bluuebunny/crossref_metadata_2025 huggingface dataset:
MicroRNA
s in Cancer
Authors: Munker Reinhold , Shackelford Rodney , Calin George A
Published: August 2016

Initially considered an epiphenomenon, micro ribonucleic acids (also called miRNAs) and other small noncoding RNA molecules are now considered major players in cell biology. MiRNAs regulate gene expression through effects on translation, transcription and chromatin modification. Multiple miRNAs are dysregulated in human cancer and affect cellular proliferation, apoptosis, metastasis and tumour invasion and the phenotype of cancer cells. Virtually every cell type and cancer has a specific miRNA expression pattern. This unique miRNA expression pattern allows the classification of specific cancer types and often gives prognostic information. Profiling based on miRNAs may be more specific and robust than profiling based on mRNAs. MiRNAs can be studied in virtually all tissues including plasma. More work is required, but miRNAs have already improved our understanding of the pathogenesis of cancer and tumour progression and appear promising as novel diagnostic biomarkers. Finally, they may be of value in the development of new genetic treatments.

Key Concepts

MicroRNAs regulate gene expression.

MicroRNAs are important in the pathogenesis and progression of human cancers.

MicroRNAs can function as tumour suppressors and as tumour promoters (oncomirs).

Cancers of different origin have specific microRNA expression patterns, allowing molecular characterisation.

MicroRNAs can serve as biomarkers for cancer and may become useful for the treatment of cancer.

MicroRNA analysis may give prognostic information and be of use in subtyping histologically similar tumours into less and more clinically aggressive categories.

Exosomes contain microRNAs and processing enzymes and mediate some of the biological effects of microRNAs.
Microbial Pathogen Effectors in Plant Disease
Authors: Pelgrom Alexandra JE , Van den Ackerveken Guido
Published: August 2016

Microbial plant pathogens use secreted effector proteins for successful infection of their host. This evolved state is rather exceptional as most microbes do not cause disease in the vast majority of plant species. An important primary activity of effectors is to interfere with a range of plant immune processes to evade and suppress pathogen detection, or to block immune signalling and downstream responses. Furthermore, effectors can enhance disease susceptibility by altering cellular processes and modulating host transcription. For most of these activities, effectors specifically target plant proteins that are central in these processes. An advanced virulence strategy is the post‐translational modification by effectors of plant targets to change their activity or stability. The knowledge gathered on the molecular mechanisms underlying effector‐triggered susceptibility of plants provides great potential for novel approaches of resistance breeding.

Key Concepts

Pathogens secrete and/or translocate effector proteins to promote plant disease.

Besides their primary role in promoting disease, effectors or effector‐modified plant proteins can be recognised by resistance proteins to activate an effector‐triggered immune response.

Many effectors block pathogen‐associated molecular pattern (PAMP)‐triggered immunity and/or effector‐triggered immunity.

Other effectors rewire signalling pathways and reprogramme the plant cell to promote pathogen growth.

Certain effectors can affect the activity or function of host proteins by post‐translational modifications e.g. (de)phosphorylation or targeting for proteosomal degradation.
Biofortification of Edible Crops
Authors: White Philip J
Published: August 2016

Humans require sufficient amounts of at least 18 mineral elements for normal development and well‐being. Unfortunately, many people's diets lack sufficient iron, zinc, calcium, magnesium, iodine and selenium. Mineral malnutrition can be addressed by dietary diversification, mineral supplementation, food fortification or the biofortification of edible crops. Biofortification can be achieved by two complementary strategies. The ‘genetic’ strategy, which includes breeding and genetic manipulation of crops, aims not only to increase the acquisition of mineral elements and their accumulation in edible portions but also to improve their bioavailability by altering concentrations affecting uptake by the gut. The ‘agronomic’ strategy, which includes effective soil management and fertiliser applications, aims to increase the phytoavailability of mineral elements. Using these strategies, staple crops can be adequately biofortified with minerals currently lacking in people's diets. Furthermore, biofortification appears to be a cost‐effective approach to alleviating mineral malnutrition, reaching urban and rural populations in developed and developing nations.

Key Concepts

Human diets must supply sufficient quantities of 18 essential mineral elements.

Many people's diets lack sufficient iron, zinc, calcium, magnesium, iodine or selenium.

One strategy to combat mineral malnutrition in humans is biofortification of edible crops.

Biofortification increases the bioavailable concentrations of essential minerals in produce.

Agronomic biofortification strategies include effective soil management and fertiliser applications.

Genetic biofortification strategies employ the selection, breeding or genetic manipulation of crops.

Crop genotypes can be developed with greater acquisition and accumulation of minerals in edible portions.

Crop genotypes can be developed with reduced concentrations of antinutrients, such as phytate or oxalate, or greater concentrations of promoter substances, such as ascorbate, β‐carotene, protein cysteine and various organic acids and amino acids, to improve the bioavailability of minerals.

Biofortification is a cost‐effective strategy to alleviate mineral malnutrition and can reach both urban and rural populations in developed and developing nations.
Conservation of Island Flora and Fauna
Authors: Cronk Quentin
Published: August 2016

Islands, especially small oceanic islands, are highly sensitive to the introduction of alien biota. As islands have often been stopovers in the early development of international trade, there have been many opportunities for the introduction of alien organisms. As island food webs are simple, the addition of species can destabilise them (trophic interference) causing the collapse of normal trophic interactions and potentially the extirpation of whole ecosystems. In St Helena the native ecosystems were largely destroyed by events set in train after human discovery of the island, particularly the introduction of the goat. Ecosystem repair is challenging: total eradication of invasives can be problematic. If total eradication is impossible, classical biological control is an alternative. Gene drive biological control is an emerging technology that may be used in future. One consequence of wholesale ecosystem destruction is that many island species are ‘ultra‐rare’ (reduced to total populations of 10 individuals or less). In such cases, inbreeding may have caused fitness problems compounding extinction risk. In such cases, genetic rescue may be required, via the deliberate beneficial increase of the allele pool from other populations or even other species via adaptive introgression.

Key Concepts

Island ecosytems are vulnerable to introduced species.

Terrestrial mamals do not disperse well and are absent from oceanic islands.

Introduced species, especially mammalian herbivores and carnivores, destabilise existing trophic structure (trophic interference) and can lead to the collapse of ecosystems.

Total eradication of invasives, or their biological control, can sometimes be possible to eliminate or mitigate the effect of invasives.
De Novo
Methylation in Cancer
Authors: Funata Sayaka , Fukayama Masashi , Kaneda Atsushi
Published: August 2016

Epigenetics is the mechanism of gene expression regulation, which does not change DNA (deoxyribonucleic acid) sequences. Once CpG dinucleotides at the promotor regions are methylated, downstream genes are repressed. This process is essential for normal development and differentiation and is involved in cancer pathogenesis. Many tumour‐suppressor genes are repressed by aberrant promotor methylation. In addition, clinical cancer cases are classified into distinct subgroups based on DNA methylation accumulation patterns, suggesting that there might be a characteristic pathway of tumorigenesis in each subgroup. For example, the high‐methylation subgroup of colorectal cancer arises from sessile serrated adenomas that show similar high‐methylation accumulation and
BRAF
mutation. In gastric tumorigenesis, infection of pathogens, for example,
Helicobacter pylori
and Epstein‐Barr virus, can induce
de novo
methylation in gastric epithelial cells. Advances in the knowledge of DNA methylation accumulation patterns and the causal event of methylation induction lead to understanding molecular tumorigenic mechanisms.

Key Concepts

DNA methylation is mediated by DNA methyltransferases (DNMTs).

DNA demethylation is mediated by Ten‐eleven‐translocation (TET) family enzymes.

Tumour‐suppressor genes are frequently hypermethylated and silenced in cancer.

Clinical cancer cases are classified into distinct subgroups based on DNA methylation accumulation patterns.

Chronic inflammation may induce DNA methylation into epithelial cells.

Epstein‐Barr virus infection can induce DNA methylation into host cells.

Disruption of TET function through mutation of
IDH
or
TET
genes can cause aberrant DNA methylation.

Aberrant methylation might be used for cancer diagnosis and treatment.
Importance of Mutation Analysis in Anti‐Cancer Therapy
Authors: Yu Bing
Published: August 2016

Advances in cancer genome research have led to a paradigm shift of anti‐cancer treatment from cytotoxic chemotherapy to targeted therapy. Mutation analysis plays an indispensable role in identifying actionable molecular events, predicting responses to targeted therapies and ensuring optimal treatment. It helps clinical decision making to achieve efficient and cost‐effective anti‐cancer treatment. Liquid biopsy is a less invasive but promising strategy for repeated mutation analyses in cancer patients since it provides temporal information that is tumour‐ and treatment‐specific. Liquid biopsy can provide diagnostic and prognostic information and has the potential to replace tissue biopsy. This information can be used to assess tumour heterogeneity, monitor tumour dynamics before, during and after treatment, detect minimal residual disease and recurrence and identify resistance to therapy. Mutation analysis has become an integral part of precision cancer medicine.

Key Concepts

Anti‐cancer therapy is moving from the morphology‐based ‘one‐size‐fits‐all’ strategy to mutation profile‐based ‘personalised medicine’.

Mutation analysis plays an indispensable role in the selection of the most suitable anti‐cancer therapies.

Comprehensive and rapid mutation profiling has a significant impact on precision and so helps avoid under‐treatment, ineffective therapy or over‐treatment.

Failure of anti‐cancer treatment reflects our inability to profile tumour diversity, monitor tumour evolution and adapt therapeutic strategies accordingly.

Liquid biopsy is a less invasive but promising strategy to obtain insights into therapy‐induced selection of cancer cells.

Temporal and dynamic information from repeated liquid biopsy can help clinical decision making in cancer management.
Gene and Cell Therapy for Inherited Retinal Dystrophies
Authors: Garita‐Hernandez Marcela , Goureau Olivier , Dalkara Deniz
Published: August 2016

Gene therapy and cell therapy are intersecting fields of biomedical research with the common aim of repairing the direct causes or consequences of genetic diseases by using genes and cells, respectively. Gene therapy is broadly defined as a set of strategies that modify the expression of an individual's genes for therapeutic benefit. It requires the administration of a specific deoxyribonucleic acid (DNA) (or ribonucleic acid (RNA)) into the patient's cells. Cell therapy on the other hand requires administration of a population of intact live cells to a patient whose cells have been lost due to injury or disease. These emerging strategies can also be applied in acquired diseases in order to re‐establish equilibrium and halt disease progression. In some cases, gene and cell therapy may be combined in order to obtain a therapeutic effect.

In addition to becoming emerging therapeutics in the clinic, these two fields of research continually generate tools, concepts and techniques for elucidating biological questions across multiple disciplines.

Key Concepts

The retina lines the back of the eye and comprises six different types of neuronal cells and their underlying retinal pigment epithelium (RPE).

Photoreceptors are the light‐sensitive first‐order neurons of the retina which capture the light stimulus and transform it into an electric signal.

Human iPSC have the same features of hESC in terms of their differentiation capacity.

Gene therapy is the use of genetic material as a drug to treat a chronic condition.
Assessment of Disease‐Associated Sequence Variants and Considerations for Functional Validation using Mouse Models
Authors: Cox Timothy C , Cox Liza L
Published: August 2016

Whole‐exome and whole‐genome sequencing approaches are rapidly becoming mainstream tools accessible to both basic researchers and clinical teams. Likewise, technological advances in genome editing, such as the CRISPR/Cas system, are poised to revolutionise model system research, making it more feasible to create animal models that truly recapitulate the human condition. However, procedures for identifying disease‐associated sequence variants are still far from robust and there are many biological variables that need to be considered when attempting to functionally validate disease‐associated variants. In this article, we highlight the many limitations and issues that should be considered at different stages throughout this process – from the filtering of sequencing data to the selection of variants, and from the selection of the model organism to the appropriate means of phenotyping.

Key Concepts

Researchers must appreciate the limitations of exome sequencing when considering candidate gene variants.

Researchers using sequencing services should ensure they receive the original BAM files of their sequencing data.

Common bioinformatic algorithms used to process sequencing data are predictive tools only.

Bioinformatic tools should not be used in isolation or their outputs taken as proof of disease causation of a variant.

Gene expression in a tissue consistent with that affected in patients can be used to help prioritise candidate genes but is not evidence for causation.

Demonstration of a functional impact of a given variant in anin vitroassay is useful but does not necessarily mean it is responsible for the disease of interest.

Genetic background of the mouse strain(s) can significantly influence the phenotypic presentation.

Researchers using animal models should consider the composition of animal chow when modelling a disease with considerable phenotypic variability.
Bioethics after
L
evinas
Authors: Goldim José R
Published: August 2016

Bioethics is not a new discipline; nor should it be understood as a mere evolution of medical ethics, or even as simply ethics applied to life. Bioethics seeks to find meaning and justification for old and new practices related to life and living. Alterity, proposed by Levinas, includes the Other in the individual's relationship with the world. The nature of this new relationship is dialogic, leading to mutual commitment and co‐responsibility. Recognising the Other prevents neutrality and furnishes the opening to the mystery of the relation to the Other. The Other is a singular being, always important and significant. The Other is the one who opens up the possibility of living, of establishing relationships that gives meaning to life. Levinas' thought emphasises acting, praxis, effective action and moment of decision.

Key Concepts

Bioethics is a complex, interdisciplinary and shared reflection on the adequacy of actions related to life and living.

Levinas' thought raises an important discussion on the issue of the difference between the Same and the Other.

Within the framework of Alterity, it is the Other who gives meaning to a person's own existence.

In Levinas' thought, acting is a priority, as are praxis, effective action and moment of decision.

Including the Other in the perspective of an individual's relationship with the world changes this view.
Bounded‐input iterative learning control: Robust stabilization via a minimax approach
Authors: Driessen Brian , Sadegh Nader , Kwok Kwan
Published: August 2016

In this paper, we consider the design problem of making the convergence of the bounded‐input, multi‐input iterative learning controller presented in our previous work robust to errors in the model‐based value of the input‐output Jacobian matrix via a minimax (min‐max or 'minimize the worst case') approach. We propose to minimize the worst case (largest) value of the infinity‐norm of the matrix whose norm being less then unity implies convergence of the controller. This matrix is the one associated with monotonicity of a sequence of input error norms. The input‐output Jacobian uncertainty is taken to be an additive linear one. Theorem 3.1 and its proof show that the worst‐case infinity‐norm is actually minimized by choosing either the inverse of the centroid of the set of possible input‐output Jacobians or a zero matrix. And an explicit expression is given for both the criteria used to choose between the two matrices and the resulting minimum worst‐case infinity norm. We showed previously that the matrix norm condition associated with monotonicity of a sequence of output‐error norms is not sufficient to assure convergence of the bounded‐input controller. The importance of knowing which norm condition is the relevant one is demonstrated by showing that the set of minimizers of the minimax problem formulated with the wrong norm does not contain in general minimizers of the maximum relevant norm and moreover can lead to a gain matrix that destroys the assured convergence of the bounded‐input controller given in previous work. Copyright © 2016 John Wiley & Sons, Ltd.
Hierarchical Graphene‐Based Films with Dynamic Self‐Stiffening for Biomimetic Artificial Muscle
Authors: Dai Zhaohe , Wang Yanlei , Liu Luqi , Liu Xuelu , Tan PingHeng , Xu Zhiping , Kuang Jun , Liu Qing , Lou Jun , Zhang Zhong
Published: August 2016

Biological tissues such as muscle cells can adapt their structural and mechanical response upon external mechanical stimuli. Conversely, artificial muscles, intended to reproduce the salient functional features of biological muscles, usually undergo mechanical fatigue when subjected to dynamic stress. Besides passively improving the resilience to dynamic loads, here, it is reported that macroscopic films based on graphene and its chemical derivate exhibit an increase in modulus by up to 84% after subjected to a low‐amplitude (0.1%) dynamic tension. Through a combination of experimental testing and molecular dynamics simulations, the unique self‐stiffening behavior is attributed to the straightening and reorientation of graphene sheets and is further tuned through tailoring interlayer adhesion. Meanwhile, artificial muscles based on graphene films are designed and interestingly improved stiffness of our muscle materials after “training” are demonstrated. These results help to harness the stiffening mechanism and can be useful for the development of adaptable structural materials for biomechanical applications.
Scissor‐Like Chiral Metamolecules for Probing Intracellular Telomerase Activity
Authors: Sun Maozhong , Xu Liguang , Fu Pan , Wu Xiaoling , Kuang Hua , Liu Liqiang , Xu Chuanlai
Published: August 2016

A DNA‐driven gold (Au) heterodimer for intracellular telomerase detection is fabricated. The highly biocompatible and intracellularly stable probe shows an active chiroptical property in the visible region, due to the scissor‐like configuration formed by prolate nanoparticles. Importantly, the telomerase activity is specifically quantified using circular dichroism intensity in situ after internalization of the heterodimer into cancer cells. Moreover, the results clearly illustrate that this method has a remarkable linear range from 0.8 × 10−12 to 32 × 10−12 IU, and the limit of detection for telomerase activity is 1.7 × 10−15 IU in a single HeLa cell. This strategy paves the way for chirality‐based ultrasensitive detection of intracellular cancer markers.
Composition and Structure of Oyster Adhesive Reveals Heterogeneous Materials Properties in a Biological Composite
Authors: Metzler Rebecca A. , Rist Rebecca , Alberts Erik , Kenny Paul , Wilker Jonathan J.
Published: August 2016

Oyster reefs help maintain coastal ecosystems by filtering water, holding silt in place, and absorbing storm surge energy. We are just beginning to understand the chemical and structural nature of the adhesive used by these animals for building such reef communities. The adhesive has a high calcium carbonate content relative to other bioadhesives, but also appreciable levels of organics, presumably for bonding. The studies presented here use X‐ray absorption near edge structure spectroscopy, X‐ray photoemission electron microscopy, scanning electron microscopy, and microhardness methods to understand the composition, as well as the mechanical properties, of this biological material. Oyster adhesive appears to be a heterogeneous mixture of calcium carbonate and silica inclusions arranged randomly within a matrix that lacks any observable structure. Microindentation shows inclusions are significantly harder than their surroundings. This hard plus soft strategy has been noted in other biological materials, although not in any adhesives. These compositional and structural insights help propose a mechanism by which the animals generate their adhesive. Such an intriguing structure, along with resulting mechanical implications, may help explain how oyster reefs can thrive despite being subjected to demanding forces created by predators and the environment around them.
Photoreduced Graphene Oxide as a Conductive Binder to Improve the Water Splitting Activity of Photocatalyst Sheets
Authors: Pan Zhenhua , Hisatomi Takashi , Wang Qian , Chen Shanshan , Iwase Akihide , Nakabayashi Mamiko , Shibata Naoya , Takata Tsuyoshi , Katayama Masao , Minegishi Tsutomu , Kudo Akihiko , Domen Kazunari
Published: August 2016

Photocatalyst sheets consisting of H2 evolution photocatalyst (HEP) and O2 evolution photocatalyst (OEP) particles applied to an underlying conductive layer show promise with regard to promoting efficient and scalable water splitting. One of the most important challenges in enhancing the performance of such systems is establishing efficient charge transfer between photocatalyst particles that are often thickly stacked on the conductive layer. In this study, reduced graphene oxide (RGO) is investigated as an additional solid mediator to the conductive layer to bridge particulate photocatalysts and thus ensure effective charge transfer. Photocatalyst sheets made of RhCrOx/LaMg1/3Ta2/3O2N as the HEP and BiVO4:Mo as the OEP are applied to an Au layer together with RGO. The activity of this system is 3.5 times greater following the incorporation of the RGO. Charaterization analyses reveal that RhCrOx/LaMg1/3Ta2/3O2N particles tens of nanometers in size are fixed on larger, micrometer‐sized, BiVO4:Mo particles by RGO photoreduced from GO in situ. The RGO facilitates charge transfer between particles that are distant from the underlying Au layer and thus involves more photocatalyst particles in the water splitting reaction. It is concluded that the incorporation of conductive materials into the photocatalyst particle layer can effectively enhance the water splitting activity of photocatalyst sheets.
Electric‐Field‐Controlled Alignment of Rod‐Shaped Fluorescent Nanocrystals in Smectic Liquid Crystal Defect Arrays
Authors: Gryn Iryna , Lacaze Emmanuelle , Carbone Luigi , Giocondo Michele , Zappone Bruno
Published: August 2016

Periodic micro‐arrays of straight linear defects containing nanoparticles can be created over large surface areas at the transition from the nematic to smectic‐A phase in a nanoparticle–liquid crystal (LC) composite material confined under the effect of conflicting anchoring conditions (unidirectional planar vs normal) and electric fields. Anisomeric dichroic dye molecules and rod‐shaped fluorescent semiconductor nanocrystals (dot‐in‐rods) with large permanent electric dipole and high linearly polarized photoluminescence quantum yield align parallel to the local LC molecular director and follow its reorientation under application of the electric field. In the nano‐sized core regions of linear defects, where the director is undefined, anisotropic particles align parallel to the defect whereas spherical quantum dots do not show any particular interaction with the defect. Under application of an electric field, ferroelectric semiconductor nanoparticles in the core region align along the field, perpendicular to the defect direction, whereas dichroic dyes remain parallel to the defect. This study provides useful insights into the complex interaction of anisotropic nanoparticles and anisotropic soft materials such as LCs in the presence of external fields, which may help the development of field‐responsive nanoparticle‐based functional materials.
Self‐Assembling Doxorubicin Prodrug Forming Nanoparticles and Effectively Reversing Drug Resistance In Vitro and In Vivo
Authors: Mao Xiaoman , Si Jingxing , Huang Qian , Sun Xuanrong , Zhang Qianzhi , Shen Youqing , Tang Jianbin , Liu Xiangrui , Sui Meihua
Published: August 2016

Doxorubicin (DOX) is a widely used chemotherapeutic drug to treat a range of cancers. However, its unfavorable effects, particularly the cardiotoxicity and the induction of multidrug resistance (MDR), significantly limit its clinical applications. Herein, a novel doxorubicin prodrug, PEG2K‐DOX, is synthesized by conjugating a deprotonated doxorubicin molecule with the polyethylene glycol (PEG, MW: 2K) chain via pH‐responsive hydrazone bond, and its potential as a better alternative than doxorubicin is evaluated. The data show that the amphiphilic PEG2K‐DOX can self‐assemble into stable nanoparticles with a high and fixed doxorubicin loading content (≈20 wt%), a favorable size of 91.5 nm with a narrow polydispersity (PDI = 0.14), good stability, and pH‐dependent release behavior due to the acid‐cleavable linkage between PEG and doxorubicin. Although doxorubicin hardly accumulates in MDR cells, PEG2K‐DOX nanoparticles significantly increase the cellular uptake and cell‐killing activity of doxorubicin in two MDR cancer cell lines MCF‐7/ADR and KBv200, with the IC50 values dropped to 1.130% and 42.467% of doxorubicin, respectively. More impressively, PEG2K‐DOX nanoparticles exhibit significantly improved plasma pharmacokinetics, increased in vivo therapeutic efficacy against MDR xenograft tumors, and better in vivo safety compared with doxorubicin. PEG2K‐DOX nanoparticles hold the promise to become a better alternative than doxorubicin for cancer treatment, especially for MDR tumors.
Water‐Dispersible Fluorescent Silicon Nanoparticles and their Optical Applications
Authors: Su Yuanyuan , Ji Xiaoyuan , He Yao
Published: August 2016

Fluorescent silicon nanoparticles (SiNPs) attract considerable attention owing to their intrinsic advantages, including relatively strong fluorescence coupled with robust photostability, rich resource support and relatively low cost, industrial maturity, and good biocompatibility. Extensive efforts are devoted to developing effective methods for the synthesis of hydrogen or halogen‐terminated SiNPs, which nevertheless need further surface modification to improve their stability and solubility for wide‐ranging applications. Notably, recent years have witnessed the development of various aqueous synthetic strategies for direct preparation of highly fluorescent and photostable SiNPs in the aqueous phase, facilitating the promotion of this promising material for myriad optical applications. Here, a concise discussion of the latest exciting research progress of the preparation of SiNPs is given, with a focus on water‐dispersible SiNPs synthesized in the aqueous phase. In addition, representative optical applications of SiNPs in bioimaging and sensing are also summarized. Finally, the opportunities and challenges of fluorescent‐SiNP‐based optical applications are discussed.
Soybean Oil‐Based Polyurethane–(Poly)acrylonitrile Interpenetrating Polymer Networks as Transparent Coating Materials
Authors: Das Subhajit , Kalita Hemjyoti , Mohanty Smita , Nayak Sanjay Kumar
Published: August 2016

In this study, soybean oil‐based polyurethane–(poly)acrylonitrile (PU–PAN) interpenetrating polymer networks (IPN) were synthesized by the reaction of soybean oil‐based polyol, isophorone diisocyanate, and acrylonitrile. The formation of IPN were confirmed by the FTIR and differential scanning calorimetry (DSC) studies. The mechanical properties such as tensile strength, Young's modulus, hardness, and abrasion resistance were found to be increased with the increase of PU content in the IPN. IPN showed higher thermal stability and lesser burning rate than PU. Surface morphology was observed by SEM and AFM studies. The IPN showed higher hydrophobic nature than PU, studied by contact angle measurement.
Metal–Organic Framework for Emulsifying Carbon Dioxide and Water
Authors: Liu Chengcheng , Zhang Jianling , Zheng Lirong , Zhang Jing , Sang Xinxin , Kang Xinchen , Zhang Bingxing , Luo Tian , Tan Xiuniang , Han Buxing
Published: August 2016

Forming emulsions of carbon dioxide (CO2) and water can largely expand the utility of CO2. Herein we propose for the first time the utilization of a metal–organic framework (MOF) for emulsifying CO2 and water. Owing to the hybrid composition, MOF particles can easily assemble at the CO2/water interface to create a rigid protective barrier around the dispersed droplet. The MOF‐stabilized CO2 and water emulsion has exceptional stability compared to those emulsions stabilized by surfactants or other solids. Moreover, the CO2 and water emulsion stabilized by MOF is “tunable” due to the designable features of MOFs and adjustable character of CO2. Such a novel kind of emulsion composed of CO2, water, and MOF provides a facile route for constructing MOF superstructures with many advantages. The macroporous networks and hollow capsules of different kinds of MOFs have been successfully derived from CO2 and water emulsions.
Highly Efficient Catalytic Formation of (Z)‐1,4‐But‐2‐ene Diols Using Water as a Nucleophile
Authors: Guo Wusheng , Martínez‐Rodríguez Luis , Martin Eddy , Escudero‐Adán Eduardo C. , Kleij Arjan W.
Published: August 2016

The first general catalytic and highly stereoselective formation of (Z)‐1,4‐but‐2‐ene diols is described from readily available and modular vinyl‐substituted cyclic carbonate precursors using water as a nucleophilic reagent. These 1,4‐diol scaffolds can be generally prepared in high yields and with ample scope in reaction partners using a simple synthetic method that does not require the presence of any additive or any special precaution unlike the stoichiometric approaches reported to date. Control experiments support the mechanistic view that hyperconjugation within the catalytic intermediate after decarboxylation plays an imperative role to control the stereoselective outcome of these reactions.
DNA Origami Rotaxanes: Tailored Synthesis and Controlled Structure Switching
Authors: Powell John T. , Akhuetie‐Oni Benjamin O. , Zhang Zhao , Lin Chenxiang
Published: August 2016

Mechanically interlocked supramolecular assemblies are appealing building blocks for creating functional nanodevices. Herein, we describe the multistep assembly of large DNA origami rotaxanes that are capable of programmable structural switching. We validated the topology and structural integrity of these rotaxanes by analyzing the intermediate and final products of various assembly routes by electrophoresis and electron microscopy. We further analyzed two structure‐switching behaviors of our rotaxanes, which are both mediated by DNA hybridization. In the first mechanism, the translational motion of the macrocycle can be triggered or halted at either terminus. In the second mechanism, the macrocycle can be elongated after completion of the rotaxane assembly, giving rise to a unique structure that is otherwise difficult to access.
Assembly of a Highly Stable Luminescent Zn5 Cluster and Application to Bio‐Imaging
Authors: Zeng Ming‐Hua , Yin Zheng , Liu Ze‐Hui , Xu Hai‐Bing , Feng Ying‐Chun , Hu Yue‐Qiao , Chang Li‐Xian , Zhang Yue‐Xing , Huang Jin , Kurmoo Mohamedally
Published: August 2016

The assembly sequence of the coordination cluster [Zn5(H2Ln)6](NO3)4]⋅8 H2O⋅2 CH3OH (Zn5, H3Ln=(1,2‐bis(benzo[d]imidazol‐2‐yl)‐ethenol) involves in situ dehydration of 1,2‐bis(benzo[d]imidazol‐2‐yl)‐1,2‐ethanediol (H4L) through the formation of the [Zn(H3L)2]+ monomer, dimerization to [Zn2(H3L)2]+, dehydration of the ligand to [Zn2(H2Ln)2]+, and the final formation of the pentanuclear cluster. The cluster has the following special characteristics: 1) high stability in both refluxing 37 % HCl and 27 % NH3, 2) low cytotoxicity, and 3) pH‐sensitive fluorescence in the visible‐to‐near‐infrared (Vis/NIR) region in the solid state and in solution. We have applied it as a fluorescent probe both in vivo and in vitro. Its H‐bonding ability is the key to its affinity and selectivity for imaging lysosomes in HeLa cells and tumors in male BALB/C mice. It provides a new type of sensitive and biocompatible fluorescent probe for detecting small tumors (13.5 mm3).
A Terminal Osmium(IV) Nitride: Ammonia Formation and Ambiphilic Reactivity
Authors: Schendzielorz Florian S. , Finger Markus , Volkmann Christian , Würtele Christian , Schneider Sven
Published: August 2016

Low‐valent osmium nitrides are discussed as intermediates in nitrogen fixation schemes. However, rational synthetic routes that lead to isolable examples are currently unknown. Here, the synthesis of the square‐planar osmium(IV) nitride [OsN(PNP)] (PNP=N(CH2CH2P(tBu)2)2) is reported upon reversible deprotonation of osmium(VI) hydride [Os(N)H(PNP)]+. The OsIV complex shows ambiphilic nitride reactivity with SiMe3Br and PMe3, respectively. Importantly, the hydrogenolysis with H2 gives ammonia and the polyhydride complex [OsH4(HPNP)] in 80 % yield. Hence, our results directly demonstrate the role of low‐valent osmium nitrides and of heterolytic H2 activation for ammonia synthesis with H2 under basic conditions.
Upregulation of an Artificial Zymogen by Proteolysis
Authors: Liu Zhe , Lebrun Vincent , Kitanosono Taku , Mallin Hendrik , Köhler Valentin , Häussinger Daniel , Hilvert Donald , Kobayashi Shu , Ward Thomas R.
Published: August 2016

Regulation of enzymatic activity is vital to living organisms. Here, we report the development and the genetic optimization of an artificial zymogen requiring the action of a natural protease to upregulate its latent asymmetric transfer hydrogenase activity.
Few‐Layer Antimonene by Liquid‐Phase Exfoliation
Authors: Gibaja Carlos , Rodriguez‐San‐Miguel David , Ares Pablo , Gómez‐Herrero Julio , Varela Maria , Gillen Roland , Maultzsch Janina , Hauke Frank , Hirsch Andreas , Abellán Gonzalo , Zamora Félix
Published: August 2016

We report on a fast and simple method to produce highly stable isopropanol/water (4:1) suspensions of few‐layer antimonene by liquid‐phase exfoliation of antimony crystals in a process that is assisted by sonication but does not require the addition of any surfactant. This straightforward method generates dispersions of few‐layer antimonene suitable for on‐surface isolation. Analysis by atomic force microscopy, scanning transmission electron microscopy, and electron energy loss spectroscopy confirmed the formation of high‐quality few‐layer antimonene nanosheets with large lateral dimensions. These nanolayers are extremely stable under ambient conditions. Their Raman signals are strongly thickness‐dependent, which was rationalized by means of density functional theory calculations.
Total Synthesis of the Diterpenoid (+)‐Harringtonolide
Authors: Zhang Hai‐Jun , Hu Lin , Ma Zhiqiang , Li Ruining , Zhang Zhen , Tao Cheng , Cheng Bin , Li Yun , Wang Huifei , Zhai Hongbin
Published: August 2016

Described herein is the first asymmetric total synthesis of (+)‐harringtonolide, a natural diterpenoid with an unusual tropone imbedded in a cagelike framework. The key transformations include an intramolecular Diels–Alder reaction and a rhodium‐complex‐catalyzed intramolecular [3+2] cycloaddition to install the tetracyclic core as well as a highly efficient tropone formation.
Multilayer Microcapsules for FRET Analysis and Two‐Photon‐Activated Photodynamic Therapy
Authors: Yang Yang , Liu Huiling , Han Mingjuan , Sun Bingbing , Li Junbai
Published: August 2016

Microcapsules obtained by layer‐by‐layer assembly provide a good platform for biological analysis owing to their component diversity, multiple binding sites, and controllable wall thickness. Herein, different assembly species were obtained from two‐photon dyes and traditional photosensitizers, and further assembled into microcapsules. Fluorescence resonance energy transfer (FRET) was shown to occur between the two‐photon dyes and photosensitizers. Confocal laser scanning microscopy (CLSM) with one‐ and two‐photon lasers, fluorescence lifetime imaging microscopy (FLIM), and time‐resolved fluorescence spectroscopy were used to analyze the FRET effects in the microcapsules. The FRET efficiency could easily be controlled through changing the assembly sequence. Furthermore, the capsules are phototoxic upon one‐ or two‐photon excitation. These materials are thus expected to be applicable in two‐photon‐activated photodynamic therapy for deep‐tissue treatment.
Efficient O‐Functionalization of Carbohydrates with Electrophilic Reagents
Authors: Tolnai Gergely L. , Nilsson Ulf J. , Olofsson Berit
Published: August 2016

Novel methodology for O‐functionalization of carbohydrate derivatives has been established using bench‐stable and easily prepared iodonium(III) reagents. Both electron‐withdrawing and electron‐donating aryl groups were introduced under ambient conditions and without precautions to exclude air or moisture. Furthermore, the approach was extended both to full arylation of cyclodextrin, and to trifluoroethylation of carbohydrate derivatives. This is the first general approach to introduce traditionally non‐electrophilic groups into any of the OH groups around the sugar backbone. The methodology will be useful both in synthetic organic chemistry and biochemistry, as important functional groups can be incorporated under simple and robust reaction conditions in a fast and efficient manner.
An Organocatalytic Cope Rearrangement
Authors: Kaldre Dainis , Gleason James L.
Published: August 2016

The first example of an organocatalytic Cope rearrangement is reported. Acyclic and cyclic acyl hydrazides catalyze the rearrangement of 1,5‐hexadiene‐2‐carboxaldehydes via iminium ion formation. A correlation between ring size and catalyst activity was observed for the cyclic hydrazides, with seven‐ and eight‐membered‐ring catalysts being the most active. Diazepane carboxylate 5 c (10 mol %) catalyzed the rearrangement of a range of dienes at room temperature in acetonitrile using triflic acid as a co‐catalyst. Preliminary proof of principle for asymmetric catalysis was provided by rearrangement of 3,3‐dimethyl‐7‐phenyl‐1,5‐heptadiene‐2‐carboxaldehyde in the presence of a novel 7‐substituted diazepane carboxylate.
Fluorescent Gold Nanoclusters with Interlocked Staples and a Fully Thiolate‐Bound Kernel
Authors: Gan Zibao , Lin Yuejian , Luo Lun , Han Guangmei , Liu Wei , Liu Zhengjie , Yao Chuanhao , Weng Linhong , Liao Lingwen , Chen Jishi , Liu Xu , Luo Yi , Wang Chengming , Wei Shiqiang , Wu Zhikun
Published: August 2016

The structural features that render gold nanoclusters intrinsically fluorescent are currently not well understood. To address this issue, highly fluorescent gold nanoclusters have to be synthesized, and their structures must be determined. We herein report the synthesis of three fluorescent Au24(SR)20 nanoclusters (R=C2H4Ph, CH2Ph, or CH2C6H4tBu). According to UV/Vis/NIR, differential pulse voltammetry (DPV), and X‐ray absorption fine structure (XAFS) analysis, these three nanoclusters adopt similar structures that feature a bi‐tetrahedral Au8 kernel protected by four tetrameric Au4(SR)5 motifs. At least two structural features are responsible for the unusual fluorescence of the Au24(SR)20 nanoclusters: Two pairs of interlocked Au4(SR)5 staples reduce the vibration loss, and the interactions between the kernel and the thiolate motifs enhance electron transfer from the ligand to the kernel moiety through the Au−S bonds, thereby enhancing the fluorescence. This work provides some clarification of the structure–fluorescence relationship of such clusters.
Formation of CoS2 Nanobubble Hollow Prisms for Highly Reversible Lithium Storage
Authors: Yu Le , Yang Jing Fan , Lou Xiong Wen (David)
Published: August 2016

Metal–organic frameworks (MOFs) have been intensively used as the templates/precursors to synthesize complex hollow structures for various energy‐related applications. Herein we report a facile two‐step diffusion‐controlled strategy to generate novel MOFs derived hierarchical hollow prisms composed of Nanosized CoS2 bubble‐like subunits. Uniform zeolitic imidazolate framework‐67 (ZIF‐67) hollow prisms assembled by interconnected nanopolyhedra are first synthesized via a transformation process. Afterwards, these ZIF‐67 building blocks are converted into CoS2 bubble‐like hollow particles to form the complex hollow prisms through a sulfidation reaction with an additional annealing treatment. When evaluated as an electrode material for lithium‐ion batteries, the as‐obtained CoS2 nanobubble hollow prisms show remarkable electrochemical performance with good rate capability and long cycle life.
A One‐Pot Chemically Cleavable Bis‐Linker Tether Strategy for the Synthesis of Heterodimeric Peptides
Authors: Patil Nitin A. , Tailhades Julien , Karas John A. , Separovic Frances , Wade John D. , Hossain Mohammed Akhter
Published: August 2016

Heterodimeric peptides linked by disulfide bonds are attractive drug targets. However, their chemical assembly can be tedious, time‐consuming, and low yielding. Inspired by the cellular synthesis of pro‐insulin in which the two constituent peptide chains are expressed as a single‐chain precursor separated by a connecting C‐peptide, we have developed a novel chemically cleavable bis‐linker tether which allows the convenient assembly of two peptide chains as a single “pro”‐peptide on the same solid support. Following the peptide cleavage and post‐synthetic modifications, this bis‐linker tether can be removed in one‐step by chemical means. This method was used to synthesize a drug delivery‐cargo conjugate, TAT‐PKCi peptide, and a two‐disulfide bridged heterodimeric peptide, thionin (7‐19)‐(24‐32R), a thionin analogue. To our knowledge, this is the first report of a one‐pot chemically cleavable bis‐linker strategy for the facile synthesis of cross‐bridged two‐chain peptides.
Bifunctional‐Phosphine‐Catalyzed Sequential Annulations of Allenoates and Ketimines: Construction of Functionalized Poly‐heterocycle Rings
Authors: Li Erqing , Jin Hongxing , Jia Penghao , Dong Xuelin , Huang You
Published: August 2016

A highly stereoselective sequential annulation reaction between γ‐substituted allenoates and ketimines was reported. By using bifunctional N‐acyl aminophosphine catalysts, poly‐heterocycle rings were obtained with high stereocontrol in good to excellent yields. The desired products have four contiguous stereogenic centers (one quaternary and three tertiary carbon centers), and only one isomer was obtained in all reactions.
Ground‐State Chemical Reactivity under Vibrational Coupling to the Vacuum Electromagnetic Field
Authors: Thomas Anoop , George Jino , Shalabney Atef , Dryzhakov Marian , Varma Sreejith J. , Moran Joseph , Chervy Thibault , Zhong Xiaolan , Devaux Eloïse , Genet Cyriaque , Hutchison James A. , Ebbesen Thomas W.
Published: August 2016

The ground‐state deprotection of a simple alkynylsilane is studied under vibrational strong coupling to the zero‐point fluctuations, or vacuum electromagnetic field, of a resonant IR microfluidic cavity. The reaction rate decreased by a factor of up to 5.5 when the Si−C vibrational stretching modes of the reactant were strongly coupled. The relative change in the reaction rate under strong coupling depends on the Rabi splitting energy. Product analysis by GC‐MS confirmed the kinetic results. Temperature dependence shows that the activation enthalpy and entropy change significantly, suggesting that the transition state is modified from an associative to a dissociative type. These findings show that vibrational strong coupling provides a powerful approach for modifying and controlling chemical landscapes and for understanding reaction mechanisms.
A Family of Multiply Bonded Dimolybdenum Boraamidinates with the Formal Mo−Mo Bond Orders of 3, 4, 4.5, and 5
Authors: Lu Duan‐Yen , Kuo Ting‐Shen , Tsai Yi‐Chou
Published: August 2016

A boraamidinato ligand [PhB(N‐2,6‐iPr2C6H3)2]2− was employed to stabilize a new family of multiply bonded dimolybdenum complexes [MoCl(μ‐κ2‐PhB(N‐2,6‐iPr2C6H3)2)]2 (4) and [Mo(μ‐κ2‐PhB(N‐2,6‐iPr2C6H3)2)]2n− (n=0 (5), 1 (6), 2 (7)), with the respective formal Mo−Mo bond orders of 3, 4, 4.5, and 5. Each metal center in 5–7 is two‐coordinate with respect to the ligands. Of particular interest is the quadruply bonded dimolybdenum complex 5, featuring an unprecedented angular conformation. The bent Mo2N4 core of 5 distorts toward planarity upon reduction. As a result, compound 7 features a planar Mo2N4 core, while that of 6 is still bent but less significantly than that of 5. Additionally, the Mo−Mo bond lengths of 4–7 systematically decrease as the valency of the central Mo2 units decreases. Complex 7 features the shortest Mo−Mo bond length (2.0106(5) Å) yet reported.
Direct Transformation of Molecular Dinitrogen into Ammonia Catalyzed by Cobalt Dinitrogen Complexes Bearing Anionic PNP Pincer Ligands
Authors: Kuriyama Shogo , Arashiba Kazuya , Tanaka Hiromasa , Matsuo Yuki , Nakajima Kazunari , Yoshizawa Kazunari , Nishibayashi Yoshiaki
Published: August 2016

The direct formation of ammonia from molecular dinitrogen under mild reaction conditions was achieved by using new cobalt dinitrogen complexes bearing an anionic PNP‐type pincer ligand. Up to 15.9 equivalents of ammonia were produced based on the amount of catalyst together with 1.0 equivalent of hydrazine (17.9 equiv of fixed nitrogen atoms).
Gold‐catalyzed Intermolecular Oxidations of 2‐Ketonyl‐1‐ethynyl Benzenes with N‐Hydoxyanilines to Yield 2‐Aminoindenones via Gold Carbene Intermediates
Authors: Mokar Bhanudas Dattatray , Huple Deepak B. , Liu Rai‐Shung
Published: August 2016

Gold‐catalyzed oxidations of 2‐ketonyl‐1‐ethynyl benzenes with N‐hydroxyanilines yield 2‐aminoindenone derivatives efficiently. Experimental data suggests that this process involves an α‐oxo gold carbene intermediate, generated from the attack of N‐hydroxyaniline on furylgold carbene intermediate, rather than the typical attack of oxidants on π‐alkynes.