Second-harmonic generation of ZnO nanoparticles synthesized by laser ablation of solids in liquids

We report the synthesis of small zinc oxide nanoparticles (ZnO NPs) based colloidal suspensions and the study of second-harmonic generation from aggregated ZnO NPs deposited on glass substrates. The colloidal suspensions were obtained using the laser ablation of solids in liquids technique, ablating a Zn solid target immersed in acetone as the liquid medium, with ns-laser pulses (1064 nm) of a Nd-YAG laser. The per pulse laser fluence, the laser repetition rate frequency and the ablation time were kept constant. The absorption evolution of the obtained suspensions was optically characterized through absorption spectroscopy until stabilization. Raman spectroscopy, SEM and HRTEM were used to provide evidence of the ZnO NPs structure. HRTEM results showed that 5–8 nm spheroids ZnO NPs were obtained. Strong second-harmonic signal is obtained from random ZnO monocrystalline NPs and from aggregated ZnO NPs, suggesting that the high efficiency of the nonlinear process may not depend on the NPs size or aggregation state

Microbial biocatalytic preparation of 2-furoic acid by oxidation of 2-furfuryl alcohol and 2-furanaldehyde with Nocardia corallina

The preparation of 2-furoic acid via oxidation of 2-furfuryl alcohol and 2-furanaldehyde was studied by two procedures using whole cells of Nocardia corallina B-276. We describe a comparison using a batchcultivation (3-L) versus resting cells in potassium phosphate buffer (0.1 M, pH 7.0). In the 3-L bioreactor, 2-furfuryl alcohol (1.35 g/L) was biotransformed after 24 h, to the acid with 81% yield. The bioconversionof 2-furfuryl alcohol using resting cells leads to and almost quantitative yield (98%) of 2-furoic acid in 21 h. 2-furanaldehyde was also oxidized to the 2-furoic acid in 88% yield in 8 h, the ratio substrate:cellswas 1:3.5 (w/w). This method was scaled up to 9 g/L of 2-furanaldehyde

Respiratory viruses: their importance and lessons learned from COVID-19

Respiratory virus infection can cause severe illnesses capable of inducing acute respiratory failure that can progress rapidly to acute respiratory distress syndrome (ARDS). ARDS is related to poor outcomes, especially in individuals with a higher risk of infection, such as the elderly and those with comorbidities, i.e. obesity, asthma, diabetes mellitus and chronic respiratory or cardiovascular disease. Despite this, effective antiviral treatments available for severe viral lung infections are scarce. The coronavirus disease 2019 (COVID-19) pandemic demonstrated that there is also a need to understand the role of airborne transmission of respiratory viruses. Robust evidence supporting this exists, but better comprehension could help implement adequate measures to mitigate respiratory viral infections. In severe viral lung infections, early diagnosis, risk stratification and prognosis are essential in managing patients. Biomarkers can provide reliable, timely and accessible information possibly helpful for clinicians in managing severe lung viral infections. Although respiratory viruses highly impact global health, more research is needed to improve care and prognosis of severe lung viral infections. In this review, we discuss the epidemiology, diagnosis, clinical characteristics, management and prognosis of patients with severe infections due to respiratory viruses

Voltage feed-forward performance in stationary reference frame controllers for wind power applications

In order to improve the connected current and the response speed of the controller, stationary reference frame control strategy with proportional resonant (P-R) controller due to its high dynamic and good harmonic compensation performance characteristics was already used in many different DG applications. This paper introduced an additional stationary reference frame control strategies with voltage feed-forward method. By using this method, both the quality of grid connected current and the dynamic performance are improved, which also validated by experiments.Postprint (published version

Dermanyssus gallinae in layer farms in Kosovo: a high risk for salmonella prevalence

Background The poultry red mite (PRM), Dermanyssus gallinae (D.g.) is a serious ectoparasitic pest of poultry and potential pathogen vector. The prevalence of D. g. and the prevalence of Salmonella spp. within mites on infested laying poultry farms were investigated in Kosovo. Findings In total, 14 populated layer farms located in the Southern Kosovo were assessed for D. g. presence. Another two farms in this region were investigated 6 months after depopulation. Investigated flocks were all maintained in cages, a common housing system in Kosovo. A total of eight farms were found to be infested with D. g. (50%) at varying levels, including the two depopulated farms. The detection of Salmonella spp. from D. g. was carried out using PCR. Out of the eight layer farms infested with D. g., Salmonella spp. was present in mites on three farms (37.5%). Conclusions This study confirms the high prevalence of D. g. in layer flocks in Kosovo and demonstrates the link between this mite and the presence of Salmonella spp. on infested farms

Effect of inulin and probiotic bacteria on growth, survival, immune response, and prevalence of white spot syndrome virus (WSSV) in Litopenaeus vannamei cultured under laboratory conditions

The effect of inulin and probiotic bacteria on the growth, survival, immune response and viral prevalence of white spot syndrome virus (WSSV) in white shrimp was evaluated. Presumptive bacilli and lactic acid bacteria (LAB) were characterized for hemolytic and enzymatic activity, hydrophobicity and antagonism against Vibrio. Selected isolates (Bacilli and LAB) were included in the diet of juvenile shrimp. Two bioassays were conducted with treatments by triplicate (10 shrimp per replicate) with inulin and inulin and bacteria. Fourteen LAB and six bacilli isolates had potential as probiotics. Survival and growth was not affected by the addition of the inulin and bacteria to diet. Inulin and bacteria improved immunity in cultured shrimp. Also, these feed additives reduced the prevalence of WSSV in cultured shrimp.Keywords: Probiotics, prebiotics, white spot syndrome virus (WSSV), immune system, Litopenaeus vannameiAfrican Journal of Biotechnology Vol. 12(21), pp. 3366-337

Las competencias en ambientes virtuales: instrumentos y evaluación

Ante la cada vez más creciente adopción de los modelos educativos no convencionales por parte de las instituciones educativas de nivel superior, es necesario conocer el nivel en el desarrollo de las competencias que en estas modalidades el estudiante llega a tener.En los programas educativos ofertados en modalidades a distancia, se puede suponer que el estudiante tiene una ventaja al realizar las evaluaciones que no tendría de tener que realizar una evaluación presencial. Esto es, al estar físicamente lejos del docente el estudiante puede valerse de diversos recursos a los que puede consultar mientras realiza una evaluación, dejando así la incógnita de qué tanto realmente el estudiante adquiere las competencias que se supone debe evidenciar al término de cualquier curso.El enfoque por competencias profesionales adoptado recientemente por la mayoría de las universidades latinoamericanas, conjunta competencias genéricas comunes a todas las carreras afines a ciertas áreas del conocimiento, así como competencias específicas a cada disciplina. Una adecuada selección de los métodos e instrumentos de evaluación puede certificar la adecuada adquisición de las competencias.Realizar esta medición no es tarea sencilla. Los métodos e instrumentos utilizados para evaluar en ambientes virtuales se actualizan e innovan constantemente a fin de afinar esta cuestión.En este artículo se realiza una investigación sobre algunos de los métodos e instrumentos de evaluación que actualmente se utilizan en estas modalidades