Perovskite-polymer composite cross-linker approach for highly-stable and efficient perovskite solar cells.

Manipulation of grain boundaries in polycrystalline perovskite is an essential consideration for both the optoelectronic properties and environmental stability of solar cells as the solution-processing of perovskite films inevitably introduces many defects at grain boundaries. Though small molecule-based additives have proven to be effective defect passivating agents, their high volatility and diffusivity cannot render perovskite films robust enough against harsh environments. Here we suggest design rules for effective molecules by considering their molecular structure. From these, we introduce a strategy to form macromolecular intermediate phases using long chain polymers, which leads to the formation of a polymer-perovskite composite cross-linker. The cross-linker functions to bridge the perovskite grains, minimizing grain-to-grain electrical decoupling and yielding excellent environmental stability against moisture, light, and heat, which has not been attainable with small molecule defect passivating agents. Consequently, all photovoltaic parameters are significantly enhanced in the solar cells and the devices also show excellent stability

2D perovskite stabilized phase-pure formamidinium perovskite solar cells.

Compositional engineering has been used to overcome difficulties in fabricating high-quality phase-pure formamidinium perovskite films together with its ambient instability. However, this comes alongside an undesirable increase in bandgap that sacrifices the device photocurrent. Here we report the fabrication of phase-pure formamidinium-lead tri-iodide perovskite films with excellent optoelectronic quality and stability. Incorporation of 1.67 mol% of 2D phenylethylammonium lead iodide into the precursor solution enables the formation of phase-pure formamidinium perovskite with an order of magnitude enhanced photoluminescence lifetime. The 2D perovskite spontaneously forms at grain boundaries to protect the formamidinium perovskite from moisture and suppress ion migration. A stabilized power conversion efficiency (PCE) of 20.64% (certified stabilized PCE of 19.77%) is achieved with a short-circuit current density exceeding 24 mA cm-2 and an open-circuit voltage of 1.130 V, corresponding to a loss-in-potential of 0.35 V, and significantly enhanced operational stability

In Vivo Imaging of Schistosomes to Assess Disease Burden Using Positron Emission Tomography (PET)

Schistosomiasis is a well studied parasitic disease that is far from eradication despite the development of an effective treatment. The lack of an efficacious vaccine and high re-infection rates after treatment are major factors in its intractable worldwide prevalence. A non-invasive imaging technique like positron emission tomography (PET) could give clinicians and researchers a quantitative and visual tool to characterize the worm burden in infected individuals, determine the efficacy of a candidate vaccine, and provide information about parasite migration patterns and basic biology. We are therefore proposing the novel application of PET imaging to schistosomiasis in order to advance the management and research of this infectious disease. Herein, we demonstrate that schistosome parasites take up 2-deoxy-2[18F]fluoro-D-glucose (FDG). FDG uptake in regions adjacent to or within the liver linearly correlate with the worm number in infected mice, but the correlation was stronger in mice with high infection burdens. We anticipate that this research is a first step in the development of more specific radiotracers optimized for schistosomiasis, and will eventually translate to human studies

Boosting Heterosubtypic Neutralization Antibodies in Recipients of 2009 Pandemic H1N1 Influenza Vaccine

Our data demonstrated that the inoculation with vaccine derived from the 2009 pandemic influenza raised vigorous neutralization antibodies against both cognate H1N1 and heterotypic influenza viruses. This observation has important implication for vaccine development

Clinical oncologic applications of PET/MRI: a new horizon

Abstract: Positron emission tomography/magnetic resonance imaging (PET/MRI) leverages the high soft-tissue contrast and the functional sequences of MR with the molecular information of PET in one single, hybrid imaging technology. This technology, which was recently introduced into the clinical arena in a few medical centers worldwide, provides information about tumor biology and microenvironment. Studies on indirect PET/MRI (use of positron emission tomography/computed tomography (PET/CT) images software fused with MRI images) have already generated interesting preliminary data to pave the ground for potential applications of PET/MRI. These initial data convey that PET/MRI is promising in neuro-oncology and head & neck cancer applications as well as neoplasms in the abdomen and pelvis. The pediatric and young adult oncology population requiring frequent follow-up studies as well as pregnant woman might benefit from PET/MRI due to its lower ionizing radiation dose. The indication and planning of therapeutic interventions and specifically radiation therapy in individual patients could be and to a certain extent are already facilitated by performing PET/MRI. The objective of this article is to discuss potential clinical oncology indications of PET/MRI

Intrinsically Tuning the Electromechanical Properties of Elastomeric Dielectrics:A Chemistry Perspective

Dielectric elastomers have the capability to be used as transducers for actuation and energy harvesting applications due to their excellent combination of large strain capability (100–400%), rapid response (10−3 s), high energy density (10–150 kJ m−3), low noise, and lightweight nature. However, the dielectric properties of non‐polar elastomers such as dielectric permittivity ε r , breakdown strength E b , and dielectric loss ε ″, need to be enhanced for real world applications. The introduction of polar groups or structures into dielectric elastomers through covalently bonding is an attractive approach to ‘intrinsically’ induce a permanent polarity to the elastomers, and can eliminate the poor post‐processing issues and breakdown strength of extrinsically modified materials, which have often been prepared by incorporation of fillers. This review discusses the chemical methods for modification of dielectric elastomers, such as hydrosilylation, thiol‐ene click chemistry, azide click chemistry, and atom transfer radical polymerization. The effects of the type and concentration of polar groups on the dielectric and mechanical properties of the elastomers and their performance in actuation and harvesting systems are discussed. State‐of‐the‐art developments and perspectives of modified dielectric elastomers for deformable energy generators and transducers are provided

Issues pertaining to PET imaging of liver cancer

Positron emission tomography (PET) imaging using 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) has proven valuable in the diagnosis, staging and restaging for many cancers. However, its application for liver cancer has remained limited owing in part to the relatively high background uptake of the tracer in the liver plus the significant variability of the tumor specific uptake in liver cancer among patients. Thus, for primarily liver cancer, in particular, hepatocellular carcinoma (HCC), radio-tracers with better tumor-enhancing uptake/retention are still sought in order to harness the great power of PET imaging. Here, we reviewed some recent investigations with lipid-based small molecule PET radio-tracers with relevance to fasting, and discuss their potential in the diagnosis and staging of HCCs

A novel cache architecture with enhanced performance and security

Abstract—Caches ideally should have low miss rates and short access times, and should be power efficient at the same time. Such design goals are often contradictory in practice. Recent findings on efficient attacks based on information leakage in caches have also brought the security issue up front. Design for security introduces even more restrictions and typically leads to significant performance degradation. This paper presents a novel cache architecture that can simultaneously achieve the above goals. Specifically, cache miss rates are reduced with dynamic remapping and longer cache indices, access-time overhead overcome with astute low-level circuit design, and information leakage thwarted by a security-aware cache replacement algorithm together with the performance enhancing mechanisms. We present both theoretical analysis and experimental results, using the SPEC2000 suite to evaluate the cache miss behavior, and CACTI and HSPICE to validate the circuit design. Our results show that the proposed cache architecture has low miss rates comparable to a highly associative cache and short access times and power efficiency close to that of a direct-mapped cache. At the same time it can thwart cache-based software side-channel attacks, providing both legacy and security-enhanced software a much higher degree of security. Additional benefits that the proposed cache architecture can bring, like fault tolerance and hot-spot mitigation, are also discussed briefly. Keywords- cache; computer architecture; security; side channel attacks; performance I