Quantum nonlinear optics with single photons enabled by strongly interacting atoms

The realization of strong nonlinear interactions between individual light quanta (photons) is a long-standing goal in optical science and engineering, being of both fundamental and technological significance. In conventional optical materials, the nonlinearity at light powers corresponding to single photons is negligibly weak. Here we demonstrate a medium that is nonlinear at the level of individual quanta, exhibiting strong absorption of photon pairs while remaining transparent to single photons. The quantum nonlinearity is obtained by coherently coupling slowly propagating photons to strongly interacting atomic Rydberg states in a cold, dense atomic gas. Our approach paves the way for quantum-by-quantum control of light fields, including single-photon switching, all-optical deterministic quantum logic and the realization of strongly correlated many-body states of light.National Science Foundation (U.S.)MIT-Harvard Center for Ultracold AtomsUnited States. Air Force Office of Scientific Research. Multidisciplinary University Research Initiative (Quantum Memories

Microbial fuel cells: From fundamentals to applications. A review

© 2017 The Author(s) In the past 10–15 years, the microbial fuel cell (MFC) technology has captured the attention of the scientific community for the possibility of transforming organic waste directly into electricity through microbially catalyzed anodic, and microbial/enzymatic/abiotic cathodic electrochemical reactions. In this review, several aspects of the technology are considered. Firstly, a brief history of abiotic to biological fuel cells and subsequently, microbial fuel cells is presented. Secondly, the development of the concept of microbial fuel cell into a wider range of derivative technologies, called bioelectrochemical systems, is described introducing briefly microbial electrolysis cells, microbial desalination cells and microbial electrosynthesis cells. The focus is then shifted to electroactive biofilms and electron transfer mechanisms involved with solid electrodes. Carbonaceous and metallic anode materials are then introduced, followed by an explanation of the electro catalysis of the oxygen reduction reaction and its behavior in neutral media, from recent studies. Cathode catalysts based on carbonaceous, platinum-group metal and platinum-group-metal-free materials are presented, along with membrane materials with a view to future directions. Finally, microbial fuel cell practical implementation, through the utilization of energy output for practical applications, is described

Estimating population birth rates of zooplankton when rates of egg deposition and hatching are periodic

I present a general method of computing finite birth and death rates of natural zooplankton populations from changes in the age distribution of eggs and changes in population size. The method is applicable to cases in which eggs hatch periodically owing to variable rates of oviposition. When morphological criteria are used to determine the age distribution of eggs at the beginning and end of a sampling interval, egg mortality can be incorporated in estimates of population birth rate. I raised laboratory populations of Asplanchna priodonta , a common planktonic rotifer, in semicontinuous culture to evaluate my method of computing finite birth rate. The Asplanchna population became synchronized to a daily addition of food but grew by the same amount each day once steady state was achieved. The steady-state rate of growth, which can be computed from the volume-specific dilution rate of the culture, was consistent with the finite birth rate predicted from the population's egg ratio and egg age distribution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47764/1/442_2004_Article_BF00410359.pd

Canine cancer immunotherapy studies: linking mouse and human

Despite recent major clinical breakthroughs in human cancer immunotherapy including the use of checkpoint inhibitors and engineered T cells, important challenges remain, including determining the sub-populations of patients who will respond and who will experience at times significant toxicities. Although advances in cancer immunotherapy depend on preclinical testing, the majority of in-vivo testing currently relies on genetically identical inbred mouse models which, while offering critical insights regarding efficacy and mechanism of action, also vastly underrepresent the heterogeneity and complex interplay of human immune cells and cancers. Additionally, laboratory mice uncommonly develop spontaneous tumors, are housed under specific-pathogen free conditions which markedly impacts immune development, and incompletely model key aspects of the tumor/immune microenvironment. The canine model represents a powerful tool in cancer immunotherapy research as an important link between murine models and human clinical studies. Dogs represent an attractive outbred combination of companion animals that experience spontaneous cancer development in the setting of an intact immune system. This allows for study of complex immune interactions during the course of treatment while also directly addressing long-term efficacy and toxicity of cancer immunotherapies. However, immune dissection requires access to robust and validated immune assays and reagents as well as appropriate numbers for statistical evaluation. Canine studies will need further optimization of these important mechanistic tools for this model to fulfill its promise as a model for immunotherapy. This review aims to discuss the canine model in the context of existing preclinical cancer immunotherapy models to evaluate both its advantages and limitations, as well as highlighting its growth as a powerful tool in the burgeoning field of both human and veterinary immunotherapy

Understanding the role of solvents on the morphological structure and Li-ion conductivity of poly(vinylidene fluoride)-based polymer electrolytes

Polymer-based solid-state electrolytes (SSEs) are promising candidates to enhance the performances of current lithium-ion batteries (LiBs), as they possess advantages of facile processing and flexibility over ceramic SSEs. However, polymer SSEs such as poly(ethylene oxide) (PEO) suffer from low ionic conductivity, a limited voltage stability window, and thermal stability. Poly(vinylidene fluoride) (PVDF)-based polymer electrolytes (PPEs) with lean solvent confinement provide improved ionic conductivity and outstanding chemical/electrochemical stability. In this study, we report the effects of different solvents on the morphological structure and ionic conductivity of PPEs. We demonstrate that solvents with relatively high boiling points (dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-Methyl-2-pyrrolidone (NMP), and dimethylacetamide (DMA)) can be trapped in PPEs, and they all have positive effects on the ionic conductivity. The ionic conductivity is related to the quantity of the trapped solvent; for a PPE with DMF retention of ∼20%, the ionic conductivity is about 0.1 mS cm-1. Increasing the amount of lithium salt was found to improve the solvent retention but at the cost of membranes' mechanical property. It is also possible to introduce a low boiling point co-solvent in order to reduce the production cost and drying duration for manufacturing PPEs.</p

A 20 °C operating high capacity solid-state Li-S battery with an engineered carbon support cathode structure

A solid-state lithium-sulfur battery (SSLSB) exhibits much higher theoretical energy density compared with current intercalation electrode-based lithium-ion batteries (LiBs) and possesses excellent safety originated from the less flammable electrolyte. However, a small sulfur loading and limited utilization of active material hamper its practical application. Besides, an elevated temperature is usually required for the operation of SSLSBs. In the present work, a homogeneous nanostructured sulfur-Ketjen black (S@KB) composite cathode was synthesized through an energy-efficient deposition method. A stable and highly ionic conductive composite polymer-ceramic electrolyte (CPE) was employed as the solid-state electrolyte. The SSLSB delivered a pronounced specific capacity of 1108 mA h g−1 and areal capacity of 1.77 mA h cm−2, and demonstrated stable cycling for 50 cycles. Also, benefiting from fast reaction kinetics, the SSLSB was able to operate at 20 °C and established an excellent rate capability. These results emphasize the morphology control of the cathode plays a critical role in the electrochemical performance of SSLSBs.</p