Ni-Ru supported on CeO2 obtained by mechanochemical milling for catalytic hydrogen production from ammonia.

Developing active and stable catalysts for carbon-free hydrogen production is crucial to mitigate the effects of climate change. Ammonia is a promising carbon-free hydrogen source, as it has a high hydrogen content and is liquid at low pressure, which allows its easy storage and transportation. We have recently developed a nickel-based catalyst with a small content of ruthenium supported on cerium oxide, which exhibits high activity and stability in ammonia decomposition. Here, we investigate mechanochemical milling for its synthesis, a faster and less energy-consuming technique than conventional ones. Results indicate that mechanochemical synthesis increases catalytic activity compared to the conventional incipient wetness impregnation method. The interaction between the metal precursors and the support is key in fine-tuning catalytic activity, which increases linearly with oxygen vacancies in the support. Moreover, the mechanochemical method modifies the oxidation state of Ni and Ru species, with a variation depending on the precursors.

Vasculitis del sistema nervioso central

La vasculitis primaria del Sistema Nervioso Central (VPSNC) se refiere a un grupo de enfermedades que resultan de la inflamación y destrucción de los vasos sanguíneos de la médula espinal, encéfalo y meninges, tanto en el sector venoso como arterial, esto puede conducir a la oclusión o formación de aneurismas, con las consiguientes alteraciones isquémico-hemorrágicas.1 La presentación es heterogénea y poco sistematizable. El diagnóstico se establece con un cuadro clínico compatible, una angiografía o biopsia del parénquima encefálico y/o meninges que evidencien vasculitis. Presentamos el caso de un paciente portador de retrovirus con probable VPSNC con clínica compatible, hallazgos imagenológicos sugestivos, con escasa alteración de LCR y EEG.2

Primary vasculitis of the Central Nervous System (VPSNC) refers to a group of diseases that result from inflammation and destruction of the blood vessels of the spinal cord, brain and meninges, both in the venous and arterial sector, this can lead to the occlusion or formation of aneurysms, with the consequent ischemic-hemorrhagic alterations.1 The presentation is heterogeneous and little systematizable. The diagnosis is established with a compatible clinical picture, an angiography or biopsy of the brain parenchyma and/or meninges that show vasculitis. We present the case of a patient with a retrovirus with probable NCPSV with compatible symptoms, suggestive imaging findings, with little CSF and EEG alteration.2

Primer Consenso Nacional Intersociedades de Inmunización del Adulto. 2023

Las vacunas previenen millones de muertes cada año y su eficacia y seguridad han sido ampliamente establecidas. En términos económicos, la vacunación es una de las intervenciones sanitarias más costo efectivas, generando un importante ahorro y crecimiento económico que supone a largo plazo. Se ha demostrado que la vacunación de adultos disminuye la morbilidad y la mortalidad asociadas a enfermedades infecciosas prevenibles, reduciendo las complicaciones y las hospitalizaciones, incluidos los ingresos a las unidades de cuidados intensivos. Hemos elaborado este documento de consenso con el objeto de diseñar un esquema de vacunación pragmático, accesible y estandarizado del adulto, según categoría de riesgo y edad, sobre la base de la evidencia disponible de vacunas accesibles y nuevas vacunas habiendo utilizado el Tercer Consenso de la Sociedad Paraguaya de Infectología del 2019 como base para las recomendaciones finales.

SUMMARY Vaccines prevent millions of deaths each year, and their efficacy and safety have been widely established. In economic terms, vaccination is one of the most cost-effective health interventions, generating significant savings and long-term economic growth. Adult vaccination has been shown to decrease morbidity and mortality associated with preventable Infectious diseases, reducing complications and hospitalizations, including admissions to intensive care units. We have prepared this consensus document in order to design a pragmatic, accessible and standardized vaccination scheme for adults, according to risk category and age, based on the available evidence of available vaccines and new vaccines, having used the third consensus of the Paraguayan Infectious Diseases Society of 2019 as a basis for the final recommendations.

Infection parameters of Heterorhabditis amazonensis (Nematoda: Heterorhabditidae) in different stages of Hibiscus pink mealybug.

The pink hibiscus mealybug Maconellicoccus hirsutus (Hemiptera: Pseudococcidae) is an invasive pest of an enormous variety of crops and has become a concern in many parts of the world. Early attempts to control M. hirsutus with chemical insecticides and cultural methods have failed due to the cryptic habit of the insect. We assessed the entomopathogenic nematode Heterorhabditis amazonensis as a biological agent against different insect stages. Comparing different concentrations of the nematode, insect females were very susceptible, with more than 90% of the insects killed. In second and third nymphal stages mortality rates varied from 20 to 60% depending on the nematode concentration. The first nymphal stage as much less susceptible to nematodes due to their small size. The number of nematodes capable of invading the insect host did not vary between the different concentrations. However, the LC50 for females (35.2 IJ/insect), second and third nymphal stages (83.9 IJ/insect) demonstrated that H. amazonensis should be considered as a potential biocontrol agent of the pink hibiscus mealybug.The pink hibiscus mealybug Maconellicoccus hirsutus (Hemiptera: Pseudococcidae) is an invasive pest of an enormous variety of crops and has become a concern in many parts of the world. Early attempts to control M. hirsutus with chemical insecticides and cultural methods have failed due to the cryptic habit of the insect. We assessed the entomopathogenic nematode Heterorhabditis amazonensis as a biological agent against different insect stages. Comparing different concentrations of the nematode, insect females were very susceptible, with more than 90% of the insects killed. In second and third nymphal stages mortality rates varied from 20 to 60% depending on the nematode concentration. The first nymphal stage as much less susceptible to nematodes due to their small size. The number of nematodes capable of invading the insect host did not vary between the different concentrations. However, the LC50 for females (35.2 IJ/insect), second and third nymphal stages (83.9 IJ/insect) demonstrated that H. amazonensis should be considered as a potential biocontrol agent of the pink hibiscus mealybug.

Steinernema goweni n. sp. (Rhabditida: Steinernematidae), a new entomopathogenic nematode from Zulia State, Venezuela.

A nematode from the genus Steinernema was isolated in Zulia state (North-western, Venezuela). Morphological, morphometric and molecular studies indicated that this nematode belongs to the "bicornutum" group and is described herein as Steinernema goweni n. sp. Steinernema goweni n. sp. is characterised by morphometrics of its infective juveniles, with body length 640 (531-719) µm, pharynx length of 119 (109-126) µm, tail of 67 (59-89) µm, c ratio = 9 (6-11) and E% = 77 (48-94). First generation male specimens can be recognised by the shape and size of spicules (55 (50-57) µm long) and gubernaculum (35 (30-40) µm long), and %D value 42 (28-59), which is at the lower limit within the "bicornutum" group. The number of genital papillae in males is also distinctive for S. goweni n. sp. presenting up to 27 (13 pairs + 1) papillae in 15% of specimens. The phasmids can be seen in scanning electron microscopy in all stages, characters not previously reported within the "bicornutum" group. Phylogenetic analyses of the "bicornutum" group based on both ITS and D2D3 regions showed a clear separation of S. goweni n. sp. from the other species. In both analyses S. goweni n. sp. formed a strongly supported group of American species.

Size does matter: the life cycle of Steinernema spp. in micro-insect hosts.

The life cycle of four Steinernema species was observed in 4 insect micro-insect host species (less than 5mm long). Several parameters were measured: sex ratio of invading nematodes, percentages of host infection and offspring production, penetration rate of infective juveniles per insect and number of new generation of infective juveniles. All parameters varied among nematode species, micro-host species and application rates. All Steinernema species were capable to invade micro-insect hosts, however, invasion decreased as insect size decreased and as nematode species size increased. None of the nematode species achieved 100% mortality in the micro-hosts. Due to size differences in the nematode species, Steinernema glaseri was less capable of completing its life cycle and unable to invade smaller hosts whereas S. riobrave completed its life cycle in smaller hosts more frequently. The number of invading nematodes and the number of offspring produced had the same levels regardless of the nematode application rates, those results showed a maximum top in the number of individuals per micro-insect host. The offspring production in thrips species was only possible by endotokia matricida in S. riobrave. The sex of the invader nematodes also impeded the life cycle of S. affine because males colonized the entire body of the micro-insect host leaving no room for female invasion. The size of the host plays an irrefutable role in limiting the development of nematodes and it appears improbable that an entomopathogenic nematode population can persist in the soil without the presence of bigger insects.

Ammonia concentration at emergence and its effects on the recovery of different species of entomopathogenic nematodes.

The life cycle of entomopathogenic nematodes (EPN) occurs inside an insect cadaver and an accumulation of ammonia initiates as a consequence of the nematodes defecation. This accumulation reduces the food resources quality and creates a detrimental environment for nematodes. When a given ammonia concentration is reached, the nematodes start their emergence process, searching for a new host. In the present work, this parameter, ammonia triggering point (ATP) was measured in 7 Steinernema species/strains. The effect of different ammonia concentrations on the recovery process and their consequences in the nematodes survival were also investigated. The results indicate that ATP varies among nematode species; Steinernema glaseri showed the highest ATP of the evaluated species (1.98±2.6 mg of NH4-N*g of Galleria mellonella(-1)); whereas Steinernema riobrave presented the lowest ATP (1.16±0.1 mg of NH4-N*g of G. mellonella(-1)). On the other hand, the nematode emergence could be a repulsive response when ATP is reached. As the ammonia concentration increased the recovery percentage of Steinernema feltiae (Chile strain) dropped gradually from 79.4±11.9% in the control treatment to 0% when 1mg of NH4-N*ml of bacterial broth(-1) was added. It is possible, that emergence process could be a repulsive response of the nematodes due to ammonia concentration when is reaching the ATP. The role of ammonia inside the insect cadavers, might suggests connections with some stages of the EPN life cycle.

Characterization of Xenorhabdus and Photorhabdus bacteria by Fourier transform mid-infrared spectroscopy with attenuated total reflection (FT-IR/ATR).

The use of Fourier transform mid-infrared spectroscopy with attenuated total reflection for characterizing entomopathogenic bacteria from genera Xenorhabdus and Photorhabdus is evaluated for the first time. The resulting spectra of Xenorhabdus poinarii and Photorhabdus luminiscens were compared with the spectrum of Escherichia coli samples. The absorption spectra generated by the bacteria samples, were very different at the region below 1400cm(-1) which represents the stretching vibrations of phosphate and carbohydrates. Star diagrams of the fingerprint section of nematodes spectra (between 1,350 and 1,650 cm(-1)) for separation between spectra was used and showed to be a useful tool for classification purposes.