Ultrasensitive Organic Humidity Sensor with High Specificity for Healthcare Applications

Humidity sensors have gained immense importance as non‐invasive, wearable healthcare devices for personal care as well as disease diagnostics. However, non‐specificity, poor stability at extreme conditions, and low sensitivity of the humidity sensor inhibit its usage as a health monitoring device. In the present study, N?F containing organic molecule, Selectfluor^TM (F‐TEDA) based humidity sensors with ～1–2 mm long needle‐shaped crystals is fabricated on interdigitated electrodes resulting in excellent performance. The unidirectional growth of crystals led to the formation of a conduction pathway for water molecules across the crystal, which otherwise are non‐conducting. The as‐fabricated humidity sensor at an operational voltage of 0.8 V displays a sensitivity of six orders in magnitude, best reported so far. The sensor does not exhibit any response upon exposure to various volatile organic compounds and reactive gases, indicating remarkable specificity. The sensor is tolerant to high moisture of 95 % for prolonged hours followed by monitoring over several days and degrades to 50 % of its original sensitivity only after continuous exposure for several days. Electrochemical impedance spectroscopy (EIS) shows reversal from resistive to capacitive behavior with increasing humidity levels. The fabricated humidity sensor acts as a healthcare device for breath rate monitoring and touch‐free examination of skin moisture.     

Synthesis and Characterization of Two Discrete Ln10 Nanoscopic Ladder‐Type Cages: Magnetic Studies Reveal a Significant Cryogenic Magnetocaloric Effect and Slow Magnetic Relaxation

Two unique lanthanide‐based cages [Ln₁₀( L )₅(μ₂‐OH)₆(H₂O)₂₂](Cl)₄?7 H₂O ([Gd₁₀] and [Dy₁₀]) have been synthesized by using a hydrazone‐based ligand H₄ L (H₄ L =2,6‐bis[(3‐methoxysalicylidene)hydrazinecarbonyl]pyridine) and LnCl₃?x H₂O. Structural characterization of [Gd₁₀] reveals an aesthetically pleasing self‐assembly of five L ^4? and ten Gd³⁺ ions forming a 2×[1×5] rectangular array. The ladder‐shaped cage consists of three “rungs” and two “rails” that are occupied by five ligands. Six out of ten gadolinium centers act as rung locks. Further analysis revealed that three chloride ions are encapsulated inside each discrete [Gd₁₀] molecule through hydrogen bonding and other noncovalent interactions. Both the complexes ([Gd₁₀] and [Dy₁₀]) were characterized by powder X‐ray diffraction and thermogravimetric analysis, which shows that they are isostructural in nature. Magnetic investigations reveal that [Gd₁₀] is a good candidate for magnetic refrigeration with a significant entropy change (?ΔS_m) of 37.4 J kg^?1 K^?1 for an applied field of 7 T and at 3 K. Whereas [Dy₁₀] shows single‐molecule‐magnet‐like behavior.     

Microwave absorption studies of MgB2 superconductor

Microwave absorption studies have been carried out on MgB₂ superconductor using a standard X-band EPR spectrometer. The modulated low-field microwave absorption signals recorded for polycrystalline (grain size ∼ 10 μm) samples suggested the absence of weak-link character. The field dependent direct microwave absorption has been found to obey a ✓H dependence with two different slopes, which indicated a transition from strongly pinned lattice to flux flow regime.     

New modifications in 15 UD pelletron at nuclear science centre

The 15 UD pelletron at NSC has been operational and performed well during the last 11 years. There have been major modifications performed for upgradation of pelletron system over this period. Major upgradations which have been implemented are new resistor network system for voltage gradient, doublet to singlet unit conversion for accelerator units, turbopump based gas stripper system etc. In addition accelerator mass spectroscopy program has also been started. A new multi-cathode source, Wien filter etc. have been procured and will be added soon in the system. An overview of the most significant upgradations undertaken and other activities for the system are being reported in the present paper.     

Effect of substrate temperature on electrical and magnetic properties of epitaxial La1−x Pb x MnO3 films

Epitaxial La_1−x Pb _x MnO₃ (LPMO) thin films, grown on (100) SrTiO₃ substrates by laser ablation technique at different temperatures between 600 and 850°C, have been characterized for electrical and magnetic properties. The temperature dependence of resistivity showed that the metal-insulator transition temperature (T _MI) decreases with increasing substrate temperature, which has been attributed to decrease in Pb content in the filsm. The YBa₂Cu₃O _x /La_1−x MnO₃ heterostructures, exhibiting both superconductivity and ferromagnetism, have been fabricated.     

Regioselective Synthesis of Quinazolinone‐/Phenanthridine‐Fused Heteropolycycles by Pd‐Catalyzed Direct Intramolecular Aerobic Oxidative C−H Amination from Aromatic Strained Amides

A new route for the expedient synthesis of specific regioisomer of quinazolinone‐ and phenanthridine‐fused heterocycles through a palladium‐catalyzed regioselective intramolecular oxidative C?H amination from cyclic strained amides of aromatic amido–amidine systems (quinazolinones) has been developed. The amine functionalization of an aromatic C?H bond from a strained amide nitrogen involved in aromaticity has been a challenging work so far. The fusion of two heterocyclic cores, quinazolinone and phenanthridine, can occur in two different ways (linear and angular), but under the conditions reported here, only linear type isomer is exclusively produced. This approach provides a variety of substituted quinazolinone‐ and phenanthridine‐fused derivatives in moderate to excellent yields. Moreover, such fused molecules show excellent fluorescent properties and have great potential to be a new type of fluorophores for the use in medicinal and material science.     

Mass Spectrometry Based Mechanistic Insights into Formation of Tris Conjugates: Implications on Protein Biopharmaceutics

We present here extensive mass spectrometric studies on the formation of a Tris conjugate with a therapeutic monoclonal antibody. The results not only demonstrate the reactive nature of the Tris molecule but also the sequence and reaction conditions that trigger this reactivity. The results corroborate the fact that proteins are, in general, prone to conjugation and/or adduct formation reactions and any modification due to this essentially leads to formation of impurities in a protein sample. Further, the results demonstrate that the conjugation reaction happens via a succinimide intermediate and has sequence specificity. Additionally, the data presented in this study also shows that the Tris formation is produced in-solution and is not an in-source phenomenon. We believe that the facts given here will open further avenues on exploration of Tris as a conjugating agent as well as ensure that the use of Tris or any ionic buffer in the process of producing a biopharmaceutical drug is monitored closely for the presence of such conjugate formation.

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Graphical Abstract ?

     

Provably secure dynamic identity-based three-factor password authentication scheme using extended chaotic maps

With the aim of guaranteeing secure communication through public networks, three-factor password authentication (TF-PWA) scheme plays a key role in many internet applications. Since in TF-PWA scheme, the communicating entities can mutually authenticate each other and generate a shared session key, which will be used for secure exchange of messages in succeeding communication among them. As a result, the TF-PWA schemes gain enormous consideration in recent years. More recently, due to light-weight features of the extended chaotic map, it is also extensively applied in designing of public key encryption, key agreement, image encryption, S-box, hash function, digital signature, password authentication, etc. The aim of this paper was to design a dynamic identity-based three-factor password authentication scheme using extended chaotic map (ECM-TF-PWA) in the random oracle model. The proposed scheme is provably secure based on the intractability assumption of chaotic map-based Diffie–Hellman problem. The informal security analysis gives the evidence that our scheme protects all attacks and provides functionality attributes that are needed in a three-factor authentication system. Besides, the performance discussion shows that our scheme performs better than others in respect of computation and communication cost.     

Unusual spectral renormalization in hexaborides

Employing high resolution photoemission spectroscopy, we studied the evolution of the spectral features in rare earth hexaboride single crystals as a function of temperature and 4f binding energy, where the variation of the 4f binding energy is obtained by changing the rare earth element. High energy resolution helped to reveal the distinct features corresponding to the various photoemission final states. Experimental results of CeB(6), a dense Kondo system, exhibit the growth of the features near the Fermi level with the decrease in temperature relative to the uncompensated local moment contributions. The valence band spectra of the antiferromagnetic compounds, PrB(6) and NdB(6), exhibit multiple features-the 4f ionization peaks (poorly screened features) appear at higher binding energies and the features in the vicinity of the Fermi level possessing significant 4f character are due to the well-screened photoemission final states. These results indicate finite hybridization between the 4f and B 2s2p conduction electronic states. Interestingly, the well-screened features in PrB(6) and NdB(6) exhibit unusual enhancement in intensity at low temperature.