scholarly journals Tuning the Properties of Furandicarboxylic Acid-Based Polyesters with Copolymerization: A Review

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1209 ◽  
Author(s):  
Zoi Terzopoulou ◽  
Lazaros Papadopoulos ◽  
Alexandra Zamboulis ◽  
Dimitrios G. Papageorgiou ◽  
George Z. Papageorgiou ◽  
...  
Keyword(s):  
Present Review ◽  
New Class ◽  
Biobased Polymers ◽  
Sustainable Economy ◽  
Furandicarboxylic Acid

Polyesters based on 2,5-furandicarboxylic acid (FDCA) are a new class of biobased polymers with enormous interest, both from a scientific and industrial perspective. The commercialization of these polymers is imminent as the pressure for a sustainable economy grows, and extensive worldwide research currently takes place on developing cost-competitive, renewable plastics. The most prevalent method for imparting these polymers with new properties is copolymerization, as many studies have been published over the last few years. This present review aims to summarize the trends in the synthesis of FDCA-based copolymers and to investigate the effectiveness of this approach in transforming them to a more versatile class of materials that could potentially be appropriate for a number of high-end and conventional applications.

scholarly journals Mechanism of Allium Crops Bulb Enlargement in Response to Photoperiod: A Review

2020 ◽  
Vol 21 (4) ◽  
pp. 1325 ◽  
Author(s):  
Muhammad Jawaad Atif ◽  
Mohammad Abass Ahanger ◽  
Bakht Amin ◽  
Muhammad Imran Ghani ◽  
Muhammad Ali ◽  
...  
Keyword(s):  
Present Review ◽  
Flowering Locus T ◽  
Allium Species ◽  
Significant Development ◽  
New Class ◽  
Bulb Formation ◽  
Signaling Mechanisms ◽  
Photoperiodic Regulation ◽  
Underlying Mechanisms ◽  
Practical Level

The photoperiod marks a varied set of behaviors in plants, including bulbing. Bulbing is controlled by inner signals, which can be stimulated or subdued by the ecological environment. It had been broadly stated that phytohormones control the plant development, and they are considered to play a significant part in the bulb formation. The past decade has witnessed significant progress in understanding and advancement about the photoperiodic initiation of bulbing in plants. A noticeable query is to what degree the mechanisms discovered in bulb crops are also shared by other species and what other qualities are also dependent on photoperiod. The FLOWERING LOCUS T (FT) protein has a role in flowering; however, the FT genes were afterward reported to play further functions in other biological developments (e.g., bulbing). This is predominantly applicable in photoperiodic regulation, where the FT genes seem to have experienced significant development at the practical level and play a novel part in the switch of bulb formation in Alliums. The neofunctionalization of FT homologs in the photoperiodic environments detects these proteins as a new class of primary signaling mechanisms that control the growth and organogenesis in these agronomic-related species. In the present review, we report the underlying mechanisms regulating the photoperiodic-mediated bulb enlargement in Allium species. Therefore, the present review aims to systematically review the published literature on the bulbing mechanism of Allium crops in response to photoperiod. We also provide evidence showing that the bulbing transitions are controlled by phytohormones signaling and FT-like paralogues that respond to independent environmental cues (photoperiod), and we also show that an autorelay mechanism involving FT modulates the expression of the bulbing-control gene. Although a large number of studies have been conducted, several limitations and research gaps have been identified that need to be addressed in future studies.

Lipase-catalyzed synthesis of oligoesters of 2,5-furandicarboxylic acid with aliphatic diols

2015 ◽  
Vol 87 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Álvaro Cruz-Izquierdo ◽  
Lambertus A.M. van den Broek ◽  
Juan L. Serra ◽  
María J. Llama ◽  
Carmen G. Boeriu
Keyword(s):  
Ethylene Glycol ◽  
Chain Length ◽  
Immobilized Lipase ◽  
Product Inhibition ◽  
High Yield ◽  
Alkyl Chains ◽  
Biobased Polymers ◽  
Substrate Conversion ◽  
Furandicarboxylic Acid ◽  
Cyclic Compounds

Abstract2,5-Furandicarboxylic acid is a platform chemical for the production of biobased polymers and materials. This study reports the synthesis of furan oligoesters via polytransesterification of dimethyl furan-2,5-dicarboxylate and linear α, ω-aliphatic diols with chain length ranging from C2 to C12, using immobilized lipase B from Candida antarctica (Novozym 435) in dry organic solvents. Dimethyl furan-2,5-dicarboxylic acid (A) and 1,4-butanediol (B) were used as model substrates under different conditions producing a mixture of cyclic (CEOs) and linear (LEOs) ester oligomers up to decamers and dodecamers, respectively, with high yield. The size of the oligomers and distribution of the products is controlled by the initial concentration of substrates and temperature. While the shortest CEOs are the main cyclic compounds at 20 mM, the longest CEOs are formed at 175 mM. The chain length of the aliphatic diol co-monomers strongly influences the yield and the type of oligoesters formed. High substrate conversion of 90–95 % was obtained for C4–C12 diols, while in the case of ethylene glycol and 1,3-propanediol the conversion was moderate (i.e., 75 %). The product of the reaction between dimethyl furan-2,5-dicarboxylate and ethylene glycol (C2) and 1,3-propanediol (C3), respectively, consisted only of linear oligoesters. Longer oligoesters were obtained for alkyl chains higher than C4. The chain length and the abundance of oligoesters increases in the order: C2<C12<C10<C3<C8<C4 <C6. No substrate or product inhibition was observed in the production of furan-based oligoesters. The present biobased oligoesters are obtained via a green process and have potential application as macromonomers.

scholarly journals Platinum deposited on cerium coordination polymer for catalytic oxidation of hydroxymethylfurfural producing 2,5-furandicarboxylic acid

RSC Advances ◽  
2017 ◽  
Vol 7 (55) ◽  
pp. 34776-34782 ◽  
Author(s):  
Wei Gong ◽  
Kunkun Zheng ◽  
Peijun Ji
Keyword(s):  
Coordination Polymer ◽  
Catalytic Oxidation ◽  
Building Block ◽  
Value Added ◽  
Biobased Polymers ◽  
A Value ◽  
Furandicarboxylic Acid

2,5-Furandicarboxylic acid (FDCA) is a value added chemical that can be used as a polymer building block for the synthesis of biobased polymers.

scholarly journals Unveiling the Enzymatic Degradation Process of Biobased Thiophene Polyesters

2021 ◽  
Vol 9 ◽  
Author(s):  
Federico A. Bertolini ◽  
Michelina Soccio ◽  
Simone Weinberger ◽  
Giulia Guidotti ◽  
Massimo Gazzano ◽  
...  
Keyword(s):  
Degradation Process ◽  
Sem Analysis ◽  
Polymer Surfaces ◽  
Hydroxyl Groups ◽  
E Coli ◽  
New Class ◽  
The Past ◽  
Biobased Polymers ◽  
Thiophene Based Polymers ◽  
Hydrolysis Of

In the past 20 years, scientific research focused on the identification of valid alternatives to materials of fossil origin, in particular, related to biobased polymers. Recently, the efforts led to the synthesis of thiophene-based polymers (TBPs), a new class of polyesters based on 2,5-thiophenedicarboxylic acid (TPCA) that can be industrially produced using biomass-derived molecules. In this study, TBPs were synthesized using diols with different chain length (from C4 to C6) leading to poly(butylene 2,5-thiophenedicarboxylate) (PBTF), poly(pentamethylene 2,5-thiophenedicarboxylate) (PPeTF), and poly(hexamethylene 2,5-thiophenedicarboxylate) (PHTF), respectively, that were processed to thin films. To investigate enzymatic hydrolysis of these polymer films, cutinase 1 (Thc_cut1) and cutinase 2 (Thc_cut2) from Thermobifida cellulosilytica were recombinantly expressed in the host E. coli and purified. After 72 h of incubation at 65°C with 5 µM Thc_cut1, weight loss and HPLC analysis indicated 9, 100, and 80% degradation of PBTF, PPeTF, and PHTG with a concomitant release of 0.12, 2.70, and 0.67 mM of TPCA. The SEM analysis showed that tiny holes were formed on the surface of the films and after 72 h PPeTF was completely degraded. The LC-TOF/MS analysis indicated that Thc_cut2 in particular released various oligomers from the polymer during the reaction. In addition, the FTIR analysis showed the formation of novel acid and hydroxyl groups on the polymer surfaces. The results showed that the two used thermostable cutinases are promising biocatalysts for the environmentally friendly degradation of TPCA-based polyesters, in view of a possible sustainable recycling of plastic waste through resynthesis processes.

Imidazole: An emerging scaffold showing its therapeutic voyage to develop valuable molecular entities

2019 ◽  
Vol 11 ◽  
Author(s):  
Bhawna Chopra ◽  
Ashwani K. Dhingra ◽  
Deo Nandan Prasad
Keyword(s):  
Drug Development ◽  
Therapeutic Potential ◽  
Present Review ◽  
Evidence Based ◽  
Pharmacological Agents ◽  
New Class ◽  
Heterocyclic Molecules ◽  
Biological Potential ◽  
New Drug Development ◽  
Heterocyclic Moiety

Objective: Imidazole is a heterocyclic moiety having immense biological importance. Since from ancient years, imidazole nucleus was found to be promising moiety in field of chemistry. Preliminaryin vitroand in vivostudies have provided valuable scientific evidencefor its use. Subsequently, imidazole constitutes for new class of compounds for new drug development as presence of this nucleus in diverse therapeutic categories viz; antimicrobial, anti-inflammatory, anticancer, immunomodulator, antiviral etchas made it an interesting moiety for design and development of new pharmacological agents. Thus this review aims to summarize the reported molecular entities which were synthesized by using conventional as well as microwave processes, chemistry and biological potential of imidazole containing heterocyclic molecules while identifying potential areas of further research of imidazole. Key findings: The review comprises literature pertaining to the evidence based pharmacological or therapeutic potential of imidazole from may many years using published articles and worldwide databases. Various pharmacological experiments using different models exclusively proven the potential of imidazole. Summary: Thus, focusing on discovery and development of new imidazole nucleus based molecules at a faster rate; there is a need to check out the previous information available in market in the field of medicinal chemistry. So the present review aims ornately pronounced the therapeutic worth of imidazole and its analogs.

scholarly journals A Review on Environmentally-safe Corrosion deterrence of Metals in Various Media

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
R. Vasantha Jothi ◽  
R. Saratha ◽  
S. V. Priya
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibitors ◽  
Inhibition Efficiency ◽  
Present Review ◽  
Plant Materials ◽  
Industrial Activities ◽  
New Class ◽  
Mineral Acids ◽  
Environmentally Safe ◽  
Highly Virulent

<div><p><em>The present review gives a brief application of environmentally – safe corrosion inhibitors for various metals like aluminum, copper, mild steel, and zinc. Due to the enormous increase of industrial activities, a large amount of mineral acids are consumed. Therefore more number of metals gets corroded. These problems can be solved by using corrosion deterence. Although many chemical deterence are available most of them are highly virulent. So there is a need to explore a new class of corrosion inhibitors with good inhibition efficiency and that are environmentally - safe. Consequently, it can be achieved by using plant materials as corrosion inhibitors which are non-toxic, easily available and biodegradable.</em></p></div>

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

The microtubule associated protein (MAP) tau forms a new class of triple-stranded left-hand helical fibrous protein polymer

1992 ◽  
Vol 50 (1) ◽  
pp. 540-541
Author(s):  
G. C. Ruben ◽  
K. Iqbal ◽  
I. Grundke-Iqbal ◽  
H. Wisniewski ◽  
T. L. Ciardelli ◽  
...  
Keyword(s):  
Axial Ratio ◽  
Normal Structure ◽  
Paired Helical Filaments ◽  
Left Hand ◽  
New Class ◽  
Protein Polymer ◽  
Fibrous Protein ◽  
Protein Map ◽  
Neurotransmitter Transport ◽  
Alzheimer Neurofibrillary Tangles

In neurons, the microtubule associated protein, tau, is found in the axons. Tau stabilizes the microtubules required for neurotransmitter transport to the axonal terminal. Since tau has been found in both Alzheimer neurofibrillary tangles (NFT) and in paired helical filaments (PHF), the study of tau's normal structure had to preceed TEM studies of NFT and PHF. The structure of tau was first studied by ultracentrifugation. This work suggested that it was a rod shaped molecule with an axial ratio of 20:1. More recently, paraciystals of phosphorylated and nonphosphoiylated tau have been reported. Phosphorylated tau was 90-95 nm in length and 3-6 nm in diameter where as nonphosphorylated tau was 69-75 nm in length. A shorter length of 30 nm was reported for undamaged tau indicating that it is an extremely flexible molecule. Tau was also studied in relation to microtubules, and its length was found to be 56.1±14.1 nm.

Study of segregation in La1.8Sr0.2CuO4 superconductor by STEM-EDS microanalysis

1987 ◽  
Vol 45 ◽  
pp. 54-55
Author(s):  
T. F. Kelly ◽  
P. J. Lee ◽  
E. E. Hellstrom ◽  
D. C. Larbalestier
Keyword(s):  
Rare Earth ◽  
High Field ◽  
Transport Current ◽  
Total Thickness ◽  
New Class ◽  
Ceramic Superconductors ◽  
Current Densities ◽  
Group Ii ◽  
Eds Microanalysis

Recently there has been much excitement over a new class of high Tc (>30 K) ceramic superconductors of the form A1-xBxCuO4-x, where A is a rare earth and B is from Group II. Unfortunately these materials have only been able to support small transport current densities 1-10 A/cm2. It is very desirable to increase these values by 2 to 3 orders of magnitude for useful high field applications. The reason for these small transport currents is as yet unknown. Evidence has, however, been presented for superconducting clusters on a 50-100 nm scale and on a 1-3 μm scale. We therefore planned a detailed TEM and STEM microanalysis study in order to see whether any evidence for the clusters could be seen.A La1.8Sr0.2Cu04 pellet was cut into 1 mm thick slices from which 3 mm discs were cut. The discs were subsequently mechanically ground to 100 μm total thickness and dimpled to 20 μm thickness at the center.

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