Effect of Nb on Microstructure and Mechanical Property of Novel Powder Metallurgy Superalloys during Long-Term Thermal Exposure

Microstructure and mechanical properties of novel Ni-20Co-12Cr superalloys, with and without Nb addition, were systematically studied during long-term thermal exposure. With increased exposure time, the average diameter of the γ′ precipitates increased in both alloys in succession; this is more obviously observed in alloy containing 1 wt% Nb (1Nb). It is suggested that Nb increased the γ′ coarsening rate by accelerating the diffusion of Al and Nb in γ matrix. In addition, the γ′ phase fraction is increased by about 4% in 1Nb compared to the alloy without Nb (0Nb). The morphology of the γ′ phase changed from near-spherical to cuboidal shape during exposure in both alloys. Due to the increased γ/γ′ lattice misfit by Nb addition, 1Nb alloy showed an earlier tendency of shape change. Vickers hardness results revealed that the overall hardness decreased with the exposure time because the size increment of the γ′ precipitate weakened the precipitates strengthening and Orowan strengthening.

Baseline growth of the Trinidad freshwater crab Poppiana dentata () under laboratory conditions

Poppiana dentata (Randall, 1840) is widely distributed throughout riverine habitats in Trinidad. However, there is a scarcity of information on the biology of this species. This study provides the first baseline examination that describes growth aspects for P. dentata. Juvenile crabs were obtained from berried females collected in northwest Trinidad. Carapace width (CW), length (CL), moult incident, intermoult period and qualitative aspects were recorded for crabs (N = 23) over 9 months. CW, CL and intermoult period were used to derive percentage size increment, specific growth rate (SGR) and size at structural maturity for both sexes. Growth curves and logistic equations were also generated for each sex. Hatched crabs (< 5 mm CW) underwent rapid hardening after their first moult, indicating a fast turnover of moult cycles. SGR and CW percent increment were also the highest for this initial moult (P < 0.05). CW, CL, intermoult period, size increment and SGR did not differ between sexes (P > 0.05), with logistic equations expressed as CW = 32.81 (1+exp (1.481 ̵ 0.031t))-1 for males and CW = 34.07 (1+exp (1.516 ̵ 0.027t))-1 for females. Yet, breakpoint analyses indicated dissimilar sizes for structural maturity (male: 28.40 mm CW; female: 16.84 mm CW). These patterns reflect a shorter life span for this species in comparison to what has been reported for other trichodactylid relatives. This can have implications for P. dentata populations residing in anthropogenically disturbed habitats; thus, highlighting the need for conservation strategies to ensure preservation of native wild stock.

PENGARUH PUPUK MAJEMUK TABLET TERHADAP PERTUMBUHAN LILIT BATANG DAN HARA DAUN TANAMAN KARET

AbstrakHarga karet alam dunia yang volatil saat ini telah menyebabkan munculnya inovasi dalam pemupukan tanaman karet diantaranya penggunaan pupuk majemuk tablet. Percobaan pemupukan telah dilakukan pada TBM karet umur 3 tahun yang bertujuan untuk mengetahui pengaruh pupuk majemuk tablet terhadap pertumbuhan lilit batang dan kandungan hara daun. Terdapat tiga perlakuan dalam penelitian ini yaitu, (A) pupuk majemuk briket (500 g/pohon/tahun) sebagai kontrol, (B) pupuk majemuk tablet (200 g/pohon/tahun) atau setara dengan 40% kontrol, dan (C) pupuk majemuk tablet (300 g/pohon/tahun) atau setara dengan 60% kontrol. Formulasi pupuk majemuk yang digunakan adalah 18–1014–2+1TE. Hasil penelitian menunjukkan bahwa penyerapan hara N dan K pada perlakuan A lebih cepat yang direfleksikan melalui hara daun A yang lebih tinggi dibandingkan B dan C. Walaupun hara daun N dan K pada perlakuan A relatif lebih tinggi, tetapi penambahan lilit batang terbesar terdapat pada perlakuan C kemudian A dan B, yaitu 7,52 cm; 7,23 cm; dan 6,99 cm (P = 0,23). Tidak ditemukan korelasi yang kuat antara penambahan ukuran lilit batang dengan kandungan hara daun (P = 0,66) tetapi terdapat korelasi positif yang cukup kuat (r = 0,64; P = 0,025) antara penambahan ukuran lilit batang dengan curah hujan.Abstract The world’s natural rubber price that is volatile has led to the innovation in rubber trees fertilization by using tablet fertilizer. The study of fertilization was conducted in an immature rubber tree 3 years planted (TBM 3) to find out the responses of fertilization in rubber girth and leaf nutrient content. Three treatments were established viz. (A) briquette fertilizer 500 g/tree/year as control, (B) tablet fertilizer 200 g/tree/year equivalent to 40% of control, (C) tablet fertilizer 300 g/tree/year equivalent to 60% of control. The formula of briquette and tablet was identic (18–10–14–2+1TE). The results show that nitrogen and potassium uptake in treatment briquette fertilizer 500 g/tree/year (A) was faster, it was reflected through leaf nutrient content that was higher than B and C. Even though the contents of N and K in rubber leaf in A was relatively higher however the highest girth increment occurred in C then A and B, i.e. 7.52 cm; 7.23 cm; and 6.99 cm respectively. No strong correlation between girth size increment and nutrient leaf status in this study (P = 0.66). However a moderately strong correlation (r = 0.64; P = 0.025) appeared between girth size increment and monthly precipitation.

Data size increment for fault detection on rotating machinery

En los últimos años se ha incrementado el uso de técnicas de modelamiento basado en datos para el diagnóstico de fallos en maquinaria rotativa. Estas técnicas requieren de grandes cantidades de datos que no siempre se pueden obtener pues generan altos costos y tiempo excesivo, que son difíciles de solventar desde el punto de vista económico y técnico. El presente trabajo se enfoca en el pre-procesamiento de las señales de vibración y propone un método para incrementar el número de series temporales informativas de una máquina rotativa sin el incremento del tiempo y costos en la etapa de adquisición de las señales. Como resultado se ha obtenido una ampliación de 315 señales en la fase de adquisición de datos a 429000 luego de la aplicación del método; cantidad adecuada para la construcción de modelos basados en datos, incluso de deep learning para la detección de fallos en maquinaria rotativa. Palabras clave: Adquisición de datos, pre-procesamiento, rodamientos, señales.

Correlation between photoelectrochemical and photoluminescence measurements of Ag-doped ZnO/ITO photoanode

Silver-doped zinc oxide (SZO) thin films have been deposited onto indium-doped tin oxide substrates (ITO) using sol–gel spin-coating technique with different Ag doping content (1, 2 and 5% Ag). The effect of silver incorporation on structural, morphological, optical and photoelectrochemical (PEC) properties of the SZO films was investigated. Ag incorporation resulted in an enhanced grain size and thickness of elaborated SZO films. Scanning electron micrographs exhibited a uniform distribution of spherical grains with particle size increment after doping. Band gap energies were found to increase after Ag doping. Photoluminescence (PL) measurements revealed that the energy band gaps of the films were in the UV region. As compared to pure ZnO thin film, the samples are more photoactive, and the film containing 2% Ag yielded the highest photocurrent. A correlation study between PEC and PL measurements of Ag-doped ZnO/ITO photoanode leads to a reverse variation. Charge transfer processes at the ZnO–electrolyte interface were identified by electrochemical impedance spectroscopy.

New trepostomate bryozoans from the Upper Ordovician of Morocco and the temperature influence on zooid size

New Upper Ordovician trepostomate bryozoans from the eastern Anti-Atlas of Morocco have been identified. They have been collected from the lower and intermediate units of the Khabt-el-Hajar Formation, late Katian in age, representing, respectively, bryozoan-pelmatozoan meadows with siliciclastic input, degraded by wave activity in a mid-ramp setting, and outer-ramp environments with marly substrates. Ten species of the generaCyphotrypa,Calloporella,Diplotrypa,Parvohallopora,Dekayia, andAostiporaare described. Of them, three species are new:Cyphotrypa regularisJiménez-Sánchez,Parvohallopora cystataJiménez-Sánchez, andAostipora elongataJiménez-Sánchez. Univariate statistical analyses of the sub-polar Moroccan species, in addition to other congeneric species of high, middle, and low latitudes, corroborate that for the trepostomate bryozoan the temperature of the ambient water was a primary control on zooecium size variations. Nevertheless, other environmental factors, besides temperature, must have also influenced significantly the zooid size, at least in low latitudes. Our data also give further support for considering the zooecium wall thickness as a limiting factor for the zooid size increment with latitude in the trepostomates.

Effect of temperature on the survival and growth of freshwater prawns Macrobrachium borellii and Palaemonetes argentinus (Crustacea, Palaemonidae)

During the two-month rearing period, the effect of four water temperatures (15°C, 20°C, 25°C and 30°C) on survival rate, number of molts, and growth rate (molt increment and intermolt period) of juvenile Macrobrachium borellii Nobili, 1896 and Palaemonetes argentinus Nobili, 1901 prawns was evaluated in laboratory conditions. The two species showed some similarities in their both survival and growth pattern at different temperatures. The survival rate was highest at 20°C and 25°C, decreasing at the lowest temperature. The number of molts increased at higher temperatures, ranging the intermolt period from 22.2 days to 9.9 days, for M. borellii, and from 20.8 to 9.5 days for P. argentinus, corresponding those values to 15°C and 30°C, respectively. No difference between species was noted in the intermolt period. The size increment by molting increased significantly from 15°C to 25°C, whereas a reduction in the growth of prawns was observed at 30°C. Significant differences among temperatures were found in the slope of regressions between the size increment by molting and the cephalothorax length. M. borellii showed a significantly higher tolerance to elevated temperature and a faster growth (about twice at 25°C) than P. argentinus. These differences could provide M. borellii a competitive advantage for a better adaptation to the dynamic of freshwater environment, especially in areas with anthropogenic impact.