Design Rules for Obtaining Narrow Luminescence from Semiconductors Made in Solution.

Solution-processed semiconductors are in demand for present and next-generation optoelectronic technologies ranging from displays to quantum light sources because of their scalability and ease of integration into devices with diverse form factors. One of the central requirements for semiconductors used in these applications is a narrow photoluminescence (PL) line width. Narrow emission line widths are needed to ensure both color and single-photon purity, raising the question of what design rules are needed to obtain narrow emission from semiconductors made in solution. In this review, we first examine the requirements for colloidal emitters for a variety of applications including light-emitting diodes, photodetectors, lasers, and quantum information science. Next, we will delve into the sources of spectral broadening, including "homogeneous" broadening from dynamical broadening mechanisms in single-particle spectra, heterogeneous broadening from static structural differences in ensemble spectra, and spectral diffusion. Then, we compare the current state of the art in terms of emission line width for a variety of colloidal materials including II-VI quantum dots (QDs) and nanoplatelets, III-V QDs, alloyed QDs, metal-halide perovskites including nanocrystals and 2D structures, doped nanocrystals, and, finally, as a point of comparison, organic molecules. We end with some conclusions and connections, including an outline of promising paths forward.

Standard versus low-dose computed tomography for assessment of acetabular fracture reduction using novel step and gap measurement technique.

PURPOSE: Quality of reduction is of paramount importance after acetabular fracture and is best assessed on computed tomography (CT). A recently proposed measurement technique for assessment of step and gap displacement is reproducible but has not been validated. The purpose of this study is to validate a well-established measurement technique against known displacements and to determine if it can be used with low dose CT. METHODS: Posterior wall acetabular fractures were created in 8 cadaveric hips and fixed at known step and gap displacements. CT was performed at multiple radiation doses for each hip. Four surgeons measured step and gap displacement for each hip at all doses, and the measurements were compared to known values. RESULTS: There were no significant differences in measurements across surgeons, and all measurements were found to have positive agreement. Measurement error < 1.5 mm was present in 58% of gap measurements and 46% of step measurements. Only for step measurements at a dose of 120 kVp did we observe a statistically significant measurement error. There was a significant difference in step measurements made by those with greater and those with fewer years in practice. CONCLUSION: Our study suggests this technique is valid and accurate across all doses. This is important as it may reduce the amount of radiation exposure for patients with acetabular fractures.

Plasmonic Response of Complex Nanoparticle Assemblies.

Optical properties of nanoparticle assemblies reflect distinctive characteristics of their building blocks and spatial organization, giving rise to emergent phenomena. Integrated experimental and computational studies have established design principles connecting the structure to properties for assembled clusters and superlattices. However, conventional electromagnetic simulations are too computationally expensive to treat more complex assemblies. Here we establish a fast, materials agnostic method to simulate the optical response of large nanoparticle assemblies incorporating both structural and compositional complexity. This many-bodied, mutual polarization method resolves limitations of established approaches, achieving rapid, accurate convergence for configurations including thousands of nanoparticles, with some overlapping. We demonstrate these capabilities by reproducing experimental trends and uncovering far- and near-field mechanisms governing the optical response of plasmonic semiconductor nanocrystal assemblies including structurally complex gel networks and compositionally complex mixed binary superlattices. This broadly applicable framework will facilitate the design of complex, hierarchically structured, and dynamic assemblies for desired optical characteristics.

Highly Responsive Plasmon Modulation in Dopant-Segregated Nanocrystals.

Electron transfer to and from metal oxide nanocrystals (NCs) modulates their infrared localized surface plasmon resonance (LSPR), revealing fundamental aspects of their photophysics and enabling dynamic optical applications. We synthesized and chemically reduced dopant-segregated Sn-doped In2O3 NCs, investigating the influence of radial dopant segregation on LSPR modulation and near-field enhancement (NFE). We found that core-doped NCs show large LSPR shifts and NFE change during chemical titration, enabling broadband modulation in LSPR energy of over 1000 cm-1 and of peak extinction over 300%. Simulations reveal that the evolution of the LSPR spectra during chemical reduction results from raising the surface Fermi level and increasing the donor defect density in the shell region. These results establish dopant segregation as a useful strategy to engineer the dynamic optical modulation in plasmonic semiconductor NC heterostructures going beyond what is possible with conventional plasmonic metals.

Best Current Practice and Research Priorities in Active Surveillance for Prostate Cancer-A Report of a Movember International Consensus Meeting.

BACKGROUND: Active surveillance (AS) is recommended for low-risk and some intermediate-risk prostate cancer. Uptake and practice of AS vary significantly across different settings, as does the experience of surveillance-from which tests are offered, and to the levels of psychological support. OBJECTIVE: To explore the current best practice and determine the most important research priorities in AS for prostate cancer. DESIGN, SETTING, AND PARTICIPANTS: A formal consensus process was followed, with an international expert panel of purposively sampled participants across a range of health care professionals and researchers, and those with lived experience of prostate cancer. Statements regarding the practice of AS and potential research priorities spanning the patient journey from surveillance to initiating treatment were developed. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Panel members scored each statement on a Likert scale. The group median score and measure of consensus were presented to participants prior to discussion and rescoring at panel meetings. Current best practice and future research priorities were identified, agreed upon, and finally ranked by panel members. RESULTS AND LIMITATIONS: There was consensus agreement that best practice includes the use of high-quality magnetic resonance imaging (MRI), which allows digital rectal examination (DRE) to be omitted, that repeat standard biopsy can be omitted when MRI and prostate-specific antigen (PSA) kinetics are stable, and that changes in PSA or DRE should prompt MRI ± biopsy rather than immediate active treatment. The highest ranked research priority was a dynamic, risk-adjusted AS approach, reducing testing for those at the least risk of progression. Improving the tests used in surveillance, ensuring equity of access and experience across different patients and settings, and improving information and communication between and within clinicians and patients were also high priorities. Limitations include the use of a limited number of panel members for practical reasons. CONCLUSIONS: The current best practice in AS includes the use of high-quality MRI to avoid DRE and as the first assessment for changes in PSA, with omission of repeat standard biopsy when PSA and MRI are stable. Development of a robust, dynamic, risk-adapted approach to surveillance is the highest research priority in AS for prostate cancer. PATIENT SUMMARY: A diverse group of experts in active surveillance, including a broad range of health care professionals and researchers and those with lived experience of prostate cancer, agreed that best practice includes the use of high-quality magnetic resonance imaging, which can allow digital rectal examination and some biopsies to be omitted. The highest research priority in active surveillance research was identified as the development of a dynamic, risk-adjusted approach.

Contact Conductance Governs Metallicity in Conducting Metal Oxide Nanocrystal Films.

Although colloidal nanoparticles hold promise for fabricating electronic components, the properties of nanoparticle-derived materials can be unpredictable. Materials made from metallic nanocrystals exhibit a variety of transport behavior ranging from insulators, with internanocrystal contacts acting as electron transport bottlenecks, to conventional metals, where phonon scattering limits electron mobility. The insulator-metal transition (IMT) in nanocrystal films is thought to be determined by contact conductance. Meanwhile, criteria are lacking to predict the characteristic transport behavior of metallic nanocrystal films beyond this threshold. Using a library of transparent conducting tin-doped indium oxide nanocrystal films with varied electron concentration, size, and contact area, we assess the IMT as it depends on contact conductance and show how contact conductance is also key to predicting the temperature-dependence of conductivity in metallic films. The results establish a phase diagram for electron transport behavior that can guide the creation of metallic conducting materials from nanocrystal building blocks.

Radiographic detection of lateral plateau involvement in medial tibial plateau fractures (AO/OTA 41-B1.2, 1.3, 3.2 and 3.3).

PURPOSE: To assess the accuracy of radiographs in detecting the lateral plateau involvement of medial tibial plateau fractures as well as describe the impact of CT on preoperative planning for this specific fracture morphology. METHODS: Radiograph and CT imaging of patients with a Schatzker type IV tibial plateau fractures (AO/OTA 41-B1.2, B1.3 h, B2.2. B3.2, and B3.3) between January 2013 and July 2017 were reviewed by three trauma fellowship-trained orthopedic surgeons to identify fractures of the medial condyle with an intact anterolateral articular surface. RESULTS: Lateral plateau involvement was identified in 16 (37%) radiographs and 26 (61%) CT images (p = 0.051). Radiographic detection of lateral plateau involvement demonstrated a sensitivity of 62% and specificity of 100%, and radiographs were able to predict the recommendation for surgical intervention for lateral plateau involvement with a positive predictive value (PPV) of 75% and a negative predictive value (NPV) of 60% compared to recommendations based on CT imaging. Radiographs predicted a need for a separate surgical approach with PPV of 63% and NPV of 70% when compared to recommendations based on CT images. CONCLUSIONS: Radiographs are reliable in ruling in lateral plateau involvement of medial plateau fractures, but occult lateral articular extension may only be identified in CT imaging for some cases. Surgical planning may be impacted by CT imaging for this fracture morphology, but further study is warranted to evaluate the correlation between preoperative planning and clinical outcomes. LEVEL OF EVIDENCE: III.

Nonoperative Treatment of Select Lateral Compression Type II Pelvic Ring Injuries (OTA/AO 61B2.2) Results in a Low Rate of Radiographic Displacement.

OBJECTIVES: To quantify radiographic outcomes and to identify predictors of late displacement in the nonoperative treatment of lateral compression type II (LC-2) pelvic ring injuries. DESIGN: Retrospective review. SETTING: Two Level 1 trauma centers. PATIENTS/PARTICIPANTS: Thirty eight patients 18 years of age or older with LC-2 pelvic ring injuries were included in the study. INTERVENTION: Nonoperative treatment. MAIN OUTCOME MEASUREMENTS: Crescent fracture displacement (CFD) was measured on initial axial computed tomography scan. Change in pelvic ring alignment was measured by the deformity index, simple ratio, and inlet and outlet ratios on successive plain radiographs. RESULTS: Patients in this study had minimally displaced LC-2 pelvic ring injuries, with median initial CFD of 2 mm and median initial deformity index of 2%. No patients had a change of more than or equal to 10 percentage points in deformity index over the treatment period, but small amounts of displacement were seen on the other ratios. No patients initially selected for nonoperative treatment converted to operative treatment. No radiographic predictors of late displacement were identified. Bilateral pubic rami fractures and the presence of a complete sacral fracture ipsilateral to the crescent fracture were not associated with late displacement. CONCLUSIONS: A spectrum of injury severity and stability exists in the LC-2 pattern. Nonoperative treatment of LC-2 injuries with low initial deformity and CFD results in minimal subsequent displacement. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Dual-Mode Infrared Absorption by Segregating Dopants within Plasmonic Semiconductor Nanocrystals.

When aliovalent dopants are sufficiently segregated to the core or near the surface of semiconductor nanocrystals, charge carriers donated by the dopants are also segregated to the core or near the surface, respectively. In Sn-doped indium oxide nanocrystals, we find that this contrast in free charge carrier concentration creates a core and shell with differing dielectric properties and results in two distinctly observable plasmonic extinction peaks. The trends in this dual-mode optical response with shell growth differ from core/shell nanoparticles composed of traditional plasmonic metals such as Au and Ag. We developed a model employing a core/shell effective medium approximation that can fit the dual-mode spectra and explain the trends in the extinction response. Lastly, we show that dopant segregation can improve sensitivity of plasmon spectra to changes in refractive index of the surrounding environment.

Standard Versus Low-Dose Computed Tomography for Assessment of Acetabular Fracture Reduction.

OBJECTIVE: First, to assess the impact of varying computed tomography (CT) radiation dose on surgeon assessment of postfixation acetabular fracture reduction and malpositioned implants. Second, to quantify the accuracy of CT assessments compared with the experimentally set displacement in cadaver specimens. We hypothesized that a CT dose would not affect the assessments and that CT assessments would show a high concordance with known displacement. METHODS: We created posterior wall acetabular fractures in 8 fresh-frozen cadaver hips and reduced them with varying combinations of step and gap displacement. The insertion of an intra-articular screw was randomized. Each specimen had a CT with standard (120 kV), intermediate (100 kV), and low-dose (80 kV) protocols, with and without metal artifact reduction postprocessing. Reviewers quantified gap and step displacement, overall reduction, quality of the scan, and identified intra-articular implants. RESULTS: There were no significant differences between the CT dose protocols for assessment of gap, step, overall displacement, or the presence of intra-articular screws. Reviewers correctly categorized displacement as anatomic (0-1 mm), imperfect (2-3 mm), or poor (>3 mm) in 27.5%-57.5% of specimens. When the anatomic and imperfect categories were condensed into a single category, these scores improved to 52.5%-82.5%. Intra-articular screws were correctly identified in 56.3% of cases. Interobserver reliability was poor or moderate for all items. Reviewers rated the quality of most scans as "sufficient" (60.0%-72.5%); reviewers more frequently rated the low-dose CT as "inferior" (30.0%) and the standard dose CT as "excellent" (25%). CONCLUSION: A CT dose did not affect assessment of displacement, intra-articular screw penetration, or subjective rating of scan quality in the setting of a fixed posterior wall fracture.

Quantitative Analysis of Extinction Coefficients of Tin-Doped Indium Oxide Nanocrystal Ensembles.

The optical extinction coefficients of localized surface plasmon resonance (LSPR) in doped semiconductor nanocrystals (NCs) have intensities determined by the density and damping mechanisms of free charge carriers. We investigate the dependence of the extinction coefficient of tin-doped indium oxide (ITO) NCs on size and dopant concentration and find extinction coefficients as high as 56.6 µm-1 in the near-infrared for 20 nm diameter ITO NCs with 7.5 atomic% Sn. We find ITO NCs to be more efficient infrared light absorbers than metal nanoparticles or molecular dyes. We also find the intensive, volume-normalized extinction coefficient increases significantly with NC doping and NC diameter, but only up to the point of saturation in both cases. We qualitatively analyze trends in LSPR peak position and width to explain the effect of doping and size on extinction.

Surface Depletion Layers in Plasmonic Metal Oxide Nanocrystals.

Strong infrared (IR) light-matter interaction and spectral tunability combine to make plasmonic metal oxide nanocrystals (NCs) a compelling choice for IR applications. In particular, visible transparency paired with strong, dynamically tunable IR absorption has motivated their implementation in electrochromic smart windows, but these NCs hold promise for a far broader range of plasmonically driven processes such as surface-enhanced infrared sensing, photothermal therapy, and enhanced photocatalysis. These unique properties result from localized surface plasmon resonance (LSPR) sustained by a relatively low free charge carrier concentration, which in turn requires consideration of distinct materials physics relative to traditional plasmonic materials (i.e., metals). Particularly important is the formation of insulating shells devoid of charge carriers (depletion layers) near the NC surface. Surface states as well as applied surface potentials can give rise to a potential difference between the NC surface and its core that depletes free charge carriers from the surface, forming an insulating shell that reduces the conductivity in NC films, lowers the dielectric sensitivity of the LSPR, and diminishes the incident electric field enhancement. In this Account, we report recent investigations of depletion layers in plasmonic metal oxide NCs that have advanced understanding of the semiconductor physics underlying the optoelectronic properties of these NCs and the electrochemical modulation of their LSPR, establishing a conceptual framework with which to broaden their applicability and optimize their performance. As a result of surface depletion, larger, highly doped NCs have improved dielectric sensitivity compared with their smaller, lightly doped counterparts. Concentrating dopants near the NC surface compresses the depletion layer, resulting in improved conductivity of NC films. Moreover, atomic layer deposition of alumina to infill NC films enhances the film conductivity by more than 2 orders of magnitude, ascribed to the elimination of depletion effects by reactive removal of surface water species. At the conclusion, we reflect on how our newfound understanding of surface depletion in plasmonic metal oxide NCs is quickly leading to rational material design. This insight is already resulting in significant performance improvements, and the same principles can be applied to new, exciting opportunities in hot carrier extraction and resonant IR energy transduction.

Tuning Nanocrystal Surface Depletion by Controlling Dopant Distribution as a Route Toward Enhanced Film Conductivity.

Electron conduction through bare metal oxide nanocrystal (NC) films is hindered by surface depletion regions resulting from the presence of surface states. We control the radial dopant distribution in tin-doped indium oxide (ITO) NCs as a means to manipulate the NC depletion width. We find in films of ITO NCs of equal overall dopant concentration that those with dopant-enriched surfaces show decreased depletion width and increased conductivity. Variable temperature conductivity data show electron localization length increases and associated depletion width decreases monotonically with increased density of dopants near the NC surface. We calculate band profiles for NCs of differing radial dopant distributions and in agreement with variable temperature conductivity fits find NCs with dopant-enriched surfaces have narrower depletion widths and longer localization lengths than those with dopant-enriched cores. Following amelioration of NC surface depletion by atomic layer deposition of alumina, all films of equal overall dopant concentration have similar conductivity. Variable temperature conductivity measurements on alumina-capped films indicate all films behave as granular metals. Herein, we conclude that dopant-enriched surfaces decrease the near-surface depletion region, which directly increases the electron localization length and conductivity of NC films.

Surgical excision of a symptomatic congenital coracoclavicular joint.

The coracoclavicular joint is a rare anatomic variant that consists of an articulation between the conoid tubercle of the clavicle and the superior surface of the coracoid process of the scapula. The coracoclavicular joint is most often asymptomatic and is found incidentally. A symptomatic coracoclavicular joint is exceedingly rare, with only 17 cases reported from 1915 to 2009. Symptoms may include limited range of motion, paresthesia, and brachialgia with radiation to the ipsilateral extremity. In the case of symptomatic coracoclavicular joints for which treatment data are reported, the response to conservative management with rest, analgesics, and physical therapy has been poor. Operative management resulted in complete resolution of symptoms in most patients and symptomatic improvement in the rest. This article reports the case of a 63-year-old man who presented with chronic left anterior shoulder pain exacerbated by forward flexion and overhead activities. Radiographs and computed tomography scan of the affected shoulder showed a bony articulation between the clavicle and the coracoid process of the scapula. The patient did not achieve long-term relief through conservative measures and corticosteroid injections, so the joint was surgically excised by an open procedure. Intraoperative findings were significant for a fully formed synovial joint with a capsule articulating between the clavicle and the coracoid process. After resection, the patient had minimal residual pain, improved range of motion, and symptomatic improvement with activity. The current case provides further data that the coracoclavicular joint can be the cause of significant shoulder pain and can be treated successfully with total resection of the joint if symptoms do not improve with conservative non-operative measures.

Drosophila Tempura, a novel protein prenyltransferase α subunit, regulates notch signaling via Rab1 and Rab11.

Vesicular trafficking plays a key role in tuning the activity of Notch signaling. Here, we describe a novel and conserved Rab geranylgeranyltransferase (RabGGT)-α-like subunit that is required for Notch signaling-mediated lateral inhibition and cell fate determination of external sensory organs. This protein is encoded by tempura, and its loss affects the secretion of Scabrous and Delta, two proteins required for proper Notch signaling. We show that Tempura forms a heretofore uncharacterized RabGGT complex that geranylgeranylates Rab1 and Rab11. This geranylgeranylation is required for their proper subcellular localization. A partial dysfunction of Rab1 affects Scabrous and Delta in the secretory pathway. In addition, a partial loss Rab11 affects trafficking of Delta. In summary, Tempura functions as a new geranylgeranyltransferase that regulates the subcellular localization of Rab1 and Rab11, which in turn regulate trafficking of Scabrous and Delta, thereby affecting Notch signaling.

Magnetic resonance studies of laryngeal tumors implanted in nude mice: effect of treatment with bleomycin and electroporation.

Recently, a new type of cancer treatment has been introduced that combines pulsed electric fields (PEF) with anticancer drugs. The proposed mode of action is that PEF create transient pores in the membranes which allow entry of drugs into the cells. This method increases cytotoxicity of some anticancer drugs like bleomycin (BLM) by 2-3 orders of magnitude, which, in turn, reduces systemic drug dosage without decreasing efficacy. In the present study, magnetic resonance imaging (MRI) was used to determine changes in apparent water self-diffusion coefficients (ADC) and spin-lattice (T(1)) and spin-spin (T(2)) relaxation times that occur in an animal laryngeal tumor (HEp-2 cells) model with BLM delivered by PEF. A Bruker 14 Tesla (600 MHz) wide-bore spectrometer with micro-imaging capability was used to generate all the data. Mice carrying approximately 8 mm tumors were treated with several combinations of drug and PEF. All measurements were made on tumor samples excised from mice 24 and 48 hours after treatment with (i) saline, intratumor injection (i.t.), (ii) BLM, i.t., (iii) saline with PEF, and (iv) BLM, i.t., followed by PEF. Although T(1) does not differ between the controls (i, ii, and iii) and full treatment (iv) 6.72 +/- 0.20 s vs. 6.31 +/- 1.7 s, T(2) for (iv) at 24 hours is significantly different from the controls 52.4 +/- 0.91 ms vs. 46.5 +/- 1.54 ms. T(2) differences between treatment and controls disappear at 48 hours. ADC increases significantly from 24 to 48 hours (7.31 +/- 0.16 x 10(-6) to 8.28 +/- 0.28 x 10(-6) cm(2)/sec, p = 0.05). Longer T(2) values may reflect early apoptosis and tumor death when the tumor is structurally less dense. Higher ADC's, associated with the periphery of the tumors and the central region, may indicate loose structural organization and necrosis resulting from the combination treatment.

Axial development and radial non-uniformity of flow in packed columns.

Flow inhomogeneity and axial development in low-pressure chromatographic columns have been studied by magnetic resonance imaging velocimetry. The columns studied included (a) an 11.7-mm I.D. column packed with either 50 microm diameter porous polyacrylamide, or 99 or 780 microm diameter impermeable polystyrene beads, and (b) a 5-mm I.D. column commercially packed with 10 microm polymeric beads. The packing methods included gravity settling, slurry packing, ultrasonication, and dry packing with vibration. The magnetic resonance method used averaged apparent fluid velocity over both column cross-sections and fluid displacements greater than one particle diameter and hence permits assessment of macroscopic flow non-uniformities. The results confirm that now non-uniformities induced by the conical distributor of the 11.7-mm I.D. column or the presence of voids at the column entrance relax on a length scale of the column radius. All of the 11.7-mm I.D. columns examined exhibit near wall channeling within a few particle diameters of the wall. The origins of this behavior are demonstrated by imaging of the radial dependence of the local porosity for a column packed with 780 microm beads. Columns packed with the 99-microm beads exhibit reduced flow in a region extending from ten to three-to-five particle diameters from the wall. This velocity reduction is consistent with a reduced porosity of 0.35 in this region as compared to approximately 0.43 in the bulk of the column. Ultrasonicated and dry-packed columns exhibit enhanced flow in a region located between approximately eight and 20 particle diameters from the wall. This enhancement maybe caused by packing density inhomogeneity and/or particle size segregation caused by vibration during the packing process. No significant non-uniformities on length scales of 20 microm or greater were observed in the commercially packed column packed with 10 microm particles.