scholarly journals SPACETIME SINGULARITIES: RECENT DEVELOPMENTS

2013 ◽  
Vol 22 (03) ◽  
pp. 1330002 ◽  
Author(s):  
CLAES UGGLA

Recent developments concerning oscillatory spacelike singularities in general relativity are taking place on two fronts. The first treats generic singularities in spatially homogeneous cosmology, most notably Bianchi types VIII and IX. The second deals with generic oscillatory singularities in inhomogeneous cosmologies, especially those with two commuting spacelike Killing vectors. This paper describes recent progress in these two areas: in the spatially homogeneous case, focus is on mathematically rigorous results, while analytical and numerical results concerning generic behavior and so-called recurring spike formation are the main topics in the inhomogeneous case. Unifying themes are connections between asymptotic behavior, hierarchical structures and solution generating techniques, which provide hints for a link between the nature of generic singularities and a hierarchy of hidden asymptotic symmetries.

2021 ◽  
Vol 2 (1) ◽  
pp. 168-186
Author(s):  
Bahareh Vafakish ◽  
Lee D. Wilson

The nanoreactor concept and its application as a modality to carry out chemical reactions in confined and compartmentalized structures continues to receive increasing attention. Micelle-based nanoreactors derived from various classes of surfactant demonstrate outstanding potential for chemical synthesis. Polysaccharide (glycan-based) surfactants are an emerging class of biodegradable, non-toxic, and sustainable alternatives over conventional surfactant systems. The unique structure of glycan-based surfactants and their micellar structures provide a nanoenvironment that differs from that of the bulk solution, and supported by chemical reactions with uniquely different reaction rates and mechanisms. In this review, the aggregation of glycan-based surfactants to afford micelles and their utility for the synthesis of selected classes of reactions by the nanoreactor technique is discussed. Glycan-based surfactants are ecofriendly and promising surfactants over conventional synthetic analogues. This contribution aims to highlight recent developments in the field of glycan-based surfactants that are relevant to nanoreactors, along with future opportunities for research. In turn, coverage of research for glycan-based surfactants in nanoreactor assemblies with tailored volume and functionality is anticipated to motivate advanced research for the synthesis of diverse chemical species.


ILR Review ◽  
1994 ◽  
Vol 48 (1) ◽  
pp. 5-27 ◽  
Author(s):  
John T. Addison ◽  
W. Stanley Siebert

This paper assesses the recent progress and future direction of labor policy in the European Community, now the European Union. The authors show that most of the mandates foreshadowed under the December 1989 Community Social Charter have now been enacted into law. They analyze the possible costs, as well as the benefits, of these firstphase mandates and show the link between these adjustment costs and the Community's policy of providing subsidies to its poorer member states. They also demonstrate how the new Treaty on European Union, agreed to at Maastricht in December 1991, has increased the scope for Community-level labor market regulation.


2017 ◽  
Vol 8 (6) ◽  
pp. 1701415 ◽  
Author(s):  
Limin Zhou ◽  
Kai Zhang ◽  
Zhe Hu ◽  
Zhanliang Tao ◽  
Liqiang Mai ◽  
...  

1994 ◽  
Vol 06 (05a) ◽  
pp. 887-899 ◽  
Author(s):  
IAN AFFLECK

Integer-spin Heisenberg antiferromagnetic chains are expected to have a singlet groundstate and a gap to the first excited state, as first argued by Haldane. We review rigorous results on this conjecture and discuss experimental realizations. Theoretical and experimental aspects of three recent developments in this field are then reviewed: chainend excitations and the non-local order parameter, a field theory mapping and behavior near zero wave-vector, high-field behavior and one-dimensional Bose condensation.


2020 ◽  
Vol 4 (1) ◽  
pp. 9 ◽  
Author(s):  
Atsushi Momose ◽  
Hidekazu Takano ◽  
Yanlin Wu ◽  
Koh Hashimoto ◽  
Tetsuo Samoto ◽  
...  

Under the JST-ERATO project in progress to develop X-ray and neutron phase-imaging methods together, recent achievements have been selected and reviewed after describing the merit and the principle of the phase imaging method. For X-ray phase imaging, recent developments of four-dimensional phase tomography and phase microscopy at SPring-8, Japan are mainly presented. For neutron phase imaging, an approach in combination with the time-of-flight method developed at J-PARC, Japan is described with the description of new Gd grating fabrication.


2020 ◽  
Vol 21 (23) ◽  
pp. 9224 ◽  
Author(s):  
Simonas Ramanavicius ◽  
Arunas Ramanavicius

Recent progress in the application of new 2D-materials—MXenes—in the design of biosensors, biofuel cells and bioelectronics is overviewed and some advances in this area are foreseen. Recent developments in the formation of a relatively new class of 2D metallically conducting MXenes opens a new avenue for the design of conducting composites with metallic conductivity and advanced sensing properties. Advantageous properties of MXenes suitable for biosensing applications are discussed. Frontiers and new insights in the area of application of MXenes in sensorics, biosensorics and in the design of some wearable electronic devices are outlined. Some disadvantages and challenges in the application of MXene based structures are critically discussed.


MRS Bulletin ◽  
2008 ◽  
Vol 33 (3) ◽  
pp. 226-231 ◽  
Author(s):  
Tony Jun Huang

AbstractArtificial molecular machines capable of converting chemical, electrochemical, and photochemical energy into mechanical motion represent a high-impact, fast-growing field of interdisciplinary research. These molecular-scale systems utilize a “bottom-up” technology centered upon the design and manipulation of molecular assemblies and are potentially capable of delivering efficient actuation at length scales dramatically smaller than traditional microscale actuators. As actuation materials, molecular machines have many advantages, such as high strain (40%–60%), high force and energy densities, and the capability to maintain their actuation properties from the level of a single molecule to the macroscale. These advantages have inspired researchers to develop molecular-machine–based active nanomaterials and nanosystems, including electroactive and photoactive polymers. This article will discuss the structures and properties of artificial molecular machines, as well as review recent progress on efforts to move molecular machines from solution to surfaces to devices.


2010 ◽  
Vol 1 (1) ◽  
pp. 85-96
Author(s):  
Carmen Jiménez-Castells ◽  
Sira Defaus ◽  
David Andreu ◽  
Ricardo Gutiérrez-Gallego

AbstractGlycosylation is probably the most complex secondary gene event that affects the vast majority of proteins in nature resulting in the occurrence of a heterogeneous mixture of glycoforms for a single protein. Many functions are exerted by single monosaccharides, well-defined oligosaccharides, or larger glycans present in these glycoproteins. To unravel these functions it is of the utmost importance to prepare well-defined single glycans conjugated to the underlying aglycon. In this review, the most recent developments are described to address the preparation of carbohydrate-amino acid (glyco-conjugates). Naturally occurring N- and O-linked glycosylation are described and the preparation of non-natural sugar-amino acid linkages are also included.


Nanoscale ◽  
2016 ◽  
Vol 8 (38) ◽  
pp. 16819-16840 ◽  
Author(s):  
Meiying Liu ◽  
Guangjian Zeng ◽  
Ke Wang ◽  
Qing Wan ◽  
Lei Tao ◽  
...  

Recent progress and advances in mussel-inspired surface modification strategies and the biomedical applications of polydopamine-based materials are summarized in this review.


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