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An electron pushing group has been introduced to a Schiff-base compound, 2-((2-(quinolin-2-yl)hydrazono)methyl)phenol (HQP) to get another Schiff-base molecule, namely, 4-methyl-2-((2-(quinolin-2-yl)hydrazono)methyl)phenol (HMQP), to modulate the Zn2+ sensing properties of the probe. HQP and HMQP have been synthesized by Schiff-base condensation between 2-hydrazinylquinoline and the respective aldehyde in 1:1 ratio and characterized by standard methods. Both the compounds show their Zn2+ sensing ability but to different extents. The fluorescence intensity of HQP at ~490 nm (λex = 410 nm) increases by about 4.5 folds in the presence of one equivalent of Zn2+ ion. However, the fluorescence intensity is enhanced by around 30 folds in the presence of one equivalent of Zn2+ in case of HMQP. The fluorescence peak of HMQP at 502 nm (λex = 420 nm) is shifted to 515 nm in the presence of Zn2+ whereas same type of shifting for HQP is found to be negligible. Some theoretical calculations have been performed to look into the spectral transitions of HMQP. Fluorescence intensity enhancement is explained by PET mechanism. Limit of detection (LOD) value for HMQP has been determined to be 220.6 nM, showing its good sensitivity towards zinc. The color change of HMQP under visible light is not conclusive in the presence of different metal ions, but only Zn2+ can induce green coloration to HMQP solution under UV light, thus indicating the possibility of naked eye detection by the analyte. HMQP with one equivalent of Zn2+ displays high fluorescence intensity in the pH range of 7.0–9.0 indicating its suitability towards biological applications. The probe has been utilized to live cell imaging studies using C6 cells.

A new lysosome-targetable fluorescence sensor, Lyso-HGP, was designed and synthesized based on 4-methyl-2,6-diformylphenol as a fluorophore. Lyso-HGP displays highly sensitive fluorescent detection of Hg2+ in HEPES buffer solution (10 mM, DMSO 1%) of pH 7.0 at 37 °C due to the formation of highly fluorescent formyl-functionalized derivative Lyso-HGP-CHO. The sensor triggered a "turn-on" fluorescence response to Hg2+ with a simultaneous increase of fluorescence intensity by 180-fold just after 10 min. The response is very selective over a variety of biologically relevant cations, anions, molecules, and competitive toxic heavy metal cations. The limit of detection (LOD) was calculated as low as 6.82 nM. So, it can be utilized to detect this toxic heavy metal in biology and environmental samples in an aqueous buffer medium. Also, the sensor is able to monitor the subcellular distribution of Hg2+ specifically localized in the lysosome's compartment in the MCF7 human breast cancer cell line by fluorescence microscopy.

A rhodamine based chemosensor, 3-(((2-(3′,6′-bis(ethylamino)-2′,7′-dimethyl-3-oxospiro[isoindoline-1,9′-xanthen]-2-yl)ethyl)imino)methyl)-2-hydroxy-5-methylbenzaldehyde (HL-CHO), has been developed for the detection of Al3+, Cr3+ and Fe3+ ions. The absorbance of HL-CHO at 528 nm increases significantly in HEPES buffer in methanol : water (9 : 1, v/v) (pH 7.4) in the presence of Al3+, Cr3+ and Fe3+ ions with the alteration of solution color from colorless to pink. The fluorescence intensity of the probe at 550 nm enhances by 1465, 588 and 800 fold in the presence of Al3+, Cr3+ and Fe3+ ions, respectively. To the best of our knowledge, this huge increase in fluorescence intensity with Al3+ and Cr3+ has not been observed for other rhodamine based chemosensing systems. The weak fluorescence and no coloration of the probe are due to the existence of a spirolactam ring. The trivalent cations induce the opening of the spirolactam ring and consequently change the color and the fluorescence intensity followed by the 1 : 1 complex formation with HL-CHO which are evident from Job's analysis, ESI mass spectral analysis and elemental analysis. The quantum yield and lifetime of HL-CHO have increased considerably in the presence of the trivalent cations. The high sensitivity of the probe towards all the cations is evident from the nM order of LOD values. This has been used in living cell imaging studies with the human neuroblastoma SH-SY5Y cell line. Having appended –CHO groups for Schiff-base condensation with other amines, HL-CHO could be a potential precursor for future chemosensors.

A naphthalimide-based fluorescence chemosensor, COFP, was designed and synthesized for the detection of carbon monoxide (CO) in HEPES buffer (pH 7.4, 37 °C). The detection process is highly selective towards CO, over a variety of relevant reactive oxygen, nitrogen, and sulfur species. Also, the fluorescence response is not hampered in the presence of biologically relevant metal ions and/or species. The detection method was achieved through the transformation of the nitro group of COFP to an amino functionalized derivative in the presence of CO without using any heavy metals e.g. Pd, Rh, Ru etc. The chemosensor prompted a ‘turn-on’ fluorescence response to CO with a simultaneous increase of the fluorescence intensity by more than 33 times. The LOD (limit of detection) was calculated to be as low as 123 nM using the 3σ method. Moreover, the chemosensor is capable of monitoring the changes in intracellular CO in the C6 glioma cell line.

A rhodamine based chemosensor, 3-(((2-(3',6'-bis(ethylamino)-2',7'-dimethyl-3-oxospiro[isoindoline-1,9'-xanthen]-2-yl)ethyl)imino)methyl)-2-hydroxy-5-methylbenzaldehyde (HL-CHO), has been developed for the detection of Al3+, Cr3+ and Fe3+ ions. The absorbance of HL-CHO at 528 nm increases significantly in HEPES buffer in methanol : water (9 : 1, v/v) (pH 7.4) in the presence of Al3+, Cr3+ and Fe3+ ions with the alteration of solution color from colorless to pink. The fluorescence intensity of the probe at 550 nm enhances by 1465, 588 and 800 fold in the presence of Al3+, Cr3+ and Fe3+ ions, respectively. To the best of our knowledge, this huge increase in fluorescence intensity with Al3+ and Cr3+ has not been observed for other rhodamine based chemosensing systems. The weak fluorescence and no coloration of the probe are due to the existence of a spirolactam ring. The trivalent cations induce the opening of the spirolactam ring and consequently change the color and the fluorescence intensity followed by the 1 : 1 complex formation with HL-CHO which are evident from Job's analysis, ESI mass spectral analysis and elemental analysis. The quantum yield and lifetime of HL-CHO have increased considerably in the presence of the trivalent cations. The high sensitivity of the probe towards all the cations is evident from the nM order of LOD values. This has been used in living cell imaging studies with the human neuroblastoma SH-SY5Y cell line. Having appended -CHO groups for Schiff-base condensation with other amines, HL-CHO could be a potential precursor for future chemosensors.

A new lysosome-targetable fluorescence sensor, Lyso-HGP, was designed and synthesized based on 4-methyl-2,6-diformylphenol as a fluorophore. Lyso-HGP displays highly sensitive fluorescent detection of Hg

The phosphorus (P) pollution and eutrophication in the aquatic environment are common and cause immensely adverse environmental health problems. In order to control the P pollution, the present study attempted to assess the phosphate-P removal capacity (PRC) of laterite soil (LS) and its application potentials in practical field. The physico-chemical characteristics of LS were analyzed using scanning electron microscopy coupled energy dispersive techniques, BET study and zeta potential. The PRC of LS was characterized by optimizing the sorption influencing parameters – contact time, solution pH, dosage of LS and concentration of phosphate-P as well as analyzing sorption isotherm and kinetics; and application potential of LS was evaluated by analyzing PRC in natural wastewater and by examining plant (Chick pea; Cicer arietinum) growth promoting properties of spent LS as phosphate fertilizer. The chemical characteristics revealed that LS is prevalently constituted by oxygen (48.52%), silicon (39.36%) and iron (10.57%) and aluminium (1.55%) and showed higher pore volume (1.678 cc/g), surface area (20.29 m2/g), particle density (2.25 g/cm3) and bulk density (1.94 g/cm3). LS demonstrated that contact time 390 min, pH 2.5, dosage 2.4 g/L and initial concentration 2 mg/L were optimum for highest phosphate-P sorption. Sorption data was well fitted by the Langmuir isotherm model and pseudo second order kinetic model. The phosphate-P sorption mechanism of LS is supposed to be governed by high porosity, surface area and specific chemical properties. LS showed excellent phosphate-P sorption (384.61 mg/g) and potential wastewater treatment properties. Phosphorous loaded spent LS also showed higher growth of Cicer arietinum (length of shoot, 38.21% and leaf number, 52.63%) than control. Therefore, the LS could ecofriendly be used as a low-cost sorbent for treating the polluted water and spent LS might be employed as a potentially fertile soil bed in yielding high amount of crop.

We report here 2-((2-morpholinoethylimino)methyl)-4-bromophenol (Hmmbp) as a dual chemosensor for the detection of Zn2+ and H2AsO4− ions in 10 mM HEPES buffer in water: methanol (9: 1, v/v) (pH = 7.4). It has been synthesized by the condensation between 5-bromo-2-hydroxybenzaldehyde and 2-morpholinoethanamine and characterized by different methods. Its fluorescence intensity at 458 nm increases by 32-fold in the presence of one eqv. of Zn2+ (λex:378 nm). Fluorescence enhancement occurs via PET and CHEF mechanism. Other cations cannot induce any considerable change in fluorescence properties of the probe. LOD value for Zn2+ has been determined to be 4.41 × 10−7 M. On the other hand, fluorescence intensity of Hmmbp enhances at 503 nm with one eqv. of H2AsO4− ion (λex:414 nm). In case of anion sensing, restriction of C N isomerization due to hydrogen bonding and ICT mechanism are responsible for the changes of fluorescence of Hmmbp. Detection limit for H2AsO4− has been found to be 3.22 × 10−7 M. The chemosensor is selective for arsenate ion over several common anions. It forms 1:1 complex with both Zn2+ and H2AsO4−.The probe has been utilized to image both the species using C6 rat brain glioma cells.

Although a variety of fluorescence based chemosensors have been utilized for selective detection of Zn2+, pyridoxal containing simple Schiff bases still remained less explored. Here, we combine pyridoxal hydrochloride and 1,2-diaminocyclohexane to generate a new sensor molecule, H4PydChda [5-Hydroxymethyl-4-({2-[5-hydroxymethyl-2-methylpyridin-3-hydroxy-4-ylethylene)-amino]-cyclohexylimino}-methyl-2-methylpyridin-3-ol]. Chemosensor H4PydChda exhibits selective turn-on type response in presence of Zn2+ in ethanol-water mixture at physiological pH. Appreciable fluorescence enhancement occurs upon addition of Zn2+ to H4PydChda as a result of inhibited C N isomerisation and excited state intramolecular proton transfer (ESIPT) leading to efficient chelation enhanced fluorescence (CHEF). The relevant properties, including reversibility, life time measurements and detection limit have been determined for the sensor system. The experimental and theoretical supports in terms of 1H and 13C NMR spectroscopy and DFT/TDDFT study are provided to establish the binding mode of H4PydChda to Zn2+. H4PydChda was employed as a sensor for detection of Zn2+ in Human gastric adenocarcinoma (AGS) cells. Moreover, the resulting probe-Zn2+complex shows convincing phosphatase activity (kcat = 21.59 s−1), opening a promising avenue for further research.

A new Schiff base ligand, 1-[(2-pyridin-2-yl-ethylimino)-methyl]-naphthalen-2-ol, (HPEMN) has been synthesized equipped with naphthalene and pyridine backbone, to study the interplay of various non-covalent interactions. Experiments have been carried out to investigate the outcome of combinations of HPEMN and ZnCl2 (1), ZnBr2 (2), ZnI2 (3), Zn(NO3)2·6H2O (4), Co(ClO4)2·6H2O (5), Cu(ClO4)2·6H2O (6) and VO(acac)2 (7). The prevalent non-covalent interactions described here include naphthalene–naphthalene (for 1, 2, 3 and 5) and pyridine–pyridine π–π stacking (for 4) interactions, nitrate anion⋯π interaction (for 4) and hydrogen bonding (for 6). HPEMN is able to sense Zn(II) selectively and this phenomenon was further demonstrated by the results of fluorescence studies in H2O/acetonitrile (8:2, v/v) HEPES buffer (pH = 7.4) solution and human lung cancer cell lines.

Proper fusion of fluorescence mechanisms in a single fluorophore unit is highly desirable to obtain better sensitivity, as well as selectivity towards a particular metal ion. In this regard, a Zn2+ chemosensor exhibiting strong fluorescence through synergistic CHEF-PET-ESIPT fluorescence mechanism has not received substantial deployment. This type of chemosensor provides an ample avenue to detect metal ions with a large stokes shift and are useful in living cell imaging study. Herein, we report an unparalleled Zn2+ chemosensor (L) based on these three types of fluorescence mechanisms by condensing 2,6-diformyl-4-methylphenol and 2-hydrazinyl-4,6-dimethylpyrimidine. All the three types of mechanism were experimentally verified by UV-Vis, fluorescence and time resolved photoluminescence (TRPL) spectroscopic evaluation. The sensor L and Zn2+ formed a 1 : 1 ratio complex demonstrating a high binding constant value (Ka = 4.812 × 105 M−1) and L showed clear discrimination from the Cd2+ ion. The limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 9.727 × 10−7 (M) and 3.24 × 10−6 (M), respectively. We have also shown that cell imaging can be performed using L without many cytotoxicity concerns.

2-Formyl-4-methyl-6-(2-benzoimidazolyliminomethyl)phenol (HL1) has been synthesized via Schiff-base condensation between 4-methyl-2,6-diformylphenol and 2-aminobenzimidazole in a 1:1 ratio in acetonitrile and characterized using elemental analysis and different spectroscopic methods. HL1 has been found to be a selective fluorescence sensor for Zn2+ ions. The emission intensity of HL1 at 528 nm in 10 mM HEPES buffer in water:methanol (1:9, v/v) (pH = 7.2) increases in the presence of Zn2+ when it is excited at 445 nm. Other metal ions can induce a slight increment or lowering of emission intensity. The spectral properties of HL1 and 2-formyl-4-methyl-6-(2-benzoimidazolylmethyliminomethyl)phenol (HL2) have been compared. It has been found that the presence of the methylene group in HL2 can have a significant effect on the absorption and fluorescence peak positions of the Schiff-base molecule and its zinc complex. Some theoretical calculations have been done to get a better view into the different spectral transitions. HL1 and HL2 have been found to be highly sensitive towards the detection of Zn2+ ions with very low LOD values. Excitation in the visible region and the effect of pH on the emission intensity of HL1 encourage us to carry out biological studies. HL1 has been used for human lung cancer cell (A549) imaging without cytotoxicity.

A pyridoxal-based fluorescent probe HL was synthesized for the detection of Cu(2+) in methanol with moderate selectivity. Upon addition of Cu(2+), to the solution of the probe in methanol exhibited a remarkable change in emission at 500 nm. With the limit of detection of 10 μM, the probe could well meet the recommended (less than 32 μM in drinking water) of the World Health Organization (WHO). The intracellular Cu(2+) imaging behaviour of HL was carried out on HeLa cells.

An 8-aminoquinoline based fluorescent Zn2+ sensor, 2-methoxy-6-((quinolin-8-ylimino)methyl)phenol (HL), was synthesized. It has been found to display quick responses through fluorogenic properties on selective 2:1 binding to Zn2+, as delineated by absorption and fluorescence titrations as well as by Job’s method and X-ray crystallography studies. This probe features visible light excitation (461 nm) and emission (594 nm) profiles, excellent selectivity responses for Zn2+ over other competing biological metal ions with high binding constant and about 17-fold enhancement in fluorescence quantum yield (Φ) upon half equivalent of Zn2+ binding under physiological pH window. The low detection limit in micromolar range (1.3 × 10−7 M) for Zn2+, makes HL a suitable candidate for the development of a potential probe. It also exhibits cell permeability and intracellular Zn2+ sensing in HeLa cells from human cervical cancer cell and rat hippocampal slices.

Healthy soils are of the utmost importance to society for the variety of ecosystem services they provide in both terrestrial and aquatic systems. Within aquatic systems, soils play an active role in carbon cycling and interactions between soils and water, and additional components of aquatic ecosystems can control the balance of carbon, whether the system becomes a net carbon source or sink. Understanding the interactions between soils and overlying water is crucial to developing adaptive strategies to mitigate climate change. An enhanced, holistic understanding of primary ecosystem drivers in mixed aquatic and soil systems is paramount for guiding their future construction and management to maximize their beneficial use while minimizing negative environmental impacts. Aeration and water circulation devices can be used to improve dissolved oxygen content of the wastewater pond system. Raking may be practiced to improve the ecological conditions of pond soils for encouraging healthy conditions and animal associations of the pond bottom particularly in wastewater-fed systems. The present chapter provides a review of different aspects of soil-water interactions and strategies to maintain ecosystem health for sustainable development.

This paper describes the activity of a Schiff base ligand, derived from pyridoxal, as a promising fluorescence probe for biologically important Zn(II) ion sensing. A physiologically compatible pyridoxal based chemosensor PydDmen was synthesized and evaluated for its fluorescent response towards metal ions. Chemosensor PydDmen exhibits a selective turn-on type response in the presence of Zn2+ in ethanol–water mixture. The addition of EDTA quenches the fluorescence of receptor PydDmen-Zn2+, making the chemosensor PydDmen reversible. The response is specific for Zn(II) ions, and remains almost unaffected by the presence of alkali and alkaline earth metals but is suppressed to varying degrees by transition metal ions. The selectivity mechanism of PydDmen for Zn2+ is the combined effects of proton transfer between the prevailing tautomeric forms, CN isomerization and CHEF. The DFT optimized structure of the complex is compatible with elemental analysis, mass spectrometry, FT-IR, electronic and NMR spectra. The experimental and theoretical support in terms of NMR spectroscopy and DFT are provided to establish the existence of Zn2+ induced transformation of PydDmen to a 3-pyridone tautomeric form.

A coumarin-based fluorogenic probe, PCO-1, senses carbon monoxide (CO) selectively in HEPES buffer at pH 8.0 through the intramolecular cyclization-elimination pathway based on Pd(0) mediated reaction. The probe exhibits a 'turn-on' response of CO over a variety of relevant reactive oxygen, nitrogen and sulfur species.

The well known rhodamine framework offers an ideal model for the development of fluorescence enhanced chemosensors. Herein, a novel and simple molecule chemosensor, (E)-2-((benzo[d][1,3]dioxol-4-ylmethylene)amino)-3′,6′-bis(diethylamino)spiro[isoindoline-1,9′-xanthen]-3-one ( L ), has been designed by combining a rhodamine B hydrazide and a benzo[d][1,3]dioxole-4-carbaldehyde in a single molecule to prove the selectivity and sensitivity for Al 3+ and Cr 3+ in a dual-channel mode (fluorescence emission and UV–Vis). The signal transduction occurred by the increase of conjugation in the ring-open form than in the ring-closed form. Furthermore, the chemosensor L could also be used as an imaging probe without cytotoxicity for uptake and detection of Al 3+ ion in HeLa cells.

Triazole motif linked rhodamine derivatives 1 and 2 were synthesized. Chemosensor 1 recognizes both Hg2+ and Pb2+ ions in CH3CN–water (4/1, v/v; 10 μM tris HCl buffer, pH 7.0) both colorimetrically and fluorometrically. In addition, chemosensor 1 is cell permeable and detects intercellular Hg2+ and Pb2+ ions. The aqueous phase recognition of these ions was also studied with a resin bound sensor 2 which exhibits more sensitivity and selectivity towards Hg2+ over Pb2+ ion.

A new water-soluble rhodamine-based Al3+ ion-selective probe (L1) was synthesised and characterized by physico-chemico and spectroscopic tools. In the presence of a large excess of other competing ions, L1 specifically binds Al3+ ions with a concurrent visually observable change from colorless to pink in electronic spectral behavior, making it possible to detect the presence of Al3+ ions with the naked eye. The addition of Al3+ ions to a solution of L1 in HEPES buffer (1 mM, pH 7.4, 2% EtOH) at 25 °C, results in a decrease in the weak fluorescence intensity at λem = 470 nm, while a new peak (at λem = 588 nm) increases gradually through a fluorescence resonance energy transfer process. This ratiometric enhancement helps to detect Al3+ ions at a very low concentration of 33 nM. The detection limit of L1 for Al3+ ions was estimated to be 6.19 × 10−9 M using the 3σ method. This probe is also useful for imaging Al3+ ions in HeLa cells.

A newly designed organic moiety, 5H-5,7a,12-triaza-dibenzo[a,e]azulen-6-one (L) containing a seven membered ring behaves as a hydrogen sulphate ion selective ratiometric chemosensor. The formulation and detailed structural characterisation of L have been established using physico-chemical, spectroscopic tools and single crystal X-ray diffraction study. On additions of hydrogen sulphate ions to the solution of L in HEPES buffer (1 mM; water : ethanol (v/v), 98 : 2) at 25 °C at biological pH, a new fluorescence peak generated at 483 nm was increased with concomitant decrease of the weak fluorescence of L at 430 nm through an isoemissive point at 449 nm due to the selective binding of HSO4− ions with L in a 1 : 1 ratio with a binding constant (K) of 4.13 × 106 M−1, and detects HSO4− ions as low as 5.5 × 10−7 M. The ratiometric enhancement of the fluorescence is based on intermolecular hydrogen bonding assisted chelation enhanced fluorescence (CHEF) process which has been evidenced by 1HNMR titration and supported by theoretical (DFT) calculations. The probe (L) having no cytotoxic effect is also useful for the detection of intracellular HSO4− ion concentrations under a fluorescence microscope.

A new chelating ligand [4-methyl-2,6-bis-(pyridin-2-yl-hydrazonomethyl)-phenol] (1) was prepared by the condensation of 2-hydrazinylpyridine with 2,6-diformyl-p-cresol. Compound 1 exhibits weak fluorescence due to intramolecular photoinduced electron transfer (PET). The sensor (1) demonstrates Zn(2+)-specific emission enhancement due to the “PET off” process through a 1:1 binding mode with the metal ion. The fluorescence quantum yield of chemosensor 1 is only 0.020, and it increases more than 14-fold (0.280) in the presence of one equivalent of the zinc ion. Interestingly, the introduction of other metal ions causes the fluorescence intensity to remain either unchanged or weakened except for Cd(2+). The new sensor showed ‘naked-eye’ detection of Zn(2+) ions: a color change of the solution from colorless to yellow. Ratiometric displacement of Cd(2+) ions from the complex by Zn(2+) ions supports the formation of a more stable sensor–Zn(2+) complex over the sensor–Cd(2+) complex. The experimental findings have been correlated with theoretical results using the B3LYP functional and 6-31G (d, p), LANL2DZ basis set for Cd(2+) (2) and Zn(2+) (3) complexes, respectively, by the Density Functional Theory (DFT) method. Moreover, the ability of probe 1 to sense Zn(2+) within human melanoma cancer cells has been explored, and the Zn(2+)-probing process in living cells was found to be reversible with zinc chelator solution of N,N,N,N-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) or EDTA.

Co66Fe2Si13B15Cr4 based amorphous microwire was developed at the laboratory using in-water quenching apparatus. The field sensitivity of the wire was enhanced when coated with ferrofluids. The presence of coating also decreased the frequency of the magnetising field 5MHz to 1MHz at which the maximum GMI ratio observed.

We report, herein, the development of an easily synthesizable novel dansyl-based turn-on NO sensor L2. The UV-Vis titration data of L2 with Cu(2+) display a gradual increase in absorbance at 418 nm with [Cu(2+)], which were analyzed by using a non-linear least-squares computer-fit program yielding K = (1.16 ± 0.36) × 10(6) M(-1) and n = (1.28 ± 0.03) indicating a 1 : 1 complexation. The ground state geometries of L2 as well as its complex [Cu(L2)Cl](+) (1) were optimized by DFT calculations which showed that in complex 1 the central metal ion is in distorted tetrahedral geometry with bond distances very close to those found in analogous Cu(2+) complexes. The fluorescence of L2 was dramatically quenched (∼60-fold) through complexation with paramagnetic Cu(2+) to form [Cu(L2)Cl](+) in MeCN-H2O (9 : 1, v/v) at pH 7.2 in HEPES buffer, which on further treatment with Angeli's salt (Na2N2O3) restores its fluorescence property by ∼15-fold due to the reduction of Cu(2+) to Cu(+) by NO generated in solution from Na2N2O3. The lifetime measurements displayed a substantial decrease in the lifetime of free ligand L2 (τ0 = 12 ns) on complexation with Cu(2+) (τ0 = 2.1 ns). The detection limit of NO calculated by the 3σ method gives a value of 1.6 nM. The NO induced fluorescence enhancement of [Cu(II)(L2)Cl](+) was due to the reduction of [Cu(II)(L2)Cl](+) (1) to [Cu(I)(L2)](+) (2) and is supported by the disappearance of the d-d transition band at 850 nm as well as the X-band EPR signal of 1. The selective "turn on" fluorogenic behavior of L2 was examined on HeLa cells of human cervical cancer origin by fluorescence microscopy which showed very intense intracellular fluorescence that was strongly suppressed by the addition of Cu(2+) but it regains its fluorescence property on further incubation with Angeli's salt (Na2N2O3). The existence of [Cu(II)(L2)Cl](+) and [Cu(I)(L2)](+) in solution was confirmed by ESI-MS(+) (m/z) analysis. The effect of different biologically relevant cations and anions on the fluorescence property of L2 indicates that it was only the [Cu(II)(L2)Cl](+) which displayed high selectivity for NO, indicating its suitability for intracellular application without much worry about its cytotoxicity in a specified dose.

A new highly sensitive and selective Hg(II) probe, 2-(rhodamine-b-hydrazido)-N-(quinolin-8-yl)acetamide (L1) was developed and characterized. L1 specifically binds to Hg(II) in the presence of a large excess of other competing ions with visually observable changes in both electronic and fluorescence spectral behaviour to make possible the naked eye detection of Hg(II) at a very low level (up to 4.5 × 10−7 M) through a fluorescence resonance energy transfer (FRET) process in HEPES buffer (1 mM, pH 7.4; 2% EtOH) at 25 °C. The theoretical and experimental kinetic study also support the binding of Hg(II) ion to induce the opening of the spirolactam ring in L1 for enabling the FRET process. Further studies reveal that the selective dissociation of the L–Hg complex in the presence of sulphide anions to restore the native structure of L1 is also useful in the detection of sulfide anions with a detection limit of a submicromolar range in the same medium of HEPES buffer (1 mM, pH 7.4; 2% EtOH) at 25 °C. L1 could be employed as a FRET based time dependent reversible chemosensor for imaging Hg(II) in living cells and whole bodies, and also could be used as an imaging probe for the detection of sulfide anions in HeLa cells.

As early as 1868, the first man-entry brick sewer of Kolkata (then Calcutta) along Lenin Sarani (then Dharamtolla Street) was commissioned as a part of an organised effort to provide a comprehensive combined sanitation facility. Subsequently, the city saw its golden age of construction of large-size brick sewers in its core area. Gradual and continuous deterioration over almost 140 years of its service life had caused occasional blockage, collapses, heavy siltation and water logging, mostly inflicted by lack of adequate and timely maintenance. In 2008, the Kolkata Municipal Corporation embarked on a major undertaking of refurbishing this most ancient and critically important brick sewer by trenchless technology. Its entire length of 2·8 km was rehabilitated using glass-reinforced plastic liners. The total cost of the project was more than £8.5 million (as in 2010) and it took about 2 years to refurbish and recommission (in 2010) this sewer to service.

Chemical fusion of a naturally occurring pharmacophore (pterocarpan) with a fluorophore (acridone) by thermally induced cascade sigmatropic rearrangement leads to the formation of a structurally different class of DNA binding ligands. Competitive binding assay in the presence of a classical minor groove binder shows the possibility of DNA minor groove binding by the ligand 4a. High cell viability of the prepared molecular probes was of utility for nuclear staining as well as cell cycle analysis through fluorescence-activated cell sorting (FACS).

A new rhodamine-based dual signaling probe (L3) has been found to display quick responses through visible colorimetric changes as well as fluorogenic properties on selective 1:1 binding to Hg2+, as delineated by absorption and fluorescence titrations as well as by Job′s method and ESI-MS+ studies. The fluorescent probe L3 displays a 252-fold fluorescence enhancement on binding to Hg2+. A Benesi–Hilderband fit of the absorption titration data gives Kd = (32.01 ± 0.74) μM and a 1:1 binding stoichiometry. Owing to its solubility in mixed organic/aqueous solvents as well as its cell permeability, L3 could be used for in vitro/in vivo cell imaging of Hg2+ with no or negligible cytotoxicity. The detection limit of Hg2+ was calculated by the 3σ method to be 9.28 ng L–1. Moreover, the fluorescence of the L3–Hg2+ system was turned off and its red colour disappeared when KI was added. Thus, the “OFF–ON–OFF” fluorescence sensing behaviour of L3 observed in the presence of Hg2+ and I– may find applications in devices with logic gate functions.

Gravity concentration in a liquid fluidized bed floatex density separator (FDS) was investigated through high-speed videography and image analysis. Process performance in terms of yield and grade of the product for fine coal beneficiation in the FDS was established experimentally. The feed coal (−1.18 mm) with 36% ash was enriched to 24% ash at a mass yield of 65%. Coarsest underflow with a d50 of 700 μm was obtained at 5.8 kPa bed pressure, 120 kg/h feed rate, and 12 lpm teeter water flow. The lowest SG50 of 1.62 was obtained at 5.4 kPa, 15 lpm, and 80 kg/h. At 9 lpm water flow, steady state was achieved in 400 sec when the voidage and suspension density distributions became constant. From the suspension density distribution, the SG50, 1.69 under this set of conditions, was estimated with reasonable accuracy. Increase in teeter water was shown to increase the time required for attaining steady state. It was established that particle size distribution at the bottom of the bed in the column offers a good i...

We report a systematic study of the influence of wire length, L, dependence of giant magneto-impedance (GMI) sensitivity of Co66Fe2Cr4Si13B15 soft magnetic amorphous wire of diameter ~100 µm developed by in-water quenching technique. The magnetization behaviour (hysteresis loops) of the wire with different length (L = 1, 2, 3, 5, 8 and 10 cm) has been evaluated by fuxmetric induction method. It was observed that the behaviour of the hysteresis loops change drastically with the wire length, being attributed to the existence of a critical length, L C, found to be around 3 cm. GMI measurements have been taken using automated GMI measurement system and the GMI sensitivities in terms of intrinsic impedance sensitivity (S Ω/Am −1) and voltage sensitivity (S V/Am −1) of the wire have been evaluated under optimal bias field and excitation current. It was found that the maximum (S Ω/Am −1) max ≈ 0.63 Ω/kAm−1/cm and (S V/Am −1) max ≈ 3.10 V/kAm−1/cm were achieved at a critical length L C ~ 3 cm of the wire for an AC current of 5 mA and a frequency of 5 MHz. These findings provide crucial insights for optimization of the geometrical dimensions of magnetic sensing elements and important practical guidance for designing high sensitive GMI sensors. The relevant combinations of magnetic material parameters and operating conditions that optimize the sensitivity are highlighted.

[6]-Gingerol, a pharmacologically important bioactive component of ginger, has been reported to have anti-hyperglycemic, anti-cancer and anti-oxidative properties, but mechanisms through which these are achieved are largely unclear. The present study focuses on apoptosis and autophagy, two key events of anti-cancer activity, in HeLa cells treated with [6]-gingerol. The treated cells showed several morphological changes, including externalization of phosphatidyl serine, degradation of DNA and increase in TUNEL positivity. Furthermore, there was depolarization of mitochondrial membrane potential, providing evidence of mitochondria mediated apoptosis. The expression of caspase 3 and PARP was increased in cells exposed to [6]-gingerol. Circular dichroism study for testing drug-DNA interaction with both calf thymus and nuclear DNA as target revealed that the drug had potential to bind with the nuclear DNA and induce conformational changes of DNA. The over-expression of NFkβ, AKT and Bcl2 genes in cancer cells was down-regulated by [6]-gingerol treatment. On the other hand the expression levels of TNFα, Bax and cytochrome c were enhanced in [6]-gingerol treated cells. Thus, overall results suggest that [6]-gingerol has potential to bind with DNA and induce cell death by autophagy and caspase 3 mediated apoptosis.

A simple salicylaldimine-based receptor equipped with rhodamine moiety (L3) has been designed and synthesized for detection of Al3+ ions, which exhibits high sensitivity over other metal ions in aqueous buffer-methanol solution at physiological pH. It displays quick responses through visible colorimetric as well as fluorogenic changes on 1:1 binding to Al3+, as delineated by absorption and fluorescence titrations and also by Job’s method and ESI-MS+ studies. However, it exhibits calorimetric but not fluorometric responses towards Cu2+ and hence limits its colorimetric application towards the detection of Al3+ in the presence of Cu2+ ions. The properties of the probe like (i) solubility in aqueous buffer-methanol, (ii) cell-permeability and (iii) non-toxic nature towards cell may provide an opportunity for the in vitro/ in vivo bio study. The detection limit of Al3+ calculated by the 3σ method was found to be 24.8 pM. It is also found to be useful in the construction of logic gates; namely ‘OR’ gate (from absorption) and molecular ‘keypad lock’ (from emission) by the two chemical inputs (Al3+ and Cu2+) in the proper sequence of addition. The keypad lock operation is particularly important, as the output of the system depends not only on the proper combination but also on the order of input signals, creating the correct password that can be used to ‘‘open’’ this molecular keypad lock through strong fluorescence emission at 552 nm. Besides, “OFF–ON–OFF” fluorescence behavior observed in the presence of Al3+ and EDTA strengthens the potential applications of the L3–Al3+ system as a device with ‘INHIBIT’ logic gate functions. As a whole, its various logic gate properties may improve its impact for the development of new-generation ‘intelligence’ digital devices. To the best of our knowledge, this is the first report on the fluorescence emission of a rhodamine derivative induced by Al3+ binding with such multiple logic gate operations accompanied by its application to cell-biology.

Crude ethanolic extract ofThuja occidentalis(Fam: Cupressaceae) is used as homeopathic mother tincture (TOΦ) to treat various ailments, particularly moles and tumors, and also used in various other systems of traditional medicine. Anti-proliferative and apoptosis-inducing properties of TOΦ and the thujone-rich fraction (TRF) separated from it have been evaluated for their possible anti-cancer potentials in the malignant melanoma cell line A375. On initial trial byS-diphenyltetrazolium bromide assay, both TOΦ and TRF showed maximum cytotoxic effect on A375 cell line while the other three principal fractions separated by chromatography had negligible or no such effect, because of which only TRF was further characterized and subjected to certain other assays for determining its precise anti-proliferative and apoptotic potentials. TRF was reported to have a molecular formula of C10H16O with a molecular weight of 152. Exposure of TRF ofThuja occidentalisto A375 cellsin vitroshowed more cytotoxic, anti-proliferative and apoptotic effects as compared with TOΦ, but had minimal growth inhibitory responses when exposed to normal cells (peripheral blood mononuclear cell). Furthermore, both TOΦ and TRF also caused a significant decrease in cell viability, induced inter-nucleosomal DNA fragmentation, mitochondrial transmembrane potential collapse, increase in ROS generation, and release of cytochromecand caspase-3 activation, all of which are closely related to the induction of apoptosis in A375 cells. Thus, TRF showed and matched all the anti-cancer responses of TOΦ and could be the main bio-active fraction. The use of TOΦ in traditional medicines against tumors has, therefore, a scientific basis.

Polygala senega is extensively used in traditional systems of medicine against various lung diseases including cancer. In the present study we tested the anticancer potentials of ethanolic extract of roots of P. senega (generally used as a homeopathic drug) in a mammalian model, where mice, in vivo, were treated chronically with benzo[a] pyrene and in vitro where lung adenocarcinoma cell line (A549) were used. We deployed various parameters like cell viability assay, chromatin condensation studies with Hoechst 333258 staining, and maintained suitable controls. To understand the possible signal transduction pathways, expression of various signal proteins such as Aryl Hydrocarbon receptor (AhR), cytochrome P450 (CYP1A1), Bcl-2, proliferating cell nuclear antigen (PCNA), Bax and Caspase-3 was studied. Additionally, reverse transcriptase polymerase chain reaction analysis of AhR, p53, PCNA and β-actin (housekeeping) genes was made. Immunohistochemical localization of PCNA proteins was also conducted in vivo. Feeding of root extract of P. senega to mice (at the rate of 50 mg/kg and 100 mg/kg bw) chronically treated with the carcinogen (50 mg/kg bw dissolved in olive oil) showed positive modulation in expression of signal proteins. Upregulation of apoptotic signals such as p53, Caspase-3 and Bax, and downregulation of AhR, cytochrome P450 (CYP1A1), Bcl-2 and PCNA were observed. Addition of root extract of Polygala Senega (at doses of 50 μg and 100 μg) into culture medium containing A549 cells induced recovery of decreased cell viability and increased chromatin fragmentation (apoptosis). Therefore, results of both in vivo and in vitro studies scientifically validate its potential use as an anticancer agent, particularly against lung cancer, and provide important information potentially helpful in drug designing.

Scopoletin, an alkaloid separated from ethanolic extract of the medicinal plant, Gelsemium sempervirens (Fam: Loganiaceae) has been reported to have anti-cancer potentials. The synthetic coumarin (4-Methyl-7 hydroxy coumarin) derived from resorcinol and ethyl aceto-acetate in presence of concentrated sulphuric acid is structurally close to scopoletin, being a coumarin derivative. Whether this synthetic compound also has anti-cancer potentials has been evaluated in vivo on DMBA (7,12-Dimethylbenz[a]anthracene) induced skin cancer in mice by analyzing results of several cytogenetic endpoints, Comet assay, and fluorescence activated cell sorting (FACS). Further, expressions of signal proteins like Aryl hydrocarbon receptor , p53, PCNA, Akt, Bcl-2, Bcl-xL, Bad, Bax, NF-kappaB Apaf, IL-6, Cytochrome-c, Caspase-3 and Caspase-9 were studied by immunoblot analysis along with histology of skin and immuno-histochemical localization of Aryl hydrocarbon receptor and PCNA in DMBA treated mice vis-a-vis carcinogen treated synthetic coumarin fed mice. Feeding of this synthetic coumarin induced positive modulations in expression of all biomarkers in DMBA administered mice, giving clues on its possible signaling pathway(s) - primarily through down-regulation of Aryl hydrocarbon receptor and PCNA and up-regulation of apoptotic proteins like Bax, Bad, Cytochrome c, Apaf, Caspase-3 and Caspase-9, resulting in an appreciable reduction in growth of papilloma in mice. Therefore, this synthetic coumarin shows promise for use in cancer therapy, particularly in skin cancer.

The chemical structure of the main fluorescenting compound in the ethanolic extract (mother tincture) of the American yellow jasmine, Gelsemium sempervirens, was determined by employing 1H nuclear magnetic resonance (NMR), 13C NMR, mass spectroscopy, high-performance liquid chromatography (HPLC), correlation spectroscopy (COSY), and Fourier transform infrared (FTIR) spectroscopy analyses. Spectrofluorometric analysis has been made of the mother tincture and its agitated serial dilutions (up to 12th potency) prepared according to a homeopathic procedure in which serial, agitated dilutions were made separately in glass and polypropylene containers. The succussions were made by employing three different modes: hand jerk, sonication, and vortexing. The chemical formula of scopoletin, the main fluorescent compound, was determined to be C10H8O4 having a molecular weight of 192.17. Significant differences were noted between the remedies prepared in the two types of containers. Further, a comparison between any two methods of agitation revealed significant differences in fluorometric data of remedies at certain potency levels. The biological (anticancer) action of the crude extract, the alkaloid scopoletin, and 2C potency of Gelsemium sp were tested in vitro on the HeLa cell line through fluorescence microscopy, the 3(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, and fluorescent activated cell sorting (FACS). The role of nanoparticles presumably derived from the containers, their orientation, and their interaction with the starting substance during the dynamization process initiated by different modes of agitation could possibly be attributed to the differences noted in the fluorometric data of potencies prepared in the two types of containers and among the three different means of succussion tested.

Lipids, especially sphingolipids, are emerging as inducer of apoptosis in a wide range of immortal cells, potentiating their therapeutic application in cancer. In the present study, a sphingolipid rich lipid fraction (denoted here as ALL), isolated from an attenuated strain of Leishmania donovani promastigote, was tested for its tumoricidal activity taking melanoma, the dreaded form of skin cancer cells, as model. ALL was found to induce chromatin condensation, internucleosomal DNA fragmentation and phosphatidylserine externalization with enhanced cell population in sub-G1 region in both mouse and human melanoma systems, namely B16F10 and A375 respectively. These are the hallmarks of cells undergoing apoptosis. Further analysis demonstrated that ALL treated melanoma cells showed significant increase in ROS generation, mitochondrial membrane potential depolarization, release of cytochrome c, and caspase-3 activation, which are the events closely involved in apoptosis. These findings indicate that one or more bioactive sphingolipid(s)/ceramide(s) present in ALL could be the causative agent(s) for the induction of apoptosis in melanoma cells. Further studies are thus necessary to identify these specific bioactive sphingolipid(s)/ceramide(s) and to establish their mechanism of action, in order to explore their use as anticancer agents.

Oxalic acid is now considered as a useful chemical in various hydrometallurgical processes. For its massive applications in hydrometallurgy, cost-effective production of the acid is necessary. In this direction, fermentative production of the acid from glucose appears attractive. Aspergillus niger , the main oxalic acid producing organism, in general oxidizes glucose rapidly to gluconic acid, and conversion of this sugar to oxalic and citric acid is always sufficiently less. In this article, we have shown that immobilized mycelia (bioparticles) of A. niger NCIM 548 strain secreted more oxalic acid from glucose than the amounts produced from either sucrose, lactose or glucose under submerged condition. Germination of immobilized spores in polyurethane foam yielded bioparticles which produced more (average: 3-fold on 7th day and 3.7-fold on 9th day) oxalic acid from glucose compared to free mycelium cells, mainly during the 2nd and 6th cycle. Recycled bioparticles maintained average activity of acid production up to six cycles.

China clay is an important mineral, which is used in the manufacture of ceramics and refractory, as also in other industries. Mined China clay contains iron oxides and silicates as impurity; if present in excess of a threshold level, the impurities affect the commercial value of the products. Currently available processes for lowering the iron content in China clay to the desired level (

A diformyl-p-cresol (DFC)-8-aminoquinoline based dual signaling probe was found to exhibit colorimetric and fluorogenic properties on selective binding towards Mg(2+) and Zn(2+). Turn-on fluorescent enhancements (FE) as high as 40 fold and 53 fold in 9 : 1 MeCN/water (v/v) at pH 7.2 in HEPES buffer for Mg(2+) and Zn(2+), respectively, were observed. The binding constants determined from the fluorescence titration data are: K = (1.52 ± 0.21) × 10(5) M(-1) and (9.34 ± 4.0) × 10(3) M(-2) at n = 1 and 0.5, for Mg(2+) and Zn(2+), respectively. The L : M binding ratios were also determined by Job's method, which support the above findings. This is further substantiated by HRMS analysis. Due to solubility in mixed organo-aqueous solvents as well as cell permeability it could be used for the in vitro/in vivo cell imaging of Mg(2+) and Zn(2+) ions with no or negligible cytotoxicity. This probe could be made selective towards Mg(2+) over Zn(2+) in the presence of TPEN, both under intra- and extracellular conditions and is superior to other Mg(2+) probes which suffer from selectivity of Mg(2+) over Ca(2+) or Zn(2+). Furthermore the dissociation constant (Kd = 6.60 μM) of the Mg(2+)-() complex is far lower than the so far reported Mg(2+) probes which fall in the mM range.

Molecules containing acridone and pterocarpan structural subunits are synthesized and their capability of binding duplex DNA is demonstrated.

The effect of substituents on FRET in two newly designed rhodamine-based Hg(2+) ion selective chemosensors (L¹ and L²) has been explored by a systematic experimental and theoretical study. Comparison of these sensors in the analytical study and imaging of Hg(2+) ions in living cells has also been included.

A simple salicylaldimine-based receptor equipped with rhodamine moiety (L3) has been designed and synthesized for detection of Al3+ ions, which exhibits high sensitivity over other metal ions in aqueous buffer-methanol...

This paper aims at developing an embedded giant magnetoimpedance (GMI) sensing device using balanced modulator/demodulator topologies. Its prototype compact model which is suitable for in-situ applications is fabricated by integrating the probe assembly and the processing circuits. The device measures the phase shift which in turn calibrates the magnitude of the magnetic field. Balanced modulator/demodulator topologies are incorporated for phase shift measurement which not only enhances the sensitivity of the sensing device due to the improvement of the signal to noise ratio but also improves the repeatability and reproducibility of the sensing device. The characterization results and the performance evaluations are included to demonstrate the improved performance of the sensing device.

A new probe, 3-[(3-benzyloxypyridin-2-ylimino)methyl]-2-hydroxy-5-methylbenzaldehyde (1-H) behaves as a highly selective fluorescent pH sensor in a Britton-Robinson buffer at 25 °C. The pH titrations show a 250-fold increase in fluorescence intensity within the pH range of 4.2 to 8.3 with a pK(a) value of 6.63 which is valuable for studying many of the biological organelles.

A new 2,6-bis(5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazolin-6-yl)-4-methylphenol (1) serves as a highly selective and sensitive fluorescent probe for Zn(2+) in a HEPES buffer (50 mM, DMSO:water = 1:9 (v/v), pH = 7.2) at 25 °C. The increase in fluorescence in the presence of Zn(2+) is accounted for by the formation of dinuclear Zn(2+) complex [Zn(2)(C(35)H(25)N(6)O)(OH)(NO(3))(2)(H(2)O)] (2), characterized by X-ray crystallography. The fluorescence quantum yield of the chemosensor 1 is only 0.019, and it increases more than 12-fold (0.237) in the presence of 2 equiv of the zinc ion. Interestingly, the introduction of other metal ions causes the fluorescence intensity to be either unchanged or weakened. By incubation of cultured living cells (A375 and HT-29) with the chemosensor 1, intracellular Zn(2+) concentrations could be monitored through selective fluorescence chemosensing.

Crude ethanolic extract of the plant Lycopodium clavatum has long been used in complementary and alternative medicine for treating various liver ailments and Alzheimer's disease. It has also been claimed to have potential anti-cancer properties in vivo in mice chronically fed liver carcinogens, p-dimethylamino azobenzene (initiator) and phenobarbital (promoter). Incidentally, crude ethanolic extract of Lycopodium clavatum is a mixture of some 201 alkaloids. In order to ascertain if any major fraction can be attributed to have pronounced anti-cancer effect, we examined this major fraction by eluting the crude extract in petroleum ether:ethyl aetate (17:3 vol/vol;) solvent and tried to understand its underlying mechanism. Studies on morphological changes, cell viability and cytotoxicity by microscopy and FACS, Western blot and immunofluorescence of Bcl-2, Bax, cytochrome c, caspase-3 were conducted. Lycopodine was found to induce chromatin condensation, inter-nucleosomal DNA fragmentation and enhanced cell population in sub-G1 region along with increase in reactive oxygen species generation and mitochondrial membrane potential depolarization, release of cytochrome c and activation of caspase-3 which are the events closely involved in apoptosis. An overall analysis of results showed that Lycopodine considerably inhibited growth of HeLa cells which indicates its potential use in chemotherapy.