Ultrafast Laser‐Shock‐Induced Confined Metaphase Transformation for Direct Writing of Black Phosphorus Thin Films

Few‐layer black phosphorus (BP) has emerged as one of the most promising candidates for post‐silicon electronic materials due to its outstanding electrical and optical properties. However, lack of large‐scale BP thin films is still a major roadblock to further applications. The most widely used methods for obtaining BP thin films are mechanical exfoliation and liquid exfoliation. Herein, a method of directly synthesizing continuous BP thin films with the capability of patterning arbitrary shapes by employing ultrafast laser writing with confinement is reported. The physical mechanism of confined laser metaphase transformation is understood by molecular dynamics simulation. Ultrafast laser ablation of BP layer under confinement can induce transient nonequilibrium high‐temperature and high‐pressure conditions for a few picoseconds. Under optimized laser intensity, this process induces a metaphase transformation to form a crystalline BP thin film on the substrate. Raman spectroscopy, atomic force microscopy, and transmission electron microscopy techniques are utilized to characterize the morphology of the resulting BP thin films. Field‐effect transistors are fabricated on the BP films to study their electrical properties. This unique approach offers a general methodology to mass produce large‐scale patterned BP films with a one‐step manufacturing process that has the potential to be applied to other 2D materials.     

Asymmetric 3D Elastic–Plastic Strain‐Modulated Electron Energy Structure in Monolayer Graphene by Laser Shocking

Graphene has a great potential to replace silicon in prospective semiconductor industries due to its outstanding electronic and transport properties; nonetheless, its lack of energy bandgap is a substantial limitation for practical applications. To date, straining graphene to break its lattice symmetry is perhaps the most efficient approach toward realizing bandgap tunability in graphene. However, due to the weak lattice deformation induced by uniaxial or in‐plane shear strain, most strained graphene studies have yielded bandgaps <1 eV. In this work, a modulated inhomogeneous local asymmetric elastic–plastic straining is reported that utilizes GPa‐level laser shocking at a high strain rate (dε/dt) ≈ 10⁶–10⁷ s^?1, with excellent formability, inducing tunable bandgaps in graphene of up to 2.1 eV, as determined by scanning tunneling spectroscopy. High‐resolution imaging and Raman spectroscopy reveal strain‐induced modifications to the atomic and electronic structure in graphene and first‐principles simulations predict the measured bandgap openings. Laser shock modulation of semimetallic graphene to a semiconducting material with controllable bandgap has the potential to benefit the electronic and optoelectronic industries.     

Empirical study of hearsay rules: Bridging the gap between psychology and law.

The legal rules regarding hearsay rest heavily on "empirical hunches" that could usefully be evaluated through psychological research. Because of the complexity of the rules, psychologists have found it difficult to identify important underlying assumptions that might be tested and lawyers have not appreciated the possible importance of empirical research. This article is designed to help bridge the gap between psychology and law by promoting innovative thinking about the role of empirical research in the evaluation of hearsay. The authors describe the hearsay rules and their rationale in a manner useful to psychological researchers and discuss the prospects for testing underlying assumptions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

From child to witness to jury: Effects of suggestion on the transmission and evaluation of hearsay.

Two interlocking experiments simulated the transmission of hearsay from children to adult hearsay witnesses and from the hearsay witnesses to jurors. Thirty-one children (ages 5–6 years) each observed a janitor either clean or play with toys in a laboratory. Each child was interrogated about the janitor in either a neutral manner that elicited an accurate account or a suggestive manner that elicited an inaccurate account of what the janitor had done. In Experiment 1, adult "witnesses" (N?=?112) each observed one of these interrogations and then recounted what the child had said. In Experiment 2, a 2nd group of adults in the role of jurors (N?=?104) each heard the account of one of the hearsay witnesses then made judgments about what the janitor had done. Jurors were sensitive to the quality of the hearsay evidence. They gave no weight to hearsay that recounted the inaccurate statements of a child who was questioned suggestively but gave appropriate weight to hearsay that recounted the accurate statements of children questioned in a neutral manner. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Purification,characterisation and kinetics of a trypsin inhibitor from black gram (Vigna mungo)

A black gram (Vigna mungo) trypsin inhibitor (BGTI) was purified to homogeneity by ammonium sulphate precipitation, DEAE-cellulose chromatography and affinity chromatography. The homogeneity of the inhibitor was identified by polyacrylamide gel electrophoresis (PAGE), SDS–PAGE, immunodiffusion and immunoelectrophoresis. The isoelectric point of BGTI was 8.32. The molecular weight of the BGTI was found to be about 12500 by both gel filtration and SDS–PAGE. One mole of the BGTI was found to contain 75 amino acid residues, and it was identified as a glycoprotein, comprising about 18.2% carbohydrate. The BGTI was an uncompetitive inhibitor, stable in the pH range 2–10 and in the temperature range 30–80°C for 30 min.     

Large‐Area Direct Laser‐Shock Imprinting of a 3D Biomimic Hierarchical Metal Surface for Triboelectric Nanogenerators

Ongoing efforts in triboelectric nanogenerators (TENGs) focus on enhancing power generation, but obstacles concerning the economical and cost‐effective production of TENGs continue to prevail. Micro‐/nanostructure engineering of polymer surfaces has been dominantly utilized for boosting the contact triboelectrification, with deposited metal electrodes for collecting the scavenged energy. Nevertheless, this state‐of‐the‐art approach is limited by the vague potential for producing 3D hierarchical surface structures with conformable coverage of high‐quality metal. Laser‐shock imprinting (LSI) is emerging as a potentially scalable approach for directly surface patterning of a wide range of metals with 3D nanoscale structures by design, benefiting from the ultrahigh‐strain‐rate forming process. Here, a TENG device is demonstrated with LSI‐processed biomimetic hierarchically structured metal electrodes for efficient harvesting of water‐drop energy in the environment. Mimicking and transferring hierarchical microstructures from natural templates, such as leaves, into these water‐TENG devices is effective regarding repelling water drops from the device surface, since surface hydrophobicity from these biomicrostructures maximizes the TENG output. Among various leaves' microstructures, hierarchical microstructures from dried bamboo leaves are preferable regarding maximizing power output, which is attributed to their unique structures, containing both dense nanostructures and microscale features, compared with other types of leaves. Also, the triboelectric output is significantly improved by closely mimicking the hydrophobic nature of the leaves in the LSI‐processed metal surface after functionalizing it with low‐surface‐energy self‐assembled‐monolayers. The approach opens doors to new manufacturable TENG technologies for economically feasible and ecologically friendly production of functional devices with directly patterned 3D biomimic metallic surfaces in energy, electronics, and sensor applications.     

Scalable Nanoshaping of Hierarchical Metallic Patterns with Multiplex Laser Shock Imprinting Using Soft Optical Disks

Large‐area patterning of metals in nanoscale has always been a challenge. Traditional microfabrication processes involve many high‐cost steps, including etching and high‐vacuum deposit, which limit the development of functional nanostructures, especially multiscale metallic patterns. Here, multiplex laser shock imprinting (MLSI) process is introduced to directly manufacture hierarchical micro/nanopatterns at a high strain rate on metallic surfaces using soft optical disks with 1D periodic trenches as molds. The unique metal/polymer layered structures in inexpensive soft optical disks make them strong candidates of molds for MLSI processes. The feasibility of MLSI on hard metals toward soft molds is studied using theoretical simulation. In addition, various types of hierarchical structures are fabricated via MLSI, and their optical reflectance can be modulated via a combination of depth (laser power density), width (types of molds), and angles (rotation between molds). The optical properties have been studied with surface plasmon polariton modes theory. This work opens a new way of manufacturing hierarchical micro/nanopatterns on metals, which is promising for future applications in fields of plasmonics and metasurfaces.     

Studies on black gram (Vigna mungo) trypsin inhibitor

The trypsin inhibitor fraction from black gram was isolated by ammonium sulphate fractionation (0-75%). It exerted maximum inhibition on trypsin and to a less extent on the endopeptidases, chymotrypsin, papain, pronase and pepsin in vitro, In-vitro digestibility of the raw black gram was found to be lower than autoclaved black gram and autoclaved black gram supplemented with native black gram trypsin inhibitor. Haemagglutinating activity was absent in the black gram extract as well as in the black gram trypsin inhibitor fractions. During the last 48 h of germination there was a steep decline in trypsin inhibitory activity and an increase was observed later. Trypsin inhibitory activity was greater in the leaves than the cotyledons during the fourth, fifth and sixth days of germination.