We present the fifth release of the UMIST Database for Astrochemistry (UDfA). The new reaction network contains 6173 gas-phase reactions, involving 467 species, 47 of which are new to this release. We have updated rate coefficients across all reaction types. We have included 1171 new anion reactions and updated and reviewed all photorates. In addition to the usual reaction network, we also now include, for download, state-specific deuterated rate coefficients, deuterium exchange reactions and a list of surface binding energies for many neutral species. Where possible, we have referenced the original source of all new and existing data. We have tested the main reaction network using a dark cloud model and a carbon-rich circumstellar envelope model. We present and briefly discuss the results of these models.

The UMIST database for astrochemistry 2012

Hot corino chemistry and warm carbon chain chemistry (WCCC) are driven by gas-grain interactions in star-forming cores: radical-radical recombination reactions to form complex organic molecules (COMs) in the ice mantle, sublimation of CH$_4$ and COMs, and their subsequent gas-phase reactions These chemical features are expected to depend on the composition of ice mantle which is set in the prestellar phase We calculated the gas-grain chemical reaction network considering a layered ice-mantle structure in star-forming cores, to investigate how the hot corino chemistry and WCCC depend on the physical condition of the static phase before the onset of gravitational collapse We found that WCCC becomes more active, if the temperature is lower, or the visual extinction is lower in the static phase, or the static phase is longer Dependence of hot corino chemistry on the static-phase condition is more complex While CH$_3$OH is less abundant in the models with warmer static phase, some COMs are formed efficiently in those warm models, since there are various formation paths of COMs If the visual extinction is lower, photolysis makes COMs less abundant in the static phase Once the collapse starts and visual extinction increases, however, COMs can be formed efficiently Duration of the static phase does not largely affect COM abundances Chemical diversity between prototypical hot corinos and hybrid sources, in which both COMs and carbon chains are reasonably abundant, can be explained by the variation of prestellar conditions Deficiency of gaseous COMs in prototypical WCCC sources is, however, hard to reproduce within our models

Chemical Variation among Protostellar Cores: Dependence on Prestellar Core Conditions

We report the first extragalactic detection of the complex organic molecules (COMs) dimethyl ether (CH3OCH3) and methyl formate (CH3OCHO) with the Atacama Large Millimeter/submillimeter Array (ALMA). These COMs, together with their parent species methanol (CH3OH), were detected toward two 1.3 mm continuum sources in the N 113 star-forming region in the low-metallicity Large Magellanic Cloud (LMC). Rotational temperatures (Trot approx. 130 K) and total column densities (Nrot 10 approx. 16 cm−2) have been calculated for each source based on multiple transitions of CH3OH. We present the ALMA molecular emission maps for COMs and measured abundances for all detected species. The physical and chemical properties of two sources with COMs detection, and the association with H2O and OH maser emission, indicate that they are hot cores. The fractional abundances of COMs scaled by a factor of 2.5 to account for the lower metallicity in the LMC are comparable to those found at the lower end of the range in Galactic hot cores. Our results have important implications for studies of organic chemistry at higher redshift.

The Detection of Hot Cores and Complex Organic Molecules in the Large Magellanic Cloud

Hot corino chemistry and warm carbon chain chemistry (WCCC) are driven by gas-grain interactions in star-forming cores: radical-radical recombination reactions to form complex organic molecules (COMs) in the ice mantle, sublimation of CH$_4$ and COMs, and their subsequent gas-phase reactions. These chemical features are expected to depend on the composition of ice mantle which is set in the prestellar phase. We calculated the gas-grain chemical reaction network considering a layered ice-mantle structure in star-forming cores, to investigate how the hot corino chemistry and WCCC depend on the physical condition of the static phase before the onset of gravitational collapse. We found that WCCC becomes more active, if the temperature is lower, or the visual extinction is lower in the static phase, or the static phase is longer. Dependence of hot corino chemistry on the static-phase condition is more complex. While CH$_3$OH is less abundant in the models with warmer static phase, some COMs are formed efficiently in those warm models, since there are various formation paths of COMs. If the visual extinction is lower, photolysis makes COMs less abundant in the static phase. Once the collapse starts and visual extinction increases, however, COMs can be formed efficiently. Duration of the static phase does not largely affect COM abundances. Chemical diversity between prototypical hot corinos and hybrid sources, in which both COMs and carbon chains are reasonably abundant, can be explained by the variation of prestellar conditions. Deficiency of gaseous COMs in prototypical WCCC sources is, however, hard to reproduce within our models.

Interstellar chemistry in low metallicity environments is crucial to understand chemical processes in the past metal-poor universe. Recent studies of interstellar molecules in nearby low-metallicity galaxies have suggested that the metallicity has a significant effect on chemistry of star-forming cores. Here we report the first detection of a hot molecular core in the extreme outer Galaxy, which is an excellent laboratory to study star formation and interstellar medium in a Galactic low-metallicity environment. The target star-forming region, WB89-789, is located at the galactocentric distance of 19 kpc. Our ALMA observations in 241-246, 256-261, 337-341, and 349-353 GHz have detected a variety of carbon-, oxygen-, nitrogen-, sulfur-, and silicon-bearing species, including complex organic molecules (COMs) containing up to nine atoms, towards a warm (>100 K) and compact (<0.03 pc) region associated with a protostar (~8x10^3 L_sun). Deuterated species such as HDO, HDCO, D2CO, and CH2DOH are also detected. A comparison of fractional abundances of COMs relative to CH3OH between the outer Galactic hot core and an inner Galactic counterpart shows a remarkable similarity. On the other hand, the molecular abundances in the present source do not resemble those of low-metallicity hot cores in the Large Magellanic Cloud. The results suggest that a great molecular complexity exists even in a primordial environment of the extreme outer Galaxy. The detection of another embedded protostar associated with high-velocity SiO outflows is also reported.

The Detection of a Hot Molecular Core in the Extreme Outer Galaxy

Molecules In Space: Physics, Chemistry And Biology

The experiment on low cost hydroponics for growing coriander at laboratory conditions for increasing production per unit area economically. Low cost hydroponics system is the new scientific techniques of growing plants passively without providing mechanical circulations and artificial aerations around the zone of roots. The type of passive technique followed here is modified Kartky system. To illustrate, the experiment was laid down in Completely Randomized Design with five different types of hydroponic nutrient solutions namely: T1 (NPK- 15:15:15 + 1% Calcium Nitrate + 1% Magnesium Sulfate), T2 (NPK – 15:15:15 + 0.5% Calcium Nitrate + 0.5% Magnesium Sulfate), T3 (NPK- 20:20:20 +1% Calcium Nitrate + 1% Magnesium Sulfate), T4 (NPK- 20:20:20 + 0.5% Calcium Nitrate + 0.5% Magnesium Sulfate), T5 (Water). These five independent treatments had 4 replications each. Furthermore, 30% buffered and sterilized coco peat was filled along with seeds on each hydroponics cup. Accordingly, the major observations were taken on 10, 20 & 30 Days after sowing on the basis of specific parameters such as: number of leaves, length of leaves, number of rootlets, length of rootlets, total length of the seedlings and chlorophyll content. To summarize in the end, it was concluded that T2 (NPK- 15:15:15+ 0.5% calcium nitrate + 0.5 % magnesium sulfate) reported to be the best nutrient treatment solutions with higher germination rate, good root architecture, higher chlorophyll content and other parameters.

/pdf/use-of-low-cost-hydroponics-technique-for-growing-coriander-93rn2z6u.pdf

Use of Low Cost Hydroponics Technique for Growing Coriander at Laboratory Conditions

Abstract: Bengali or Bangalee is someone whose linguistic, cultural and ancestral origin is belonged to Bengal.in this study the two broader communities were taken under observations. The identity of both communities was elaborated, the origin and evolution along with present existence was discussed. The food culture and food habits pertained by both communities were generalised with some specifications of categorizations in food intake. It was observed that Bangals and Ghatis. Matrimonial relation between two communities has helped mixing the food culture in many ways. Other than that curiosity and urge of experimenting with food has impacted the food habits of both the sides. In long term it was found that the two distinguished communities are dealing and facing certain type of health issues and severe diseases or illness just because of unplanned and unaware healthy food intake. In the case of lifestyle both the communities acquire few different lifestyles to improve their previous circumstances, mainly the rural areas where food is still under the grasp of superstitions.

/pdf/a-study-on-food-habits-food-culture-impacting-health-and-1as1yfd9.pdf

A Study on Food Habits, Food Culture, Impacting Health and Lifestyles among Two Communities of West Bengal

Multi-track multi-layer friction stir additive manufacturing of AA6061-T6 alloy

Hybrid Additive Manufacturing (HAM) technologies leverage the strength of Additive Manufacturing (AM) and Subtractive Manufacturing (SM) in fabricating complex geometries with precision. Friction Stir Welding (FSW) has been acknowledged for joining sheets of similar or dissimilar materials with improved mechanical/metallurgical properties. However, due to the inherent pinhole defect and complicated toolpath planning, this process has not been explored much for fabricating the objects in a layer-by-layer manner. Therefore, this work investigates Computer Aided Process Planning (CAPP) for realizing fully functional metallic parts through a HAM system. This HAM system uses a Sheet Lamination (SL) process, i.e. Friction Stir Additive Manufacturing (FSAM), synergistically coupled with an SM process, i.e. machining. To realize complicated geometries through the proposed HAM system, three different build strategies are developed viz. Near-net block fabrication, Near-net shape fabrication via ‘form-then-bond approach’ and ‘bond-then-form approach.’ Each build strategy consists of a detailed CAPP that includes toolpath planning, tooling aspects, simulated outcome and so on. Further, these build strategies are discussed for realizing the parts with Functionally Graded Materials (FGM) & embedded structures. Finally, a monolithic object of aluminium has been fabricated as a case study to demonstrate one of the aforementioned build strategies. 

Different build strategies and computer-aided process planning for fabricating a functional component through hybrid-friction stir additive manufacturing

Ankan Das

Papers

Molecules In Space: Physics, Chemistry And Biology

Use of Low Cost Hydroponics Technique for Growing Coriander at Laboratory Conditions

A Study on Food Habits, Food Culture, Impacting Health and Lifestyles among Two Communities of West Bengal

Multi-track multi-layer friction stir additive manufacturing of AA6061-T6 alloy

Different build strategies and computer-aided process planning for fabricating a functional component through hybrid-friction stir additive manufacturing