Wet Bulk Research Articles

A Pilot Plant Study on the Autoclaving of Food Wastes for Resource Recovery and Reutilization

Autoclaving of food wastes (FW) for the resource recovery and reutilization was studied using the pilot plant scale. Experiments were conducted at various temperatures of 408, 428, and 438 K and times of 15 and 60 min. The in-filled steam to the autoclave was supplied by the incineration plant with a gauge pressure of 7 kg/cm2 and a temperature of 443 K or above. The results obtained from the experiments show that the less energy- and time-consuming autoclaving conditions (408 K and 15 min, denoted as Case A408-15) are effective. Comparisons of the properties and characteristics of autoclaved FW (FWA) of Case A408-15 with those of FW are made. The wet bulk volume and wet bulk density of FW A are dramatically reduced to 15.64% and increased to 313.37% relative to those of FW, respectively. This makes the subsequent processing and reuse for FWA more convenient than FW. The autoclaving results in an increase of carbon content and a decrease of nitrogen content, and thus an increase of the C/N ratio of FWA. The contents of sulfur, hemi-cellulose, and cellulose of FWA are also reduced. All these fluctuations are beneficial for making compost or other usages from FWA than FW. The autoclaved liquid product (LA) separated from FWA and liquid condensate (LC) from the released gas possess high COD and TOC. These two liquids can be mixed for use as liquid fertilizers with proper conditioning. Alternatively, further anaerobic digestion of the mixture of FWA, LA, and LC can offer enhanced biogas production for power generation. All these thus match the appeal of sustainable materials management and circular economy. The emitted gas from autoclaving contains no CO and some hydrocarbons. Suitable air pollution control is needed. The results and information obtained are useful for the proper recovery and reuse of abundant food wastes from domestic households and food industries.

Heavy metals transport pathways: The importance of atmospheric pollution contributing to stormwater pollution

Pollution has become a serious issue in the urban water environment as stormwater runoff transports a range of pollutants to receiving water bodies, undermining water quality and posing human and ecosystem health risks. Commonly, the primary focus of stormwater quality research is on the role of pollutants directly accumulating at the ground phase. However, atmospheric phase can also exert a significant impact on stormwater quality through atmospheric deposition. Unfortunately, only limited research has focused on the linkage between atmospheric and ground phases in relation to urban stormwater quality. The study discussed in this paper characterised the four primary transport pathways, atmospheric build-up (AB), atmospheric deposition (AD) and road surface build-up (BU) and wash-off (WO) in relation to heavy metals, which is a key urban stormwater pollutant. The research outcomes confirmed the direct linkage between atmospheric phase and ground phase and in turn the significance of atmospheric heavy metals as a contributing source to stormwater runoff pollution. Zn was the most dominant heavy metal in all four pathways. For the AB pathway, atmospheric heavy metal pollution on weekdays is more serious than weekends. For the AD pathway, dry atmospheric deposition of heavy metals is positively correlated to dry days, whilst wet (bulk) deposition is related to rainfall depth. For the BU pathway, heavy-duty vehicle traffic volume was found to be the most important source. For the WO pathway, industrial and commercial areas tend to produce higher heavy metal concentrations in stormwater runoff than residential areas. The study results will contribute to the creation of effective urban stormwater pollution mitigation strategies and thereby enhancing the quality of the urban water environment.

Assessment of Shippers and Ship Owners Ship and Charter Type Choice in the Wet and Dry Bulk Ship Brokering Market: Knowledge Guide for African Indigenous Ship Brokers

Abstract The study assessed shippers and ship owners’ ship and charter party type choices in the wet and dry bulk ship broking and chartering market as guide for performance improvement for African and Nigerian ship brokers. It aims to determine if significant differences exists between shippers ship type choices among Very Large Crude Carriers (VLCC), Handymax, Supramax and capsize vessels in the wet and dry bulk market as well shippers and ship owners charter party type choice between voyage charter and time charter for the various ship types. The study adopted a survey method in which the Baltic International Maritime Council (BIMCO) was surveyed and 5 year data on ship types and charter party type choices of shippers and ship owners was obtained. The statistical tools of Analysis of Variance (ANOVA) and independent sample t-test were used to compare the ship type choices and charter party type choices of shippers and ship owners. The result indicates that shippers’ in the wet and dry bulk cargo market show greater preference for Supramax vessel type. The aggregate number of vessels chartered over the period covered in the study is 41,684 vessels out of which 22,593 representing about 54.2% are Supramax. This was seconded by VLCC which recorded 8,829 or 21.2% charters. Capsize and Handymax vessel types had 6211 and 4069 charters respectively which represent 14.9% and 9.77% each. Shippers and ship owners also show greater preference for voyage charter party type than time charter party for all types of vessels. It was recommended that ship brokers should place greater priority on trading in Supramax ship types and voyage charter party type as the demand trend for this ship type is likely to remain higher over time; followed by VLCC; while more shippers and ship owners are likely continue to show preference for voyage charter than time charter.

An analysis of stepped trapezoidal-shaped microcantilever beams for MEMS-based devices

Microcantilever beams are the most widely used mechanical elements in the design and fabrication of MEMS/NEMS-based sensors and actuators. In this work, we have proposed a new microcantilever beam design based on a stepped trapezoidal-shaped microcantilever. Single-, double-, triple- and quadruple-stepped trapezoidal-shaped microcantilever beams along with conventional rectangular-shaped microcantilever beams were analysed experimentally, numerically and analytically. The microcantilever beams were fabricated from silicon dioxide material using wet bulk micromachining in 25 wt% TMAH. The length, width and thickness of the microcantilever beams were fixed at 200, 40 and 0.96 µm, respectively. A laser vibrometer was utilized to measure the resonance frequency and Q-factor of the microcantilever beams in vacuum as well as in ambient conditions. Furthermore, finite element analysis software, ANSYS, was employed to numerically analyse the resonance frequency, maximum deflection and torsional end rotation of all the microcantilever beam designs. The analytical and numerical resonance frequencies are found to be in good agreement with the experimental resonance frequencies. In the stepped trapezoidal-shaped microcantilever beams with an increasing number of steps, the Q-factor, maximum deflection and torsional end rotation were improved, whereas the resonance frequency was slightly reduced. Nevertheless, the resonance frequency is higher than the basic rectangular-shaped microcantilever beam. The observed quality factor, maximum deflection and torsional end rotation for a quadruple-stepped trapezoidal-shaped microcantilever are 38%, 41% and 52%, respectively, which are higher than those of conventional rectangular-shaped microcantilever beams. Furthermore, for an applied concentrated mass of 1 picogram on the cantilever surface, a greater shift in frequency is obtained for all the stepped trapezoidal-shaped microcantilever beam designs compared to the conventional rectangular microcantilever beam.

The impact of ice class on the economics of wet and dry bulk shipping in the Arctic waters

ABSTRACTShipping in Arctic waters is subject to technical requirements posed by harsh ambient conditions. Vessels operating in ice-infested waters need reinforced hulls and more powerful engines, for example. These requirements are reflected in the vessel’s ice class, which has specific implications not only for operational issues but also for shipping economics. This article examines the extent to which the shipping costs of wet and dry bulk vessels compliant with the International Association of Classification Societies (IACS) Polar Class rules exceed those of vessels without an ice class.Descriptive statistics and multiple regression analysis were used to estimate differentials in capital and fuel costs, as well as in cargo-carrying capacity. The applied dataset, obtained from two major shipping registries, includes technical details of 21,352 bulk vessels, of which 711 possessed a PC, and the remaining 20,641 comprised the reference category.The results show that Polar Class compliant vessels could be up to three times more expensive to build than vessels without an ice class. Moreover, the respective increase in fuel costs may account for up to 150 per cent given the additional engine power and the increased hull weight. Finally, the reduction in cargo-carrying capacity amounts to 20 per cent compared to the reference category.

Acoustic impedance properties of seafloor sediments off the coast of Southeastern Hainan, South China Sea

Geoacoustic parameters are essential inputs to sediment wave propagation theories and are vital to underwater acoustic environment and explorations of the sea bottom. In this study, 21 seafloor sediment samples were collected off the coast of southeastern Hainan in the South China Sea. The sound speed was measured using a portable WSD-3 digital sonic instrument and the coaxial differential distance measurement method. Based on the measured sound speed and physical properties, the acoustic impedance and the pore-water-independent index of impedance (IOI) were calculated in this study. Similar to the sound speed, the IOI values are closely related to the sediment physical properties and change gradually from the northwest to the southeast. The relations between IOI and physical properties were studied and compared to the relations between the sound speed and physical properties. IOI is better correlated to physical properties than sound speed. This study also uses an error norm method to analyze the sensitivity of IOI to the physical parameters in the double-parameter equations and finds that the most influential physical parameters are as follows: wet bulk density > porosity > clay content > mean particle size.

A facile approach to fabricate ZnO thin film based micro-cantilevers

In this study we report on the design, micro-fabrication and characterization of piezoelectric micro-cantilevers based on zinc oxide (ZnO) thin films. Array of micro-cantilevers are realized using silicon wet bulk micromachining process. ZnO films are very sensitive to nearly all chemicals, acids, base and even water. New unit process is developed to protect ZnO films, which utilizes wafer protection jigs. This jig allows tetra-methyl-ammonium hydroxide (TMAH) wet etching on single side of wafer, while protecting active devices on the other side. Highly c-axis oriented and room temperature deposited ZnO films are utilized for micro-cantilever fabrication. ZnO films used in this study have good crystalline quality with full width half maxima (FWHM) ~0.39°, grain size ~80nm and have minimal stress of ~41MPa. The micro-cantilever consists of Si/SiO2/Si3N4/Al/ZnO/Al multilayer stack for self-actuation of devices. Dynamic study is done using laser Doppler vibrometer. A customized relationship has been derived between resonance frequency and cantilever length considering multilayer structure. This inexpensive novel fabrication method provides flexibility to realize variety of other micro-electro-mechanical systems (MEMS) piezoelectric devices. The developed method is cost effective, easy, hassle free and may be preferred over deep reactive ion etching (DRIE) process.

Mercury evasion from a boreal peatland shortens the timeline for recovery from legacy pollution

Peatlands are a major source of methylmercury that contaminates downstream aquatic food webs. The large store of mercury (Hg) in peatlands could be a source of Hg for over a century even if deposition is dramatically reduced. However, the reliability of Hg mass balances can be questioned due to missing long-term land-atmosphere flux measurements. We used a novel micrometeorological system for continuous measurement of Hg peatland-atmosphere exchange to derive the first annual Hg budget for a peatland. The evasion of Hg (9.4 µg m−2 yr−1) over the course of a year was seven times greater than stream Hg export, and over two times greater than wet bulk deposition to the boreal peatland. Measurements of dissolved gaseous Hg in the peat pore water also indicate Hg evasion. The net efflux may result from recent declines in atmospheric Hg concentrations that have turned the peatland from a net sink into a source of atmospheric Hg. This net Hg loss suggests that open boreal peatlands and downstream ecosystems can recover more rapidly from past atmospheric Hg deposition than previously assumed. This has important implications for future levels of methylmercury in boreal freshwater fish and the estimation of historical Hg accumulation rates from peat profiles.

Characterization and Use of Construction and Demolition Waste from South of Brazil in the Production of Foamed Concrete Blocks

The main objective of this study was to evaluate the use of construction and demolition waste (CDW) from the Passo Fundo region of Rio Grande do Sul (RS), Brazil, in the development of aerated foamed concrete. This waste had not yet been characterized or even reused. CDW was processed (sieved only), characterized, and used as an aggregate, completely substituting natural sand. The influence of CDW granulometry and the amount of foam upon compressive strength, wet and dry bulk density, water absorption, and the air voids of concrete blocks were determined. Results showed that CDW has regular characteristics for the development of aerated foamed concrete. Compressive strength and density decreased as the amount of foam increased, while water absorption and air voids also increased. Also, CDW that was classified as coarse showed higher compressive strength. On average, CDW medium-sized particles had a higher air void content, while water absorption showed little variation with respect to granulometry. CDW residue from the region of study can be used as aggregate for the development of aerated foamed concrete. However, it must characterized before being used to guarantee the quality of the final product.

Prediction of sand mass and organic matter distribution via in situ measured wet sediment bulk density profile

The objective of the study is to develop a spatial prediction model of sand mass and organic matter distribution in an urban stormwater holding pond using in situ measured wet sediment bulk density profile data to spatially distinguish the most likely contaminated sediment deposit areas. The wet bulk density profiles of deposited sediment at 25 locations in the Berembang (Malaysia) stormwater holding pond were measured using a single-probe nuclear density gauge. The sand and organic matter compositions of the surface sediment sample, 5 cm thickness from the bed surface, were determined. Discriminant analysis (DA) was conducted to generate two Fisher’s linear discriminant functions for the prediction of sand mass and organic matter composition areas, respectively. The linear discriminant functions generated better area classifications of surface organic matter composition compared to the sand mass distribution using wet sediment bulk density data measured at more than 15 cm depth levels.

Estimating soil thermal diffusivity at different water contents from easily available data on soil texture, bulk density, and organic carbon content

This study provides an algorithm to estimate soil thermal diffusivity at any water content from data on soil texture, bulk density, and percentage of organic carbon. Models were trained on the dataset of 77 soil samples including silty clays, silty clay loams, silt loams, clay loams, loams, sandy clay loams, sandy loams, loamy sands, and sands. The ranges of sand, silt, and clay within the dataset were 1 – 97, 2 – 80, and 1 – 52%; wet bulk density varied from 860 to 1820 kg m −3 , organic carbon ranged from 0.1 to 6.5%. Thermal diffusivity of the undisturbed soil cores measured by the unsteady-state method was from 0.77 to 10.09 × 10 −7 m 2 s −1 . The dataset was split randomly into the training set of 67 samples and the test set of 10 samples; the procedure was repeated three times. Models were developed from the measured thermal diffusivity vs. water content curves. The experimental data points for each sample were described by a 4-parameter function. Parameters of average curves for different textural classes were also determined. Then regression equations were obtained to estimate the parameters of the thermal diffusivity vs. water content function for different soils: (i) from soil texture; (ii) from soil texture and bulk density; (iii) from soil texture and organic carbon; (iv) from soil texture, bulk density, and organic carbon. The test set data were used to evaluate the model performance. The normalised root mean square errors of the best-performing models were from 20 to 33% depending on soil information available.

Silicon Anisotropic Etching in Ternary Solution Composed of TΜΑΗ+Triton+NH2ΟΗ

Present work reports the anisotropic etching characteristics of silicon in various concentrations of tetramethylammonium hydroxide (TMAH) without and with addition of 10% hydroxylamine (NH2OH) and Triton X-100 ranging from ppb to ppm. The etch rate, undercutting at convex corners, and etched surface morphology are investigated in pure TMAH, TMAH+NH2OH, and different compositions of TMAH+NH2OH+Triton (i.e. ternary solution). High etch rate and undercutting are achieved in NH2OH-added 15 wt% TMAH, while 25 wt% TMAH + 10% NH2OH + 1 ppm Triton provided significantly less corner undercutting with reasonably good etch rate of Si{100}. This work is very useful for engineering applications for the fabrication of microstructures using silicon wet bulk micromachining for MEMS-based devices.

Modified TMAH based etchant for improved etching characteristics on Si{1 0 0} wafer

Wet bulk micromachining is a popular technique for the fabrication of microstructures in research labs as well as in industry. However, increasing the throughput still remains an active area of research, and can be done by increasing the etching rate. Moreover, the release time of a freestanding structure can be reduced if the undercutting rate at convex corners can be improved. In this paper, we investigate a non-conventional etchant in the form of NH2OH added in 5 wt% tetramethylammonium hydroxide (TMAH) to determine its etching characteristics. Our analysis is focused on a Si{1 0 0} wafer as this is the most widely used in the fabrication of planer devices (e.g. complementary metal oxide semiconductors) and microelectromechanical systems (e.g. inertial sensors). We perform a systematic and parametric analysis with concentrations of NH2OH varying from 5% to 20% in step of 5%, all in 5 wt% TMAH, to obtain the optimum concentration for achieving improved etching characteristics including higher etch rate, undercutting at convex corners, and smooth etched surface morphology. Average surface roughness (Ra), etch depth, and undercutting length are measured using a 3D scanning laser microscope. Surface morphology of the etched Si{1 0 0} surface is examined using a scanning electron microscope. Our investigation has revealed a two-fold increment in the etch rate of a {1 0 0} surface with the addition of NH2OH in the TMAH solution. Additionally, the incorporation of NH2OH significantly improves the etched surface morphology and the undercutting at convex corners, which is highly desirable for the quick release of microstructures from the substrate. The results presented in this paper are extremely useful for engineering applications and will open a new direction of research for scientists in both academic and industrial laboratories.

U.S. tanker transport: Current structure and economic analysis

With the advent of hydraulic fracturing, e.g. “fracking” in North America and United States policy changes on the export of crude oil and natural gas, it is anticipated that major structural changes will occur in the maritime transport of these commodities. The impact of these changes are global; however, regional transportation in North America is also expected to have profound impacts. This paper investigates these structural changes and the potential impact in the short-term and long-term effects on tanker shipping with data from tanker traffic in the major U.S. liquid bulk ports as well as crude oil and oil product movements recorded by the U.S. Energy Information Administration. We find a significant increase in U.S. oil and oil based product exports and a corresponding decline in imports in the recent years and the near future. The domestic market shows an increase in tanker traffic from the Gulf Coast to the East Coast of the U.S. Based on these current developments, four potential scenarios emphasize the growth or decline of tanker shipping (also tanker freight rates) connected to the U.S. waterborne wet bulk trades. Both public and private decision makers need to make delicate investment choices strongly tied to oil price variations. Considering the prospects on rising oil prices in the long-run, a significant downgrade of crude oil shipping and uprising oil product shipping are some fundamental results to be considered by key decision making units in the industry.

Letter to the editor: Critical assessments of the current state of scientific knowledge, terminology, and research needs concerning the ecological effects of elevated atmospheric nitrogen deposition in China

In a publication in Atmospheric Environment (http://dx.doi.org/10.1016/j.atmosenv.2015.10.081), Gu et al. (2015) estimated that “the total nitrogen (N) deposition in 2010 was 2.32 g N m−2 yr−1” in China. This value is comparable with previous estimations based on a synthesized dataset of wet/bulk inorganic N deposition observations, which underestimates the total N deposition since their algorithm (equations (2) and (3) in their paper) does not account for dry deposition of NH3, HNO3, NOx and wet/dry deposition of HONO and organic nitrogen (e.g. amines, amides, PAN). Indeed, Gu et al. (2015) mixed the terminology of wet/bulk deposition and total deposition. Another flawed assumption by Gu et al. (2015) is that all inorganic N in precipitation estimated by their algorithm originates from fertilizer and coal combustion. This is incorrect and almost certainly causes biases in the spatial and temporal distribution of estimated wet/bulk inorganic N deposition (Fig. 5 in their paper), further considering the fact that they neglected important N sources like livestock and they did not consider the nonlinearity between various sources and deposition. Besides the input data on N deposition, the model validation (Sect. 2.3.2) described in their paper also requires clarification because the detailed validation information about the time series of observational dataset versus modeling results was not given. As a result of these combined uncertainties in their estimation of N deposition and the lack of detail for model-measurement comparison, their estimates of the impacts of N deposition on carbon storage in Chinese forests may need further improvement. We suggest the clarification of the terminology regarding N deposition, especially for wet deposition, bulk deposition, gaseous and particulate dry deposition or total deposition since the accurate distinction between these terms is crucial to investigating and estimating the effects of N deposition on ecosystems.

Cereal rye cover crop effects on soil carbon and physical properties in southeastern Indiana

Cover crops can be a management practice used to improve soil health and increase resilience to extreme climate events in a typical midwestern corn–soybean (<i>Zea mays</i> L.–<i>Glycine max</i> L.) rotation. This study was conducted as part of a large regional project with a goal of studying how to make corn-based cropping systems more resilient to climate stresses. A field site was established in southeastern Indiana to study the effects of a cereal rye (<i>Secale cereale</i> L.) cover crop on soil physical and chemical properties in a no-till corn and soybean rotation. Soil measurements included water stable soil aggregates using the wet sieving method, bulk density and water retention using intact cores, and soil organic carbon (SOC) and total nitrogen (N). After four years of a cereal rye cover crop, wet soil aggregate mean weight diameter increased 55% when compared to the no cover control in the 0 to 10 cm (0 to 4 in) depth and 29% in the 10 to 20 cm (4 to 8 in) depth. Bulk density, water retention, SOC, and total soil N showed no change between cover crop treatments. This research shows that a cereal rye cover crop can increase water stable aggregation in a relatively short time, but changes in other physical and chemical properties are more difficult to detect.

Downward spread of smouldering peat fire: the role of moisture, density and oxygen supply

Smouldering fires in peatland are different from the flames in wildland fires. Smouldering peat fire is slow, low-temperature and more persistent, releasing large amounts of smoke into the atmosphere. In this work, we experimentally and computationally investigate the vertical downward spread of smouldering fire in a column of 30cm-tall moss peat under variable moisture content (MC) and bulk density. The measured downward spread rate decreases with depth and wet bulk density, and is ~1cmh−1 equivalent to a carbon emission flux of 200 tonnesday−1ha−1. We observe that downward spread increases as MC increases substantially at least inside the range from 10 to 70%, which is not intuitive and goes against the trend observed for the horizontal spread in the same peat. We also conduct one-dimensional computational simulations to successfully reproduce the experimental observations. The analysis shows that the spread rate increases with MC and decreases with density because smouldering spread is controlled by the oxygen supply. The volume of the porous peat expands when absorbing water, which reduces the density of organic matter and decreases the heat release rate. This shows that the widely assumed conclusion that the spread rate of wildfire decreases with MC is not universal when applied to smouldering fires.

Suspended matter and fluid mud off Alleppey, southwest coast of India

Time series measurements on suspended particulate matter (SPM) were made at one non-mud bank (M1) and two mud bank stations (M2 and M3) off Alleppey, south west coast of India. The mean SPM was low in surface (6.2 mg/l) and mid-depth (3.7 mg/l) waters and higher in bottom-depth waters (24.6 mg/l) of these stations, during both pre-monsoon and monsoon seasons. Near bed suspended sediment results indicated low SPM during July (0.042 g/l) and September (0.018 g/l) at M1, but very high SPM at M2 (9.2 g/l) and M3 (6.2 g/l) during July that decreased (M2: 0.033 g/l; M3: 0.1 g/l) again in September. Observations based on LISST-25X indicated that optical transmission (OT) was high (80–100%) in surface and mid-depth waters but decreased with increasing depth. Near bed waters at M2 and M3 stations showed ∼1 m thick fluid layer with 0% OT and with high particle volume concentrations (150–200 μl/l) during monsoon. Bottom sediments were clayey silts. Sediments of <63 μm fraction were skewed towards finer size at M1 but to coarser size at M2 and M3 stations during monsoon. The water content of the sediment decreased and wet bulk density increased at M2 and M3 stations, while it was the opposite at M1 station during the monsoon. Our results indicated the presence of fluid mud close to the bottom at M2 and M3 stations. As the wave height decreased from ∼3 m in May to 0.76 m in July, the dissipated wave energy probably liquefied, eroded and re-suspended the bottom sediment to form fluid mud. Upwelling currents may have been involved in the up keep and transportation of fluid mud. The suspended mud resettled at the bottom soon after the monsoon event.

Guar, jantar, wheat straw, and rice hull composts as replacements for peat in muskmelon transplant production

The demand for soilless media for vegetable transplant production is increasing. Economic constraints paired with concerns over the sustainability of peat mining have necessitated the replacement of peat with renewable and regionally abundant alternatives. The aim of this study was to develop from composts complete or partial substitutes for peat. Composted guar (Cyamopsis tetragonoloba), jantar (Sesbania aculeata), wheat (Triticum aestivum) straw, and rice (Oryza sativa) hulls adjusted to 10% air-filled porosity (AFP) were blended on a volumetric basis with peat moss at discrete levels (0–50%). Total water-holding capacity, shrinkage, dry and wet bulk density, pH, electrical conductivity, N, P, K, FE, B, and Zn concentrations of each compost, their blends, and a peat control were measured. The experimental media were used to grow muskmelon (Cucumis melo) plants in a greenhouse. Seed germination, shoot fresh weight, shoot height, leaf area, stem diameter, root length, and mineral nutrient concentrations of transplants were quantified. After transplanting in the field, the growth rates and yields were measured. Nonparametric regression was used to analyze the data. The physiochemical parameters measured for most of the experimental media fell within the recommended range for growing media; however, pH for all media exceeded the recommended range. Media-containing guar and jantar composts generally contained more nutrients than media-containing rice hull or wheat straw composts. Fresh weight, height, and root length were generally greater for seedlings grown in media-containing rice hull compost than for those grown in media-containing other composts. Seedlings grown in media-containing guar or jantar composts generally had greater tissue nutrient concentrations. All blends produced acceptable seedlings; however, the largest seedlings, and greatest post-transplant growth rate and yield were produced in media containing 30–50% rice hull compost.

Wedge Mode Propagation Characteristics of Triangular–shaped Surface Plasmon Waveguide

Abstract: In this paper, we investigate wedge mode propagation characteristics of a triangular-shaped surface plasmon waveguide. This structure consists of a thin metal layer deposited onto the surface of a triangular–shaped silicon waveguide which could be fabricated on a silicon–on–insulator wafer by wet–bulk micromachining. These elements are embedded in a dielectric medium (such as air) to form metal–dielectric interface and the surface plasmon wave propagates at the wedge of metal layer. The influence of structural parameters such as metal layer, height of silicon waveguide and effect of fabrication on the wedge mode propagation characteristics of the waveguide is analyzed by using numerical simulation.&#x0D; Keywords: V–shaped waveguide, Surface plasmon polariton, plasmonic waveguide.