558 research outputs found
TiO2 nanoparticle biosynthesis and its physiological effect on mung bean (Vigna radiata L.)
AbstractTiO2 nanoparticle (NPs) biosynthesis is a low cost, ecofriendly approach developed using the fungi Aspergillus flavus TFR 7. To determine whether TiO2 NPs is suitable for nutrient, we conducted a two part study; biosynthesis of TiO2 NP and evaluates their influence on mung bean. The characterized TiO2 NPs were foliar sprayed at 10mgL−1 concentration on the leaves of 14 days old mung bean plants. A significant improvement was observed in shoot length (17.02%), root length (49.6%), root area (43%), root nodule (67.5%), chlorophyll content (46.4%) and total soluble leaf protein (94%) as a result of TiO2 NPs application. In the rhizosphere microbial population increased by 21.4–48.1% and activity of acid phosphatase (67.3%), alkaline phosphatase (72%), phytase (64%) and dehydrogenase (108.7%) enzyme was observed over control in six weeks old plants owing to application of TiO2 NPs. A possible mechanism has also been hypothesized for TiO2 NPs biosynthesis
Duration of low temperature changes physiological and biochemical attributes of rice seedling
Received: June 2nd, 2022 ; Accepted: August 4th, 2022 ; Published: August 18th, 2022 ; Correspondence: [email protected] low temperature (LT) is detrimental to growth of rice seedling during boro season
in Bangladesh. An experiment was conducted in growth chamber during June to October, 2021
using BRRI dhan29 as planting material. The aim of this experiment was to determine the effect
of variable duration of LT on growth, physiological and biochemical traits of rice seedling and to
determine the age of seedling that can tolerate cold effect. In this experiment 5, 10, 15 and 20
days old seedling (DOS) were exposed to 6 °C for 1, 2, 3 and 4 days. Seedlings were also grown
under room temperature (25 °C, RT) which consider as control treatment. Seedlings were grown
in plastic trays filled with mixture of soil and cowdung. The experiment was conducted following
completely randomized design with 3 replications. Data on shoot length and weight, root length
and weight, chlorophyll (Chl), carotenoids, malondialdehyde (MDA) and proline contain were
determined after 5 days of temperature sock. The results revealed that the LT was injurious to
younger rice seedling when they were exposed to LT for 1 to 2 days. The shoot and root length
as well as their dry weight were reduced under low temperature. Further, the Chl and carotenoid
content of younger rice seedlings degraded within 2 days of LT exposure. On the contrary, the
proline and MDA content of rice seedlings increased to reduce the harmful effect of under LT. It
could be concluded that the rice seedlings could tolerate the detrimental effect of LT when they
attain at least 15 days
Rice growth and yield characteristics under elevated carbon dioxide and nitrogen management
Received: July 16th, 2022 ; Accepted: September 8th, 2022 ; Published: September 12th, 2022 ; Correspondence: [email protected] atmospheric carbon dioxide (CO2) concentration is increasing and the on crop
production needs to be investigated. A pot experiment was conducted in open top chambers
(OTC) to determine the response of rice to elevated CO2 (eCO2) under varying time of nitrogen
(N) application. The results revealed that photosynthesis, root and shoot dry matter production,
yield components and nutrient absorption were favored at eCO2 when N applied up to flowering
stage (FT) of rice. However, the N application up to FT of rice also significantly improved percent
filled grain, reduce spikelet sterility and rice yield increased by 18 to 20% under eCO2. Rice plant
absorbed higher amount of Zn, Ca, Mg, and Fe at eCO2 when N was applied up to FT. Amylose
was higher but protein percentage was lower at eCO2. These results indicate that to maximize rice
yield under eCO2, it is important to supply N up to FT of rice in order to increase grain fertility
and reduce spikelet sterility
Rescheduling of wet season (T. Aman) rice planting for cropping intensification in coastal Bangladesh
About 1.0 million ha coastal lands in Bangladesh are mono-cropped suffer from varying degree of soil salinity, waterlogging and climate vulnerability. Low yielding, traditional T. Aman rice is grown only in wet season. Growing non-rice crop after late harvested T. Aman rice is not profitable. This study was aimed to introduce high yielding, short duration T. Aman rice varieties for advancing its harvesting time and to make the avenue for timely establishment of dry season crops. Varietal trials were made at Dacope and Amtali under ACIAR funded project during 2016-2018 and compared with local cultivars. Among tested varieties BRRI dhan76 followed by BRRI dhan77 and BRRI dhan54 in Dacope and BRRI dhan77 followed by BRRI dhan76 and BRRI dhan54 in Amtali were preferred for 0.5–1.0 tha−1 yield advantage and 15–25 days earliness compared to traditional varieties. Early harvesting of T. Aman created the avenue of timely establishment of rice and non-rice crops depending on availability of fresh water and thus crop intensification and land productivity was improved. The new cropping system increased annual rice yield and farmers’ profits by 1.5- to 2-folds compared with traditional system without environmental degradation. This technique can be replicated in similar coastal zones of Bangladesh
Uniaxial Phase Transition in Si : Ab initio Calculations
Based on a previously proposed thermodynamic analysis, we study the relative
stabilities of five Si phases under uniaxial compression using ab initio
methods. The five phases are diamond, beta-tin, sh, sc, and hcp structures. The
possible phase-transition patterns were investigated by considering the phase
transitions between any two chosen phases of the five phases. By analyzing the
different conributions to the relative pahse stability, we identified the most
important factors in reducing the phase-transition pressures at uniaxial
compression. We also show that it is possible to have phase transitions occur
only when the phases are under uniaxial compression, in spite of no phase
transition when under hydrostatic commpression. Taking all five phases into
consideration, the phase diagram at uniaxial compression was constructed for
pressures under 20 GPa. The stable phases were found to be diamond, beta-tin
and sh structures, i.e. the same as those when under hydrostatic condition.
According to the phase diagram, direct phase transition from the diamond to the
sh phase is possible if the applied uniaxial pressures, on increasing, satisfy
the condition of Px>Pz. Simiilarly, the sh-to-beta-tin transition on
increeasing pressures is also possible if the applied uniaxial pressures are
varied from the condition of Px>Pz, on which the phase of sh is stable, to that
of Px<Pz, on which the beta-tin is stable
Electronic Structure of Dangling Bonds in Amorphous Silicon Studied via a Density-Matrix Functional Method
A structural model of hydrogenated amorphous silicon containing an isolated
dangling bond is used to investigate the effects of electron interactions on
the electronic level splittings, localization of charge and spin, and
fluctuations in charge and spin. These properties are calculated with a
recently developed density-matrix correlation-energy functional applied to a
generalized Anderson Hamiltonian, consisting of tight-binding one-electron
terms parametrizing hydrogenated amorphous silicon plus a local interaction
term. The energy level splittings approach an asymptotic value for large values
of the electron-interaction parameter U, and for physically relevant values of
U are in the range 0.3-0.5 eV. The electron spin is highly localized on the
central orbital of the dangling bond while the charge is spread over a larger
region surrounding the dangling bond site. These results are consistent with
known experimental data and previous density-functional calculations. The spin
fluctuations are quite different from those obtained with unrestricted
Hartree-Fock theory.Comment: 6 pages, 6 figures, 1 tabl
Build-up and decline of organic matter during PeECE III
Increasing atmospheric carbon dioxide (CO2) concentrations due to anthropogenic fossil fuel combustion are currently changing the ocean's chemistry. Increasing oceanic [CO2] and consequently decreasing seawater pH have the potential to significantly impact marine life. Here we describe and analyze the build-up and decline of a natural phytoplankton bloom initiated during the 2005 mesocosm Pelagic Ecosystem CO2 Enrichment study (PeECE III). The draw-down of inorganic nutrients in the upper surface layer of the mesocosms was reflected by a concomitant increase of organic matter until day t11, the peak of the bloom. From then on, biomass standing stocks steadily decreased as more and more particulate organic matter was lost into the deeper layer of the mesocosms. We show that organic carbon export to the deeper layer was significantly enhanced at elevated CO2. This phenomenon might have impacted organic matter remineralization leading to decreased oxygen concentrations in the deeper layer of the high CO2 mesocosms as indicated by deep water ammonium concentrations. This would have important implications for our understanding of pelagic ecosystem functioning and future carbon cycling
Possible Z2 phase and spin-charge separation in electron doped cuprate superconductors
The SU(2) slave-boson mean-field theory for the tt'J model is analyzed. The
role of next-nearest-neighbor hopping t' on the phase-diagram is studied. We
find a pseudogap phase in hole-doped materials (where t'<0). The pseudo-gap
phase is a U(1) spin liquid (the staggered-flux phase) with a U(1) gauge
interaction and no fractionalization. This agrees with experiments on hole
doped samples. The same calculation also indicates that a positive t' favors a
Z2 state with true spin-charge separation. The Z2 state that exists when t' >
0.5J can be a candidate for the pseudo-gap phase of electron-doped cuprates (if
such a phase exists). The experimental situation in electron-doped materials is
also addressed.Comment: 6 pages, 2 figures, RevTeX4. Homepage http://dao.mit.edu/~wen
Microfluidic and Nanofluidic Cavities for Quantum Fluids Experiments
The union of quantum fluids research with nanoscience is rich with
opportunities for new physics. The relevant length scales in quantum fluids,
3He in particular, are comparable to those possible using microfluidic and
nanofluidic devices. In this article, we will briefly review how the physics of
quantum fluids depends strongly on confinement on the microscale and nanoscale.
Then we present devices fabricated specifically for quantum fluids research,
with cavity sizes ranging from 30 nm to 11 microns deep, and the
characterization of these devices for low temperature quantum fluids
experiments.Comment: 12 pages, 3 figures, Accepted to Journal of Low Temperature Physic
Looking Beyond Inflationary Cosmology
In spite of the phenomenological successes of the inflationary universe
scenario, the current realizations of inflation making use of scalar fields
lead to serious conceptual problems which are reviewed in this lecture. String
theory may provide an avenue towards addressing these problems. One particular
approach to combining string theory and cosmology is String Gas Cosmology. The
basic principles of this approach are summarized.Comment: invited talk at "Theory Canada 1" (Univ. of British Columbia,
Vancouver, Canada, June 2 - 4, 2005) (references updated
- …