Tropical Weather Conditions Research Articles

The association between temperature and mortality in tropical middle income Thailand from 1999 to 2008

We have investigated the association between tropical weather condition and age-sex adjusted death rates (ADR) in Thailand over a 10-year period from 1999 to 2008. Population, mortality, weather and air pollution data were obtained from four national databases. Alternating multivariable fractional polynomial (MFP) regression and stepwise multivariable linear regression analysis were used to sequentially build models of the associations between temperature variable and deaths, adjusted for the effects and interactions of age, sex, weather (6 variables), and air pollution (10 variables). The associations are explored and compared among three seasons (cold, hot and wet months) and four weather zones of Thailand (the North, Northeast, Central, and South regions). We found statistically significant associations between temperature and mortality in Thailand. The maximum temperature is the most important variable in predicting mortality. Overall, the association is nonlinear U-shape and 31°C is the minimum-mortality temperature in Thailand. The death rates increase when maximum temperature increase with the highest rates in the North and Central during hot months. The final equation used in this study allowed estimation of the impact of a 4°C increase in temperature as projected for Thailand by 2100; this analysis revealed that the heat-related deaths will increase more than the cold-related deaths avoided in the hot and wet months, and overall the net increase in expected mortality by region ranges from 5 to 13% unless preventive measures were adopted. Overall, these results are useful for health impact assessment for the present situation and future public health implication of global climate change for tropical Thailand.

Influence of air quality on the composition of microbial pathogens in fresh rainwater.

In this study, the microbiological quality of fresh rainwater was assessed from 50 rain events under tropical weather conditions for a year. The levels of four major opportunistic waterborne pathogens, namely, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Aeromonas hydrophila, in rainwater samples were quantified by using a robust and sensitive quantitative PCR (qPCR) method. Of the 50 rainwater samples, 25 were found to be positive for at least one pathogen: 21 for E. coli, 16 for P. aeruginosa, 6 for K. pneumoniae, and 1 for A. hydrophila. In addition to the microbiological assessment of rainwater samples, we also studied the influence of prevailing air quality on the microbial quality of rainwater over the sampling period. A significant change in the diversity and relative abundance of the basic microbial indicator organisms in rainwater was observed during a major regional air pollution episode in Southeast Asia due to biomass-burning emissions.

Climatic Chamber With Centrifuge to Simulate Different Weather Conditions

Abstract Increasing interest in thermo-hydro-mechanical (THM) studies of soil responses to hydrological variations has heightened the need for improvements in the basic understanding of the heat and mass transport taking place at the soil-atmosphere interface. Numerous hydrological parameters affect this thermo-hydro-mechanical process including solar radiation, air temperature, atmospheric pressure, wind velocity, rain intensity and hygrometry. Since field tests of soil-atmosphere interaction require measurements over long periods of time, only a small number of these results are available for calibration of the numerical models that are based on atmospheric data as boundary condition. The number is even more limited for results which focus on cyclic wetting and drying. Centrifuge modeling is a powerful tool for studying these problems since it can accelerate the time needed for diffusion processes taking place at the soil-atmosphere interface. Nevertheless, modeling this interaction adequately with a centrifuge requires development of new types of equipment such as a climatic chamber that allows control of weather variables while respecting the centrifuge’s scaling laws. This paper describes the design of an apparatus for simulating tropical weather conditions which combines a climatic chamber with a centrifuge. The scaling laws are studied, and the feasibility of reproducing tropical weather conditions around a centrifuge is discussed. Finally, the paper presents some validation results that highlight the working principles of this new apparatus.

Hydration status of heat-acclimatized youth team players during competition

Summary Objective The aim of the study was to investigate the hydration status of heat-acclimatized youth team players during a hockey competition. Method and results Forty male hockey players (age: 12.3 ± 0.5 yrs) had body mass (via weighing scale) and urine specific gravity (UrineSG) (via refractometry) measured immediately pre and post-tournament after playing three matches of 6 min duration on a modified pitch (30 m × 22 m), separated by a rest interval in the shade of 18 min (overall heat exposure was 54 min). The tournament was held in March and during 0830–1130 h in tropical weather conditions (31.5 ± 0.2° C; relative humidity 84.2 ± 0.4%). Chilled mineral water, an isotonic sports drink, a Milo beverage were freely available to players throughout the tournament. Among the players who arrived at the tournament site, 97.5% already showed signs of dehydration (UrineSG > 1.010), increasing to 100% after the tournament. Body mass changes amounted to 3.25% (P Conclusion Individualized player hydration routines and coach education on the importance of hydration before, during and after tournament are recommended.

The detection of post-monsoon tropospheric ozone variability over south Asia using IASI data

Abstract. The ozone (O3) variability over south Asia during the 2008 post-monsoon season has been assessed using measurements from the MetOP-A/IASI instrument and O3 profiles retrieved with the SOftware for a Fast Retrieval of IASI Data (SOFRID). The information content study and error analyses carried out in this paper show that IASI Level 1 data can be used to retrieve tropospheric O3 columns (TOC, surface-225 hPa) and UTLS columns (225–70 hPa) with errors smaller than 20%. Validation with global radiosonde O3 profiles obtained during a period of 6 months show the excellent agreement between IASI and radiosonde for the UTLS with correlation coefficient R > 0.91 and good agreement in the troposphere with correlation coefficient R > 0.74. For both the UTLS and the troposphere Relative Standard Deviations (RSD) are lower than 23%. Comparison with in-situ measurements from the MOZAIC program around Hyderabad demonstrates that IASI is able to capture the TOC inter and intra-seasonal variability in central India. Nevertheless, the agreement is mitigated by the fact that the smoothing of the true O3 profiles by the retrieval results in a reduction of the TOC variability detected by IASI relative to the variability observed by in situ instruments. The post-monsoon temporal variability of the vertical profile of O3 around Hyderabad has been investigated with MOZAIC observations. These observations from airborne instruments show that tropospheric O3 is steadily elevated during most of the studied period with the exception of two sharp drops following the crossing of tropical storms over India. Lagrangian simulations with the FLEXPART model indicate that elevated O3 concentrations in the middle troposphere near Hyderabad are associated with the transport of UTLS air-masses that have followed the Subtropical Westerly Jet (SWJ) and subsided over northern India together with boundary layer polluted air-masses transported from the Indo-gangetic plain by the north-easterly trades. Low O3 concentrations result from the uplift and westward transport of pristine air-masses from the marine boundary layer of the Bay of Bengal by tropical storms. In order to extend the analysis of tropospheric O3 variability to the whole of south Asia, we have used IASI-SOFRID O3 data. We show that IASI O3 data around Hyderabad were able to capture the fast variability revealed by MOZAIC. Furthermore, their spatio-temporal coverage demonstrates that the behaviour of tropospheric O3 observed near Hyderabad extended over most of central and south India and part of the Bay of Bengal. This result highlights the ability of the IASI sensor to capture fast changes in chemical composition related to dramatic tropical weather conditions.

Determination of glyphosate through passive and active sampling methods in a treated field atmosphere

The study was carried out to determine the atmospheric residues of glyphosate (N-phosphonomethylglicine) using both passive and active sampling methods in Malaysia’s tropical weather conditions. The field was treated with Roundup (Monsanto) @ 2L ha-1 using Mistblower (Solo 412). Glyphosate was sampled in 12 h day time pre and post-spray sampling events using three simple and low-cost passive air samplers (cotton gauze, cellulose filter, and PUF) and active sampling using PUF plug and quartz filter cartridges. In pre-spray sampling event, no glyphosate detection was shown in both passive and active sampling. On the other hand, post-spray passive samples data revealed that only cotton gauze among the three passive air samples showed detection in both post-spray events during which the first post-spray (2.49 ng/cm2) showed significantly higher residue measurement than that of second post-spray period (0.84 ng/cm2). In active sampling, however, no glyphosate residue was detected in any of the PUF plug samples but detected only in quartz filter samples, revealing that glyphosate is associated with particles rather than vapour in the air. The highest concentration of glyphosate (42.96µg/m3) was measured in the air at operator’s breathing zoneduring the 25 min spray application period. In the post-spray active sampling periods, glyphosate residue was significantly far below compared to the spray period concentration. Furthermore, in paired comparison between active and passive sampling methods in terms of residue uptake performance, passive sampling showed significantly better performance than the active sampling method in this study. Key words: Glyphosate, active sampling, passive sampling, atmospheric residue.

Transferência de imunidade passiva em cordeiros de corte manejados extensivamente em clima tropical

Aspectos relacionados à transferência de imunidade passiva (TIP) foram estudados em 290 cordeiros recém-nascidos, cruzas Texel, manejados extensivamente em contato permanente com as suas mães, e criados em clima tropical. Amostras de sangue foram colhidas dos cordeiros uma única vez entre 24 e 36 horas de vida para obtenção do soro sanguíneo. Foram determinadas a atividade da gama glutamiltransferase e as concentrações de proteínas totais por refratometria e colorimetria, de albumina, alfa, beta e gamaglobulinas por eletroforese e de IgG estimada pela turvação pelo sulfato de zinco. Os cordeiros foram agrupados de acordo com o sexo, o número de partos das ovelhas, o escore de condição corporal (ECC) da ovelha, o número de cordeiros nascidos, o peso e a vitalidade ao nascimento. Os fatores de risco para a ocorrência de falha na transferência de imunidade passiva (FTIP) foram identificados e a sua associação com a mortalidade de cordeiros foi testada. Foram estabelecidas correlações entre as variáveis estudadas. A TIP não foi influenciada pelo sexo, pelo número de partos ou pelo ECC das ovelhas. Houve diferenças entre os cordeiros únicos e gêmeos e entre os que nasceram com peso >3 kg e < 3 kg. A FTIP foi pouco frequente (12,4%), mais provável em gêmeos (p=0,026) e em cordeiros leves (p<0,001) e esteve fortemente associada com a mortalidade dos cordeiros até os 60 dias de vida (p<0,001). A taxa de mortalidade geral foi de 11,3%; e 30,5% dos cordeiros com FTIP morreram, quase todos no primeiro mês de vida. A concentração de proteína total determinada por refratometria se correlacionou (p<0,001) com as concentrações de gamaglobulinas (r=0,816) e de IgG (r=0,810) e o valor crítico < 5,0g/dL para a proteína total pode ser admitido como indicador de FTIP. Sob condições de clima tropical a FTIP pode ser considerada pouco frequente em cordeiros mestiços de corte, entretanto, a vigilância e os cuidados devem ser intensificados no caso do nascimento de cordeiros gêmeos com peso reduzido.

Pilot-Scale Simulation of Landfill Bioreactor and Controlled Dumping of Fresh and Partially Stabilized Municipal Solid Waste in a Tropical Developing Country

Four pilot-scale lysimeters were used to study the benefits of landfill operation with and without leachate recirculation in tropical weather conditions. Young and old landfills were simulated by filling lysimeters with a segregated fraction of fresh municipal solid waste (MSW) and MSW mined from an open dump site, respectively, and periodically monitoring leachate quantity and quality and biogas quality. For each substrate, one lysimeter was operated as a bioreactor with leachate recirculation and another lysimeter was operated as a controlled dump, for a period of 10 months. Densities between 652 and 825 kg/m3 could be achieved with fresh and mined MSW. Despite such compaction during waste placement, bioreactor technology helps in leachate management, especially in the case of the young landfill lysimeter operated in tropical weather. The benefits of leachate recirculation in the young landfill lysimeter were evident from the significant decrease in chemical oxygen demand (COD) (86%), biochemical oxyge...

COMPARAÇÃO DE MÉTODOS PARA ESTIMATIVA DO PLASTOCRONO EM ALGODOEIRO EM CONDIÇÕES TROPICAIS

The time for growth and development of plants is influenced by air temperature and other environmental variables. This research was based on three methods for calculating plastochron timing of cotton plant under tropical weather conditions, using thermal units accumulation as variable, calculated from the average daily air temperature, considering the concepts of degrees-day and accumulated thermal time. Two methods for calculating average daily temperature and three methods for obtaining Degrees-Day values and accumulated thermal time were used. Whereas the accumulated thermal time is a method that considers that the growth and development of plants have linear response to the air temperature influence, it was also tested a non-linear approach, as described by Wang & Engel (1998), called, in this study, beta function. For the beta function, average daytime temperatures were also used, obtained by the two different calculation methods. The beta function was the best option for estimating plastochron and the method for calculating the Average Daily Temperature influenced the results. KEY-WORDS: Gossypium hirsutum ; degrees-day; beta function; physiological age; thermal units.

Serological Survey of American Trypanosomiasis in Dogs and Their Owners From an Urban Area of Mérida Yucatàn, México

American trypanosomiasis is an important zoonotic disease which affects more than 15 million persons in America. In Mexico, Chagas' disease is widely distributed in the country mostly in states with tropical weather conditions, including Yucatan. A cross-sectional study was performed on serum samples from 35 dogs and their owners (n = 75) from the south area of Merida city. Specific IgG antibodies against Trypanosoma cruzi (T. cruzi) using enzyme-linked immunosorbent assay, Immunofluorescence antibody test (IFI) and Western blot (WB) were detected. The overall percentage of seropositivity was 34% in dogs and 8% for sampled owners. Some owners brought samples of insect vectors found in their households, which were kept with BALB/c mice as a source of food and which were evaluated by polymerase chain reaction. All tested insects were positive to T. cruzi, and BALB/C mice were IFI and WB positive after 45 days in contact with these vectors. Further investigations showed that there is a high risk of infection with Chagas disease in dogs which spend the night outdoors (P < 0.05), with low body conditions score and older dogs. Risk factors identified to be associated to the infection in owners were gender and occupation (bricklayers, P < 0.05). The presence of seropositive dogs in houses where vectors are well-adapted represents a high risk for humans to become infected when bitten by a vector infected by a positive dog.

Thin layer solar drying characteristics of silkworm pupae

Thin layer solar drying experiments of silkworm pupae using a solar tunnel dryer were conducted under the tropical weather conditions of Mahasarakham, Thailand. The dryer consisted of a transparent glass covered flat-plate collector and a drying tunnel connected in series to supply hot air directly into the drying tunnel using a blower. During the experiments, silkworm pupae were dried to the final moisture content of 0.15 kg water kg −1 dry matter from 4.37 kg water kg −1 dry matter in 373 min at the corresponding air flow rate of 0.32 kg s −1. Ten different thin layer drying models were compared according to their coefficient of determination to estimate drying curves. The Midilli–Kucuk model precisely represents the solar tunnel drying behavior with the coefficient of determination ( R 2) of 0.9982. The maximum drying rate and effective moisture diffusivity were 0.6723 kg water kg −1 dry matter h −1 and 2.7696 × 10 −10 m 2 s −1, respectively, on the drying air flow rate of 0.32 kg s −1. A quality assessment shows that the lipid content of the dried silkworm pupae was not affected by the solar tunnel dryer. A slight decrease of polyunsaturated fatty acid (PUFA) was observed.

Ciclo de vida de Heterodera glycines raça 9 em soja no Estado do Maranhão

O nematóide de cisto da soja, Heterodera glycines, causa consideráveis reduções de produtividade à cultura da soja. Ocorrem 11 raças do NCS no Brasil e, no Maranhão, há registro somente da raça 9. O objetivo deste trabalho foi estabelecer o ciclo de vida de uma população de H. glycines raça 9, em soja, sob condições de clima tropical. O ensaio foi conduzido em casa-de-vegetação telada, no Campo Experimental da Embrapa Soja, em Balsas, Maranhão. As médias de temperaturas neste período foram de 28,7 °C no solo e 31,7 °C no ar e a média da umidade relativa do ar foi de 49,8 %. Plântulas de soja BRS Sambaíba foram transplantadas para vasos contendo solo areno-argiloso infestado com 4000 ovos de H. glycines raça 9. Foram avaliados os números de fêmeas e de cistos por sistema radicular aos 17, 20, 23, 26, 29 e 32 dias após a infestação. O número médio de fêmeas por sistema radicular de soja aumentou significativamente entre o 17º e o 29º dia após a infestação do solo, diminuindo no 32º dia, quando começaram a surgir os primeiros cistos. Nas condições testadas, H. glycines raça 9 completou o ciclo de vida em 29 dias após a infestação do solo. Desta forma, é possível a ocorrência de 3 a 4 gerações do nematóide durante o ciclo da soja em Balsas, Maranhão.

Experimental performance of a solar tunnel dryer for drying silkworm pupae

The objective of this study was to conduct an experimental analysis to investigate the performance of a mixed mode type forced convection solar tunnel dryer (STD) which was used to dry silkworm pupae under tropical weather conditions of Mahasarakham, Thailand. The dryer consisted of a transparent glass covered flat-plate collector and a drying tunnel connected in series to supply hot air directly into the drying tunnel using a blower. The dryer was 6.2 m long and 1.8 m wide. The drying unit had a loading capacity of 30 kg of silkworm pupae. The effect of the drying air flow rate was examined. The drying time depended on the drying air flow rate and temperature. Moisture content of the silkworm pupae was reduced from 3.70 kg H2O kg−1 dry matter to 0.20 kg H2O kg−1 dry matter in 570 min at the corresponding air flow rate of 0.30 kg s−1 and it took 945 min in open sun drying; drying time was reduced by about 40%. A quality assessment shows that the lipid content of the dried silkworm pupae was not affected by the STD. A slight decrease of polyunsaturated fatty acid (PUFA) was observed. Maximum drying and overall efficiencies were 30.14% and 19.68%, respectively, at the air flow rate of 0.30 kg s−1. The economic analysis indicates that the payback period is 1.42 years. Due to its simplicity, the proposed system is relatively inexpensive. Therefore, commercial application seems to be viable.

Equine parascarosis under the tropical weather conditions of Ethiopia: a coprological and postmortem study

A cross-sectional coprological survey in the regions of Ada, Akaki, Bereh and Boset, and a retrospective postmortem investigation were conducted to study the epidemiology of Parascaris equorum in donkeys and horses in Ethiopia. Faecal samples from 803 working donkeys and 402 horses were collected, and the numbers of worms recovered from 112 donkeys examined postmortem between 1995 and 2004 were analysed. There was a high prevalence of infection and faecal egg output of P equorum in both donkeys and horses, and the severity of the infection in donkeys was increased irrespective of their age. The prevalence of the infection in the donkeys was 51.1 per cent and in the horses 16.2 per cent, and the prevalence in the donkeys examined postmortem was 55 per cent. There was no significant difference between different age groups of donkeys in either the prevalence or the intensity of the infection. The prevalence of the infection was significantly higher in the Ada and Akaki regions than in the Bereh and Boset regions.

An integrated stormwater management approach for small islands in tropical climates

In many tropical island settings in the world and as a result of human activities and tropical weather conditions, urban areas have been vulnerable to special kinds of hazards. The most common and the most widely experienced hazard events for these localities are tropical cyclones and accompanying storm surges, flash floods and landslides. Such events can cause serious damages to the drainage systems, roads, properties, receiving environment and even the loss of human lives. Given the threats of climate change, such natural disasters are likely to strengthen this trend in the coming years. In many situations, it is the population living in low-lying urban areas that are most exposed to these disasters. From this, it follows that the scientific and professional communities have a responsibility to evolve better stormwater management approaches directed to minimizing hazard risks owing to urban flooding, even while addressing different climatic conditions. Although, the physics, chemistry and biology of processes related to water are universal, some of the processes and implementation of measures to manage water vary in terms of the climate conditions, geographical location, availability of resources and local culture. In tropical island conditions, where flash floods occur frequently, alongside the obvious structural measures, effective non-structural measures, such as better hazard mitigation and prevention, improved preparedness and introduction of warning systems, well organised pre-emptive action and emergency response activities, have to be coupled together in order to minimize damages. Furthermore, as the management of urban flooding is an emerging subject, it is necessary to understand that such a topic needs to be treated holistically, and so in a multi-disciplinary manner. This implies that the public, town planners, economists, lawyers, emergency services, and many other groups need to be involved, along with the engineers, surveyors and contractors, in developing strategic plans for hazard reduction, operational management and post-event recovery. Thus the stakeholders have to be involved in the decision-making processes (e.g., Abbot 2007, available at www.eiil.net). The present paper describes an integrated stormwater management approach oriented towards the small islands in tropical climates which continuously tend to suffer from flash floods. The approach outlined here draws on the work experiences gained in the Caribbean.

Drying of hot chilli using solar tunnel drier

A mixed mode type forced convection solar tunnel drier was used to dry hot red and green chillies under the tropical weather conditions of Bangladesh. The drier consisted of transparent plastic covered flat-plate collector and a drying tunnel connected in series to supply hot air directly into the drying tunnel using two fans operated by a photovoltaic module. The drier had a loading capacity of 80 kg of fresh chillies. Moisture content of red chilli was reduced from 2.85 to 0.05 kg kg −1 (db) in 20 h in solar tunnel drier and it took 32 h to reduce the moisture content to 0.09 and 0.40 kg kg −1 (db) in improved and conventional sun drying methods, respectively. In case of green chilli, about 0.06 kg kg −1 (db) moisture content was obtained from an initial moisture content of 7.6 kg kg −1 (db) in 22 h in solar tunnel drier and 35 h to reach the moisture content to 0.10 and 0.70 kg kg −1 (db) in improved and conventional sun drying methods, respectively. The use of a solar tunnel drier and blanching of sample led to a considerable reduction in drying time and dried products of better quality in terms of colour and pungency in comparison to products dried under the sun. The solar tunnel drier and blanching of chilli are recommended for drying of both red and green chillies.

Indonesian smoke aerosols from peat fires and the contribution from volcanic sulfur emissions

The island arc volcanoes in and around Indonesia have been permanently degassing for thousands of years, thereby contributing significantly to the total emissions of sulfur species in that region. The hot and wet tropical weather conditions with high solar irradiation and regular daily precipitation during the wet season lead to efficient removal of oxidised sulfate by wet deposition. This is accumulated in the Indonesian peat areas, which serve as natural sponges, soaking up rain during the wet season and slowly releasing moisture into the atmosphere during the dry season. When peat forests are drained for land clearing purposes, the peat quickly dries out and becomes extremely flammable. When ignited, the composition of the burning peat mainly determines the fire aerosol chemical composition and microphysical properties. In this paper we investigate the contribution of volcanic sulfur emissions to wet deposition of sulfur in Indonesian peat swamp areas based on numerical simulations carried out with a global atmospheric circulation model including the tropospheric sulfur cycle. Our study suggests that the observed hygroscopicity and elevated sulfur content of the Indonesian peat fire aerosols is due to accumulated volcanic sulfur.

Development of a multi-purpose solar tunnel dryer for use in humid tropics

Particularly in tropical countries, a high percentage of crops are spoiled during the drying period due to permanently high relative humidity and sudden rainfalls. Open air sun drying and smoke drying, which are traditional drying methods in these regions, lead to insufficient product quality. In order to be marketable, the produce meant for sale on the world market has to meet high quality standards. Otherwise the price will decline resulting in low profits for the exporting country and the producing farmer. To produce high quality products for the world market as well as to reduce losses, the development of suitable dryers for tropical regions is urgently needed. A multi-purpose solar tunnel dryer, orginally developed for the use in arid zones, was modified to enable operation under tropical weather conditions. This type of dryer consists of a small centrifugal blower, a collector and a tunnel drying chamber. To prevent penetration of water into the construction and subsequent flooding, the solar dryer was installed on a wooden substructure. To heat the drying air during cloudy and rainy days, particularly in the rainy season, a biomass furnace with heat exchanger was integrated into the solar drying system. The construction consists exclusively of materials available in Java. Only low energy requirements are necessary to run the blower. Results showed that compared to natural sun drying, the drying time of cocoa, coffee and coconut could be reduced up to 40%. Solar drying improves the quality of the products in terms of colour, flavour and appearance, reduces the risk of microorganism growth, prevents insect infestation and contamination by foreign matters and mycotoxins. The products dried with the solar drying system meet the national and ingternational market standards. Investigations further showed that even during the rainy season it was possible to dry the products to the final moisture content which is needed for storage and marketing. The modular system allows adaptation to different farm sizes as well as cooperative use.

The Long Rapids Formation: an Upper Devonian black shale in the Moose River Basin, northern Ontario

The Long Rapids Formation, a sequence of interbedded black shales, green–grey mudstones, and carbonates in the Moose River Basin of northern Ontario, is Late Devonian in age and has counterpart equivalents in the Michigan, Appalachian, and Illinois basins. The Long Rapids Formation has a maximum known thickness of 85 m and can be divided into three informal members. Based on conodont studies, the formation spans the Frasnian–Famennian age boundary.The Long Rapids Formation is an organic-rich, laminated, marine black-shale sequence interbedded with green–grey mudstones and concretionary carbonate interbeds and nodules. The environment of deposition was principally reducing, allowing for preservation of large amounts of organic matter both originating in the overlying water column and derived from terrestrial sources. The depositional basin was stratified, and anoxic bottom waters and oxic surface waters were separated by a pycnocline. The position of the pycnocline (or the absence of it) dictated the type of sediment facies deposited.The Moose River Basin in the Late Devonian was located on the Laurasian Continent, proximal to the equator, in an area where tropical weather conditions prevailed. Conditions were warm and wet along the Appalachian highlands, and farther inland they were warm and dry as a result of the rain-shadow effect. The black shales in the Long Rapids Formation represent a period of transgression of the large epicontinental Catskill Sea, and the green–grey mudstones and carbonates represent periods of minor eustatic or tectonic perturbations.Dark-coloured, organic-rich shale facies (sometimes with abundant bioturbation) are succeeded by lighter coloured shale or mudstone facies and carbonate facies in a repetitive fashion. The facies sequences appear to represent a three-part sedimentary package, or "rhythm", that is very common in the lower two members of the Long Rapids Formation. Bioturbation and total organic carbon content are less in the green–grey shales or mudstones, as well as in the carbonate facies, than in the darker shale facies.

Chemical oxidation and spectral selectivity of austenitic stainless steel AISI 321 (for use in solar-energy applications)

Polished samples of austenitic stainless steel AISI 321 were chemically oxidized in 0.1–0.6 M aqueous solutions of chromic and sulphuric acids at 90 °C for an oxidation time of 25 min, as well as for oxidation times ranging from 10 to 32 min in 0.6 M solution. Chemical oxidation of the stainless steel produced interference films ranging in colour from light-blue to deep-blue, purple-red and peacock-green. Measurements of solar absorptance ( α s ) and total hemispherical thermal emittance ( ϵ h ) showed that all the oxidized surfaces were spectrally selective. The most favourable spectrally selective surface was deep-blue in colour and it had values of α s = 0.85 ± 0.01 and ϵ h = 0.18 ± 0.01. This surface was prepared after an oxidation time of 12 min at a concentration of 0.6 M of chromic and sulphuric acids. For the unoxidized polished stainless steel, the α s and ϵ h were 0.38 ± 0.01 and 0.15 ± 0.01 respectively. No significant changes in the optical properties of the films were observed after 6 months exposure to highly humid tropical weather conditions.