Generating Static Fluid Spheres by Conformal Transformations

We generate an explicit four-fold infinity of physically acceptable exact perfect fluid solutions of Einstein's equations by way of conformal transformations of physically unacceptable solutions (one way to view the use of isotropic coordinates). Special cases include the Schwarzschild interior solution and the Einstein static universe. The process we consider involves solving two equations of the Riccati type coupled by a single generating function rather than a specification of one of the two metric functions.Comment: 4 pages revtex4, two figures, Final form to appear in Phys. Rev.

Sumptuary Synergy: British Imperialism Through the Tartan and Slave Trades

Sumptuary laws have been a useful tool for various national powers in regulating subjects and to promote class differentiation and business interests. The genesis of this study was one such law, entitled the South Carolina Negro Act of 1735, stipulating that slave garments could only be made of low-quality textiles. These fabrics were reflective of slaves living in chattel environments, thus also representing a slave’s status in society. This law forbade slaves from wearing “any sort of garment or apparel whatsoever, finer, other or of greater value than Negro cloth, duffels, coarse kerseys, osnabrigs, blue linen, check linen, or coarse garlix, or calicoes, checked cottons or Scottish plaids.” As most of the textiles listed in the law were somewhat generic and manufactured in several places, it was interesting to the authors that those who crafted the law were more specific to incorporate “Scottish plaids” as one of the acceptable textiles for slave clothing. Textiles were one of the pillars of England and colonial America’s slave trading economy. In fact, the American Colonies had become one of England’s greatest customers, as they represented a distinct piece of what has been termed the “Triangular Trade.” Gold bullion and manufactured goods left England bound for India’s textile manufacturing centers and also to Western Africa’s slave trading centers. These economic inputs provided the fuel necessary to procure goods, such as, inexpensive Indian Madras textiles and humans/slaves, which would then leave India and Africa bound for the plantations of the United States and Caribbean islands. Ships returning from the Americas to England would then supply raw materials, such as sugar and cotton, to fuel English industries, thus completing the cycle. By 1773, America would consume approximately one quarter of products that were made in England

Sumptuary Synergy: British Imperialism Through the Tartan and Slave Trades

Sumptuary laws have been a useful tool for various national powers in regulating subjects and to promote class differentiation and business interests. The genesis of this study was one such law, entitled the South Carolina Negro Act of 1735, stipulating that slave garments could only be made of low-quality textiles. These fabrics were reflective of slaves living in chattel environments, thus also representing a slave’s status in society. This law forbade slaves from wearing “any sort of garment or apparel whatsoever, finer, other or of greater value than Negro cloth, duffels, coarse kerseys, osnabrigs, blue linen, check linen, or coarse garlix, or calicoes, checked cottons or Scottish plaids.” As most of the textiles listed in the law were somewhat generic and manufactured in several places, it was interesting to the authors that those who crafted the law were more specific to incorporate “Scottish plaids” as one of the acceptable textiles for slave clothing. Textiles were one of the pillars of England and colonial America’s slave trading economy. In fact, the American Colonies had become one of England’s greatest customers, as they represented a distinct piece of what has been termed the “Triangular Trade.” Gold bullion and manufactured goods left England bound for India’s textile manufacturing centers and also to Western Africa’s slave trading centers. These economic inputs provided the fuel necessary to procure goods, such as, inexpensive Indian Madras textiles and humans/slaves, which would then leave India and Africa bound for the plantations of the United States and Caribbean islands. Ships returning from the Americas to England would then supply raw materials, such as sugar and cotton, to fuel English industries, thus completing the cycle. By 1773, America would consume approximately one quarter of products that were made in England

Reliability and cultural applicability of the Greek version of the International Personality Disorders Examination.

BACKGROUND: The International Personality Disorders Examination (IPDE) constitutes the proposal of the WHO for the reliable diagnosis of personality disorders (PD). The IPDE assesses pathological personality and is compatible both with DSM-IV and ICD-10 diagnosis. However it is important to test the reliability and cultural applicability of different IPDE translations. METHODS: Thirty-one patients (12 male and 19 female) aged 35.25 ± 11.08 years, took part in the study. Three examiners applied the interview (23 interviews of two and 8 interviews of 3 examiners, that is 47 pairs of interviews and 70 single interviews). The phi coefficient was used to test categorical diagnosis agreement and the Pearson Product Moment correlation coefficient to test agreement concerning the number of criteria met. RESULTS: Translation and back-translation did not reveal specific problems. Results suggested that reliability of the Greek translation is good. However, socio-cultural factors (family coherence, work environment etc) could affect the application of some of the IPDE items in Greece. The diagnosis of any PD was highly reliable with phi >0.92. However, diagnosis of non-specfic PD was not reliable at all (phi close to 0) suggesting that this is a true residual category. Dianosis of specific PDs were highly reliable with the exception of schizoid PD. Diagnosis of antisocial and Borderline PDs were perfectly reliable with phi equal to 1.00. CONCLUSIONS: The Greek translation of the IPDE is a reliable instrument for the assessment of personality disorder but cultural variation may limit its applicability in international comparisons

The influence of ultrasonic pre-treatments on metal adsorption properties of softwood-derived biochar

Biomass-derived biochars are studied extensively because of their unique surface properties and efficiency in removing heavy metals from aqueous solution. Power ultrasound pre-treatments are interesting in this context, as they can make significant changes in the physicochemical characteristics of biomass. Herein, we studied their effect on adsorption characteristics of softwood biochar under different conditions of frequency, power, temperature and exposure time of ultrasound. The 40 kHz pre-treated samples exhibited around 0.3 to 0.65 mg/g increase in equilibrium adsorption capacity (Qe) which highly depends on the combination of power versus time and temperature of ultrasound. The isotherm and thermodynamic studies also showed that the mechanical effect of ultrasound plays a vital role in enhancing the surface. Results from this study demonstrated that ultrasound pre-treatment conditions influence the behaviour of biochar towards metal adsorption and ultrasonic pre-treatments can be used as an efficient processing method for biomass residues and the derived products. © 2020 Elsevier Lt

Enhanced activation of ultrasonic pre-treated softwood biochar for efficient heavy metal removal from water

Physical and chemical modification on biochar is an interesting approach to enhance the properties and make them potential candidates in adsorption of heavy metals from water. Studies have shown that ultrasound treatments as well as alkali activations on biochar has positive impact on adsorption behaviour of the material. Base activation on biochar derived from ultrasound pre-treated woodchips were studied to understand the influence of ultrasound pre-treatment on chemical modification of biochar and the adsorption properties emerged from it. 40 and 170 kHz ultrasound pre-treated softwood woodchips were subjected to laboratory scale pyrolysis and the resulted biochars were treated with NaOH. The physicochemical properties were examined, and the adsorption experiments revealed that ultrasound pre-treatment assisted biochars have better adsorption capacity as compared to untreated biochar samples after activation. 170 kHz pre-treated sample exhibited an equilibrium adsorption capacity of 19.99 mg/g which is almost 22 times higher than that of corresponding non-activated sample. The ultrasound pre-treated samples showed improved competitive adsorption behaviour towards copper ions in comparison with nickel or lead. The overall study suggests that ultrasound pre-treated biochars combined with alkali activation enhances the heavy metal removal efficiency and these engineered biochars can be used as an effective adsorbent in the field of wastewater treatment. © 2021 Elsevier Lt

Pre- and post-pyrolysis effects on iron impregnation of ultrasound pre-treated softwood biochar for potential catalysis applications.

Slow pyrolysis is widely used to convert biomass into useable form of energy. Ultrasound pre-treatment assisted pyrolysis is a recently emerging methodology to improve the physicochemical properties of products derived. Biochar, the solid residues obtained from pyrolysis, is getting considerable attention because of its good physicochemical properties. Various modification techniques have been implemented on biochars to enhance their properties. Ultrasonic pre-treated wood biochar has showcased efficient surface and adsorption properties. Iron impregnated biochar is interesting as it has potentially proved the efficiency as an efficient low-cost catalyst. In this study, by combining the advantages of ultrasonic pre-treatment and iron impregnation, we have synthesized a series of Fe-impregnated biochar from softwood chips. Pre- and post-pyrolysis methods using a lab-scale pyrolyser had been implemented to compare the pyrolysis product yields and degree of impregnation. Biochars derived from ultrasound pre-treated woodchips by post pyrolysis demonstrated better impregnation of Fe ions on surface with better distribution of pyrolysis products such as biochar and biogas. The surface functionality of all ultrasound pre-treated biochars remained the same. However, post-pyrolysed samples at high frequency ultrasound pre-treatment showed better thermal stability. The chemical characteristics of these modified biochars are interesting and can indeed be used as a cost-effective replacement for various catalytic applications

Trauma-related emotions and radical acceptance in dialectical behavior therapy for posttraumatic stress disorder after childhood sexual abuse

Background: Posttraumatic Stress Disorder (PTSD) related to childhood sexual abuse (CSA) is often associated with a wide range of trauma-related aversive emotions such as fear, disgust, sadness, shame, guilt, and anger. Intense experience of aversive emotions in particular has been linked to higher psychopathology in trauma survivors. Most established psychosocial treatments aim to reduce avoidance of trauma-related memories and associated emotions. Interventions based on Dialectical Behavior Therapy (DBT) also foster radical acceptance of the traumatic event. Methods: This study compares individual ratings of trauma-related emotions and radical acceptance between the start and the end of DBT for PTSD (DBT-PTSD) related to CSA. We expected a decrease in trauma-related emotions and an increase in acceptance. In addition, we tested whether therapy response according to the Clinician Administered PTSD-Scale (CAPS) for the DSM-IV was associated with changes in trauma-related emotions and acceptance. The data was collected within a randomized controlled trial testing the efficacy of DBT-PTSD, and a subsample of 23 women was included in this secondary data analysis. Results: In a multilevel model, shame, guilt, disgust, distress, and fear decreased significantly from the start to the end of the therapy whereas radical acceptance increased. Therapy response measured with the CAPS was associated with change in trauma-related emotions. Conclusions: Trauma-related emotions and radical acceptance showed significant changes from the start to the end of DBT-PTSD. Future studies with larger sample sizes and control group designs are needed to test whether these changes are due to the treatment. Trial registration: ClinicalTrials.gov, number NCT0048100

Enhancement of tensile properties of flax-mat epoxy composites via click chemistry with surface fibrillation and compaction of the fiber preforms

Abstract The mechanical properties of composite materials are strongly related to the fiber–matrix interface properties. This study focuses on the click chemistry modification of short flax fibers using the Cu(I)-catalyzed Huisgen cycloaddition type, to strengthen the fiber–fiber interface for composite applications. The flax fibers are functionalized in three steps: a mechanical fibrillation pre-treatment of the fibers surface, followed by a chemical cleaning treatment to eliminate pectin, lignin, hemicelluloses and waxes, allowing exposure of the hydroxyl groups in flax fibers in view of the final treatment of click chemistry. The chosen strategy allows the adaptation of propargylation and tosylation reactions to flax fibers in aqueous media. FTIR and EDX analysis of fibers treated at intermediate stages confirmed the presence of various surface functions of modified fibers with a very high degree of substitution. The properties obtained are strongly improved for reinforcements containing covalent fiber–fiber contacts. Tensile, tearing and bursting tests performed on dry mat reinforcements showed increases in the tensile index, elongation at break, tensile stiffness, burst and tear indexes of 519%, 355%, 201%, 304% and 421%, respectively. Resin transfer molding (RTM) was used to fabricate epoxy composites made of click chemistry-treated short fiber flax mats at a fiber volume content (Vf) of 40%. Tensile tests results showed the positive effect of the click chemistry treatment, with increases in the tensile modulus, strength and strain at break of 41.5%, 64.3% and 30.8%, respectively. Marked improvements in strength and Young's modulus were obtained for composites made of pre-compacted and cross-linked flax-mat preforms

Tensile properties improvement of a unidirectional-mat flax/epoxy composite via click chemistry, nanocellulose addition and surface refining of short mat fibres

Abstract The mechanical characteristics of natural fibre composites (NFCs) are closely linked to fibre-matrix and fibre-fibre interactions. This work investigates the improvement of tensile properties of a flax/epoxy composite through the application of click chemistry reaction to a unidirectional-mat (UDM) reinforcement with modifications made on the short fibre mat and unidirectional flax fibre phases of the reinforcement. The surface of short flax fibres was fibrillated to increase the accessibility of hydroxyl groups for all preliminary reactions and the final click chemistry cross-linking, which creates stable covalent triazole bonds between azide and alkyne groups. A small percentage of treated nanocellulose was incorporated to further enhance the reinforcement properties. FTIR and EDX analysis confirmed the presence of the various functional groups on the surface of nanocellulose and flax fibres with very high degrees of substitution. The treatment significantly improved the mechanical properties of the dry reinforcement, including a 220% mean increase in the tensile strength. However, the treatments, particularly the addition of nanocellulose, resulted in a reduction in the permeability to liquid resin of the reinforcements, highlighting the need for compromises in their manufacture. Nonetheless, marked improvements in tensile strength and Young’s modulus were obtained for composites made of pre-compacted and cross-linked fibre preforms. Increases in elastic modulus, strength and strain at break of up to 50.1%, 53.8% and 10.1% were obtained, respectively