Elucidating the Role of Antisolvents on the Surface Chemistry and Optoelectronic Properties of CsPbBrxI3-x Perovskite Nanocrystals.

Colloidal lead-halide perovskite nanocrystals (LHP NCs) have emerged over the past decade as leading candidates for efficient next-generation optoelectronic devices, but their properties and performance critically depend on how they are purified. While antisolvents are widely used for purification, a detailed understanding of how the polarity of the antisolvent influences the surface chemistry and composition of the NCs is missing in the field. Here, we fill this knowledge gap by studying the surface chemistry of purified CsPbBrxI3-x NCs as the model system, which in itself is considered a promising candidate for pure-red light-emitting diodes and top-cells for tandem photovoltaics. Interestingly, we find that as the polarity of the antisolvent increases (from methyl acetate to acetone to butanol), there is a blueshift in the photoluminescence (PL) peak of the NCs along with a decrease in PL quantum yield (PLQY). Through transmission electron microscopy and X-ray photoemission spectroscopy measurements, we find that these changes in PL properties arise from antisolvent-induced iodide removal, which leads to a change in halide composition and, thus, the bandgap. Using detailed nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR) measurements along with density functional theory calculations, we propose that more polar antisolvents favor the detachment of the oleic acid and oleylamine ligands, which undergo amide condensation reactions, leading to the removal of iodide anions from the NC surface bound to these ligands. This work shows that careful selection of low-polarity antisolvents is a critical part of designing the synthesis of NCs to achieve high PLQYs with minimal defect-mediated phase segregation.

INSIGHT: in situ heuristic tool for the efficient reduction of grazing-incidence X-ray scattering data.

INSIGHT is a Python-based software tool for processing and reducing 2D grazing-incidence wide- and small-angle X-ray scattering (GIWAXS/GISAXS) data. It offers the geometric transformation of the 2D GIWAXS/GISAXS detector image to reciprocal space, including vectorized and parallelized pixel-wise intensity correction calculations. An explicit focus on efficient data management and batch processing enables full control of large time-resolved synchrotron and laboratory data sets for a detailed analysis of kinetic GIWAXS/GISAXS studies of thin films. It processes data acquired with arbitrarily rotated detectors and performs vertical, horizontal, azimuthal and radial cuts in reciprocal space. It further allows crystallographic indexing and GIWAXS pattern simulation, and provides various plotting and export functionalities. Customized scripting offers a one-step solution to reduce, process, analyze and export findings of large in situ and operando data sets.

Modular slot-die coater for in situ grazing-incidence x-ray scattering experiments on thin films.

Multimodal in situ experiments during slot-die coating of thin films pioneer the way to kinetic studies on thin-film formation. They establish a powerful tool to understand and optimize the formation and properties of thin-film devices, e.g., solar cells, sensors, or LED films. Thin-film research benefits from time-resolved grazing-incidence wide- and small-angle x-ray scattering (GIWAXS/GISAXS) with a sub-second resolution to reveal the evolution of crystal structure, texture, and morphology during the deposition process. Simultaneously investigating optical properties by in situ photoluminescence measurements complements in-depth kinetic studies focusing on a comprehensive understanding of the triangular interdependency of processing, structure, and function for a roll-to-roll compatible, scalable thin-film deposition process. Here, we introduce a modular slot-die coater specially designed for in situ GIWAXS/GISAXS measurements and applicable to various ink systems. With a design for quick assembly, the slot-die coater permits the reproducible and comparable fabrication of thin films in the lab and at the synchrotron using the very same hardware components, as demonstrated in this work by experiments performed at Deutsches Elektronen-Synchrotron (DESY). Simultaneous to GIWAXS/GISAXS, photoluminescence measurements probe optoelectronic properties in situ during thin-film formation. An environmental chamber allows to control the atmosphere inside the coater. Modular construction and lightweight design make the coater mobile, easy to transport, quickly extendable, and adaptable to new beamline environments.

Trace Water in Lead Iodide Affecting Perovskite Crystal Nucleation Limits the Performance of Perovskite Solar Cells.

The experimental replicability of highly efficient perovskite solar cells (PSCs) is a persistent challenge faced by laboratories worldwide. Although trace impurities in raw materials can impact the experimental reproducibility of high-performance PSCs, the in situ study of how trace impurities affect perovskite film growth is never investigated. Here, light is shed on the impact of inevitable water contamination in lead iodide (PbI2 ) on the replicability of device performance, mainly depending on the synthesis methods of PbI2 . Through synchrotron-based structure characterization, it is uncovered that even slight additions of water to PbI2 accelerate the crystallization process in the perovskite layer during annealing. However, this accelerated crystallization also results in an imbalance of charge-carrier mobilities, leading to a degradation in device performance and reduced longevity of the solar cells. It is also found that anhydrous PbI2 promotes a homogenous nucleation process and improves perovskite film growth. Finally, the PSCs achieve a remarkable certified power conversion efficiency of 24.3%. This breakthrough demonstrates the significance of understanding and precisely managing the water content in PbI2 to ensure the experimental replicability of high-efficiency PSCs.

Biological variation and reference change values of common clinical chemistry and haematologic laboratory analytes in the elderly population.

BACKGROUND: Biological variation (BV) and reference change values (RCVs) have been widely described for the general population, but the use of these data derived from adults in the elderly population is a controversial issue. We determined the within- and between-subject BV and RCV in both elderly and young people and compared them with previously published analyses. METHODS: Samples were collected from 135 volunteers over 80 years of age at weekly intervals over 4 weeks. Eighteen biochemical and eight haematological analytes were measured. The Fraser and Harris methods were used to calculate the components of BV and RCV. To perform a comparative analysis, a reference group of 118 young subjects was studied under the same conditions. RESULTS: The obtained coefficients of BV showed statistical differences in many cases, but in general, both the elderly and young patient data fall within the ranges previously described for the general population. The indexes of individuality for the analytes investigated did not exceed 1.4 in any case and were <0.6 for some analytes. The RCVs derived from elderly subjects were similar to those published in the young population, both in healthy and diseased individuals. CONCLUSIONS: The strong individuality observed supports the preferential use of RCVs rather than population-based reference intervals in elderly people. For most of the analytes studied, data from the young population can be applied to elderly people, but the specific elderly coefficients of BV and RCVs are a recommended option.

Interobserver agreement for thyroid elastography: value of the quality factor.

OBJECTIVES: The purpose of our study was to investigate interobserver agreement for thyroid ultrasound elastography and to analyze the reproducibility of real-time freehand elastography in thyroid nodules. METHODS: A prospective nonrandomized double-blind study was conducted between September 2008 and June 2010. Real-time elastography of 89 thyroid nodules was performed by two radiologists, with the first radiologist evaluating each thyroid nodule 5 minutes before the second. The elastograms were obtained with the patients holding their breath and considered valid when the quality factor was 50 or higher. The region of interest was positioned to include the nodule and 0.5 cm of surrounding normal thyroid parenchyma but to exclude the carotids and esophageal-tracheal structures. The elastograms were classified on a scale of 5 different patterns. RESULTS: Observers 1 and 2 coincided in 79 elastographic patterns and disagreed on 10 nodules (11.2%). The results between the radiologists had a statistically significant agreement (P < .005), with a κ value of 0.838. CONCLUSIONS: The introduction of a quality factor in elastographic software and the selection of elastograms with a quality factor of 50 or higher confer almost perfect interobserver agreement for thyroid nodule elastography and make elastography a reproducible technique that could be used in daily clinical practice.

Morphological Insights into the Degradation of Perovskite Solar Cells under Light and Humidity.

Perovskite solar cells (PSCs) have achieved competitive power conversion efficiencies compared with established solar cell technologies. However, their operational stability under different external stimuli is limited, and the underlying mechanisms are not fully understood. In particular, an understanding of degradation mechanisms from a morphology perspective during device operation is missing. Herein, we investigate the operational stability of PSCs with CsI bulk modification and a CsI-modified buried interface under AM 1.5G illumination and 75 ± 5% relative humidity, respectively, and concomitantly probe the morphology evolution with grazing-incidence small-angle X-ray scattering. We find that volume expansion within perovskite grains, induced by water incorporation, initiates the degradation of PSCs under light and humidity and leads to the degradation of device performance, in particular, the fill factor and short-circuit current. However, PSCs with modified buried interface degrade faster, which is ascribed to grain fragmentation and increased grain boundaries. In addition, we reveal a slight lattice expansion and PL redshifts in both PSCs after exposure to light and humidity. Our detailed insights from a buried microstructure perspective on the degradation mechanisms under light and humidity are essential for extending the operational stability of PSCs.

Antisolvent Additive Engineering for Boosting Performance and Stability of Graded Heterojunction Perovskite Solar Cells Using Amide-Functionalized Graphene Quantum Dots.

Additive and antisolvent engineering strategies are outstandingly efficient in enhancing perovskite quality, photovoltaic performance, and stability of perovskite solar cells (PSCs). In this work, an effective approach is applied by coupling the antisolvent mixture and multi-functional additive procedures, which is recognized as antisolvent additive engineering (AAE). The graphene quantum dots functionalized with amide (AGQDs), which consists of carbonyl, amine, and long hydrophobic alkyl chain functional groups, are added to the antisolvent mixture of toluene (T) and hexane (H) as an efficient additive to form the CH3NH3PbI3 (MAPI):AGQDs graded heterojunction structure. A broad range of analytical techniques, including scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, space charge limited current, UV-visible spectroscopy, external quantum efficiency, and time-of-flight secondary ion mass spectrometry, are used to investigate the effect of AAE treatment with AGQDs on the quality of perovskite film and performance of the PSCs. Importantly, not only a uniform and dense perovskite film with hydrophobic property is obtained but also defects on the perovskite surface are significantly passivated by the interaction between AGQDs and uncoordinated Pb2+. As a result, an enhanced power conversion efficiency (PCE) of 19.10% is achieved for the champion PSCs treated with AGQD additive, compared to the PCE of 16.00% for untreated reference PSCs. In addition, the high-efficiency PSCs based on AGQDs show high stability and maintain 89% of their initial PCE after 960 h in ambient conditions.

Process-Aid Solid Engineering Triggers Delicately Modulation of Y-Series Non-Fullerene Acceptor for Efficient Organic Solar Cells.

Volatile solids with symmetric π-backbone are intensively implemented on manipulating the nanomorphology for improving the operability and stability of organic solar cells. However, due to the isotropic stacking, the announced solids with symmetric geometry cannot modify the microscopic phase separation and component distribution collaboratively, which will constrain the promotion of exciton splitting and charge collection efficiency. Inspired by the superiorities of asymmetric configuration, a novel process-aid solid (PAS) engineering is proposed. By coupling with BTP core unit in Y-series molecule, an asymmetric, volatile 1,3-dibromo-5-chlorobenzene solid can induce the anisotropic dipole direction, elevated dipole moment, and interlaminar interaction spontaneously. Due to the synergetic effects on the favorable phase separation and desired component distribution, the PAS-treated devices feature the evident improvement of exciton splitting, charge transport, and collection, accompanied by the suppressed trap-assisted recombination. Consequently, an impressive fill factor of 80.2% with maximum power conversion efficiency (PCE) of 18.5% in the PAS-treated device is achieved. More strikingly, the PAS-treated devices demonstrate a promising thickness-tolerance character, where a record PCE of 17.0% is yielded in PAS devices with a 300 nm thickness photoactive layer, which represents the highest PCE for thick-film organic solar cells.

The Influence of CsBr on Crystal Orientation and Optoelectronic Properties of MAPbI3-Based Solar Cells.

Crystal orientations are closely related to the behavior of photogenerated charge carriers and are vital for controlling the optoelectronic properties of perovskite solar cells. Herein, we propose a facile approach to reveal the effect of lattice plane orientation distribution on the charge carrier kinetics via constructing CsBr-doped mixed cation perovskite phases. With grazing-incidence wide-angle X-ray scattering measurements, we investigate the crystallographic properties of mixed perovskite films at the microscopic scale and reveal the effect of the extrinsic CsBr doping on the stacking behavior of the lattice planes. Combined with transient photocurrent, transient photovoltage, and space-charge-limited current measurements, the transport dynamics and recombination of the photogenerated charge carriers are characterized. It is demonstrated that CsBr compositional engineering can significantly affect the perovskite crystal structure in terms of the orientation distribution of crystal planes and passivation of trap-state densities, as well as simultaneously facilitate the photogenerated charge carrier transport across the absorber and its interfaces. This strategy provides unique insight into the underlying relationship between the stacking pattern of crystal planes, photogenerated charge carrier transport, and optoelectronic properties of solar cells.

Reproducibility of shear wave velocity measurements by acoustic radiation force impulse imaging of the liver: a study in healthy volunteers.

OBJECTIVES: The purposes of this study were to investigate interobserver reproducibility using acoustic radiation force impulse imaging and to develop an acoustic radiation force impulse scoring system. METHODS: Fifty healthy volunteers with normal liver function test values were selected for the study. Shear wave velocity measurements, expressed in meters per second, were taken in a deep portion of liver segment 6. Two observers with different levels of experience performed the measurements independently and blindly. RESULTS: All of the measurements taken by the 2 observers were valid, even in volunteers with a body mass index of greater than 28 kg/m(2). The results point to very good interobserver reproducibility of shear wave velocity measurements, with an intraclass coefficient correlation of 0.86 (P < .001). CONCLUSIONS: The results of this study show that shear wave velocity measurements using the acoustic radiation force impulse technique and a standardized protocol are accurate and reproducible.

Effect of SonoVue on the synovial membrane in rabbit knees.

OBJECTIVES: The purpose of this study was to evaluate the effect of intra-articular injection of SonoVue (sulfur hexafluoride with a phospholipid shell; Bracco SpA, Milan, Italy) on the synovial membrane in an animal model. METHODS: Twenty-one New Zealand White rabbits (42 knees) were used in this study. We injected the knees with normal saline (saline group; n = 21) and SonoVue (SonoVue group; n = 21). A histologic examination of the knees was performed out at 3 and 12 hours and 3, 7, 15, 30, and 45 days after injection. Four histologic parameters (synovial hyperplasia, synovial stroma, vascular dilatation, and inflammatory infiltrates) were graded separately. RESULTS: We found no significant differences in this study for synovial hyperplasia, vascular dilatation, or inflammatory infiltrates between the saline and SonoVue groups. A significant difference was only observed for synovial stroma (P < .05), and most of the histologic changes were mild in the saline group and moderate in the SonoVue group. The histologic changes observed in this study are considered transitory and reversible. CONCLUSIONS: The results suggest that intra-articular injection of SonoVue is a safe procedure.

Assessment of liver steatosis in chicken by using acoustic radiation force impulse imaging: preliminary results.

OBJECTIVE: To evaluate acoustic radiation force impulse (ARFI) imaging as a non-invasive tool for quantification of the grades of liver steatosis in chickens. METHODS: We used two different diets: a standard diet (SD group) and a hyperlipidaemic diet (HD group). The ARFI technique was performed in all the animals in the right hepatic lobe and shear wave velocity (SWV) was measured and expressed in metres per second (m/s). Plasma lipid levels were analysed. Steatosis was quantified by using semiquantitative analysis. Statistical analysis was used and Pearson's correlation coefficient was calculated. RESULTS: Mean SWV was 0.94 ± 0.16 m/s (range 0.8-1.3 m/s) in the SD group and 1.91 ± 0.25 m/s (range 1.3-2.2 m/s) in the HD group (p < 0.001). The lowest SWVs (≤1.3 m/s) corresponded to the chickens in the SD group, with 100% of the animals returning a score of 0, whereas the range of SWV in the HD group chickens was between 1.6 and 2.2 m/s. A substantial correlation was observed between SWVs with histological semiquantitative analysis of steatosis (r = 0.85, p < 0.001). CONCLUSION: ARFI imaging is a non-invasive diagnostic tool that allows discrimination between the grades of liver steatosis in chickens.

MR arthrography of the shoulder using an anterior approach: optimal injection site.

OBJECTIVE: The purpose of our study was to optimize anterior MR arthrography of the shoulder by comparing three injection sites. MATERIALS AND METHODS: Seventy-eight patients were divided into three groups of 26 each, according to the injection site selected: the upper third of the medial part of the humeral head, the lower third of the medial part of the humeral head, or the area between the middle and lower thirds of the glenohumeral joint. A marker plate with radiopaque coordinates was used in performing the technique. Radiologist time and exposure time were recorded, and the intensity of the patient's pain was measured using a Visual Analogue Scale (VAS). Groups were compared using variance analysis and the least significant difference method. RESULTS: Shoulder arthrography was considered satisfactory for all three injection sites. Mean exposure time was 20.9 +/- 7.8 (SD) milliseconds, and mean radiologist time was 6.4 +/- 0.8 minutes. Mean pain intensity registered by the VAS was 1.7 +/- 0.9, the lowest values tending to be those recorded by patients who received an injection in the upper third. Exposure and radiologist times were lower for these latter patients; differences between the upper third and the other two areas were statistically significant (p < 0.005). CONCLUSION: The optimal injection site for anterior MR arthrography of the shoulder is the upper third of the humeral head, a simple, rapid procedure that is well tolerated by patients and reduces the radiation dose administered.

Diagnostic efficiency of sestamibi gammagraphy and Doppler sonography in the preoperative assessment of breast lesions.

INTRODUCTION: It would be desirable to have preoperative methods that allow an adequate selection of patients with breast lesions to rule out breast cancer. The aim of the present study is to evaluate the efficiency of preoperative Sestamibi gammagraphy and Doppler sonography regarding the differential diagnosis of malignancy in breast lesions. MATERIAL AND METHODS: A prospective observational study was conducted on 88 consecutive patients with breast lesions. All the patients underwent preoperative Doppler sonography with an echo-enhancing agent and Sestamibi gammagraphy. All the patients had histopathological study of the surgical specimen to compare with the result of the preoperative techniques. These comparisons were done both for the overall series and separately for palpable and non-palpable lesions. RESULTS: In the overall series results, both tests separately and the two combined, are related significantly to the malignant histological diagnosis (p < 0.001). In palpable lesions, there is a considerable increase in sensitivity, and especially in specificity, attaining 100%, with the combination of both tests. In non-palpable lesions, a relationship was only found between the results of the Sestamibi gammagraphy and the malignant histological diagnosis (93.3%; p < 0.05). CONCLUSIONS: Sestamibi gammagraphy and Doppler sonography are two efficient exploratory techniques in the preoperative assessment of malignancy in breast lesions, especially for palpable lesions, and this efficiency is greater when they are combined.

Ultrasound-guided percutaneous thrombin injection for treatment of extrarenal pseudoaneurysm after renal transplantation.

A patient who received two kidney transplants was placed on hemodialysis after failure of both grafts. He had complained of abdominal pain during the preceding month and was found to have a pulsating mass in his right pelvic region. Computed tomography and color Doppler studies showed a large pseudoaneurysm of the common iliac artery. We describe the treatment of this lesion by the use of ultrasound-guided thrombin injection. To the best of our knowledge, this is the first report regarding the use of ultrasound-guided percutaneous thrombin injection for treatment of such a pseudoaneurysm.

[Usefulness of sonographically guided thrombin injection of iatrogenic femoral pseudoaneurysms]. / Utilidad de la inyección de trombina dirigida por ecografía en los seudoaneurismas femorales iatrogénicos después del fracaso de la compresión.

BACKGROUND AND OBJECTIVE: In december 2000, we began to treat iatrogenic femoral pseudoaneurysms with direct thrombin injection under sonographic guidance after failed sonographically guided compression repair. Our purpose was to determine the success and complications rate of this technique. PATIENTS AND METHOD: We treated 50 patients who had iatrogenic femoral pseudoanerysms using direct thrombin injection. A 22-gauge spinal needle was placed into the psudoaneurysm lumen with sonographic guidance, and bovine thrombin (mean dose, 1200 units; range 200-7000 units) was injected under continous color Doppler sonographic visualization. Patient demographics clinical variables, and pseudoaneurysms characteristics were collected. RESULTS: The overall success rate was 98% (49/50). 30 patiens only required one thrombin injection, with mean thrombosis time of 4 s. When more than one injection was required the mean thrombosis time increased to 9,5 s. There was correlation between thrombosis time and the pseudoaneurysm size (p < 0.005); and between pseudoaneurysm size and the dose of thrombin used. No mayor sedation was needed and no recurrent pseudoaneurysms were observed. With the exception of a mild local eritema in one patient no complications were found. CONCLUSION: The thrombin injection under sonographic guidance is a quick, effective and secure method of therapy for the treatment of iatrogenic femoral pseudoaneurysms. Failures and complications are infrequents. At our hospital sonographically guided thrombin injection had replaced compression repair.

Plasma metabolomics reveals a potential panel of biomarkers for early diagnosis in acute coronary syndrome.

Discovery of new biomarkers is critical for early diagnosis of acute coronary syndrome (ACS). Recent advances in metabolomic technologies have drastically enhanced the possibility of improving the knowledge of its physiopathology through the identification of the altered metabolic pathways. In this study, analyses of peripheral plasma from non-ST segment elevation ACS patients and healthy controls by gas chromatography-mass spectrometry (GC-MC) permitted the identification of 15 metabolites with statistical differences (p < 0.05) between experimental groups. Additionally, validation by GC-MC and liquid chromatography-MC permitted us to identify a potential panel of biomarkers formed by 5-OH-tryptophan, 2-OH-butyric acid and 3-OH-butyric acid. This panel of biomarkers reflects the oxidative stress and the hypoxic state that suffers the myocardial cells and consequently constitutes a metabolomic signature of the atherogenesis process that could be used for early diagnosis of ACS.

Reproducibility of sonographic measurements of the median nerve.

OBJECTIVE: The purpose of this study was to evaluate the reproducibility of median nerve cross-sectional area (CSA) measurements using the indirect method (ellipsoid formula) and the direct or tracing method. METHODS: The median nerve CSA was measured in 22 wrists of patients with carpal tunnel syndrome by means of high-frequency sonography. Measurements were made at the level of the pisiform bone by a standardized sonographic examination protocol. Two observers with different levels of experience performed the measurements, independently and blinded. An analysis of reliability was carried out, and the concordance between the methods was determined with parametric statistical tests. RESULTS: The results point to good reproducibility of the median nerve CSA measurements obtained by both methods, whether performed by an experienced observer or by an inexperienced observer after a short learning period. CONCLUSIONS: The results suggest sonography for median nerve CSA measurements is reproducible by either the direct or indirect method when a standardized sonographic examination protocol is used.