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We explored the aging effects on insulating materials used in power transformers through dielectric spectroscopy. Frequency domain spectroscopy (FDS) was conducted for both aged and new Kraft paper and pressboard samples to determine their dielectric properties across a temperature range of 40–100 ℃ for pressboard and 40–70 ℃ for Kraft paper. Principal component analysis (PCA) was employed to classify the data, identify key factors contributing to variance, and elucidate the relationships between different parameters. The analysis revealed positive correlations between conductivity and frequency, as well as between permittivity and tan delta, with distinct differences in behavior observed between aged and new samples at lower frequencies. Additionally, the impact of temperature was evident, with increased temperature leading to an upward shift in dielectric behavior. At lower temperatures, aging had a reduced effect on the materials' properties. These findings provide significant insights into the dielectric behavior and aging mechanisms of insulation materials in power transformers.

For about two millennia, paper has served as a main medium for preservation of people’s ideas, stories, contracts, and art. This article reviews what is known about the various components that make up paper from the perspective of their long-term stability under typical storage conditions. Literature evidence is considered relative to the susceptibility of different paper components to embrittlement, acid hydrolysis, microbiological attack, and discoloration, among others. The cellulose that makes up a majority of most paper items is demonstrably stable enough to persist for many hundreds of years on the shelves of archival collections, though it is susceptible to acid-catalyzed hydrolysis, which can be accelerated by byproducts of decomposition. Though less attention has been paid to the archival performance of various minor components of modern paper products, evidence suggests that at least some of them are subject to likely breakdown, embrittlement, or decay in the course of prolonged storage. Based on these considerations, one can envision different categories of paper that can be expected to meet different levels of storage stability: ancient recipes for handmade papermaking, e.g. washi and hanji, archival-grade paper products, ordinary modern alkaline paper products, and paper manufactured without concerns for its longevity.

For about two millennia, paper has served as a main medium for preservation of people’s ideas, stories, contracts, and art. This article reviews what is known about the various components that make up paper from the perspective of their long-term stability under typical storage conditions. Literature evidence is considered relative to the susceptibility of different paper components to embrittlement, acid hydrolysis, microbiological attack, and discoloration, among others. The cellulose that makes up a majority of most paper items is demonstrably stable enough to persist for many hundreds of years on the shelves of archival collections, though it is susceptible to acid-catalyzed hydrolysis, which can be accelerated by byproducts of decomposition. Though less attention has been paid to the archival performance of various minor components of modern paper products, evidence suggests that at least some of them are subject to likely breakdown, embrittlement, or decay in the course of prolonged storage. Based on these considerations, one can envision different categories of paper that can be expected to meet different levels of storage stability: ancient recipes for handmade papermaking, e.g. washi and hanji, archival-grade paper products, ordinary modern alkaline paper products, and paper manufactured without concerns for its longevity. [ABSTRACT FROM AUTHOR]

We explored the aging effects on insulating materials used in power transformers through dielectric spectroscopy. Frequency domain spectroscopy (FDS) was conducted for both aged and new Kraft paper and pressboard samples to determine their dielectric properties across a temperature range of 40-100 °C for pressboard and 40-70 °C for Kraft paper. Principal component analysis (PCA) was employed to classify the data, identify key factors contributing to variance, and elucidate the relationships between different parameters. The analysis revealed positive correlations between conductivity and frequency, as well as between permittivity and tan delta, with distinct differences in behavior observed between aged and new samples at lower frequencies. Additionally, the impact of temperature was evident, with increased temperature leading to an upward shift in dielectric behavior. At lower temperatures, aging had a reduced effect on the materials' properties. These findings provide significant insights into the dielectric behavior and aging mechanisms of insulation materials in power transformers. [ABSTRACT FROM AUTHOR]

In order to determine the influence of bast fibers isolated from Wikstroemia bark on the durability of paper, self-made paper was prepared using bagasse pulp mixed with Wikstroemia bark pulp using Kaihua paper manufacturing technology. The durability properties of the paper obtained with different proportions of Wikstroemia bark pulp were measured and analyzed. The results showed that Wikstroemia bark can lower the acidity, improve the mechanical strength, and delay the aging of paper. The mechanical strength showed an exponential relationship with the amount of Wikstroemia bark pulp added to the paper pulp. There was a linear positive correlation between the initial polymerization degree of the paper and the amount of Wikstroemia bark pulp, while the molecular fracture rate of the paper with Wikstroemia bark pulp was considerably reduced. Wikstroemia bark fibers are long fibers with high strength. At the same time, Wikstroemia bark fibers differ greatly in length, so the uniformity can meet the requirements. The durability of the paper made from only bagasse pulp was poor, but the overall strength and polymerization degree of the paper improve after being mixed with Wikstroemia bark pulp.

Italy’s demographic setting is rapidly evolving and is characterized by a substantial increase in the older population segment. This trend, driven by prolonged life expectancy and declining birth rates, positions Italy as a leader in global aging patterns. The 38th National Congress of the Società Italiana di Geriatria Ospedale e Territorio (SIGOT), held in Rome, underlined the importance of addressing the health needs of this aging population, particularly focusing on preventing sarcopenia and cardiovascular diseases. Recent data challenge the notion of functional decline as an inevitable consequence of aging, highlighting the interplay of genetic, environmental, and lifestyle factors in modulating health outcomes. Sarcopenia, a prevalent condition and biological substrate of frailty, significantly impacts physical function and mortality rates, necessitating behavioral interventions to mitigate its effects. Physical exercise emerges as a key strategy for maintaining cardiovascular health and reducing the risk of arrhythmias, prevalent in older age groups. However, the complex relationship between physical activity intensity, age, and cardiovascular risk underlines the importance of tailored interventions and preliminary screenings. Looking ahead, proactive measures such as enhanced screening, promoting lifelong healthy habits, research and innovation, robust community support systems, and adaptable policies are essential to address the multifaceted challenges posed by an aging population. With this consensus paper, we aimed to summarize the key messages from the three intensive days of the SIGOT National Congress.

The aging of paper depends on various factors, including environmental conditions, microbiological factors and chemical composition. Chitosan-coated paper is an eco-friendly material that has potential use in various packaging applications due to its mechanical, barrier and antibacterial properties. In this study, the aging stability of chitosan-coated wood-free wrapping paper was evaluated by examining pulp and four paper samples with different quantities of chitosan. Accelerated thermal aging and dynamic thermogravimetric analysis were used to assess the aging stability, while color changes were examined to understand the impact of chitosan coating. The study found that increasing chitosan coating led to improved aging stability due to the improved crosslinking process between chitosan and paper. The coated paper samples displayed a yellowish hue after 72 h of aging, with increased strength and resistance to weight loss. TGA results indicated that the temperature of complete burning of the sample increased with increasing chitosan coating. Additionally, coated paper samples exhibited a more even surface and improved barrier properties. Overall, chitosan-coated paper is a promising material for sustainable and eco-friendly packaging, printing and wrapping applications. This study's findings have important implications for the development of environmentally-friendly packaging materials that possess desirable mechanical and barrier properties. [ABSTRACT FROM AUTHOR]

Background: The Inventory of Physical Activity Barriers (IPAB) assesses physical activity participation barriers. Development, refinement, and psychometric evaluation of the IPAB occurred via an electronic format. However, various circumstances may require using a pen-and-paper format. As instrument formats are not always interchangeable, the authors aimed to establish whether 2 different formats (electronic and pen and paper) can be used interchangeably for the IPAB. Methods: This randomized crossover study included 66 community-dwelling adults aged 50 years and older (mean age = 73 [SD = 7.6]). Half the sample completed the electronic format of the IPAB first and the pen-and-paper format second, and the other half completed them in reverse order. Tests of equivalence and a Bland–Altman plot were performed. Results: The intraclass correlation coefficient between formats was.94, and kappa was.68. The mean difference between the 2 administration forms of the IPAB was 0.002 (P =.96). Both administration formats had high internal consistency (Cronbach alpha =.92 and.93) and illustrated construct validity (P ≤.001 for both administration formats). Conclusion: Pen-and-paper and electronic formats of the IPAB are equivalent and, thus, can be used interchangeably among non-Hispanic whites who are highly educated. The format should be used consistently if completing preintervention and postintervention evaluations or comparing scores. [ABSTRACT FROM AUTHOR]

Thermal aging and ultraviolet (UV) irradiation are used as methods to prepare samples of kraft paper spanning its full lifecycle within a high-voltage transformer, from new to end of life. The mechanical break strain is correlated with the degree of polymerization (DP), representing a progressive deterioration of mechanical properties during aging. Subsequent exposure to oil flow mimicking both normal plant operation and reclamation activities shows that aged paper exposed to high rates of flow experiences noticeable surface roughening. Despite this, no measurable erosion occurs even after long-term temperature/flow cycling in used mineral oil containing a notable particulate content. This indicates that kraft paper is unlikely to be eroded by normal reclamation activities, even in a severely aged asset. This confirms the validity of using this approach to extend plant life. [ABSTRACT FROM AUTHOR]

Aging behavior occurs in the storage process of paper archives, which accelerates the aging process of the paper. Therefore, it is important for paper archives management to explore the aging behavior of acidified paper (AP) and to delay or prevent its further aging. The aging behavior of the commonly used university archives paper with artificial acidification were studied by measuring pH value, electrical conductivity, mechanical properties and whiteness. The results show that the pH value, conductivity, mechanical properties and whiteness of AP change significantly compared with the non-acidified raw paper (P). After dry-heat aging treatment, the pH value of AP decreased more obviously than P, which shows more obvious aging degradation and further acidification of AP. During the aging process of AP, the molecular and structural degradation are promoted by the presence of acidic substances, which increase the electrical conductivity of the system. The microstructures of the paper are changed by acidification and aging treatment, and more fiber fracture, etching and microscopic holes are found in the surface SEM images. The reductions of the tensile index and whiteness of AP are also more significant because of the degradation acceleration of the acid. [ABSTRACT FROM AUTHOR]

The accumulation of senescent cells drives inflammaging and increases morbidity of chronic inflammatory lung diseases. Immune responses are built upon dynamic changes in cell metabolism that supply energy and substrates for cell proliferation, differentiation, and activation. Metabolic changes imposed by environmental stress and inflammation on immune cells and tissue microenvironment are thus chiefly involved in the pathophysiology of allergic and other immune‐driven diseases. Altered cell metabolism is also a hallmark of cell senescence, a condition characterized by loss of proliferative activity in cells that remain metabolically active. Accelerated senescence can be triggered by acute or chronic stress and inflammatory responses. In contrast, replicative senescence occurs as part of the physiological aging process and has protective roles in cancer surveillance and wound healing. Importantly, cell senescence can also change or hamper response to diverse therapeutic treatments. Understanding the metabolic pathways of senescence in immune and structural cells is therefore critical to detect, prevent, or revert detrimental aspects of senescence‐related immunopathology, by developing specific diagnostics and targeted therapies. In this paper, we review the main changes and metabolic alterations occurring in senescent immune cells (macrophages, B cells, T cells). Subsequently, we present the metabolic footprints described in translational studies in patients with chronic asthma and chronic obstructive pulmonary disease (COPD), and review the ongoing preclinical studies and clinical trials of therapeutic approaches aiming at targeting metabolic pathways to antagonize pathological senescence. Because this is a recently emerging field in allergy and clinical immunology, a better understanding of the metabolic profile of the complex landscape of cell senescence is needed. The progress achieved so far is already providing opportunities for new therapies, as well as for strategies aimed at disease prevention and supporting healthy aging. [ABSTRACT FROM AUTHOR]

There is a relative lack of research on the development of creepage discharge in aged oil-paper insulation subjected to AC-DC combined voltage in converter transformers. In this study, based on the physical and chemical properties of oil-paper, we propose a sphere-plate electrode model to study the creepage discharge parameters and characteristic spectra of aged oil-paper subjected to AC-DC combined voltage. The results show that the creepage discharge inception voltage of aged oil-paper is related to the AC voltage component of the AC-DC combined voltage. However, when the DC voltage component is 60 kV, the flashover phenomenon was found to occur in one of the severely aged samples before the AC voltage was applied. Despite being subjected to the same DC voltage, the flashover phenomenon did not occur in three other samples aged to different degrees. Large-amplitude discharges were found to appear earlier in the severely aged samples. At the same creepage discharge stage, as the aging time of the oil-paper increased, the number of large-amplitude discharges was found to rapidly increase, and the time interval between adjacent discharges was found to gradually decrease. At each stage of the creepage discharge, the small-amplitude discharge has a “hump” shaped distribution. The larger the DC voltage component, the shorter the endurance time of aged oil-paper, and the more severe the damage to the oil-paper. The DC voltage component was found to have an accelerating effect on the development of creepage discharge in aged oil-paper insulation.

Enhancing paper hydrophobicity is of key importance for many paper-based applications. Fatty acids or vegetable oils and their derivatives replace environmentally harmful conventional coating materials but still require challenging chemical reactions for covalent attachment onto paper. Here, we show that simple storage of olive oil-coated cotton linter paper at 70 °C and subsequent Soxhlet extraction is able to endow paper with hydrophobic properties, reaching water contact angles above 130°. In-depth chemical and morphological analytics show the relevance of temperature and air accessibility during the aging process compared with aging at ambient temperature and under the exclusion of oxygen, underlining the importance of assessing a coating's long-term performance and stability under diverse storage conditions. Simple storage of vegetable oil-coated paper at elevated temperatures followed by extraction proves to be an easy way to produce stable covalently attached hydrophobic paper coatings with exceptionally low coating amounts. [ABSTRACT FROM AUTHOR]

The aging and acidification behavior of paper archives affect their long-term preservation. Therefore, delaying or preventing aging and acidification has become an important topic in the field of paper archives management. the aging and acidification behavior of commercial archival paper were studied by measuring pH value, electrical conductivity, mechanical properties and whiteness in this work. The results show that the aging and acidification phenomena are obvious after dry-heat aging treatment. The molecular degradation of cellulose, hemicellulose, lignin and other components results in the decrease of pH value of the system, which decrease with the increase of the treatment temperature and time. The electrical conductivity of the system increases because of the molecular degradation and structural degradation, and with the increase of the treatment temperature and time, the electrical conductivity increases more significantly. After aging treatment, the paper appears etching and increasing microcosmic pores. With the occurrence of molecular degradation and structural degradation, the tensile index and whiteness of the paper decrease, and with the increase of the treatment temperature and time, the tensile index and whiteness decrease more significantly. [ABSTRACT FROM AUTHOR]

The aging process of paper will be accelerated by acidification behavior during the storage process of paper archives, and the mechanical properties of paper archives will be weakened. By deacidizing and strengthening, the further aging of the acidified archives paper can be delayed or prevented, and the mechanical properties can be improved, so that the service life of paper archives is prolonged. To delay even to prevent the aging process, deacidizing and strengthening technology is employed. Herein, the "hybrid" system was reported by combining nano-calcium carbonate as deacidification agent, modified hydroxypropyl cellulose as reinforcement agent and ethanol as dispersant. The artificially acidified paper was brushed with it, and the pH value, mechanical properties and whiteness were measured to study the effect of deacidification and reinforcement. The results showed that oleic acid was successfully grafted onto hydroxypropyl cellulose by N,N′-carbonyl diimidazole mediated method to obtain oleic acid grafted hydroxypropyl cellulose with good dispersion in ethanol. After treating acidified paper with "hybrid" system, the pH value and the tensile strength index increase, the whiteness is almost unchanged, that is, the use of "hybrid" system plays a good deacidifying strengthening effect. The acidified paper samples before and after treatment with "hybrid" system were subjected to dry-heat aging treatment. Compared with acidified paper, the pH value, tensile strength index and whiteness of acidified paper treated with "hybrid" system are effectively inhibited, that is, the use of "hybrid" system can effectively delay the aging and acidification process of paper. [ABSTRACT FROM AUTHOR]

This article adds more information to the problem of natural ester use as an electroinsulating fluid in cellulose paper-oil systems, e.g., for use in power transformers. An accelerated thermal aging (120, 140 and 160 °C) of samples consisting of cellulose paper (transformerboard), a treated natural ester (filtered, basic Al2O3, 0.53% DBPC), a copper plate and moisture was studied. Research was especially focused on the impact of moisture on the aging of the above system. Samples with three different oil moisture levels (80, 143 and 305 ppm water content) were subjected to thermal aging to display the change in a selection of properties (tanδ, acid number, water content). For a study of the polarization effects, broadband dielectric spectroscopy (BDS) was performed to observe the complex permittivity and conductivity dependencies on the temperature and frequency (±30 °C, 0.01-107 Hz). Havriliak-Negami (H-N) diagrams were used to further understand the results. The degradation products during thermal aging were recognized by Fourier transform infrared (FT-IR) spectroscopy. Hydrolysis and hydrogenation occurred in the insulating system with a natural ester aged by elevated temperatures, which is in contrast to CO2 formation in the case of electric aging. The results showed an increase in the acid number, dissipation factor, and number of hydrolysis and hydrogenation products. Furthermore, changes in polarization were observed as a consequence of the thermal aging of paper-natural ester insulation system with the presence of copper and moisture.

Fluorescence is well-known nowadays as one of the most efficient anti-counterfeiting techniques. Zinc oxide quantum dots (ZnOQds) are exceptionally fluorescence when exposed to ultraviolet (UV) light, which makes them a candidate for anti-counterfeiting printing. The resulting anti-counterfeiting papers are sustainable and resistance against organic dyes. In this work, ZnOQds were prepared via a green method and characterized under UV–visible spectroscopy, along with microscopic observations by transmission electron microscopy (TEM) and crystallography by X-ray diffraction (XRD). Formation of ZnOQds nanocrystals with an average partials size of 7.3 nm was approved. Additionally, double-layers sheets were prepared at two loading concentrations of ZnOQds, namely 0.5 and 1 (wt./v) and underwent characterization using a topographical surface study via field emission scanning electron microscopy (FE-SEM). Hybrid sheets were mechanically more stable compared to single-layer paper and likewise polymer film. Moreover, aging simulation approved a high stability for hybrid sheets. Particularly, the photoluminescence emission affirmed anti-aging character of hybrid paper for more than 25 years. The hybrid sheets also showed a broad range of antimicrobial activity.

Aramid chopped fibers/polyphenylene sulfide (ACFs/PPS) composite paper exhibits great potential for application in several cutting‐edge areas because of their excellent comprehensive properties. However, the mechanism underlying thermal aging and the role it plays in the performance of ACF/PPS composite paper remain poorly characterized. Herein, we studied the change in the chemical structure of ACFs/PPS composite paper during thermal oxidative aging and investigated the correlation between the evolution of chromophore/auxochrome groups and the development of color appearance in the ACFs/PPS composite paper. Using the color space theory, we established a correlation model among the degrees of thermal aging, the evolution of color appearance, and the changes in the mechanical properties of ACFs/PPS composite paper. On the basis of this model, the degree of aging and the corresponding mechanical strength of ACFs/PPS composite paper under different conditions could be rapidly received by estimating the change in color factor only. This study sheds new light on elucidates and provides a method for the study of polymer thermal oxidative aging. [ABSTRACT FROM AUTHOR]

The paper presents the results of research and analysis of literature data on the paper insulation's thermal aging. An exponential decrease in the degree of polymerization of paper insulation from the aging time is established, at the starting time of transformers’ operation the aging rate of paper insulation is maximal and after that its slowing down. It was found out that the degree of polymerization at the starting time of the transformer's operation can be in the range of 900 units, this is due to its drying during the manufacturing process.

In order to determine the influence of bast fibers isolated from Wikstroemia bark on the durability of paper, self-made paper was prepared using bagasse pulp mixed with Wikstroemia bark pulp using Kaihua paper manufacturing technology. The durability properties of the paper obtained with different proportions of Wikstroemia bark pulp were measured and analyzed. The results showed that Wikstroemia bark can lower the acidity, improve the mechanical strength, and delay the aging of paper. The mechanical strength showed an exponential relationship with the amount of Wikstroemia bark pulp added to the paper pulp. There was a linear positive correlation between the initial polymerization degree of the paper and the amount of Wikstroemia bark pulp, while the molecular fracture rate of the paper with Wikstroemia bark pulp was considerably reduced. Wikstroemia bark fibers are long fibers with high strength. At the same time, Wikstroemia bark fibers differ greatly in length, so the uniformity can meet the requirements. The durability of the paper made from only bagasse pulp was poor, but the overall strength and polymerization degree of the paper improve after being mixed with Wikstroemia bark pulp. [ABSTRACT FROM AUTHOR]

Embodied theories of cognition consider many aspects of language and other cognitive domains as the result of sensory and motor processes. In this view, the appraisal and the use of concepts are based on mechanisms of simulation grounded on prior sensorimotor experiences. Even though these theories continue receiving attention and support, increasing evidence indicates the need to consider the flexible nature of the simulation process, and to accordingly refine embodied accounts. In this consensus paper, we discuss two potential sources of variability in experimental studies on embodiment of language: individual differences and context. Specifically, we show how factors contributing to individual differences may explain inconsistent findings in embodied language phenomena. These factors include sensorimotor or cultural experiences, imagery, context-related factors, and cognitive strategies. We also analyze the different contextual modulations, from single words to sentences and narratives, as well as the top-down and bottom-up influences. Similarly, we review recent efforts to include cultural and language diversity, aging, neurodegenerative diseases, and brain disorders, as well as bilingual evidence into the embodiment framework. We address the importance of considering individual differences and context in clinical studies to drive translational research more efficiently, and we indicate recommendations on how to correctly address these issues in future research. Systematically investigating individual differences and context may contribute to understanding the dynamic nature of simulation in language processes, refining embodied theories of cognition, and ultimately filling the gap between cognition in artificial experimental settings and cognition in the wild (i.e., in everyday life).

Given the key roles of the cerebellum in motor, cognitive, and affective operations and given the decline of brain functions with aging, cerebellar circuitry is attracting the attention of the scientific community. The cerebellum plays a key role in timing aspects of both motor and cognitive operations, including for complex tasks such as spatial navigation. Anatomically, the cerebellum is connected with the basal ganglia via disynaptic loops, and it receives inputs from nearly every region in the cerebral cortex. The current leading hypothesis is that the cerebellum builds internal models and facilitates automatic behaviors through multiple interactions with the cerebral cortex, basal ganglia and spinal cord. The cerebellum undergoes structural and functional changes with aging, being involved in mobility frailty and related cognitive impairment as observed in the physio-cognitive decline syndrome (PCDS) affecting older, functionally-preserved adults who show slowness and/or weakness. Reductions in cerebellar volume accompany aging and are at least correlated with cognitive decline. There is a strongly negative correlation between cerebellar volume and age in cross-sectional studies, often mirrored by a reduced performance in motor tasks. Still, predictive motor timing scores remain stable over various age groups despite marked cerebellar atrophy. The cerebello-frontal network could play a significant role in processing speed and impaired cerebellar function due to aging might be compensated by increasing frontal activity to optimize processing speed in the elderly. For cognitive operations, decreased functional connectivity of the default mode network (DMN) is correlated with lower performances. Neuroimaging studies highlight that the cerebellum might be involved in the cognitive decline occurring in Alzheimer's disease (AD), independently of contributions of the cerebral cortex. Grey matter volume loss in AD is distinct from that seen in normal aging, occurring initially in cerebellar posterior lobe regions, and is associated with neuronal, synaptic and beta-amyloid neuropathology. Regarding depression, structural imaging studies have identified a relationship between depressive symptoms and cerebellar gray matter volume. In particular, major depressive disorder (MDD) and higher depressive symptom burden are associated with smaller gray matter volumes in the total cerebellum as well as the posterior cerebellum, vermis, and posterior Crus I. From the genetic/epigenetic standpoint, prominent DNA methylation changes in the cerebellum with aging are both in the form of hypo- and hyper-methylation, and the presumably increased/decreased expression of certain genes might impact on motor coordination. Training influences motor skills and lifelong practice might contribute to structural maintenance of the cerebellum in old age, reducing loss of grey matter volume and therefore contributing to the maintenance of cerebellar reserve. Non-invasive cerebellar stimulation techniques are increasingly being applied to enhance cerebellar functions related to motor, cognitive, and affective operations. They might enhance cerebellar reserve in the elderly. In conclusion, macroscopic and microscopic changes occur in the cerebellum during the lifespan, with changes in structural and functional connectivity with both the cerebral cortex and basal ganglia. With the aging of the population and the impact of aging on quality of life, the panel of experts considers that there is a huge need to clarify how the effects of aging on the cerebellar circuitry modify specific motor, cognitive, and affective operations both in normal subjects and in brain disorders such as AD or MDD, with the goal of preventing symptoms or improving the motor, cognitive, and affective symptoms. [ABSTRACT FROM AUTHOR]

There is a growing interest in examining alterations in telomere length as a reliable biomarker of general health, as well as a marker for predicting later morbidity and mortality. Substantial evidence shows that telomere length is associated with aging; telomere shortening acts as a “counting mechanism” that drives replicative senescence by limiting the mitotic potential of normal (but not malignant) cells. In this Correspondence, we attempt to answer the question of why recently published papers about telomere length alterations increase our uncertainty rather than reduce it. This discussion includes three major research areas regarding telomere length: environmental stressors, aging, and life span. Our review suggests that activation of telomerase activity due to stressors in space might be a double-edged sword with both favorable and unfavorable consequences. The selection of an effect’s consequence must clearly elucidate the experimental conditions as well as associated stressors. In this Correspondence, we attempt to answer the question of why recently published papers about telomere length alterations increase our uncertainty rather than reduce it. The selection of an effect’s consequence must clearly elucidate the experimental conditions as well as associated stressors. Both positive and negative consequences must be clearly addressed in order to bolster the conclusions, as well as identify future research directions.

• Magnesium oxyhydroxide colloid was obtained by pulsed laser ablation of Mg in water. • Magnesium oxyhydroxide lamellas effectively bind to the surface of the paper fibers. • Magnesium oxyhydroxide colloid treatment bleaches, hardens and stabilizes the paper. • The treatment proposed is highly effective and surpasses the conventional techniques. Magnesium-containing nanocolloids were synthesized by nanosecond pulsed laser ablation (PLAL) of a Mg target in water. As-prepared colloids contained 2-D lamellar nanostructures of magnesium oxyhydroxide Mg 5 O(OH) 8 (Mg-NSs) with a thickness of 5–10 nm and a length/width up to one micron. The colloids obtained were used for the first time to restore old, low-quality paper (a Russian book from the beginning of the 20th century). All results were compared to conventional treatment with basic magnesium carbonate. It was found that Mg-NSs facilitated effective deacidification and conservation treatment of the paper. Paper pH increased after treatment and remained stable upon artificial aging. Moreover, treatment led to an increase in paper whiteness of up to 10% and paper strengthening up to 25%. In general, the treated paper became more resistant to the deterioration processes during aging. Thus, colloid of Mg 5 O(OH) 8 lamellar nanostructures obtained by PLAL in water is a promising agent for paper restoration and conservation. [ABSTRACT FROM AUTHOR]

Abstract Historical papers are often locally damaged by exogenous influences and/or have endogenously degraded paper areas. The stabilization of such papers is very important because further use of the object can cause additional damage. Different types of nanocellulose are interesting as a novel stabilizing materials for paper due to their close structural relation to the paper matrix. Therefore, the present study investigated whether the treatment of historical papers with nanocellulose suspensions is a novel method for paper stabilization. Two different types of nanocelluloses, bacterial cellulose and a mechanically nanofibrillated cellulose based on wood pulp, were tested with regard to their performance in stabilizing fragile papers. Concerning material handling and application in conservation steps, different ways to modify the suspensions were tested. The resulting suspensions were applied to historical papers from several centuries with different extents of damage. The paper-nanocellulose composites were characterized with regard to their optical and microscopic integrity and by physical and chemical analyses. The treatment of mechanical damage and the consolidation of weakened paper areas could be realized by the application of a nanocellulose suspension without an additional adhesive. The results of the treatment depend on the type of nanocellulose, on the paper material, on processing and application techniques. The paper discusses the applicability and stability of the differently prepared nanocellulose suspensions, also with regard to their mode of application and long-term performance. Advantages and limitations are addressed in detail. Graphical abstract Bacterial nanocellulose and nano-fibrillated cellulose from pulp can be used to consolidate damaged historic papers without the application of additional adhesives

The vast majority of power transformers have an insulation system consisting of both insulating mineral oil and Kraft paper. The principal oil degradation agents are oxygen and temperature, whereas the main mechanisms of insulating Kraft paper degradation are water and acids (acidic hydrolysis degradation), temperature (pyrolytic degradation), and oxygen (oxidative degradation). [ABSTRACT FROM AUTHOR]

This study conducts thermal aging treatment to study the effect of thermal aging on the PD degradation process of the oil-paper insulation. The partial discharge inception voltages, extinction voltages, carbon mark, and microscopic morphology of samples are analyzed. The results show that thermal aging does not reduce the partial discharge inception voltages of oil-paper but can make the spark produced in the oil-paper more difficult to extinguish. At the initial stage, thermal aging has little effect on the development of partial discharge in normal direction of samples, while in later stages, the effect begins to appear; thermal aging reduces the insulation performance between layers of oil impregnated paper and accelerates the carbon trace growth rate in the horizontal direction. In this model, the first layer is most severely bombarded by electrons, and this layer is most obviously affected by the electric field in the normal direction at the contact point between the electrode and the insulating paper. The lower layer is affected by the horizontal and vertical electric fields; therefore, a large area of fiber looseness occurs on the surface of the oil impregnated paper. The degree of deterioration is proportional to the endurance time and aging time, and the damage degree of oil impregnated paper decreases with the increase of the number of layers. [ABSTRACT FROM AUTHOR]

The oil-impregnated dielectric papers are the main components of distribution transformer which govern its service time. Therefore, durability enhancement of this grade of paper will cause to extend transformers life. Hence in this research long fiber unbleached Kraft pulp and mixture of it with bagasse soda pulp with the ratio of 20% to 80% were used to make oil-impregnated dielectric papers with the grammage of 60 g/m2. The effect of dicyandiamide application with different content in paper structure and thermal aging were then assessed on dielectric properties and tensile strength of the insulation papers. The results showed that with increasing dicyandiamide content, the capacitance and tensile strength index decreased in comparison with untreated samples, but dielectric loss, insulation resistance, and breakdown voltage were improved. However, slight changes were observed in most dielectric properties during aging, but dicyandiamide caused to prevent loss of the tensile strength of insulated papers. Generally it could be concluded that dicyandiamide acts efficiently in thermal stabilization of insulation paper exposed to aggressive conditions inside the oil-filled transformer.

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Paper-based diagnostics provide a low-cost, reliable and easy to use mode of blood typing. The shelf-life of such products, however, can be limited due to the reduced activity of reagent antibodies sorbed on the paper cellulose fibers. This study explores the effects of aging on antibody activity for periods up to 12 months on paper and in solution under different aging and drying conditions—air-dried, lyophilized, and kept as a liquid. Paper kept wet with undiluted antibody is shown to have the longest shelf-life and the clearest negatives. Antibody diluted with bovine serum albumin (BSA) protects against the lyophilization process, however, beyond 9 months aging, false positives are seen. Paper with air-dried antibodies is not suitable for use after 1 month aging. These results inform preparation and storage conditions for the development of long shelf-life blood grouping paper-based diagnostics.

Abstract: Paper is still regarded as the most common carrier of information. Encouraged by environmental policies, the papermaking technology recently changed, resulting in an increased production of recycled paper. Two types of contemporary paper, non-recycled and recycled, were thus investigated to evaluate possible differences in their rate of degradation. The analyses were carried out using unaged paper to evaluate acidity, dry matter and ash content, lignin presence, and fibre furnish. Accelerated ageing experiments were performed at different temperatures (50-80 °C) and water vapour pressures (90.5-227.5 torr). Viscometric measurements were carried out to evaluate the extent of paper degradation as a function of time, upon various accelerated ageing conditions. The results indicate that the rates of degradation follow first-order kinetics with respect to scission of glycosidic bonds, the rate constants for recycled paper being found to be slightly higher than the corresponding constants for non-recycled paper, but comparable within experimental limits. The kinetic constants did not display a monotonic trend with increasing water vapour pressures. The Arrhenius dependence of the rate constants on temperature for both kinds of paper supplied the activation energies, which fall in the typical range expected for paper degradation. Finally, the measured rate constants fit fairly well the recently modelled dose-response function for historic paper. Colour changes were found to be visible to the human eye for samples aged for more than 40 days at 60, 70 and 80 °C.Graphical abstract: [ABSTRACT FROM AUTHOR]

The moisture-induced degradations during the use of paper are of growing concern for the existing paper materials stored in libraries, archives and museums. Knowing the moisture profiles is therefore a primary step in order to understand paper deterioration and give an assessment of degradation rate of library collections in their preservation. In this paper, the theoretical models based on 2-D scanning electron microscope real image microstructure were established for describing moisture transport in paper sheet in response with external humidity and the moisture diffusion profiles. The acid-catalyzed hydrolysis kinetic in combination with moisture diffusion theory gave the complementary explanation for the time-dependent natural aging process of a paper sheet and book stacks. The differential equations were solved by a numerical approach based on the finite element method implemented in commercial COMSOL Multiphysics. The 2-D simulation results, with a mesh based directly on SEM characterization of microstructure, could show the equilibrium moisture contents and the degradation rates as a function of relative humidity in cellulose pores and cellulose fibers across the transverse section of paper. For the stacks composed of books, the air gaps between the books provided convenient channels for diffusion and transport, accelerating the moisture transport process in the book stacks. [ABSTRACT FROM AUTHOR]

This paper investigates the behavior of interface charges between oil and oil immersed paper insulations in unaged and aged samples. Combined accelerated thermal and electrical aging experiments of oil immersed paper insulations are conducted to obtain aged oil and aged paper samples. The interface charges between oil and paper samples with different aging status are measured with the Pulsed Electro-acoustic (PEA) method. Zeta potentials in samples with different aging status are determined. It is shown that the amount of interface charge increases with the aging duration, and does not follow the prediction of Maxwell-Wagner-Sillars (MWS) law. This is explained in terms of the increase of the interface charge barrier due to the effect of electric double layer. It is proposed that interface charge may act as an optional characterization parameter for the assessment of oil immersed paper insulations. [ABSTRACT FROM AUTHOR]

The application of vibration-based condition monitoring methods to power transformers has shown the potential for detecting mechanical transformer failures. The ageing of winding insulation paper, which is a common problem in long-serving power transformers, affects both the electrical and mechanical strength of the windings. This paper is concerned with the vibration features of winding disks with aged insulation paper. The vibration characteristics of single-layer winding disks wrapped with insulation paper are investigated. By examining the vibration frequency responses of winding disks with different degrees of ageing of insulation paper, the effects of aged paper on the vibration behaviors of winding disks are demonstrated. The experimental results show that changes in the vibration responses of winding disks can be related to the ageing of insulation paper, and thus it is possible to detect this failure mode in a power transformer using a vibration-based method. A qualitative explanation for these changes is presented, using the degradation of the mechanical strength of the insulation paper. [ABSTRACT FROM AUTHOR]

The long-term operation of dry-type transformer bushings at high temperatures can impact the performance of their primary insulation material. This article presents an experimental study of the effect of thermal aging time on electrical treeing in the epoxy resin-impregnated paper. The experimental results show that the electrical treeing pattern along the middle path of the electric field and the interlayer creepage along the average direction of the electric field are closely related to the aging time. Under the effect of thermal aging at 150 °C, the tree-starting voltage of epoxy resin-impregnated paper tends to increase and decrease as the aging time increases. An analysis and discussion of the test results in conjunction with scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) tests suggest that the destruction of the cross-linked network of the epoxy resin-impregnated paper at 150 °C is a fundamental reason for the significant decrease in the material’s tree-starting voltage and the change in electrical treeing morphology and interlayer creepage. Long-term operation at high temperatures can seriously impact the primary insulation performance of dry-type transformer bushings and requires attention. [ABSTRACT FROM AUTHOR]

The generation and distribution of furfural are significantly affected by moisture content in the insulating paper. However, the diffusion mechanism of furfural under moisture effect is not clear, hence, this study investigates the effect of moisture on the diffusion characteristics of furfural by combining macro experiment and micro molecular dynamics simulation. The simulation results demonstrate that the increased moisture content in paper accelerates the diffusion of furfural from paper to oil, which is also proved by the experimental data. Then, the results of interaction energy analysis indicate that the increase of moisture enhances the van der Waals force between oil and furfural. The present findings are expected to improve the theoretical level of furfural analysis, which will facilitate the aging evaluation of the transformer insulating paper based on furfural. [ABSTRACT FROM AUTHOR]

The mechanical performance of two commercial papers used as solid insulation in power transformers, namely standard Kraft and a thermally upgraded Kraft paper, were studied during accelerated aging in Luminol oil at 170 ?C. The results show a relationship between the degree of polymerization and the mechanical properties measured by tensile testing. A linear relationship was found between the mechanical properties of paper, the tensile index (Tidx), and the concentration of methanol present in the oil. The methanol chemical marker has been proven to be an accurate assessment tool for the aging of cellulosic paper. The results show a promising tool for correlating the methanol concentration in oil, as an indirect indicator, with the mechanical performance of the paper. This approach can be used to monitor the real state of the cellulose chains in the power transformer insulation paper. [ABSTRACT FROM AUTHOR]

Furfural content in oil is widely accepted as an effective parameter to mirror aging of insulation paper. However, pressboards are also abundant in transformers, which are always neglected in furfural analysis. Different masses of insulation paper and pressboard produce different amounts of furfural during the aging process. Thus, the furfural content in oil may differ in systems with different oil-paper-pressboard mass ratios. To address this problem, accelerated thermal aging experiments and furfural equilibrium experiments with different oil-paper-pressboard mass ratio systems were conducted under laboratory conditions. Furfural contents in oil, paper, and pressboard were measured. In a simplified oil-paper system, the furfural content in oil differs in systems with different oil-paper mass ratios. Further analysis shows the furfural amount produced by 1 g insulation paper is the same with good repeatability in groups with different mass ratios. Different oil-paper mass ratios change the distribution coefficient of furfural between oil and paper, and an increase in the mass of insulation paper leads to more furfural remaining in the insulation paper. The pressboards in field transformers produce little furfural during the aging process, but absorb part of the furfural from oil, which decreases the furfural content in oil. Therefore, more pressboard in an oil-paper-pressboard system indicates lower furfural content in oil. An increase in insulation paper in the oil-paper-pressboard system causes a decrease in the effect of pressboard on furfural content in oil. [ABSTRACT FROM AUTHOR]

Vegetal oils are considered a suitable substitute for mineral oil that is widely used in power transformers as insulation and cooling medium. Due to the fact that more and more power transformers containing this alternative insulating fluid are being constructed a mathematical ageing models is needed to help predict transformer failures. The continued performance of power transformers depends on the condition of its paper insulation mainly. In this sense, this paper analyses Kraft paper degradation through the loss of its mechanical strength. Accelerated thermal ageing test of the paper in two different vegetal oils were carried out at three temperatures during diverse periods of time, in order to obtain information on the kinetics of the ageing degradation of the paper. The evolution of the mechanical properties of paper failure are analysed as a function of temperature and ageing time. In addition, the results obtained are compared with the traditional method of degradation analysis, based on the measurement of the degree of polymerisation. [ABSTRACT FROM AUTHOR]

The life expectancy of a transformer is closely related to the ageing state of its paper insulation. This paper presents novel markers for ageing characterization of paper insulation in oil-filled transformers based on the dispersion staining colors of cellulose fibres. Accelerated thermal ageing experiments were performed for oil-paper specimens at 120 and 130 °C to obtain aged oil-paper samples of different ageing degrees. The average degree of polymerization (DP), crystallinity index, and refractive index of insulation paper were measured; the experimental results show that an increase in refractive index of insulation paper was observed with the increase of ageing degree. Meanwhile, the dispersion staining colors of cellulose fibres in oil were observed using dispersion staining method; the experimental results show that the refractive index of cellulose fibres detached from insulation paper increases with the increment of ageing degree of insulation paper. Finally, two ageing markers—that is, the primary color ratio-based ratio of blue to red and the primary color ratio-based Mahalanobis distance were presented. Their relationship with DP and ageing time of insulation paper were obtained, and were compared with the corresponding relationship with 2-furaldehyde (2-FAL) and carbon oxides. The proposed ageing markers demonstrate an advantage over 2-FAL and carbon oxides and show potential in ageing state evaluation and residual life prediction of paper insulation in transformers. [ABSTRACT FROM AUTHOR]

The space charge effect of transformer insulating paper will distort its internal electric field, and its space charge effect will be more prominent under extremely complex working conditions. At present, the micromechanism of charge transport and electric field distortion characteristics of paperboard are not clear under complex working conditions. So in this article, based on the bipolar carrier transport (BCT) model and the dynamic carrier balance model, the effects of high temperature, aging degree, moisture content, and bent degree on charges accumulation in paperboard are studied under dc high voltage by numerical simulation and the measured data needed for simulation. The results show that the higher temperature strengthens the carrier migration, deepens the injection depth of the charge, and aggravates the distortion of electric field intensity in paperboard. The more extended the aging time of paperboard, the greater the internal trap density and the deeper the trap depth, which lead to charges migration difficultly. Increasing water content in the paperboard will accelerate space charges to reach a steady state, while further increasing it will slow down this process, which is related to the shallow trap getting deeper. When the critical part of paperboard is extruded, many traps are introduced, resulting in charges accumulation seriously. The research results can reference the design of paperboard and the maintenance of transformer insulation system. [ABSTRACT FROM AUTHOR]

This paper focuses on the in-depth analysis of the physical mechanism of the broadband frequency domain spectroscopy of oil-paper insulation. The complex permittivity shows two low-frequency dispersion phenomena, and the real part of the complex conductivity exhibits two slope changes under the synergistic effect of aging and moisture. The two slope changes are mainly attributed to the migration characteristics of water molecules and polar aging products with a degradation of the oil-paper insulation, resulting in the transition of the frequency dependence between the DC conductivity and AC conductivity. When the oil-paper insulation deteriorates seriously, the imaginary part of the dielectric modulus shows double relaxation peaks. Physical models of parasitic capacitance and molecular polarity interface polarization are proposed to reveal the physical mechanism of the double relaxation peaks. The left peak of the double relaxation peaks is caused by the accumulation of water molecules and polar aging products at the electrode/insulation interface, and the right peak is due to the charge disturbance of the cellulose molecular chain surface. This paper can provide theoretical support and technical guidance for the condition diagnosis and evaluation of oil-paper insulation. [ABSTRACT FROM AUTHOR]