Manufacture of urea

Urea is in many ways the most convenient form for fixed nitrogen. It has the highest nitrogen content available in a solid fertilizer (46 %). It is easy to produce as prills or granules and easily transported in bulk or bags with no explosive hazard. It leaves no salt residue after use on crops. Its specific gravity is 1.335, decomposes on boiling and is fairly soluble in water. The principal raw materials required for this purpose are NH3 & CO2.Two reactions are involved in the manufacture of urea. First, ammonium carbamate is formed under pressure by reaction between CO2 & NH3. CO2 + 2NH3 NH2COONH4 H= -37.4 Kcal This highly exothermic reaction is followed by an endothermic decomposition of the ammonium carbamate. NH2COONH4 NH2CONH2 + H2O H= + 6.3 Kcal Various processes for the manufacture of urea are: 1) Snamprogetti ammonia stripping process 2) Stamicarbon CO2 stripping process 3) Once through urea process 4) Mitsui Toatsu total recycle urea process We selected the Snamprogetti ammonia stripping process for the manufacture of urea. In this process ammonia & CO2 are compressed & fed to the reactor. The unconverted carbamate is stripped and recovered from the urea synthesis reactor effluent solution at reactor pressure, condensed to an aqueous solution in a steam producing high pressure condenser & recycled back to the reactor by gravity. Part of the liquid NH3 reactor feed, vapourized in a steam heated exchanger, is used as inert gas to decompose & strip ammonium carbamate in the steam heated high pressure stripper. Energy balance & material balance of the plant is done. The selected capacity of the plant is 4,50,000 tons/year of urea producing 62,500 kg/hr of urea with 98 % purity. Urea reactor & vacuum evaporator are designed. The volume of reactor is calculated & found to be 195 m3. The length & diameter of the reactor are 40 m & 2.5 m respectively. The evaporator used is of climbing-film long- tube type. Snamprogetti ammonia-stripping urea process is selected because it involves a high NH3 to CO2 ratio in the reactor, ensuring the high conversion of carbamate to urea. The highly efficient ammonia stripping operation drastically reduces the recycling of carbamate and the size of equipment in the carbamate decomposition . Snamprogetti technology differs from competitors in being based on the use of excess ammonia to avoid corrosion as well as promote the decomposition of unconverted carbamate into urea. Uses of Urea: • About 56 % of Urea manufactured is used in solid fertilizer. • About 31 % of Urea manufactured is used in liquid fertilizer. • Urea-formaldehyde resins have large use as a plywood adhesive. • Melamine-formaldehyde resins are used as dinnerware & for making extra hard surfaces

Forest trees of Odisha, India: An updated checklist

An exhaustive taxonomic inventory of forest trees of Odisha in the Eastern Ghats of India was made during 2015–2020, which revealed the presence of a total of 501 species of wild and naturalised trees belonging to 284 genera under 80 families. The family Euphorbiaceae was the most species-rich represented by 45 species, followed by Rubiaceae (28), Mimosaceae (27), Moraceae (26) and Meliaceae (23). The genus Ficus (Moraceae) had highest number of 21 tree species, followed by Diospyros (10 species), Syzygium (8 species), Albizia (8 species), Senegalia (7 species), Vitex (7 species) and Terminalia (6 species). Nothopodytes nimmoniana, Alphonsea madraspatana, Lasiococca comberi, Siphonodon celastrineus, Searsia paniculata, Syzygium schmidii, Cassipourea ceylanica, Prunus pygeoides, Sonneratia griffithii, Eriolaena hookeriana var. viridis, Dimorphocalyx glabellus, Garcinia xanthochymus and Litsea glutinosa have been identified as regionally threatened species needing conservation intervention. Cocculus laurifolius is reported here as a new distributional record for the state. Field observation on the occurrence and dominance of tree species in different forest types of Odisha has been discussed. A checklist of the tree species of Odisha is presented in this article, along with the correct botanical name, synonym(s), local name, flowering and fruiting time, locality of occurrence and citation of voucher herbarium specimens

Modelling temporal and spatial features of collaboration network

The collaboration network is an example of a social network which has both non-trivial temporal and spatial dependence. Based on the observations of collaborations in Physical Review Letters, a model of collaboration network is proposed which correctly reproduces the time evolution of the link length distributions, clustering coefficients, degree distributions and assortative property of real data to a large extent.Comment: 8 pages, 10 figures; follow up work on arXiv.org/physics/0511181; accepted for publication in IJMP

Evaluation of cervical smear in high risk women

Background: Objectives of current study were (i) To find out the pattern of cervical smear in females having risk factors. (ii) To observe the relationship between abnormal cervical smear with high risk factors.Methods:A cross-sectional descriptive study was carried out in the department of obstetrics and gynecology, Guwahati medical college & hospital from July 2009 to August 2010 with the help of Pathology department. 200 women attending gynecological OPD with associated risk factors were selected at random. Detailed history, demographic information, contraceptive history and coital history were taken. Smear was taken from endocervix with the help of Ayer’s spatula or cytobrush.Results:Out of 200 cases, in 110 (55%) the smear was reported negative for malignancy. 73(36.5%) had an inflammatory smear, 11 (5.5%) had CIN, 1(0.5%) had malignancy and 5(2.5%) the smear was inadequate for cytological examination. In the study mean age of Cervical Intraepithelial Neoplasia (CIN) was 42.64 ± 6.34 years. Low socio-economic status, high parity & the use of oral contraceptive pills were major risk factors.  Conclusion:Cervical smear should be routinely used as a reliable diagnostic aid for early detection carcinoma cervix especially in high risk cases. The need of the hour is to create awareness and easy accessibility to proper screening.

Cross-learning for addressing emergent challenges of aquaculture and fisheries in India

Fisheries and aquaculture play a pivotal role in India’s economy and contributes significantly to the food and nutrition security of the fish-eating population in the country. The sector has recorded an average annual growth rate of 8-10% over the past two decades. The continued vibrancy observed in the fisheries and aquaculture sectors in the country is largely due to the elaborate network of institutions and governance mechanisms that have been developed over years since independence (1947). Both formal and informal networks adorn the fisheries administrative, governance and management regime in India, with their formats diverse in terms of affiliation, ownerships, organizational framework, activity spheres, mode of operation, and so on. This country status paper summarizes the broad architecture of the above network and demonstrates how cross learning among the SAARC member countries could address the regional and sub-regional challenges therein

Emergence of nanoscale inhomogeneity in the superconducting state of a homogeneously disordered conventional superconductor, NbN

The notion of spontaneous formation of an inhomogeneous superconducting state is at the heart of most theories attempting to understand the superconducting state in the presence of strong disorder. Using scanning tunneling spectroscopy and high resolution scanning transmission electron microscopy, we experimentally demonstrate that under the competing effects of strong homogeneous disorder and superconducting correlations, the superconducting state of a conventional superconductor, NbN, spontaneously segregates into domains. Tracking these domains as a function of temperature we observe that the superconducting domains persist across the bulk superconducting transition, Tc, and disappear close to the pseudogap temperature, T*, where signatures of superconducting correlations disappear from the tunneling spectrum and the superfluid response of the system

Gynochthodes cochinchinensis (DC.) Razafim. & B. Bremer (Morindeae: Rubioideae: Rubiaceae): an addition to the woody climbers of India

Gynochthodes cochinchinensis (Rubiaceae), a woody climber, is reported here as a new addition to Indian flora from Similipal Biosphere Reserve, Odisha. The species resembles its closely allied taxon Gynochthodes umbellata, but can be distinguished from it by a number of distinct morphological characters. A detailed description, notes on habitat, ecology and distribution are provided in this paper with color photographs for easy identification

Assessment of ecosystem services of rice farms in eastern India

Authors acknowledge the financial help provided by Ministry of Earth Sciences, Govt. of India and also thank Director General, Indian Council of Agricultural Research (ICAR) and Director, ICAR-National Rice Research Institute (NRRI) for giving all the necessary help in executing the work. The help provided by Odisha state officials in carrying out the survey work is gratefully acknowledged. This study is a part of the project entitled “Delivering food security on limited land (DEVIL; Belmont Forum / FACCE-JPI via NERC: NE/M021327/1).Peer reviewedPublisher PD