Fast Money, 'Portfolio Urbanism', and the Remaking of an Industrial District into a Global Asset

Since the 2008 global financial crisis, many U.S. central cities have seen a boom in commercial property development led by innovative adaptive reuse and "creative office" projects. These have promoted new office submarkets in novel areas such as industrial districts or corridors adjacent to traditional commercial centers, including South Lake Union in Seattle, Chelsea Market in New York, Seaport District in Boston, and Fulton Market in Chicago. This boom has been conventionally interpreted as the outcome of several trends, including the growing importance of the millennial workforce in the labor market as well as new economic sectors such as technology, advertising, and media. The rapid pace of development has caused planners in cities such as Chicago to re-evaluate old industrial districts, focusing on facilitating new forms of redevelopment by reshaping existing local land use regulations and providing a new spatial vision for the area. In this dissertation, I argue that conventional interpretations of the rise of these creative office districts miss the mechanisms and dynamics underlying the transformation of old industrial spaces at the current moment. Through a case study of the post-2008 transformation of Chicago's Fulton Market and West Loop districts, I examine the unique characteristics of recent physical and economic changes and link them to a process of financialization of industrial space

Recovery Improvement for Large-Area Tungsten Diselenide Gas Sensors

Semiconducting two-dimensional transition-metal dichalcogenides are considered promising gas-sensing materials because of their large surface-to-volume ratio, excellent electrical conductivity, and susceptible surfaces. However, enhancement of the recovery performance has not yet been intensively explored. In this study, a large-area uniform WSe₂ is synthesized for use in a high-performance semiconductor gas sensor. At room temperature, the WSe₂ gas sensor shows a significantly high response (4140%) to NO₂ compared to the use of NH₃, CO₂, and acetone. This paper demonstrates improved recovery of the WSe₂ gas sensor’s NO₂-sensing performance by utilizing external thermal energy. In addition, a novel strategy for improving the recovery of the WSe₂ gas sensor is realized by reacting NH₃ and adsorbed NO₂ on the surface of WSe₂: the NO₂ molecules are spontaneously desorbed, and the recovery time is dramatically decreased (85 min → 43 s). It is expected that the fast recovery of the WSe₂ gas sensor achieved here will be used to develop an environmental monitoring system platform

Effect of Al₂O₃ Deposition on Performance of Top-Gated Monolayer MoS₂‑Based Field Effect Transistor

Deposition of high-<i>k</i> dielectrics on two-dimensional MoS₂ is an important process for successful application of the transition-metal dichalcogenides in electronic devices. Here, we show the effect of H₂O reactant exposure on monolayer (1L) MoS₂ during atomic layer deposition (ALD) of Al₂O₃. The results showed that the ALD-Al₂O₃ caused degradation of the performance of 1L MoS₂ field effect transistors (FETs) owing to the formation of Mo–O bonding and trapping of H₂O molecules at the Al₂O₃/MoS₂ interface. Furthermore, we demonstrated that reduced duration of exposure to H₂O reactant and postdeposition annealing were essential to the enhancement of the performance of top-gated 1L MoS₂ FETs. The mobility and on/off current ratios were increased by factors of approximately 40 and 10³, respectively, with reduced duration of exposure to H₂O reactant and with postdeposition annealing

All-Solid-State Reduced Graphene Oxide Supercapacitor with Large Volumetric Capacitance and Ultralong Stability Prepared by Electrophoretic Deposition Method

Portable energy storage devices have gained special attention due to the growing demand for portable electronics. Herein, an all-solid-state supercapacitor is successfully fabricated based on a poly­(vinyl alcohol)-H₃PO₄ (PVA–H₃PO₄) polymer electrolyte and a reduced graphene oxide (RGO) membrane electrode prepared by electrophoretic deposition (EPD). The RGO electrode fabricated by EPD contains an in-plane layer-by-layer alignment and a moderate porosity that accommodate the electrolyte ions. The all-solid-state RGO supercapacitor is thoroughly tested to give high specific volumetric capacitance (108 F cm^–3) and excellent energy and power densities (7.5 Wh cm^–3 and 2.9 W cm^–3, respectively). In addition, the all-solid-state RGO supercapacitor exhibits an ultralong lifetime for as long as 180 days (335 000 cycles), which is an ultrahigh cycling capability for a solid-state supercapacitor. The RGO is also tested for being used as a transparent supercapacitor electrode demonstrating its possible use in various transparent optoelectronic devices. Due to the facile scale-up capability of the EPD process and RGO dispersion, the developed all-solid-state supercapacitor is highly applicable to large-area portable energy storage devices

Improvement of Gas-Sensing Performance of Large-Area Tungsten Disulfide Nanosheets by Surface Functionalization

Semiconducting two-dimensional (2D) transition metal dichalcogenides (TMDCs) are promising gas-sensing materials due to their large surface-to-volume ratio. However, their poor gas-sensing performance resulting from the low response, incomplete recovery, and insufficient selectivity hinders the realization of high-performance 2D TMDC gas sensors. Here, we demonstrate the improvement of gas-sensing performance of large-area tungsten disulfide (WS₂) nanosheets through surface functionalization using Ag nanowires (NWs). Large-area WS₂ nanosheets were synthesized through atomic layer deposition of WO₃ followed by sulfurization. The pristine WS₂ gas sensors exhibited a significant response to acetone and NO₂ but an incomplete recovery in the case of NO₂ sensing. After AgNW functionalization, the WS₂ gas sensor showed dramatically improved response (667%) and recovery upon NO₂ exposure. Our results establish that the proposed method is a promising strategy to improve 2D TMDC gas sensors

Tunable Exciton Dissociation and Luminescence Quantum Yield at a Wide Band Gap Nanocrystal/Quasi-Ordered Regioregular Polythiophene interface

A comprehensive understanding of the effect of polymer chain aggregation-induced molecular ordering and the resulting formation of lower excited energy structures in a conjugated polymer on exciton dissociation and recombination at the interface with a wide-bandgap semiconductor is provided through correlation between structural arrangement of the polymer chains and the consequent electrical and optoelectronic properties. A vertical diode-type photovoltaic test probe is combined with a field effect current modulating device and various spectroscopic techniques to isolate the interfacial properties from the bulk properties. Enhanced energy migration in the quasi-ordered (poly­(3-hexylthiophene)) (P3HT) film, processed through vibration-induced aggregation of polymer chains in solution state, is attributed to the presence of the aggregation-induced interchain species in which excitons are allowed to migrate through low barrier energy sites, enabling efficient iso-energetic charge transfer followed by the downhill energy transfer. We discovered that formation of nonemissive excitons that reduces the photoluminescence quantum yield in the P3HT film deactivates exciton dissociation at the donor (P3HT) close to the acceptor (ZnO) as well as in the P3HT far away from the ZnO. In other words, exciton deactivation in its film state arising from the quasi-ordered structural arrangement of polymer chains in solution is retained at the donor/acceptor interface as well as in the bulk P3HT. Effect of change in the highest occupied molecular orbital level and the resulting energy band bending at the P3HT/ZnO interface on exciton dissociation is also discussed in relation to the presence of vibration-induced aggregates in the P3HT film

Automated detection and classification of the proximal humerus fracture by using deep learning algorithm

<p>Background and purpose — We aimed to evaluate the ability of artificial intelligence (a deep learning algorithm) to detect and classify proximal humerus fractures using plain anteroposterior shoulder radiographs.</p> <p>Patients and methods — 1,891 images (1 image per person) of normal shoulders (n = 515) and 4 proximal humerus fracture types (greater tuberosity, 346; surgical neck, 514; 3-part, 269; 4-part, 247) classified by 3 specialists were evaluated. We trained a deep convolutional neural network (CNN) after augmentation of a training dataset. The ability of the CNN, as measured by top-1 accuracy, area under receiver operating characteristics curve (AUC), sensitivity/specificity, and Youden index, in comparison with humans (28 general physicians, 11 general orthopedists, and 19 orthopedists specialized in the shoulder) to detect and classify proximal humerus fractures was evaluated.</p> <p>Results — The CNN showed a high performance of 96% top-1 accuracy, 1.00 AUC, 0.99/0.97 sensitivity/specificity, and 0.97 Youden index for distinguishing normal shoulders from proximal humerus fractures. In addition, the CNN showed promising results with 65–86% top-1 accuracy, 0.90–0.98 AUC, 0.88/0.83–0.97/0.94 sensitivity/specificity, and 0.71–0.90 Youden index for classifying fracture type. When compared with the human groups, the CNN showed superior performance to that of general physicians and orthopedists, similar performance to orthopedists specialized in the shoulder, and the superior performance of the CNN was more marked in complex 3- and 4-part fractures.</p> <p>Interpretation — The use of artificial intelligence can accurately detect and classify proximal humerus fractures on plain shoulder AP radiographs. Further studies are necessary to determine the feasibility of applying artificial intelligence in the clinic and whether its use could improve care and outcomes compared with current orthopedic assessments.</p

Additive-Free Hollow-Structured Co₃O₄ Nanoparticle Li-Ion Battery: The Origins of Irreversible Capacity Loss

Origins of the irreversible capacity loss were addressed through probing changes in the electronic and structural properties of hollow-structured Co₃O₄ nanoparticles (NPs) during lithiation and delithiation using electrochemical Co₃O₄ transistor devices that function as a Co₃O₄ Li-ion battery. Additive-free Co₃O₄ NPs were assembled into a Li-ion battery, allowing us to isolate and explore the effects of the Co and Li₂O formation/decomposition conversion reactions on the electrical and structural degradation within Co₃O₄ NP films. NP films ranging between a single monolayer and multilayered film hundreds of nanometers thick prepared with blade-coating and electrophoretic deposition methods, respectively, were embedded in the transistor devices for <i>in situ</i> conduction measurements as a function of battery cycles. During battery operation, the electronic and structural properties of Co₃O₄ NP films in the bulk, Co₃O₄/electrolyte, and Co₃O₄/current collector interfaces were spatially mapped to address the origin of the initial irreversible capacity loss from the first lithiation process. Further, change in carrier injection/extraction between the current collector and the Co₃O₄ NPs was explored using a modified electrochemical transistor device with multiple voltage probes along the electrical channel

Competition between Charge Transport and Energy Barrier in Injection-Limited Metal/Quantum Dot Nanocrystal Contacts

Injection-limited contacts in many of electronic devices such as light-emitting diodes (LEDs) and field effect transistors (FETs) are not easily avoided. We demonstrate that charge injection in the injection-limited contact is determined by charge transport properties as well as the charge injection energy barrier due to vacuum energy level alignment. Interestingly, injection-limited contact properties were observed at 5 nm diameter lead sulfide (PbS) quantum dot (QD)/Au contacts for which carrier injection is predicted to be energetically favorable. To probe the effect of charge transport properties on carrier injection, the electrical channel resistance of PbS nanocrystal (NC) FETs was varied through thermal annealing, photoillumination, ligand exchange, surface treatment of the gate dielectric, and use of different sized PbS NCs. Injection current through the PbS/Au contact varied with the FET mobility of PbS NC films consistent with a theoretical prediction where the net injection current is dominated by carrier mobility. This result suggests that the charge transport properties, that is, mobility, of QD NC films should be considered as a means to enhance carrier injection along with the vacuum level energy alignment at the interface between QD NCs and metal electrodes. Photocurrent microscopic images of the PbS/Au contact demonstrate the presence of a built-in potential in a two-dimensionally continuous PbS film near the metal electrodes