52 research outputs found
Polyvinylidene Fluoride Aerogels with Tailorable Crystalline Phase Composition
In this work, polyvinylidene fluoride (PVDF) aerogels with a tailorable phase composition
were prepared by following the crystallization-induced gelation principle. A series of PVDF wet gels
(5 to 12 wt.%) were prepared from either PVDFâDMF solutions or a mixture of DMF and ethanol
as non-solvent. The effects of the non-solvent concentration on the crystalline composition of the
PVDF aerogels were thoroughly investigated. It was found that the nucleating role of ethanol can be
adjusted to produce low-density PVDF aerogels, whereas the changes in composition by the addition
of small amounts of water to the solution promote the stabilization of the valuable ÎČ and Îł phases.
These phases of the aerogels were monitored by FTIR and Raman spectroscopies. Furthermore, the
crystallization process was followed by in-time and in situ ATRâFTIR spectroscopy. The obtained
aerogels displayed specific surface areas > 150 m2 gâ1, with variable particle morphologies that are
dependent on the non-solvent composition, as observed by using SEM and Synchrotron Radiation
Computed micro-Tomography (SR-ÎŒC
The legume pod borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae), an important insect pest of cowpea: a review emphasizing West Africa
The legume pod borer Maruca vitrata Fabricius (Lepidoptera: Crambidae) is a pantropical insect pest of legumes. In West Africa M. vitrata is the most devastating insect pest of cowpea, a food crop providing much-needed, inexpensive protein to farmers and consumers. Various approaches to controlling this pest have been tried, including cultural management, host plant resistance and use of synthetic and botanical pesticides, all with limited success. In this review we present information on the distribution, morphology, molecular characteristics, behavior and host plants of M. vitrata. We give especial attention to innovative management tactics being developed for West Africa, including genetically engineered Bt cowpea, new biopesticides and use of exotic parasitoids. We discuss research needs for enhancing integrated pest management (IPM) for M. vitrata in Africa
An epidemiological model for prediction of endometrial cancer risk in Europe
Endometrial cancer (EC) is the fourth most frequent cancer in women in Europe, and as its incidence is increasing, prevention strategies gain further pertinence. Risk prediction models can be a useful tool for identifying women likely to benefit from targeted prevention measures. On the basis of data from 201,811 women (mostly aged 30â65 years) including 855 incident EC cases from eight countries in the European Prospective Investigation into Cancer and Nutrition cohort, a model to predict EC was developed. A step-wise model selection process was used to select confirmed predictive epidemiologic risk factors. Piece-wise constant hazard rates in 5-year age-intervals were estimated in a cause-specific competing risks model, five-fold-cross-validation was applied for internal validation. Risk factors included in the risk prediction model were body-mass index (BMI), menopausal status, age at menarche and at menopause, oral contraceptive use, overall and by different BMI categories and overall duration of use, parity, age at first full-term pregnancy, duration of menopausal hormone therapy and smoking status (specific for pre, peri- and post-menopausal women). These variables improved the discriminating capacity to predict risk over 5 years from 71 % for a model based on age alone to 77 % (overall C statistic), and the model was well-calibrated (ratio of expected to observed cases = 0.99). Our model could be used for the identification of women at increased risk of EC in Western Europe. To achieve an EC-risk model with general validity, a large-scale cohort-consortium approach would be needed to assess and adjust for population variation
Bt Eggplant Project in Bangladesh: History, Present Status, and Future Direction
The purpose of this article is to provide information on the history, accomplishments, and future direction of the Bt brinjal (eggplant) program in Bangladesh, formerly under the Agricultural Biotechnology Support Project II, now the South Asia Eggplant Improvement Partnership (SAEIP). The India-based Maharashtra Hybrid Seed Company (Mahyco) developed an eggplant expressing Cry1Ac (EE-1) for control of the eggplant fruit and shoot borer (EFSB). In a partnership among Mahyco, USAID, Sathguru Management Consultants and Cornell University EE-1 was provided to the Bangladesh Agricultural Research Institute (BARI) who bred it into local varieties. After regulatory approval, four varieties were distributed to 20 farmers who harvested Bt brinjal in 2014. Adoption in subsequent years has increased rapidly so that, in 2018, 27,012 farmers used this technology. This article provides background information on the process leading up to current adoption levels, the level of control of EFSB achieved and the economic benefits of Bt brinjal. Efforts on stewardship, farmer training and communication are discussed. In order to ensure the long-term future of the partnership, we discuss the need to enhance involvement of the private sector in the production and stewardship of Bt eggplant. Bt brinjal is the first genetically engineered crop to be commercially released in Bangladesh, and other GE crops are in the pipeline. Hence, success of the Bt brinjal partnership is likely to affect the future of other GE crops in Bangladesh, as well as other parts of the world where biotechnology is needed for food security and environmental safety
Distribution and diversity of alternate hosts of Maruca vitrata Fabricius in three West African countries
The evolution of resistance to the Bacillus thuringiensis (Bt) toxins by insect pests is a major threat to Bt technology.
However, the rate of resistance can be slowed with appropriate integrated insect resistance management (IRM) strategies.
Surveys were conducted to identify alternate host species for Maruca vitrata (commonly called the legume pod
borer or Maruca) that could serve as refuges for Pod-Borer Resistant (PBR) cowpea in three West African countries (Ghana,
Nigeria, and Burkina Faso). Survey sites included 25 in northern Ghana, 44 in northern Nigeria, and 52 in north-central and
southwestern Burkina Faso. Alternate hosts of Maruca identified from plant species belonging to the Fabaceae family that
showed signs of Maruca damage on cowpea tissues were collected and dissected. Larvae that were found during these
dissections were reared to adult moths in the laboratory then identified to species. The alternate host plants including species
of Crotolaria, Sesbania, Tephrosia, and Vigna were the most frequently encountered among sites and locations. Flowering
and podding of these plants overlapped with flowering and podding of the nearby (~200 m) cowpea crop. Abundance of
these wild hosts and overlapping flowering patterns with the cowpea crop in most locations have the potential to sustain ample
numbers of Bt susceptible Maruca that will mate with possible resistant Maruca and deter resistance development. Further
quantitative studies, however, are required from each location to determine if actual Maruca production from alternate hosts
is sufficient for a PBR IRM strategy. If verified, this approach would be compatible with the high dose/refuge IRM strategy
that includes alternate hosts and non-Bt crops as refuges
Assessment of risk of insect-resistant transgenic crops to nontarget arthropods
An international initiative is developing a scientifically rigorous approach to evaluate the potential risks to nontarget arthropods (NTAs) posed by insect-resistant, genetically modified (IRGM) crops. It adapts the tiered approach to risk assessment that is used internationally within regulatory toxicology and environmental sciences. The approach focuses on the formulation and testing of clearly stated risk hypotheses, making maximum use of available data and using formal decision guidelines to progress between testing stages (or tiers). It is intended to provide guidance to regulatory agencies that are currently developing their own NTA risk assessment guidelines for IRGM crops and to help harmonize regulatory requirements between different countries and different regions of the world
Efficacy of a cry1Ab Gene for Control of Maruca vitrata (Lepidoptera: Crambidae) in Cowpea (Fabales: Fabaceae)
Cowpea [Vigna unguiculata (L) Walp.] is an important staple legume in the diet of many households in
sub-Saharan Africa. Its production, however, is negatively impacted by many insect pests including bean pod
borer, Maruca vitrata F., which can cause 20â80% yield loss. Several genetically engineered cowpea events
that contain a cry1Ab gene from Bacillus thuringiensis (Bt) for resistance against M. vitrata were evaluated in
Nigeria, Burkina Faso, and Ghana (West Africa), where cowpea is commonly grown. As part of the regulatory
safety package, these efficacy data were developed and evaluated by in-country scientists. The Bt-cowpea lines
were planted in confined field trials under Insect-proof netting and artificially infested with up to 500 M. vitrata
larvae per plant during bud formation and flowering periods. Bt-cowpea lines provided nearly complete pod
and seed protection and in most cases resulted in significantly increased seed yield over non-Bt control lines.
An integrated pest management strategy that includes use of Bt-cowpea augmented with minimal insecticide
treatment for protection against other insects is recommended to control pod borer to enhance cowpea
production. The insect resistance management plan is based on the high-dose refuge strategy where non-Btcowpea
and natural refuges are expected to provide M. vitrata susceptible to Cry1Ab protein. In addition, there
will be a limited release of this product until a two-toxin cowpea pyramid is released. Other than South African
genetically engineered crops, Bt-cowpea is the first genetically engineered food crop developed by the public
sector and approved for release in sub-Saharan Africa
Recommendations for the design of laboratory studies on non-target arthropods for risk assessment of genetically engineered plants
This paper provides recommendations on experimental design for early-tier laboratory studies used in risk assessments to evaluate potential adverse impacts of arthropod-resistant genetically engineered (GE) plants on non-target arthropods (NTAs). While we rely heavily on the currently used proteins from Bacillus thuringiensis (Bt) in this discussion, the concepts apply to other arthropod-active proteins. A risk may exist if the newly acquired trait of the GE plant has adverse effects on NTAs when they are exposed to the arthropod-active protein. Typically, the risk assessment follows a tiered approach that starts with laboratory studies under worst-case exposure conditions; such studies have a high ability to detect adverse effects on non-target species. Clear guidance on how such data are produced in laboratory studies assists the product developers and risk assessors. The studies should be reproducible and test clearly defined risk hypotheses. These properties contribute to the robustness of, and confidence in, environmental risk assessments for GE plants. Data from NTA studies, collected during the analysis phase of an environmental risk assessment, are critical to the outcome of the assessment and ultimately the decision taken by regulatory authorities on the release of a GE plant. Confidence in the results of early-tier laboratory studies is a precondition for the acceptance of data across regulatory jurisdictions and should encourage agencies to share useful information and thus avoid redundant testing
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