Two time constants for the binding of proteins to DNA from micromechanical data

Recent experimental advances allow the direct measurement of the force/extension behavior for DNA in the presence of strongly binding proteins. Such experiments reveal information about the cooperative mechanism of protein binding. We have studied the irreversible binding of such proteins to DNA using a simple simulation and present a method for estimating quantitative rate constants for the nucleation and growth of linear domains of proteins bound to DNA. Such rate constants also give information about the relative energetics of the two binding processes. We discuss our results in the context of recent data for the DNA-recA-ATPγs system, for which the nucleation time is 4.7 × 104 min per recA binding site and the total growth rate of each domain is 1400 recA/min

Bearing Capacity of Interfered Adjacent Strip Footings on Granular Bed Overlying Soft Clay: An Analytical Approach

In the present paper, the interference effects on bearing capacity of two and three closely spaced strip footings resting on granular bed overlying clay are being studied. A simple analytical model is proposed to predict the load-carrying capacity and the interference factor of an interfered footing, when adjacent strip footings are optimally placed on the surface of a Granular Bed (GB) overlying clay and both the footings are simultaneously loaded. A punching shear failure mechanism is envisaged in the analytical model. The load-carrying capacity of the footing is taken as the sum of total shearing resistances along the two vertical planes through the edges of the strip footing in the upper granular layer and the load-carrying capacity of the soft clay beneath the GB. Insights gained from finite element simulations are used to develop the new modified punching shear model for interfering footing. Bearing capacity can be easily calculated by using the proposed punching shear model for interfering footing. The analytical model is validated with numerical analyses and previous experimental results and found to be in reasonably good agreement. The influence of different parameters such as granular bed thickness, width of footing, number of footings are carried out in this study. Doi: 10.28991/cej-2021-03091723 Full Text: PD

Composition and Properties of Fibre Extracted from Pseudostem of Banana (Musa Sp.)

Pseudostem waste from five commercial cultivars of banana was used to extract fibre in order to study its properties. Fibre was extracted by decortification of sheath either manually or using Raspador machine. Yield of fibre in cultivars varied from 0.548% to 0.891%. There was no significant difference in the yield of fibre from different layers of sheath although differences among cultivars were significant. Cellulose was the major component of the fibre at about 60% while lignin levels were nearly 20%. The strength characteristics of Nendran fibre like, mean breaking load, mean breaking extension and tenacity were comparable to those reported for other naturally occurring plant fibres such as pineapple, jute and sisal. The study highlighted the importance of exploiting banana pseudostem after harvest of banana bunch for fibre production on a commercial scale

High contrast imaging and thickness determination of graphene with in-column secondary electron microscopy

We report a new method for quantitative estimation of graphene layer thicknesses using high contrast imaging of graphene films on insulating substrates with a scanning electron microscope. By detecting the attenuation of secondary electrons emitted from the substrate with an in-column low-energy electron detector, we have achieved very high thickness-dependent contrast that allows quantitative estimation of thickness up to several graphene layers. The nanometer scale spatial resolution of the electron micrographs also allows a simple structural characterization scheme for graphene, which has been applied to identify faults, wrinkles, voids, and patches of multilayer growth in large-area chemical vapor deposited graphene. We have discussed the factors, such as differential surface charging and electron beam induced current, that affect the contrast of graphene images in detail.Comment: 5 pages, 4 figure

Open policy for wireless computers in classrooms: What makes it a good or a bad idea?

Increasingly, studies and media articles have been looking into possible adverse effects of open policies for using wireless ready computers in classrooms. Tablet PCs, as indicated by some of those authors, are under suspicion more than laptops because they make it harder for instructor to determine whether they are used productively or for off-the-task purposes. In this study students were invited to voluntarily bring their personal wireless computers to introductory physics classes in order to utilize them with DyKnow software. We compare performance of students who consistently used computers in classroom with those who did so less frequently or not at all. We also gauge how student attitudes and recommendations related to DyKnow software and Tablet PCs vary by the type of computer that was available to them in this course

Comparative antioxidant and antimicrobial studies of cold and hot bark hydromethanolic extract of Couroupita guianensis Aubl

Couroupita guianensis, known by its common name as cannon ball tree, belongs to Lecythidaceae family, native of south and central America, India and Sri lanka. It’s been in use in traditional medicine and worshipped as sacred tree in india. With the importance of tree in various medicinal aspects as per the reports the present investigation was carried to access the phytochemical components, free radical scavenging and antimicrobial activity of cold and hot hydromethanolic extracts from the barks of medicinally important Couroupita guanensis. Phytochemical screening revealed the presence of total antioxidants, flavonoids, phenols and phytosterols in both cold and hot extracts. Quantitative estimations of the phytochemicals revealed the presence of high contents of total antioxidant activity (598.4 µg/ml), phenol content activity of (417.52 µg/ml) and phytosterols of (133.92 µg/ml) in cold hydromethanolic extracts compared to the hot hydromethanolic extract. The presence of high flavonoid content (417.52 µg/ml) was recorded in hot extract compared to the cold extract. Hot extract gave more scavenging activity with IC50 value (33.5 µg/ml). ABTS radical scavenging activity was found to be more in cold extract with IC50 values (24. µg/ml). Antimicrobial assay showed activity with B. cereus (13.00±0.00mm) and S.aureus (15.00±0.00mm) bacteria showed maximum zone of inhibition compared to the hot extract whereas C. albicans (13.00±O.00mm) showing maximum zone of inhibition compared to the cold extract and was not sensitive to any other fungal forms tested. This investigation pays way to consider Couroupita guianensis, with highly potential antioxidant and antimicrobial components, be used in pharmaceutical companies for the development of phytomedicine for the therapy and treatments

FT-IR and Raman vibrational analysis, B3LYP and M06-2X simulations of 4-bromomethyl-6-tert-butyl-2H-chromen-2-one

In this study, the experimental and theoretical vibrational frequencies of a newly synthesized bacteriostatic and anti-tumor molecule namely, 4-bromomethyl-6-tert-butyl-2H-chromen-2-one have been investigated. The experimental FT-IR (4000-400 cm- 1) and Raman spectra (4000-100 cm- 1) of the compound in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parametrized, empirical exchange correlation function) with 6-311++G(d, p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations. © 2014 Elsevier B.V. All rights reserved