Symmetry-based pulse sequences in solid-state NMR and applications to biological systems

We present some applications of solid-state nuclear magnetic resonance to model compounds and biological systems. We highlight a class of pulse sequences that are designed based on symmetry properties of the internal spin interactions. Examples are given showing resonance assignments, determination of internuclear distances, and torsion angle determinations in representative model systems as well as true biological systems

SOUND SPECTRUM MEASUREMENTS IN DUCTED AXIAL FAN UNDER STABLE CONDITION AT FREQUENCY RANGE 6000 TO 6600 HZ

Performance of axial fan is found to reduce drastically when instability is encountered during its operation. Performance of an axial fan is severely impaired by many factors mostly related to system instabilities due to rotating stall and surge phenomenon experienced during its operation. The present work involves measuring the sound spectrum measurements in ducted axial fan under stable condition at frequency range from 6000 to 6600 Hz. Objective of the experiment is to measure the frequency domain signal and study the sound Characteristics in ducted axial fan by using spectrum analyser. Different types of FFT signals have been measured under stable condition for the frequency range of 6000 Hz to 6600 Hz with respect to rotor speed and different graphs are plotted for ducted axial fan

Comparative Analysis of Velocity Measurements In Ducted Axial Fan

The paper deals with experimental investigation and comparative analysis of velocity measurements in ducted axial fan. Experiments were carried out to investigate the nature of velocity variations in a ducted axial fan at different throttle positions as a function of rotor speed employing both Pitot tube and Hot Wire Anemometer. Quantitative analyses of the magnitudes of velocity measured by a pitot tube as well as a hot wire anemometer are examined and various graphs have been plotted. The percentage errors of velocity level have been determined

A comparative study of radical radiotherapy with weekly paclitaxel versus radical radiotherapy with weekly cisplatin in the management of locally advanced squamous cell carcinomas of head and neck

Background: Concurrent chemo radiation is standard of care in locally advanced squamous cell carcinomas of head and neck. Single agent Cisplatin either weekly or three weekly is commonly used concurrently with radiation. The present study aims to evaluate the response rate and toxicity of radical radiotherapy with weekly paclitaxel and cisplatin in head and neck cancers.Methods: This is a prospective double arm study in which sixty patients with histologically proved squamous cell carcinomas registered in our department were accrued into the study with thirty patients in each arm. All patients were treated using Theratron phoenix 780 cobalt unit with a dose of 66 Gy in 33 fractions. The patients were randomized to receive 40 mg/m2 of weekly cisplatin or 40 mg/m2 of weekly Paclitaxel concurrently with radiation. The response to the therapy was assessed six weeks after completion of treatment. The statistical analysis was done using SPSS software.Results: In cisplatin group 18 patients achieved complete response and 12 patients achieved partial response whereas in Paclitaxel group 21 patients achieved complete response and 9 patients achieved partial response. However in paclitaxel arm the incidence of radiation dermatitis, mucositis, dysphagia and laryngitis are slightly higher compared to cisplatin group.Conclusions: The weekly paclitaxel concurrent with radiation is a feasible alternative to weekly cisplatin in locally advanced squamous cell carcinomas of head and neck

Multiplexing experiments in NMR and multi-nuclear MRI

Multiplexing NMR experiments by direct detection of multiple free induction decays (FIDs) in a single experiment offers a dramatic increase in the spectral information content and often yields significant improvement in sensitivity per unit time. Experiments with multi-FID detection have been designed with both homonuclear and multinuclear acquisition, and the advent of multiple receivers on commercial spectrometers opens up new possibilities for recording spectra from different nuclear species in parallel. Here we provide an extensive overview of such techniques, designed for applications in liquid-and solidstate NMR as well as in hyperpolarized samples. A brief overview of multinuclear MRI is also provided, to stimulate cross fertilization of ideas between the two areas of research (NMR and MRI). It is shown how such techniques enable the design of experiments that allow structure elucidation of small molecules from a single measurement. Likewise, in biomolecular NMR experiments multi-FID detection allows complete resonance assignment in proteins. Probes with multiple RF microcoils routed to multiple NMR receivers provide an alternative way of increasing the throughput of modern NMR systems, effectively reducing the cost of NMR analysis and increasing the information content at the same time. Solidstate NMR experiments have also benefited immensely from both parallel and sequential multi-FID detection in a variety of multi-dimensional pulse schemes. We are confident that multi-FID detection will become an essential component of future NMR methodologies, effectively increasing the sensitivity and information content of NMR measurements. (c) 2021 Elsevier B.V. All rights reserved

Future Armour Materials and Technologies for Combat Platforms

The ultimate goal of armour research is to create better armour for battle worthy combat plat forms such as main battle tanks, infantry combat vehicles and light combat vehicles. In each of these applications, the main aim boils down to one of the two things; either reduce the weight without sacrificing protection or enhance the performance at same or even reduced weight. In practice, these ambitions can be fulfilled only if we have with us, appropriate improved armour materials, advanced and innovative technologies and also improved designs, which enable us to use them for creating next generation armour modules. Armour systems have progressed through improvements in metallic, ceramic and lightweight (low areal density) composite materials. Similarly, the advances in development of explosive reactive armour (ERA) and non-explosive reactive armour (NERA) have generated efficient armour system against contemporary high explosive antitank ammunition and missile threats for the armoured vehicles. Yet, to achieve armour performance exceeding that of the current light combat vehicles and main battle tanks, further advancements in armour materials, systems, and survivability technologies are required for new vehicular systems that weigh significantly less than the present combat platforms. Various approaches and advancements in the metallic and composite armour materials, ERA and NERA systems to improve the survivability of armoured vehicles in the futuristic multi-spectral battlefield scenarios are described

Assignment of NMR resonances of protons covalently bound to photochemically active cofactors in photosynthetic reaction centers by 13C–1H photo-CIDNP MAS-J-HMQC experiment

Solid state NMR/Biophysical Organic Chemistr

3C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center

C labeled RCs from the purple bacteria of Rhodobacter sphaeroides. We observed response from the protons belonging to the photochemically active cofactors in their native protein environment. Such an approach is a potential heteronuclear spin-torch experiment which could be complementary to the classical heteronuclear correlation (HETCOR) experiments for mapping proton chemical shifts of photosynthetic cofactors and to understand the role of the proton pool around the electron donors in the electron transfer process occurring during photosynthesis.Solid state NMR/Biophysical Organic Chemistr

Signal enhancement in the triple-quantum magic-angle spinning NMR of spins-3/2 in solids: the FAM-RIACT-FAM sequence

We achieve a significant signal enhancement for the triple-quantum magic-angle spinning NMR of a spin-3/2 system, by using an amplitude-modulated radiofrequency field, followed by a selective 90° pulse and a phase-shifted strong rf field, for the triple-quantum excitation, and an amplitude-modulated radiofrequency field for the conversion of triple-quantum coherence to observable single-quantum coherence. The experiment is demonstrated on the Rb-87 NMR of polycrystalline rubidium nitrate