bluuebunny/crossref_metadata_2025 huggingface dataset:
Metasurface‐Enhanced Infrared Spectroscopy: An Abundance of Materials and Functionalities
Authors: John‐Herpin Aurelian , Tittl Andreas , Kühner Lucca , Richter Felix , Huang Steven H. , Shvets Gennady , Oh Sang‐Hyun , Altug Hatice
Published: May 2022

Infrared spectroscopy provides unique information on the composition and dynamics of biochemical systems by resolving the characteristic absorption fingerprints of their constituent molecules. Based on this inherent chemical specificity and the capability for label‐free, noninvasive, and real‐time detection, infrared spectroscopy approaches have unlocked a plethora of breakthrough applications for fields ranging from environmental monitoring and defense to chemical analysis and medical diagnostics. Nanophotonics has played a crucial role for pushing the sensitivity limits of traditional far‐field spectroscopy by using resonant nanostructures to focus the incident light into nanoscale hot‐spots of the electromagnetic field, greatly enhancing light–matter interaction. Metasurfaces composed of regular arrangements of such resonators further increase the design space for tailoring this nanoscale light control both spectrally and spatially, which has established them as an invaluable toolkit for surface‐enhanced spectroscopy. Starting from the fundamental concepts of metasurface‐enhanced infrared spectroscopy, a broad palette of resonator geometries, materials, and arrangements for realizing highly sensitive metadevices is showcased, with a special focus on emerging systems such as phononic and 2D van der Waals materials, and integration with waveguides for lab‐on‐a‐chip devices. Furthermore, advanced sensor functionalities of metasurface‐based infrared spectroscopy, including multiresonance, tunability, dielectrophoresis, live cell sensing, and machine‐learning‐aided analysis are highlighted.
Strain‐Driven Auto‐Detachable Patterning of Flexible Electrodes
Authors: Lv Zhisheng , Wang Changxian , Wan Changjin , Wang Renheng , Dai Xiangyu , Wei Jiaqi , Xia Huarong , Li Wenlong , Zhang Wei , Cao Shengkai , Zhang Feilong , Yang Haiyue , Loh Xian Jun , Chen Xiaodong
Published: May 2022

Flexible electrodes that are multilayer, multimaterial, and conformal are pivotal for multifunctional wearable electronics. Traditional electronic circuits manufacturing requires substrate‐supported transfer printing, which limits their multilayer integrity and device conformability on arbitrary surfaces. Herein, a “shrinkage‐assisted patterning by evaporation” (SHAPE) method is reported, by employing evaporation‐induced interfacial strain mismatch, to fabricate auto‐detachable, freestanding, and patternable electrodes. The SHAPE method utilizes vacuum‐filtration of polyaniline/bacterial cellulose (PANI/BC) ink through a masked filtration membrane to print high‐resolution, patterned, and multilayer electrodes. The strong interlayer hydrogen bonding ensures robust multilayer integrity, while the controllable evaporative shrinking property of PANI/BC induces mismatch between the strains of the electrode and filtration membrane at the interface and thus autodetachment of electrodes. Notably, a 500‐layer substrateless micro‐supercapacitor fabricated using the SHAPE method exhibits an energy density of 350 mWh cm−2 at a power density of 40 mW cm−2, 100 times higher than reported substrate‐confined counterparts. Moreover, a digital circuit fabricated using the SHAPE method functions stably on a deformed glove, highlighting the broad wearable applications of the SHAPE method.
Nanochitin and Nanochitosan: Chitin Nanostructure Engineering with Multiscale Properties for Biomedical and Environmental Applications
Authors: Lee Suyoung , Hao Lam Tan , Park Jeyoung , Oh Dongyeop X. , Hwang Dong Soo
Published: May 2022

Nanochitin and nanochitosan (with random‐copolymer‐based multiscale architectures of glucosamine andN‐acetylglucosamine units) have recently attracted immense attention for the development of green, sustainable, and advanced functional materials. Nanochitin and nanochitosan are multiscale materials from small oligomers, rod‐shaped nanocrystals, longer nanofibers, to hierarchical assemblies of nanofibers. Various physical properties of chitin and chitosan depend on their molecular‐ and nanostructures; translational research has utilized them for a wide range of applications (biomedical, industrial, environmental, and so on). Instead of reviewing the entire extensive literature on chitin and chitosan, here, recent developments in multiscale‐dependent material properties and their applications are highlighted; immune, medical, reinforcing, adhesive, green electrochemical materials, biological scaffolds, and sustainable food packaging are discussed considering the size, shape, and assembly of chitin nanostructures. In summary, new perspectives for the development of sustainable advanced functional materials based on nanochitin and nanochitosan by understanding and engineering their multiscale properties are described.
Systematic Screening and Therapeutic Evaluation of Glyconanoparticles with Differential Cancer Affinities for Targeted Cancer Therapy
Authors: Whang Chang‐Hee , Hong Jungwoo , Kim Dohyeon , Ryu Hong , Jung Wonsik , Son Youngju , Keum Hyeongseop , Kim Jinjoo , Shin Hocheol , Moon Eugene , Noh Ilkoo , Lee Hee‐Seung , Jon Sangyong
Published: May 2022

Cancer‐targeting ligands used for nanomedicines have been limited mostly to antibodies, peptides, aptamers, and small molecules thus far. Here, a library of glycocalyx‐mimicking nanoparticles as a platform to enable screening and identification of cancer‐targeting nanomedicines is reported. Specifically, a library of 31 artificial glycopolymers composed of either homogeneous or heterogeneous display of five different sugar moieties (β‐glucose, β‐galactose, α‐mannose, β‐N‐acetyl glucosamine, and β‐N‐acetyl galactosamine) is converted to a library of glyconanoparticles (GlyNPs). GlyNPs optimal for targeting CT26, DU145, A549, and PC3 tumors are systematically screened and identified. The cypate‐conjugated GlyNP displaying α‐mannose and β‐N‐acetyl glucosamine show selective targeting and potent photothermal therapeutic efficacy against A549 human lung tumors. The docetaxel‐contained GlyNP displaying β‐glucose, β‐galactose, and α‐mannose demonstrate targeted chemotherapy against DU145 human prostate tumors. The results presented herein collectively demonstrate that the GlyNP library is a versatile platform enabling the identification of cancer‐targeting glyconanoparticles and suggest its potential applicability for targeting various diseased cells beyond cancer.
Light‐Controlled Fabrication of Disordered Hyperuniform Metasurfaces
Authors: Shutsko Ivan , Buchmüller Maximilian , Meudt Maik , Görrn Patrick
Published: May 2022

Disordered hyperuniformity (DHU) is one of the most prominent manifestations of the engineered disorder, which aims to circumvent limitations commonly related to order. Considering the k‐space, isotropic DHU is characterized by an isotropic suppression of scattering for wavenumbers k approaching zero. Thereby, stealthy DHU is a particularly strong form of DHU, where scattering is even suppressed for wavenumbers 0 < k ≤ K within a circular window of radius K. Although experimental demonstrations of DHU in optical structures exist, scalable and low‐cost fabrication methods are still rare and often lack the opportunity for in‐situ control of the k‐space. Here, a novel and facile bottom‐up approach for the fabrication of DHU metasurfaces is presented. Starting with a solution‐based deposition procedure of silver nanoparticles (AgNPs) in darkness (resulting in DHU), a more extensive way of in‐situ k‐space engineering is introduced by illuminating the growing metasurface with light (resulting in stealthy DHU). While it is shown that the wavelength of incident light allows for the in‐situ control of K, its lateral momentum k∥ defines an additional design parameter. The light‐controlled growth under maximum k∥ via surface plasmon polaritons enables the experimental confirmation of the theoretically predicted phenomenon of anisotropic stealthy DHU.
Ultrathin GaAs Photovoltaic Arrays Integrated on a 1.4 µm Polymer Substrate for High Flexibility, a Lightweight Design, and High Specific Power
Authors: Cho Sungbum , Jung Dongwuk , Kim Juho , Seo Jimin , Ju Hunpyo , Lee Jongho
Published: May 2022

Lightweight ultrathin solar cells with high efficiency and reliability serve as a convenient untethered power source for new types of electronic devices, such as attachable or implantable electronics, small‐scale robots, and many others. However, the extreme mechanical properties of high‐performance solar cells and ultrathin films present challenges when handling and processing them to realize ultrathin solar cell arrays. In this paper, a highly efficient GaAs photovoltaic array integrated on an ultrathin polymer film (1.4 µm thick) is presented. Full processes, including framing, cold‐welding, epitaxial lift‐off (ELO), and microfabrication, are used to realize ultra‐flexible and lightweight GaAs photovoltaic arrays. The mechanical characteristics are analyzed via numerical and experimental methods along with demonstrations with electrically functional devices. The power‐to‐weight ratio (specific power: 5.44 W g−1) is in the highest range, even with single‐junction solar cells.
Multi‐Channel Metasurface for Versatile Wavefront and Polarization Manipulation
Authors: Shao Linda , Li Zhenfei , Zhang Zhengping , Wang Xiong , Zhu Weiren
Published: May 2022

Metasurfaces are extensively studied for the flexible manipulation of wavefront and polarization of electromagnetic waves with significant merits such as ultra‐thin profiles and low insertion losses. However, conventional meta‐devices are usually limited by achieving only single polarization modulation, and it is challenging to achieve mixed polarization and wavefront manipulation in a single metasurface. Here, a single‐layer anisotropic metasurface for independent wavefront manipulation in multiple polarization channels is presented. The meta‐atom is composed of two orthogonal dumbbell‐shaped metal patches placed on the top of a dielectric layer with grounded plane on the bottom. The reflective phases of the two orthogonal linearly polarized waves can be independently manipulated by changing the dimensions of the dumbbell‐shaped resonator. As a result, not only the propagation phase but also the polarization state of the outgoing wave can be manipulated independently as desired. As proof of concept, a metasurface is designed for converging the reflection beams of four polarization states to specific positions for four‐focus holographic imaging. The measured results are in good agreements with simulated ones, verifying the independent wavefront manipulations with arbitrary polarization conversions.
Self‐Rolling SiO2/Au Based Epsilon‐Near‐Zero Metamaterials
Authors: Habib Mohsin , Issah Ibrahim , Bermúdez‐Ureña Esteban , Caglayan Humeyra
Published: May 2022

Wave propagation in epsilon‐near‐zero (ENZ) media offers exciting possibilities in the field of nanophotonics. Here, a thin film self‐rolling technique to fabricate SiO2/Au based 3D multilayer structures is implemented. These cylindrical multilayer metamaterials are utilized to take advantage of the material dispersion as well as the structural dispersion to obtain self‐rolling ENZ metamaterials at the visible to near‐infrared wavelength range. The ENZ features are investigated initially by modelling the dispersion of the effective medium using circular effective medium approximation and further by the characterization of the optical response. Moreover, the potential of these structures for supporting an ENZ waveguide mode is demonstrated. This platform for dispersion engineering and obtaining ENZ metamaterials can provide opportunities for unique applications which cannot be possible with planar systems. It can be used to integrate active materials before the rolling process to actively control the layer properties, or embed single‐layer materials within different layers of ENZ metamaterials with potential applications in quantum nanophotonics.
Visible‐Light‐Enabled Photosensitizer‐ and Additive‐Free Decarboxylative Coupling Cyclization of Enaminone withN‐Arylglycine for 3‐Aminoalkyl Chromones
Authors: Zhu Zhi‐Qiang , Hu Jia‐Yu , Xie Zong‐Bo , Tang Juan , Le Zhang‐Gao
Published: May 2022

An photosensitizer‐ and additive‐free, visible‐light‐induced decarboxylative aminoalkylation/C−O coupling cyclization of enaminones withN‐arylglycine for the synthesis of 3‐aminoalkyl chromones has been achieved. This synthetic method features good functional‐group tolerance, mild reaction conditions and no request of photocatalyst or additive, thus making this protocol more practical and sustainable.

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Fabrication and Optimization of CdSe Solar Cells for Possible Top Cell of Silicon‐Based Tandem Devices
Authors: Li Kanghua , Yang Xuke , Lu Yue , Xue Jiayou , Lu Shuaicheng , Zheng Jiajia , Chen Chao , Tang Jiang
Published: May 2022

Silicon‐based tandem solar cells are regarded as one of the most feasible ways to break the single‐junction Shockley–Queisser limit efficiency and further reduce the cost of solar electricity. Recently, wide‐bandgap (≈1.7 eV) perovskite solar cells have drawn intense research interest as the top cell for Si‐based tandem devices. Despite significant progress in device efficiency, the unsatisfactory stability of perovskites is still a huge concern. Besides halide perovskites, there are many inorganic semiconductors worthy of investigation. It is believed that cadmium selenide, a binary compound enjoying outstanding optoelectronic properties, high stability, and low cost, is very promising as the top cell for Si‐based tandem devices. Herein, the CdSe thin‐film solar cells that have been neglected for 3 decades are revisited. Using rapid thermal evaporation, high‐quality CdSe thin films with large grain size, high‐photoluminescence, small Stokes shift, and intrinsic n‐type conductivity are obtained. Furthermore, CdSe solar cells are redesigned and a champion efficiency of 6.00% is achieved. Through in‐depth analysis, it is identified that bulk and interface defects limit the open‐circuit voltage and hence device performance. This work highlights the great potential of CdSe solar cells as top cells for Si‐based tandem devices.
Inhalation‐Driven Vertical Flutter Triboelectric Nanogenerator with Amplified Output as a Gas‐Mask‐Integrated Self‐Powered Multifunctional System
Authors: Heo Deokjae , Song Myunghwan , Chung Seh‐Hoon , Cha Kyunghwan , Kim Youna , Chung Jihoon , Hwang Patrick T.J. , Lee Jaeheon , Jung Heesoo , Jin Youngho , Hong Jinkee , Kim Min‐Kun , Lee Sangmin
Published: May 2022

With the widespread use of sensors and small electronics in the Internet of Things (IoT) era, triboelectric nanogenerators (TENGs) have emerged as sustainable and renewable energy sources owing to their high efficiency, compatibility with various materials, and low cost. However, the existing TENGs exhibit a low current output and require a large mechanical input to continuously generate an enhanced current output. In this study, an inhalation‐driven vertical flutter TENG (IVF‐TENG) with an amplified current output is developed. The IVF‐TENG exhibits two types of mechanical behaviors simultaneously, generating a high‐frequency continuous electrical voltage and closed‐circuit current (ICC) output of 17 V and 1.84 μA, respectively, during inhalation, and an electrostatic discharge voltage and ICC output of 456 V and 288 mA at the beginning and end of every inspiratory cycle, respectively. As a user‐position‐indicating light, the IVF‐TENG can power 130 LEDs in series and 140 LEDs in parallel for every inhalation. The IVF‐TENG can charge a capacitor of 660 μF, with a discharge process of a few seconds, to power a commercial Bluetooth tracker and wirelessly transfer the Bluetooth signal to a smartphone. Moreover, the IVF‐TENG can detect the user's respiration state or the presence of chemical warfare agents (GB, DMMP, etc.) via output waveforms.
Anode‐Free Solid‐State Lithium Batteries: A Review
Authors: Huang Wen‐Ze , Zhao Chen‐Zi , Wu Peng , Yuan Hong , Feng Wei‐Er , Liu Ze‐Yu , Lu Yang , Sun Shuo , Fu Zhong‐Heng , Hu Jiang‐Kui , Yang Shi‐Jie , Huang Jia‐Qi , Zhang Qiang
Published: May 2022

Anode‐free solid‐state lithium batteries are promising for next‐generation energy storage systems, especially the mobile sectors, due to their enhanced energy density, improved safety, and extended calendar life. However, the inefficiency of lithium plating and stripping leads to rapid capacity degradation due to the absence of excess lithium inventory. Therefore, dissecting the difficulties and challenges faced by anode‐free solid‐state lithium batteries can pave the way to improving the cycle life of many lithium batteries. In this review, the key issues affecting capacity degradation are elaborated step‐by‐step based on the current understanding of anode‐free solid‐state lithium batteries. Furthermore, various strategies for optimizing performance are targeted. Finally, future opportunities and possible directions for anode‐free solid‐state lithium batteries are evaluated, aiming to stimulate the exploration of this emerging field.
Synergistic Effect of Band and Nanostructure Engineering on the Boosted Thermoelectric Performance of n‐Type Mg3+δ(Sb, Bi)2 Zintls
Authors: Liang Ji‐Sheng , Shi Xiao‐Lei , Peng Ying , Liu Wei‐Di , Yang Heng‐Quan , Liu Cheng‐Yan , Chen Jun‐Liang , Zhou Qi , Miao Lei , Chen Zhi‐Gang
Published: May 2022

Thermoelectric Mg3+δ(Sb, Bi)2 Zintls have attracted significant attention because of their high‐performing, eco‐friendly, and cost‐effective features, but their thermoelectric properties still need improvement for application to practical devices. Here an outstanding ZT of ≈1.87 at 773 K and a high average ZT of ≈1.2 in n‐type Y‐doped Mg3.2Sb1.5Bi0.49Se0.01 are reported, both of which rank as top values among the reported literature. First‐principles calculations indicate that substituting the Mg site with Y shifts the Fermi level into the conduction band and simultaneously narrows the bandgap, both strengthening the n‐type semiconducting feature and boosting the electron carrier density of Mg3.2Sb1.5Bi0.49Se0.01. A high power factor of ≈21.4 µW cm–1 K–2 is achieved at 773 K in Mg3.18Y0.02Sb1.5Bi0.49Se0.01, benefiting from the rationally tuned carrier density of ≈7.7 × 1019 cm–3 at this temperature. In addition, the doped Ys act as point defects to cause significant lattice distortions and strains, confirmed by comprehensive micro/nanostructure characterizations. These lattice imperfections suppress the lattice thermal conductivity to ≈0.41 W m–1 K–1 at 773 K, leading to such a high ZT. Furthermore, a high energy conversion efficiency of ≈13.8% is predicted by a temperature gradient of 450 K, indicating a great potential to be applied to practical devices for mid‐temperature applications.
Emerging Strategies toward Mechanically Robust Organic Photovoltaics: Focus on Active Layer
Authors: Yan Cenqi , Qin Jiaqiang , Wang Yinghan , Li Gang , Cheng Pei
Published: May 2022

Mechanical stability of organic photovoltaics (OPVs) is required not just for portable applications, which must accommodate strain as a function of operation, but also for manufacturing, transportation, and utility‐scale applications. However, the mechanical reliability of OPVs is often disregarded compared with other stress (thermal, oxygen, moisture, irradiation). The key to improving the mechanical stability of OPVs lies in realizing mechanically robust active layers. This perspective first analyzes working scenarios of flexible OPVs (static and dynamic conditions) and strategies toward achieving mechanically robust active layers. Then, the recent achievements in improving the mechanical robustness of active layers are summarized in the aspects of all‐polymer active layers, single‐component active layers, and third component strategies. In the end, an outlook and perspective on the future of the field are provided to help improve the mechanical stability of active layers.
Increasing the Pressure‐Free Stripping Capacity of the Lithium Metal Anode in Solid‐State‐Batteries by Carbon Nanotubes
Authors: Fuchs Till , Haslam Catherine G. , Moy Alexandra C. , Lerch Christian , Krauskopf Thorben , Sakamoto Jeff , Richter Felix H. , Janek Jürgen
Published: May 2022

Lithium metal is the key anode material for solid‐state‐batteries as its successful implementation will drastically increase their energy and power densities. However, anode contact loss during stripping leads to dendrites upon plating and subsequent cell failure. Design strategies to mitigate these issues are crucial to enable the use of lithium metal anodes. This paper reports the dissolution kinetics of composite anodes made of lithium metal and carbon nanotubes (CNTs) with a garnet‐type solid electrolyte (SE). In addition to an enhancement of the effective diffusion within the anode, its dissolution is fundamentally changed from being 2D to 3D. By maintaining contact with the SE, the CNTs facilitate lithium transport to the interface, which yields more than 20 mAh cm−2 discharge capacity at 100 µA cm−2 without the application of external stack pressure (>1 MPa). Conclusions drawn from electrochemical data on the anode microstructure are validated using cryo‐focused‐ion‐beam scanning electron microscopy and correlated with the mechanical properties. Micro‐indentation, acoustic analysis, and stress–strain testing show that mechanical properties of the anode, like yield strength and hardness, are adjustable. Overall, it is shown that the mechanical and electrochemical properties of Li–CNT composite electrodes can be tailored to suit the requirements of a practical cell.
Optical properties of gold nanoclusters constructed from Au13 units
Authors: Kong Jie , Zhang Wei , Wu Yanzhen , Zhou Meng
Published: May 2022

Atomically precise gold nanoclusters with diameters of 1–3 nm have attracted considerable research interests in the past decade because they fill the gap between small organic‐metal complexes (<1 nm) and metal nanoparticles (>3 nm). Au13 nanocluster with icosahedral structure is a ubiquitous unit widely applied in nanocluster assembly. In this minireview, we introduce the optical properties of gold nanoclusters constructed from Au13 units. We first discuss the optical absorption and photoluminescence of Au13, Au25, Au37, and Au60 clusters. We then discuss the ultrafast dynamics, the detailed excited‐state deactivation processes, and the origin of coherent oscillations of the Au13 homologous clusters. Finally, we provide our outlook on the future direction on this topic.
Patterns of venous thromboembolism risk, treatment, and outcomes among patients with cancer from uninsured and vulnerable populations
Authors: da Costa Wilson L. , Guffey Danielle , Oluyomi Abiodun , Bandyo Raka , Rosales Omar , Wallace Courtney D. , Granada Carolina , Riaz Nimrah , Fitzgerald Margaret , Garcia David A. , Carrier Marc , Amos Christopher I. , Flowers Christopher R. , Li Ang
Published: May 2022

The epidemiology of cancer‐associated thrombosis (CAT) among uninsured and vulnerable populations in the US is not well‐characterized. We performed a retrospective cohort study for patients with newly diagnosed cancer from 2011 to 2020 at Harris Health System, which cares for uninsured residents in the Houston metropolitan area. Patient demographics, NCI comorbidity index, area of deprivation index (ADI), cancer histology, staging, and systemic therapy data were extracted. CAT included overall venous thromboembolism (VTE) or pulmonary embolism +/− lower extremity deep vein thrombosis (PE/LE‐DVT) within 1 year of diagnosis. We used multivariable Fine‐Gray models to assess the associations with CAT accounting for death as a competing risk. Among 15 342 patients, 74% were uninsured and 84% lived in socioeconomically disadvantaged neighborhoods. There were 16% Non‐Hispanic White (NHW), 28% Non‐Hispanic Black (NHB), 50% Hispanic (27% Mexican), and 6% Asian/Pacific Islanders (API). The 1‐year CAT incidence rate was 14.6%. Overall VTE was lower for Hispanics versus NHW (SHR 0.87 [0.76–0.99]) and API versus NHW (SHR 0.58 [0.44–0.77]). PE/LE‐DVT was higher for NHB versus NHW (SHR 1.18 [1.01–1.39]). CAT was also associated with chemotherapy‐based regimens (+/− immunotherapy), age, obesity, cancer type/staging, VTE history, and recent hospitalization. NCI comorbidity and ADI scores were associated with mortality but not CAT. In a large cohort of underserved patients with cancer, we identified an elevated incidence of CAT with known and novel risk predictors. Hispanics had lower adjusted rates of CAT and mortality. Our findings highlight the need to investigate and incorporate vulnerable populations in clinical trials.
Transition‐Metal‐Catalyzed Remote C(sp3)−H Functionalization Of Carboxylic Acid And Its Derivatives
Authors: Shahid M. , Banakar Vijay Basavaraj , Prabhakar Ganesh Pothapragada S. K. , Gopinath Purushothaman
Published: May 2022

Carboxylic acids are ubiquitous functional groups present in many bio‐relevant molecules, including drugs and amino acids. In general, α‐ and β−C(sp3)−H bonds of carboxylic acids are easy to functionalize, contrary to remote (γ‐ and δ) C−H bonds which are difficult due to the distal location of these C−H bonds from the functional group. On the other hand, functionalizing an inert C(sp3)−H bond is another critical challenge in synthetic chemistry due to its lower acidity and reactivity. Nevertheless, the last decade has witnessed tremendous development in remote sp3‐C−H bond functionalization of carboxylic acid and its derivatives. Here, in this review, we have delineated recent progress in remote γ‐ and δ‐C−H bond functionalization of aliphatic carboxylic acids/amino acids and their derivatives. This review is further subdivided based on the type of functionalization reaction. Finally, we have presented some applications of these methodologies, such as total synthesis of hibispeptin A, etc.
Self‐consistent theory of dynamic melting of a vortex lattice
Authors: Grundberg Staffan , Rammer Jørgen
Published: May 2022

The dynamic melting of vortex lattices in type II superconductors is considered. A field‐theoretic formulation of the pinning problem allows the average over the quenched disorder to be performed exactly. A self‐consistent theory is constructed using a functional method for the effective action, allowing a determination of the pinning force and the vortex fluctuations. The phase diagram for the dynamic melting transition is determined numerically. In contrast to perturbation theory, the self‐consistent theory is in quantitative agreement with the prediction of a recent phenomenological theory and simulations and experimental data.
Rotating cylindrical systems and gravitomagnetism
Authors: Mashhoon B. , Santos N.O.
Published: May 2022

We discuss gravitomagnetism in connection with rotating cylindrical systems. In particular, the gravitomagnetic clock effect is investigated for the exterior vacuum field of an infinite rotating cylinder. The dependence of the clock effect on the parameters of the stationary Lewis metric is determined. We illustrate our results by means of the van Stockum spacetime.
Conductivity of heavily doped Si:P under uniaxial stress
Authors: Waffenschmidt S. , v. Löhneysen H.
Published: May 2022

Barely insulating, uncompensated Si:P samples have been tuned through the metal‐insulator transition applying uniaxial stress along the [100] direction. We find a critical exponent μ ≈︂ 1 of the electrical conductivity extrapolated to temperature T = 0, i.e. σ(T → 0,S) ∼ |S — Sc|μ, in disagreement with earlier stress tuning studies along [123‐] where μ ≈︂ 0.5 was reported. Varying the stress or the concentration leads to a different T dependence of σ(T). Our stress‐tuning measurements obey finite‐T scaling with a dynamic exponent z = 3.
Interface of General Relativity, Quantum Physics and Statistical Mechanics: Some Recent Developments
Authors: Ashtekar A.
Published: May 2022

The arena normally used in black holes thermodynamics was recently generalized to incorporate a broad class of physically interesting situations. The key idea is to replace the notion of stationary event horizons by that of ‘isolated horizons.’ Unlike event horizons, isolated horizons can be located in a space‐timequasi‐locally. Furthermore, they need not be Killing horizons. In particular, a space‐time representing a black hole which is itself in equilibrium, but whose exterior contains radiation, admits an isolated horizon. In spite of this generality, the eroth and first laws of black hole mechanics extend to isolated horizons. Furthermore, by carrying out a systematic, non‐perturbative quantization, one can explore the quantum geometry of isolated horizons and account for their entropy from statistical mechanical considerations. After a general introduction to black hole thermodynamics as a whole, these recent developments are briefly summarized.
Exact radiative spacetimes: some recent developments
Authors: Bičák J.
Published: May 2022

Five classes of radiative solutions of Einstein's field equations are discussed in the light of some new developments. These are plane waves and their collisions, cylindrical waves, Robinson‐Trautman and type N spacetimes, boost‐rotation symmetric spacetimes and generali ed Gowdy‐type cosmological models.
Strings and black holes
Authors: Damour T.
Published: May 2022

I review some recent work (done in collaboration with G. Veneziano) which clarifies the existence of a correspondence between self‐gravitating fundamental string states and Schwarzschild black holes. The main result is a detailed calculation showing that self‐gravity causes a typical string state of mass M to shrink, as the string coupling g2 increases, down to a compact string state whose mass, size, entropy and luminosity match (for the critical value those of a Schwarzschild black hole. This confirms the idea that the entropy of black holes can be accounted for by counting string states, and suggests that the level spacing of the quantum states of Schwarzschild black holes is exponentially small, and very much blurred by radiative effects.
Foundations of Gravitational Lens Theory (Geometry of Light Cones)
Authors: Ehlers J.
Published: May 2022

The main concepts of gravitational lens theory are introduced on the basis of spacetime geometry without assuming approximations. The singularities of light cones, in particular their caustics, are reviewed as examples of singularities of Lagrangian resp. Legendrian maps. It is indicated how the usual approximate lens theory may be derived from the general framework.
An exact gravitational wave solution
Authors: Kramer D.
Published: May 2022

An exact solution describing an axisymmetric gravitational wave propagating in z ‐direction is given in closed form. This solution to Einstein's vacuum field equations has no curvature singularities, in particular it is regular at the symmetry axis. The gravitational wave solution has the nice property that the curvature invariants tend to zero with increasing distance from the axis.
Gravitational Wave Astronomy
Authors: Nollert H.‐P.
Published: May 2022

Gravitational waves, as predicted by the theory of General Relativity, have been studied theoretically for many decades. However, due to the weak coupling of gravitation with matter, it has not yet been possible to measure them directly. Up to now, we only have indirect evidence of the existence and the effect of gravitational radiation by pulsar timing measurements. New gravitational wave detectors, using laser interferometry, offer the chance of observing gravitational waves directly in the near future, paving the way to a new branch of astronomy, gravitational wave astronomy. In this article, we give a brief review of the techniques which can be used for the detection of gravitational waves, and of the astronomical sources which may emit them, making them candidates for observation through gravitational radiation.
Rotating perfect fluid models in general relativity
Authors: Perjés Z.
Published: May 2022

The various schemes for studying rigidly rotating perfect fluids in general relativity are reviewed. General conclusions one may draw from these are: (i) There is a need to restrict the scope of the possible ansätze, and (ii) the angular behaviour is a valuable commodity. This latter observation follows from a large number of analytic models exhibiting a NUT‐like behaviour. A method of getting around problem (ii) is presented on a simple example. To alleviate problem (i) for rigidly rotating perfect fluids, approximation schemes based on a series expansion in the angular velocity are suggested. A pioneering work, due to Hartle, explores the global properties of matched space‐times to quadratic order in the angular velocity.

As a first example of the applications, it is shown that the rigidly rotating incompressible fluid cannot be Petrov type D.
Resolution deterioration in emission electron microscopy due to object roughness
Authors: Nepijko S.A. , Sedov N.N. , Schönhense G. , Escher M. , Bao Xinhe , Huang Weixin
Published: May 2022

In the present paper a general analytic expression has been obtained and confirmed by a computer simulation which links the surface roughness of an object under study in an emission electron microscope and it's resolution. A quantitative derivation was made for the model case when there is a step on the object surface. It was shown that the resolution is deteriorated asymmetrically relative to the step. The effect sets a practical limit to the ultimate lateral resolution obtainable in an emission electron microscope.
Dislocation theory as a 3‐dimensional translation gauge theory
Authors: Lazar Markus
Published: May 2022

We consider the static elastoplastic theory of dislocations in an elastoplastic material. We use a Yang‐Mills type Lagrangian (the teleparallel equivalent of Hilbert‐Einstein Lagrangian) and some Lagrangians with anisotropic constitutive laws. The translational part of the generalized affine connection is utilized to describe the theory of elastoplasticity in the framework of a translation gauge theory. We obtain a system of Yang‐Mills field equations which express the balance of force and moment.
Tunnelling of topological line defects in strongly coupled superfluids
Authors: Fischer Uwe R.
Published: May 2022

The geometric theory of vortex tunnelling in superfluid liquids is developed. Geometry rules the tunnelling process in the approximation of an incompressible superfluid, which yields the identity of phase and configuration space in the vortex collective co‐ordinate. To exemplify the implications of this approach to tunnelling, we solve explicitly for the two‐dimensional motion of a point vortex in the presence of an ellipse, showing that the hydrodynamic collective co‐ordinate description limits the constant energy paths allowed for the vortex in configuration space. We outline the experimental procedure used in helium II to observe tunnelling events, and compare the conclusions we draw to the experimental results obtained so far. Tunnelling in Fermi superfluids is discussed, where it is assumed that the low energy quasiparticle excitations localised in the vortex core govern the vortex dynamical equations. The tunnelling process can be dominated by Hall or dissipative terms, respectively be under the influence of both, with a possible realization of this last intermediate case in unconventional, high‐temperature superconductors.
Functional Schrödinger picture approach to a dilute bose gas and fluctuation correction to the ground state energy density
Authors: Kim Sang‐Hoon , Noh Hyun Sik , Kim Dae Kwan , Kim Chul Koo , Nahm Kyun
Published: May 2022

A many‐body theoretical scheme based on the functional Schrödinger picture method is formulated for the study of a dilute Bose gas system. The standard ground state properties are obtained by solving the infinite dimensional Schr�dinger equation variationally with a Gaussian trial wavefunctional. It is shown that a shifted Gaussian trial functional enables us to calculate a higher order correction of order na3, which corresponds to the fluctuation constribution from the condensate.
Quantum hexaspherical observables for electrons
Authors: Jaekel Marc‐Thierry , Reynaud Serge
Published: May 2022

A new quantum algebraic description of relativistic electrons, built on a conformal dynamical symmetry (SO(4,2 )), has recently been proposed to treat localization in space‐time. It is shown here that localization of an electron may be represented by components of a SO(4,2) vector which are quantum generalizations of the hexaspherical coordinates of classical projective geometry. The shift of this vector under transformations to uniformly accelerated frames is described by SO(4,2) rotations. Hexaspherical observables also allow one to represent the quantum law of free fall under a form explicitly compatible with the same dynamical symmetry.
Energy landscape and fluctuations in proteins
Authors: Frauenfelder H. , McMahon B.H.
Published: May 2022

Complex systems such as biomolecules or glasses do not exist in a unique structure, but can assume a very large number of somewhat different conformations. The organization of the conformations can be described in the energy (or conformation) landscape, where individual valleys are called conformational substates. Proteins are systems where the energy landscape has been studied in some detail. Their landscape is organized in a hierarchy that contains three types of substates, taxonomic, statistical, and few‐level. Conformational substates are found in a wide variety of proteins. Some of their characteristics are described and the open experimental and theoretical problems are listed.
A renormalization approach to quantum thermal annealing
Authors: Lee Yong‐ Han , Berne B.J.
Published: May 2022

The details of an efficient global optimization approach, quantum thermal annealing with renormalization (QTAR) (Y. H. Lee and B. J. Berne, J. Phys. Chem. A, in press (2000)) are presented in this paper. This method is based on the application of the Migdal‐Kadanoff method for decimating Trotter time slices in the staging and primitive algorithms for sampling path integrals using Monte Carlo methods. In a nutshell, one starts in a strong quantum regime where the number of Trotter beads representing each quantum particle and the value of Planck's constant are large, thereby allowing for efficient tunneling through the barriers of a rough energy landscape typical in the folding of proteins, and anneals the system methodically to the classical limit where the values of the aforementioned quantities are 1 and 0, respectively. Global optimization of the system is achieved through the iterative use of such quantum‐to‐classical annealing cycles. The QTAR algorithm applied to a highly frustrated BLN model protein with 46 residues more efficiently locates the global energy minimum than established methods like simulated annealing.
The heartbeat of extended clocks
Authors: Jung P. , Gailey P.C.
Published: May 2022

We show that a combination of noise and self‐organization in purely excitable media can give rise to the formation of local almost periodic pacemakers. We present numerical studies of such pacemakers and provide approximate analytic estimates of their frequencies.
Markov processes driven by quasi‐periodic deterministic forces
Authors: Talkner Peter
Published: May 2022

Quasi‐periodically driven Markovian systems are rendered stationary by enlarging the state space. The eigenvalues and eigenvectors of the master operator of the enlarged process are considered for very slow driving forces in the adiabatic limit. This limit has to be performed always in the minimally enlarged state space and, for two driving frequencies in general leads to results that discontinuously depend on the frequency ratio.
Pipeline model of a Fermi‐sea electron pump
Authors: Sols Fernando , Wagner Mathias
Published: May 2022

The use of a band offset between the two leads of an electron pump driven by a local oscillating voltage is shown to increase the pump current dramatically. The structure of the electron transmission suggests the existence of dominant inelastic channels which we call pipelines. This permits the formulation of a simple model that gives a physical account of the numerical results for a realistic device. A spectral analysis reveals the pump current to be carried by scattering states with initial energy deep within the Fermi sea and not at its surface, thereby rendering the effect insensitive to temperature. We show this is compatible with the current flowing near the Fermi surface in the leads.
Nonlinear quantum transport and current noise
Authors: Lang Gunther , Weiss Ulrich
Published: May 2022

We study nonequilibrium transport and noise in a genericdissipative tightbinding model. Within a real‐time path integral approach, we derive formally exact series expressions in the number of tunneling events for the noise valid for arbitrary bias, frequency and temperature. At zero temperature, the low‐frequency noise can be summed in analytic form.The resulting Shiba‐like |ω|‐singularity is a consequence of the 1/t2 decay law for the current correlation function. At finite temperature, this singularity is smoothed out.
Quantum physics of entangled systems: Wave‐particle duality and atom‐photon molecules
Authors: Rempe G.
Published: May 2022

One of the cornerstones of quantum physics is the wave nature of matter. It explains experimentally observed effects like interference and diffraction, occurring when an object moves from one place to another along several indistinguishable ways simultaneously. The wave nature disappears when the individual ways are distinguishable. In this case, the particle nature of the object becomes visible. To determine the particle nature quantitatively, the way of the object has to be measured. Here, large progress has been made recently with new techniques, enabling one to investigate single moving atoms in a controlled manner. Two examples are discussed in the following two sections. The first experiment describes an atom interferometer, where the way of the atom is entangled with its internal state. This allows one to explore the origin of wave‐particle duality and perform a quantitative test of this fundamental principle. The second experiment reports on the observation of an atom‐photon molecule, a bound state between an atom and a single photon. A fascinating aspect of this system is that it makes possible to monitor the motion of a single neutral atom in real time.
Einselection and decoherence from an information theory perspective
Authors: Zurek W.H.
Published: May 2022

We introduce and investigate a simple model of conditional quantum dynamics. It allows for a discussion of the information‐theoretic aspects of quantum measurements, decoherence, and environment‐induced superselection (einselection).
Phonons: The second type of quantum excitations discovered
Authors: Cardona M.
Published: May 2022

After the discovery of the quantum nature of the electromagnetic radiation by Planck in 1900, the concept of photons was introduced by Einstein in 1905. In 1907 Einstein also introduced quantified lattice vibrations (today called phonons) in order to explain the temperature dependence of the specific heat of crystals. In recent years, the availability of isotopically pure elements has facilitated the growth of crystals with variable isotopic concentration. With these crystals, several quantum effects concerning the ero‐point vibrational amplitudes of phonons have been investigated. Among them we discuss here the anharmonic renormalization of phonon lineshapes.
Heavy‐fermion systems
Authors: Fulde P.
Published: May 2022

Different scenarios of heavy‐fermion behaviour are pointed out. They include Kondo lattices, the Zeeman effect and special forms of charge ordering. Specific examples for the three cases are discussed, i.e., CeRu2Si2, Nd2—xCexCuO4 and Yb4As3.
Nano‐scale studies of quantum phenomena by scanning probe spectroscopy
Authors: Wiesendanger R.
Published: May 2022

Phenomena on the nanometer scale are dominated by quantum effects. They can be visualized in a fascinating way either by the scanning tunneling microscope (STM), which itself is based on a quantum‐mechanical effect, electron tunneling, or by related scanning probe methods. These so‐called near‐field microscopies allow the direct observation of the wave nature of electrons in solids and the determination of their effective mass as well as their spin state. Atomic resolution is obtained by STM on an energy scale which is a million times smaller than that of X‐rays. Therefore, quantum effects in solids, which usually occur on energy scales of several millielectronvolts, become accessible while operating at high spatial resolution down to the atomic level. The detailed understanding of quantum phenomena at the nanometer scale will constitute the foundations of the nanotechnology age, which will be dominated by the digital control of matter at the level of single atoms and molecules, single electrons, as well as single spins.
Relativity and quantum theory from Sommerfeld to Dirac
Authors: Kragh H.
Published: May 2022

Quantum theory and the special theory of relativity emerged almost simultaneously. Through the formative years of quantum theory, from 1900 to about 1928, arguments based on the theory of relativity were of great importance. Starting with Sommerfeld's theory of the hydrogen atom, this paper surveys the ways in which the two fundamental theories have interacted. Relativity was of particular importance in Schrödinger's route to wave mechanics, a theory which was originally conceived as fully integrated with special relativity. The problem of uniting, or harmonising, quantum mechanics and relativity continued to occupy physicists in 1926–27. The paper ends with the solution of this problem, as it was presented in 1928 by Dirac in his seminal paper on the quantum theory of electrons. It also refers to the few attempts there were in the period to formulate a quantum theory in agreement with the general theory of relativity.
The Compton effect: Transition to quantum mechanics
Authors: Stuewer R.H.
Published: May 2022

The discovery of the Compton effect at the end of 1922 was a decisive event in the transition to the new quantum mechanics of 1925‐1926 because it stimulated physicists to examine anew the fundamental problem of the interaction between radiation and matter. I first discuss Albert Einstein's light‐quantum hypothesis of 1905 and why physicists greeted it with extreme skepticism, despite Robert A. Millikan's confirmation of Einstein's equation of the photoelectric effect in 1915. I then follow in some detail the experimental and theoretical research program that Arthur Holly Compton pursued between 1916 and 1922 at the University of Minnesota, the Westinghouse Lamp Company, the Cavendish Laboratory, and Washington University that culminated in his discovery of the Compton effect. Surprisingly, Compton was not influenced directly by Einstein's light‐quantum hypothesis, in contrast to Peter Debye and H.A. Kramers, who discovered the quantum theory of scattering independently. I close by discussing the most significant response to that discovery, the Bohr‐Kramers‐Slater theory of 1924, its experimental refutation, and its influence on the emerging new quantum mechanics.
A single trapped atom: Light‐matter interaction at the microscopic level
Authors: Gomer V. , Meschede D.
Published: May 2022

For a single trapped atom the fluctuations of resonance fluorescence reveal its dynamic evolution at all relevant time scales. We review experimental results, extend interpretations and express expectations for future systems with fully controlled quantum properties.