scholarly journals Strategies for Lignin Pretreatment, Decomposition and Modification: A Review

2020 ◽  
Vol 9 (1) ◽  
pp. 01-20
Author(s):  
Leta Deressa Tolesa ◽  
Ming-Jer Lee
Keyword(s):  
Fossil Fuels ◽  
Environmental Concern ◽  
Renewable Resource ◽  
Extraction Methods ◽  
Molecular Structures ◽  
Raw Material ◽  
Gaseous Emissions ◽  
Large Molecules ◽  
Climate Stability

The dependency of chemical industry on nonrenewable sources of energy such as petroleum based carbon feedstock is rising dramatically day to day. Nonetheless, global warming caused by greenhouse gas emissions threatens the environment balance and the climate stability. Accordingly, it is necessary to find a renewable resource to decrease the environmental concern, specifically gaseous emissions from fossil fuels and to provide the energy stock. Outstanding to the significance of lignocellulosic biomass as most remedy to the current environmental issues and substituent of nonrenewable source of energy, this review affords understandings about the role of lignin as polymer and raw material for large molecules. In this review article, types of lignin with their extraction methods, fractionation technology to valuable chemicals, modification of the macromolecules to other polymers with tunableproperties, and an extensive range of applications are discussed widely. The major valuable chemicals produced from lignin via chemical depolymerization are also summarized and illustrated with their molecular structures.

scholarly journals Can changes in forest management contribute to the reduction of CO2 in the atmosphere? Literature review, discussion and Polish example

2019 ◽  
Vol 61 (4) ◽  
pp. 299-318
Author(s):  
Krzysztof Adamowicz ◽  
Ljiljana Keca
Keyword(s):  
Fossil Fuels ◽  
Financial Incentive ◽  
Treated Wood ◽  
Reduction Process ◽  
Raw Material ◽  
Scientific Publications ◽  
Organic Carbon Storage ◽  
The Impact ◽  
Positive Effect

Abstract Both COP21 and COP22 stressed the role of forests in climate protection as a natural CO2 sink. With this in mind, the study reviewed some literature findings related to afforestation, stand level management, forest soils, peatland management and storage yards to increase the amount of CO2 absorbed by the forest ecosystem. It was shown that some of the assumptions, for example, afforestation or improved water relations in soils, may contribute to reduced CO2 levels in the atmosphere. Our research was of a review nature and consisted in seeking information in various scientific publications. For a better interpretation of the results, we have divided our research into several parts. In the first part, we analysed the importance of deforestation and afforestation in the context of CO2 accumulation. We discussed the results of research on these issues giving specific examples. We have analysed the possibility of afforestation of new land. Using the example of Poland, we have indicated problems related to this issue. We have analysed the possibility of afforestation of new land. On the example of Poland, we have indicated problems related to this problem. We have come to the conclusion that in today’s Europe, the obstacle to such efforts is the lack of land that can be afforested and the financial incentive to abandon farming for forestry is too low. In the second part, we discussed the role of forest stands in the process of CO2 accumulation and reduction. We discussed breeding treatments that can be performed on racks. We noticed their importance in the CO2 reduction process. We noticed that when the density of forests increased, this has a positive effect on organic carbon storage. We presented and discussed examples of different rotation strategies in the context of their impact on CO2 accumulation. We analysed issues related to obtaining wood raw material and possible further storage of coal or its release into the atmosphere. We have recognized that proper forest soil management is important for CO2 accumulation. Therefore, another part of the research was devoted to the discussion on the role of soil in the process of CO2 accumulation. We discussed examples of using soil for forest and non-forest purposes, looking for the answer: how does this affect CO2 accumulation? In addition, we analysed the impact of soil moisture on processes related to CO2 storage. In our research, we critically treated wood storage as a method of reducing CO2. We also discussed the problem of treating wood as a source of bioenergy. We came to the conclusion that wood as an energy source can have a positive effect on CO2 reduction. The condition is, however, that energy produced from wood replaces energy from fossil fuels. Finally, we presented and discussed financial and legal issues related to CO2 reduction activities involving forests. We have found that attempts to commercialize CO2 emission reduction units for emissions generated in forests should be linked to the environmental responsibility of companies, and as such, should not be included in the current emissions’ trading policies. In the article, we also present a Polish proposal to run coal farms. We discuss their importance in the context of the issues discussed in this article.

Exchange Spin Coupling from Gaussian Process Regression

2020 ◽  
Author(s):  
Marc Philipp Bahlke ◽  
Natnael Mogos ◽  
Jonny Proppe ◽  
Carmen Herrmann
Keyword(s):  
Machine Learning ◽  
Gaussian Process ◽  
Gaussian Process Regression ◽  
Molecular Magnets ◽  
Molecular Structures ◽  
Spin Coupling ◽  
Structure Property ◽  
Data Set ◽  
Uncertainty Estimates

Heisenberg exchange spin coupling between metal centers is essential for describing and understanding the electronic structure of many molecular catalysts, metalloenzymes, and molecular magnets for potential application in information technology. We explore the machine-learnability of exchange spin coupling, which has not been studied yet. We employ Gaussian process regression since it can potentially deal with small training sets (as likely associated with the rather complex molecular structures required for exploring spin coupling) and since it provides uncertainty estimates (“error bars”) along with predicted values. We compare a range of descriptors and kernels for 257 small dicopper complexes and find that a simple descriptor based on chemical intuition, consisting only of copper-bridge angles and copper-copper distances, clearly outperforms several more sophisticated descriptors when it comes to extrapolating towards larger experimentally relevant complexes. Exchange spin coupling is similarly easy to learn as the polarizability, while learning dipole moments is much harder. The strength of the sophisticated descriptors lies in their ability to linearize structure-property relationships, to the point that a simple linear ridge regression performs just as well as the kernel-based machine-learning model for our small dicopper data set. The superior extrapolation performance of the simple descriptor is unique to exchange spin coupling, reinforcing the crucial role of choosing a suitable descriptor, and highlighting the interesting question of the role of chemical intuition vs. systematic or automated selection of features for machine learning in chemistry and material science.

Sewage sludge as a precursor of adsorbents/catalysts for environmental applications

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
A. Ros ◽  
C. Canals-Batlle ◽  
M.A. Lillo-Ródenas ◽  
E. Fuente ◽  
M. A. Montes-Morán ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Room Temperature ◽  
Waste Water Treatment ◽  
Textural Properties ◽  
Active Species ◽  
Elemental Sulphur ◽  
Gaseous Emissions ◽  
Removal Experiments ◽  
Catalytically Active

This paper focuses on the valorisation of solid residues obtained from the thermal treatment of sewage sludge. In particular, sewage sludge samples were collected from two waste water treatment plants (WWTPs) with different sludge line basic operations. After drying, sludges were heated up to 700 °C in appropriate ovens under diluted air (gasification) and inert (pyrolysis) atmospheres. The solids obtained, as well as the dried (raw) sludges, were characterised to determine their textural properties and chemical composition, including the speciation of their inorganic fraction. All the materials under study were employed as adsorbents/catalysts in H2S removal experiments at room temperature. It was found that, depending on the particular sludge characteristics, outstanding results can be achieved both in terms of retention capacities and selectivity. Some of the solids outperform commercially available sorbents specially designed for gaseous emissions control. In these adsorbents/catalysts, H2S is selectively oxidised to elemental sulphur most likely due to the presence of inorganic, catalytically active species. The role of the carbon-enriched part on these solids is also remarked.

The Role of microRNAs in the Viral Infections

2019 ◽  
Vol 24 (39) ◽  
pp. 4659-4667 ◽  
Author(s):  
Mona Fani ◽  
Milad Zandi ◽  
Majid Rezayi ◽  
Nastaran Khodadad ◽  
Hadis Langari ◽  
...  
Keyword(s):  
Viral Infections ◽  
Rna Viruses ◽  
Regulation Of Gene Expression ◽  
Molecular Structures ◽  
Main Function ◽  
Cellular Functions ◽  
Viral Genes ◽  
Non Coding Rnas ◽  
Post Transcriptional Regulation

MicroRNAs (miRNAs) are non-coding RNAs with 19 to 24 nucleotides which are evolutionally conserved. MicroRNAs play a regulatory role in many cellular functions such as immune mechanisms, apoptosis, and tumorigenesis. The main function of miRNAs is the post-transcriptional regulation of gene expression via mRNA degradation or inhibition of translation. In fact, many of them act as an oncogene or tumor suppressor. These molecular structures participate in many physiological and pathological processes of the cell. The virus can also produce them for developing its pathogenic processes. It was initially thought that viruses without nuclear replication cycle such as Poxviridae and RNA viruses can not code miRNA, but recently, it has been proven that RNA viruses can also produce miRNA. The aim of this articles is to describe viral miRNAs biogenesis and their effects on cellular and viral genes.

Anthocyanins: Chemical Properties and Health Benefits: A Review

2021 ◽  
Vol 17 ◽  
Author(s):  
Siraj Salman Mohammad ◽  
Renata Oliveira Santos ◽  
Maria Ivone Barbosa ◽  
José Lucena Barbosa Junior
Keyword(s):  
Raw Materials ◽  
Health Benefits ◽  
Chemical Properties ◽  
Extraction Methods ◽  
The Body ◽  
Raw Material ◽  
Extraction Properties ◽  
Therapeutic Properties ◽  
Food Processes ◽  
Shed Light

: Anthocyanins are widely spread in different kinds of food, especially fruits and floral tissues, there is an extensive range of anthocyanin compounds reach more than 600 exist in nature. Anthocyanins can be used as antioxidants and raw material for several applications in food and pharmaceutical industry. Consequently, a plenty of studies about anthocyanins sources and extraction methods were reported. Furthermore, many studies about their stability, bioactive and therapeutic properties have been done. According to the body of work, we firstly worked to shed light on anthocyanin properties including chemical, antioxidant and extraction properties. Secondly, we reported the applications and health benefits of anthocyanin including the applications in food processes and anthocyanin characteristics as therapeutic and prophylactic compounds. We reviewed anticancer, anti-diabetic, anti-fatness, oxidative Stress and lipid decreasing and vasoprotective effects of anthocyanins. In conclusion, because the importance of phytochemicals and bioactive compounds the research is still continuing to find new anthocyanins from natural sources and invest them as raw materials in the pharmaceutical and nutrition applications.

Introduction to geomicrobiology

2018 ◽  
Author(s):  
David L. Kirchman
Keyword(s):  
Fossil Fuels ◽  
Solid Phase ◽  
Direct Reduction ◽  
Iron Oxidation ◽  
Mineral Dissolution ◽  
Precipitation Process ◽  
Soluble Ions ◽  
Chemolithoautotrophic Bacteria ◽  
The Impact

Geomicrobiology, the marriage of geology and microbiology, is about the impact of microbes on Earth materials in terrestrial systems and sediments. Many geomicrobiological processes occur over long timescales. Even the slow growth and low activity of microbes, however, have big effects when added up over millennia. After reviewing the basics of bacteria–surface interactions, the chapter moves on to discussing biomineralization, which is the microbially mediated formation of solid minerals from soluble ions. The role of microbes can vary from merely providing passive surfaces for mineral formation, to active control of the entire precipitation process. The formation of carbonate-containing minerals by coccolithophorids and other marine organisms is especially important because of the role of these minerals in the carbon cycle. Iron minerals can be formed by chemolithoautotrophic bacteria, which gain a small amount of energy from iron oxidation. Similarly, manganese-rich minerals are formed during manganese oxidation, although how this reaction benefits microbes is unclear. These minerals and others give geologists and geomicrobiologists clues about early life on Earth. In addition to forming minerals, microbes help to dissolve them, a process called weathering. Microbes contribute to weathering and mineral dissolution through several mechanisms: production of protons (acidity) or hydroxides that dissolve minerals; production of ligands that chelate metals in minerals thereby breaking up the solid phase; and direct reduction of mineral-bound metals to more soluble forms. The chapter ends with some comments about the role of microbes in degrading oil and other fossil fuels.

Energy Markets and Trading

2018 ◽  
Author(s):  
David Mares
Keyword(s):  
Fossil Fuels ◽  
Negative Impact ◽  
Adjustment Costs ◽  
Institutional Context ◽  
Energy Markets ◽  
Energy Resources ◽  
Trade Offs ◽  
The Social ◽  
Impact Risk

This chapter discusses the role of energy in economic development, the transformation of energy markets, trade in energy resources themselves, and the geopolitical dynamics that result. The transformation of energy markets and their expansion via trade can help or hinder development, depending on the processes behind them and how stakeholders interact. The availability of renewable, climate-friendly sources of energy, domestically and internationally, means that there is no inherent trade-off between economic growth and the use of fossil fuels. The existence of economic, political, social, and geopolitical adjustment costs means that the expansion of international energy markets to incorporate alternatives to oil and coal is a complex balance of environmental trade-offs with no solutions completely free of negative impact risk. An understanding of the supply of and demand for energy must incorporate the institutional context within which they occur, as well as the social and political dynamics of their setting.

scholarly journals Rheological Characterization of a Concentrated Phosphate Slurry

Fluids ◽  
2021 ◽  
Vol 6 (5) ◽  
pp. 178
Author(s):  
Souhail Maazioui ◽  
Abderrahim Maazouz ◽  
Fayssal Benkhaldoun ◽  
Driss Ouazar ◽  
Khalid Lamnawar
Keyword(s):  
Flow Behavior ◽  
Continuous Phase ◽  
Raw Material ◽  
Rheological Characterization ◽  
Phosphate Ore ◽  
Insoluble Particles ◽  
Experimental Protocols ◽  
Solid Liquid

Phosphate ore slurry is a suspension of insoluble particles of phosphate rock, the primary raw material for fertilizer and phosphoric acid, in a continuous phase of water. This suspension has a non-Newtonian flow behavior and exhibits yield stress as the shear rate tends toward zero. The suspended particles in the present study were assumed to be noncolloidal. Various grades and phosphate ore concentrations were chosen for this rheological investigation. We created some experimental protocols to determine the main characteristics of these complex fluids and established relevant rheological models with a view to simulate the numerical flow in a cylindrical pipeline. Rheograms of these slurries were obtained using a rotational rheometer and were accurately modeled with commonly used yield-pseudoplastic models. The results show that the concentration of solids in a solid–liquid mixture could be increased while maintaining a desired apparent viscosity. Finally, the design equations for the laminar pipe flow of yield pseudoplastics were investigated to highlight the role of rheological studies in this context.

scholarly journals Contribution of Cyanotoxins to the Ecotoxicological Role of Lichens

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 321
Author(s):  
Dobri Ivanov ◽  
Galina Yaneva ◽  
Irina Potoroko ◽  
Diana G. Ivanova
Keyword(s):  
Research Methods ◽  
Raw Material ◽  
Modern Times ◽  
Effective Application ◽  
The World ◽  
The Common

The fascinating world of lichens draws the attention of the researchers because of the numerous properties of lichens used traditionally and, in modern times, as a raw material for medicines and in the perfumery industry, for food and spices, for fodder, as dyes, and for other various purposes all over the world. However, lichens being widespread symbiotic entities between fungi and photosynthetic partners may acquire toxic features due to either the fungi, algae, or cyano-procaryotes producing toxins. By this way, several common lichens acquire toxic features. In this survey, recent data about the ecology, phytogenetics, and biology of some lichens with respect to the associated toxin-producing cyanoprokaryotes in different habitats around the world are discussed. Special attention is paid to the common toxins, called microcystin and nodularin, produced mainly by the Nostoc species. The effective application of a series of modern research methods to approach the issue of lichen toxicity as contributed by the cyanophotobiont partner is emphasized.

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