Preliminary analysis of cryopreservation of Dendrobium Bobby Messina orchid using an encapsulation-dehydration technique with Evans blue assay

In vitro grown protocorm-like bodies (PLBs) of Dendrobium Bobby Messina hybrid were cryopreserved in liquid nitrogen (LN) at -196°C by an encapsulation-dehydration technique. PLBs (1 to 2 and 3 to 4 mm) were precultured in half strength semi-solid MS media supplemented with six different concentrations of sucrose (0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 M). The PLBs were then encapsulated to form the beads in halfstrength liquid MS media supplemented with different concentrations of sodium alginate (2.5, 3.0 and 3.5%). The beads were placed in 2 ml cryovials and plunged into LN for 24 h. The beads were then thawed in a 40°C water bath for 90 s and were placed in recovery media composed of half strength semisolid MS media supplemented with 2% sucrose for four days under dark condition. After 12 days, the Evans blue dye assay was carried out to determine the viability of the PLBs. The highest viability was found in 1 to 2mm PLBs precultured in half strength semi-solid MS media supplemented with 1.0 M sucrose and encapsulated in 2.5% sodium alginate. Biochemical content analyses (chlorophyll, total soluble protein and peroxidase activities) were done to investigate the physiological responses of the PLBs after cryopreservation.Key words: Orchid, protocorm-like bodies, Dendrobium Bobby Messina, encapsulation-dehydration

In vitro induction and proliferation of protocorm-like bodies (PLBs) from leaf segments of Phalaenopsis bellina (Rchb.f.) Christenson

An in vitro culture procedure was established to induce protocorm-like bodies (PLBs) from leaf segments of the Phalaenopsis bellina (Rchb.f.) Christenson directly from epidermal cells without intervening callus on ½ strength modified Murashige and Skoog (MS) (in Physiol Plant 15:473–497, 1962) medium supplemented with 1-Naphthaleneacetic acid (NAA; 0, 0.1, 1 mg/l) and Thidiazuron (TDZ; 0, 0.1, 1, 3 mg/l). The best response was established at 3 mg/l TDZ which induced 78% of leaf segments to form a mean number of 14 PLBs per explant after 16 weeks of culture. No PLBs were found when leaf segments were cultured on ½ strength modified MS media supplemented with 0.1 and 1 mg/l NAA. The best induction percentage for auxin: cytokinin combination was at the combination of NAA and TDZ at 1.0 and 3.0 mg/l which gave 72% induction with 9 PLBs per explant. Semi-solid ½ strength MS and liquid Vacin and Went (VW) (in Bot Gaz 110:605–613, 1949) medium were used in order to find the highest survival and number of PLBs proliferation after 3 months in culture. Half strength MS showed an average of 9 PLBs in comparison with VW with an average of 5.3 PLBs per explants. Histological observations revealed that the regenerated PLBs were generally formed from the epidermal layers of the posterior regions of the leaf segments. Scanning electron micrograph of PLBs showed the origin of newly formed PLB from the peripheral region of leaf segments

Dry Sliding-Friction and Wear Behavior of Hot-Extruded Al6061/Si3N4/Cf Hybrid Metal Matrix Composite.

The effects of reinforcement addition and hot extrusion on the microstructures, micro hardness, friction, and wear behavior of aluminium (Al) hybrid composite were investigated. Al6061 dispersed with electroless nickel-coated Si3N4 (6wt.%) and copper-coated carbon fiber (Cf) (1wt.%) hybrid composites was developed through stir casting followed by hot extrusion. Optical micro structural studies confirmed that the size of reinforcements decreased, and their orientations were in the extrusion direction. The decrease in the grain size (29%) of hybrid composites was larger than that in the grain size of matrix alloys under hot-extruded conditions. The synthesized hot-extruded Al6061 hybrid composite exhibited a lower coefficient of friction (51%) and high wear resistance (39%) compared with the hotextruded Al6061base alloy

Wear resistant carbon fiber reinforced Stellite alloy composites

Stellite alloys are a family of cobalt-based superalloys that are the main engineering materials used for severe corrosion, wear and high temperature environments. These alloys are strengthened by various carbides. However, the presence of carbides can cause many problems although they are main agents for wear resistance. This research attempts to develop a class of novel composite materials which substitute carbon of Stellite alloys with carbon fiber, aiming to minimize the disadvantageous effects of carbides in the alloys. Two types of carbon fiber, plain carbon fiber and nickel-coated carbon fiber, are employed in the composites. The new materials are fabricated using hot isostatic pressing (HIP) technique. The microstructures of these composites are analyzed to investigate if any carbides are induced due to incorporating carbon fibers. The tribological properties of these new composites are characterized on a pin-on-disk tribometer. The experimental results show that the developed composites exhibit better wear resistance than that of medium-carbon Stellite alloys and comparable wear resistance to that of high-carbon Stellite alloys. \ua9 2013 Elsevier Ltd.Peer reviewed: YesNRC publication: Ye

Novel wear-resistant materials \u2013 Carbon fiber reinforced low-carbon Stellite alloy composites

This paper reports the design and development of a class of new composite materials, which are low-carbon Stellite alloy matrices reinforced with carbon fibers. The focus of the research is to compare the different effects of carbon fibers versus carbides on Stellite alloys. Stellite 25 was selected as the matrix because of its very low carbon content (0.1 wt.%), thus minimal carbide volume fraction. The composite specimens are fabricated using the hot isostatic pressing and sintering techniques. The microstructures of the specimens are examined with optical microscopy in order to identify the possible carbide formation from the carbon fibers. The material characterization of the specimens is achieved through hardness test, sliding wear test and corrosion test. These novel materials exhibit superior properties compared to existing Stellite alloys and are expected to spawn a new generation of materials used for high temperature, severe corrosion, and wear resistant applications in various industries.Peer reviewed: YesNRC publication: Ye

A new composite material-low-carbon Stellite alloy reinforced with nickel-coated carbon fibers

A group of nickel-coated carbon fiber reinforced Stellite 25 composites are produced using the hot isostatic pressing technique. The focus of this research is on obviating the problems related to the presence of carbides in Stellite alloys by substituting carbides as the main strengthening agent in Stellite alloys with nickel-coated carbon fibers. The principal reason for selecting Stellite 25 is because of its low carbon content and thereby relatively carbide free microstructure. The nickel coating is intended to eliminate any chance of carbide formation due to the possible reaction between carbon fibers and the matrix alloying additions. The tribomechanical and corrosion properties of the composites are characterized. The results show that the composites exhibit better corrosion resistance than medium-carbon Stellite alloys. The addition of carbon fibers into Stellite 25 improves its hardness and tribological properties. The wear rates of the composites are lower than that of medium-carbon Stellite alloys and comparable with that of high-carbon Stellites. \ua9 The Author(s) 2012.Peer reviewed: YesNRC publication: Ye

Precision Horticulture: Application of Optical Sensor Technology for Nitrogen Monitoring Status in Cocoplum, a Native Landscaping Plant

Cocoplum (Chrysobalanus icaco) is an ecologically significant native species to Southern Florida. Application of precision agriculture technologies such as optical sensors reduces the cost of over-fertilization and nutrient runoff. The aim of this work was to establish a base line sensor value for fertilizer treatment in cocoplum by monitoring chlorophyll content using the Soil Plant Analytical Development (SPAD), atLEAF, and Normalized Difference Vegetation Index (NDVI) sensors. Initial slow-released fertilizer treatment 8N-3P-9K was used at 15 g (control), 15 g (supplemented with +15 g × 2; T1), 15 g (+15 g; T2), 30 g (+15 g × 2; T3), 30 g (+15 g; T4), and 45 g (+15 g × 2; T5). Evaluations were conducted at 0 (base reading), 30, 60, 90, 120, 150, and 180 days after treatment. Growth parameters, optical non-destructive chlorophyll meters, leaf and soil total nitrogen and total carbon, and total nitrogen of leachate were analyzed. The results demonstrated that the treatment using 30 g slow-released fertilizer (8N-3P-9K) supplemented twice with 15 g in November and March after the first fertilization in October provided the least contamination through runoff while still providing adequate nutrients for plant growth compared to higher fertilizer concentrations. These results demonstrate that the highest treatment of nitrogen can cause considerable losses of N, causing extra costs to producers and environmental damage due to the flow of nutrients. Thus, techniques that help in N monitoring to avoid the excessive use of nitrogen fertilization are necessary. This study can serve as a basis for future research and for nurseries and farms, since it demonstrated from the monitoring of the chlorophyll content by optical sensors and by foliar and substrate analysis that lower treatments of nitrogen fertilization are sufficient to provide nutrients suitable for the growth of cocoplum plants

A cryopreservation protocol for ex situ conservation of terrestrial orchids using asymbiotic primary and secondary (adventitious) protocorms

© 2015, The Society for In Vitro Biology. In a bid to better conserve endangered terrestrial orchids, we detail cryogenic research using a widely distributed terrestrial orchid, Caladenia latifolia, as a model species for development of cryopreservation for primary (seed generated) and secondary (adventitious) protocorms. Primary protocorm cryopreservation (using droplet vitrification) involved a number of experimental lines of inquiry: investigation of a suitable plant vitrification solution (PVS) by comparing three variants of a standard PVS (2, 3 and 4), determining the most suitable primary protocorm developmental stage for successful cryopreservation, testing the effectiveness of a preculture medium treatment prior to cryopreservation, and investigating temperature preconditioning at the preculture stage as well as different components of the recovery medium. Primary protocorms were generated using asymbiotic in vitro germination media developed by the authors specifically for the test species (half-strength MS macroelements and microelements with 5% (v/v) fresh filter sterilized coconut water). Secondary protocorms were propagated using an in vitro proliferation medium (½ MS with 5 µM a-naphthaleneacetic acid + 2 µM 6-benzylaminopurine). A modified preconditioning step was developed, involving incubation on ½ MS with 0.2 M raffinose for 48 h at 15°C instead of 20°C. The standard recovery medium (½ MS 1 µM zeatin + 0.5 µM gibberellic acid) was replaced after the first week following warming from liquid nitrogen (LN), with asymbiotic germination medium (½ MS + 5% (v/v) coconut water) for the remainder of the recovery phase. This new step increased the survival of primary protocorms from 68 to 85%. The average post-cryostorage regeneration of plants from primary protocorms increased from 17 to 48% after a 6-wk incubation. A similar protocol increased the survival of secondary protocorms from 63 to 84%. Regeneration of plants from secondary cryostored protocorms increased from 11 to 26% after 14 wk. The protocols developed here provide a useful template for advancing cryoconservation of other orchid taxa, particularly rare and threatened species