Operational characteristics of four metering systems for agricultural fertilizers and amendments

The use of fertilizers and solid amendments in agriculture generates special interest for their effect on crop productivity, as well as for their environmental impact. The efficient use of these products demands knowing their physical and mechanical properties, the storing conditions effect and the operational characteristics of the metering systems used in the fertilizing equipment. In this context, the present study was developed with the purpose of evaluating the operational characteristics of different fertilizing metering systems and to determine the adequate metering system-product operational parameters, using powder lime, powder gypsum, granular 10-30-10 (N-P-K), and granular urea. Operational differences were established among four types of commercial fertilizer metering systems, including wire auger, star-shaped feed wheel, feed screw and ridged traction wheel. The study found that the unloading rate depends directly on the fertilizer metering system's rotating speed and is affected by particle size, repose angle, bulk density and moisture content of the applied product. The wire auger and star-shaped feed wheel metering systems were adequate for the distribution of powder products and the feed screw for granulated fertilizers. Furthermore, theoretical and experimental characteristic equations were established, defining curves for calibration and handling of the products plus the rotating speed range in which a better distributing behavior was achieved.

Obstruction of drippers as a result of application of moisturized whitewash in irrigation water

Plug dynamics of non compensate drip tubes were evaluated, by the precipitation of moisturized whitewash [Ca(OH)2], which is used in the fertigation for the bulb pH control of the trademarks Azud, Amanco, Naandan, Netafim, Petroisa, Queen Gil, with flow rate varying between 0.4 to 3.0 L h-1 usually used in the country. For this matter, increasing doses of Ca(OH)² were applied in the irrigation water, from 0.01 g L-1 to 1.84 g L-1. The flow rate of each drip tube was measured in intervals of time initially of 7 days, later of 15 days of system operation, totaling a time of 100 days of operation, corresponding to nine applications or 432 hours. The coefficient of variation (CV), and relative rate flow (Qr) were evaluated. The results pointed differences among the evaluated emitter regarding the occurrence of the clogging, and the models G2 and G5 presented the smallest levels of flow rate variation comparing to the models G6, G7 and G9.

A new species of Bulbophyllum Thouars (Orchidaceae) from Minas Gerais, Brazil

During the taxonomic revision of the Neotropical Bulbophyllum (Orchidaceae) species, a new species was discovered from Bom Sucesso, Minas Gerais State, described and illustrated here as B. hatschbachianum E. C. Smidt & Borba. This species belongs to the Neotropical section Xiphizusa (Rchb. f.) Cogn. and posses a lip epichile completely different from the related species. It is closely to B. plumosum (Barb. Rodr.) Cogn. due to its vegetative morphology, but has different flower size, color and lip epichile. In B. plumosum the epichile is thin, longer and wider than the hipochile. In B. hatschbachianum the epichile is fleshy, shortest than the hipochile, thin, and sharply narrower than the hipochile. The flowers of this new species is similar to the Mexican B. solteroi R. González, but the general morphology of the lip, trichome size and the geographical distribution clearly distinguishes apart the two species.

Application of a modified sequential organ failure assessment score to critically ill patients

The purpose of the present study was to explore the usefulness of the Mexican sequential organ failure assessment (MEXSOFA) score for assessing the risk of mortality for critically ill patients in the ICU. A total of 232 consecutive patients admitted to an ICU were included in the study. The MEXSOFA was calculated using the original SOFA scoring system with two modifications: the PaO2/FiO2 ratio was replaced with the SpO2/FiO2 ratio, and the evaluation of neurologic dysfunction was excluded. The ICU mortality rate was 20.2%. Patients with an initial MEXSOFA score of 9 points or less calculated during the first 24 h after admission to the ICU had a mortality rate of 14.8%, while those with an initial MEXSOFA score of 10 points or more had a mortality rate of 40%. The MEXSOFA score at 48 h was also associated with mortality: patients with a score of 9 points or less had a mortality rate of 14.1%, while those with a score of 10 points or more had a mortality rate of 50%. In a multivariate analysis, only the MEXSOFA score at 48 h was an independent predictor for in-ICU death with an OR = 1.35 (95%CI = 1.14-1.59, P < 0.001). The SOFA and MEXSOFA scores calculated 24 h after admission to the ICU demonstrated a good level of discrimination for predicting the in-ICU mortality risk in critically ill patients. The MEXSOFA score at 48 h was an independent predictor of death; with each 1-point increase, the odds of death increased by 35%.

Microfibers for juice analysis by solid-phase microextraction

In view of the interest in analyzing volatile compounds by SPME, the following five microfibers were tested, polydimethylsiloxane; polyacrylate; polydimethylsiloxane/divinylbenzene; carboxen/polydimethylsiloxane, and carbowax/divinylbenzene, to select the one which presents the best performance for the adsorption of the volatile compounds present in the headspace of acid lime juice samples. Sample stabilization time variations (30 and 60 minutes) were assessed as well the addition of NaCl to the samples. It was verified that the chromatogram with the most adsorbed volatile compounds was obtained with PDMS/DVB microfiber at 30 minutes and the addition of 0.2 g NaCl.

Whole and crushed nutlets of chia (Salvia hispanica) from Mexico as a source of functional gums

The objective of this study was to characterize the chemical and functional properties of Mexican chia (Salvia hispanica) gums extracted from defatted whole and crushed nutlets using the Soxhlet and SFE-CO2 methods. Chia gums have interesting chemical and functional properties for the food industry. The oil and gum yields were in the range of 1.98-16.42% and 5.81-12.60%, respectively. The defatting procedure did not affect significantly the oil and gum extraction; the nutlet type (whole or crushed) was the only parameter influencing the yield. The proximate composition and the protein and fiber contents of chia gum were evaluated. Low contents of protein and fiber and high NFE levels were found in whole nutlet gums. The functional properties of chia gum extracted from whole and crushed nutlets with the Soxhlet and SFE-COs methods showed the following ranges of water absorption capacity of 62.64 to 143.66 g/g, water adsorption capacity of 0.69 to 1.35 g/g, and water and oil holding capacity of 100 to 149.28 g/g and19.5 to 40.4 g/g, respectively. The rheological behavior exhibited by the gums was pseudoplastic or shear thinning. From a functional perspective, chia gum is an important food component due its emulsifier and stabilizer potentials.

Manufacturing real wages in Mexico

In this paper we analyse the recent evolution and determinants of real wages in Mexico’s manufacturing sector, using theories based on the assumption of imperfect competition both in the product and in the labour markets, especially wage-bargain theory, insider-outsider and mark-up models. We show evidence that the Mexican labour market does not behave as a traditional competitive market. The proposed explanation for this fact is that some workers benefit from advantages when compared with others, so that they can get a greater share of the proceedings of the productive process. Also, we find that changes in the degree of competition in the market for output influence the behaviour of real wages.