Wide Clear Zone Research Articles

Product Optimization and Antimicrobial Efficiency of Starch-Based Active Packaging Film Prepared Using Amira (Plumbago Zeylanica) Root Extract

This study aimed to develop food packaging from cornstarch combined with methanol extract of Plumbago zeylanica root as antimicrobial agents. The antimicrobial activity of the extract was tested against three bacterial strains, namely, Staphylococcus aureus, Salmonella typhi, and Escherichia coli and one fungal strain called Aspergilla niger. Microorganism growth inhibition was examined by employing a zone of inhibition check on solid media. Two hundred microliters of assorted concentrations (200 mg/ml, 100 mg/ml, 50 mg/ml, and 25 mg/ml) of plant extracts were added into an eight-millimeter hole diameter employing a micropipette. Hence, 200 µl of 200 mg/ml extract inhibited 13.5, 8.75, 10.5, and 27 mm diameter for S. typhi, E. coli, S. aureus, and A. niger, respectively. The minimum inhibitory concentrations 1.25 mg/ml, 2.5 mg/ml, 1.25 mg/ml, and 0.625 mg/ml of crude extract utterly suppressed the growth of S. aureus, E. coli, S. typhi, and A. niger, respectively. Later on, the antimicrobial agent films and the control media were prepared by the casting method. The prepared antimicrobial packaging films exhibited inhibitory zones (a wide clear zone on solid media) for S. typhi and A. niger growth inhibition; however, inhibitions for E. coli and S. aureus were not effective. Antimicrobial activity decreased while decreasing the solubility of the film and antimicrobial concentration with increasing cornstarch content in the solution. The tensile strength of the films increased with increasing antimicrobial content in the solution. Higher antimicrobial inhibition activity was found at a 1.5 glycerol/starch ratio, 1.5 gram content of P. zeylanica, and 0.5 mm film thickness. Generally, the plasticized cornstarch antimicrobial packaging film combined with P. zeylanica extract had a significant effect on the growth of each selected microorganism and the physical properties of the material ( P < 0.05). A preprint of this research has previously been uploaded to the Addis Ababa University database (Yirdaw et al. 2018). In this section, only the summary and updated content of the research findings are presented.

Isolation and Optimization of Lipase Producing Bacteria from Oil-Contaminated Soils

This research aimed to isolate lipase-producing bacteria from soil samples contaminated with vegetable oil or petrol, and then optimize the conditions for lipase production. The bacteria that could be grown on tributyrin agar supplemented with 1% palm oil and produced a wide clear zone were selected. These selected bacterial isolates were tested for lipase activity, among them, the isolate PKRU-9 had the highest lipase activity. Then, the optimum conditions for lipase production of the PKRU-9 were optimized. The maximum lipase production was obtained when PKRU-9 was cultured in a basal medium containing 0.5% yeast extract as a nitrogen source and 0.5% soybean oil as a carbon source at 200 rpm. After cultivation for 54h, the maximum lipase production was reached. Treatment of wastewater contaminated with lipid of PKRU-9 was studied by culturing the bacterium in synthetic wastewater medium containing 1% palm oil, and in wastewater contaminated with fat. PKRU-9 was able to decrease the value of BOD5 by 74% and 90%, respectively comparing to the starting BOD5. The highest percent reduction of BOD5 was found on day 3 of cultivation. These results suggested that the PKRU-9 has the potential to be used for treating municipal wastewater contaminated with fat.

Growth and Survival of Lactic Acid Bacteria Isolated from Byproduct of Virgin Coconut Oil as Probiotic Candidate for Poultry

The main objective of this research is to investigate the potential of LABs isolated from processing byproduct of the VCO in in vitro conditions for use as probiotics in poultry. Forty eight LABs were isolated and four of them have been selected for further study i.e. Lh1, Lh2, Lh3 and Lh4. A series of tests carried out by studying the ability of bacteria to survive at 37 and 42°C, tolerance of LAB at pH 2, 0, 5, 7 and 7, 0 and tolerance to gastric juice as well as sensitivity to several antibiotics commonly was given to poultry. The survival of LABs was evaluated after 15, 30, 60, 90 and 120 and 300 min of incubation. The sensitivity test to antibiotics was performed by Muller Hinton's agar. All the bacteria showed tolerance and ability to grow at pH 5 and 7, but only Lh4 enabled to tolerate at pH 2. All of LAB can grow at gastric juice stimulated. Lh4 was not sensitive to all antibiotics (clear zones: 0.33 mm) but the other LABs were sensitive (clear zones: 5-12 mm). The conclusion of this research is the ability of LABs to grow in in vitro conditions varies. The Lh4 has demonstrated its ability to grow and the best survival with the OD (λ = 580) is 1.99 after 300 min of incubation at pH 2 and has shown the most resistant to all antibiotics tested with a wide clear zone 0.33 mm, hence potentially be used for probiotic in poultry.

Urban Roadside Safety

Roadside safety in rural environments has been the focus of considerable study, but direct application of this knowledge to the constrained urban environment has posed many challenges. Restricted right-of-way with a greater demand for functional use of the space adjacent to urban roads makes the maintenance of a wide clear zone impractical. This paper summarizes a corridor roadside crash analysis used to help identify urban roadside safety issues and illuminate possible solutions for attempting to mitigate objects in the roadside that have the potential to increase injury severity if hit. The paper focuses on arterial and collector-type facilities in urban areas with speed limits between 25 and 50 mph. The authors assessed corridors of urban roadside conditions and compared 6 years of historic crash data with roadside features. The goal of this effort was to identify potential configurations that posed a greater risk by the use of cluster-crash analysis. Locations with similar features without these companion crashes provided insight into prospective alternative treatments for roadside safety in urban environments. The higher-risk roadside locations identified by these approaches were referred to as urban control zones. The most commonly observed roadside crashes included locations in close lateral proximity to the curb face or lane edge, lane merge locations, select auxiliary lane treatments, sidewalk buffer configurations with rigid objects in close proximity to the travelway, driveway and intersection locations, high-cluster-crash locations, and other common roadside crash conditions.

Sexual dimorphism in the compound eye of the moth Operophtera brumata (Lepidoptera, Geometridae)

Abstract. Brachyptery in female moths is a common phenomenon. This article examines the eyes of the moth Operophtera brumata, in which only the males have wings. Both sexes possess eyes of the superposition type, have facets with corneal nipples, and exhibit eyeglow, but the eye of the male has 2174 facets, measures 725 μm in diameter, and has a clear zone of 112‐μm width. That of the female has 1352 facets, measures 557 μm across, and has a 77‐μm‐wide clear zone. There were no significant differences in rhabdom diameters (10 μm) and tracheal sheath development, but male rhabdoms were significantly longer (85 vs. 65 μm). Dark/light adaptational changes manifested themselves in the positions of the distal screening pigment granules: between the cones during darkness and into the clear zone during light adaptation. The combination of a larger radius of curvature, wider clear zone, and longer rhabdoms gives the males a sensitivity at least twice that of the female. The narrower interommatidial angles of the male (2.8° vs. 3.2°) together with the well‐developed tracheal rhabdom sheaths, furthermore, provide the eyes of the males with better resolution. Finally, eye‐glow intensity in males diminishes considerably faster in light than it does in females. The differences between males and females appear to reflect their different roles: males begin to search after sunset in and around stands of trees for the pheromone‐emitting females, which sit on the trunk of the tree under which they had emerged from their pupal case. Flying males encounter rapid light intensity changes and have to evade obstacles and enemies. The females are considerably more sedentary, but once mated, still seek suitable oviposition sites long after the males have ceased searching for them. During this activity, the females also need visual sensitivity and acuity, but less than the actively flying males.

Safety and cost-effectiveness of clear zones in Iran

This paper examines different clear-zone improvement alternatives in rock cuts, and compares the likely effect on safety and construction costs. Where a roadway passes through rock cuts, the construction cost of providing the clear zone is very high. This paper is based on research that demonstrates a method for selecting the appropriate clear zone in rural two-lane highways in Iran based on the site and traffic conditions expected at the site. A method is described for determining the rock-cut width that best balances the cost of construction with the improvements in safety that would result from a wider clear zone in the rock cut. The objective of this study is to quantify the societal cost of rock-face accidents, so that the costs and benefits associated with different clear-zone policies can be explicitly addressed during the preliminary design process. This study shows that the need for extra clear-zone width in steep and bendy routes (specially with external curves of less than 195 m radius) is more critical than that for straight and level ones. The existence of external horizontal curves simultaneously with severe longitudinal slopes increases the probability of vehicles’ encroachment by as much as eight times in comparison with straight and level routes. An interesting point to note is that, by providing wider lanes, the need for extra clear-zone width is reduced dramatically.

Sexual dimorphism and light/dark adaptation in the compound eyes of male and female Acentria ephemerella (Lepidoptera: Pyraloidea: Crambidae)

In the highly sexual-dimorphic nocturnal moth, Acentria ephemerella Denis & Schiffermuller 1775, the aquatic and win- gless female possesses a refracting superposition eye, whose gross structural organization agrees with that of the fully-winged male. The possession of an extensive corneal nipple array, a wide clear-zone in combination with a voluminous rhabdom and a reflecting tracheal sheath are proof that the eyes of both sexes are adapted to function in a dimly lit environment. However, the ommatidium of the male eye has statistically significantly longer dioptric structures (i.e., crystalline cones) and light-perceiving elements (i.e., rhab- doms), as well as a much wider clear-zone than the female. Photomechanical changes upon light/dark adaptation in both male and female eyes result in screening pigment translocations that reduce or dilate ommatidial apertures, but because of the larger number of smaller facets of the male eye in combination with the structural differences of dioptric apparatus and retina (see above) the male eye would enjoy superior absolute visual sensitivity under dim conditions and a greater resolving power and ability to detect movement during the day. The arrangement of the microvilli in the rhabdom of both genders suggests that their eyes are polarization-sensitive, an ability they would share with many aquatic insects that have to recognize water surfaces. Although sexual recognition in A. ephe- merella is thought to chiefly rely on pheromones, vision must still be important for both sexes, even if the females are wingless and never leave their watery habitat. Females swim actively under water and like their male counterparts, which fly above the surface of the water, they would have to see and avoid obstacles as well as potential predators. This, together with a small incidence of winged females, we believe, could be the reason why the eyes of female A. ephemerella are less regressed than those of other sexually dimorphic moths, like for instance Orgyia antiqua. Another, but difficult to test, possibility is that male and female A. ephemerella have diverged in their behaviour and habitat preferences less long ago than other sexually dimo rphic moths.

The compound eye of Orgyia antiqua (Lepidoptera: Lymantriidae): Sexual dimorphism and light/dark adaptational changes

Structure and photomechanical changes upon light/dark adaptation in the superposition compound eyes of the highly sexu- ally dimorphic Orygia antiqua were studied by light and electron microscopy. The eyes of the fully winged male differ from those of the wingless, sedentary female in several respects: they are significantly larger, display a more regular ommatidial array, have a wider clearzone and possess a much more substantial tracheal tapetum. However, the eyes of the female exhibit more pronounced photomechanical changes upon light/dark adaptation than those of the male. We believe that for females, on account of their limited mobility, it is necessary that their eyes can cope with widely fluctuating brightnesses, but that visual sensitivity and resolving power are less important to them than to the actively flying males. Although the latter may be attracted to the females by pheromones, males in their diurnal searches will have to visually avoid obstacles and predators. Moreover, because of their ability to fly, males can seek shelters or shaded areas and unlike the sedentary females avoid prolonged exposures to potentially hazardous light levels. This could explain why the eyes of the females exhibit more pronounced photomechanical responses to changes in ambient light lev- els.

Safety and cost-effectiveness of clear zones in Iran

This paper examines different clear-zone improvement alternatives in rock cuts, and compares the likely effect on safety and construction costs. Where a roadway passes through rock cuts, the construction cost of providing the clear zone is very high. This paper is based on research that demonstrates a method for selecting the appropriate clear zone in rural two-lane highways in Iran based on the site and traffic conditions expected at the site. A method is described for determining the rock-cut width that best balances the cost of construction with the improvements in safety that would result from a wider clear zone in the rock cut. The objective of this study is to quantify the societal cost of rock-face accidents, so that the costs and benefits associated with different clear-zone policies can be explicitly addressed during the preliminary design process. This study shows that the need for extra clear-zone width in steep and bendy routes (specially with external curves of less than 195 m radius) is more critical than that for straight and level ones. The existence of external horizontal curves simultaneously with severe longitudinal slopes increases the probability of vehicles' encroachment by as much as eight times in comparison with straight and level routes. An interesting point to note is that, by providing wider lanes, the need for extra clear-zone width is reduced dramatically.

Features of the clear zone of odontoclasts in the Chinook salmon (Oncorhynchus tshawytscha)

This study aims to clarify the features of the clear zone of odontoclasts on shedding teeth of a teleost fish, Chinook salmon, Oncorhynchus tshawytscha (Walbaum), using a light microscope to determine the orientation between a cell body and a resorptive lacuna, followed by transmission electron microscopy. Ultrathin sections of LR White embedded material were incubated in rabbit anti-actin polyclonal antibody and then were incubated with 15 nm gold-conjugated goat anti-rabbit IgG. The clear zones of odontoclasts showed a variable structure with electron-dense structures on sections, but distinct clear zones were not always seen on odontoclasts. In odontoclasts sectioned in the direction perpendicularly to the surface of a resorptive lacuna, some cells showed a wide clear zone, but two types of clear zones were usually observed: a part composed of some cytoplasmic processes and one composed of several complicatedly interwoven processes. Gold particles were localized on the clear zones, especially in electron-dense structures; very few gold particles were detected in ruffled borders. These results show that the clear zone of odontoclasts in Chinook salmon contains actin. Our results suggest that the clear zone of an odontoclast in Chinook salmon is not always a wide annular structure.

Safety and Cost-Effectiveness of Clearzones in Rockcuts

Clearzones are a feature of modern highways that have a dramatic impact on roadside safety. The purpose of these unobstructed spaces is to provide an area where an errant vehicle can safely stop or the driver can regain control of the vehicle without striking a hazardous object like a tree or utility pole. Many clearzone alternatives (e.g., removing trees, installing traversable culvert openings, and installing guardrails in front of untraversable hazards) are relatively inexpensive in comparison to other roadway construction costs. Roadways passing through rockcuts present an unusual case where the construction cost of providing the clearzone is very high. This article examines different clearzone alternatives in rockcuts and compares the likely effect on safety and construction costs. A method is described for determining the rockcut width that best balances the cost of construction with the improvements in safety that would result from a wider clearzone in the rockcut.

NGF receptor immunoreactivity in rat brain: topographic distribution and response to entorhinal ablation.

Nerve growth factor receptor (NGFR) immunoreactivity was distributed in neuronal cell bodies, axons and/or dendrites of cholinergic and non-cholinergic structures of the rat brain. The dentate gyrus of normal animals showed immunostained fibers mainly in the supragranular band, whereas following entorhinal ablation a greater density of immunostained fibers appeared in the outer molecular layer and a wider clear zone was apparent in the inner molecular layer. The NGFR-positive fibers followed the pattern of reorganization of septal fibers visualized with acetylcholinesterase staining. The results suggest that the NGF/NGFR may have a role in reorganization of septal fibers following entohinal lesion.

The Refractive Index Gradient in the Crystalline Cones of the Eyes of A Euphausiid Crustacean

ABSTRACT The eyes of the euphausiids, a group of malacostracan Crustacea, show a remarkable similarity to the superposition (Exner, 1891) eyes of moths. In both groups the eye has an outer layer of crystalline cones, a wide clear zone, and a layer of rhabdomes beneath it, whose radius of curvature is about half that of the eye itself (Fig. 2 a). We demonstrated recently that image formation in these eyes is indeed performed by a refracting superposition mechanism (Land, Burton & Meyer-Rochow, 1979), as supposed by Chun (1896). That is to say, light is bent by the crystalline cones in such a way that a ray reaching the outer surface of a cone, and making an angle α with the cone axis, is bent in the cone through an angle 2α (Fig. 1). This is the condition necessary if all parallel rays are to be brought to a focus in the rhabdome layer, where an erect image is produced (see Horridge, 1975). This mechanism, shared by moths, fireflies and some other beetles, is not the same as that of the decapod shrimps and prawns, where essentially the same trick is performed not by refracting cones, but by mirrors (Vogt, 1977; Land, 1978). Kampa (1965) proposed that the euphausiid eye was basically of the apposition type, with the cones funnelling light down light guides into the rhabdomes. However, the cones send light, as noted above, and the light-guides are not present (Meyer-Rochow & Walsh, 1979).

Adaptationserscheinungen in den komplexaugen von Gyrinus natator L. (Coleoptera : Gyrinidae)

The rhabdom of the compound eye of the whirligig beetle Gyrinus natator is continuous throughout, with a distal section formed by the rhabdomere of the retinula cell 1, and a proximal section formed by the rhabdomeres of the cells 2–7, plus the basal cell 8. The dorsal and the ventral eyes, although structurally similar, differ in the shape of the distal rhabdomere and the lengths of the various components of the eye. In course of the adaptation to darkness, the length of the cell 1 rhabdomere is increased by 50% in the dorsal eye as compared with 80% in the ventral eye. The crystalline tract is reduced to one-fourth in the dorsal eye, but it is completely reduced in the ventral eye. Therefore the space between the dioptric system and the basal part of the rhabdom is not only the result of the reduction of the crystalline tract but also, in a high proportion, of the elongation of the rhabdomere 1. This is documented by the proximal displacement of the entire zone of the basal rhabdom and of the changing shape of the basement membrane. As there is no screening pigment between the dioptric system and the basal part of the rhabdom in the dark-adapted state, the enlarged space represents a clear zone. Since a wide clear zone allows light from several facets to affect a particular rhabdom, the light sensitivity is probably increased. The displacement of the basal section of the rhabdom represents a mechanism of adaptation not previously described. Under conditions of adaptation to light, the basement membrane in both the dorsal and ventral eyes is convexly arched (as the cornea) into the capsule of the eye. Under condition of adaptation to darkness, the basement membrane of the ventral eye is evenly stretched, whereas in the dorsal eye it is convexly arched into the head capsule. In the course of adaptation to darkness, the screening pigments of the primary pigment cells are shifted distally. This leads to an enlarged aperture. The pigments of the secondary pigment cells are then placed in the terminal cell areas. This produces the pigment-free clear zone of a superposition-eye, which is penetrated only by the thin rhabdomere 1. The question as to what extent the beetle is able to use the principles of both an apposition- and a superposition-eye is raised. In my experiments, a selective adaptation to green or UV light was not detectable. The probability of perception of polarized light also seems to be low.

The eye of Anoplognathus (Coleoptera, Scarabaeidae)

The night flying scarabaeid beetle Anoplognathus provides an example of a dark-adapted clear-zone compound eye in which rays from a distant point source, entering by a large patch of facets, are imperfectly focused upon the receptor layer. The optical system of the eye was investigated by six methods, all of which give similar results: (1) ray tracing through structures of known refractive index, (2) measurement of visual fields of single receptors, (3) measurement of the divergence of eyeshine, and (4) of the optomotor response to stripes of decreasing width, and (5) by direct observation of distribution of light within the eye. Finally (6) anatomically there is no single plane upon which an image could be focused. In each ommatidium, beneath the thick cornea, with its short corneal cone, lies a non-homogeneous crystalline cone (range of r. i. 1.442-1.365) that is significant in partially focusing rays across the wide clear zone (340 μm) in the dark-adapted eye. On the proximal side of the clear zone the rhabdoms form 7-lobed columns, isolated from each other over half their length by a tracheal tapetum. In the light-adapted eye the cone cells extend to form a crystalline tract (70-90 μm long) which is sur­rounded by dense pigment, and the optical path across the clear zone is completed by retinula cell columns that are of higher density than the surrounding cells. Pigment movement upon adaptation takes about 10 min to complete. Dark adaptation can be induced only at night on account of a strong diurnal rhythm. Eyeshine can be seen in the dark-adapted eye so long as the distal pig­ment leaves free the tips of the crystalline cones. Eyeshine falls to 50% at an angle of 12° from the direction of a parallel beam shining on the eye, as is consistent with a partial focus in which the distribution of light on the receptor layer is 18°-24° wide at the 50% contour. This distribution was confirmed by direct examination of the inside of the eye and by measure­ment of receptor fields as follows. The mean acceptance angle for 13 light-adapted units was 12.57° ± 1.97° s. d. and that of 10 dark-adapted ones 20.3° ± 3.36° s. d. The sensi­tivity to a point source on axis is increased at least 1000 fold by dark adaptation. Rays traced through a scale drawing of the eye, with refractive index measured for each component, show how the eye as a whole comes to be partially focused, and predicts an acceptance angle of 12° in the light-adapted and 20°-24° in the dark-adapted eye. In optomotor experiments dark-adapted Anoplognathus does not respond to stripes narrower than 18° repeat period, but light-adapted beetles respond down to 10°. The optomotor experiments also show a 1000 fold increase in sensitivity when dark-adapted at night. The eye has poor acuity that goes with wide visual fields of its recep­tors, and this is surprising when other excellently focused clear zone eyes are known. A possible compensation for the poor acuity is that the aperture of the eye can be larger, so that sensitivity although only to large objects, is that much increased.

The superposition eye of skipper butterflies

1. The anatomy of the eye is described in seven representative genera of Australian Hesperioidea. Between the crystalline cones and the long rhabdom is a wide clear zone crossed by narrow extensions of the retinula cells. The distal pigment remains between the cones even in daylight. 2. No evidence of functional light guides crossing the clear zone could be found. 3. A real erect image is formed on the receptor layer. The acuity and origin of this image were investigated by several methods. 4. The angular sensitivity curve of the receptors is 6 to 8°wide at the 50% sensitivity contour. 5. Optomotor experiments with stripes of differing widths show that the angular sensitiv­ity of the receptors is fully utilized behaviourally, and that the eye functions in relatively dimlight. Adaptation changes are small. 6. A parallel beam falling on the eye reaches a single receptor via a circular patch of facets subtending about 30° at the centre of the eye. This was directly demonstrated by recording from a retinula cell and stimulating the eye by a moveable slit of parallel rays. This also demonstrates the wide acceptance angle of the exposed ends of the rhabdom columns. 7. When the eye is illuminated by a parallel beam, light is reflected back out of the eye. All the reflected light is contained in an angle of ±5° to the incident beam, although it enters and emerges via the large patch of facets mentioned above (6). Again, no effects of adaptation were observed. 8. The relation between the direction in which a ray enters the optical system of the cornea and cone and the direction it leaves was measured directly by a rotatable microscope of narrow aperture. 9. The mechanism by which the optical system forms the erect image on the receptor layer was demonstrated by tracing rays through scale drawings of the components. To do this the refractive index was measured in all components. The corneal surface acting as a lens forms the first image within the cone. The crystalline cone is non-homogeneous and acts as second lens in each ommatidium. 10. The skipper eye therefore illustrates Exner’s superposition principle, and it does so in daylight.

Differentiation of Enzyme Coagulants on Casein-Agar Gels

Enzyme coagulants were differentiated on pH 6.85 casein-agar gels. Calf rennet extracts produced primary and secondary precipitate zones separated by a wide clear zone in 24 hours. Swine pepsin produced no visible change or a slight primary zone of smaller diameter. Coagulants from Endothia parasitica and Mucor pusillus var. Lindt produced single zones of variable intensities. The fungal enzymes tended to clear the agar behind the zone. A substance diffusing ahead of the zone from fungal coagulants redissolved the primary rennet zone diffusing from adjacent wells. Characteristics of secondary precipitate zones detected less than 1% of either fungal enzyme in rennet, pepsin, or 50% rennet-pepsin blends. Rennet-pepsin blends with more than 20% pepsin had weak secondary precipitate zones. No secondary zones appeared when pepsin exceeded 60%.

The eye of Dytiscus (Coleoptera)

The eye of Dytiscus (Coleoptera) has rhabdomeres at three different levels. The crystalline threads stretch from the ends of the crystalline cones only as far as the distal layer of rhabdomeres. There is one distal rhabdo-mere per ommatidium, and in this system the ommatidia are anatomically separate. Between the distal rhabdomere and the rhabdomeres of the next six retinula cells is a wide clear zone in which light entering by one facet could possibly reach deep rhabdomeres of a different ommatidium. Of the six proximal rhabdomeres, four have rhabdomere tubules which lie horizontal with reference to the normal posture, the other two having vertically oriented tubules. The eighth cell, with nucleus near the basement membrane, has a small rhabdomere. All eight retinula cells have axons and there is no other class of axons in the eye.