Reactive compatibilization of PC/PVDF polymer blends by zinc carboxylate containing poly(methylmethacrylate)ionomers

Polycarbonate (PC) has been reacted with a random copolymer of methylmethacrylate and 6 mol% of acrylic acid (poly(MMA-co-AA)) and with this copolymer neutralized (totally or not) by Zn cations. When conducted in solution at 240°C, the reaction leads to the grafting of PC onto the copolymer neutralized or not. In the melt at 235°C, the grafting reaction occurs only when the copolymer is at least partly neutralized. Whatever the experimental conditions (solution or bulk), PMMA does not react with PC, which confirms that the acidolysis of PC is at the origin of the grafting reaction. Poly(vinylidene fluoride) (PVDF) and PC have been melt blended at 235°C in the presence of the poly(MMA-co-AA) copolymer totally neutralized or not by Zn cations, the purpose being the reactive formation of PMMA-g-PC copolymer that would act as compatibilizer for the PC/PVDF blend. The phase morphology and the mechanical properties of the compatibilized PC/PVDF blends have been compared with the parent non-reactive polyblends. Compared to the modification of PVDF by 20 wt% of PMMA, the use of 20 wt% of the partly neutralized poly(MMA-co-AA) copolymer decreases further the average size of the dispersed phase, enhances its adhesion to the matrix, and results in a considerable increase of the elongation at break. The beneficial effect of zinc carboxylate in the PMMA copolymer is explained by the grafting of PC onto PMMA at the interface

Determination of carbendazim residues in Moroccan tomato samples using local enzyme-linked immunosorbent assay and comparison with liquid chromatography

The fungicide carbendazim (CBZ) is not approved for agricultural uses in some countries but is still used by many farmers due to its effectiveness. For this reason, in previous work of the same authors, they developed a competitive enzyme immunoassay (ELISA) using rabbit polyclonal antibodies to detect CBZ. This study aimed to validate this in-house ELISA after extraction with methanol for CBZ analysis in tomato samples, and the results were compared with the conventional high-performance liquid chromatography (HPLC) method after QuEChERS extraction. The results showed that both ELISA and HPLC methods have good repeatability, reproducibility and high precision with a good variation verified by principal components analysis (PCA). ANOVA tested the detection limit (LOD), and quantification limit (LOQ), and the values for ELISA (LOD = 0.026± 0.001 µg/L and LOQ = 0.083 ± 0.003 µg/L) were significantly lower than those obtained by HPLC (LOD = 0.61 ± 0.02 µg/L and LOQ = 1.85 ± 0.07 µg/L). ELISA and HPLC were used for analyzing CBZ in 100 Moroccan tomato samples. These two methods detected the presence of CBZ above the Maximum Residue Limit (MRL) level in 9 samples. However, the presence of the  CBZ was detected in the 79 samples by ELISA and quantified in 66 samples. In contrast, the presence of CBZ was detected in 57 and quantified in 35 samples by HPLC. These results showed that the ELISA system coupled with a simple methanol extraction is much more sensitive than HPLC after QuEChERS extraction

Backstepping nonlinear control to maximize energy capture in a variable speed wind turbine

We are considering the problem of maximum power point tracking MPPT in wind energy conversion system (WECS). The paper proposes a new control strategy to maximize the wind aerodynamic energy captured in variable speed wind turbine with a separately excited DC-Generator and transformed to the battery through a controlled DC-DC converter. The proposed strategy controls the stip speed ratio via the rotor angular speed to an optimum point at wich the power coefficient is maximal. The controller is designed using the backstepping technique. A formal analysis based on lyapunov stability is developed to describe the control system performances. In addition to closed-loop global asymptotic stability, it is proved that the controller actually meets the MPPT requirement. The above results are confirmed by simulations.

Potential effect of fruit and flower extracts of Arbutus unedo L. on Tetrahymena pyriformis exposed to a cobalt-60 source

Exposure of Tetrahymena pyriformis cultures to cobalt-60 for 72 h significantly impacted the cells' growth, appearance, and physiology. This study aims to investigate the protective effects of Arbutus unedo L flowers and fruit extracts on T. pyriformis against gamma radiation. Initially, aqueous and 50% ethanolic extracts of the fruits and flowers were prepared, and their cytotoxicity on the ciliate was evaluated. The irradiated ciliate's cellular viability and morphological aspect improved when a non-toxic concentration of 25 µg/mL was added to the growth medium. The addition of extracts restored glyceraldehyde-3-phosphate dehydrogenase and succinate dehydrogenase activities to their initial levels, similar to non-irradiated cells. In addition, the extracts reduced oxidative stress markers, such as lipid peroxidation, and decreased the activities of antioxidant defence enzymes, catalase, and superoxide dismutase. This may be attributed to the antioxidant properties of the extracts. Results of this study revealed that the flower extracts exhibited better protective effects than the fruit extracts, with superior antioxidant activity in the in-vitro DPPH scavenging assay. These results suggest that A. unedo flower extracts may have potential as exogenous radioprotective agents

N′-(1-Allyl-2-oxoindolin-3-yl­idene)benzohydrazide

In the title compound, C18H15N3O2, the dihedral angle between the ring systems is 15.1 (1)°. The amino H atom is hydrogen bonded to the exocyclic O atom of the five-membered ring, forming an S(6) motif

1-Benzyl-3-methyl­quinoxalin-2(1H)-one

The asymmetric unit of the title compound, C16H14N2O, contains three independent mol­ecules. The dihedral angles between the quinoxaline and phenyl planes in the three mol­ecules are 82.58 (8), 85.66 (9) and 85.36 (9)°. The crystal packing is stabilized by C—H⋯O and C—H⋯N hydrogen bonds

N′-(3-Methyl­quinoxalin-2-yl)-N′-phenyl­benzohydrazide

In the crystal structure of the title compound, C22H18N4O, the quinoxaline system makes dihedral angles of 86.59 (7) and 63.37 (9)° with the benzohydrazide and phenyl rings, respectively. The benzohydrazide ring makes a dihedral angle of 72.46 (10)° with the phenyl ring. The crystal structure is stabilized by inter­molecular N—H⋯O hydrogen bonds, C—H⋯O contacts and C—H⋯π inter­actions

A Homolog of FHM2 Is Involved in Modulation of Excitatory Neurotransmission by Serotonin in C. elegans

The C. elegans eat-6 gene encodes a Na+, K+-ATPase α subunit and is a homolog of the familial hemiplegic migraine candidate gene FHM2. Migraine is the most common neurological disorder linked to serotonergic dysfunction. We sought to study the pathophysiological mechanisms of migraine and their relation to serotonin (5-HT) signaling using C. elegans as a genetic model. In C. elegans, exogenous 5-HT inhibits paralysis induced by the acetylcholinesterase inhibitor aldicarb. We found that the eat-6(ad467) mutation or RNAi of eat-6 increases aldicarb sensitivity and causes complete resistance to 5-HT treatment, indicating that EAT-6 is a component of the pathway that couples 5-HT signaling and ACh neurotransmission. While a postsynaptic role of EAT-6 at the bodywall NMJs has been well established, we found that EAT-6 may in addition regulate presynaptic ACh neurotransmission. We show that eat-6 is expressed in ventral cord ACh motor neurons, and that cell-specific RNAi of eat-6 in the ACh neurons leads to hypersensitivity to aldicarb. Electron microscopy showed an increased number of synaptic vesicles in the ACh neurons in the eat-6(ad467) mutant. Genetic analyses suggest that EAT-6 interacts with EGL-30 Gαq, EGL-8 phospholipase C and SLO-1 BK channel signaling to modulate ACh neurotransmission and that either reduced or excessive EAT-6 function may lead to increased ACh neurotransmission. Study of the interaction between eat-6 and 5-HT receptors revealed both stimulatory and inhibitory 5-HT inputs to the NMJs. We show that the inhibitory and stimulatory 5-HT signals arise from distinct 5-HT neurons. The role of eat-6 in modulation of excitatory neurotransmission by 5-HT may provide a genetic explanation for the therapeutic effects of the drugs targeting 5-HT receptors in the treatment of migraine patients

Tuberculose et insuffisance rénale

La survenue de la tuberculose chez l’insuffisante rénale chronique n’est pas rare, elle peut poser un problème de diagnostic et de prise en charge thérapeutique. Notre objectif est d’établir les caractéristiques cliniques, thérapeutiques et évolutives de la tuberculose chez les insuffisants rénaux chroniques. Il s’agit d’une étude rétrospective sur 5 ans portant sur 23 patients insuffisants rénaux au stade d’hémodialyse présentant une tuberculose. Le bilan de la tuberculose a comporté un interrogatoire, un examen clinique, une radiographie thoracique, une intradermoréaction à la tuberculine et la recherche de bacilles de Koch (BK) dans les liquides biologiques ou dans les tissus biopsiés.  La tuberculose est retrouvée 16 femmes et 7 hommes, elle est survenue en moyenne dans les 3 premières années de début de dialyse. Les signes d’appel sont peu spécifiques et l’anergie tuberculinique est notée chez 6 patients,  L’atteinte tuberculeuse était parenchymateuse dans 10 cas dont 2 cas de miliaire, pleurale dans 7 cas, ganglionnaire dans 3 cas et 3 cas sont traités comme tuberculose pulmonaire à microscopie négative. Nos patients ont reçu le régime RHZ avec ou sans l’éthambutol selon l’indication. Le pyrazinamide est administré après la séance d’hémodialyse. Huit pour cent de nos patients sont décédés alors que l’évolution était favorable chez le reste