Search

Several classical writers had an impressive power of observation and often depicted medical conditions in their works long before medical literature did. Sleep paralysis is a common and frightening experience, in particular when occurring for the first time. Therefore, it is not surprising that it has been frequently described in the classical literature, eg by Dostoevsky, Kafka, Dickens, and Maupassant. In Nikolai Gogol's tale "The portrait" (1833) we could recognize an excellent description of a sleep paralysis, in which several components of this condition were depicted including motor paralysis, visual and auditory hallucinations, and autonomic manifestations. To the best of our knowledge, this account is the earliest description of a sleep paralysis in non-medical literature.

The effects of independent variables such as, temperature, concentration of ionic liquid (1-butyl-3-methyl-imidazolium hydrogen sulphate, [bmim][HSO 4 ]), chloride and sulphuric acid on copper extraction from chalcopyrite (CuFeS 2 ) ore were studied by surface optimization methodology. The Central Composite Face approach and a quadratic model were applied to the experimental design. The optimal copper extraction conditions given by the above methodology were 20% (v/v) of [bmim][HSO 4 ] in water, 100 g L −1 chloride, and 90 °C. The concentration of chloride and the temperature together exert a synergistic effect in enhancing chalcopyrite dissolution. Experimental data were fitted by multiple regression analysis to a quadratic equation and analyzed statistically. A model was developed for predicting copper extraction from CuFeS 2 ore with variables such as Cl − , [bmim][HSO 4 ], H 2 SO 4 concentrations and temperature in the range studied. The activation energy was calculated to be 60.4 kJ/mol (temperature range 30–90 °C), indicative of chemical control of the reaction and [bmim][HSO 4 ] acts as an acid in the reaction.

The preferential treatment of the aquaculture industry over fisheries and marine protected areas in Chile through the demarcation of the Areas Appropriate for Aquaculture has set it on a collision course with conservation, artisanal fishing and coastal communities. This article shows how marine democratic governance can evolve through the inclusion of artisanal fisher local ecological knowledge. Artisanal fishing communities elicit how contamination from industrial aquaculture is causing natural shellfish banks, fish populations and endangered cold corals to diminish. While fisheries and aquaculture governance are nominally governed by the same body, the ideological concerns of decision makers have not left space for the original users or ecological health. The right to good water quality and ecological health of artisanal fisher, original people and the broader coastal community are highlighted. Using semi structured interviews, participatory cartography and Geographic Information Systems fishers explain how the contamination footprint has expanded across benthic habitats. Diving in the contaminated areas confirmed the impacts using comparison with control sites. The article shows how new laws are need to assess nutrient loading, antibiotics and invasive species introduction. It links these impacts to literature in other countries where harmful algal blooms result from eutrophication from aquaculture contamination. It shows how the privatisation of space has left marine governance unable to take adequate enforcement. Artisanal and indigenous common properties can lead toward participation in marine planning for ecological health, whilst governmental institutions need realignment so that marine ecological planning for conservation can evolve.

The kinetically controlled synthesis of cephalexin in aqueous two-phase systems was studied, using immobilized penicillin acylase, 7-amino 3-desacetoxycephalosporanic acid as nucleophile and phenylglycine methyl ester as acyl donor. The organic phases used were 80% (v/v) polyethyleneglycol 400 and 600 and the aqueous phase was 2.5 M (NH 4 ) 2 SO 4 . 7-amino 3-desacetoxycephalosporanic acid and cephalexin partition coefficients were determined at pH 7.4 and 7.8, at 14 °C and 20 °C. Highest partition coefficient for cephalexin was obtained for polyethyleneglycol 400–(NH 4 ) 2 SO 4 at pH 7.4 and 20 °C, while the lowest partition coefficient for 7-amino desacetoxycephalosporanic acid was obtained in the same system at pH 7.8 and 14 °C. No significant effect of pH was observed on conversion yield and productivity of cephalexin synthesis; however, higher values were obtained with polyethyleneglycol 400 as organic phase. Higher conversion yields with both biphasic systems were obtained at the lowest temperature, where product hydrolysis was lower; volumetric productivity was higher for the fully aqueous medium (control), being higher at 20 °C. All parameters of synthesis were improved at higher substrates concentrations, obtaining conversion yields of 78.2% and 65.4%, with 60 mM 7-amino desacetoxycephalosporanic acid for the polyethyleneglycol 400–(NH 4 ) 2 SO 4 system and the control, respectively.

The presence of organic cosolvents was previously considered necessary to obtain high conversion yields in the synthesis of β-lactam antibiotics with immobilized penicillin acylase, and it is so when working at moderate substrate concentrations. Conversion yields close to stoichiometric and high productivities were recently reported for the synthesis of cephalexin at high substrate concentrations in ethylene glycol medium. Under such conditions, the effect of cosolvent concentration on yield is not significant so we raised the hypothesis that stoichiometric yields and high productivities are attainable at very high substrate concentrations in fully aqueous medium leading to substantial process improvement in terms of costs and environment. To test the hypothesis, the kinetically controlled synthesis of cephalexin with immobilized penicillin acylase was conducted in aqueous medium at substrates concentrations up to and beyond their solubilities at varying temperature, pH, enzyme to substrate and acyl donor to nucleophile ratios. At the best conditions, 99% conversion yield was attained with volumetric productivity of 300 mM/h and specific productivity of 7.8 mmol/h g cat . These values are slightly higher than those previously obtained under optimized conditions in organic medium so that the hypothesis has been confirmed, which opens up the possibility of efficiently produce the antibiotic through an environmentally friendly process.

The kinetically controlled synthesis of cephalexin in ethylene glycol was previously optimized at moderate substrate concentrations obtaining yields close to stoichiometric. A study is now presented on the production of cephalexin at very high substrates concentrations, up to 750 mM acyl donor, with immobilized and cross-linked enzyme aggregates (CLEA) of penicillin acylase. Since conversion yield close to 100% was already obtained, attention was given to productivity under the hypothesis that increasing substrates concentration will produce a substantial increase in productivity without reducing yield. An increase of 29 times in volumetric productivity and 4.5 times in specific productivity was obtained with PGA-450 with respect to the results obtained at moderate substrates concentrations (below 100 mM acyl donor). Volumetric productivity was lower for CLEA than for PGA-450, but specific productivity was almost the same for both. Sequential batch reactor operations were conducted to assess the biocatalyst operational stability and global productivity, considering one half-life as biocatalyst life cycle. Under such criterion, 40.1 and 135.5 g of cephalexin/g of biocatalyst were obtained for PGA-450 and CLEA, respectively. Yields remained close to 100% during the whole cycle. These are very good values which can be improved by optimizing the biocatalyst replacement criterion.

Organic cosolvents, and among them, polyols, are suitable media to perform the enzymatic synthesis of β-lactam antibiotics with immobilized penicillin acylase, because they effectively reduce water activity, depressing hydrolytic reactions in favor of synthesis. Among polyols, ethylene glycol has proven to be particularly suited as reaction medium for their synthesis. Previous studies have shown that pH, temperature, and cosolvent concentration are the most relevant variables in the kinetically controlled synthesis of cephalexin from 7-amino-3-deacetoxy cephalosporanic acid and phenylglycine methyl ester, conversion yield increasing at low temperatures and high cosolvent concentrations. The objective of this work is the optimization of temperature, pH, and ethylene glycol concentration in the kinetically controlled synthesis of cephalexin with immobilized penicillin acylase at lower than ambient temperature in terms of substrate molar conversion yield. Phenylglycine was used as acyl donor and 7-amino-3-deacetoxy cephalosporanic acid was the limiting substrate at 30 mM. Optimization was performed using surface of response methodology, optimum conditions being 12 °C, pH 6.8, and 60% (v/v) ethylene glycol, at which cephalexin yield was close to stoichiometric with respect to the limiting nucleophile, which is unattainable in aqueous medium. Stability of the biocatalyst at optimum conditions for cephalexin synthesis was very high, with a projected half-life of 1500 h, making it a suitable catalyst for the large-scale production of cephalexin.