scholarly journals A Review of Research Directions and Research Methods of Farmland Weeds

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Shujuan Li ◽  
Guoqin Huang
Keyword(s):  
Research Methods ◽  
Weed Control ◽  
High Efficiency ◽  
Research Work ◽  
Reference Value ◽  
Seed Banks ◽  
High Yield ◽  
Weed Seed ◽  
Research Directions ◽  
Weed Communities

Farmland weeds are an important part of farmland ecosystems. Research on farmland weeds is one of the major research fields in agricultural ecology. It is of great significance for achieving high yield, high quality and high efficiency in agriculture. In recent years, research on farmland weeds has focused on investigation of weed communities, research on weed seed banks, and research on weed control. These three research directions complement each other. Among them, the investigation work of weed communities and the research of weed seed banks are helpful for us to grasp the occurrence of farmland weeds more accurately and provide references for the control of farmland weeds. This article summarizes the research directions of farmland weeds in recent years (weed community investigation, weed seed bank, weed control) and the research methods used, provide reference value for the follow-up research work of farmland weeds, and provide theoretical support for promoting the development of rural ecological industry and building beautiful villages.

Management Filters and Species Traits: Weed Community Assembly in Long-Term Organic and Conventional Systems

Weed Science ◽  
2010 ◽  
Vol 58 (3) ◽  
pp. 265-277 ◽  
Author(s):  
Matthew R. Ryan ◽  
Richard G. Smith ◽  
Steven B. Mirsky ◽  
David A. Mortensen ◽  
Rita Seidel
Keyword(s):  
Weed Control ◽  
Seed Bank ◽  
Community Assembly ◽  
Species Traits ◽  
Seed Banks ◽  
Management Systems ◽  
Conventional System ◽  
Weed Seed ◽  
Organic Systems ◽  
Weed Communities

Community assembly theory provides a useful framework to assess the response of weed communities to agricultural management systems and to improve the predictive power of weed science. Under this framework, weed community assembly is constrained by abiotic and biotic “filters” that act on species traits to determine community composition. We used an assembly approach to investigate the response of weed seed banks to 25 yr of management-related filtering in three different row-crop management systems in southeastern Pennsylvania: organic manure-based, organic legume-based, and conventional. Weed seed banks were sampled in April of 2005 and 2006 and quantified by direct germination in a greenhouse. We also assessed the filtering effects of weed management practices and relationships between assembled seed bank and emergent weed communities by allowing or excluding weed control practices within each management system and measuring emergent weed community response. Germinable weed seed bank densities and species richness in the final year of the study were over 40% and 15% higher, respectively, in the organic systems relative to the conventional system. Seed bank community structure in the organic systems was different from the conventional system, and the relationships between assembled seed banks and the emergent flora varied. Primary tillage, weed control, timing of planting, and fertility management appeared to be the main filters that differentiated weed seed banks in the three systems. Weed life history, emergence periodicity, seed size, and responsiveness to soil fertility and hydrology appeared to be the most important functional traits determining how weed species responded to management-related filters. Our results suggest that management systems can exert strong filtering effects that can persist over relatively long (greater than one growing season) time scales. Legacy effects of community-level filtering might be more important than previously assumed, and should be incorporated into predictive models of weed community assembly.

Weed Seed Banks in Established Strawberry Fields

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 459f-460
Author(s):  
Faye Propsom ◽  
Emily Hoover
Keyword(s):  
Organic Matter ◽  
Weed Control ◽  
Seed Bank ◽  
Cultural Practices ◽  
Seed Banks ◽  
Soil Samples ◽  
Soil Types ◽  
Twin Cities ◽  
Weed Seed ◽  
Metro Area

Weed control in strawberries, either in a new planting or one that is established, is a major source of problems for growers in Minnesota. To control weeds, growers need to know which weeds are a problem, which weeds are deleterious, and which weeds have the potential to become a problem. Weeds present, soil type, and weed seed bank information are needed in order to predict potential weed problems. With different weed control practices applied between and within the rows, we assumed weed seed bank populations would vary. In addition, we were interested in seeing if the seed banks differed between soil types and individual farmer's cultural practices. Soil samples were collected from 13 commercial strawberry fields located around the Twin Cities metro area. In 1996, samples were taken after renovation and before mulch was applied. In 1997, they were taken after mulch was removed and prior to renovation. The soil samples for each date, treatment, and farm were dried, and organic matter was separated from inorganic. The weed seeds were removed from the remaining organic matter, identified and counted. Soil types and cultural practices were used to compare the differences among the farms.

A Comparison of Threshold Strategies in Tomatoes and Soybean

2008 ◽  
Vol 22 (4) ◽  
pp. 729-735 ◽  
Author(s):  
Carlos D. Mayén ◽  
Kevin D. Gibson ◽  
Stephen C. Weller
Keyword(s):  
Weed Control ◽  
Seed Bank ◽  
Crop Yields ◽  
Control Strategies ◽  
Seed Banks ◽  
Weed Seed ◽  
Tomato Seed ◽  
Giant Foxtail ◽  
The Difference

Weed control strategies based on conserving crop yields rather than preventing weed seed production may result in increased weed densities and management costs over the long-term, particularly in less competitive crops such as tomatoes. The effect of crop, tillage, and duration of weed control on weed seed bank size and composition was examined from spring 2001 to spring 2003 near Lafayette, IN. Main plots in 2001 and 2002 contained soybean or tomato planted in rotation (soybean-tomato, tomato-soybean). Subplots were managed with either conventional or no-till practices. Sub-subplots contrasted threshold strategies in which weeds were either controlled for four to six weeks (period threshold, PT) or throughout the growing season (no-seed-threshold, NST). Seed banks were sampled annually in the spring. Emergent weeds were counted` at four and twelve weeks after planting (WAP) in 2001 and 2002. Weed seed banks did not significantly change in the NST plots in any year. However, seed bank densities increased substantially following tomatoes in PT plots. In contrast, weed seed bank densities decreased following soybeans in PT plots. The difference in seed banks and emergent weeds between soybean and tomatoes could be attributed primarily to greater suppression of giant foxtail by the soybean canopy. Giant foxtail control was greater in PT soybeans than in PT tomatoes in both years and giant foxtail comprised most of the PT tomato seed bank in 2002 and 2003. Tillage did not affect weed seed banks in any year. This study highlights the need to control later emerging weeds in tomatoes to prevent large increases in the weed seed bank.

Piezoelectric β-polymorph formation of new textiles by surface modification with coating process based on interfacial interaction on the conformational variation of poly (vinylidene fluoride) (PVDF) chains

2020 ◽  
Vol 91 (3) ◽  
pp. 31301
Author(s):  
Nabil Chakhchaoui ◽  
Rida Farhan ◽  
Meriem Boutaldat ◽  
Marwane Rouway ◽  
Adil Eddiai ◽  
...  
Keyword(s):  
High Efficiency ◽  
Vinylidene Fluoride ◽  
Research Work ◽  
Research Area ◽  
Interfacial Interaction ◽  
Tetraethyl Orthosilicate ◽  
Poly Vinylidene Fluoride ◽  
Carbon Nanofillers ◽  
The Impact ◽  
Advanced Applications

Novel textiles have received a lot of attention from researchers in the last decade due to some of their unique features. The introduction of intelligent materials into textile structures offers an opportunity to develop multifunctional textiles, such as sensing, reacting, conducting electricity and performing energy conversion operations. In this research work nanocomposite-based highly piezoelectric and electroactive β-phase new textile has been developed using the pad-dry-cure method. The deposition of poly (vinylidene fluoride) (PVDF) − carbon nanofillers (CNF) − tetraethyl orthosilicate (TEOS), Si(OCH2CH3)4 was acquired on a treated textile substrate using coating technique followed by evaporation to transform the passive (non-functional) textile into a dynamic textile with an enhanced piezoelectric β-phase. The aim of the study is the investigation of the impact the coating of textile via piezoelectric nanocomposites based PVDF-CNF (by optimizing piezoelectric crystalline phase). The chemical composition of CT/PVDF-CNC-TEOS textile was detected by qualitative elemental analysis (SEM/EDX). The added of 0.5% of CNF during the process provides material textiles with a piezoelectric β-phase of up to 50% has been measured by FTIR experiments. These results indicated that CNF has high efficiency in transforming the phase α introduced in the unloaded PVDF, to the β-phase in the case of nanocomposites. Consequently, this fabricated new textile exhibits glorious piezoelectric β-phase even with relatively low coating content of PVDF-CNF-TEOS. The study demonstrates that the pad-dry-cure method can potentially be used for the development of piezoelectric nanocomposite-coated wearable new textiles for sensors and energy harvesting applications. We believe that our study may inspire the research area for future advanced applications.

scholarly journals Near quantitative synthesis of urea macrocycles enabled by bulky N-substituent

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yingfeng Yang ◽  
Hanze Ying ◽  
Zhixia Li ◽  
Jiang Wang ◽  
Yingying Chen ◽  
...  
Keyword(s):  
High Efficiency ◽  
Molecular Structures ◽  
High Yield ◽  
Kinetic Control ◽  
High Concentration ◽  
Weak Association ◽  
Quantitative Synthesis ◽  
Thermodynamic Stabilization ◽  
Discrete Structures ◽  
Very High

AbstractMacrocycles are unique molecular structures extensively used in the design of catalysts, therapeutics and supramolecular assemblies. Among all reactions reported to date, systems that can produce macrocycles in high yield under high reaction concentrations are rare. Here we report the use of dynamic hindered urea bond (HUB) for the construction of urea macrocycles with very high efficiency. Mixing of equal molar diisocyanate and hindered diamine leads to formation of macrocycles with discrete structures in nearly quantitative yields under high concentration of reactants. The bulky N-tert-butyl plays key roles to facilitate the formation of macrocycles, providing not only the kinetic control due to the formation of the cyclization-promoting cis C = O/tert-butyl conformation, but also possibly the thermodynamic stabilization of macrocycles with weak association interactions. The bulky N-tert-butyl can be readily removed by acid to eliminate the dynamicity of HUB and stabilize the macrocycle structures.

scholarly journals A Brief Review on Solvent-Free Synthesis of Zeolites

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 788
Author(s):  
Jinlin Mei ◽  
Aijun Duan ◽  
Xilong Wang
Keyword(s):  
High Efficiency ◽  
Raw Materials ◽  
Solvent Free ◽  
High Yield ◽  
Control Synthesis ◽  
Mechanical Mixing ◽  
Synthesis Mechanism ◽  
Wastewater Pollution ◽  
Low Efficiency ◽  
Solvent Free Synthesis

The traditional hydrothermal method to prepare zeolite will inevitably use a large amount of water as a solvent, which will lead to higher autogenous pressure, low efficiency, and wastewater pollution. The solvent-free method can be used to synthesize various types of zeolites by mechanical mixing, grinding, and heating of solid raw materials, which exhibits the apparent advantages of high yield, low pollution, and high efficiency. This review mainly introduces the development process of solvent-free synthesis, preparation of hierarchical zeolite, morphology control, synthesis mechanism and applications of solvent-free methods. It can be believed that solvent-free methods will become a research focus and have enormous industrial application potential.

scholarly journals Iodine reduction for reproducible and high-performance perovskite solar cells and modules

2021 ◽  
Vol 7 (10) ◽  
pp. eabe8130
Author(s):  
Shangshang Chen ◽  
Xun Xiao ◽  
Hangyu Gu ◽  
Jinsong Huang
Keyword(s):  
Solar Cells ◽  
High Performance ◽  
High Efficiency ◽  
Electronic Materials ◽  
Substantial Reduction ◽  
Perovskite Solar Cells ◽  
High Yield ◽  
Operation Conditions ◽  
Record Value ◽  
Precursor Powders

Perovskite-based electronic materials and devices such as perovskite solar cells (PSCs) have notoriously bad reproducibility, which greatly impedes both fundamental understanding of their intrinsic properties and real-world applications. Here, we report that organic iodide perovskite precursors can be oxidized to I2 even for carefully sealed precursor powders or solutions, which markedly deteriorates the performance and reproducibility of PSCs. Adding benzylhydrazine hydrochloride (BHC) as a reductant into degraded precursor solutions can effectively reduce the detrimental I2 back to I−, accompanied by a substantial reduction of I3−-induced charge traps in the films. BHC residuals in perovskite films further stabilize the PSCs under operation conditions. BHC improves the stabilized efficiency of the blade-coated p-i-n structure PSCs to a record value of 23.2% (22.62 ± 0.40% certified by National Renewable Energy Laboratory), and the high-efficiency devices have a very high yield. A stabilized aperture efficiency of 18.2% is also achieved on a 35.8-cm2 mini-module.

scholarly journals Friction-Induced Recycling Process for User-Specific Semi-Finished Product Production

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 663
Author(s):  
Thomas Borgert ◽  
Werner Homberg
Keyword(s):  
High Efficiency ◽  
Research Work ◽  
Hot Extrusion ◽  
Extrusion Process ◽  
Efficient Production ◽  
Secondary Aluminum ◽  
Shape Accuracy ◽  
Aluminum Chips ◽  
Spinning Process ◽  
Complex Parts

Modern forming processes often allow today the efficient production of complex parts. In order to increase the sustainability of forming processes it would be favorable if the forming of workpieces becomes possible using production waste. At the Chair of Forming and Machining Technology of the Paderborn University (LUF) research is presently conducted with the overall goal to produce workpieces directly from secondary aluminum (e.g., powder and chips). Therefore, friction-based forming processes like friction spinning (or cognate processes) are used due to their high efficiency. As a pre-step, the production of semi-finished parts was the subject of accorded research work at the LUF. Therefore, a friction-based hot extrusion process was used for the full recycling or rework of aluminum chips into profiles. Investigations of the recycled semi-finished products show that they are comparable to conventionally produced semi-finished products in terms of dimensional stability and shape accuracy. An analysis of the mechanical properties of hardness and tensile strength shows that a final product with good and homogeneously distributed properties can be produced. Furthermore, significant correlations to the friction spinning process could be found that are useful for the above-mentioned direct part production from secondary aluminum.

Design of a Retrovirus-Derived Vector for Expression and Transduction of Exogenous Genes in Mammalian Cells

1983 ◽  
Vol 3 (6) ◽  
pp. 1123-1132
Author(s):  
Archibald S. Perkins ◽  
Paul T. Kirschmeier ◽  
Sebastiano Gattoni-Celli ◽  
I. Bernard Weinstein
Keyword(s):  
Mammalian Cells ◽  
High Efficiency ◽  
Leukemia Virus ◽  
Restriction Enzymes ◽  
Virus Genome ◽  
Opposite Polarity ◽  
High Yield ◽  
Animal Cells ◽  
Murine Sarcoma Virus ◽  
Sarcoma Virus

We have developed a transfection vector for animal cells that contains long terminal repeat (LTR) sequences to promote expression. Plasmid p101/101, a derivative of plasmid pBR322 containing the complete Moloney murine sarcoma virus genome, was cut with restriction enzymes and religated so that both the 5′ and 3′ LTRs were retained and all but about 700 base pairs of the intervening viral sequences were removed. To test this vector, the Escherichia coli gene gpt was cloned into a unique Pst I site, between the two LTRs, with guanine and cytosine tailing, a method that can be generalized for insertion of any DNA segment into this vector. When DNA from recombinant plasmids in which the gpt gene was inserted in the same transcriptional polarity as the LTR sequences was transfected onto murine or rat fibroblast cultures, we obtained a high yield of Gpt + colonies. However, plasmid constructs with the gpt gene in the opposite polarity were virtually devoid of activity. With gpt in the proper orientation, restriction enzyme cuts within the LTRs or between the 5′ LTR and the gpt gene reduced transfection by more than 98%, whereas a cut between the gpt gene and the 3′ LTR gave an 80% reduction in activity. Thus, both 5′ and 3′ LTR sequences are essential for optimal gpt expression, although the 5′ LTR appears to play a more important role. When the LTR- gpt plasmid was transfected onto murine leukemia virus-infected mouse fibroblasts, we obtained evidence that RNA copies became pseudotyped into viral particles which could transfer the Gpt + phenotype into rodent cells with extremely high efficiency. This vector should prove useful for high-efficiency transduction of a variety of genes in mammalian cells.

High yield and greener C–H difluoromethylation reactions using copper iodide nanoparticles/boron nitride nanosheets as a versatile and recyclable heterogeneous catalyst

2021 ◽  
Author(s):  
Udayakumar Veerabagu ◽  
Gowsika Jaikumar ◽  
Fushen Lu ◽  
Franck Quero
Keyword(s):  
Boron Nitride ◽  
Heterogeneous Catalyst ◽  
High Efficiency ◽  
High Yield ◽  
Copper Iodide ◽  
Boron Nitride Nanosheets ◽  
Greener Synthesis ◽  
High Yields ◽  
Recyclable Heterogeneous Catalyst

The 3 wt% CuI/BNNS catalyst exhibited high efficiency for C–H difluoromethylation reactions and enabled greener synthesis at high yields using cyrene as a solvent. Furthermore, the catalyst could be easily recovered and recycled for at least five cycles.

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