Strip-like Structure Research Articles

InstaCropNet: An efficient Unet-Based architecture for precise crop row detection in agricultural applications

Autonomous navigation in farmlands is one of the key technologies for achieving autonomous management in maize fields. Among various navigation techniques, visual navigation using widely available RGB images is a cost-effective solution. However, current mainstream methods for maize crop row detection often rely on highly specialized, manually devised heuristic rules, limiting the scalability of these methods. To simplify the solution and enhance its universality, we propose an innovative crop row annotation strategy. This strategy, by simulating the strip-like structure of the crop row's central area, effectively avoids interference from lateral growth of crop leaves. Based on this, we developed a deep learning network with a dual-branch architecture, InstaCropNet, which achieves end-to-end segmentation of crop row instances. Subsequently, through the row anchor segmentation technique, we accurately locate the positions of different crop row instances and perform line fitting. Experimental results demonstrate that our method has an average angular deviation of no more than 2°, and the accuracy of crop row detection reaches 96.5%.

Fabrication of thermally resistant and mechanically flexible polyimide foams with anisotropic pore structures for thermal insulation and irradiation tolerance applications

Flexible polyimide foams (PIFs) demonstrate a great potential for applications in the fields of thermal insulation, flame retardancy and irradiation tolerance. In this work, mechanically flexible PIFs with anisotropic pore structure were prepared by adopting the copolymerization strategy and microwave-assisted foaming process. The copolymerization reaction was conducted to synthesize polyester ammonium salt (PEAS) precursors using 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA) as dianhydride, 4,4′-diaminodiphenyl ether (ODA) and 4,4′-diaminodiphenyl sulfone (DDS) as the copolymerized diamines; afterwards, PEAS powders with particle sizes ranging from 100 to 300 μm were obtained by drying, crushing and sieving treatments, which were used as the feedstock for “bottom-up” microwave-assisted foaming and thermal imidization process, thereby leading to the formation of PIFs with regular three-dimensional near-spherical pores in vertical direction (parallel to the pore growth direction) and the aligned ellipsoidal strip-like pore structure in horizontal direction. The directional growth of foam pores resulted in anisotropic mechanical flexibility and thermal insulation performance. Moreover, PIFs possessed excellent thermal stability and flame retardancy with the initial thermal degradation temperature higher than 545 °C and limited oxygen index up to 58.8%. The PIFs exhibited exceptional thermal insulation performance with thermal conductivity values ranging from 0.0276 to 0.0517 W/(m·K) between 25 and 300 °C. Additionally, the PIFs demonstrated excellent irradiation tolerance, with the mechanical and thermal stability retention rate being above 96% after the irradiation experiment (radiation dosage: 1.15 × 105 Gy) using 60Co source. Thus, lightweight PIFs with superior high temperature thermal insulation performance, flame retardancy and irradiation tolerance were successfully prepared, which showed potential applications in aerospace, medical and nuclear power sectors.

REMAINS OF THE ALIMENTARY TRACT IN THE LATE ORDOVICIAN TRILOBITE <em>DALMANITINA</em> (PRAGUE BASIN, BARRANDIAN AREA, CZECH REPUBLIC)

Preservation of digestive structures in trilobites is generally rare; remains of the alimentary tract have been documented in about eighty of more than twenty thousand described species. Several tens of specimens belonging to five Cambrian and nine Ordovician species from the Barrandian area, Czech Republic, have markedly contributed to the knowledge of the trilobite digestive system. Here, we describe seven exceptionally preserved late holaspid trilobite specimens of species of the genus Dalmanitina collected from Upper Ordovician strata of the Barrandian area. All studied specimens are preserved as internal moulds and exhibit a narrow strip-like structure that runs sagitally or sub-sagitally under the axial lobe of the thoracopygon. These strip-like structures are markedly different from scavenger burrows and are interpreted as remains of the alimentary canal. A slightly expanded anterior-most part of the digestive system is preserved in the cephalic shield of six specimens and is interpreted as a remainder of the anterior midgut. A dark area is seen in the glabellar lobes of three specimens. These dark areas do not represent pyrite concentrations in the hypostome–glabellar cavity, because they contain only small amounts of Fe and S. These areas are interpreted as the remainder of cephalic digestive midgut diverticula, or the “perigastric organ”. Quantitative chemical analyses show that in species of Dalmanitina the digestive system is preserved as dark matter containing partly digested food particles and most probably also a higher amount of clay minerals. The described specimens constitute the first well-documented example of digestive structures in the subfamily Dalmanitininae.

Fabrication of flexible polyimide/rGO composite foams and their derived carbon foams for thermal insulation and EMI shielding applications

In this work, a facile microwave-assisted foaming and thermal imidization treatment method was proposed to fabricate flexible polyimide (PI)/rGO composite foams with anisotropic pore structures. The PI/rGO composite foams (PIF/rGO) were used as the starting derivatives to prepare carbon foams that demonstrated excellent anisotropic thermal insulation and electromagnetic interference (EMI) shielding applications. The directional growth of pore structures during the foaming period resulted in the formation of aligned ellipsoidal strip-like pore structure in the horizontal direction (i.e., perpendicular to the pore growth direction), which was attributed to the escape of foaming gases such as tetrahydrofuran, methanol and H2O. The homogeneous dispersion of rGO in the PI-derived carbon skeleton endowed corresponding carbon foams with excellent mechanical and thermal stability, high thermal insulation and electrical conductivity (σ) as well as absorption dominated EMI shielding performance. The σ and EMI shielding effectiveness (SE) of carbon foams showed an increasing trend with increasing rGO content. The σ, EMI SE and specific EMI SE of the carbon foams reached up to 33.0 S/m, 49.0 dB and 8792.8 dB/(g/cm2) in the horizontal direction, respectively. Therefore, this work provided a facile strategy to fabricate lightweight and anisotropic pore structure rGO-containing PIFs and carbonized derivatives, which demonstrated promising applications in high-end industrial fields.

Multimodal Self-sustainable Autonomous Locomotions of Light-driven Seifert Ribbon Actuators based on Liquid Crystal Elastomers.

Multimodal self-sustainable autonomous locomotions integrated into one individual system, are high-level intelligent behavioral characteristics of living organisms and are the scientific hotspot of bionic soft actuators. Here, we report a light-fueled soft actuator with multimodal self-sustainable movements based on a Seifert ribbon bounded by a Hopf link. The Seifert ribbon actuator can self-sense the illumination area adjustment, and the actuation component becomes either a discontinuous strip-like structure or a continuous toroidal structure, which can realize adaptive switches between self-sustained oscillatory and rotary motions. The two motion modes are applied to the self-oscillatory piezoelectric generation and self-rotational work multiplication of cargo transport, respectively. The unique smartness of Seifert surface topology advances the level of actuation intelligence with broad implications for the adaptability, multifunctionality, and autonomy of soft robots.

Effects of methacrylic anhydride gelatin hydrogel loaded with silver and recombinant human basic fibroblast growth factor on deep partial-thickness burn wounds in rabbits

Effects of methacrylic anhydride gelatin hydrogel loaded with silver and recombinant human basic fibroblast growth factor on deep partial-thickness burn wounds in rabbits

Highly Oriented {010} Crystal Plane Induced by Boron in Cobalt-Free Li- and Mn-Rich Layered Oxide.

Li- and Mn-rich layered oxide (LMR) materials are a promising candidates for next-generation Li-ion battery (LIB) anode materials because of their high specific capacity. However, their low initial Coulombic efficiency, voltage decay, and irreversible phase transition during cycling are the fatal drawbacks of LMR materials. This work reports on a cobalt-free LMR material composed of primary particles with a boron-induced exposed long- strip-like {010} plane. Because of this unique structure, the long strip-like cathode exhibits excellent electrochemical performance with a discharge capacity of 202 mAh g-1 at 1 C and a retention rate of 95.2% after 200 cycles. In addition, it is found that this long strip-like structure can modulate the redox of oxygen and enhance the reversibility. The irreversible phase transition process from the layered to a spinel and then to a rock-salt phase during cycling is also significantly suppressed. This work provides a feasible method for regulating the exposed {010} plane and a new idea for the structural design of LMR materials.

UWB MIMO ANTENNA DESIGN AND FABRICATION WITH PROTRUDED STUB BASED ISOLATION

A compact planar closely placed ultra-wideband circular-patch antenna with multiple-input/multiple-output technology is discussed in this paper. A complementary split-ring resonator structure was introduced between the antennas and a protruded strip-like structure was added to the antenna itself to improve the isolation between the antennas. The defected ground structure was used to further improve the S-parameters. Slots were introduced in the antenna structure to improve the bandwidth. A FR-4 substrate was used in the simulations. The overall cross section of the antenna was 16 × 26 mm<sup>2</sup>. The antenna was simulated using the computer simulation technology software program, CST Studio Suite. In this paper, several antenna parameters are also discussed, such as voltage standing wave ratio (VSWR), gain, envelope correlation coefficient (ECC), radiation pattern, and various other characteristic parameters. The proposed design resonates at 5.34, 8.63, 9.8, and 10.48 GHz with return losses of -33.5, -28.3, -51.9, and -43 dB, respectively. In addition, it has a bandwidth of 4.33-11.419 GHz, an ECC close to zero throughout the band, and has VSWR of less than 1.6 throughout the band.

Magnonic Crystal with Strips of Magnetic Nanoparticles: Modeling and Experimental Realization via a Dip-Coating Technique

In this article, we describe a magnonic crystal formed by magnetite nanoparticles. The periodic strip-like structure of the nanoparticles was fabricated on the surface of thin yttrium iron garnet single-crystal film grown on a gallium–gadolinium garnet substrate via dip-coating techniques. It was shown that such periodic structure induces the formation of the bandgaps in the transmission spectra of magnetostatic surface spin-waves (MSSW). The structure was simulated by the transfer matrix method. Spin-wave detection has been carried out by using a pair of microwave antennas and a vector network analyzer.

Controllable Modulation to Quantum Well States on β-Sn IslandsSupported by the National Natural Science Foundation of China (Grant Nos. 11521404, 11634009, 11674222, 11674226, 11790313, 11574202, 11874256, U1632102, 11861161003 and 11874258), the National Key Research and Development Program of China (Grant Nos. 2016YFA0300403 and 2016YFA0301003), the Key Research Program of the Chinese Academy of Sciences (Grant No. XDPB08-2), the Strategic Priority

We investigate the surface structure and electronic properties of β-Sn islands deposited on a graphitized 6H-SiC (0001) substrate via low temperature scanning tunneling microscopy and spectroscopy. Owing to the confinement of the island geometry, quantum well states (QWSs) are formed, manifesting as equidistant peaks in the tunneling spectra. Furthermore, a distinct strip feature appears on the surfaces of odd-layer Sn islands, ranging from 15–19 layers, which is not present on the surfaces of even-layer Sn islands. The spatial distribution of strips can be modified by applying a bias pulse, using an STM tip. Furthermore, the strip-like structure shows significant impacts on the QWS. An energy splitting of the lowest unoccupied QWSs is observed in strip regions; this may be ascribed to caused the phase shift of the wave functions of the QWSs on the top surface, due to surface distortions created by the aforementioned strips.

The application of neuroimaging reconstruction technique in evaluating the relationship between skeletal musculature tumors and nerves nearby

Objective: To analyze the relationship between tumors of the musculoskeletal system and adjacent nerves by reconstructing images of peripheral nerves, and explore its value in surgical treatment. Methods: From May 2016 to April 2019, a total of 27 patients were collected in Department of Imaging,Shougang Hospital, who were with skeletal muscle system tumors, including 15 primary soft tissue tumors, 9 primary bone tumors, 3 metastatic tumors, all of them were closely related to nerves. There were 17 males and 10 females, aged 13-67 years, with an average age of 34 years. Before the operation, CT volume scanning was performed, and curved planar reconstruction (CPR) was used to reconstruct the peripheral nerves. All patients were operated within 2 weeks after the examination. According to the image characteristics before the operation, the nerve invasion was judged. The sensitivity, characteristic, positive predictive value and negative predictive value of the tumor invasion (compression) nerve were calculated according to the intraoperative findings as the gold standard. Result: Of the 27 cases, 25 cases (25/27, 92.6%) could show the relationship between the tumors and the adjacent nerves at the same level, and 22 cases (22/25, 88.0%) had the same preoperative image judgments as the intraoperative findings. In the reconstructed images, the peripheral nerve was a continuous strip-like structure on the same level with the tumor. The invaded nerve became thicker and the edge was blurred. Enhanced scan showed enhancement. The sensitivity, specificity, positive predictive value and negative predictive value of neuroimaging reconstruction were 100.0%, 89.5%, 75.0% and 100.0% respectively. The sensitivity, specificity, positive predictive value and negative predictive value of the nerve compression were 92.3%, 100.0%, 100.0% and 80.0% respectively. Conclusions: Neurological reconstructed images can help clinicians evaluate the relationship between lesions and adjacent nerves quickly and intuitively. They can guide the selection of surgical methods, reduce the risk of intraoperative nerve injury, and have high sensitivity and specificity for nerves invasion.

Effect of Cr content and cooling rate on the primary phase of Al-2.5Mn alloy

The effect of Cr content and cooling rate on the microstructure of Al-Mn alloy was studied using well resistance furnace melting, and the alloy was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The experimental results showed that adding Cr could significantly improve the morphology of the primary phase in the Al-2.5Mn alloy. Without Cr, the primary phase in the alloy was thick, needle-like, and strip-like structure. After adding 0.2wt%-0.5wt% Cr, the primary phase in the upper part of the alloy was gradually fined and reached the best effect at 0.35wt% Cr. When the content of Cr was 0.5wt%, the microstructure of the primary phase in the upper part began to coarsen. The bottom of the alloy was a large bulk phase, but still much finer than that without adding Cr. XRD and SEM analysis showed that the precipitation phase at the bottom was mainly Al85Mn7Cr8, while the fine microstructure at the top was Al6Mn and Al3Mn. The results of the cooling rate experiments showed that the primary phase of Al-2.5Mn-0.35Cr was further refined, and the eu-tectic microstructure was partly achieved, under air-cooling condition. And when the cooling method was iron die-cooling, the microstructure of the Al-2.5Mn-0.35Cr alloy was changed into a eutectic microstructure.

A Study on the Relationship Between Grain Size and Electrical Properties in (K,Na)NbO3‐Based Lead‐Free Piezoelectric Ceramics

AbstractThe 0.5 wt% MnO2‐doped 0.95(K0.5Na0.5)(Nb0.965Sb0.035)O3‐0.01CaZrO3‐0.04(Bi0.5K0.5)(Hf0.98Ti0.02)O3 (95KNNS‐1CZ‐4BKHT) lead‐free ceramics with grain size from 0.31 to 3.83 µm are fabricated by hot‐press sintering (HPS), microwave sintering (MS), conventional sintering (CS), two‐step sintering (TSS), and a combination of two of the above‐mentioned methods. Then, the grain size effects on the phase transition, electrical properties, domain structure, and temperature stability of the ceramics are investigated. The phase structure evolves from single rhombohedral (R) phase to coexisted rhombohedral‐tetragonal (R‐T) phases around 1 µm. The electromechanical properties are strongly grain size dependent. The values of piezoelectric coefficient (d33) and planar electromechanical coupling factor (kp) first rise sharply when the grain size is less than 1 µm, and then increase mildly in the grain size range from 2.55 to 3.04 µm and finally almost remain a constant (≈450 pC N−1 and 54%) when the grain size is larger than 3.31 µm. The R‐T phase coexistence and strip‐like nanodomain structure characterized by an easier switching feature contribute to the high piezoelectric and electromechanical properties of coarse‐grained samples. This work not only clarifies the relationship between grain size and electrical properties in KNN‐based ceramics, but also provides a novel strategy for developing high‐performance lead‐free piezoceramics.

Traces for homogeneous Sobolev spaces in infinite strip-like domains

In this paper we construct a trace operator for homogeneous Sobolev spaces defined on infinite strip-like domains. We identify an intrinsic seminorm on the resulting trace space that makes the trace operator bounded and allows us to construct a bounded right inverse. The intrinsic seminorm involves two features not encountered in the trace theory of bounded Lipschitz domains or half-spaces. First, due to the strip-like structure of the domain, the boundary splits into two infinite disconnected components. The traces onto each component are not completely independent, and the intrinsic seminorm contains a term that measures the difference between the two traces. Second, as in the usual trace theory, there is a term in the seminorm measuring the fractional Sobolev regularity of the trace functions with a difference quotient integral. However, the finite width of the strip-like domain gives rise to a screening effect that bounds the range of the difference quotient perturbation. The screened homogeneous fractional Sobolev spaces defined by this screened seminorm on arbitrary open sets are of independent interest, and we study their basic properties. We conclude the paper with applications of the trace theory to partial differential equations.

Investigation of cyclic voltammetry, impedance spectroscopy and electrical properties of thermally exfoliated biomass-synthesized graphene

In this paper we have reported the synthesis of graphene by a novel and facile thermal exfoliation process of Allium cepa (Onion) and was characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy to investigate the morphological and structural properties and chemical networks present on it. The AFM and SEM images revealed the formation of thin strip-like layered structure of graphene with the thickness of 1.1 nm. The electrochemical properties of graphene were characterized by cyclic voltammeter, impedance spectroscopy, Tafel plot, Nyquist plot, Bode plot, and voltage-dependent impedance using 0.5 M H2SO4 electrolyte as an illustrative standard material. The cyclic voltammetric curve of graphene electrodes determined a quasi-reversible electrochemical behavior under linear diffusion control square shape at higher process temperature. The ratio of atomic % C-to-O varied from 7.57 to 24.04 indicating a decrease in the oxygen content for the graphene processed at higher temperature. The areal capacitance and voltage-dependent impedance varied from 8.59 × 10− 5 to 18.8 × 10− 5 F/cm2 and 15.79 to 7.7 Ohm, respectively, with the process temperature varying from 600 to 1000 °C. The corrosion potential (Ecorr) and corrosion current density (Icorr) values are − 0.12 V and − 9.1A/cm2, respectively, for the graphene processed at 1000 °C.

Influence of annealing temperature on microstructure and tensile property of cold-rolled Fe-0.2C-11Mn-6Al steel

To fully realize the potential of austenite characterized by strip-like and equiaxed structure and enhance the comprehensive mechanical properties of medium-Mn steel, the as-hot-rolled Fe-0.2C-11Mn-6Al steel was subjected to cold roll annealing to refine the grain size. The ultimate tensile strength of the cold-rolled steel annealed at 650 °C was significantly enhanced, while the total elongation was markedly decreased. The variation in tensile properties of the annealed cold-rolled steel was due to weakening of transformation induced plasticity (TRIP) effect and enhanced twinning induced plasticity (TWIP) effect with increase in quenching temperature. Furthermore, austenite had two different morphologies, strip-like and granular. Though the grain size of granular austenite increased with increased annealing temperature, the austenite stability increased with increase in quenching temperature, which is contrary to the expectations. This is attributed to refinement of large austenite strips induced by recrystallization.

Facile transformation of low cost melamine–oxalic acid into porous graphitic carbon nitride nanosheets with high visible-light photocatalytic performance

The high visible-light photocatalytic performance of porous g-C3N4nanosheets were prepared by using a long strip-like structure of melamine–oxalic acid (MO) as a precursor.

Molybdenum Carbide Anchored on Graphene Nanoribbons as Highly Efficient All-pH Hydrogen Evolution Reaction Electrocatalyst

The demand for exploiting hydrogen as a new energy source has driven the development of feasible, efficient, and low-cost electrocatalysts for hydrogen evolution reaction (HER) in different reaction media. Herein, we report the synthesis of molybdenum carbide (Mo2C) nanoparticles anchored on graphene nanoribbons (GNRs) as HER electrocatalyst that can function well under acidic, basic, and neutral conditions. GNRs obtained by unzipping carbon nanotubes (CNTs) display strip-like structure, offering abundant active sites for growing Mo2C nanoparticles. Furthermore, GNRs could provide a fast electron transport pathway as well as large exposed surface area to allow full impregnation of electrolytes. Coupling with the anticorrosion feature of Mo2C nanoparticles, the Mo2C–GNR hybrid exhibits outstanding electrocatalytic performance in all of the acidic, basic, and neutral media, making it promising as a highly efficient electrocatalyst under conditions at all pH values.

The MYB36 transcription factor orchestrates Casparian strip formation

The endodermis in roots acts as a selectivity filter for nutrient and water transport essential for growth and development. This selectivity is enabled by the formation of lignin-based Casparian strips. Casparian strip formation is initiated by the localization of the Casparian strip domain proteins (CASPs) in the plasma membrane, at the site where the Casparian strip will form. Localized CASPs recruit Peroxidase 64 (PER64), a Respiratory Burst Oxidase Homolog F, and Enhanced Suberin 1 (ESB1), a dirigent-like protein, to assemble the lignin polymerization machinery. However, the factors that control both expression of the genes encoding this biosynthetic machinery and its localization to the Casparian strip formation site remain unknown. Here, we identify the transcription factor, MYB36, essential for Casparian strip formation. MYB36 directly and positively regulates the expression of the Casparian strip genes CASP1, PER64, and ESB1. Casparian strips are absent in plants lacking a functional MYB36 and are replaced by ectopic lignin-like material in the corners of endodermal cells. The barrier function of Casparian strips in these plants is also disrupted. Significantly, ectopic expression of MYB36 in the cortex is sufficient to reprogram these cells to start expressing CASP1-GFP, correctly localize the CASP1-GFP protein to form a Casparian strip domain, and deposit a Casparian strip-like structure in the cell wall at this location. These results demonstrate that MYB36 is controlling expression of the machinery required to locally polymerize lignin in a fine band in the cell wall for the formation of the Casparian strip.

Synthesis, structure and properties of a tetranuclear europium(III) complex based on 9,9-dimethylfluorene-2,7-diphosphonic acid

One tetranuclear europium(III) phosphonate complex [Eu2(H4MFDP)(H3MFDP)4(H2MFDP)(H2O)4]·13.5H2O (EuMFDP), has been prepared by reactions of the new ligand 9,9-dimethylfluorene-2,7-diphosphonic acid (H4MFDP) with europium(III) nitrates. The crystal structure of complex EuMFDP has been determined using single-crystal X-ray diffraction. It features a strip-like tetranuclear structure, in which four ligands and four Eu(III) ions constitute the core. Interestingly, the four ligands in the core possess paddle-like arrangement. Although the free ligand H4MFDP exhibits the emission centered at 333nm and 438nm upon excitation at 310nm, complex EuMFDP shows only very weak characteristic emission of Eu(III) ions, probably due to the strong quenching effect of OH vibration. The thermal property of EuMFDP has also been studied.