Isotropic 3D Research Articles

Coherent States for the Isotropic and Anisotropic 2D Harmonic Oscillators

In this paper we introduce a new method for constructing coherent states for 2D harmonic oscillators. In particular, we focus on both the isotropic and commensurate anisotropic instances of the 2D harmonic oscillator. We define a new set of ladder operators for the 2D system as a linear combination of the x and y ladder operators and construct the S U ( 2 ) coherent states, where these are then used as the basis of expansion for Schrödinger-type coherent states of the 2D oscillators. We discuss the uncertainty relations for the new states and study the behaviour of their probability density functions in configuration space.

Experimental Evidence of Anisotropic and Stable Charged Excitons (Trions) in Atomically Thin 2D ReS2

AbstractExperimentally observed, stable trions with large binding energy (≈25 meV) in atomically thin monolayer 2D transition metal dichalcogenides MX2 (M = Mo, W, X = S, Se, and Te) with an isotropic crystal structure have been extensively studied. In contrast, the characteristics of trions in atomically thin 2D materials with an anisotropic crystal structure are not completely understood. Low‐temperature photoluminescence (PL) spectroscopy in few‐layer ReS2 with an anisotropic crystal structure by applying a gate voltage is described. A new PL peak that emerges below the lower‐energy side of neutral excitons obtained by tuning the gate voltages is attributed to emission from negative trions. Furthermore, the trion binding energy that is strongly dependent on the layer thickness reaches a large value of ≈60 meV in 1L–ReS2, which is ≈2 times larger than that in other isotropic 2D materials (MX2). The enhancement of the binding energy reflects the quasi‐1D nature of the trions in anisotropic atomically thin ReS2. These experimental observations will promote a better understanding of the optical response and applications in new categories of the anisotropic atomically thin 2D materials with a quasi‐1D nature.

Recent advances in MRI of the head and neck, skull base and cranial nerves: new and evolving sequences, analyses and clinical applications.

MRI is an invaluable diagnostic tool in the investigation and management of patients with pathology of the head and neck. However, numerous technical challenges exist, owing to a combination of fine anatomical detail, complex geometry (that is subject to frequent motion) and susceptibility effects from both endogenous structures and exogenous implants. Over recent years, there have been rapid developments in several aspects of head and neck imaging including higher resolution, isotropic 3D sequences, diffusion-weighted and diffusion-tensor imaging as well as permeability and perfusion imaging. These have led to improvements in anatomic, dynamic and functional imaging. Further developments using contrast-enhanced 3D FLAIR for the delineation of endolymphatic structures and black bone imaging for osseous structures are opening new diagnostic avenues. Furthermore, technical advances in compressed sensing and metal artefact reduction have the capacity to improve imaging speed and quality, respectively. This review explores novel and evolving MRI sequences that can be employed to evaluate diseases of the head and neck, including the skull base.

Probing the Surface Structure of Semiconductor Nanoparticles by DNP SENS with Dielectric Support Materials.

Surface characterization is crucial for understanding how the atomic-level structure affects the chemical and photophysical properties of semiconducting nanoparticles (NPs). Solid-state nuclear magnetic resonance spectroscopy (NMR) is potentially a powerful technique for the characterization of the surface of NPs, but it is hindered by poor sensitivity. Dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP SENS) has previously been demonstrated to enhance the sensitivity of surface-selective solid-state NMR experiments by 1-2 orders of magnitude. Established sample preparations for DNP SENS experiments on NPs require the dilution of the NPs on mesoporous silica. Using hexagonal boron nitride (h-BN) to disperse the NPs doubles DNP enhancements and absolute sensitivity in comparison to standard protocols with mesoporous silica. Alternatively, precipitating the NPs as powders, mixing them with h-BN, and then impregnating the powdered mixture with radical solution leads to further 4-fold sensitivity enhancements by increasing the concentration of NPs in the final sample. This modified procedure provides a factor of 9 improvement in NMR sensitivity in comparison to previously established DNP SENS procedures, enabling challenging homonuclear and heteronuclear 2D NMR experiments on CdS, Si, and Cd3P2 NPs. These experiments allow NMR signals from the surface, subsurface, and core sites to be observed and assigned. For example, we demonstrate the acquisition of DNP-enhanced 2D 113Cd-113Cd correlation NMR experiments on CdS NPs and natural isotropic abundance 2D 13C-29Si HETCOR of functionalized Si NPs. These experiments provide a critical understanding of NP surface structures.

Fine/ultrafine particle air filtration and aerosol loading of hollow-fiber membranes: A comparison of mathematical models for the most penetrating particle size and dimensionless permeability with experimental data

Hollow-fiber membranes (HFMs) have widely been applied to many liquid treatment applications such as wastewater treatment, membrane distillation and membrane contactor/bioreactor applications. However, they have rarely been used for aerosol filtration thus far. In this work, we tested air filtration performance of air filter modules composed of polypropylene HFMs. The experimental results of most penetrating particle size (MPPS) and permeability were then compared with theoretically predicted values. Filtration efficiency and MPPS were measured using a monodisperse (20, 35, 50, 70, 100, 140, 280 and 400 nm) and a polydisperse aerosol (15–594 nm). Dimensionless permeability was predicted using models assuming isotropic 3D pore structure and compared with permeability measured using capillary flow porometry. Finally, an experiment to observe pressure drop with long-term particle loading was carried out. In the experiments with the monodisperse aerosol, no penetration was observed regardless of particle size. Therefore, face velocity was increased and high concentrations of the polydisperse aerosol were used to increase the penetration. The MPPS was then found to be 333 and 250 nm at a flowrate of 10 and 40 L/min, respectively. The MPPS model for diffusion and interception dominant regime proposed by Lee and Liu (1986) was closest to these results. Dimensionless permeability varied depending on the conditions for which the individual models were derived. For example, the RUC (representative unit cell) model underestimates the results while the results predicted using the empirical formula of Davies (1953) differ significantly from the measured values. The loading experiments have shown significantly prolonged fouling by high concentrations of submicron particles compared to conventional fibrous filters.

Morphology tuning of inorganic nanomaterials grown by precipitation through control of electrolytic dissociation and supersaturation

The precise control of the morphology of inorganic materials during their synthesis is important yet challenging. Here we report that the morphology of a wide range of inorganic materials, grown by rapid precipitation from a metal cation solution, can be tuned during their crystallization from one- to three-dimensional (1D to 3D) structures without the need for capping agents or templates. This control is achieved by adjusting the balance between the electrolytic dissociation (α) of the reactants and the supersaturation (S) of the solutions. Low-α, weak electrolytes promoted the growth of anisotropic (1D and 2D) samples, with 1D materials favoured in particular at low S. In contrast, isotropic 3D polyhedral structures could only be prepared in the presence of strong electrolyte reactants (α ≈ 1) with low S. Using this strategy, a wide range of materials were prepared, including metal oxides, hydroxides, carbonates, molybdates, oxalates, phosphates, fluorides and iodate with a variety of morphologies.

Robust 3D image reconstruction of pancreatic cancer tumors from histopathological images with different stains and its quantitative performance evaluation

PurposeHistopathological imaging is widely used for the analysis and diagnosis of multiple diseases. Several methods have been proposed for the 3D reconstruction of pathological images, captured from thin sections of a given specimen, which get nonlinearly deformed due to the preparation process. The majority of the available methods for registering such images use the degree of matching of adjacent images as the criteria for registration, which can result in unnatural deformations of the anatomical structures. Moreover, most methods assume that the same staining is used for all images, when in fact multiple staining is usually applied in order to enhance different structures in the images.MethodsThis paper proposes a non-rigid 3D reconstruction method based on the assumption that internal structures on the original tissue must be smooth and continuous. Landmarks are detected along anatomical structures using template matching based on normalized cross-correlation (NCC), forming jagged shape trajectories that traverse several slices. The registration process smooths out these trajectories and deforms the images accordingly. Artifacts are automatically handled by using the confidence of the NCC in order to reject unreliable landmarks.ResultsThe proposed method was applied to a large series of histological sections from the pancreas of a KPC mouse. Some portions were dyed primarily with HE stain, while others were dyed alternately with HE, CK19, MT and Ki67 stains. A new evaluation method is proposed to quantitatively evaluate the smoothness and isotropy of the obtained reconstructions, both for single and multiple staining.ConclusionsThe experimental results show that the proposed method produces smooth and nearly isotropic 3D reconstructions of pathological images with either single or multiple stains. From these reconstructions, microanatomical structures enhanced by different stains can be simultaneously observed.

Three-Dimensional Optical Anisotropy of Low-Symmetry Layered GeS.

In-plane anisotropic two-dimensional (2D) materials, especially black phosphorus and ReS2, have attracted significant interest recently as they can provide one more dimension to manipulate their physical properties when compared with isotropic 2D materials. As a representative anisotropic 2D material, germanium monosulfide (GeS) has emerged as a new research hot topic in this field because of its unique in-plane anisotropic physical properties. Despite the rapid growing progress in the study of GeS, many of their fundamental optical anisotropies are still absent. Here, we report the three-dimensional (3D) optical anisotropy of GeS from theory to experiment. The 3D optical anisotropic properties including extinction, refraction, absorption, and reflection were systematically investigated through density functional calculations. The anisotropic refraction and reflection of GeS were experimentally verified by polarization-resolved optical microscopy and azimuth-dependent reflectance difference microscopy, respectively. Finally, a GeS-based linear dichroic photodetector was demonstrated with a dichroic ratio of 1.45 because of its polarization sensitive absorption. Our results provide deep insights into the optical anisotropy of GeS, which is important for the further development of GeS-based optoelectronic and optical devices.

Free-running 3D whole heart myocardial T1 mapping with isotropic spatial resolution.

PurposeTo develop a free‐running (free‐breathing, retrospective cardiac gating) 3D myocardial T1 mapping with isotropic spatial resolution.MethodsThe free‐running sequence is inversion recovery (IR)‐prepared followed by continuous 3D golden angle radial data acquisition. 1D respiratory motion signal is extracted from the k‐space center of all spokes and used to bin the k‐space data into different respiratory states, enabling estimation and correction of 3D translational respiratory motion, whereas cardiac motion is recorded using electrocardiography and synchronized with data acquisition. 3D translational respiratory motion compensated T1 maps at diastole and systole were generated with 1.5 mm isotropic spatial resolution with low‐rank inversion and high‐dimensionality patch‐based undersampled reconstruction. The technique was validated against conventional methods in phantom and 9 healthy subjects.ResultsPhantom results demonstrated good agreement (R2 = 0.99) of T1 estimation with reference method. Homogeneous systolic and diastolic 3D T1 maps were reconstructed from the proposed technique. Diastolic septal T1 estimated with the proposed method (1140 ± 36 ms) was comparable to the saturation recovery single‐shot acquisition (SASHA) sequence (1153 ± 49 ms), but was higher than the modified Look‐Locker inversion recovery (MOLLI) sequence (1037 ± 33 ms). Precision of the proposed method (42 ± 8 ms) was comparable to MOLLI (41 ± 7 ms) and improved with respect to SASHA (87 ± 19 ms).ConclusionsThe proposed free‐running whole heart T1 mapping method allows for reconstruction of isotropic resolution 3D T1 maps at different cardiac phases, serving as a promising tool for whole heart myocardial tissue characterization.

Magnetic field driven critical behavior in bulk Gd

Gadolinium (Gd) has been proven to be such a complex magnetic system that its static universality class varies as a function of the reduced temperature (|ɛ| = |T−TC|/TC). Though many works have been done, physical mechanisms of this phenomenon have not been fully elucidated. In this work, we analyzed the static magnetization data, M(H), around the ferromagnetic-paramagnetic phase transition temperature (TC) based on Banerjee's criteria, the modified Arrott plot and Kouvel–Fisher techniques, the critical isotherm analysis, and the scaling hypothesis to reconsider the phase transition, magnetic order, and isotropic and uniaxial behaviors of a polycrystalline Gd bulk. The M(H) data analyses with H variations up to 140 kOe indicated that Gd still keeps the nature of a second-order phase transition and short-range magnetic order. In the critical region of |ɛ| = 3.4 × 10−3–6.9 × 10−2, we observed the critical-behavior transition from a mixed isotropic and uniaxial ferromagnet for H = 3–10 kOe through an isotropic 3D Heisenberg ferromagnet for H = 10–100 kOe to a uniaxial 3D Ising ferromagnet for H = 100–140 kOe. The results demonstrate the possibility of using high fields to identify the universality class of Gd. The fluctuations and preferred reorientation of spins in the hexagonal close-packed lattice at temperatures T > 230 K are thought to cause these interesting phenomena.

Measuring Liquid Drop Properties on Nanoscale 1D Patterned Photoresist Structures

This communication reports liquid wetting properties of DI-water on one-dimensional nano-patterned photoresist lines atop a silicon substrate as the pattern period is varied from 0.3- to 1.0-µm. Both constant photoresist height and constant width/height ratios are investigated. The line/period ratio was fixed at 0.3 (0.4) for different measurement sequences. The surface of the photoresist was treated with a short CHF3 reactive ion etch to ensure consistent hydrophobic photoresist: water surface energies. Average parallel contact angle (θ||), average perpendicular contact angle (θ⊥), drop width (W), and drop length (L) at constant volume were measured on nano-patterned surfaces fabricated with interferometric lithography. Both θ|| and θ⊥ contact angles increase as the period (0.3- to 1-μm) increases; the θ|| spreading rate is faster than θ⊥ due to pinning on the grooves resulting in an elongated drop shape. The traditional Wenzel and Cassie-Baxter models of drop contact angles were developed for isotropic random 2D roughness and do not account for the anisotropy induced by the 1D line patterns. The observed angular variations with period are not consistent with either model. Understanding liquid wetting properties and hydrophobicity on 1D silicon surfaces has many applications in lab-on-a-chip, micro/nano-fluidic devices, roll-to-roll nano-imprint fabrication, self-cleaning surfaces, and micro-reactors.

Fetal MRI and prenatal diagnosis of congenital heart defects

Fetal MRI and prenatal diagnosis of congenital heart defects

Three-dimensional visualisation of the fetal heart using prenatal MRI with motion-corrected slice-volume registration: a prospective, single-centre cohort study

SummaryBackgroundTwo-dimensional (2D) ultrasound echocardiography is the primary technique used to diagnose congenital heart disease before birth. There is, however, a longstanding need for a reliable form of secondary imaging, particularly in cases when more detailed three-dimensional (3D) vascular imaging is required, or when ultrasound windows are of poor diagnostic quality. Fetal MRI, which is well established for other organ systems, is highly susceptible to fetal movement, particularly for 3D imaging. The objective of this study was to investigate the combination of prenatal MRI with novel, motion-corrected 3D image registration software, as an adjunct to fetal echocardiography in the diagnosis of congenital heart disease.MethodsPregnant women carrying a fetus with known or suspected congenital heart disease were recruited via a tertiary fetal cardiology unit. After initial validation experiments to assess the general reliability of the approach, MRI data were acquired in 85 consecutive fetuses, as overlapping stacks of 2D images. These images were then processed with a bespoke open-source reconstruction algorithm to produce a super-resolution 3D volume of the fetal thorax. These datasets were assessed with measurement comparison with paired 2D ultrasound, structured anatomical assessment of the 2D and 3D data, and contemporaneous, archived clinical fetal MRI reports, which were compared with postnatal findings after delivery.FindingsBetween Oct 8, 2015, and June 30, 2017, 101 patients were referred for MRI, of whom 85 were eligible and had fetal MRI. The mean gestational age at the time of MRI was 32 weeks (range 24–36). High-resolution (0·50–0·75 mm isotropic) 3D datasets of the fetal thorax were generated in all 85 cases. Vascular measurements showed good overall agreement with 2D echocardiography in 51 cases with paired data (intra-class correlation coefficient 0·78, 95% CI 0·68–0·84), with fetal vascular structures more effectively visualised with 3D MRI than with uncorrected 2D MRI (657 [97%] of 680 anatomical areas identified vs 358 [53%] of 680 areas; p<0·0001). When a structure of interest was visualised in both 2D and 3D data (n=358), observers gave a higher diagnostic quality score for 3D data in 321 (90%) of cases, with 37 (10%) scores tied with 2D data, and no lower scores than for 2D data (Wilcoxon signed rank test p<0·0001). Additional anatomical features were described in ten cases, of which all were confirmed postnatally.InterpretationStandard fetal MRI with open-source image processing software is a reliable method of generating high-resolution 3D imaging of the fetal vasculature. The 3D volumes produced show good spatial agreement with ultrasound, and significantly improved visualisation and diagnostic quality compared with source 2D MRI data. This freely available combination requires minimal infrastructure, and provides safe, powerful, and highly complementary imaging of the fetal cardiovascular system.FundingWellcome Trust/EPSRC Centre for Medical Engineering, National Institute for Health Research.

MRI of Uveal Melanoma.

Uveal Melanoma (UM) is the most common primary malignant ocular tumor. The high soft tissue contrast and spatial resolution, and the possibility of generating 3D volumetric and functional images, make Magnetic Resonance Imaging (MRI) a valuable diagnostic imaging technique in UM. Current clinical MRI protocols, however, are not optimized for UM and therefore lack the quality for accurate assessments. We therefore developed a dedicated protocol at a 3 Tesla MRI, using an eye coil, consisting of multi-slice 2D sequences, different isotropic sequences and diffusion and perfusion-weighted images. This protocol was prospectively evaluated in 9 uveal melanoma patients. The multi-slice 2D sequences had the highest in-plane resolution, being the most suited for lesion characterization and local extension evaluation. The isotropic 3D Turbo-Spin Echo (TSE) sequences were the most suitable for accurate geometric measurements of the tumor and are therefore important for therapy planning. Diffusion and perfusion-weighted images aid in differentiating benign from malignant lesions and provide quantitative measures on tumor hemodynamics and cellularity, which have been reported to be effective in predicting and assessing treatment outcome. Overall, this dedicated MRI protocol provides high-quality imaging of UM, which can be used to improve its diagnosis, treatment planning, and follow-up.

Influence of mixed isotropic fiber angles and hot press on the mechanical properties of 3D printed composites

This paper aims to study the mechanical properties of mixed isotropic carbon fiber 3D printed composites and further investigates the influence of hot press on the [0°/45°/90°]2 fiber angles composite with varying temperature, pressure and time. Tensile tests, autoclave treatment and microstructural observation were utilized to characterize the composites. Results revealed that the [0°/45°/90°]2 performed the highest tensile strength of 79 MPa and modulus of 3.51 GPa, compared to [30°/45°/60°]2 and [15°/45°/75°]2. This is due to the fibers along the tensile axis angle that bears maximum load in longitudinal direction. At 200 °C temperature, the hot pressed composites presented the highest tensile strength of 98 MPa and modulus of 3.93 GPa than non-hot pressed. Increased temperature caused better interface wettability between fibers and matrix. At 200 kPa pressure, the hot pressed composites showed the highest tensile strength of 100 MPa and modulus of 4.06 GPa than non-hot pressed. Further increased pressure resulted in lower tensile strength and modulus, as the material became stiffer pushing more matrix material to side leaving numerous fibers unbounded by the matrix. For 30 min withholding time, the hot pressed composites indicated the highest tensile strength of 106 MPa and modulus of 4.27 GPa than non-hot pressed. Increased time caused strongest interface bonding by removing the air gaps induced during printing between fibers and matrix. Results revealed that hot press significantly improved the mechanical properties of carbon fiber 3D printed composites.

10-MINUTE 3D MRI IN CHILDREN WITH ACUTE KNEE TRAUMA: ARTHROSCOPY-BASED DIAGNOSTIC ACCURACY FOR THE DIAGNOSIS OF INTERNAL DERANGEMENT

Background Magnetic resonance imaging (MRI) is often indicated in the diagnosis of pediatric knee trauma, but using traditional MRIs in children can be time-consuming, require anaesthesia, and sometimes cause discomfort. Recently, 3D turbo spin echo (TSE) MRIs with isotropic datasets have been found to reduce acquisition times substantially, but they have been little-studied in pediatric patients. The purpose of our study was to determine the arthroscopy-based diagnostic performance of 10-minute isotropic 3D TSE MRI for the detection of internal derangement in children with acute knee trauma. Methods Institutional review board approval was obtained for prospective data collection, and informed consent and assent were obtained from all parents and children, respectively. The final study group consisted of 60 children (38 boys, 22 girls; 11 (2-16) years-of-age) with acute knee trauma who underwent 10-minute isotropic 3D prototype CAIPIRINHA SPACE MRI at 3 T and subsequent arthroscopic knee surgery. Two fellowship-trained musculoskeletal radiologists retrospectively evaluated the MRI studies independently and resolved discrepancies through consensus. Outcome variables included image quality, motion artifacts, meniscal abnormalities, cruciate ligament tears, and cartilage lesions. Statistical analysis included the diagnostic performance of MRI with arthroscopy as the reference standard and inter-reader agreements using kappa statistics. Results All studies were suitable for diagnostic interpretation with good-to-very-good image quality and little-to-no motion degradation in the majority of cases. The sensitivities/specificities/accuracies of MRI were 0.93/0.93/0.93 for 15/60 (25%) medial meniscal tears, 0.95/0.90/0.92 for 21/60 (35%) lateral meniscal tears, 0.83/1.0/0.92 for 10/60 (17%) discoid menisci, 1.0/0.95/0.98 for 16/60 (27%) anterior cruciate ligament tears, 1.0/0.95/0.98 for 2/60 (3%) posterior cruciate ligament tears, 1.0/1.0/1.0 for 5/60 (8%) osteochondritis dissecans lesions, and 0.71/0.97/0.84 for 48 (13%) defects in 360 cartilage segments. The inter-reader agreements were overall good-to-very-good (kappa, 0.730 -1.00). Conclusion 10-minute isotropic 3D TSE MRI of the knee is feasible in children with acute knee trauma and yields high diagnostic accuracies for the diagnosis of internal knee derangement. Accuracies for the detection of meniscal tears, discoid menisci, anterior and posterior cruciate ligament tears, osteochondritis dissecans lesions, and cartilage defects ranged from 84-100%. Using previously published protocols for pediatric 2D MRI knee exams with total acquisition times of 25 minutes as a benchmark for traditional MRI, a 10-minute protocol could increase the efficiency by a factor of two or more, and thus substantially improve the availability of MRI and timely care for children with acute knee trauma. [Table: see text]

Emerging in‐plane anisotropic two‐dimensional materials

AbstractBlack phosphorus (BP) is a rapidly up and coming star in two‐dimensional (2D) materials. The unique characteristic of BP is its in‐plane anisotropy. This characteristic of BP ignites a new type of 2D materials that have low‐symmetry structures and in‐plane anisotropic properties. On this basis, they offer richer and more unique low‐dimensional physics compared to isotropic 2D materials, thus providing a fertile ground for novel applications including electronics, optoelectronics, molecular detection, thermoelectric, piezoelectric, and ferroelectric with respect to in‐plane anisotropy. This article reviews the recent advance in characterization and applications of in‐plane anisotropic 2D materials.

Two-Dimensional Electronic Transport in Rubrene: The Impact of Inter-Chain Coupling.

Organic semi-conductors have unique electronic properties and are important systems both at the fundamental level and also for their applications in electronic devices. In this article we focus on the particular case of rubrene which has one of the best electronic transport properties for application purposes. We show that this system can be well simulated by simple tight-binding systems representing one-dimensional (1D) chains that are weakly coupled to their neighboring chains in the same plane. This makes in principle this rubrene system somehow intermediate between 1D and isotropic 2D models. We analyse in detail the dc-transport and terahertz conductivity in the 1D and in the anisotropic 2D models. The transient localisation scenario allows us to reproduce satisfactorily some basics results such as mobility anisotropy and orders of magnitude as well as ac-conductivity in the terahertz range. This model shows in particular that even a weak inter-chain coupling is able to improve notably the propagation along the chains. This suggest also that a strong inter-chain coupling is important to get organic semi-conductors with the best possible transport properties for applicative purposes.

Artificial control of in-plane anisotropic photoelectricity in monolayer MoS2

Intrinsic linear polarized optics discovered in anisotropic two-dimensional (2D) materials has attracted intense interest for polarization-sensitive optical and optoelectronic applications, such as black phosphorous, ReSe2, etc. However, the lack of matured method to synthesize high-quality, large-scale and air-stable 2D materials with anisotropic properties, is still an obstacle for practical applications. Monolayer molybdenum disulfide (MoS2), which exhibits strong direct-band-gap light-harvesting properties, can be grown maturely. But unfortunately, MoS2 does not show linear dichroism owing to its in-plane isotropic crystalline symmetry. We, herein, for the first time, report on an artificial control of extrinsic linear polarized photoelectric effect in monolayer MoS2, by successfully controlling its anisotropic degree of in-plane crystal symmetry via artificially induced uniaxial tensile strain. Strong linear polarization-sensitive photodetection from visible to near-infrared range is realized for monolayer MoS2-based device, and the polarization anisotropic ratio can reach up over 2.0 under 4.5% strain. The observation is supported by combination of experiment-theory study on polarized Raman spectrum and optical absorption under gradually applied strains. Our results have demonstrated that the artificial-controlled symmetry reducing of MoS2 is a promising strategy to achieve high performance polarization photodetection. This method can also be extended to other 2D materials, which potentially opens up a new field to endow isotropic 2D materials with anisotropic functionalities by artificial structure engineering.

3D Heteroatom-Doped Carbon Nanomaterials as Multifunctional Metal-Free Catalysts for Integrated Energy Devices.

Sustainable and cost-effective energy generation has become crucial for fulfilling present energy requirements. For this purpose, the development of cheap, scalable, efficient, and reliable catalysts is essential. Carbon-based heteroatom-doped, 3D, and mesoporous electrodes are very promising as catalysts for electrochemical energy conversion and storage. Various carbon allotropes doped with a variety of heteroatoms can be utilized for cost-effective mass production of electrode materials. 3D porous carbon electrodes provide multiple advantages, such as large surface area, maximized exposure to active sites, 3D conductive pathways for efficient electron transport, and porous channels to facilitate electrolyte diffusion. However, it is challenging to synthesize and functionalize isotropic 3D carbon structures. Here, various synthesis processes of 3D porous carbon materials are summarized to understand how their physical and chemical properties together with heteroatom doping dictate the electrochemical catalytic performance. Prospects of attractive 3D carbon structural materials for energy conversion and efficient integrated energy systems are also discussed.