Ravi Gautam

National Institute for Materials Science

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R. Gopalan

International Advanced Research Centre for Powder Metallurgy and New Materials

D. Prabhu

International Advanced Research Centre for Powder Metallurgy and New Materials

Sachin S. Suroshe

Indian Agricultural Research Institute

Sudhida Gautam

University of Delhi

Babasaheb B. Fand

Central Institute for Cotton Research

V. Chandrasekaran

International Advanced Research Centre for Powder Metallurgy and New Materials

H. Sepehri‐Amin

National Institute for Materials Science

Md. Aslam Khan

T. Ohkubo

National Institute for Materials Science

Hosei Nagano

Nagoya University

Cooperative Institutions

Indian Agricultural Research Institute

National Institute for Materials Science

International Advanced Research Centre for Powder Metallurgy and New Materials

Indian Council of Agricultural Research

Indian Institute of Technology Madras

University of Tsukuba

Indian Institute of Science Bangalore

Nagoya University

University of Delhi

Spintronics Research Network of Japan

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Designing flexible hard magnetic materials for zero-magnetic-field operation of the anomalous Nernst effect

arXiv (Cornell University) (2024)

Sang J. Park Rajkumar Modak Ravi Gautam Abdulkareem Alasli Takamasa Hirai

The global shift towards a carbon-neutral society has accelerated the demand for green energy, driving research into efficient technologies for harvesting energy from low-grade waste heat. Recently, transverse thermoelectrics based on the anomalous Nernst effect (ANE) has gained attention due to their simple device structure, scalability, and manufacturing-friendly nature. While topological single crystals and epitaxial films have been focused for enhancing the ANE-driven thermoelectric performance, further improvements in material design are necessary for practical applications. Here, we report an easy-to-implement strategy for designing mechanically flexible and magnetically hard transverse thermoelectric materials by creating amorphous-crystalline heterogeneous composites. We fabricated and optimized the heterogeneous composites through controlled heat treatment, achieving significant enhancements in the coercivity and anomalous Nernst coefficient, while maintaining flexibility. Additionally, using the developed material, we constructed a single-material-based coiled device and demonstrated the zero-field operation of the ANE-based energy harvesting from curved heat sources. These results validate the feasibility of using the ANE-based flexible materials for energy harvesting applications.

Nernst effect

Zero (linguistics)

10.48550/arxiv.2412.08853

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Screening of Parthenium hysterophorus as phago-stimulant against Zygogramma bicolorata (Chrysomelidae: Coleoptera)

Journal of Entomological Research (2006)

Ravi Gautam Md. Aslam Khan C.P.N. Gautam Bishwajeet Paul

Maximum feeding and development of grubs and adults of Zygogramma bicolorata was noticed on tender leaves of P. hysterophorus followed with composit feed (mixture of inflorescence, tender leaf, mature leaf), which also represented control. Feeding on inflorescence was not suitable for insect's breeding, as scanty eggs laid initially by field-collected beetles did not hatch.

Parthenium hysterophorus

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Comparative Life Table Analysis of Chrysopids Reared on Phenacoccus solenopsis Tinsley in Laboratory

Journal of Biological Control (2009)

Sudhida Gautam A. K. Singh Ravi Gautam

Life tables of two chrysopid predators, viz., Chrysoperla sp. (carnea-group) and Mallada desjardinsi (Navas) on the invasive mealybug, Phenacoccus solenopsis (also reported as P. solani ), were prepared in the laboratory to determine the efficacy of the predators as biocontrol agents of the pest. The rate of mortality (qx) during 0-7 days age interval was higher in Chrysoperla sp. (carnea-group) (0.28) than in M. desjardinsi (0.22) while it was reverse during 70-77 days age interval when reared on P. solenopsis . In fact, qx was higher in M. desjardinsi (2.50) than in Chrysoperla sp. (carnea-group) (0.00). The rate of multiplication per day was 0.1159 and 0.1414 females/female for Chrysoperla sp. (carnea-group) and M. desjardinsi , respectively. The intrinsic rate of increase (rm) was found to be 0.11 for both the predators. Chrysoperla sp. (carnea-group) population multiplied 62.80 times in a generation time of 35.72 days on the mealybug, whereas M. desjardinsi multiplied 67.12 times in a time period of 29.75 days. Life table assays help in estimating the total number of the natural enemies to be released in biological control programmes. This study would be of paramount importance in estimating the total number of the natural enemies to be released in biological control programmes against the mealybug, which is exotic.

Chrysoperla carnea

Mealybug

10.18641/jbc/23/4/46093

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Olfactory responses of green lacewings, Chrysoperla sp. (carnea group) and Mallada desjardinsi on mealybug, Phenacoccus solenopsis (Homoptera: Pseudococcidae) fed on cotton.

Acta Entomologica Sinica (2010)

Sudhida Gautam Archana Singh Ravi Gautam

Mealybug

Chrysoperla carnea

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Life table analysis of the mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) under laboratory conditions.

Journal of Entomological Research (2010)

Babasaheb B. Fand Ravi Gautam Subhash Chander Sachin S. Suroshe

Results on age specific cohort life table on Phenacoccus solenopsis Tinsley at 27 ± 2°C and 65 ± 5% RH revealed that, the maximum female fertility was 140.69 female nymphs/female/week during the 5th age interval (28–35 days). The gross reproductive rate (GRR) was 242.07 females/female/generation while the net reproductive rate (R0) was 123.41 females/female/generation. Mean generation time (T), the intrinsic rate of natural increase (rm) and finite rate of increase () were 28.34 days, 0.1699 females/female/day and 1.185 females/female/day, respectively. The mortality rate was relatively higher for the first instar crawlers, which declined sharply in subsequent instars. The life cycle duration was 27.25 ± 0.5 days at 27 ± 2°C and 65 ± 5% RH. The female produced on an average 351 ± 44.73 young ones in her ovipositional period of 11.75 ± 0.96 days.

Mealybug

Population Dynamics

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Mass Multiplication of Chrysoperla carnea (Stephens) on Non Traditional Hosts

Annals of Plant Protection Sciences (2005)

CP Viji Ravi Gautam

Studies were carried out in search of an alternate host, which was ecofriendly and easy to mass-produce the predator. Tribolium castaneum larva and Drosophila melanogaster larva were identified as better alternate hosts for mass multiplication of the predator. Chrysoperla carnea larva reared on T. castaneum larvae underwent a high incubation period (5.25-6.13 days), high prepupal period (1.13-1.89 days) and pupal period (10.88-13.50 days) compared to those fed with Corcyra cephalonica eggs which remained in incubation for 3.79-4.83 days, with prepupal and pupal period of 0.29-0.84 and 7.66-9.13 days, respectively. Larval period (7.50-8.75 days) was however, significantly at par. Highest adult longevity (females- 46.00 to 54.54 days, male- 25.13 to 35.38 days) and fecundity (881.80 to 1061.00 eggs) was observed when larvae were fed with T. castaneum larvae. When C. cephalonica was used as a larval diet, adult longevity varied from 23.50-28.71 for males and 34.50-44.43 for females. Fecundity ranged from 505.83-770.57 during different generations. Even though, D. melanogaster larva, proved as an inferior host compared to C. cephalonica eggs, could be recommended as a better alternate host because of its fast multiplication, cheaper production and harmlessness to workers.

Chrysoperla carnea

Incubation period

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Advances in soilless cultivation technology of horticultural crops: Review

The Indian Journal of Agricultural Sciences (2022)

Ravi Gautam Pramod Singh Prabhat Kumar Raman Selvakumar Mahendra Singh

The burgeoning population and climate change posing a challenge to meet the sufficient and quality food, fodder and fuel demand in 2050.The cultivable land is also shrinking due to industrialization and urbanization as the availability was 0.50 ha in 1960 which has come down at 0.25 ha. The continuous intensive agriculture led to poor soil health. The demand of food, fodder and fuel is ever rising with rise in population therefore; it is very difficult to sustain supply with present cultivation practices under climate change regime. To overcome this problem, soilless culture is one of the best alternatives. Soilless culture is a novel methodology for growing of crops or plants without soil by using growing media which can be solid, liquid, organic or inorganic material. One of the major advantages of soilless media is saving of water up to 85-90%, as water is recycled and provide better yield as compared to conventional cultivation with almost zero environmental pollution. Plug tray nursery raising using soilless medium is being done on commercial scale at many places. Research on Soilless cultivation is being carried out at Indian Agricultural Research Institute, Pusa, New Delhi since 2016. Hydroponic has been emerged as a new technique to grow plants in recent era. Aeroponics is one of the most successful and rapid methods of seed potato production in which large numbers of mini tubers can be produced in one generation which reduces time and cost. Plants grown in soil less culture are of superior quality with high yield, rich in nutrient content and rapid harvest as compared to conventional cultivation/soil. The growing conditions are generally regulated resultantly a robust resilient production system may be developed for continued supply of vegetables/fruits/flowers, it can synergistically add in total production.

Hydroponics

Fodder

10.56093/ijas.v91i4.112621

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Comparative effect of formulated kairomonal dusts on parasitization efficiency of Trichogramma spp.

Journal of Environmental Biology (2017)

Madhulika Srivastava A. K. Singh Sudhida G. Parihar Ravi Gautam V. Kumar

Trichogramma

10.22438/jeb/38/4/mrn-288

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Satellite to field: GIS and remote sensing in agriculture and allied sector

International Journal of Research in Agronomy (2024)

Ravi Gautam sandeep sandeep Reetika Praveen Kumar Singh Luxmi Sharma

10.33545/2618060x.2024.v7.i8i.1343

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Effect of substrata and age of Menochilus sexmaculata (Fabr.) (Coleoptera: Coccinellidae) on its oviposition.

Journal of Biological Control (1990)

Ravi Gautam

Adults of Menochilus sexmaculata (Fabr.) reared on the striped mealybug, Ferrisia virgata (Cockerell) showed no particular preference to different substrata Viz ., jar surface, tissue paper or potato as indicated by the percentage of egg-laying which was 36.51, 36.23 and 29.10, respectively. However, when fed on aphids [ Lipaphis erysimi (Kalt.) and Aphis gossypit Glover] it preferred to lay maximum eggs (71.75%) on cotton twigs. Rearing of M. sexmaculata either on mealybug using tissue paper or aphids with cotton twigs as substrata upto 4th week (Productive age) may be adopted as 73.44-81.47 % eggs with 91.35-100.00 % hatching are obtained In this period. Thereafter, adults may be discarded In order to save laboratory host.

Lipaphis erysimi

Mealybug

Aphis gossypii

10.18311/jbc/1990/15326

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