Major Degradation Process Research Articles

On the potential impact of root system size and density on salt distribution in the root zone

Soil salinization in agricultural environments is a major soil degradation process, particularly in dry regions. Soil salinization puts at risk the natural ecosystem and the agricultural crops, which are usually sensitive to elevated salinities. In this work, a conceptual model is proposed and tested experimentally, to examine the impact of root system dimension and distribution on solute transport and accumulation in the root zone. For this purpose, tomatoes were grown in growing chambers, under conditions of salty water irrigation. Root density, salt concentration and soil water content distributions were measured and correlations between the three parameters were found for different root system sizes. Results show that confined root systems were highly salinized with a strong correlation between root location and salt distribution in the soil. Broad root systems, on the other hand, showed a reduction in soil bulk salinity at the root zone and that about 50 % of the root system is under conditions of low salinity. The physical reasons for this observation are proposed herein and it is suggested that in the future, development of crops with large root systems could be considered as another tool to cope with soil salinization.

Acute Heat Exposure Alters Autophagy Signaling in C2C12 Myotubes.

Autophagy is a major intracellular degradation process that is essential for the clearance of unnecessary proteins/organelles and the maintenance of cellular homeostasis. The inhibition of autophagy results in cellular consequences associated with many skeletal muscle pathologies, and therapies designed to elevate autophagic activity may provide protection from such pathologies. Acute exposure to low levels of heat has therapeutic effects; however, the impact of heat on skeletal muscle autophagy remains unclear. In the present study, C2C12 myotubes were maintained at 37°C thermoneutral (TN) or heated at 40°C heat treatment (HT) for 1 h. Myotubes were harvested immediately after heating, or returned to 37°C for recovery of 2 or 24 h. HT resulted in an elevation in pAMPK (T172), Beclin-1, and LC3 II, a marker for autophagosome formation, but no change in p62. In the context of autophagy inhibition with Bafilomycin A1, HT resulted in lower LC3 II compared to TN. The applied heat load induced the heat shock response, as evidenced by immediate upregulation of HSF1 and Hsp70. Hsp70 continued to increase during recovery, whereas pHsp27 was downregulated acutely in response to HT, but retuned to TN levels by 2 h of recovery. HT also reduced the phosphorylation of the MAP-kinases p38 and JNK. These findings suggest that an acute, short bout of mild heat may be beneficial to skeletal muscle by increasing AMPK activity, markers of autophagasome formation, and the heat shock response.

Chlorine Isotope Fractionation of the Major Chloromethane Degradation Processes in the Environment.

Chloromethane (CH3Cl) is an important source of chlorine in the stratosphere, but detailed knowledge of the magnitude of its sources and sinks is missing. Here, we measured the stable chlorine isotope fractionation (εCl) associated with the major abiotic and biotic CH3Cl sinks in the environment, namely, CH3Cl degradation by hydroxyl (·OH) and chlorine (·Cl) radicals in the troposphere and by reference bacteria Methylorubrum extorquens CM4 and Leisingera methylohalidivorans MB2 from terrestrial and marine environments, respectively. No chlorine isotope fractionation was detected for reaction of CH3Cl with ·OH and ·Cl radicals, whereas a large chlorine isotope fractionation (εCl) of -10.9 ± 0.7‰ (n = 3) and -9.4 ± 0.9 (n = 3) was found for CH3Cl degradation by M. extorquens CM4 and L. methylohalidivorans MB2, respectively. The large difference in chlorine isotope fractionation observed between tropospheric and bacterial degradation of CH3Cl provides an effective isotopic tool to characterize and distinguish between major abiotic and biotic processes contributing to the CH3Cl sink in the environment. Our findings demonstrate the potential of emerging triple-element isotopic approaches including chlorine to carbon and hydrogen analysis for the assessment of global cycling of organochlorines.

Application of the Soil Security Concept to Two Contrasting Soil Landscape Systems—Implications for Soil Capability and Sustainable Land Management

Soil security identifies global challenges and a series of dimensions that are necessary requirements to meet those global challenges using sustainable land management. The soil security concept is applied to two contrasting soil landscape systems with varying climate, landform and soil types. Previous methodologies for assessing land and soil capability are combined within the soil security conceptual approach. The land and soil capability methodologies are used to assess how the soil condition changes in response to the stresses and forcing associated with land management and land and soil degradation processes. It is the soil capability that defines how the soil condition changes between the reference state of the soil condition, or the genoform, and the soil condition under land use, or the phenoform. The conclusion is that soil capability, which is one of the dimensions used to apply the soil security concept, is a complex dimension and has several aspects or further facets to be considered to achieve sustainable land management. It is apparent that in assessing soil capability, the following facets are relevant. I: The capacity of the soil to provide ecosystem services to meet the global challenges outlined for Soil Security. II: The stability of the soil condition to land degradation processes resulting from the effects of land management practices and the environmental stresses on the soil. III: The capacity to recover following degradation. Facets II and III can be considered the resilience. An important conclusion is that the soil capability cannot be assessed without taking into account features of the landscape including climate and landform. Two examples from south eastern Australia of the application of these facets of soil capability to on-ground situations are presented. The Cowra Trough Red Soils in the Australian wheat belt are a set of soils, primarily contributing to meeting the global challenge of food security. The major degradation processes threatening the stability of these soils are water erosion and soil acidification. The Kosciusko National Park in the Snowy Mountains region is primarily contributing to meeting the challenges of water security for the irrigation industry in the Murray Darling Basins and energy security through the production of hydroelectricity. The set of soil landscapes also contributes to biodiversity protection and human health and well-being. The major degradation processes threatening the stability of these soils and their capacity to meet the global challenges are water and wind erosion. A major limitation is the poor capacity of these soils to recover once degraded. Identifying the main ecosystem services provided by the two examples, together with the major risks of land degradation can clarify extension, economic and policy aspects of sustainable land management for the two sets of soil landscapes. For the Cowra Trough Red Soils, management of water erosion and soil acidification are essential for maintaining the contribution of the area to food security. For the Kosciusko National Park, the control of water and wind erosion are essential to maintain the contribution of the area to water and energy security.

Degradation characteristics of membrane electrode assembly under drive cycle test protocol

ABSTRACTOne of the key factors determining the lifetime of proton exchange membrane fuel cell (PEMFC) is the degradation and eventually the failure of membrane electrode assembly (MEA). To assess the long-term durability of MEA in fuel cells for vehicular applicatoin, this study adopted the accelerating technique using drive cycle test protocol developed by Chinese NERC Fuel Cell & Hydrogen Technology. The protocol includes starts/stops, idling, and acceleration, simulating major degradation processes in real automobile application. After 900 h of accelerated test, MEA’s performance declined from the initial 0.65 V to 0.58 V@500 mA cm−2, dropping by more than 10% and giving an average voltage decay rate of 70 μV h−1. To examine the underlying mechanisms for the degradation, post-mortem analyses such as X-ray photoelectric spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDX) were carried out for the MEA before and after 900 h drive cycle test. The post-mortem analyses indicate that the thinning of the electrolyte membrane at H2 outlet region is the decisive factor leading to the end-of-life of PEMFC, and the Pt catalysts loss and microstructural damage of MEA are the decisive factors for the performance degradation and stability deterioration of PEMFC.

WYBRANE ASPEKTY DEGRADACJI GLEB

The paper presents the problems of various type of forest soil degradations. Soil degradation is characterized by a decline in quality and decrease in ecosystems goods and it is unfavorable phenomenon. Soil is a non-renewable resource and its vulnerability to degradation depends on complex interactions between processes, factors and causes occurring at spatial and temporal scales. Both natural and antropogenic factors and processes are listed as possible causes of soil degradation. Erosion, depletion of the soil organic carbon, loss of soil fertility and biodiversity as well as acidification are particularly fast and noticeable among the major soil degradation processes.

Role of the Ubiquitin Proteasome System (UPS) in the HIV-1 Life Cycle.

Given that the ubiquitin proteasome system (UPS) is the major protein degradation process in the regulation of a wide variety of cellular processes in eukaryotic cells, including alteration of cellular location, modulation of protein activity, and regulation of protein interaction, it is reasonable to suggest that the infecting HIV-1 and the invaded hosts exploit the UPS in a contest for survival and proliferation. However, to date, regulation of the HIV-1 life cycle has been mainly explained by the stage-specific expression of HIV-1 viral genes, not by elimination processes of the synthesized proteins after completion of their duties in the infected cells, which is also quintessential for understanding the molecular processes of the virus life cycle and thereby HIV-1 pathogenesis. In fact, several previous publications have indicated that the UPS plays a critical role in the regulation of the proteasomal degradation of viral and cellular counterparts at every step of the HIV-1 life cycle, from the virus entry to release of the assembled virus particles, which is integral for the regulation of survival and proliferation of the infecting HIV-1 and to replication restriction of the invading virus in the host. However, it is unknown whether and how these individual events taking place at different stages of the HIV-1 life cycle are orchestrated as an overall strategy to overcome the restrictions conferred by the host cells. Thus, in this review, we overview the interplay between HIV-1 viral and cellular proteins for restrictions/competitions for proliferation of the virus in the infected cell, which could open a new avenue for the development of therapeutics against HIV-1 via targeting a specific step of the proteasome degradation pathway during the HIV-1 life cycle.

Thermal properties of charring plasticizers from the biobased alcohols, pentaerythritol and 3,5-dihydroxybenzoic acid

To be converted into a useful commercial material, poly(vinyl chloride) (PVC) must generally be heavily plasticized. Owing to its high level of chlorine, PVC is not flammable (limiting oxygen index of 45). However, addition of a plasticizer usually imparts appreciable flammability. The plasticizer is often volatilized from the polymer when it is exposed to heat. In general, plasticizers burn readily and may be the source of the flammability of formulated polymers. This flammability might be controlled by using effective plasticizers that promote char formation at the surface of the burning polymer. Two series of charring compounds, pentaerythritol esters containing aromatic moieties and phosphorus esters of 3,5-dihydroxybenzoates, have been demonstrated to be effective plasticizers for PVC. The thermal degradation of both series of compounds has been examined using thermogravimetry and infrared spectroscopy. For both sets of esters, elimination of an acid is a major degradation process. For the degradation of pentaerythritol esters, a carboxylic acid is a primary degradation product. For the alkyl 3,5-(diphenylphosphato)benzoates, degradation may lead to the formation of either a carbon or a phosphorus acid depending on structure.

The role of photodegradation in the environmental fate of hydroxychloroquine

For many organic pollutants present in surface waters, photolysis is considered as a major abiotic degradation process. The present study aimed to explore the role of photolysis in the environmental fate of hydroxychloroquine (HCQ) for the first time. The photolytic degradation of HCQ was investigated under simulated solar radiation (300–800 nm) in ultrapure, spring, river, and sea water. The effect of pH on the photodegradation rate was substantial and it was observed that degradation was faster at higher pH-values. Obtained half-lives ranged from 5.5 min at pH 9 to 23.1 h at pH 4. Humic acids, nitrate and iron(III) enhanced photodegradation of HCQ due to formation of hydroxyl radicals and its attack on HCQ molecule. In contrast, chloride, sulfate and bromide inhibited photodegradation. Additionally, the humic acids exhibited a dual role, photosensitization and inner filter effect. The study of the reaction kinetics was performed with HPLC-PDA, while the identification of degradation products formed during photolytic degradation was carried out using HPLC-MS/MS and NMR spectroscopy. The hydroxylation was recognized as the dominant path of photoproducts formation. The results of this research reveal the importance of photolytic degradation in environmental fate of HCQ and enable a better understanding of its behavior in the environment. Moreover, the results showing the significant effect of pH on the photodegradation of HCQ can be very useful in water treatment processes.

The (Evolving) Vineyard’s Age Structure in the Valencian Community, Spain: A New Demographic Approach for Rural Development and Landscape Analysis

Vineyards have assumed a key role as rural landmarks in recent decades. Investigating vineyard dynamics and contexts may reveal various economic, cultural, and environmental aspects of rural landscapes, which can be linked to land-use changes and major soil degradation processes, including soil erosion. As a contribution to rural landscape studies, the purpose of this work is to investigate the spatial distribution of vineyard plots in the Valencian community, located in the eastern area of the Iberian Peninsula, focusing on the final product, the type of vineyard and how long each vineyard has been settled over time. The work provides a comprehensive analysis of a wine-growing landscape, considering strategic (spatial) assets in present and past times. Vineyards were interpreted as a distinctive landmarks that give value to local economies; basic knowledge of how long different types of wine plots have been present in the Valencian community is useful when estimating their degree of sustainability and formulating suggestions, policies, and strategies to prevent processes of landscape degradation at various spatial scales.

Synthesis of LaFeO3/Ag2CO3 Nanocomposites for Photocatalytic Degradation of Rhodamine B and p-Chlorophenol under Natural Sunlight.

Novel LaFeO3/Ag2CO3 nanocomposites are synthesized by co-precipitation method for photocatalytic degradation of Rhodamine B (RhB) and p-chlorophenol under visible light irradiation. Heterostructures between LaFeO3 and Ag2CO3 semiconductors are formed during the synthesis of these nanocomposites. Among the nanocomposites prepared with different ratios of LaFeO3 and Ag2CO3, 1% LaFeO3/Ag2CO3 shows the highest photocatalytic activity for the degradation of RhB. Maximum electron–hole pair decoupling efficiency is observed in 1% LaFeO3/Ag2CO3, which causes the greater activity of the heterostructure. Degradation efficiency of 99.5% for RhB and 59% for p-chlorophenol has been obtained under natural sunlight within 45 min. Interestingly, the stability of Ag2CO3 is improved dramatically after making nanocomposite, and no decomposition of the catalyst was observed even after several photocatalytic cycles. Reactive oxygen species scavenging experiments with p-benzoquinone, isopropyl alcohol, and ammonium oxalate suggest that a major degradation process is caused by holes. Degradation of RhB into small organic moieties is detected using LC–MS technique. Further, the efficient mineralization of the degradation products occurs during the catalytic process.

Autophagy and the Metabolism of Misfolding Protein.

Autophagy is a major intracellular degradative process that delivers cytoplasmic materials to the lysosome for degradation. An increasing number of studies on the physiological and pathological roles of autophagy in a variety of autophagy knockout models and human diseases were carried out. Among them, the clearance of misfolded proteins is the important function of autophagy. Impairment at different steps of the autophagy system, such as the ubiquitin-proteasome and the autophagy-lysosome pathways, may result in the accumulation of misfolded proteins in insoluble aggregates. Abnormal accumulation of misfolded proteins in cells can lead to a variety of human diseases. Here, we review the major advances in autophagy and the metabolism of misfolding protein in human diseases. Current studies about the promising therapeutic strategy in autophagy-modulating are also summarized.

Upregulation of autophagy by Ginsenoside Rg2 in MCF-7 cells

ABSTRACTAutophagy is a major intracellular degradation process that plays an important role in cell survival, stress responses, nutrient sensing and development. Our previous studies have shown that Rg2, a triterpenoid saponin contained in ginseng, protects cells against UVB-induced genotoxicity by increasing DNA repair, in possible association with modulation of protein levels involved in p53 pathway. In this study, we determined an upregulation of autophagy by Rg2. Rg2 treatment for 24 h in MCF-7, a breast cancer cell, did not show cytotoxicity up to 200 μM. Rg2 also upregulated the level of p-p53, p-AMPK, p-ACC, Atg-7 and LC3-II and decreased the level of p62 in concentration-dependent manners. We also determined the level of p53, AMPK, p62, Atg-7 and LC3 after UVB exposure and subsequent incubation in growth medium for 24 h. UVB increased the level of p-p53, p-AMPK, p-ACC and decreased the levels of p62, Atg-7 and LC3-II. Interestingly, Rg2 treatment for 24 h after UVB exposure increased the levels of p-p53, p-AMPK, p-ACC, Atg-7 and LC3-II and decreased the level of cyclobutane pyrimidine dimer, a UVB-induced DNA damage in concentration-dependent manners. All these results suggest that Rg2 increased autophagy and decreased UVB-induced DNA damage, in possible association with the modulation of protein levels in p53- and autophagic pathways.

Effects of light, microorganisms, farming chemicals and water content on the degradation of microcystin-LR in agricultural soils

An experiment was conducted to investigate the effect of farming activities on microcystin-LR (MC-LR) degradation in soils. Three farming activities were assessed: 1) fertilization via addition of different nitrogen sources and organic matter; 2) pesticide application by addition of different commercial pesticides; and 3) irrigation by addition of different amount of water. The contribution of the two major degradation processes of MC-LR in soils, photodegradation and biodegradation, were also evaluated. MC-LR was added into the soil samples to create a concentration of 500 μg kg−1 for each treatment. Results showed that natural degradation of MC-LR in soils was mainly by biodegradation rather than photodegradation. MC-degradation was stimulated by the addition of NaNO3 and humic acid, whereas degradation was inhibited by addition of NH4Cl, glucose, and glycine. Application of high concentrations of glyphosate and chlorothalonil significantly inhibited the degradation of MC-LR in soils and the half-life was almost twice as long as the control. No significant effect was found by addition of CO(NH2)2 and dimethoate. Both low (10%) and high water content (60%) could lead to inhibition of MC-LR degradation. Results from our study help to inform farm practices that could alleviate contamination by MC-LR in agroecosystems.

Acceleration tests: Degradation of anode-supported planar solid oxide fuel cells at elevated operating temperatures

As the solid oxide fuel cell (SOFC) technology matures, durability under real operating conditions is considered as one of the most critical issues for commercialization. The severe conditions encountered in practical operation include a large temperature gradient and generation of local hot spots within stacks. Herein, we report the degradation mechanisms of anode-supported planar SOFCs supplied by Posco Energy at elevated operating temperatures. A simple comparison of the voltage reduction rates at different operating temperatures does not appropriately represent the degree of degradation, because the rapid deterioration of the cell components at high temperatures is compensated for by the fast reaction and transport kinetics. A combination of impedance interpretation and post-mortem analysis reveals the major degradation processes that are distinctively accelerated by increasing temperature, including the chemical interaction between the cathode and electrolyte, the enlargement of the interfacial pores, the coarsening of the fine particles in the composite electrodes, the formation of interfacial cracks and Cr poisoning. Systematic analysis presented in this study provides guidelines for counteracting the unexpected temperature increase, and the database established under various extreme conditions would form the groundwork for achieving the lifetime goals of commercial SOFC systems.

Chaperone-mediated autophagy compensates for impaired macroautophagy in the cirrhotic liver to promote hepatocellular carcinoma.

Macroautophagy and chaperone-mediated autophagy (CMA) represent two major lysosomal degradation processes and often compensate for one another to facilitate cell survival. The aim of this study was to determine whether these autophagy pathways could compensate for one another to promote HCC cell survival in the cirrhotic liver. Analysis of normal liver tissue showed no expression of glypican-3 or p62 proteins, suggesting that macroautophagy is the major contributor to autophagic flux under non-pathological conditions. Of 46 cirrhotic livers with HCC examined, 39 (84%) of HCCs showed increased expression of p62, and 36 (78%) showed increased expression of glypican-3, while adjacent non-tumorous hepatocytes were negative for expression of p62 and glypican-3, similar to normal liver tissue. These results suggest that macroautophagy flux is impaired in HCC. Furthermore, more than 95% of HCCs showed altered expression of LAMP-2A compared to the surrounding non-tumorous cirrhotic liver, consistent with induction of CMA in HCC. Elevated expression of glucose-regulated protein 78 (GRP78) and heat shock cognate protein (Hsc70) were detected in 100% of HCC and adjacent non-tumorous cirrhotic livers, suggesting that unresolved ER-stress is associated with HCC risk in liver cirrhosis. Interestingly, inhibition of lysosomal degradation using hydroxychloroquine (HCQ) induced expression of the tumor suppressor p53, promoted apoptosis, and inhibited HCC growth, whereas activation of autophagy using an mTOR inhibitor (Torin1) promoted HCC growth. Results of this study suggest that induction of CMA compensates for the impairment of macroautophagy to promote HCC survival in the cirrhotic liver.

Influence of local lithium metal deposition in 3D microstructures on local and global behavior of Lithium-ion batteries

One of the major degradation processes in lithium ion batteries is the deposition of metallic lithium on the surface of the active particles in the negative electrode. In this paper we present a fully 3D microstructure resolved simulation of the influence of plated lithium on the cell potential during discharge depending on the amount and position of plated lithium. Our simulations give insight on the most probable position of the first occurrence of plating within the electrode depending on applied current and ambient temperatures as well as on the subtle local electric current distributions during stripping of plated lithium upon discharge. Specifically a stripping induced intercalation of lithium ions in the supporting graphite material during discharge is discovered. This phenomenon, easily accessible to microstructure resolved simulations, leads to a violation of the relation between transferred charge during stripping and the amount of plated lithium. As a consequence the amount of plated lithium cannot be uniquely determined from the applied current and the length of the potential plateau during stripping. We show that the value and length of the plateau depends on the amount of plated lithium, the fraction of the surface area covered by lithium and the applied current.

A salinização do solo em Portugal. Causas, extensão e soluções

Soil salinization is a major soil degradation process. In Portugal, this problem is limited to marshes and some irrigated areas located in the south of the country. However, the increase of the irrigated area and the prospects of climate change for the coming decades, including rising temperatures, can lead to an increase of the degraded areain Portugal. This paper describes the main causes of soil salinization/sodicization, the most relevant indicators, and the most used classifications. The main areas in Portugal affected, either by natural salinization or by secondary salinization, are also indicated. Then,some of the most relevant studies related to saline soilsmapping, the use of saline and sodic soils, and the use of poor quality waters conducted in Portugal,are also reviewed. Finally, the main methods for preventing and recovering saline/sodic soils are addressed.

Lithium Plating and Stripping in the Framework of a 3D Electrochemical Model

One of the major degradation processes in lithium-ion batteries is lithium plating. This mechanism describes the growth of a parasitic metallic lithium phase on the surface of the negative electrode. We present an extension to a 3D transport model, which allows for deposition and dissolution of an additional metallic lithium phase inside of a lithium-ion battery. The effect of lithium stripping and plating on the cell voltage can be investigated.

Restoring Soil Quality to Mitigate Soil Degradation

Feeding the world population, 7.3 billion in 2015 and projected to increase to 9.5 billion by 2050, necessitates an increase in agricultural production of ~70% between 2005 and 2050. Soil degradation, characterized by decline in quality and decrease in ecosystem goods and services, is a major constraint to achieving the required increase in agricultural production. Soil is a non-renewable resource on human time scales with its vulnerability to degradation depending on complex interactions between processes, factors and causes occurring at a range of spatial and temporal scales. Among the major soil degradation processes are accelerated erosion, depletion of the soil organic carbon (SOC) pool and loss in biodiversity, loss of soil fertility and elemental imbalance, acidification and salinization. Soil degradation trends can be reversed by conversion to a restorative land use and adoption of recommended management practices. The strategy is to minimize soil erosion, create positive SOC and N budgets, enhance activity and species diversity of soil biota (micro, meso, and macro), and improve structural stability and pore geometry. Improving soil quality (i.e., increasing SOC pool, improving soil structure, enhancing soil fertility) can reduce risks of soil degradation (physical, chemical, biological and ecological) while improving the environment. Increasing the SOC pool to above the critical level (10 to 15 g/kg) is essential to set-in-motion the restorative trends. Site-specific techniques of restoring soil quality include conservation agriculture, integrated nutrient management, continuous vegetative cover such as residue mulch and cover cropping, and controlled grazing at appropriate stocking rates. The strategy is to produce “more from less” by reducing losses and increasing soil, water, and nutrient use efficiency.