Identification of non-precious metal alloy catalysts for selective hydrogenation of acetylene

The removal of trace acetylene from ethylene is performed industrially by palladium hydrogenation catalysts (often modified with silver) that avoid the hydrogenation of ethylene to ethane. In an effort to identify catalysts based on less expensive and more available metals, density functional calculations were performed that identified relations in heats of adsorption of hydrocarbon molecules and fragments on metal surfaces. This analysis not only verified the facility of known catalysts but identified nickel-zinc alloys as alternatives. Experimental studies demonstrated that these alloys dispersed on an oxide support were selective for acetylene hydrogenation at low pressures.     

Struktur und Langzeitentwicklung von subalpinen Pinus montana Miller und Pinus cembra L. W?ldern in den zentraleurop?ischen Alpen

Zusammenfassung:  Die traditionelle land- und forstwirtschaftliche Nutzung dürfte im Alpenraum in der näheren Zukunft wirtschaftlich bedingt immer häufiger aufgegeben werden. Dieser Trend wird mit großer Wahrscheinlichkeit die Dynamik von Gebirgsökosystemen und damit das Landschaftsbild stark beeinflussen. Aus diesem Grund stieg in den letzten Jahrzehnten das Interesse, die Sukzession auf nicht mehr bewirtschafteten Flächen zu verstehen. Die Bestandesstruktur und -entwicklung von subalpinen Fichtenwäldern (Picea abies L.) wurde bereits intensiv untersucht; über Entwicklungsprozesse in zentralalpinen Bergföhren- (Pinus montana Miller) und Arven-/Lärchenwälder (Pinus cembra L./Larix decidua L.) ist hingegen nur wenig bekannt. Der seit 1914 vom Menschen nur noch touristisch genutzte Schweizerische Nationalpark (SNP) ist eines der wenigen Gebiete in Westeuropa, welches über längere Zeit nicht bewirtschaftet wurde. Der Park bietet daher die einzigartige Möglichkeit, die Veränderungen in Bestandesstruktur und -zusammensetzung nach Bewirtschaftungsaufgabe zu beobachten. Wir verglichen historische (1957) und aktuelle (2001/02) Daten von 19 Beständen, welche zu drei verschiedenen Bestandestypen gehören: Bergföhre, Mischbestand und Arve. In den letzten 45 Jahren nahm die totale Stammzahl in allen drei Bestandestypen um 45 bis 57% und die Jungbaumzahl pro Hektar um 64 bis 76% signifikant ab, was vor allem auf den starken Rückgang der lichtbedürftigen Bergföhre zurückzuführen ist. Parallel zu dieser Entwicklung, nahm die Menge an liegendem Totholz in allen Bestandestypen von weniger als 4t/ha auf 36 bis 67,7t/ha zu, während die Anzahl toter Bäume pro Hektar um 72 bis 94% abnahm. Die Biomasse des stehenden Totholzes (t/ha) hat sich hingegen nur leicht verändert. Unsere Resultate beschreiben die sukzessionale Entwicklung von subalpinen Wäldern der Zentralalpen und zeigen, wie sich Wälder in ähnlichen Berggebieten in der nahen Zukunft entwickeln könnten.

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Summary:   Since traditional agriculture and forestry are no longer economically viable in many regions of the European Alps, subalpine forests will become less managed or completely abandoned in the near future. Therefore, the interest in understanding how forest stands will develop after abandonment has increased considerably over the past two decades. While much is known about stand structure and stand development of Norway spruce (Picea abies L.) forests, almost no knowledge is available about the same processes in forest communities of the Central Alps. In the Swiss National Park (SNP), the forested area is comprised of mountain pine (Pinus montana Miller), Swiss stone pine/larch, (Pinus cembra L./Larix decidua L.). and mixed stands. When the Park was founded in 1914 all management activities were stopped. Therefore, this area offers the opportunity to study stand development and changes in stand structure after abandonment. We compared historic (1957) and present data (2001/02) from 19 stands that were grouped into characteristic stand types: mountain pine, mixed, and stone pine. We detected significant decreases in total tree density (stem/ha) and sapling density (saplings/ha) of 45 to 57%, and 64 to 76%, respectively, over the 45 years of observation for all stand types. These changes were strongly related to decreases in the number of shade intolerant mountain pine trees. Simultaneously, the amount of non-standing woody residue increased from less than 4t/ha to 36 to67.7 t/ha, and the density of standing dead wood (stems/ha) decreased significantly between 72 and 94%. The biomass of standing dead wood (t/ha), however, changed only slightly between 1957 and 01/02. Our results describe the successional development of continental subalpine forests after abandonment and outlines changes that might take place in similar areas in the near future.

     

Residual macronutrient concentration and follower maize (<Emphasis Type="Italic">Zea mays</Emphasis>) crop performance in soilless growth medium previously cropped with six <Emphasis Type="Italic">Musa</Emphasis> genotypes

The nutrient mining abilities of six Musa genotypes: ‘Agbagba’, ‘PITA 22’, ‘Nsukka Local’, ‘FHIA 17’, ‘Fougamou’, and ‘BITA 7’, grown in organic medium formulated by decomposing rice husks with poultry manure in volume proportions of 3:2, were determined at the Teaching and Research Farm of the Department of Crop Science, University of Nigeria, Nsukka, Nigeria. Results indicated significant variation in nutrient mining with respect to Musa genotype and duration of growth. The medium previously cropped with ‘Agbagba’ recorded highest residual mean values for P and Ca, while the medium cropped with ‘Fougamou’ had the highest residual concentration of Mg and S. Residual amount of K was highest in the medium where ‘PITA 22’ and ‘Nsukka Local’ were previously grown. Peak residual concentration of P and K occurred in the medium in which Musa plants were grown only for 4 months, decreasing thereafter, in contrast to Ca, Mg, and S. Residual N tended to increase with longer growth duration of the Musa crops. Follower crop of maize grown in the medium previously cropped with Musa genotypes showed variable performance. While medium previously cropped with ‘PITA 22’ and ‘BITA 7’ favored growth attributes and leaf greenness of the follower maize plant, ‘Fougamou’ favored maize fresh weight attributes. Ectomycorrhiza association was observed in medium previously cropped to ‘BITA 7’ and ‘PITA 22’. Generally, ‘Agbagba’ and ‘Fougamou’ seemed to be the most reticent nutrient miners while uptake of P and K appeared to be low 4 months after planting (MAP) in contrast to Ca, Mg, and S uptake. However, substrate previously cropped with ‘PITA 22’, ‘BITA 7’ and ‘Fougamou’ gave rise to superior growth and fresh weight attributes, respectively, of the maize, the follower crop. A prospect of utilizing the ectomycorrhiza association observed with some genotypes to upgrade Musa yields and those of associated or follower crops exist.     

Assessment of Mobile Phone Usage Among Farmers in Keana Local Government Area of Nasarawa State,Nigeria

This study assessed the usage of mobile phones among farmers in the Keana Local Government Area of Nasarawa State, Nigeria. One hundred and fifty-eight respondents were selected using purposive and random sampling techniques. Primary data were used, and collected using a structured questionnaire. Research revealed that a majority of the respondents (60.1%) had a medium level of use of mobile phones. The mobile phone network preferred by respondents was MTN (32.3%). The major factor affecting the use of mobile phones is poor network coverage (22.1%). Possession of formal education, income, and sex of the respondents significantly affected their level of use of mobile phones. It is therefore recommended that network providers be supervised by the Government to ensure quality service delivery, and other network providers encouraged to improve on their services.     

Sorption and fate of perchlorate in arid soils

The mobility of perchlorate in soils depends on several factors, including soil mineralogy and the presence of other oxyanions that compete with perchlorate for the retention sites. Currently, there are no studies that evaluate the mobility of perchlorate in arid soils. The present study evaluated the mobility of ClO₄^– in three arid soils, Canchones, Humberstone and Pica, exposed to two ClO₄^– concentration ranges and different ionic strengths. In Humberstone (non-agricultural) and Pica (agricultural) soils, the sorption processes were not important for both concentration ranges, while Canchones soil (agricultural) showed a decrease in perchlorate concentration associated with microbial degradation processes. The increase of medium ionic strength by addition of Ca(NO₃)₂ only had an important effect on Humberstone soil, associated with the presence of kaolinite and muscovite (variable charge). A competition effect was observed between perchlorate, nitrate and other anions presents in solution by absorption sites generated from variable charge mineral and calcium. Considering the quite low sorption capacity of the soils and the high solubility, perchlorate can be absorbed by fruit and vegetables of export in concentrations over the healthy levels established by international organization.     

Antioxidant systems and their relationship with the response of pepper fruits to storage at 20 degrees C

Fresh peppers (Capsicum annuum L., variety California) in their green and red ripe stages were stored at 20 degrees C for 7 and 19 days to determine the effects of storage on whole fruit antioxidant capacity (TAA) and ascorbate (ASC) content, as well as on some antioxidant enzyme activities, such as catalase (CAT), superoxide dismutase (SOD), and those of the ASC-glutathione cycle. At least one Mn-SOD, two Fe-SODs, and three CuZn-SODs were detected in the fruit extract after native polyacrylamide gel electrophoresis. All of the SOD isozymes and glutathione reductase had higher activity levels in the red control fruits than in the green fruits, whereas the activities of monodehydroascorbate and dehydroascorbate reductase were higher in green fruits. Ascorbate peroxidase (APX) was found to be similar in both fruits. SODs, CAT, and APX seem to be involved in pepper fruit ripening and senescence during storage at 20 degrees C, perhaps influencing the active oxygen species levels in the fruit. TAA, as well as the ASC content, was higher in red peppers than in green, and storage increased the ASC in both green and red fruits.     

Application of an electronic micropenetrometer to assess mechanical stability of biological soil crusts

An in situ determination of biological soil‐crust stability was carried out in two study sites along a sharp rainfall gradient. Penetration resistance (PR) of the crusts was measured using a newly developed light‐weight needle‐type electronic micropenetrometer. The depth‐related PR data revealed two sections possessing different structures and stability. The topcrust (0–2 mm) had significantly higher amounts of N, organic C, carbonates, and salts as compared to the underlain subcrust. The mean PR of the topcrust was 0.68 MPa for the southern study site, Nizzana‐South (≈ 100 mm annual rainfall), and it increased significantly for the northern study site, Nizzana‐69 (≈ 170 mm annual rainfall), with a mean of 1.11 MPa. A subcrust (2–30 mm) was identified that was characterized by a high amount of carbonates and a PR > 2 MPa. The electronic micropenetrometer system is a promising device for identifying areas of changing crust stability in relation to biological soil‐crust properties. The overall stability of biological soil crusts depends on the topcrust and subcrust structure. This structure is linked to abiotic and biotic factors and likely in relation to the amount of annual precipitation.     

Anatomical and surface ultrastructural investigation of the tongue in the straw-coloured fruit bat (Eidolon helvum,Kerr 1972)

The morphology of tongue in straw-coloured fruit bat from tropical forests was evaluated in relation to frugivorous diets and in comparison with other species that consumes other food types. Gross, stereomicroscopy, scanning electron microscope and histological methods were used. The tongue was relatively long with round tip, which closely fitted into oral cavity. Five types of mechanical papillae included crown-like and trifid filiform papillae. Also bulky, cone-shaped papillae and long conical papillae were identified. These mechanical types also showed variations in shape, size and number of processes of papillae. Transitional forms of these mechanical papillae were present. Fungiform papillae with taste pores were interposed amongst filiform types in apex and body; three ovoid-shaped vallate papillae were in triangular arrangement on root and displayed taste pores. Some bulky, cone-shaped papillae surrounded the vallate papillae. Histologically, mechanical filiform types showed highly keratinized stratified squamous epithelium and dense connective tissue core with secondary papillae. Taste buds appeared in fungiform and vallate papillae. Neutral and acidic secretions were identified in lingual glands of root. The presence of prominent filamentous processes of filiform papillae and conical papillae of the tongue in conjunction with gustatory papillae ensures adaptation to copious fruit diets. The gross morphometric and histometric parameters of the tongue did not differ remarkably from previous values obtained for some fruit bats with comparable weight. This investigation showed similarities with fruit bats such as large flying fox and Egyptian fruit bat and reflect common diet and feeding habits but varied from insectivorous and nectivorous bats.     

Winter-feeding systems for gestating sheep II. Effects on feedlot performance, glucose tolerance, and carcass composition of lamb progeny

Mature pregnant crossbred ewes (n = 90) were used in a randomized complete block design experiment and were assigned to 1 of 3 winter-feeding systems differing in primary feed source: haylage (HL), limit-fed corn (CN), or limit-fed dried distillers grains (DDGS). Effects of these winter-feeding strategies on postweaning progeny performance were determined. Lamb progeny (n = 96) were weaned at 61 ± 4 d of age and fed a common high-concentrate diet. Lambs were assigned to feedlot pen (n = 18) based on dam mid-gestation pen. Growth rate, DMI, and ADG were determined for the first 40 d of the finishing period. At 96 ± 4 d of age, 1 wether lamb was randomly selected from each pen (n = 18) for a glucose tolerance test. The experiment was terminated, and lambs were slaughtered individually when they were determined to have achieved 0.6-cm 12th-rib fat thickness. After a 24-h chill, carcass data were collected and a 2.54-cm chop was removed from each lamb from the LM posterior to the 12th rib for ether extract analysis. Additional carcass measurements of bone, muscle, and fat from the shoulder, rack, loin, and leg were collected on 35 carcasses. At weaning, lamb BW was not different among treatments, whereas final BW tended to be greater (P = 0.09) for lambs from ewes fed DDGS and CN during gestation than from those fed HL. Overall lamb growth rate from birth to slaughter was not different among treatments. Lambs from ewes fed DDGS vs. CN or HL tended to have a greater initial insulin response (P = 0.09). Dressing percent was less (P = 0.04) in lambs from ewes fed DDGS, but no difference (P = 0.16) was detected in HCW among treatments. As expected, 12th rib fat thickness was similar among treatments, whereas LM area was largest to smallest (P = 0.05) in lambs from ewes fed CN, HL, and DDGS, respectively. Proportion of internal fat tended to be greatest to smallest (P = 0.06) in lambs from ewes fed DDGS, CN, and HL, respectively. Calculated boneless trimmed retail cuts percentage was less (P = 0.04) in lambs from ewes fed DDGS than CN or HL. Loin muscle weight as a percentage of wholesale cut tended (P = 0.10) to be greater in lambs from ewes fed CN and HL than DDGS, whereas other muscle, bone, and fat weights and proportions were similar (P > 0.24) among treatments. Prepartum diet during mid to late gestation of ewes altered postnatal fat and muscle deposition and may be associated with alterations in insulin sensitivity of progeny.