Geomechanics for Energy and a Sustainable Environment

This book describes recent advances in geomechanics for energy and the sustainable environment. Four research articles, related to high-level radioactive nuclear waste disposal stability, geological effect and wellbore stability considerations for methane gas hydrate production, and artificial soil freezing, are presented in this book. In addition, a comprehensive state-of-the-art review verifies the strong correlation between global climate change and the occurrence of geotechnical engineering hazards. The review also summarizes recent attempts to reduce CO2 emissions from civil and geotechnical engineering practices. Readers will gain ideas as to how we can deal with conventional and renewable energy sources and environment-related geotechnical engineering issues

Application of Microbial Biopolymers as an Alternative Construction Binder for Earth Buildings in Underdeveloped Countries

Earth buildings are still a common type of residence for one-third of the world’s population. However, these buildings are not durable or resistant against earthquakes and floods, and this amplifies their potential harm to humans. Earthen construction without soil binders (e.g., cement) is known to result in poor strength and durability performance of earth buildings. Failure to use construction binders is related to the imbalance in binder prices in different countries. In particular, the price of cement in Africa, Middle East, and Southwest Asia countries is extremely high relative to the global trend of consumer goods and accounts for the limited usage of cement in those regions. Moreover, environmental concerns regarding cement usage have recently risen due to high CO2 emissions. Meanwhile, biopolymers have been introduced as an alternative binder for soil strengthening. Previous studies and feasibility attempts in this area show that the mechanical properties (i.e., compressive strength) of biopolymer mixed soil blocks (i.e, both 1% xanthan gum and 1% gellan gum) satisfied the international criteria for binders used in earthen structures. Economic and market analyses have demonstrated that the biopolymer binder has high potential as a self-sufficient local construction binder for earth buildings where the usage of ordinary cement is restricted

Debris flow mitigation by using biopolymers as a soil stabilizer

Towards rising the attention to the use of green materials in geotechnical applications, this study aims to introduce carrageenan as a new environment-friendly polymer for slope surface stabilization. A set of experiments were conducted to evaluate the performance of the biopolymer-treated soil to form a resistant surface against the surface erosion and debris flow. samples were tested by changing a variety of effective parameters including biopolymer content, moisture content, curing time, soil type, and durability under wet- dry cycles. Kaolinite soil along with river sand in different combinations were employed and treated by various biopolymer proportions to optimize the biopolymer and soil parameters. Subsequently, the optimum mixture of each biopolymer-treated soil was subjected to 5 cycles of wetting and drying. A broad microstructural study by performing FTIR analysis and scanning electron microscopy (SEM) images was conducted and an analytical model was developed to clarify how biopolymer stabilize the slope surface. The results confirm the successful performance of carrageenan in connecting soil grains, increasing mechanical strength and durability of soil against surface erosion. It can be concluded that carrageenan can be considered as a sustainable alternative to conventional materials such as cement and lime

Controlling Josephson transport by manipulation of Andreev levels in ballistic mesoscopic junctions

We discuss how to control dc Josephson current by influencing the structure and nonequilibrium population of Andreev levels via external electrostatic gates, external current injection and electromagnetic radiation. In particular we will consider the "giant" Josephson current in "long" SIS tunnel junctions and the regular and anomalous nonequilibrium Josephson currents in three terminal SNS junctions. We will briefly discuss applications to the Josephson field effect transistor (JOFET) and to the newly invented Josephson interference transistor (JOINT).Comment: 10 pages, 3 figures; contribution to a special volume of Superlattices and Microstructures journal (ed. P.F. Bagwell

Nonequilibrium Josephson effect in mesoscopic ballistic multiterminal SNS junctions

We present a detailed study of nonequilibrium Josephson currents and conductance in ballistic multiterminal SNS-devices. Nonequilibrium is created by means of quasiparticle injection from a normal reservoir connected to the normal part of the junction. By applying a voltage at the normal reservoir the Josephson current can be suppressed or the direction of the current can be reversed. For a junction longer than the thermal length, $L\gg\xi_T$, the nonequilibrium current increases linearly with applied voltage, saturating at a value equal to the equilibrium current of a short junction. The conductance exhibits a finite bias anomaly around $eV \sim \hbar v_F/L$. For symmetric injection, the conductance oscillates $2\pi$-periodically with the phase difference $\phi$ between the superconductors, with position of the minimum ($\phi=0$ or $\pi$) dependent on applied voltage and temperature. For asymmetric injection, both the nonequilibrium Josephson current and the conductance becomes $\pi$-periodic in phase difference. Inclusion of barriers at the NS-interfaces gives rise to a resonant behavior of the total Josephson current with respect to junction length with a period $\sim \lambda_F$. Both three and four terminal junctions are studied.Comment: 21 pages, 19 figures, submitted to Phys. Rev.

Institutional investors and corporate governance

We provide a comprehensive overview of the role of institutional investors in corporate governance with three main components. First, we establish new stylized facts documenting the evolution and importance of institutional ownership. Second, we provide a detailed characterization of key aspects of the legal and regulatory setting within which institutional investors govern portfolio firms. Third, we synthesize the evolving response of the recent theoretical and empirical academic literature in finance to the emergence of institutional investors in corporate governance. We highlight how the defining aspect of institutional investors – the fact that they are financial intermediaries – differentiates them in their governance role from standard principal blockholders. Further, not all institutional investors are identical, and we pay close attention to heterogeneity amongst institutional investors as blockholders

Graphene and Related Materials for Resistive Random Access Memories

Graphene and related materials (GRMs) are promising candidates for the fabrication of resistive random access memories (RRAM). Here, we analyze, classify and evaluate this emerging field, and summarize the performance of the RRAM prototypes using GRMs. Graphene oxide, amorphous carbon films, transition metal dichalcogenides, hexagonal boron nitride and black phosphorous can be used as resistive switching media, in which the switching can be governed either by the migration of intrinsic species or penetration of metallic ions from adjacent layers. Graphene can be used as electrode to provide flexibility and transparency, as well as an interface layer between the electrode and dielectric to block atomic diffusion, reduce power consumption, suppress surface effects, limit the number of conductive filaments in the dielectric, and improve device integration. GRMs-based RRAMs fit some non-volatile memory technological requirements like low operating voltages 10 years, endurance >109 cycles and power consumption ~10 pJ/transition still remain a challenge. More technology-oriented studies including reliability and variability analyses may lead to the development of GRMs-based RRAMs with realistic possibilities of commercialization.We acknowledge support from the Young 1000 Global Talent Recruitment Program of the Ministry of Education of China, the National Natural Science Foundation of China (grants no. 61502326, 41550110223), the Jiangsu Government (grant no. BK20150343), the Ministry of Finance of China (grant no. SX21400213), the Young 973 National Program of the Chinese Ministry of Science and Technology (grant no. 2015CB932700), the Collaborative Innovation Center of Suzhou Nano Science & Technology, the Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, the Priority Academic Program Development of Jiangsu Higher Education Institutions, the National Natural Science Foundation of China under Grant Nos. 61521064, 61322408, 61422407, the Beijing Training Project for the Leading Talents in S&T under Grant No. ljrc201508, the Opening Project of Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, the EU Graphene Flagship, FP7 Grant CARERAMM, ERC Grants Hetero2D and Highgraink, EPSRC Grants EP/K01711X/1, EP/K017144/1, EP/N010345/1, EP/M507799/1, EP/L016087/1, EP/M013243/1

International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS