Preserving frozen stallion sperm on dry ice using polymers that modulate ice crystalization kinetics

Cryopreserved semen is routinely shipped in liquid nitrogen. Dry ice could serve as an alternative coolant, however, frozen storage above liquid nitrogen temperatures (LN2, -196 °C) may negatively affect shelf-life and cryosurvival. In this study, we determined critical temperatures for storage of cryopreserved stallion sperm. We evaluated: (i) effects of cooling samples to different subzero temperatures (-10 °C to -80 °C) prior to storing in LN2, (ii) stability at different storage temperatures (i.e., in LN2, dry ice, -80 °C and -20 °C freezers, 5 °C refrigerator), and (iii) sperm cryosurvival during storage on dry ice (i.e., when kept below -70 °C and during warming). Furthermore, (iv) we analyzed if addition of synthetic polymers (PVP-40, Ficoll-70) modulates ice crystallization kinetics and improves stability of cryopreserved specimens. Sperm motility and membrane intactness were taken as measures of cryosurvival, and an artificial insemination trial was performed to confirm fertilizing capacity. We found that adding PVP-40 or Ficoll-70 to formulations containing glycerol reduced ice crystal sizes and growth during annealing. Post-thaw sperm viability data indicated that samples need to be cooled below -40 °C before they can be safely plunged and stored in LN2. No negative effects of relocating specimens from dry ice to LN2 and vice versa became apparent. However, sample warming above -50 °C during transport in dry ice should be avoided to ensure preservation of viability and fertility. Moreover, addition of PVP-40 or Ficoll-70 was found to increase sperm cryosurvival, especially under non-ideal storage conditions where ice recrystallization may occur.

Field Comparison of Carbon Dioxide Source with Biogents Sentinel-2 and Pro Traps for Adult Aedes Mosquito Surveillance

The BG Sentinel-2 (BGS-2) and BG-Pro traps (BGS-2 configuration) were compared for their effectiveness to collect Aedes vectors and related nuisance mosquitoes in north central Florida during 2022. Traps were baited with either dry ice pellets, pressurized carbon dioxide (CO2) gas, or the novel BG yeast-derived CO2 generator. Additionally, each trap was fitted with the BG Sweetscent lure. Sixteen species were collected including Aedes albopictus and Ae. aegypti, which accounted for about 20% of the collections. The BGS-2 collected more mosquitoes compared to the BG-Pro, but the relative percent abundance of each species to total collection from each trap type was similar. Overall mosquito abundance was significantly greater in both trap types baited with dry ice compared with the other CO2 sources. Significantly more Ae. albopictus were collected from BGS-2 traps baited with dry ice than all other CO2 and trap configurations. Lastly, we did not observe any significant differences in Ae. aegypti abundance between trap type or CO2 source.

Repurposing dried blood spot device technology to examine bile acid profiles in human dried fecal spot samples

Dried blood spot (DBS) analysis has existed for >50 years, but application of this technique to fecal analysis remains limited. To address whether dried fecal spots (DFS) could be used to measure fecal bile acids, we collected feces from five subjects for each of the following cohorts: 1) healthy individuals, 2) individuals with diarrhea, and 3) Clostridioides difficile-infected patients. Homogenized fecal extracts were loaded onto quantitative DBS (qDBS) devices, dried overnight, and shipped to the bioanalytical lab at ambient temperature. For comparison, source fecal extracts were shipped on dry ice and stored frozen. After 4 mo, frozen fecal extracts and ambient DFS samples were processed and subjected to targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics with stable isotope-labeled standards. We observed no differences in the bile acid levels measured between the traditional extraction and the qDBS-based DFS methods. This pilot data demonstrates that DFS-based analysis is feasible and warrants further development for fecal compounds and microbiome applications.NEW & NOTEWORTHY Stool analysis in remote settings can be challenging, as the samples must be stored at -80°C and transported on dry ice for downstream processing. Our work indicates that dried fecal spots (DFS) on Capitainer quantitative DBS (qDBS) devices can be stored and shipped at ambient temperature and yields the same bile acid profiles as traditional samples. This approach has broad applications for patient home testing and sample collection in rural communities or resource-limited countries.

Preservation of exhaled breath samples for analysis by off-line SESI-HRMS: proof-of-concept study

Secondary electrospray ionization-high resolution mass spectrometry (SESI-HRMS) is an established technique in the field of breath analysis characterized by its short analysis time, as well as high levels of sensitivity and selectivity. Traditionally, SESI-HRMS has been used for real-time breath analysis, which requires subjects to be at the location of the analytical platform. Therefore, it limits the possibilities for an introduction of this methodology in day-to-day clinical practice. However, recent methodological developments have shown feasibility on the remote sampling of exhaled breath in Nalophan® bags prior to measurement using SESI-HRMS. To further explore the range of applications of this method, we conducted a proof-of-concept study to assess the impact of the storage time of exhaled breath in Nalophan® bags at different temperatures (room temperature and dry ice) on the relative intensities of the compounds. In addition, we performed a detailed study of the storage effect of 27 aldehydes related to oxidative stress. After 2 h of storage, the mean of intensity of allm/zsignals relative to the samples analyzed without prior storage remained above 80% at both room temperature and dry ice. For the 27 aldehydes, the mean relative intensity losses were lower than 20% at 24 h of storage, remaining practically stable since the first hour of storage following sample collection. Furthermore, the mean relative intensity of most aldehydes in samples stored at room temperature was higher than those stored in dry ice, which could be related to water vapor condensation issues. These findings indicate that the exhaled breath samples could be preserved for hours with a low percentage of mean relative intensity loss, thereby allowing more flexibility in the logistics of off-line SESI-HRMS studies.

Equilibrium vitrification of oocytes using low concentrations of cryoprotectants

In order to make dry ice transportation of vitrified embryos practical, a near-equilibrium vitrification was developed using a cryoprotectant solution (EDFS10/10a), by which mouse embryos at various stages were vitrified in a near-equilibrium environment. EDFS10/10a consisted of 10% (v/v) ethylene glycol, 10% (v/v) Me2SO, 0.4 M sucrose and 24% (w/v) Ficoll PM70. This method exhibited the benefits of slow freezing and vitrification, with a low risk of osmotic injury. In this study, we investigated whether mouse oocytes are vitrifiable with EDFS10/10a in a highly dehydrated/concentrated state, and whether they can remain fertilizable and developing into embryos after vitrification. When mature mouse oocytes were vitrified in liquid nitrogen and after 4-28 days of storage at -80 °C, high survival rates were observed (88-99%). Vitrified and warmed oocytes were subjected to partial zona dissection and in vitro fertilized. The rate of 2-cell stage was 80-82%. Blastocyst formation rate was 55-70% which was similar to that of embryos derived from fresh oocytes. After the 2-cell embryos were transferred to recipient mice, the implantation and offspring rates did not differ significantly from those of embryos derived from fresh oocytes, indicating that vitrified oocytes retained the developmental ability. Therefore, it is possible to vitrify mouse oocytes in a near-equilibrium state using EDFS10/10a and conveniently transported using dry ice.

A practical approach to the sampling, fixation, softening, and sectioning of whole honey bees for histologic evaluation

The Western honey bee (Apis mellifera) is economically important as the primary managed pollinator of many agricultural crops and for the production of various hive-related commodities. Honey bees are not classically or thoroughly covered in veterinary pathology training programs. Given their unique anatomic and biological differences from the other species more traditionally evaluated by veterinary pathologists, establishing routine and consistent methods for processing samples for histology ensures accurate diagnostic and research conclusions. We developed and tested several field protocols for the sampling of honey bees. We compared the tissue-quality outcomes for worker bees fixed, collected, and/or softened under the following protocols: 1) routine formalin fixation; 2) softening chitin via exposure to Nair for 2 d or 3) 5 d; 4) shortened times between formalin submersion and trimming of body segments to enhance penetration of formalin into internal tissues; 5) ethanol submersion of specimen prior to formalin fixation; 6) indirect dry ice exposure; and 7) prolonged -80°C storage. Routine formalin fixation, exposure to Nair for 2 d, indirect dry ice exposure, and trimming body segments within 2 h of formalin submersion resulted in the highest quality histologic tissue sections. The poorest quality sections resulted from softening of chitin by exposure to Nair for 5 d, submersion in ethanol for 3 d before formalin fixation, and prolonged storage at -80°C. Our results indicate that routine formalin fixation is adequate, and that immobilizing bees with indirect dry ice exposure aids in sample collection without negatively impacting the quality of histologic sections.

Shipping duration and temperature influence the characteristics of cryopreserved horse semen stored in different shipping devices for up to 14 days

This study aimed to investigate the effects of storing horse semen either in a dry shipper (≤ -150 °C) or on dry ice (≤ -78 °C) for up to 14 days. A total of 264 frozen semen straws from male horses (n = 8) stored in liquid nitrogen were transferred on day 0 (d0) to a dry shipper or a dry ice styrofoam box. On d1, d3, d7, d10, and d14, straws from the dry shipper and dry ice were returned to the liquid nitrogen container. Semen was evaluated by CASA for total (TMot), progressive motility (PMot) and sperm velocity parameters, by fluorescence microscopy for percentage of membrane-intact sperm (SYBR14/PI), high mitochondrial membrane potential (HMMP; JC1) and DNA fragmentation. Temperature inside the containers was monitored continuously. Until d7, no changes were observed in TMot, PMot, and membrane-intact spermatozoa. Thereafter, all three parameters decreased in semen stored on dry ice but not in a dry shipper (time p < 0.001, time x shipping device p < 0.001). The HMMP decreased continuously over time in both containers with a more pronounced decrease on dry ice compared to the dry shipper (shipping device p < 0.01, time p < 0.001, time x device p < 0.001). The DNA fragmentation increased on d10-14 on dry ice and d14 in the dry shipper (time p < 0.001, time x device p < 0.01). In conclusion, frozen horse semen can be safely stored for up to 7 days on dry ice. Sperm DNA integrity and HMMP, however, were adversely affected after 14 days in both shipping devices.

The effect of pre-treatment and anaerobic digestion for pathogens reduction in agricultural utilization of sewage sludge

The aim of the research work was to explain the possibilities of application of waste activated sludge (WAS) pretreatment processes prior to anaerobic digestion (mesophilic fermentation). Hydrodynamic disintegration and freezing/thawing disintegration methods were used. Based on the microbiological and parasitological analyses, a significant decrease in pathogenic bacteria, coliphages, and parasite eggs was observed. The number of bacteria analyzed (Salmonella sp., Escherichia coli, Clostridium perfringens) and coliphages were reduced from 19.3to 42.3% after hydrodynamic cavitation. A similar effect was achieved for destruction by freezing/thawing with dry ice between 7.8 and 14.9%. The effectiveness of parasite eggs reduction (Ascaris sp., Trichuris sp., Toxocara sp.) for these disintegration methods ranged from 10.7 to 29.3%. The highest results were observed for the hybrid disintegration method (hydrodynamic cavitation + dry ice disintegration) caused by a synergistic effect. Salmonella sp. in 1 g_d.w. decrease about 69.7%, E. coli by 70.0%, Clostridium perfringens by 38.4%, and coliphages by 48.2%. Disruption of WAS by a hybrid method led to a reduction in the number of helminth eggs Ascaris sp. (63.8%), Trichuris sp. (64.3%), and Toxocara sp. (66.4%). After anaerobic digestion under mesophilic conditions, an additional reduction of analyzed bacterial pathogens and helminth eggs were observed. The introduction of hybrid disintegrated WAS to the fermentation chamber resulted in higher efficiency in decrease (from 1 to 23%) in comparison to the control sample (70%WAS + 30%DS (inoculum-digested sludge)).

Development of a Simple Trap That Captures Ticks (Acari) on Their Dorsal Surface

We tested two versions of a trap that captures climbing ticks on their dorsum. A prototype based on a decades old model had three components, a truncated pyramidal base with steep sloping walls, downward facing sticky-tape extending beyond and spanning the boundary of the flat upper surface, on which ticks become dorsally immobilized, and a reservoir for gaseous CO2 emission from dry ice that rests on the flat upper surface. A preoperational trap was made of thermoformed plastic and differed from the prototype by its circular structure, a central depression suitable for future housing of a biotic CO2 generator and supplemental volatile lures and a transparent sticky ceiling that enables ticks to exhibit a phototactic response and allows users to see captured ticks without disturbing the traps. Field testing of the prototype in Florida and both trap types in Oklahoma and North Carolina achieved high catches of lone star ticks, Amblyomma americanum (L.) (Acari: Ixodidae), e.g. mean catches of >70 ticks (adults plus nymphs) in 4 h in both the prototype and preoperational traps in North Carolina, and significantly higher yields of ticks than on dry ice baited 1 m2 white sheets.

Development of a Simple Trap That Captures Ticks (Acari) on Their Dorsal Surface

We tested two versions of a trap that captures climbing ticks on their dorsum. A prototype based on a decades old model had three components, a truncated pyramidal base with steep sloping walls, downward facing sticky-tape extending beyond and spanning the boundary of the flat upper surface, on which ticks become dorsally immobilized, and a reservoir for gaseous CO2 emission from dry ice that rests on the flat upper surface. A preoperational trap was made of thermoformed plastic and differed from the prototype by its circular structure, a central depression suitable for future housing of a biotic CO2 generator and supplemental volatile lures and a transparent sticky ceiling that enables ticks to exhibit a phototactic response and allows users to see captured ticks without disturbing the traps. Field testing of the prototype in Florida and both trap types in Oklahoma and North Carolina achieved high catches of lone star ticks, Amblyomma americanum (L.) (Acari: Ixodidae), e.g. mean catches of >70 ticks (adults plus nymphs) in 4 h in both the prototype and preoperational traps in North Carolina, and significantly higher yields of ticks than on dry ice baited 1 m2 white sheets.

A comprehensive method to prevent top-coal spontaneous combustion utilizing dry ice as a fire extinguishing medium: test apparatus development and field application

There is a high potential for coal spontaneous combustion (CSC) above the roof beams of supports during the mining-stopped period. Early detection of temperature abnormal zones and corresponding measures are necessary to prevent CSC. In this work, a top-coal temperature measurement method was proposed, combining the coal surface temperature detection and the drilling temperature observation. Furthermore, an apparatus was developed that dramatically increases the rate of dry ice sublimation, resulting in the rapid release of cryogenic carbon dioxide gas. The device utilizes water from firefighting pipes in underground coal mines as a heat source for dry ice sublimation without electrical energy and has been applied and validated taking Silaogou Coal Mine in China as a field test site. Specifically, we found that during the stoppage period, the coal above the supports near the air inlet tunnel is more likely to appear hot spots; the carbon dioxide gas generated by the dry ice phase change device can quickly reduce the hot spots temperature, and the coal temperature does not rebound after the gas injection is stopped. Based on the above analysis, this work can effectively prevent the early top-coal spontaneous combustion during the stop mining period.

Dry ice in the eye: A rare occupational hazard!

Superficial corneal foreign bodies (FBs) are a common occupational ocular hazard and can cause visually important astigmatism. A 23-year-old male working in a factory, which produced dry ice (solid carbon dioxide), presented to our emergency unit with symptoms of whitish discolouration of the right cornea for 1 day. Visual acuity in both eyes was 20/20 and slit-lamp examination of the right eye revealed an irregularly shaped whitish superficial FB in the inferior paracentral cornea with surrounding superior nebular opacity. Its gentle removal with a moistened cotton bud revealed an underlying epithelial defect with residual whitish changes. At 1-month of follow-up, the patient had nebulo-macular corneal opacity with stromal thinning at the site of impacted dry ice. We speculate that dry ice causes corneal damage due to its extremely cold temperatures and the formation of carbonic acid.

Rapid cooling via dry ice preserves the genetic and morphological integrity of fish embryos

Larval fishes provide a valuable metric for assessing and monitoring species, populations, and ecosystem trends and condition. However, taxonomic resolution for this life stage is inherently problematic because of their individual sizes, limited morphological characteristics and high tissue degradation rates. There is little research on methods that rapidly preserve larval tissues for later morphological and molecular identification. The goal of this study was to test methods of rapidly killing fish embryos that maintain both morphological and molecular integrity. Rapid cooling with dry ice successfully maintained morphological and molecular integrity and may offer a simple and cost-effective approach for larval fish identification.

Waste-activated sludge disruption by dry ice: bench scale study and evaluation of heat phase transformations

The freezing process consists of dissipating heat from the product until the final temperature is lower than the temperature of crystallisation of that product. Freezing can be used for numerous applications, including for disruption of waste-activated sludge (WAS). The aim of this study was to calculate the estimated amount of heat conveyed between the solidified carbon dioxide and the WAS, in the following ratios: 0.25:1; 0.5:1; 0.75:1 and 1:1. In heat of phase transformations, dry ice sublimation, water solidification, the amount of heat transferred by other substances and heat transferred from the sludge (dry sludge) were taken into account during the process of WAS freezing. Heat changes on the surface of WAS were registered using a thermovision camera. The effectiveness of WAS disintegration was confirmed by several biochemical parameters such as soluble chemical oxygen demand (increase over 14 times), degree of disintegration (48%), proteins (increase over 5 times), carbohydrates (increase almost 7 times), RNA (increase by 2.23 mg L^-1), ammonia nitrogen (increase over 23 times), phosphates (increase almost 27 times) and turbidity (increased over 7 times). It was found that dry ice pretreatment of WAS can be an intriguing alternative for the conventional methods used.

Cryogenic Sample Processing with Liquid Nitrogen for Effective and Efficient Monitoring of Pesticide Residues in Foods and Feeds

With the monitoring of hundreds of pesticides in food and feed, the comminution step is equally crucial as any other to achieve valid results. However, sample processing is often underestimated in its importance and practical difficulty to produce consistent test portions for analysis. The scientific literature is rife with descriptions of microextraction methods, but ironically, sample comminution is often ignored or dismissed as being prosaic, despite it being the foundation upon which the viability of such techniques relies. Cryogenic sample processing using dry ice (-78 °C) is generally accepted in practice, but studies have not shown it to yield representative test portions of <1 g. Remarkably, liquid nitrogen has rarely been used as a cryogenic agent in pesticide residue analysis, presumably as a result of access, cost, and safety concerns. However, real-world implementation of blending unfrozen bulk food portions with liquid nitrogen (-196 °C) using common food processing devices has demonstrated this approach to be safe, simple, fast, and cost-effective and yield high-quality results for various commodities, including increased stability of labile or volatile analytes. For example, analysis of dithiocarbamates as carbon disulfide has shown a significant increase of thiram recoveries (up to 95%) using liquid nitrogen during sample comminution. This perspective is intended to allay concerns among working laboratories about the practical use of liquid nitrogen for improved sample processing in the routine monitoring of pesticide residues in foods and feeds, which also gives promise for feasible test sample size reduction in high-throughput miniaturized methods.

A Case Study of Cimex lectularius L. (Hemiptera: Cimicidae) Infestations in an Office Environment

Most field studies on Cimex lectularius are conducted in residential or hospitality industrial settings. Cimex lectularius infestations in office settings are reported, but are rarely studied. An office environment (~875 m2) consisting of 105 cubicles or pod-seating areas with persistent C. lectularius sightings over a 2-yr period was evaluated for 90 d through intensive trapping to determine C. lectularius distribution and to eliminate the infestation. The study area was partially occupied during the study period. Two treatments of amorphous silica dust (112.5 g dust in total) were applied 29 and 57 d after the first day of monitoring. A total of 32 C. lectularius were captured by interceptors over a period of 55 d. Dry ice traps captured eight additional C. lectularius. Visual inspections identified one chair with live C. lectularius and eggs. The infestation was eliminated on 69 d after initial installation of interceptors. Spatial analysis using Ripley's K and L functions showed a high level of aggregation up to a 15 meter scale. Dispersal of C. lectularius in office settings was limited. Intensive trapping plus limited insecticide dust treatments effectively detected and eliminated C. lectularius.

Effects of rosemary (Rosmarinus officinalis L.) extracts and dry ice on the physicochemical stability of omega-3 fatty-acid-fortified surimi-like meat products

BACKGROUND

Lipid peroxidation entails major quality degradation in omega-3 (ω-3) fatty-acid-fortified surimi-like meat products upon storage. Currently, the use of label-friendly alternatives to synthetic antioxidants is encouraged in the industry. Hence, we aimed to examine the applicability of the hurdle-technology concept, using an 80% (v/v) ethanol solution to obtain rosemary extracts (REs) containing substantial amounts of polyphenol, and dry ice (DI) which can create a cryogenic environment, on the physicochemical stabilities of ω-3 fatty-acid (FA)-fortified meat products after manufacturing and storage periods. The polyphenolic profiles of the REs were also investigated.

RESULTS

Carnosol and rosmarinic acid are major phenolic components in REs. Furthermore, DI addition during the chopping procedure increased (P < 0.05) whiteness values and hardness of products, while total ω-3 and ω-6 FAs were relatively well preserved (P < 0.05) in products with flaxseed oil premixed with RE. During 14-day storage at 4 °C, combined treatment with RE and DI decreased (P < 0.05) thiobarbituric acid reactive substance (TBARS) levels and the centrifugation loss of products. Single or combined treatment with RE and/or DI decreased (P < 0.05) TBARS levels in products after 60 days of storage at -20 °C.

CONCLUSION

Due to the antioxidant-polyphenol profile of REs and a possible oxygen exclusion of DI treatment under atmospheric pressure during food manufacturing, application of the hurdle-technology concept, using treatment with both RE and DI, can reduce lipid peroxidation and maintain a greater water-holding capacity of ω-3 FA-fortified meat products upon storage. © 2019 Society of Chemical Industry.

Borrelia parkeri in Ornithodoros parkeri (Ixodida: Argasidae) Collected Using Compact Dry Ice Traps in Madera County, California

Tick-borne relapsing fever (TBRF) is a potentially serious vector-borne disease endemic to the western United States. Vector surveillance is compromised by the nidicolous life history of the three Ornithodoros species that transmit TBRF to people in this region. Large-scale stationary trapping methods were developed to survey a wide geographical range of Ornithodoros spp. which are known to vector relapsing fever Borrelia spp. in California. Ninety-six Ornithodoros parkeri were collected from four locations in the foothills of Fresno and Madera Counties. Two of these O. parkeri nymphs were PCR positive for Borrelia parkeri, and their collection at a popular recreation site increases the public health concern.

A Comparative Study of Mosquito and Sand Fly (Diptera: Psychodidae: Phlebotominae) Sampling Using Dry Ice and Chemically Generated Carbon Dioxide From Three Different Prototype CO2 Generators

A comparative study was conducted to test the efficiency of Centers for Disease Control and Prevention (CDC) light traps baited with either dry ice or carbon dioxide (CO2) produced from one of three different sources in collecting mosquitoes (Diptera: Culicidae) in Thailand. Treatments consisted of dry ice pellets, CO2 gas produced from one of three prototype CO2 generator systems (TDA, CUBE, Moustiq-Air Med-e-Cell - MEC), and a CDC light trap without a CO2 source. The best performing prototype from Thailand was then tested in collecting sand flies (Diptera: Psychodidae: Phlebotominae) in Greece. A total of 12,798 mosquitoes and 8,329 sand flies were sampled during the experimentation. The most prevalent mosquito species collected in Thailand were: Culex vishnui Theobald > Anopheles minimus Theobald > Culex tritaeniorhynchus Giles > Anopheles sawadwongporni Rattanarithikul & Green. By far the most prevalent sand fly species collected in Thessaloniki was Phlebotomus perfiliewi Parrot followed by Phlebotomus tobbi Adler and Theodor and Phlebotomus simici Nitzulescu. In general, the TDA treatment was the only treatment with no significant difference from the dry ice-treatment in mean trap catches. Although dry ice-baited traps caught higher numbers of mosquitoes and sand flies than the TDA-baited traps, there was no difference in the number of species collected. Results indicate that the traps baited with the TDA CO2 generator were as attractive as traps supplied with dry ice and, therefore, the TDA CO2 generator is a suitable alternative to dry ice as a source of carbon dioxide for use with adult mosquito and sand fly traps.

DEVELOPMENT OF THE CHARCOAL ADSORPTION TECHNIQUE FOR DETERMINATION OF RADON CONTENT IN NATURAL GAS

A technique for the determination of the radon concentration in natural gas using charcoal adsorption has been developed to study the effects of parameters that influence the adsorption efficiency of radon onto activated charcoal. Several sets of experiments were conducted both in the laboratory and in an actual natural gas field for comparison. The results show that the adsorption capability of radon onto activated charcoal varies inversely with temperature, hydrocarbon concentration and the humidity contained within the natural gas. A technique utilizing dry ice as a coolant was found to be the most effective for trapping radon in natural gas samples at the production site. A desiccant can be used to remove moisture from the sampling gas. The technique described here increases the adsorption efficiency of activated charcoal by 10-20% compared to our previous study.

Experimental determination of surface heat transfer coefficient in a dry ice-ethanol cooling bath using a numerical approach

BACKGROUND: Dry ice-ethanol bath (-78 degree C) have been widely used in low temperature biological research to attain rapid cooling of samples below freezing temperature. The prediction of cooling rates of biological samples immersed in dry ice-ethanol bath is of practical interest in cryopreservation. The cooling rate can be obtained using mathematical models representing the heat conduction equation in transient state. Additionally, at the solid cryogenic-fluid interface, the knowledge of the surface heat transfer coefficient (h) is necessary for the convective boundary condition in order to correctly establish the mathematical problem.

OBJECTIVE

The study was to apply numerical modeling to obtain the surface heat transfer coefficient of a dry ice-ethanol bath.

MATERIALS AND METHODS

A numerical finite element solution of heat conduction equation was used to obtain surface heat transfer coefficients from measured temperatures at the center of polytetrafluoroethylene and polymethylmetacrylate cylinders immersed in a dry ice-ethanol cooling bath. The numerical model considered the temperature dependence of thermophysical properties of plastic materials used.

RESULTS

A negative linear relationship is observed between cylinder diameter and heat transfer coefficient in the liquid bath, the calculated h values were 308, 135 and 62.5 W/(m²K) for PMMA 1.3, PTFE 2.59 and 3.14 cm in diameter, respectively.

CONCLUSION

The calculated heat transfer coefficients were consistent among several replicates; h in dry ice-ethanol showed an inverse relationship with cylinder diameter.

Cryoinjury Model for Tissue Injury and Repair in Bioengineered Human Striated Muscle

Regenerative medicine aims to replace injured tissues to restore normal physiological function. One possibility for achieving this goal is to activate or enhance endogenous regenerative pathways. Therefore, human tissue regeneration models may be useful tools for the discovery and development of novel regenerative therapeutics. In this chapter, we describe methods for the generation of three-dimensional bioengineered striated muscle in vitro and a cryoinjury model that can be applied to these tissues. This technique enables mechanistic in vitro analysis of the endogenous regenerative response of human striated muscle to injury, which is not possible using other in vivo approaches.

Application of biogenic carbon dioxide produced by yeast with different carbon sources for attraction of mosquitoes towards adult mosquito traps

Surveillance is a prime requisite for controlling arthropod vectors like mosquitoes that transmit diseases such as malaria, dengue and chikungunya. Carbon dioxide (CO2) is one of the main cues from vertebrate breath that attracts mosquitoes towards the host. Hence, CO2 is used as an attractant during surveillance of mosquitoes either from commercial cylinders or dry ice for mosquito traps. In the present study, the biogenic carbon dioxide production was optimized with different carbon sources such as glucose, simple sugar and jaggery with and without yeast peptone dextrose (YPD) media using commercial baker's yeast. The results showed that yeast produced more biogenic CO2 with simple sugar as compared to other carbon sources. Further substrate concentration was optimized for the continuous production of biogenic CO2 for a minimum of 12 h by using 10 g of baker's yeast with 50 g of simple sugar added to 1.5 l distilled water (without YPD media) in a 2-l plastic bottle. This setup was applied in field condition along with two different mosquito traps namely Mosquito Killing System (MKS) and Biogents Sentinel (BGS) trap. Biogenic CO2 from this setup has increased the trapping efficiency of MKS by 6.48-fold for Culex quinquefasciatus, 2.62-fold for Aedes albopictus and 1.5-fold for Anopheles stephensi. In the case of BGS, the efficiency was found to be increased by 3.54-fold for Ae. albopictus, 4.33-fold for An. stephensi and 1.3-fold for Armigeres subalbatus mosquitoes. On the whole, plastic bottle setup releasing biogenic CO2 from sugar and yeast has increased the efficiency of MKS traps by 6.38-fold and 2.74-fold for BGS traps as compared to traps without biogenic CO2. The present study reveals that, among different carbon sources used, simple sugar as a substance (which is economical and readily available across the world) yielded maximum biogenic CO2 with yeast. This setup can be used as an alternative to CO2 cylinder and dry ice in any adult mosquito traps to enhance their trapping efficiency of a mosquito surveillance programme.

A Comparison of Carbon Dioxide Sources for Mosquito Capture in Centers for Disease Control and Prevention Light Traps on the Florida Gulf Coast (1)

Traditional sources of carbon dioxide (CO₂), dry ice, and compressed gas, were tested against 3 combinations of food-grade reagents known to generate CO₂using a compact, lightweight generator delivery system with Centers for Disease Control and Prevention light traps. Three 6 × 6 Latin square trials were completed near the Florida Gulf Coast in the Lower Suwannee Wildlife Refuge during the summer of 2013, collecting a total of 31,632 female mosquitoes. Treatments included dry ice, compressed CO₂gas, a control trap (no CO₂), citric acid + sodium bicarbonate, vinegar + sodium bicarbonate, and yeast + sugar. Decreasing order of trap collections (treatment mean number of mosquitoes per trap night ± standard error) were dry ice 773.5 (± 110.1) > compressed gas 440.7 (± 42.3) > citric acid + sodium bicarbonate 197.6 (± 30.4), yeast + sugar 153.6 (± 27.4) > vinegar + sodium bicarbonate 109.6 (± 16.2) > control 82.4 (± 14.0). A 2-way Kruskal-Wallis analysis by treatment, site, and treatment × site interaction identified significant differences between all treatments. Although dry ice and compressed CO₂gas collected significantly more mosquitoes than other combinations (P < 0.05), use of citric acid and sodium bicarbonate or yeast and sugar greatly outperformed unbaited traps and offer a good alternative to dry ice and compressed gas in areas where these agents are not readily available or are difficult to obtain due to logistical constraints. An inexpensive, portable CO₂generator for use with food-grade reagents is described.

TEMPORARY STORAGE OF BOVINE SEMEN CRYOPRESERVED IN LIQUID NITROGEN ON DRY ICE AND REFREEZING OF FROZEN-THAWED SEMEN

Two experiments were conducted. The purpose of Experiment 1 was to investigate whether viability of bovine semen stored in liquid nitrogen (-196°C) will be adversely affected by temporary exposure to dry ice (-79°C). It was convincingly shown that post thaw-motility was not affected, regardless whether semen was thawed immediately or after being returned to liquid nitrogen. Shipping or temporary storage on dry ice, thus, is a viable option. In Experiment 2, refreezing of frozen-thawed semen was attempted. The proportion of motile spermatozoa was reduced by a factor of ten to between 6.0 % and 7.4 %, regardless whether thawing occurred directly after removal from liquid nitrogen or after an interim period on dry ice. When semen was refrozen on dry ice before being returned to liquid nitrogen, motility rates were significantly improved (13.0 % to 17.0 %, P<0.05). In both experiments sperm cells that remained motile displayed vigorous forward movement and normal morphological appearance.

Effectiveness of a Sugar-Yeast Monitor and a Chemical Lure for Detecting Bed Bugs

Effective bed bug (Cimex lectularius L.) monitors have been actively sought in the past few years to help detect bed bugs and measure the effectiveness of treatments. Most of the available active monitors are either expensive or ineffective. We designed a simple and affordable active bed bug monitor that uses sugar-yeast fermentation and an experimental chemical lure to detect bed bugs. The sugar-yeast mixture released carbon dioxide at a similar rate (average 405.1 ml/min) as dry ice (average 397.0 ml/min) during the first 8 h after activation. In naturally infested apartments, the sugar-yeast monitor containing an experimental chemical lure (nonanal, L-lactic acid, 1-octen-3-ol, and spearmint oil) was equally effective as the dry ice monitor containing the same lure in trapping bed bugs. Placing one sugar-yeast monitor per apartment for 1-d was equally effective as 11-d placement of 6-18 Climbup insect interceptors (a commonly used bed bug monitor) under furniture legs for trapping bed bugs. When carbon dioxide was present, pair-wise comparisons showed the experimental lure increased trap catch by 7.2 times. This sugar-yeast monitor with a chemical lure is an affordable and effective tool for monitoring bed bugs. This monitor is especially useful for monitoring bed bugs where a human host is not present.

Variation in Baiting Intensity Among CO2-Baited Traps Used to Collect Hematophagous Arthropods

Hematophagous arthropods transmit the etiological agents of numerous diseases and as a result are frequently the targets of sampling to characterize vector and pathogen populations. Arguably, the most commonly used sampling approach involves traps baited with carbon dioxide. We report results of a laboratory study in which the performance of carbon dioxide-baited traps was evaluated using measures of baiting intensity, the amount of carbon dioxide released per unit time during trap deployment. We evaluated the effects of trap design, carbon dioxide source, and wind speed on baiting intensity and documented significant effects of these factors on the length of sampling (time to baiting intensity = 0), maximum baiting intensity, and variation in baiting intensity during experimental trials. Among the three dry ice-baited trap types evaluated, traps utilizing insulated beverage coolers as dry ice containers sampled for the longest period of time, had the lowest maximum but most consistent baiting intensity within trials and were least sensitive to effects of wind speed and dry ice form (block vs. pellet) on baiting intensity. Results of trials involving traps baited with carbon dioxide released from pressurized cylinders suggested that this trap type had performance comparable to dry ice-baited insulated cooler traps but at considerably higher cost.

Effects of euthanasia method on stable-carbon and stable-nitrogen isotope analysis for an ectothermic vertebrate

RATIONALE

Stable isotope analysis is a critical tool for understanding ecological food webs; however, results can be sensitive to sample preparation methods. To limit the possibility of sample contamination, freezing is commonly used to euthanize invertebrates and preserve non-lethal samples from vertebrates. For destructive sampling of vertebrates, more humane euthanasia methods are preferred to freezing and it is essential to evaluate how these euthanasia methods affect stable isotope results.

METHODS

Stable isotope ratios and elemental composition of carbon and nitrogen were used to evaluate whether the euthanasia method compromised the integrity of the sample for analysis. Specifically, the stable isotope and C:N ratios were compared for larval wood frogs (Rana sylvatica  =  Lithobates sylvaticus), an ectothermic vertebrate, that had been euthanized by freezing with four different humane euthanasia methods: CO2, benzocaine, MS-222 (tricaine methanesulfonate), and 70% ethanol.

RESULTS

The euthanasia method was not related to the δ(13)C or δ(15)N values and the comparisons revealed no differences between freezing and any of the other treatments. However, there were slight (non-significant) differences in the isotope ratios of benzocaine and CO2 when each was compared with freezing. The elemental composition was altered by the euthanasia method employed. The percentage nitrogen was higher in CO2 treatments than in freezing, and similar (non-significant) trends were seen for ethanol treatments relative to freezing. The resulting C:N ratios were higher for benzocaine treatments than for both CO2 and ethanol. Similar (non-significant) trends suggested that the C:N ratios were also higher for animals euthanized by freezing than for both CO2 and ethanol euthanasia methods.

CONCLUSIONS

The euthanasia method had a larger effect on elemental composition than stable isotope ratios. The percentage nitrogen and the subsequent C:N ratios were most affected by the CO2 and ethanol euthanasia methods, whereas non-significant trends suggested that benzocaine and CO2 altered the stable isotope ratios. It appears that the use of MS-222 and freezing with dry ice are the most appropriate euthanasia methods for ectothermic vertebrates.

High osmolality vitrification: a new method for the simple and temperature-permissive cryopreservation of mouse embryos

Procedures for cryopreserving embryos vary considerably, each having its specific advantages and disadvantages in terms of technical feasibility, embryo survival yield, temperature permissibility and species- or strain-dependent applicability. Here we report a high osmolality vitrification (HOV) method that is advantageous in these respects. Cryopreservation by vitrification is generally very simple, but, unlike slow freezing, embryos should be kept at a supercooling temperature (below –130°C) to avoid cryodamage. We overcame this problem by using an HOV solution containing 42.5% (v/v) ethylene glycol, 17.3% (w/v) Ficoll and 1.0 M sucrose. This solution is more viscous than other cryopreservation solutions, but easy handling of embryos was assured by employing a less viscous equilibration solution before vitrification. Most (>80%) embryos cryopreserved in this solution survived at –80°C for at least 30 days. Normal mice were recovered even after intercontinental transportation in a conventional dry-ice package for 2–3 days, indicating that special containers such as dry shippers with liquid nitrogen vapor are unnecessary. The HOV solution could also be employed for long-term storage in liquid nitrogen, as with other conventional cryoprotectants. Finally, we confirmed that this new vitrification method could be applied successfully to embryos of all six strains of mice we have tested so far. Thus, our HOV method provides an efficient and reliable strategy for the routine cryopreservation of mouse embryos in animal facilities and biomedical laboratories, and for easy and cheap transportation.

Pigeon louse fly, Pseudolynchia canariensis (Diptera: Hippoboscidae), collected by dry-ice trap

During a mosquito collection, a female of the pigeon louse fly, Pseudolynchia canariensis (Diptera: Hippoboscidae), was collected by a mosquito trap baited with dry ice in Ishigaki-jima, Yaeyama Islands, Japan. This is the 1st record of P. canariensis from Yaeyama Islands.

Efficacy of dry ice-baited traps for sampling Amblyomma americanum (Acari: Ixodidae) varies with life stage but not habitat

The carbon dioxide-baited trap is the most common and effective method for sampling vector life-stage Amblyomma americanum (L.) (Acari: Ixodidae), although confounding environmental variables are rarely considered. A mark-recapture experiment was designed to compare recapture proportions of A. americanum nymphs and adults between two habitat types: old field and oak-hickory forest. Powdered fluorescent dye was used to mark A. americanum ticks released in 1-m increments from carbon dioxide-baited traps. Adults were recaptured in significantly higher proportion than nymphs, but habitat type had no significant effect on recapture proportions. Tick abundance is an important parameter in the estimation of human risk of exposure to tick-borne disease and the influence of life stage on capture rates should be considered when calculating entomological risk.

Bloodmeal host congregation and landscape structure impact the estimation of female mosquito (Diptera: Culicidae) abundance using dry ice-baited traps

Vegetation patterns and the presence of large numbers of nesting herons and egrets significantly altered the number of host-seeking Culex tarsalis Coquillett (Diptera: Culicidae) collected at dry ice-baited traps. The numbers of females collected per trap night at traps along the ecotone of Eucalyptus stands with and without a heron colony were always greater or equal to numbers collected at traps within or under canopy. No Cx. tarsalis were collected within or under Eucaplytus canopy during the peak heron nesting season, even though these birds frequently were infected with West Nile virus and large number of engorged females could be collected at resting boxes. These data indicate a diversion of host-seeking females from traps to nesting birds reducing sampling efficiency.

Simple and inexpensive method for cryopreservation of fish sperm combining straw and powdered dry ice

Here, we propose a simple and inexpensive method for fish sperm cryopreservation. Sperm samples of the loach Misgurnus anguillicaudatus (Teleostei: Cobitidae) were diluted 7-fold by an extender containing 63.5 mM NaCl, 114 mM KCl, 20 mM Tris and 10% methanol. The cryogenic straws were placed in three kinds of self-made tubes which diameter was changed by commercially available materials and then immersed into powdered dry ice for 2 min and plunged into liquid nitrogen. This procedure resulted in a cooling rate at -421.4 +/- 119.84 (control), -55.8 +/- 4.32 (tube 1), -40.2 +/- 3.43 (tube 2) and -33.3 +/- 2.09 C/min (tube 3). In the slowest cooling rate by the tube 3, total motility (72 +/- 3 %), duration (146 +/- 12 s) and hatching rates (29 +/- 04 %) were higher than those by other rates. Progressive motility (83 +/- 5 %) did not differ significantly from fresh samples.

Evaluation of two current approaches for the measurement of carbon dioxide diffusive fluxes from lentic ecosystems

The dry ice sowing experiment (DISE) consisted in adding dry ice to a lake and monitoring the subsequent evasion of carbon dioxide (CO2). DISE allowed us to evaluate two approaches commonly used for measuring aquatic CO2 diffusive fluxes: the boundary layer equation (BLE) from Cole and Caraco (1998) and a particular model of static chamber (SC). CO2 evasion measurements with both approaches were compared to CO2 mass budgets as a relative reference to define their recovery coefficients (p). p for the BLE and the SC over the whole measurement period were 101 +/- 14% and 115 +/- 56%, respectively. Results from discrete sampling intervals revealed that the BLE generally provided estimations in good agreement (80-130%) with the mass budgets during both daytime and nighttime. Variations in p for the BLE were related to wind speed and, consequently, piston velocity (k600). The SC overestimated CO2 evasion during daytime (149 +/- 39%), and underestimated it during nighttime (57 +/- 18%). Variations in p for the SC were related to k600, stemming mainly from the alteration of the air/ water temperature gradient.

Maintaining a frozen shipping environment for Phase I clinical trial distribution

The need for stringent temperature control provides significant challenges to pharmaceutical distributors operating in all sectors of the industry. Products with a frozen storage label requirement can be significantly problematic. This study aimed to provide evidence of robust and reproducible frozen shipment arrangements to be operated by a Phase I clinical trial unit. Dry ice was used to achieve a deep frozen internal parcel environment and was tested in a laboratory setting using ultra low temperature loggers within dummy product packs within the test parcels. The laboratory dry ice packing configuration was then repeatedly tested in real time transits using a Glasgow to London delivery schedule. An internal temperature specification was set to not exceed -10 degrees C during the transport. During each delivery, external temperature monitoring measured the temperature stress experienced by the box in transit. Results demonstrated the ability of the chosen system to not exceed -13.6 degrees C on average (-10 degrees C maximum) when exposed to external temperatures of up to +20.1 degrees C (mean kinetic temperature). The effect was maintained for at least 52.5h.

The detection of carbonation by the Drosophila gustatory system

There are five known taste modalities in humans: sweet, bitter, sour, salty and umami (the taste of monosodium glutamate). Although the fruitfly Drosophila melanogaster tastes sugars, salts and noxious chemicals, the nature and number of taste modalities in this organism is not clear. Previous studies have identified one taste cell population marked by the gustatory receptor gene Gr5a that detects sugars, and a second population marked by Gr66a that detects bitter compounds. Here we identify a novel taste modality in this insect: the taste of carbonated water. We use a combination of anatomical, calcium imaging and behavioural approaches to identify a population of taste neurons that detects CO2 and mediates taste acceptance behaviour. The taste of carbonation may allow Drosophila to detect and obtain nutrients from growing microorganisms. Whereas CO2 detection by the olfactory system mediates avoidance, CO2 detection by the gustatory system mediates acceptance behaviour, demonstrating that the context of CO2 determines appropriate behaviour. This work opens up the possibility that the taste of carbonation may also exist in other organisms.

Estimation of aerosol droplet sizes by using a modified DC-III portable droplet measurement system under laboratory and field conditions

Modification of the DC-III portable droplet measurement system, permitting its use under field conditions, is described. Under laboratory conditions, the system effectively sampled water droplets from aerosols produced by a dry ice/water generator and high-pressure syringe. Seven droplet sizes, totaling 71,053 droplets within 22 tests (dry ice method), consisted of 1-, 2-, 6-, 11-, 18-, 25-, and 34-microm droplets with individual (rounded) percentages of 45.25, 37.22, 13.85, 3.17, 0.45, 0.02, and 0.005, respectively, for each size. Cumulatively, 1-microm droplets accounted for ca. 45.25% of the droplets sampled; combined with 2-microm (ca. 82.48% together), 6-microm (ca. 96.33% together), and 11-microm droplets, yielded ca. 99.51% of the droplets sampled. The syringe produced 12 droplet sizes, with 4,121 droplets sampled, consisting of 1, 2, 6, 11, 18, 25, 34, 45, 56, 69, 83, and 99 microm with individual percentages of 15.43, 21.91, 24.58, 17.30, 10.62, 4.65, 2.93, 1.33, 0.63, 0.33, 0.16, 0.07, respectively, for each size. The 6-microm droplets contributed the highest individual percentage, and cumulatively, these droplets combined with 1- and 2-microm droplets, yielding 61.93%, whereas 11- to 45-microm droplets contributed 36.83%, for a total of 98.76%. Droplets measuring 56-99 microm accounted for ca. 1.24% of droplets sampled. Hand-fogger oil aerosols produced 12 droplet sizes (1-38 microm) at test distances of 7.6 and 15.2 m, with 1,979 and 268 droplets sampled, respectively, during 10 tests at each distance. With analysis of variance of transformed individual percentages for each size at both distances, no significant differences were observed for 7.6 and 15.2 m. Cumulatively, 1-, 2-, 3-, and 5-microm droplets contributed 82.87 and 80.97%, whereas 8-, 11-, 14-, and 18-microm droplets added 14.55% to totals at both 7.6 and 15.2 m, respectively. Droplets measuring 22, 27, 32, and 38 microm contributed 2.57% and 4.47% to samples obtained at 7.6 and 15.2 m. The average mass median diameter (MMD) of mineral oil aerosols obtained at 7.6 and 15.2 m were 19.55 +/- 1.62 and 15.49 +/- 1.35, respectively. Positioned at 15 m (50 ft) within a field cage test plot during 12 separate tests, the MMD values obtained downrange were less than calibration MMD values in 5 tests (10-93% of calibration values), but 1.1 to 4.4 times greater in 7 remaining tests. With exception of 2 tests, susceptible Sebring strain Culex quinquefasciatus mortality at the 31-m (100-ft) stake, 15 m (50 ft) behind the DC-III, was consistently 100%. The average MMD values for malathion, permethrin, and resmethrin (at 0.003 and 0.007 rates) at this distance were 13.24 +/- 6.08, 7.48 +/- 5.69, 16.64 +/- 5.54, and 15.48 +/- 2.89, respectively.

Quantitative and qualitative studies on the bacteriological quality of Indian white shrimp (Penaeus indicus) stored in dry ice

Indian white shrimp (Penaeus indicus) stored in dry ice at the 1:1 ratio were found to be organoleptically suitable for consumption when they were stored for 24 h without reicing. Shrimp stored in water ice at the 1:1 ratio (as control) were acceptable up to 18 h. Shrimp stored in a combination of dry ice and water ice at the ratio of 1:0.2:0.5 were also found to be acceptable up to 24 h. Total bacterial load ranged from 10(6) to 10(9) cfu g(-1), while total psychrophiles ranged from 10(3) to 10(6) cfu g(-1). Total lactics were found in the levels of 10(2)-10(6) cfu g(-1). H(2)S producers were from 10(3) to 10(5) cfu g(-1). Lowest temperature of -4.8 degrees C was observed in shrimps stored in dry ice at 1:1 ratio. Bacterial flora associated with fresh raw shrimp were Aeromonas, Pseudomonas, Vibrio, Flavobacterium and Serratia. Aeromonas constituted 38% of the flora in raw shrimp. Flavobacterium (43%), Pseudomonas (47%) and Pseudomonas (38%) were the dominant bacterial flora in the shrimp stored in dry ice at 1:1 ratio, in the combination package, and in water ice at 1:1 ratio, respectively.

Cryopreservation of spermatozoa of black marlin, Makaira indica (Teleostei: Istiophoridae)

As a first step towards the development of a method for the cryopreservation of black marlin spermatozoa, this study investigated the effect of dimethylsulfoxide (DMSO) concentration and pellet size on post-thaw spermatozoal motility. Spermatozoa were recovered from the spermatic duct of testes retrieved post-mortem from four adult black marlin caught in the Coral Sea spawning grounds of Australia. Undiluted spermatozoa were stored on ice for 4 to 10 hours during transport to shore, then evaluated for motility after activation in seawater (1:10 v:v). Spermatozoa were prepared for cryopreservation in pellets by extension (1:3 v:v) in a defined fish Ringer's solution to give two final DMSO concentrations of 2.5% or 5.0%. Diluted spermatozoa were frozen directly on a dry ice block in pellet sizes of either 0.25 ml or 0.50 ml. Frozen pellets were thawed in a water bath at 40 degrees C for 60 seconds and assessed for post-thaw motility following activation in seawater. Spermatozoa recovered within 50 minutes of death and chilled on ice for 4 to 10 hours showed a mean (+/- SEM) motility immediately following activation of 91.6 +/- 7.9%. 50% of the spermatozoa remained motile for approximately 4 to 5 minutes. Following cryopreservation, mean motility declined significantly across all cryoprotectant and pellet size combinations (P < 0.001) but spermatozoa frozen in 2.5% DMSO showed higher motility than those frozen in 5.0% DMSO (P = 0.014). Pellet size had no effect on post-thaw motility (P = 0.179).

Performance of a prototype baited-trap in attracting and infecting the tick Amblyomma variegatum (Acari: Ixodidae) in field experiments

Investigations were commenced to study the potential use of the fungi, Beauveria bassiana, Metarhizium anisopliae, and the attraction-aggregation-attachment pheromone (AAAP) for the control of Ambloyomma variegatum as an environmentally friendly technology. The objective of the study was to develop and test a device, which could be used for pheromone and carbon dioxide delivery and infection of ticks with the fungi in an attempt to control the tick populations in the vegetation. Using a pheromone-baited device treated with the fungi mixture, 79% of the ticks released were attracted and exposed to the fungi and of these, 78% died during incubation in the laboratory. In another set of experiments, of the released ticks that were similarly exposed to fungi using the pheromone-baited device and left in the vegetation, 33.8% were recovered compared to recoveries of between 76 and 84% in the controls. These results were significantly different at the 5% level, an indication that the pheromone/fungi mixtures had significant effect in reducing the tick population in the field.

A comparative study of adult mosquito trapping using dry ice and yeast generated carbon dioxide

Adult mosquito collections were conducted for 12 weeks in two residential areas in Kuala Lumpur. The CDC light traps were compared using dry ice and yeast as sources of carbon dioxide attractants for mosquitoes. The efficacy of the dry ice baited trap was significant over yeast generated CO2 trap. The predominant species obtained were Culex quinquefasciatus, Stegomyia albopicta and Armigeres subalbatus.

A 5-micron-bright spot on Titan: evidence for surface diversity

Observations from the Cassini Visual and Infrared Mapping Spectrometer show an anomalously bright spot on Titan located at 80 degrees W and 20 degrees S. This area is bright in reflected light at all observed wavelengths, but is most noticeable at 5 microns. The spot is associated with a surface albedo feature identified in images taken by the Cassini Imaging Science Subsystem. We discuss various hypotheses about the source of the spot, reaching the conclusion that the spot is probably due to variation in surface composition, perhaps associated with recent geophysical phenomena.

[Growth inhibition of Vibrio parahaemolyticus in seafood by tabletop dry ice cooler]

Tabletop dry ice coolers (three types; dome model, cap model and tripod model), which are used in kitchens and hotel banquet halls to refrigerate fresh seafood, were investigated to determine whether growth of Vibrio parahaemolyticus was inhibited by their use. On TSA plates containing 1.8% NaCl and fresh seafood (fillets of squid, pink shrimp and yellowtail), V. parahaemolyticus (O3:K6, TDH+) inoculated at 4 to 5 log CFU/sample and left at ambient temperature (25 degrees C) grew by 1.0 to 2.8 orders in 4 hours. In contrast, with tabletop coolers no significant increase in viable count occurred in 3 to 4 hours, confirming that tabletop coolers inhibited the growth of V. parahaemolyticus. The temperature in each tabletop cooler was kept below 10 degrees C for 80 to 135 min, though the CO2 gas concentration in them remained high for only a short time (0 to 75 min). It was presumed that the refrigeration function mainly contributed to growth inhibition. Our results indicate that tabletop dry ice coolers are helpful for prevention of food-borne disease due to V. parahaemolyticus in food-service locations, such as kitchens and banquet halls.

Production of oxidants by ion irradiation of water/carbon dioxide frozen mixtures

We present new experimental results on the formation of oxidants, such as hydrogen peroxide, ozone, and carbonic acid, under ion irradiation of icy mixtures of water/carbon dioxide at different ratios and temperatures (16 and 80 K). Pure water ice layers and mixtures with carbon dioxide were irradiated by 200 keV He+ ions. We found that the CO(2)/H(2)O ratio progressively decreased to a value of about 0.1, the H(2)O(2) production increased with increasing CO(2) abundance at both 16 and 80 K, and the CO and H(2)CO(3) production increased with increasing CO(2) abundance at 16 K. At 80 K, the synthesis of CO was less efficient because of the high volatility of the molecule that partially sublimed from the target. The production of carbonic acid was connected with the production of CO(3). O(3) was detected only after ion irradiation of CO(2)-rich mixtures. The experimental results are discussed with regard to the relevance they may have in the production of an energy source for a europan or a martian biosphere.

Mars Surface Diversity as Revealed by the OMEGA/Mars Express Observations

The Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) investigation, on board the European Space Agency Mars Express mission, is mapping the surface composition of Mars at a 0.3- to 5-kilometer resolution by means of visible-near-infrared hyperspectral reflectance imagery. The data acquired during the first 9 months of the mission already reveal a diverse and complex surface mineralogy, offering key insights into the evolution of Mars. OMEGA has identified and mapped mafic iron-bearing silicates of both the northern and southern crust, localized concentrations of hydrated phyllosilicates and sulfates but no carbonates, and ices and frosts with a water-ice composition of the north polar perennial cap, as for the south cap, covered by a thin carbon dioxide-ice veneer.