Black Sheet Research Articles

Mulches Improve Ridge‐tillage Tomato Production under Drip Irrigation with Saline Water

Core Ideas Soil salinity three years after first growing season was fluctuated slightly.Soil salinity under wheat straw was lower than both waterproof and pervious plastic mulch.Wheat straw improved tomato yield, followed by black waterproof plastic mulch. Fresh water resources in the North China Plain are declining due to increasing industrial and domestic water use. These uses raise the agricultural demand for low quality water. To provide appropriate management techniques for safely using saline water, different mulching materials were tested on ridge‐tillage tomato (Lycopersicon esculentum Mill.). Four treatments: control (bare land, CK), black plastic (BPM), black sheet net (BSN), and wheat straw (SM) were designed to: (i) evaluate the effects of mulching on the irrigation amount, soil salinity, tomato yield, and irrigation water productivity (IWP); and (ii) develop integrated irrigation strategies using saline water securely. The average required water for the SM and BPM treatments reduced by 12 and 20%, respectively. Electrical conductivity of saturated paste extracts (ECe) increased from 1.91 to 4.07 dS m−1 in 0‐ to 40‐cm root zone and from 2.33 to 4.24 dS m−1 in 0‐ to 120‐cm soil profile after the first year irrigation, and then fluctuated slightly during the next 3 yr due to precipitation and evaporation. The ECe for the SM treatment was always the least in 4 yr. Compared with CK, the BPM and SM treatments over 4 yr increased the average tomato yield by 26 and 42%, and increased the average IWP by 62 and 70%, respectively. Therefore, straw mulching was the best mulching material to safely use saline water of <6.3 dS m−1 for the ridge‐tillage tomato under drip irrigation, followed by black plastic mulching, in a temperate semi humid monsoon climate zone.

Self-assembly carbon dots for powerful solar water evaporation

Solar-driven water vaporization is considered one of the most sustainable technologies to solve water scarcity. However, the advanced design solar absorber system is still required for highly efficient steam generation. Here we develop a novel system for water evaporation through assembly of carbon dots within microchannels of processed wood. Not only is a dual-layer structure including of heat barrier and water transport channel formed, but also the modulation of carbon dot energy structures in favor of photothermal conversion is realized synchronously. This system exhibits higher water evaporation rate and energy efficiency for solar to steam generation than other black photothermal sheets (e.g. carbon nanotube, graphene, graphene oxide). On the one hand, the constructed size-dependent vaporization enthalpy theory shows that the micropores are beneficial to reduce vaporization enthalpy of water. On the other hand, the presented direct evidences for the roles of oxidation functional groups in solar thermal evaporation demonstrate that hydroxyl groups can improve solar-to-heat efficiency. Therefore, tailoring pore sizes and surface functional groups could be an efficient method for solar-to-vapor systems.

Effect of shade level and mulch type on growth, yield and essential oil composition of damask rose (Rosa damascena Mill.) under mid hill conditions of Western Himalayas.

A field experiment was conducted at the experimental farm of CSIR-Institute of Himalayan Bioresource Technology, Palampur, India for two consecutive years (2015–16 and 2016–17). The aim of the study was to test the hypothesis whether different shade level and mulch type would influence the growth, flower yield and essential oil profile of R. damascena. Yield attributes viz., numbers of flowers plant-1, fresh flower weight plant-1, flower yield, and essential oil yield were significantly higher under open sunny conditions as compared to 25% and 50% shade levels. However, plants grown under 50% shade level recorded significantly higher plant height (cm), plant spread (cm) and the lowest numbers of branches as compared to control. Among mulches, black polyethylene mulch recorded significantly higher growth, and yield attributes of damask rose as compared to other mulches. Black polyethylene mulch recorded 74.5 and 39.2% higher fresh flower yield as compared to without mulch, during 2015–16 and 2016–17, respectively. Correlation studies showed a positively significant correlation between quality and quantity traits. A total of twenty-six essential oil compounds were identified which accounted for a total of 88.8 to 95.3%. Plants grown under open sunny conditions along with the applications of black polyethylene mulch produced a higher concentration of citronellol and trans-geraniol. Damask rose planted in open sunny conditions and mulched with black polyethylene sheet recorded significantly higher flower yield.

Gate voltage and doping effects on near-field radiation heat transfer in plasmonic heterogeneous pairs of graphene and black phosphorene.

Plasmon coupling and hybridization in 2D materials plays a significant role for controlling light–matter interaction at the nanoscale. We present a near-field radiation heat transfer (NFRHT) between vertically separated graphene and black phosphorene sheets at different temperatures in nanoscale separations. Radiation exchange from the theory of fluctuation electrodynamics is modulated by the carrier density of graphene and phosphorene. Direct comparison of NFRHT black phosphorene–graphene to symmetric graphene–graphene radiation exchange can be as much as 4 times higher for the selected doping range in both armchair (AC) and zigzag (ZZ) orientations of BP. The strong NFRHT enhancement of the specific optical properties of the heterogenous 2D material is due to the strong coupling of propagating surface plasmon polaritons as demonstrated by the distribution of the heat transfer coefficient. We also demonstrate that the magnitude of the near-field radiation enhancement is found to acutely depend on the vacuum gap of the graphene and BP pair. Interestingly, for separation distances below 200 nm, the total near-field heat transfer between black phosphorene and graphene exceeds that between graphene and graphene by 5 times. The radiation enhancement can be further tuned based on the orientation, AC, and ZZ of black phosphorene. These results prominently enable dynamic control of the total NFRHT relying on tunable anisotropic characteristics of BP irrespective of graphene's optical conductivity. Furthermore, the heterogeneous pairs of 2D materials potentially provide alternative platforms to achieve beyond super-Planckian radiation.

Mulches enhanced growth and yield of onion

The experiment was conducted to investigate the effect of mulches on soil nutrients and microclimate status, growth and bulb yield of onion cv. Taherpuri. The experiment was comprised of six mulches viz., i) Control (no mulch), ii) Black polythene sheet, iii) White polythene sheet, iv) Rice straw, v) Water hyacinth and vi) Saw dust. Application of different mulches improved soil microclimates, increased plant growth and bulb yield over control. Among the mulches, black polythene mulch showed superiority in growth and yield contributing characters compared to other mulches, resulting the highest bulb yield.Bangladesh J. Sci. Ind. Res.53(4), 305-310, 2018

Thermal Properties of Palm Fronds (Krino) for Utilizing as a Thermal Insulation Material

Insulation materials are of great importance for conserving stored energy and maintaining temperatures in cooling or heating processes. The cost of insulation materials is a large part of the initial, maintenance and repair costs. Glass-wool insulation namely exchanges in a short time due to its absorption of moisture resulting in decreasing the insulation value. Disposal of glass-wool insulation material constitutes an environmental problem due to its difficultly of degradation. The palm leaves are considered as a great field residues annually produce in Egypt and the Arab countries when each palm produces more than 25 kg per year and the number of palm trees in Egypt is more than 17 million palms. These field residues are rich in cellulose, sugars and many other important elements that can be used in different industries or extraction of important natural materials, which provide return an economic benefits instead of burning them. To achieve the goal of this research, four cylindrical metallic tanks made of black iron sheet, each one having gross dimensions of 50 cm long, 30 cm in dimeter, and 1 mm thick. Three tanks were thermal insulated using krino as an insulation material, with three different densities of insulation (50, 60, and 70 kg/m3) and 5 cm thick. The fourth tank was insulated using 5 cm thick of glass wool. The most important results of the thermal conductivity test of krino revealed that the thermal conductivity of the krino depends on its density and temperature. The best density was 50 kg/m3. The values of thermal conductivity of the three different densities was ranged between 0.0954 and 0.190 W/m K)

Nonlinear vibrations of circular single-layer black phosphorus resonators

A strong nonlinear relationship between the displacement and the load in single-layer black phosphorus sheets (SLBPs) was observed under the large deflection by nanoindentation experiments. However, the nonlinear effect is rarely considered in the Nano-Electro-Mechanical-System (NEMS) resonators based on the SLBPs. In this letter, nonlinear static and dynamics behaviors of circular SLBPs (CSLBPs) are investigated using molecular dynamics (MD) simulations and a nonlinear orthotropic plate model (NOPM), respectively, where the geometrical nonlinearity is systematically considered in the NOPM. Our results show that the response-frequency curves of forced vibrations in CSLBPs meet clear hardening-type nonlinearity. The damping ratios of CSLBPs are proportional to the square of the vibration amplitude. In particular, the NOPM together with the law of energy equipartition is further utilized to study the nonlinear thermal vibrations of the CSLBPs. Checking against present MD calculations shows that the solution of the present NOPM has high accuracy. The present study should be of great help for designing NEMS resonators based on two-dimensional (2D) orthotropic materials.

Near-field radiative heat transfer between black phosphorus and graphene sheet

Low thermal conductivity of black phosphorus (BP) makes it difficult to cool BP-based electronic or optoelectronic devices. Therefore, developing a cooling strategy for BP-based nano devices is highly required. We theoretically study the near-field radiative heat transfer between BP sheets as well as between BP and graphene. We find that the heat transfer between BP sheets is determined by its electron doping. Plasmons excited by BP in different directions dominate the heat transfer for different electron doping. At optimum electron doping, heat transfer between the BP sheets increases significantly. The heat transfer between BP and graphene is dependent on both the electron doping of BP and chemical potential of graphene. Modulating the chemical potential of graphene can result in a strong coupling between graphene plasmons and BP plasmons, which will lead to a significant enhancement of heat transfer between BP and graphene. Our results are not only meaningful in controlling the heat transfer between BP-based structures but also helpful in developing cooling strategies for BP-based nano devices.

Przemiany społeczno-kulturowe w okresie formowania się państwa piastowskiego w Wielkopolsce północno-zachodniej na podstawie materiałów archeologicznych z Santoka i Międzyrzecza

The middle and upper Obra river basin is an environmentally unique area. This large area, located in the vicinity of black soil sheets, is characterized by very favorable conditions for human occupation. The first Neolithic settlements are related to the Linear Band Pottery culture. The most commonly represented Neolithic societies belong to the Funnel Beaker Culture. During the Late Neolithic, the area was less intensively occupied. This process may be related to climate changes. The Early Bronze Age was represented in the middle Obra river basin by the Kościan group of the Unetice culture – a local community with the barrow cemetery in Łęki Małe and the fortified settlement in Bruszczewo. A continuous occupation of this area from the Early Neolithic Age to the Early Bronze Age has been proved.

Spray‐On Reduced Graphene Oxide‐Poly(vinyl alcohol) Supercapacitors for Flexible Energy and Power

AbstractFlexible and mechanically robust energy storage devices, such as capacitors, are future enablers of the next generation of structural energy and power, flexible electronics, and biometrics. These concepts require that the capacitor be seamlessly integrated into the device in a scalable process, while still maintaining mechanical and electrochemical properties. The challenge is that ease‐of‐processing, mechanical, and electrochemical properties are not mutually exclusive. Spraying allows for fast manufacture, but producing an ink amenable to spraying is challenging because of aggregation of the electroactive materials in the dispersion, resulting in poor performance. Here, sprayable, flexible supercapacitor electrodes are demonstrated containing reduced graphene oxide (rGO), poly(vinyl alcohol) (PVA), and carbon black achieved via high‐throughput air‐brushing process from aqueous media. The spray processing, mechanical properties, and electrochemical performance of various compositions of rGO, PVA, and carbon black are explored. rGO sheets provide capacitive energy storage, PVA facilitates air‐brushing, and carbon black bridges rGO sheets to form electronic pathways. Due to the good combination of mechanical and electrochemical properties, a flexible supercapacitor shows steady capacitance retention after several bending cycles. This spray‐on three‐component composite electrode balances electrochemical and mechanical properties, which is otherwise difficult to realize for compact brick and mortar structures, especially from airbrushing.

Evaporation induced electricity generation in freestanding and flexible carbon-based hybrid film

Energy harvesting from ambient environment attracts widespread interest for its great potential in green and sustainable development. Very recently, evaporation, a ubiquitous process existing in nature was demonstrated as a reliable process, which can convert low-grade thermal energy in environment into electricity. Evaporation-driven water flow within a piece of carbon black sheet or printed porous carbon film could generate sustainable direct-current electricity with open-circuit voltage ( V oc) up to 1 V, and with lifetime over hundreds of hours. However, both the flame-deposited carbon black sheets and all-printed porous carbon films need to be deposited or printed on rigid substrates (e.g., silica glass and Al2O3 plate) in the previous work, which has deceased the effective evaporation area and occupied excessive space, thus limiting the application of this new energy harvesting strategy as a practical power source. In this work, we present the fabrication of a flexible and freestanding carbon nanoparticles/glass fiber hybrid film (CNGF) for electricity generation via evaporation-driven water flow within it. The CNGF hybrid film has a structure of reinforced concrete, thus exhibits good flexibility and mechanical properties. The carbon film with the size of 1 cm × 4.5 cm × 0.13 mm and glassfiber/carbon nanoparticle mass ratio of 0.6, has a max tensile stress of 4.9 MPa. The electrical resistance of the carbon film keeps nearly unchanged after 10000 bends at a max bending angle of 90°, indicating its excellent flexibility. Without the limit of rigid substrates, the double-side evaporation enables higher water flow rate through the film. The freestanding carbon film thus has higher electrical power output than the carbon films reported before. A device with the size of 1 cm × 4.5 cm × 0.13 mm generates an open-circuit voltage of ~1 V and current of ~ 0.86 μA under ambient condition. The hybrid carbon film can also be easily scaled-up. We demonstrated a carbon film with the maximum width of 40 cm, which has an output current of ~28 μA. Furthermore, the excellent flexibility allows the film to be rolled up to save space, even with a high power output. To demonstrate the application of carbon film, we successfully degraded methylene blue (MB) by using our device as power source. Given the simple fabrication, robust mechanical property, high electricity output, such a freestanding and flexible carbon-based hybrid film shows great potential in environmental energies harvesting for green and sustainable development.

Near-Field Radiative Heat Transfer between Black Phosphorus Sheets via Anisotropic Surface Plasmon Polaritons

Black phosphorus (BP), a novel natural two-dimensional layered material with intrinsic in-plane anisotropy, has been attracting significant research attention due to its outstanding electronic and optical properties and tunable bandgaps. Here, an enhancement of near-field radiative heat transfer (NFRHT) arising from a coupling of anisotropic surface plasmon polaritons (SPPs) between two layered BP sheets is demonstrated. The coupling of SPPs along armchair and zigzag directions dominate the NFRHT at near-infrared and mid-infrared frequencies, respectively. The dependence of NFRHT on the number of layers as well as the electron density of BP is then analyzed. It is found that at a small gap size the NFRHT between BP sheets with more number of layers and a higher electron density is lower. While this trend is reversed at a large gap size. Finally, the possibility of using BP to modulate the NFRHT by the mechanical rotation is explored. It is shown that the rotated system exhibits a nonmonotonic dependency o...

Active Tuning of Midinfrared Surface Plasmon Resonance and Its Hybridization in Black Phosphorus Sheet Array

The behaviors of anisotropic plasmons in black phosphorus have been fully exploited across a complete variety of system including individual nanoribbon, vertically offset paired ones, and nanoribbon/sheet hybrid system. Benefiting from its two-dimensional nature, plasmons can be actively controlled by either geometrical parameters or the carrier doping in black phosphorus, which allows for the emerging phenomenon of strong light–matter interaction at mid-infrared region. Remarkably, Rabi splitting over 17.3 meV is observed in the plasmonic spectra of the nanoribbon/sheet hybrid structure as harnessed by the strong interaction of coupled plasmons. We also propose a scheme that supports plasmon on a continuous monolayer black phosphorus by using a diffraction grating. By adjusting the geometrical parameters of the grating and the Fermi level of the black phosphorus slightly, the resonance wavelength can be changed notably. The results appealing open up possibilities of devising black phosphorus-based plasmo...

Ultra-thin TiO2 sheets with rich surface disorders for enhanced photocatalytic performance under simulated sunlight

Ultra-thin hydrogenated black TiO2 sheets with rich surface disorders were prepared by a facile hydrogenation of submicrometer sized TiO2 sheets. Due to the reduced band gap of 2.81 eV, the light harvesting ability of black TiO2 sheets is enhanced in the visible range. In addition, the rich surface disorder reduces the primary particle-size and increases the surface area from 20.9 to 46.2 m2g-1, which enhances the population of active catalytic sites and substantially improves the photocatalytic activities both under visible light and full spectrum solar light. The mechanism tests indicate the black TiO2 sheets triggered photodegradation is a hole mediated process. Moreover, the catalyst shows long-term stability, which permits its potential application in the real waste water treatment.

Passively Q-Switched Yb-Doped All-Fiber Laser With a Black Phosphorus Saturable Absorber

We report two kinds of Q-switched Yb-doped fiber lasers based on a black phosphorus saturable absorber (BP-SA). The BP-SAs are prepared by two different methods, one of which is the mechanical exfoliation method and the other is the liquid-phase exfoliation method. The BP-SAs are inserted into the all-fiber Yb-doped oscillation cavity in different forms. We have experimentally shown that the passively Q-switched pulse trains could be obtained by the two methods. First, we achieve the Q-switched pulse in 1029.63 nm by using a few-layer black phosphorus sheet. The fiber laser was capable of generating pulses with a maximum average output power of 13.12 mW and a repetition rate of 79.46 kHz, corresponding to the maximum single-pulse energy of 165.11 nJ and the shortest single-pulse width of 1.55 μs. In addition, we obtain narrower pulsewidth by dropping the black phosphorus solution onto the tapered fiber. The maximum single pulse energy of 114.72 nJ and the minimum pulsewidth of 1.09 μs were obtained. The repetition rate ranges from 49.13 to 101.3 kHz.

Assessment of the possibility of unglazed transpired type solar collector to be used for drying purposes: a comparative assessment of efficiency of unglazed transpired type solar collector with glazed type solar collector

Energy, which has become a key issue in global scale, has already posed a threat for the existence and development of mankind. Due to environmental degradation associated with energy consumption in all sectors, it is required to focus on utilization of sustainable energy sources. Solar energy, which is an environment friendly and sustainable energy source, is a promising alternative for fossil fuels. Drying processes in industrial sector accounts for about 12 to 20% of the total energy consumption. In developing countries, solar drying is utilized as a decentralized thermal application for the food preservation. Though natural sun-drying does not involve any cost, there are many disadvantages such as long drying time, contamination and intrusion of insects and rodents, which will result in low quality dried material. Currently, unglazed transpired type solar collectors are commonly used for building heating purposes but rarely for agricultural purposes. To check the possibility of unglazed transpired type solar collectors to be used for drying purposes, this study was conducted to compare the efficiency and performance of unglazed transpired type solar collector with conventional glazed type solar collector in local conditions. Dimensions of both solar collectors were designed as 1m x 1m in size. 5mm thick transparent glass sheet and perforated black painted metal sheet were used for solar radiation transmission in glazed type solar collector and unglazed transpired type solar collector respectively. Inlet and outlet temperature of both types of solar collectors, solar radiation, ambient temperature, wind speed and surrounding relative humidity were monitored. When compare the two types of solar collectors, there were no significant difference of solar collector’s temperature at their outlets with various levels of ambient temperature (28-32 °C), solar radiation (95.21-504.28 W/m2) and wind speed (0.43-1.05 m/s). The efficiency of unglazed transpired type solar collector was observed as 38.41 % under 0.0077 m3/s airflow rate, with average solar radiation of 304.24 W/m2. During lower solar radiation levels, comparatively higher collector’s efficiency was observed in unglazed transpired type solar collector than in glazed type solar collector. In addition, unglazed transpired type solar collector is a low cost and robust heating system. Hence, there is a potential to utilize unglazed transpired type solar collector as a substitute for glazed type solar collector for agricultural drying processes.

Design of Radar Absorbing Structures Utilizing Carbon-Based Polymer Composites

Radar absorbing structure (RAS) is a composite laminate with a low reflection coefficient for the electromagnetic illumination in microwave frequency range, and thereby can be used in the stealth technology and electromagnetic compatibility (EMC). In this study, microwave absorbing properties of a two-layer composite laminate (carbon black impregnated rubber sheet attached to the carbon fiber–epoxy composite panel) has been investigated. Complex permittivity and permeability of the composite materials were measured in C- and X-band frequencies (4–12 GHz) by reflection/transmission technique using a coaxial waveguide and network analyzer. Complex permittivity can be controlled with the amount of carbon black in the rubber composite. High values of dielectric constant and dielectric loss are observed in the carbon fiber composite. Optimization of microwave absorption is conducted for the two-layer RAS on the basis of transmission line theory. It is found that microwave absorption is strongly sensitive to carbon black content in the rubber composite and its layer thickness. For the rubber sheet containing 10% carbon black (with dielectric constant ≍5), the maximum microwave absorption (30 dB) is predicted at 10 GHz.

Design and evaluation of scaring devices for the management of avian pests of oil palm (Elaeis guineensis Jacq.)

Birds cause extensive damage to ripening oil palm fruits. Various methods and devices were evaluated for managing this menace in the past. The scaring devices designed in the present study using Compact Disks (CDs) proved effective in reducing the damage caused by avian pests on the ripening fruit bunches of oil palm. To increase the deterrent effect of CDs, the non-reflective sides were stuck with either red or yellow or black reflective radium sheets. Onto which two circular, concentric eye spots were designed and stuck horizontally. The CDs having circular eye spots stuck on red and yellow radium sheets protected the ripening fruit bunches from further damage by birds until harvest. The statistical analysis showed that the above treatments protected the ripening bunches from bird damage by 100 per cent. Protection was 97.2 per cent in the case of CDs having circular eye spots stuck on black radium sheets. CDs having no eye spots and radium sheet protected the bunches 84.6 per cent compared to control. This finding indicated that these devices could be effectively used judiciously to protect the ripening fruit bunches until harvest from avian pests in oil palm.

Effects of the Formulations of Silicon-Based Composite Anodes on their Mechanical, Storage, and Electrochemical Properties.

In this work, the effects of the formulation of silicon-based composite anodes on their mechanical, storage, and electrochemical properties were investigated. The electrode formulation was changed through the use of hydrogenated or modified (through the covalent attachment of a binding additive such as polyacrylic acid) silicon and acetylene black or graphene sheets as conducting additives. A composite anode with a covalently grafted binder had the highest elongation without breakages and strong adhesion to the current collector. These mechanical properties depend significantly on the conductive carbon additive used and the use of graphene sheets instead of acetylene black can improve elongation and adhesion significantly. After 180 days of storage under ambient conditions, the electronic conductivity and discharge capacity of the modified silicon electrode showed much smaller decreases in these properties than those of the hydrogenated silicon composite electrode, indicating that the modification can result in passivation and a constant composition of the active material. Moreover, the composite Si anode has a high packing density. Consequently, thin-film electrodes with very high material loadings can be prepared without decreased electrochemical performance.

Effects of various defects on the mechanical properties of black phosphorene

The present work investigates the effects of seven types of defects on the mechanical properties of black phosphorene. Molecular dynamics finite element method with Stillinger-Weber potential is used to simulate the uniaxial tensile tests of the pristine and defective black phosphorene sheets. Young's modulus, fracture stress, and fracture strain of the pristine and defective black phosphorene sheets are estimated. Comparison of the influence of different types of defects on the mechanical response of black phosphorene is considered. Fracture mechanism of various defective black phosphorene sheets is also analyzed. It is found that effect of the defects on Young's modulus of black phosphorene is insignificant. In contrast, due to defects fracture stress and fracture strain can reduce up to 53% and 69%, respectively. Results provide a landscape on the mechanical properties of defective black phosphorene and are useful for the design of nanodevices with black phosphorene in future applications.