The evaluation and adoption of annual legumes by smallholder maize farmers for soil fertility maintenance and food diversity in central Malawi

We studied the process of assessment and adoption of 10 grain- and green-manure legumes by smallholder maize farmers differing in resource endowment in Chisepo, central Malawi. The legumes had been promoted with the farmers from 1998 to 2004, primarily as a way to diversify food production and maintain the fertility of their soils. Farmers (n?=?136) were surveyed in 2004 at the end of the period of promotion to assess the degree of awareness and uptake of the legumes and the reasons for adoption. A follow-up survey was conducted in 2007 among a broader sample of Chisepo farmers (n?=?84) to measure the persistence of adoption. An Analytic Hierarchy Process (AHP) was used in 2004 to create scales of priority and as a tool to compare predicted with actual legume uptake. Actual adoption of food grain legumes reflected predictions by the AHP but it over-predicted uptake of the non-food legumes. The AHP helped us understand how farmer perceptions and needs influence adoption, as well as limitations with the legumes. Suitability for food was the most important criterion that farmers identified for adoption, followed by contribution to soil fertility and suppression of weeds. Over 75 % of the farmers surveyed in 2004 were aware of most of the legumes. Frequent use of the grain legumes was reported in 2004 (79 % for CG7 groundnut, 77 % for soyabean and 47 % for pigeonpea) by both the better-resourced (wealthier) and less-well-resourced (poorer) farm households. Awareness rose to over 90 % of farmers surveyed in 2007 but adoption fell somewhat to 67 % for soyabean, 57 % for CG7 groundnut and 43 % with pigeonpea among the wealthier farmers, while Bambara groundnut rose to 38 %. Fifty-two percent of poorer farmers reported adoption of CG7, 46 % soyabean, 35 % Bambara groundnut and 27 % pigeonpea in 2007. There was greater uptake by the wealthier farmers than those with fewer resources. Overall, although the legumes were promoted for maintenance of soil fertility, farmers were largely interested in and mainly adopted those legumes they considered most useful for food diversity and security, and with potential for market sale. Only a few wealthier farmers used mucuna and tephrosia among the green manure legumes. Improving the food value of vigorous and productive multi-purpose legumes, particularly mucuna, may help raise the farmers’ interest, with secondary benefits for soil fertility.     

Unambiguous one-molecule conductance measurements under ambient conditions

One of the challenging goals of molecular electronics is to wire exactly one molecule between two electrodes. This is generally nontrivial under ambient conditions. We describe a new and straightforward protocol for unambiguously isolating a single organic molecule on a metal surface and wiring it inside a nanojunction under ambient conditions. Our strategy employs C(60) terminal groups which act as molecular beacons allowing molecules to be visualized and individually targeted on a gold surface using an scanning tunneling microscope. After isolating one molecule, we then use the C(60) groups as alligator clips to wire it between the tip and surface. Once wired, we can monitor how the conductance of a purely one molecule junction evolves with time, stretch the molecule in the junction, observing characteristic current plateaus upon elongation, and also perform direct I-V spectroscopy. By characterizing and controlling the junction, we can draw stronger conclusions about the observed variation in molecular conductance than was previously possible.     

Qualitative egomotion

Due to the aperture problem, the only motion measurement in images, whose computation does not require any assumptions about the scene in view, is normal flow—the projection of image motion on the gradient direction. In this paper we show how a monocular observer can estimate its 3D motion relative to the scene by using normal flow measurements in a global and qualitative way. The problem is addressed through a search technique. By checking constraints imposed by 3D motion parameters on the normal flow field, the possible space of solutions is gradually reduced. In the four modules that comprise the solution, constraints of increasing restriction are considered, culminating in testing every single normal flow value for its consistency with a set of motion parameters. The fact that motion is rigid defines geometric relations between certain values of the normal flow field. The selected values form patterns in the image plane that are dependent on only some of the motion parameters. These patterns, which are determined by the signs of the normal flow values, are searched for in order to find the axes of translation and rotation. The third rotational component is computed from normal flow vectors that are only due to rotational motion. Finally, by looking at the complete data set, all solutions that cannot give rise to the given normal flow field are discarded from the solution space.Research supported in part by NSF (Grant IRI-90-57934), ONR (Contract N00014-93-1-0257) and ARPA (Order No. 8459).     

Disodium tetracarbonylferrate

Summary The replacement of the chlorine atoms of chloromethylated polystyrenes by carboxyl groups via reaction with disodium tetracarbonylferrate and subsequent treatment with an oxidizing agent is described.     

Novel dominant-negative prion protein mutants identified from a randomized library

Prion diseases are untreatable neurodegenerative disorders characterized by accumulation of PrP(Sc), an aggregated isoform of the cellular prion protein (PrP(C)). We generated a library of PrP variants with random mutations in the helix-3 domain and screened for dominant-negative mutants (DNMs) that would inhibit replication of prions (the Rocky Mountain Laboratory strain) in infected N2a cells. Two of the identified PrP mutants, Q167R and Q218K, were already known to counteract prion replication, thereby validating the effectiveness of this approach. In addition, novel DNMs were found efficiently to antagonize PrP(Sc) propagation in cells. In contrast to Q167R and Q218K, the newly identified DNMs S221P and Y217C resided on the cell surface at a substantially lower level, suggesting that robust cell surface display of DNM might not be a general prerequisite for efficient prion antagonism. The newly identified DNMs point to useful target-selective therapeutic tools for the treatment of prion diseases.     

Tuning the Cell Adhesion on Biofunctionalized Nanoporous Organic Frameworks

The ability to control the structure and surface chemistry of biomaterials on a molecular level is crucial for optimizing their performance. Here, a novel type of nanoporous organic framework that is suited for the fabrication of thin films is described. These surface‐grafted gels (SURGELs) are prepared and functionalized using two orthogonal, metal‐free click chemistries. The SURGELs are shown to be cytocompatible and to efficiently mediate adhesion of osteoblast‐like cells. This process can be further enhanced by surface modification. In addition, the use of light‐triggered reactions in combination with photomasks allows a patterned functionalization of the substrates. The potential to vary and exactly adjust the parameters within the SURGEL polymer network (including porosity and exact network topology on the nanometer scale as well as addressable functional groups) combined with the ability to functionalize their surfaces with any clickable biomolecule of choice in any desired pattern allow the targeted design of novel SURGEL‐based biomaterials for applications in nanomedicine, tissue engineering scaffolds, wound dressing,and medical implants.     

Effect of fiber length on processing and properties of extruded wood‐fiber/HDPE composites

Fiber length and distribution play important roles in the processing and mechanical performance of fiber‐based products such as paper and fiberboard. In the case of wood–plastic composites (WPC), the production of WPC with long fibers has been neglected, because they are difficult to handle with current production equipment. This study provides a better understanding of the effect of fiber length on WPC processing and properties. The objectives of this study were therefore to determine the role of fiber length in the formation process and property development of WPC. Three chemithermomechanical pulps (CTMP) with different lengths, distributions, and length‐to‐diameter ratios (L/D) were obtained by mechanical refining. Length, shape, and distribution were characterized using a fiber quality analyzer (FQA). The rheometer torque properties of high‐density polyethylene (HDPE) filled with the pulps at different loads were studied. Variations in fiber load and length distribution resulted in significant variations in melting properties and torque characteristics. Composites from the three length distributions were successfully processed using extrusion. Physical and mechanical properties of the obtained composites varied with both length distribution and additive type. Mechanical properties increased with increasing fiber length, whereas performance in water immersion tests decreased. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal Behavior of Isotactic Poly(propylene)/Maleated Poly(propylene) Blends

This paper analyzes the thermal and thermo‐oxidative degradation behavior, phase separation, melting, and crystallization of blends consisting of isotactic poly(propylene) (IPP) and poly(propylene) grafted with maleic anhydride (PP‐g‐MA). It has been established that, depending on the blend composition and crystallization/preparation procedure, the blends of IPP and PP‐g‐MA can either co‐crystallize or evidence phase separation. This conclusion has been attained by comparing the DSC results of crystallization under dynamic and isothermal conditions with X‐ray diffraction results. On the basis of the obtained results, the optimum mixing ratios have been established as 95–85 wt.‐% IPP/5–15 wt.‐% PP‐g‐MA. Thermo‐oxidative behavior has been studied by thermogravimetry and differential thermal analysis.

     

Trace metal stabilisation in a shooting range soil: mobility and phytotoxicity

Due to impact and abrasion of projectiles firing berms of shooting ranges frequently exhibit increased levels of bullet-borne contaminants. Stabilisation of backstop soils may be a promising pre- and post-use treatment to minimise leaching and bioavailability. This study focused on mobility and phytotoxicity of antimony, copper, and lead in stabilised berm material compared to an untreated control. Ferric (goethite, deferrisation sludge) and phosphatic amendments (diammonium phosphate, calcium dihydrogen phosphate) were used. Batch and column experiments demonstrated effective stabilisation of the contaminants by ferric amendments. Sequential extractions showed an increase of contaminant fractions associated with iron (hydr)oxides. Stabilisation was accompanied by a detoxification of seepage water compared to the control soil as shown by Duckweed growth inhibition. Contrasting the ferric additives, phosphatic amendments effectively stabilised lead but mobilised copper and antimony possibly due to a competitive displacement process. Thereby, benefits of lead stabilisation were completely overridden; this was underlined by increased phytotoxicity relative to the untreated soil. Overall, understanding stabilised soil as a multicomponent system is a prerequisite for the choice of appropriate amendments. This requires the synopsis of results from complementary test methods and a screening for a wide range of substances.     

A superabsorbent polymer-containing wound dressing efficiently sequesters MMPs and inhibits collagenase activity in vitro

Superabsorbent polymer (SAP)-containing wound dressings present a valuable and unique category of wound management products. An in vitro approach was used to assess the effects of a new SAP dressing in treatment of non-healing wounds. It was shown that the SAP dressing possesses a significant binding capacity for MMP-2 and MMP-9 in vitro (P < 0.001). The inclusion of the bound proteases was so strong that no MMP-2 and only marginal amounts of MMP-9 were released from the dressing samples in a subsequent elution step. In addition, the SAP dressing was able to take up collagenase and reduce its activity in vitro. However, collagenase was not completely inactivated upon binding and enzyme-mediated substrate turnover could be observed at the dressings. In conclusion, in vitro data confirm the positive effect of the SAP wound dressing observed in vivo. The findings suggest that it should be specifically useful for highly exuding wounds with an elevated proteolytic activity that needs to be reduced to support healing.