Understanding the mechanical behaviour and properties of rocks is critical for industrial operations such as blasting, fracturing, drilling, crushing, and excavating. However, the effect of water and loading rates on the mechanical properties of rocks still remains to be understood. The effects of water content on the mechanical properties of rock under different loading rates were studied. The static and dynamic mechanical behaviour of dry and saturated Berea Sandstone were examined with a quasi-static loading machine and a split Hopkinson pressure bar (SHPB). Berea Sandstone is mainly composed of quartz (87%) with about 11% porosity. Overall, static compressive strength, Young's modulus, and tensile strength were significantly greater for dry samples than for saturated ones. In the dynamic tests, tensile strength was higher in the dry samples than in the water-saturated samples, whereas water did not have a significant effect on the dynamic compressive strength. Furthermore, compared to static loading conditions, the mechanical strength and Young's modulus under dynamic loading tests were significantly higher. Our results suggest that the effect of water on mechanical properties varies with the loading rate and testing method. This provides insight into how water content and loading rate affect rock mechanical properties and behaviour.

ABSTRACT This study was conducted to determine the total lysine requirement for female broiler breeders from days 14 to 42. Two-hundred and ten female broiler breeders were used in a completely randomized design with 6 replicates per treatment and 5 chicks per pen under restricted feeding. The contents of total lysine used in this experiment were 0.68, 0.72, 0.76, 0.80, 0.84, 0.88 and 0.92% in the diet. A basal diet was formulated to meet or to exceed the Ross 308 female broiler breeders’ nutrient specifications except for the lysine. Body weight and feed intake were measured to calculate feed efficiency, and body weight uniformity was defined on a weekly basis. One chick per pen was randomly selected to collect blood samples, organ and an abundance of sexual maturity associated miRNAs (miR-21, mi-26a and mi-375) in the plasma was measured on day 42. Increasing total lysine contents in the diet improved body weight gain and feed conversion ratio from days 14 to 42. The combined values from the two models for BW, average daily gain and feed efficiency were estimated at 1.04, 1.00 and 1.21% total lysine, respectively. Total lysine contents did not affect the ovary weight, serum estradiol-17b, serum progesterone and plasma urea nitrogen or the expression levels of the three miRNAs on day 42. Therefore, the results from the current study indicated that female broiler breeders fed on 0.68% total lysine could achieve the recommended BW, suggested by field practice when data were fitted into the overlapped point of linear-, and quadratic-plateau models.

RESUMO: O estudo foi realizado para examinar o efeito de duas auxinas sintéticas na embriogênese somática e na regeneração de plantas a partir de explantes de embriões maduros de 16 cultivares de cebola. Os cotilédones foram removidos a partir dos embriões e as porções restantes foram cultivadas em meio MS suplementado com 1,0 mg/L de 2,4-D e 5,0 mg/L de picloram sozinho ou em combinação (1,0 mg/L de 2,4-D + 2,5 mg/L de picloram) para produzir calos embriogênicos. Verificou-se que o meio MS suplementado com 5,0 mg/L de picloram foi o melhor tanto para a indução de calo embriogênico (85%) quanto para o diâmetro do calo (3,8 mm). Das 16 cultivares estudadas, Yeoeuijuhwang exibiu a menor freqüência de formação de calos embriogênicos (50,5%), ao passo que todas as outras 15 cultivares apresentaram mais de 60% de indução de calos embriogênicos. A análise dos calos por micrografia eletrônica de varredura (SEM) mostrou todas as fases dos embriões somáticos, tais como as fases globular, escutelar e coleoptilar. A regeneração de plantas foi significativamente afetada pela composição do meio de indução de calos embriogênicos. A maior frequência de conversão de embriões somáticos foi obtida a partir do calo embriogênico desenvolvido em meio MS com 2,4-D (70,1%) seguido por picloram (38,9%) e 2,4-D + picloram (34,5%). As plântulas germinadas foram desenvolvidas no meio contendo metade da dose de MS, com 3% de sacarose e foram aclimatizadas em ambiente de cultura com 98% de taxa de sobrevivência.

ABSTRACT: The study was undertaken to examine the effect of two synthetic auxins on somatic embryogenesis and plant regeneration from mature embryo explants of 16 onion cultivars. Cotyledons were removed from the embryos and remaining portions were cultured on MS medium supplemented with 1.0 mg/L 2,4-D and 5.0 mg/L picloram alone or in combination (1.0 mg/L 2,4-D + 2.5 mg/L picloram) to produce embryogenic callus. MS medium supplemented with 5.0 mg/L picloram was found to be the best one for both embryogenic callus induction (85%) and callus diameter (3.8 mm). Of the 16 cultivars studied, Yeoeuijuhwang exhibited the lowest frequency of embryogenic callus induction (50.5%), whereas all the other 15 cultivars showed more than 60% embryogenic callus induction. Scanning electron micrograph (SEM) analysis of embryogenic callus showed all stages of somatic embryos such as globular, scuetellar and coleoptilar. Plant regeneration was significantly affected by the composition of embryogenic callus induction medium. The greatest frequency of somatic embryo conversion was obtained from embryogenic callus developed in MS medium with 2,4-D (70.1%) followed by picloram (38.9%) and 2,4-D + picloram (34.5%). The germinated plantlets were further developed on the half-strength MS medium containing 3% sucrose and were acclimatized in the culture room with 98% survival rate.