cavity and in surgical treatment of osteoradionecrosis of the mandible. Some benefits are ease of use, good vitality, and no aesthetic prejudice. Recently, robotic surgery has made removal of the flap inside the mouth cavity easier, thanks to a wider field of view and smaller surgical instruments.

Method: Retrospective study. Forty cases were analyzed in ENT and head and neck center of Brest University Hospital, between April 2007 and June 2011, in both indications primary reconstruction and surgical treatment of osteoradionecrosis. Complications such as infection, hematoma, necrosis, time within pedicle weaning, and resumption of feeding were studied.

Results: Eighteen cases for primary reconstruction and 22 cases for surgical treatment of osteoradionecrosis were analyzed. After radiotherapy, pedicle weaning was delayed (average of 11 more days) and enteral nutrition period lasted longer (average of 22 days vs 7 days). However, no infection and only 1 case of hematoma (2.5%) and 2 cases of necrosis (5%) were identified. Revision surgery for flap removal was necessary in 1 case (2.5%). After 1 month, oral feeding was possible in 35 cases (85%). Eighty percent of bad results occurred after radiotherapy.

Conclusion: Thanks to its reliability, the FAMM flap is a good solution in head and neck cancer surgery, even after radiotherapy. However, the size of this flap remains relatively small. For a medium size loss of substance, it is a good alternative between controlled wound healing and bigger flaps.

Early recurrence or submucosal residual of laryngeal squamous cell carcinoma: diagnosis by CT-guided endolaryngeal core biopsy on a transcutaneous approach

BACKGROUND

Ultrasound and CT-guided biopsy is a common procedure for histologic diagnosis of recurrence of head and neck squamous cell carcinoma. The present study describes a novel CT-guided endolaryngeal puncture site.

METHODS AND RESULTS

A 59-year-old man was treated for a T2N0M0 supraglottic laryngeal tumor by laser resection and bilateral lymph node dissection; exeresis was judged complete. Six-month follow-up found persistent dysphonia. Endoscopic examination and iterative biopsy gave reassuring results, but (18) fluorodeoxyglucose positron emission tomography-CT ((18) FDG PET-CT) found highly suspicious increased right hemilaryngeal metabolic activity. Diagnosis of residual tumor was confirmed on CT-guided endolaryngeal biopsy.

CONCLUSIONS

Image-guided biopsy is the technique of choice in head and neck lesions that are deep or difficult to palpate and inaccessible to endoscopy. It is especially useful when recurrence is suspected after radiation therapy or cancer surgery. Many puncture sites have been reported in the literature; the present novel laryngeal approach extends the range of image-guided biopsy, although further studies will be needed to assess possible morbidity.

Electrodeposition of ZnO nanorod arrays on ZnO substrate with tunable orientation and optical properties

The electrodeposition of ZnO nanorods on ZnO:Al films with different orientations is reported. The influence of the total charge exchanged during electrodeposition on the nanorod's geometry (length, diameter, aspect ratio and surface density) and the optical transmission properties of the nanorod arrays is studied on a [0001]-oriented ZnO:Al substrate. The nanorods are highly vertically oriented along the c axis, following the lattice matching with the substrate. The growth on a [1010] and [1120] ZnO:Al-oriented substrate with c axis parallel to the substrate leads to a systematic deviation angle of 55 degrees from the perpendicular direction. This finding has been explained by the occurrence of a minority orientation with the [1011] planes parallel to the surface, with a preferential growth on corresponding [0001] termination. Substrate crystalline orientation is thereby found to be a major parameter in finely tuning the orientation of the nanorod array. This new approach allows us to optimize the light scattering properties of the films.

[Retrospective study conducted in northern Finistère about the role of breast MRI in normal breast screening, experience in 51 patients]

OBJECTIVES

To study the role and indications of breast MRI in normal breast screening.

PATIENTS AND METHODS

Retrospective study of 51 patients (mean age of 51 years) conducted in northern Finistère. Each patient had a normal (BI-RADS 1 or 2) breast screening (mammography and echography). Four indications for MRI were chosen: screening of high-risk patients, high-density breasts, radio-clinical discordance, and breasts prostheses. Breast MRI were reviewed according to BI-RADS classification. Abnormalities categorized in BI-RADS 4 or 5 were confirmed histologically.

RESULTS

Thirteen patients underwent histological analysis. Nine invasive carcinomas were identified (six invasive lobular carcinomas (ILC), two mixed carcinomas, one invasive ductal carcinoma). For these patients, the reason for performing MRI was a radio-clinical discordance.

DISCUSSION AND CONCLUSION

The study demonstrates the breast MRI value for radio-clinical discordance and the key role of MRI in diagnostic challenge of ILC. In literature review, MRI has a role even if breast screening is normal: radio-clinical discordance, screening of patients with high-risk, breasts prostheses in certain cases. Breast density comes as an additional criteria to perform this exam.