Kinetics and mechanisms of solid-state phase transitions and reactions

The phase transition of C,a- to ^p-ferrosilicon has been studied, both with and without a doping of 1% aluminium, at high temperature by time-resolved simultaneous X-ray powder diffraction and iron K-edge EXAFS at four temperatures, and also by high temperature time-resolved Mossbauer spectroscopy at two temperatures. The extent of the phase transition and its evolution with time has been determined using a novel method. The results have been analysed in terms of theories of solid state kinetics. Some tentative conclusions for the mechanism of the phase transition have been drawn. Approximate values for the activation energy of the phase transitions, with and without 1% aluminium doping, have been derived. The structures of the phases, with and without 1% aluminium doping, have been examined by techniques including X-ray powder diffraction, Fe K-edge EXAFS and Si K-edge EXAFS and Mossbauer spectroscopy, in order to gain insight on how the presence of the dopant might affect the phase transition. The formation of mullite from precursors formed by the hydrothermal processing of aluminium- and silicon-acetates, both undoped and with the inclusion of iron and vanadium dopants, has been investigated using flat-plate room temperature X-ray powder diffraction of samples heated at a variety of temperatures and for different durations of time. The structures of the precursors and the mullite formed have been examined by techniques including X-ray powder diffraction, Fe K-edge EXAFS, Mossbauer spectroscopy and MAS NMR. The formation of 5% iron-doped mullite from a precursor formed by the hydrothermal processing of aluminium-, silicon- and iron acetates has also been monitored by time-resolved X-ray powder diffraction

Metacognitive Beliefs and Suicidal Ideation: An Experience Sampling Study

From MDPI via Jisc Publications RouterHistory: accepted 2021-11-19, pub-electronic 2021-11-24Publication status: PublishedThe current study aimed to examine the relationship between metacognitive beliefs about suicidal ideation and the content and process of suicidal ideation. This was to examine the potential contribution of the Self-Regulatory Executive Function (S-REF) model (Wells and Matthew, 2015) to suicidal ideation. Twenty-seven participants completed both trait and state-level measures of suicidal ideation, negative affect, defeat, hopelessness, entrapment and metacognitive beliefs. Experience Sampling Methodology (ESM) was adopted to measure state-level measurements with participants invited to complete an online diary up to seven times a day for six days. Multi-level modelling enabled a detailed examination of the relationships between metacognitive beliefs and suicidal ideation. Positive (β = 0.241, p 0.001) and negative (β = 0.167, p 0.001) metacognitive beliefs about suicidal ideation were positively associated with concurrent suicidal ideation even when known cognitive correlates of suicide were controlled for. The results have important clinical implications for the assessment, formulation and treatment of suicidal ideation. Novel meta-cognitive treatments targeting beliefs about suicidal ideation are now indicated. A limited range of characteristics reported by participants affects the generalizability of findings. Future research is recommended to advance understanding of metacognition and suicide but results demonstrate an important contribution of the S-REF model

Alkaloid production by a Cinchona officinalis "Ledgeriana" hairy root culture containing constitutive expression constructs of tryptophan decarboxylase and strictosidine synthase cDNAs from Catharanthus roseus

Cinchona officinalis ‘Ledgeriana’, former called Cinchona ledgeriana, hairy roots were initiated containing constitutive-expression constructs of cDNAs encoding the enzymes tryptophan decarboxylase (TDC) and strictosidine synthase (STR) from Catharanthus roseus, two key enzymes in terpenoid indole and quinoline alkaloid biosynthesis. The successful integration of these genes and the reporter gene gus-int was demonstrated using Southern blotting and the polymerase chain reaction. The products of TDC and STR, tryptamine and strictosidine, were found in high amounts, 1200 and 1950 mg g–1 dry weight, respectively. Quinine and quinidine levels were found to rise up to 500 and 1000 mg g–1 dry weight, respectively. The results show that genetic engineering with multiple genes is well possible in hairy roots of C. officinalis. However, 1 year after analyzing the hairy roots for the first time, they had completely lost their capacity to accumulate alkaloids.info:eu-repo/semantics/publishedVersio

Alkaloid production by a Cinchona officinalis "Ledgeriana" hairy root culture containing constitutive expression constructs of tryptophan decarboxylase and strictosidine synthase cDNAs from Catharanthus roseus

Cinchona officinalis ‘Ledgeriana’, former called Cinchona ledgeriana, hairy roots were initiated containing constitutive-expression constructs of cDNAs encoding the enzymes tryptophan decarboxylase (TDC) and strictosidine synthase (STR) from Catharanthus roseus, two key enzymes in terpenoid indole and quinoline alkaloid biosynthesis. The successful integration of these genes and the reporter gene gus-int was demonstrated using Southern blotting and the polymerase chain reaction. The products of TDC and STR, tryptamine and strictosidine, were found in high amounts, 1200 and 1950 mg g–1 dry weight, respectively. Quinine and quinidine levels were found to rise up to 500 and 1000 mg g–1 dry weight, respectively. The results show that genetic engineering with multiple genes is well possible in hairy roots of C. officinalis. However, 1 year after analyzing the hairy roots for the first time, they had completely lost their capacity to accumulate alkaloids.info:eu-repo/semantics/publishedVersio

Suspension cultured transgenic cells of Nicotiana tabacum expressing tryptophan decarboxylase and strictosidine synthase cDNAs from Catharanthus roseus produce strictosidine upon secologanin feeding

A transgenic cell suspension culture of Nicotiana tabacum L. ‘Petit Havana’ SR1 was established expressing tryptophan decarboxylase and strictosidine synthase cDNA clones from Catharanthus roseus (L.) G. Don under the direction of cauliflower mosaic virus 35S promoter and nopaline synthase terminator sequences. During a growth cycle, the transgenic tobacco cells showed relatively constant tryptophan decarboxylase activity and an about two- to sixfold higher strictosidine synthase activity, enzyme activities not detectable in untransformed tobacco cells. The transgenic culture accumulated tryptamine and produced strictosidine upon feeding of secologanin, demonstrating the in vivo functionality of the two transgene-encoded enzymes. The accumulation of strictosidine, which occurred predominantly in the medium, could be enhanced by feeding both secologanin and tryptamine. No strictosidine synthase activity was detected in the medium, indicating the involvement of secologanin uptake and strictosidine release by the cells.info:eu-repo/semantics/publishedVersio

Suspension cultured transgenic cells of Nicotiana tabacum expressing tryptophan decarboxylase and strictosidine synthase cDNAs from Catharanthus roseus produce strictosidine upon secologanin feeding

A transgenic cell suspension culture of Nicotiana tabacum L. ‘Petit Havana’ SR1 was established expressing tryptophan decarboxylase and strictosidine synthase cDNA clones from Catharanthus roseus (L.) G. Don under the direction of cauliflower mosaic virus 35S promoter and nopaline synthase terminator sequences. During a growth cycle, the transgenic tobacco cells showed relatively constant tryptophan decarboxylase activity and an about two- to sixfold higher strictosidine synthase activity, enzyme activities not detectable in untransformed tobacco cells. The transgenic culture accumulated tryptamine and produced strictosidine upon feeding of secologanin, demonstrating the in vivo functionality of the two transgene-encoded enzymes. The accumulation of strictosidine, which occurred predominantly in the medium, could be enhanced by feeding both secologanin and tryptamine. No strictosidine synthase activity was detected in the medium, indicating the involvement of secologanin uptake and strictosidine release by the cells.info:eu-repo/semantics/publishedVersio

An assay for secologanin in plant tissues based on enzymatic conversion into strictosidine

The secoiridoid glucoside secologanin is the terpenoid building block in the biosynthesis of terpenoid indole alkaloids. A method for its determination in plant tissues and in cell suspension cultures has been developed. This assay is based on the condensation of secologanin with tryptamine, yielding strictosidine, in a reaction catalysed by the enzyme strictosidine synthase (STR; E.C. 4.3.3.2). Subsequently, the formation of strictosidine is quantified by high performance liquid chromatography (HPLC). STR was isolated from transgenic Nicotiana tabacum cells expressing a cDNA-derived gene coding for STR from Catharanthus roseus. The high specificity of STR for secologanin, in combination with a sensitive and selective HPLC system, allows a simple extraction of secologanin from plant tissue. The detection limit of this method is 15 ng secologanin. Using this assay, secologanin contents were determined in tissues of various plant species; Lonicera xylosteum hairy roots were found to contain 1% of secologanin on a dry weight basis. # 1998 John Wiley & Sons, Ltd.info:eu-repo/semantics/publishedVersio

Northern Togo and the world economy

How global is the world economy? Does it also encompass the remote corners of the Third World where subsistence agriculture still predominates and where the first hard-surface roads have yet to be built? And if it does, when did these areas become incorporated into the world economy? Whereas by 1919 northernmost Togo had hardly any economic contacts with the outside world, the impact which the Great Depression had on it serves as evidence that only 10 years later this rural periphery had lost part of its former isolated, self-sufficient existence. Since then, capitalist penetration has made further inroads into the area. With most other Third-World ‘backwaters’ having experienced similar developments since the turn of the century, today's world economy does appear to be one globe-spanning, interdependent system

Oral prednisolone suppresses skin inflammation in a healthy volunteer imiquimod challenge model

Imiquimod (IMQ) is a topical agent that induces local inflammation via the Toll-like receptor 7 pathway. Recently, an IMQ-driven skin inflammation model was developed in healthy volunteers for proof-of-pharmacology trials. The aim of this study was to profile the cellular, biochemical, and clinical effects of the marketed anti-inflammatory compound prednisolone in an IMQ model. This randomized, double-blind, placebo-controlled study was conducted in 24 healthy volunteers. Oral prednisolone (0.25 mg/kg/dose) or placebo (1:1) was administered twice daily for 6 consecutive days. Two days after treatment initiation with prednisolone or placebo, 5 mg imiquimod (IMQ) once daily for two following days was applied under occlusion on the tape-stripped skin of the back for 48 h in healthy volunteers. Non-invasive (imaging and biophysical) and invasive (skin punch biopsies and blister induction) assessments were performed, as well as IMQ ex vivo stimulation of whole blood. Prednisolone reduced blood perfusion and skin erythema following 48 h of IMQ application (95% CI [−26.4%, −4.3%], p = 0.0111 and 95% CI [−7.96, −2.13], p = 0.0016). Oral prednisolone suppressed the IMQ-elevated total cell count (95% CI [−79.7%, −16.3%], p = 0.0165), NK and dendritic cells (95% CI [−68.7%, −5.2%], p = 0.0333, 95% CI [−76.9%, −13.9%], p = 0.0184), and classical monocytes (95% CI [−76.7%, −26.6%], p = 0.0043) in blister fluid. Notably, TNF, IL-6, IL-8, and Mx-A responses in blister exudate were also reduced by prednisolone compared to placebo. Oral prednisolone suppresses IMQ-induced skin inflammation, which underlines the value of this cutaneous challenge model in clinical pharmacology studies of novel anti-inflammatory compounds. In these studies, prednisolone can be used as a benchmark.</p