Laboratory system for optical coherence tomography (OCT) using a laser plasma source of soft x-rays and extreme ultraviolet and focusing ellipsoidal optics.

Optical coherence tomography (OCT) with the use of soft x-rays (SXR) and extreme ultraviolet (EUV) has been recently demonstrated [Fuchs et al. Sci. Rep.6, 20658 (2016)10.1038/srep20658; Fuchs et al. Optica4, 903 (2017)10.1364/OPTICA.4.000903]. This new imaging technique, named XCT, makes it possible to obtain cross-sectional and tomographic images of objects with nanometer spatial resolution. The article presents a newly developed laboratory system for XCT using a compact laser plasma light source operating in the SXR and EUV spectral ranges. The source is based on a gas puff target containing Kr gas or a Kr/Xe gas mixture irradiated with nanosecond laser pulses from an Nd:YAG laser. The use of the gas puff target enables efficient emission of SXR and EUV radiation without generating target debris associated with laser ablation when using a solid target. The system is equipped with an ellipsoidal mirror to collect radiation from the source and focus on the imaged object. The XCT measurements are made by processing the spectrum of the radiation reflected from the object recorded with a transmission grating spectrometer equipped with an identical focusing mirror and a CCD camera. The paper presents the characterization and optimization of the new XCT system and its application to the measurements of layered nanostructures.

Cellular and molecular immune response and production performance of Indian white shrimp Penaeus indicus (H. Milne-Edwards, 1837), reared in a biofloc-based system with different protein levels of feed.

The present study focuses on the immunity and growth of Penaeus indicus fed with varying protein levels (25%, 30%, and 35%) in a biofloc based rearing system. A 120 days growth trial was carried out using juvenile Penaeus indicus (0.71 ± 0.01) with dietary protein level, 25% (LP), 30% (MP), and 35% (HP), and a control diet-fed with 35% acted as control group resulting in 4 treatments each with four replicates and were randomly assigned 16 tank units (7500 L each). A combination of different carbon sources (molasses, wheat flour, and rice bran in 2:1:1 ratio), yeast and a probiotic (Bacillus sp.) consortium were used for the development of biofloc. At the end of the trial, the growth parameters of shrimps viz., initial weight, feed conversion ratio (FCR), and daily growth coefficient (DGC) were computed. The results indicated that shrimp fed with medium (30%) protein (MP) diet recorded significantly (P < 0.05) improved growth performance compared to high protein fed group (35%) and low protein (25%) fed group (LP) in a biofloc system and control group (35%). The immunological parameters such as hemagglutination activity (HA) assay, serum protein, lysozyme, phenol oxidase (PO), and inhibition of superoxide dismutase (SOD) activity were observed in serum, plasma, and hemocyte lysate supernatant (HLS). The HA activity, PO activity in plasma was found to be higher in high protein fed animals, whereas medium protein resulted in enhanced PO activity in serum. Similarly, lysozyme and SOD were inhibited well in high protein fed animals compared to the low protein fed group. The vital immune genes's mRNA profiling showed a potential rise in the expressional pattern in MP and HP treatments compared to LP and control. BGBP (beta-1,3-glucan binding protein) and hemocyanin mRNA transcript levels were highly upregulated in the HP (5 fold) and moderately expressed in MP (2 fold) and LP (1-2 fold). The transcripts of peroxinectin, antimicrobial peptides like crustin showed significant upregulation in HP followed by in MP and LP and control. Likewise, other immune genes, such as SOD, prophenoloxidase (proPO), showed a similar trend in a marginal way, indicating immunomodulation in the biofloc groups. This study suggested that biofloc with high protein (35%) supplementation can substantially enhance the immune response of shrimps, although medium protein level (30%) is optimum for improving the survival, growth, and in turn economic return in Indian white shrimp.

Prospective impact of Corona virus disease (COVID-19) related lockdown on shrimp aquaculture sector in India - a sectoral assessment.

The lockdown on account of the Coronavirus disease 2019 (COVID-19) adversely impacted the food production sector including aquaculture, globally. Unfortunately, it coincided with the major shrimp farming season in India which contributes 60% of the national annual shrimp production hence the impact was substantial. An on-line survey was carried out among the stakeholders of the shrimp farming sector to evaluate the prospective impact of COVID-19 related lockdown across the shrimp supply chain. The study estimated an economic loss of 1.50 billion USD to the shrimp aquaculture sector during the current year. It is expected that shrimp production and its export performance may be declining by 40% in the current season. The Garret ranking and Rank Based Quotient analyses projected severe constraints in shrimp seed production and supply, disruptions in the supply chain, logistics, farming, processing, marketing and loss of employment and income for the workers due to the pandemic. To mitigate the impact, the Government of India declared fisheries and aquaculture as an essential activity, facilitated the movement of inputs and services. Further, a major Fisheries Development Scheme(PMMSY) with a financial outlay of 267 million USD has been announced to usher in a blue revolution by strengthening the value chain, doubling the fisher/farmer income, employment generation, economic and social security for fishers/fish farmers adhering to the sustainability principles. Short and medium-term technical and policy measures are suggested to tide over the impact of COVID-19 related lockdown and related restrictions.