National Academy Science Letters最新文献

Contamination of agroecosystems by metallic ions on various scales significantly reduces crop productivity and yield due to their toxic effects on beneficial soil microbiota. This study investigates the toxic effects of heavy metals chromium (Cr), lead (Pb), nickel (Ni) and metallic nanoparticles silver (AgNPs) and zinc oxide (ZnONPs), both individually and in combination, on the vegetative growth, spore germination, pesticidal activity, and oxidative stress markers like enzymatic antioxidants, catalase, superoxide dismutase, ascorbate peroxidase, and reactive oxygen species generation. Beauveria bassiana was isolated from agricultural fields. A soil sample was used in this study through culture-dependent methods. Toxicity tests reveal that fungal vegetative sporulation and pesticidal activity were highly reduced under high concentrations of heavy metals (both single and combined treatments). Elevated level of reactive oxygen species (ROS) – an important oxidative stress marker in the high concentrations of heavy metals (both single and combined treatments) also reveals the toxicity induced by the heavy metals.

The Ring Oscillator (RO) is a ubiquitous element in the high-speed Phase Locked Loop (PLL) to decide the output frequency for timing controls. Since Digitally Controlled Ring Oscillators (DCRO) with variable output frequency offer more feasibility to the PLL, 3-stage digitally Controlled RO with Complementary Drain Capacitance (CRO-CDC) are presented in this article. The proposed ROs are realized using (i) basic negator, (ii) NAND negator and (iii) NOR negator along with CDC to attain wider tuning range of 440 MHz, 697 MHz and 144 MHz respectively. The proposed CRO-CDC are implemented in 180 nm CMOS technology with supply voltage of 1.8 V and simulated using spectre circuit simulator. The negator RO with CDC (NRO_CDC) achieves variable output frequency ((hbox {f}_{OUT})) of 5.179(-)5.619 GHz consuming power of 786.3 (mu)W. The NAND negator RO with CDC (NdNRO_CDC) exhibits (hbox {f}_{out}) range of 2.729(-)2.873 GHz consuming 944.5 (mu)W. The NOR negator RO with CDC (NrNRO_CDC) attains (hbox {f}_{out}) range of 3.467(-)4.164 GHz and consumes 595 (mu)W. The simulated phase noise (PN) and Figure-of-Merit (FoM) of the proposed CRO-CDC are (-)88.5 dBc/Hz @ 1 MHZ offset and 126.18 dB respectively.

Based on exceptionally well-preserved mid-Cretaceous amber specimens from northern Myanmar, we identified a novel genus and species Elongatus kachinus gen. et sp. nov. (Bostrichidae, Dinoderinae). This classification was established on the basis of distinctive features, including the head being obscured from a top view, the antenna possessing nine segments, the pronotum lacking lateral margins, and occasionally displaying small tubercles at the rear. Additionally, the metatarsi are shorter than the metatibiae, with the final segment of each being equivalent in length to the preceding four segments combined. The unearthing of this new genus not only enhances the fossil record diversity within the Dinoderinae subfamily during the mid-Cretaceous period but also furnishes a valuable fossilized framework for prospective research on the broader evolution and progression of the Bostrichidae family.

Metallic parts working under stringent conditions of creep, fatigue and corrosion when subjected to high temperatures for long durations lead to adverse changes in their structure, leading to unprecedented failures. This demands the development of materials with special surface requirements, apart from developing new materials. This paper envisaged to enable in-situ development of titanium aluminide intermetallic (IMC) on the surface of Al-alloys via friction stir processing coupled with fusion welding – a hybrid approach. Thermal kinetics of the Al-Ti metallurgy significantly depends on precise control of fusion welding speed. For this purpose, a linear slide was developed which could automatically vary and control fusion welding speed. The slide could mount and clamp the welding torch and deposit weld bead at various levels of speeds at a controlled rate. The effect of bead deposit on the in-situ development of titanium aluminide was investigated and a new method for surface development of titanium aluminide on aluminum substrate was assessed and proposed. Results of certain experiments showed increase in hardness upto 155HV and led to the formation of hard phases and potential formation of IMCs in localized regions. It is anticipated that this route could be a promising one, should the numerous parameters be fine-tuned.

The current trend leans towards employing an in vitro-based regenerative approach to tackle the various challenges associated with conventional propagation techniques. Musa acuminata (AAA) cv. Amrit Sagar, native to North-east India, holds substantial nutritional and biological significance. However, its commercial cultivation faces obstacles such as poor sucker quality and biotic pressures. In this study, multiple shoots were obtained using shoot tip explants of M. acuminata cv. Amrit Sagar. These explants were cultured on Murashige and Skoog (MS) solid medium supplemented with varying concentrations of 6-Benzylaminopurine (BAP), adenine sulfate (AdS), and α-Naphthaleneacetic acid (NAA). To facilitate in vitro propagation, surface sterilization was optimized using 4.0% sodium hypochlorite (NaOCl) for 20 min, followed by 0.1% mercuric chloride (HgCl₂) for 20 min, resulting in a contamination rate as low as 13.33%. Shoot regeneration achieved an establishment rate of 87.33% using shoot tips in MS medium with 2.5 mg L^-1 BAP, 40 mg L^-1 AdS, and 0.5 mg L^-1 α-Naphthalene acetic acid (NAA). Optimal multiple shoot formation was observed in MS medium containing 10 mg L^-1 BAP, 40 mg L^-1 AdS, and 0.5 mg L^-1 NAA. Regarding root development, 92.90% efficiency was noted in half-strength MS medium supplemented with 2.5 mg L^-1 Indole-3-butyric acid (IBA).

The bi-directional long short-term memory (Bi-LSTM) is regarded as one of the most promising deep learning algorithms for signal detection in Multiple inputs and Multiple outputs (MIMO) system. The projected algorithm efficiently estimates the channel for several multipath scenarios and enhanced the throughput of system. The simulation results reveal that the projected Bi-LSTM offer a significant Bit error rate (BER) improvement as compared with LSTM, zero forming equalizer (ZFE), minimum mean square error (MMSE) and maximum likelihood (ML) methods for 8 × 8,16 × 16 and 64 × 64 MIMO system with Rayleigh channel.

As nitrogen and weed management in wheat gains prominence for uplifting its productivity, the exploration of alternative nitrogen and weed management options become a priority. In this regard, an experiment was conducted in split plot design with three replications. In main plot, four nitrogen management options were tested: N1 = control, N2 = 100% Recommended Dose of Nitrogen (RDN), N3 = 50% RDN + 2 spray of nano-urea (SNU) (40 & 60 days after sowing– DAS) and N4 = 75% RDN + 1 SNU (60 DAS). Concurrently, four weed management treatments were studied in subplots: W1 = Ready mix of sulfosulfuron + metsulfuron methyl @ 30 + 2 g a.i. ha^− 1 at 30 DAS; W2 = tank mix of clodinafop propargyl @ 60 g a.i. ha^− 1 + carfentrazone-ethyl @ 20 g a.i. ha^− 1 at 30 DAS; W3 = weed free check and W4 = un-weeded check. The results revealed that 100% RDN outperformed 50% RDN + 2-SNU & 75% RDN + 1 SNU in terms of superior soil microbial activity and wheat root growth parameters, ultimately resulting in the maximum grain & straw yield, profitability along with best yield emission trade-offs. Comparing between the two herbicide mixtures, the tank mix of clodinafop + carfentrazone ethyl surpassed the ready mix of sulfosulfuron + metsulfuron methyl in terms of all the above mentioned parameters.

Although several intercropping systems have been reported for cotton, the effects of legume under high-density planting systems on soil biology and nutrient availability in rainfed Vertisol have not yet been studied. With this research gap, we performed a comprehensive evaluation of different legumes (black gram, cluster beans, cowpea, green gram, soybean) in cotton and studied their effects on soil biology and nutrient availability. Legume intercropping in cotton significantly decreased soil pH (4%) and calcium carbonate content (29%), indicating soil acidification. Significant enhancements in soil organic carbon (27%), mineralizable nitrogen (35%), available phosphorus (45%), sulphur (39%), and boron (21%) were observed in cotton + legume intercropping compared with the sole cotton. Legume intercropping significantly increased glomalin (24%), soil polysaccharide (16%), and soil phosphatase activities (58%). Among legumes, soybean and green gram exhibited higher beneficial activities. Overall, our study revealed the beneficial effects of legume-based intercropping in cotton. Among the legumes, soybean and green gram were superior in enhancing soil nutrient availability and biological activities.

Mangroves are crucial ecosystems with significant ecological and socio-economic value; however, they experience global degradation due to threats mainly from anthropogenic activities. Mangrove afforestation is one of the key methods in curtailing these threats. One of the primary challenges in mangrove restoration is the year-round scarcity of propagules. This is mainly due to irregular flowering, insufficient seed viability, insect attacks, poor post-dispersal seed growth, and low germination rates. To address these constraints, efforts have been made to prioritize vegetative propagation. This study assessed the efficacy of using different stem cuttings for mangrove vegetative propagation. Additionally, various growth media (sand, clay, and vermiculite) were examined to determine their potential for supporting the growth of treated cuttings. The presence of phenolic compounds was eliminated from the cuttings prior to the experiment. Various concentrations of auxins, namely indole-3-butyric acid (IBA), naphthalene acetic acid (NAA), and indole acetic acid (IAA), ranging from 1000ppm to 5000ppm, were applied to the stem cuttings. Based on the vigour scale, it was observed that juvenile and semi-hardwood exhibited the highest survival percentage when treated with IBA concentrations between 2000 and 3500 ppm. This study highlights the potential of vegetative propagation as a viable approach to overcome the limitations associated with mangrove restoration.

Litchi is an item of impulse buying, and consumers prefer litchi fruit that is bright red and appealing to the eye. Litchi is exacting in its climatic requirements, and optimal colour development remains a challenge, especially in climes that are far from ideal and shaded portions of the tree canopy. In this study, we tested different bagging combinations involving butter/parchment paper, non-woven polypropylene, polypropylene, high density polyethylene, and black polythene bags, and recorded their effect on colour development and fruit quality in litchi. Our results show how bagging increases red colouration in the pericarp by upto 30%, reduces pest incidence, and improves the overall quality of fruit in litchi. We conclude that optimal fruit quality can be obtained by bagging litchi bunches with a combination of butter paper and polypropylene or non-woven polypropylene bag. Such bright red-coloured litchi fruit with negligible fruit borer infestation can have better consumer acceptability and also fetch better prices for growers.