Repeat stereotactic radiosurgery for persistent cerebral arteriovenous malformations in pediatric patients.

OBJECTIVE: The purpose of this study was to describe the long-term outcomes and associated risks related to repeat stereotactic radiosurgery (SRS) for persistent arteriovenous malformations (AVMs) in pediatric patients. METHODS: Under the auspices of the International Radiosurgery Research Foundation, this retrospective multicenter study analyzed pediatric patients who underwent repeat, single-session SRS between 1987 and 2022. The primary outcome variable was a favorable outcome, defined as nidus obliteration without hemorrhage or neurological deterioration. Secondary outcomes included rates and probabilities of hemorrhage, radiation-induced changes (RICs), and cyst or tumor formation. RESULTS: The cohort included 83 pediatric patients. The median patient age was 11 years at initial SRS and 15 years at repeat SRS. Fifty-seven children (68.7%) were managed exclusively using SRS, and 42 (50.6%) experienced hemorrhage prior to SRS. Median AVM diameter and volume were substantially different between the first (25 mm and 4.5 cm3, respectively) and second (16.5 mm and 1.6 cm3, respectively) SRS, while prescription dose and isodose line remained similar. At the 5-year follow-up evaluation from the second SRS, nidus obliteration was achieved in 42 patients (50.6%), with favorable outcome in 37 (44.6%). The median time to nidus obliteration and hemorrhage was 35.5 and 38.5 months, respectively. The yearly cumulative probability of favorable outcome increased from 2.5% (95% CI 0.5%-7.8%) at 1 year to 44% (95% CI 32%-55%) at 5 years. The probability of achieving obliteration followed a similar pattern and reached 51% (95% CI 38%-62%) at 5 years. The 5-year risk of hemorrhage during the latency period after the second SRS reached 8% (95% CI 3.2%-16%). Radiographically, 25 children (30.1%) had RICs, but only 5 (6%) were symptomatic. Delayed cyst formation occurred in 7.2% of patients, with a median onset of 47 months. No radiation-induced neoplasia was observed. CONCLUSIONS: The study results showed nidus obliteration in most pediatric patients who underwent repeat SRS for persistent AVMs. The risks of symptomatic RICs and latency period hemorrhage were quite low. These findings suggest that repeat radiosurgery should be considered when treating pediatric patients with residual AVM after prior SRS. Further study is needed to define the role of repeat SRS more fully in this population.

Effect of cerebral arteriovenous malformation location on outcomes of repeat, single-fraction stereotactic radiosurgery: a matched-cohort analysis.

OBJECTIVE: Patients with deep-seated arteriovenous malformations (AVMs) have a higher rate of unfavorable outcome and lower rate of nidus obliteration after primary stereotactic radiosurgery (SRS). The aim of this study was to evaluate and quantify the effect of AVM location on repeat SRS outcomes. METHODS: This retrospective, multicenter study involved 505 AVM patients managed with repeat, single-session SRS. The endpoints were nidus obliteration, hemorrhage in the latency period, radiation-induced changes (RICs), and favorable outcome. Patients were split on the basis of AVM location into the deep (brainstem, basal ganglia, thalamus, deep cerebellum, and corpus callosum) and superficial cohorts. The cohorts were matched 1:1 on the basis of the covariate balancing score for volume, eloquence of location, and prescription dose. RESULTS: After matching, 149 patients remained in each cohort. The 5-year cumulative probability rates for favorable outcome (probability difference -18%, 95% CI -30.9 to -5.8%, p = 0.004) and AVM obliteration (probability difference -18%, 95% CI -30.1% to -6.4%, p = 0.007) were significantly lower in the deep AVM cohort. No significant differences were observed in the 5-year cumulative probability rates for hemorrhage (probability difference 3%, 95% CI -2.4% to 8.5%, p = 0.28) or RICs (probability difference 1%, 95% CI -10.6% to 11.7%, p = 0.92). The median time to delayed cyst formation was longer with deep-seated AVMs (deep 62 months vs superficial 12 months, p = 0.047). CONCLUSIONS: AVMs located in deep regions had significantly lower favorable outcomes and obliteration rates compared with superficial lesions after repeat SRS. Although the rates of hemorrhage in the latency period and RICs in the two cohorts were comparable, delayed cyst formation occurred later in patients with deep-seated AVMs.

Third Stereotactic Radiosurgery for Residual Arteriovenous Malformations: A Retrospective Multicenter Study.

BACKGROUND AND OBJECTIVES: There are no studies evaluating the efficacy and safety of more than 2 stereotactic radiosurgery (SRS) procedures for cerebral arteriovenous malformations (AVM). The aim of this study was to provide evidence on the role of third single-session SRS for AVM residual. METHODS: This multicenter, retrospective study included patients managed with a third single-session SRS procedure for an AVM residual. The primary study outcome was defined as AVM nidus obliteration without AVM bleeding or symptomatic radiation-induced changes (RIC). Secondary outcomes evaluated were AVM obliteration, AVM hemorrhage, asymptomatic, and symptomatic RIC. RESULTS: Thirty-eight patients (20/38 [52.6%] females, median age at third SRS 34.5 [IQR 20] years) were included. The median clinical follow-up was 46 (IQR 14.8) months, and 17/38 (44.7%) patients achieved favorable outcome. The 3-year and 5-year cumulative probability rates of favorable outcome were 23% (95% CI = 10%-38%) and 53% (95% CI = 29%-73%), respectively. The cumulative probability of AVM obliteration at 3 and 5 years after the third SRS was 23% (95% CI = 10%-37%) and 54% (95% CI = 29%-74%), respectively. AVM bleeding occurred in 2 patients, and 1 of them underwent subsequent resection. The cumulative probability rate of post-SRS AVM hemorrhage remained constant at 5.3% (95% CI = 1%-16%) during the first 5 years of follow-up. Transient symptomatic RIC managed conservatively occurred in 5/38 patients (13.2%) at a median time of 12.5 (IQR 22.5) months from third SRS. Radiation-induced cyst formation was noted in 1 patient (4.2%) 19 months post-SRS. No mortality, radiation-associated malignancy, or permanent symptomatic RIC was noted during follow-up. CONCLUSION: A third single-session SRS to treat a residual intracranial AVM offers obliteration in most patients. The risk of RIC was low, and these effects were transient. While not often required, a third SRS can be performed in patients with persistent residual AVMs.

Local control and survival after stereotactic radiosurgery for colorectal cancer brain metastases: an international multicenter analysis.

OBJECTIVE: The goal of this study was to characterize local tumor control (LC), overall survival (OS), and safety of stereotactic radiosurgery for colorectal brain metastasis (CRBM). METHODS: Ten international institutions participating in the International Radiosurgery Research Foundation provided data for this retrospective case series. This study included 187 patients with CRBM (281 tumors), with a median age of 62 years and 56.7% being male. Most patients (53.5%) had solitary tumors, although 10.7% had > 5 tumors. The median tumor volume was 2.7 cm3 (IQR 0.22-8.1 cm3), and the median margin dose was 20 Gy (IQR 18-22 Gy). RESULTS: The 3-year LC and OS rates were 72% and 20%, respectively. Symptomatic adverse radiation effects occurred in 1.6% of patients. In the multivariate analysis, age > 65 years and tumor volume > 4.0 cm3 were significant predictors of tumor progression (hazard ratio [HR] 2.6, 95% CI 1.4-4.9; p = 0.003 and HR 3.4, 95% CI 1.7-6.9; p < 0.001, respectively). Better performance status (Karnofsky Performance Scale score > 80) was associated with a reduced risk of tumor progression (HR 0.38, 95% CI 0.19-0.73; p = 0.004). Patient age > 62 years (HR 1.6, 95% CI 1.1-2.3; p = 0.03) and the presence of active extracranial disease (HR 1.7, 95% CI 1.1-2.4; p = 0.009) were significantly associated with worse OS. CONCLUSIONS: Stereotactic radiosurgery offers a high LC rate and a low rate of symptomatic adverse radiation effects for the majority of CRBMs. The OS and LC favored younger patients with high functional performance scores and inactive extracranial disease.

Maximizing the Recycling of Iron Ore Pellets Fines Using Innovative Organic Binders.

This research work focuses on the practicality of using organic binders for the briquetting of pellet fines. The developed briquettes were evaluated in terms of mechanical strength and reduction behavior with hydrogen. A hydraulic compression testing machine and thermogravimetric analysis were incorporated into this work to investigate the mechanical strength and reduction behavior of the produced briquettes. Six organic binders, namely Kempel, lignin, starch, lignosulfonate, Alcotac CB6, and Alcotac FE14, in addition to sodium silicate, were tested for the briquetting of pellet fines. The highest mechanical strength was achieved using sodium silicate, Kempel, CB6, and lignosulfonate. The best combination of binder to attain the required mechanical strength even after 100% reduction was found to be a combination of 1.5 wt.% of organic binder (either CB6 or Kempel) with 0.5 wt.% of inorganic binder (sodium silicate). Upscaling using an extruder gave propitious results in the reduction behavior, as the produced briquettes were highly porous and attained pre-requisite mechanical strength.

Local Control and Survival Outcomes After Stereotactic Radiosurgery for Brain Metastases From Gastrointestinal Primaries: An International Multicenter Analysis.

BACKGROUND: There are limited data regarding outcomes for patients with gastrointestinal (GI) primaries and brain metastases treated with stereotactic radiosurgery (SRS). OBJECTIVE: To examine clinical outcomes after SRS for patients with brain metastases from GI primaries and evaluate potential prognostic factors. METHODS: The International Radiosurgery Research Foundation centers were queried for patients with brain metastases from GI primaries managed with SRS. Primary outcomes were local control (LC) and overall survival (OS). Kaplan-Meier analysis was used for univariate analysis (UVA) of prognostic factors. Factors significant on UVA were evaluated with a Cox multivariate analysis proportional hazards model. Logistic regressions were used to examine correlations with RN. RESULTS: We identified 263 eligible patients with 543 brain metastases. Common primary sites were rectal (31.2%), colon (31.2%), and esophagus (25.5%) with a median age of 61.6 years (range: 37-91.4 years) and a median Karnofsky performance status (KPS) of 90% (range: 40%-100%). One-year and 2-year LC rates were 83.5% (95% CI: 78.9%-87.1%) and 73.0% (95% CI: 66.4%-78.5%), respectively. On UVA, age >65 years ( P = .001), dose <20 Gy ( P = .006) for single-fraction plans, KPS <90% ( P < .001), and planning target volume ≥2cc ( P = .007) were associated with inferior LC. All factors other than dose were significant on multivariate analysis ( P ≤ .002). One-year and 2-year OS rates were 68.0% (95% CI: 61.5%-73.6%) and 31.2% (95% CI: 24.6%-37.9%), respectively. Age > 65 years ( P = .006), KPS <90% ( P = .005), and extracranial metastases ( P = .05) were associated with inferior OS. CONCLUSION: SRS resulted in comparable LC with common primaries. Age and KPS were associated with both LC and OS with planning target volume and extracranial metastases correlating with LC and OS, respectively. These factors should be considered in GI cancer patient selection for SRS.

Synthesis of Vanadium Carbide by Mechanical Activation Assisted Carbothermic Reduction.

Vanadium carbide is known, for its hardness and other unique properties, as a refractory material. The synthesis of vanadium carbide is always associated with the utilization of expensive active metals, such as aluminum, calcium and magnesium, as a reducing agent to extract the vanadium metal from its corresponding oxide, followed by carbidization. The carbidization of reduced vanadium requires a complicated process and elevated temperature. Mechanical activation to synthesize vanadium carbide from its corresponding oxide and carbon source represents a promising, straightforward and less energy-intensive route. In the present study, vanadium carbide is synthesized by the carbothermic reduction of a mechanically activated mixture of V2O5 and carbon black as reducing agents without any additives. The reduction process is monitored by means of thermogravimetric analysis. The reduction products are characterized by X-ray diffraction and field emission scanning electron microscope. It is found that V8C7 with an average crystallite size of 88 nm can be synthesized from a V2O5-C mixture after milling for 15 h and further heating at 1050 °C for 1 h in an inert atmosphere.

Lettuce plant growth and tipburn occurrence as affected by airflow using a multi-fan system in a plant factory with artificial light.

A multi-fan system (MFS) for single culture beds was developed to improve the airflow in a plant factory with artificial light. The MFS had seven fans which were installed on both the front and back sides of culture beds to generate airflow from two opposite horizontal directions. The fans that push the air into the culture bed were air inlets while those that pull the air out of the culture bed were air outlets. In this study, three airflow patterns were evaluated: T1, the front and back sides of the culture bed were air inlets; T2, the front side was an air inlet and the backside was an air outlet; and T3, both the front and back sides were air outlets. A culture bed with no MFS was used as a control (T4). Lettuce growth and tipburn occurrence were evaluated and leaf boundary layer resistance (1/gbv), sensible heat flux (Sh), and latent heat flux (Lh) of lettuce plants were estimated. The airflow pattern in T1 improved the air velocity (Va) by an average of 0.75 m s-1 and a variation coefficient of 65%. The 1/gbv decreased significantly with the increase in Va, and the lowest value of 54.0 s m-1 was observed in T1. The low resistance to heat and moisture transfer enhanced the Sh and Lh of lettuce plants. The average Sh and Lh were 40% and 46% higher in T1 compared with those in T4. The fresh and dry weights of lettuce plants in T1 were 1.13 and 1.06 higher than those in T4, respectively. No tipburn occurrence was observed in lettuce plants grown under the MFS while five leaves per plant were injured with tipburn in T4. The results indicated that improving the airflow can improve the growth of indoor cultured lettuce and alleviate the occurrence of tipburn due to the decrease in the 1/gbv and the increase in the transpiration rate.

Addressing the impact of different fetal bovine serum percentages on mesenchymal stem cells biological performance.

Human mesenchymal stem cells (MSCs) are presently on the top of hierarchy in the field of stem cell therapy, due to their miraculous therapeutic abilities in diminishing the symptoms of many chronic diseases and initiating regeneration and repair for various damaged tissues and organs. The foremost initial step to reach high success rate in any MSCs based study is the optimization of culture growth media by establishing a suitable fetal bovine serum (FBS) percentage that suits the purpose of MSCs based experiment. Choosing the suitable FBS percentage is a controversial issue and merely depends on the researchers experience and suggested recommendations by the suppliers. Despite the huge improvements in overall MSCs investigating approaches, there are no definite protocols that set up a range of FBS percentages that can be followed. Toward achieving this objective, we evaluate in the present report the effect of using various FBS percentages (5-20%) added to DMEM low glucose media, on the biological behaviour of MSCs. Growing MSCs in high FBS percentages containing culture media (15% and 20% FBS) increase the proliferation and expansion rate of MSCs, although it decreases the immunosuppressive properties. On the other hand, adding low FBS percentage (7% FBS) to MSCs culture media enhanced the immunosuppression characteristics of MSCs, even though the proliferation rate was moderately reduced. 7% FBS is the cut off percentage that can be used without negatively altering major MSCs biological properties in which using 5% FBS will cause a tremendous decrease in the proliferation capacity and immunosuppressive properties. This report may assist other researchers in choosing appropriate FBS percentage when preparing MSCs culture media that serve the purpose of their MSCs based studies.

Impact of polymorphism on the optoelectronic properties of a low-bandgap semiconducting polymer.

Polymorphism of organic semiconducting materials exerts critical effects on their physical properties such as optical absorption, emission and electrical conductivity, and provides an excellent platform for investigating structure-property relations. It is, however, challenging to efficiently tune the polymorphism of conjugated polymers in aggregated, semi-crystalline phases due to their conformational freedom and anisotropic nature. Here, two distinctly different semi-crystalline polymorphs (ß1 and ß2) of a low-bandgap diketopyrrolopyrrole polymer are formed through controlling the solvent quality, as evidenced by spectroscopic, structural, thermal and charge transport studies. Compared to ß1, the ß2 polymorph exhibits a lower optical band gap, an enhanced photoluminescence, a reduced π-stacking distance, a higher hole mobility in field-effect transistors and improved photocurrent generation in polymer solar cells. The ß1 and ß2 polymorphs provide insights into the control of polymer self-organization for plastic electronics and hold potential for developing programmable ink formulations for next-generation electronic devices.

Anterior maxillary sandwich osteotomy technique with simultaneous implant placement: A novel approach for management of vertical deficiency.

BACKGROUND: The introduction of sandwich osteotomy technique with simultaneous implant placement allowed various procedures to be carried out with a level of great precision and accuracy thus saving time for the patient and clinician. PURPOSE: The aim of the current study is to evaluate the efficacy of this new technique regarding increasing the anterior maxillary alveolar height with simultaneous implant placement. MATERIALS AND METHODS: Nine patients suffering from multiple missing anterior maxillary teeth were selected with vertical dimension not less than 10 mm. anterior maxillary sandwich osteotomy technique was carried out for all patients using xenograft bone particulate with simultaneous implant placement at single stage surgery. RESULTS: For two patients, four implants showed significant marginal bone loss with maximum marginal bone loss up to 2.8 mm. However, the immediate postoperative follow up went uneventful for all nine patients included in the present study. None of them showed any complication regarding postoperative wound dehiscence, infection, or segment mobility. Four months postoperative upon the prosthetic phase, all the 18 placed implant were clinically osseointegtated. CONCLUSION: All 18 implants were successfully integrated in the present study. The prosthetic phase started after 4 months for all cases and there was no need for harvesting of autogenous bone from the patient. But further studies are required to evaluate the viability of such approach in single implant placement cases.

Recent predictive parameters for successful weaning from mechanical ventilation in critically Ill patients

Background: Removal of patients from mechanical ventilation (MV) has been termed liberation, discontinuation, withdrawal and most commonly weaning. Weaning covers the entire process of liberating the patient from mechanical support and from the endotracheal tube. Although weaning from MV is successful in most cases, the first attempt fails in 20% of patients. In addition, weaning accounts for over 40% of the total MV time, the proportion varying in function of the etiology of respiratory failure. Objective: The aim of this study was to evaluate the recent protocols of successful weaning from mechanical ventilation of critically ill patients, depending on central venous oxygen saturation, ultrasonographic assessment of diaphragmatic movement, and serial arterial blood gases to assess failure rate 48 hours after weaning. Patients and methods: This prospective randomized study included a total of 90 mechanically ventilated Egyptian patients of both sexes, ASA (I-II) attending at least for 48 hours at intensive care unit, AlAzhar University Hospitals. The included subjects were divided into three groups depending on method of monitoring; group A: serial arterial blood gases, group B: Central venous oxygen saturation and group C: Ultrasonographic assessment of diaphragmatic movement pre and post spontaneous breathing trial. All patients were subjected to daily monitoring of the following weaning parameters: static and dynamic compliances and inspiratory resistance, intrinsic positive end expiratory pressure (Auto PEEP) and Maximum inspiratory pressure (MIP). Results: There is highly statistically significant difference between patients as regard weaning outcome. As the group depended on normal ultrasonographic assessment of diaphragmatic movement, had the largest number of patients with successful weaning. Conclusion: Normal ultrasonographic assessment of diaphragmatic movement proved to be the most important criteria for successful weaning from mechanical ventilation

Does No-Touch Technique Better than Conventional or Intermediate Saphenous Vein Harvest Techniques for Coronary Artery Bypass Graft Surgery: a Systematic Review and Meta-analysis.

Saphenous vein (SV) is a common graft being used in coronary artery bypass grafting (CABG). Conventional (CON), intermediate (I), and no-touch (NT) are the most common harvesting techniques of SV for CABG. The aim of this study is to systematically review the NT versus CON and I techniques in harvesting SV for CABG. Twelve databases were searched for randomized controlled trials comparing the CON, I, and NT techniques in harvesting SV for CABG. Twelve reports of six RCTs were included. Our meta-analysis showed that with NT technique, patency rate was significantly higher when compared to I technique up to 18-month follow-up duration. In contrast, this significant difference was not maintained in terms of minor complications of leg wounds with both techniques. The NT has significantly higher patency rate compared to I vein harvesting technique. However, more RCTs are warranted to confirm these results.

Impact of dietary solvents on flexural properties of bulk-fill composites.

OBJECTIVE: This study investigated the effect of dietary solvents on flexural strength and modulus of bulk-fill composites. MATERIALS AND METHODS: One conventional composite (Filtek Z350 [FZ]), two bulk-fill composites (Filtek Bulk-fill [FB] and Tetric N Ceram [TN]) and a bulk-fill giomer (Beautifil-Bulk Restorative [BB]) were evaluated. Specimens (12 × 2 × 2 mm) were fabricated using customized stainless steel molds. Specimens were light-cured, removed from their molds, finished, measured and randomly divided into six groups. The groups (n = 10) were conditioned in the following mediums for 7 days at 37 °C: air (control), artificial saliva (SAGF), distilled water, 0.02 N citric acid, heptane, 50% ethanol-water solution. After conditioning, the specimens were rinsed, blotted dry, measured and subjected to flexural testing using a universal testing machine. Representative SEM images of the intact surfaces were obtained to appraise the degradation mechanism by dietary solvents. Data was subjected to statistical analysis using ANOVA/Tukey's tests at significance level p < 0.05. RESULTS: Significant differences in flexural properties were observed between materials and conditioning mediums. The highest flexural properties were usually obtained with conditioning in air (control) or heptane. Exposure to aqueous solutions generally reduced flexural properties of bulk-fill composites. CONCLUSION: The effect of dietary solvents on flexural properties of bulk-fill composites was material and medium dependent.

Application of a systematic approach to evaluating psychometric properties of a cumulative exit-from-degree objective structured clinical examination (OSCE).

BACKGROUND AND PURPOSE: Objective structured clinical examinations (OSCEs) are considered gold standard performance-based assessments yet comprehensive evaluation data is currently lacking. The objective of this study was to critically evaluate the psychometric properties of a cumulative OSCE for graduating pharmacy students in Qatar for which policies and procedures were adapted from a Canadian context. EDUCATIONAL ACTIVITY AND SETTING: A 10-station OSCE was conducted for graduating students in Qatar. Evaluation included assessment of pass rates, predictive validity, concurrent validity, internal validity, content validity, interrater reliability, and internal consistency. FINDINGS: Twenty-six students completed the OSCE. Three stations achieved pass rates < 80%. Scores from professional skills and case-based learning courses, formative OSCEs, and cumulative grade point averages correlated with OSCE scores (p < 0.05). Average correlation between assessors' analytical and global scoring was moderate (r = 0.52). Average interrater reliability was excellent for analytical scoring (ICC = 0.88) and moderate for global scoring (ICC = 0.61). Excellent internal consistency was demonstrated for overall performance (α = 0.927). Students generally agreed stations represented real practice scenarios (range per station, 30-100%). DISCUSSION AND SUMMARY: The evaluation model identified strengths and weaknesses in assessment and curricular considerations. The OSCE demonstrated acceptable validity and reliability as an adapted assessment.

Performance limitations in thieno[3,4-c]pyrrole-4,6-dione-based polymer:ITIC solar cells.

We report a systematic study of the efficiency limitations of non-fullerene organic solar cells that exhibit a small energy loss (Eloss) between the polymer donor and the non-fullerene acceptor. To clarify the impact of Eloss on the performance of the solar cells, three thieno[3,4-c]pyrrole-4,6-dione-based conjugated polymers (PTPD3T, PTPD2T, and PTPDBDT) are employed as the electron donor, which all have complementary absorption spectra compared with the ITIC acceptor. The corresponding photovoltaic devices show that low Eloss (0.54 eV) in PTPDBDT:ITIC leads to a high open-circuit voltage (Voc) of 1.05 V, but also to a small quantum efficiency, and in turn photocurrent. The high Voc or small energy loss in the PTPDBDT-based solar cells is a consequence of less non-radiative recombination, whereas the low quantum efficiency is attributed to the unfavorable micro-phase separation, as confirmed by the steady-state and time-resolved photoluminescence experiments, grazing-incidence wide-angle X-ray scattering, and resonant soft X-ray scattering (R-SoXS) measurements. We conclude that to achieve high performance non-fullerene solar cells, it is essential to realize a large Voc with small Eloss while simultaneously maintaining a high quantum efficiency by manipulating the molecular interaction in the bulk-heterojunction.

Dynamic analysis of bulk-fill composites: Effect of food-simulating liquids.

This study investigated the effect of food simulating liquids on visco-elastic properties of bulk-fill restoratives using dynamic mechanical analysis. One conventional composite (Filtek Z350 [FZ]), two bulk-fill composites (Filtek Bulk-fill [FB] and Tetric N Ceram [TN]) and a bulk-fill giomer (Beautifil-Bulk Restorative [BB]) were evaluated. Specimens (12 × 2 × 2mm) were fabricated using customized stainless steel molds. The specimens were light-cured, removed from their molds, finished, measured and randomly divided into six groups. The groups (n = 10) were conditioned in the following mediums for 7 days at 37°C: air (control), artificial saliva (SAGF), distilled water, 0.02N citric acid, heptane, 50% ethanol-water solution. Specimens were assessed using dynamic mechanical testing in flexural three-point bending mode and their respective mediums at 37°C and a frequency range of 0.1-10Hz. The distance between the supports were fixed at 10mm and an axial load of 5N was employed. Data for elastic modulus, viscous modulus and loss tangent were subjected to ANOVA/Tukey's tests at significance level p < 0.05. Significant differences in visco-elastic properties were observed between materials and mediums. Apart from bulk-fill giomer, elastic modulus was the highest after conditioning in heptane. No apparent trends were noted for viscous modulus. Generally, loss tangent was the highest after conditioning in ethanol. The effect of food-simulating liquids on the visco-elastic properties of bulk-fill composites was material and medium dependent.

Hybrid organic-inorganic inks flatten the energy landscape in colloidal quantum dot solids.

Bandtail states in disordered semiconductor materials result in losses in open-circuit voltage (Voc) and inhibit carrier transport in photovoltaics. For colloidal quantum dot (CQD) films that promise low-cost, large-area, air-stable photovoltaics, bandtails are determined by CQD synthetic polydispersity and inhomogeneous aggregation during the ligand-exchange process. Here we introduce a new method for the synthesis of solution-phase ligand-exchanged CQD inks that enable a flat energy landscape and an advantageously high packing density. In the solid state, these materials exhibit a sharper bandtail and reduced energy funnelling compared with the previous best CQD thin films for photovoltaics. Consequently, we demonstrate solar cells with higher Voc and more efficient charge injection into the electron acceptor, allowing the use of a closer-to-optimum bandgap to absorb more light. These enable the fabrication of CQD solar cells made via a solution-phase ligand exchange, with a certified power conversion efficiency of 11.28%. The devices are stable when stored in air, unencapsulated, for over 1,000 h.

Live/real time three-dimensional transesophageal echocardiographic assessment of the spinal cord.

We present an adult patient in whom live/real time three-dimensional transesophageal echocardiography (3DTEE) provided incremental value in the assessment of the spinal cord as compared to two-dimensional transesophageal echocardiographic (2DTEE) findings published in the literature. It improved accurate identification and assessment of the anterior radiculomedullary spinal arteries which may have an important clinical application in monitoring for spinal cord ischemia during thoracic aortic surgery. Because the spinal cord and spinal canal could be examined using not only transverse but also coronal (frontal), sagittal, and oblique planes, 3DTEE further allowed for three-dimensional measurements of the dimensions and volumetric analysis of the visualized spinal cord and spinal canal. These may have implications in the assessment of spinal cord edema due to trauma and other conditions which result in increase in the size and volume of the spinal cord.