Butterflyene: an entry into an aesthetically pleasing carbocycle via a Diels-Alder reaction on a tetrasubstituted olefin.

An interesting molecular architecture, butterflyene, resembling the shape of a butterfly has been synthesized via a sequence of cyclocondensation, benzylic oxidation, McMurry coupling and Diels-Alder reaction (DAR), successively. The DAR of the tetrasubstituted double bond of a bicyclopentylidene moiety with various dienes has been performed to prepare the analogues of butterflyene. DFT calculations have also been used to analyze the structural optimization and reaction energies.

Multimodal imaging characteristics in eyes with vitreoretinal lymphoma treated with intravitreal rituximab.

PURPOSE: To characterize the imaging features in eyes with vitreoretinal lymphoma (VRL) using ultra-widefield fundus photography (UWF-FP), swept-source optical coherence tomography (SSOCT) and fundus autofluorescence (FAF) that are correlated to ongoing treatment with intravitreal Rituximab(IVR). METHODS: Retrospective observational imaging-based study of 15 treatment-naive eyes with VRL treated with IVR. All patients with primary VRL underwent vitreous biopsy using 23/25G microincision vitrectomy system for confirmation of diagnosis. All eyes received monthly IVR (1 mg/0.1 mL) injections till disease remission. Baseline clinical characteristics, treatment details, outcomes, and sequential imaging features on UWF-FP, FAF, and SSOCT were analyzed. OUTCOME MEASURES: Baseline features and changes in UWF-FP, FAF patterns, and SSOCT features in response to treatment RESULTS: Clinically, patients presented with sub-RPE deposits (n = 15), superficial retinal hemorrhages (n = 2), 'giant' RPE (retinal pigment epithelium) holes (n = 2), and anterior segment reaction (n = 1). Eyes were treated with mean 5.7 IVR injections (median: 5; range 1-13) over a mean 7.2 ± 4.9 months. During the course of treatment, two eyes developed superficial retinal hemorrhages with spontaneous resolution, 2 eyes developed CME, and 4 eyes developed characteristic 'leopard skin' pigmentation. Hyper-autofluorescence corresponding to areas of active lesions decreased with each treatment cycle and was finally replaced by hypo-autofluorescence. Serial OCTs showed regression of sub-RPE/subretinal deposits (n = 15), ellipsoid zone disruption (n = 9), and its resolution with treatment (n = 3), epiretinal membrane (ERM; n = 6), choroidal hyperreflective foci (HRF; n = 4), disorganization of retinal inner layers (DRIL; n = 3), RPE-rip (n = 2), cystoid macular edema (CME; n = 2), and hyperreflective lesions in the choroid (n = 1). Complete resolution was observed in all eyes with extensive hypo-AF. The central foveal thickness decreased from 237 ± 113 µ to 182 ± 114 µ (p = 0.1) and subfoveal choroidal thickness decreased from 258 ± 66 µ to 220 ± 64 µ (p = 0.12) at final follow-up. The mean baseline BCVA was logMAR 0.9 ± 0.9 that deteriorated to mean logMAR 1 ± 1 final visit (p = 0.7). The mean recurrence-free follow-up was 5.9 ± 5.1 months CONCLUSION: Multimodal imaging provides novel insights into features of VRL, a better understanding of regression patterns, and prognostication of outcomes when treated with intravitreal rituximab. Larger, multicentric studies with longer follow-up will help unravel imaging biomarkers to understand these aspects better.

Intravitreal rituximab monotherapy for management of eyes with vitreoretinal lymphoma: initial experience from India.

PURPOSE: To evaluate treatment outcomes and complications of intravitreal rituximab (IVR) monotherapy for eyes with vitreoretinal lymphoma (VRL). METHODS: Patients diagnosed with 'isolated primary VRL' or 'VRL with remission of systemic disease' and treated with IVR (1 mg/0.1 ml) between June 2014 and June 2019 were included in this retrospective, interventional case series. Injections were repeated at monthly intervals until complete resolution. All patients signed a written informed consent form. Institutional review board approval was obtained. RESULTS: Twelve eyes of 7 patients with VRL were treated with 77 IVR injections at mean 6.42 injections per eye (median = 5; range = 2-13) for complete resolution at mean 8.16 ± 4.62 months (median = 6.97 months; range = 1.97-14.33 months). Mean age at presentation was 53.3 years (median = 54 years; range = 34-74 years). Patients were co-managed with medical oncologist and periodically evaluated. Complications included anterior uveitis (n = 6), raised intraocular pressure (n = 3), posterior synechiae (n = 2), vitreous haemorrhage (n = 1), pre-retinal haemorrhage (n = 1), retinal detachment (n = 1), posterior subcapsular cataract (n = 2) and sectoral iris atrophy (n = 1). Recurrences were seen in 3 eyes (25%), which eventually achieved complete resolution with treatment. None of the patients had systemic involvement or death during follow-up. Mean follow-up was 18.73 ± 8.83 months (median = 21.60 months; range = 7.37-32.67 months). CONCLUSION: Intravitreal rituximab monotherapy is effective in management of vitreoretinal lymphoma in patients with isolated ocular disease.

Electrospun Nanofiber Mats as "Smart Surfaces" for Desorption Electrospray Ionization Mass Spectrometry (DESI MS)-Based Analysis and Imprint Imaging.

In this paper, desorption electrospray ionization mass spectrometry (DESI MS)-based molecular analysis and imprint imaging using electrospun nylon-6 nanofiber mats are demonstrated for various analytical contexts. Uniform mats of varying thicknesses composed of ∼200 nm diameter fibers were prepared using needleless electrospinning. Analytical applications requiring rapid understanding of the analytes in single drops, dyes, inks, and/or plant extracts incorporated directly into the nanofibers are discussed with illustrations. The possibility to imprint patterns made of printing inks, plant parts (such as petals, leaves, and slices of rhizomes), and fungal growth on fruits with their faithful reproductions on the nanofiber mats is illustrated with suitable examples. Metabolites were identified by tandem mass spectrometry data available in the literature and in databases. The results highlight the significance of electrospun nanofiber mats as smart surfaces to capture diverse classes of compounds for rapid detection or to imprint imaging under ambient conditions. Large surface area, appropriate chemical functionalities exposed, and easiness of desorption due to weaker interactions of the analyte species are the specific advantages of nanofibers for this application.

A panel study of the acute effects of personal exposure to household air pollution on ambulatory blood pressure in rural Indian women.

BACKGROUND: Almost half the world's population is exposed to household air pollution from biomass and coal combustion. The acute effects of household air pollution on the cardiovascular system are poorly characterized. We conducted a panel study of rural Indian women to assess whether personal exposures to black carbon during cooking were associated with acute changes in blood pressure. METHODS: We enrolled 45 women (ages 25-66 years) who cooked with biomass fuels. During cooking sessions in winter and summer, we simultaneously measured their personal real-time exposure to black carbon and conducted ambulatory blood pressure measurements every 10min. We recorded ambient temperature and participants' activities while cooking. We assessed body mass index, socioeconomic status, and salt intake. Multivariate mixed effects regression models with random intercepts were used to estimate the associations between blood pressure and black carbon exposure, e.g., average exposure in the minutes preceding blood pressure measurement, and average exposure over an entire cooking session. RESULTS: Women's geometric mean (GM) exposure to black carbon during cooking sessions was lower in winter (GM: 40µg/m(3); 95% CI: 30, 53) than in summer (GM: 56µg/m(3); 95% CI: 42, 76). Interquartile range increases in black carbon were associated with changes in systolic blood pressure from -0.4mm Hg (95% CI: -2.3, 1.5) to 1.9mm Hg (95% CI: -0.8, 4.7), with associations increasing in magnitude as black carbon values were assessed over greater time periods preceding blood pressure measurement. Interquartile range increases in black carbon were associated with small decreases in diastolic blood pressure from -0.9mm Hg (95% CI: -1.7, -0.1) to -0.4mm Hg (95% CI: -1.6, 0.8). Associations of a similar magnitude were estimated for cooking session-averaged values. CONCLUSIONS: We found some evidence of an association between exposure to black carbon and acute increases in systolic blood pressure in Indian women cooking with biomass fuels, which may have implications for the development of cardiovascular diseases.

Zero Volt Paper Spray Ionization and Its Mechanism.

The analytical performance and a suggested mechanism for zero volt paper spray using chromatography paper are presented. A spray is generated by the action of the pneumatic force of the mass spectrometer (MS) vacuum at the inlet. Positive and negative ion signals are observed, and comparisons are made with standard kV paper spray (PS) ionization and nanoelectrospray ionization (nESI). While the range of analytes to which zero volt PS is applicable is very similar to kV PS and nESI, differences in the mass spectra of mixtures are interpreted in terms of the more significant effects of analyte surface activity in the gentler zero volt experiment than in the other methods due to the significantly lower charge. The signal intensity of zero volt PS is also lower than in the other methods. A Monte Carlo simulation based on statistical fluctuation of positive and negative ions in solution has been implemented to explain the production of ions from initially uncharged droplets. Uncharged droplets first break up due to aerodynamics forces until they are in the 2-4 µm size range and then undergo Coulombic fission. A model involving statistical charge fluctuations in both phases predicts detection limits similar to those observed experimentally and explains the effects of binary mixture components on relative ionization efficiencies. The proposed mechanism may also play a role in ionization by other voltage-free methods.

Portal flow modulation in auxiliary partial orthotopic liver transplantation.

APOLT is a suitable technique of liver transplantation in patients with ALF and some types of MLD. Portal venous steal is a problem with this procedure that leads to graft dysfunction and failure. Modulation of the portal flow to the graft and native liver can help in preventing this problem. We discuss the pathophysiology of this complication, review available literature regarding its management, and describe our results using the technique of graded hemiportal banding to achieve adequate perfusion for the graft and native liver.

Steric considerations on improving the diastereomeric ratio of (+)- and (-)-neomenthyl phenyl sulfoxides using bulky-headed oxidant hexadecyltrimethylammonium periodate and assignment of their configuration.

The bulky-headed oxidant hexadecyltrimethylammonium periodate affords the diastereomeric pairs, (Ss)-(+)/(Rs)-(+) and (Ss)-(-)/(Rs)-(-)-neomenthyl phenyl sulfoxides in stereochemically pure states with improved diastereomeric excess (48% diastereomeric excess [de]) as compared to its nonbulky counterpart, sodium metaperiodate (28% de) from respective (+)/(-)-neomenthyl phenyl sulfides. Steric effects involving the head group volume of hexadecyltrimethylammonium periodate is found to play a role in improving the diastereomeric ratio of the products. The two diastereomers can be readily separated by column chromatography. Absolute configuration at the sulfur center in (+)-neomenthyl phenyl sulfoxide was determined by single-crystal X-ray crystallography and found to be Ss. Relative configurations of other sulfoxides were assigned based on the configuration of (+)-neomenthyl phenyl sulfoxide.

Graphene: a reusable substrate for unprecedented adsorption of pesticides.

Unprecedented adsorption of chlorpyrifos (CP), endosulfan (ES), and malathion (ML) onto graphene oxide (GO) and reduced graphene oxide (RGO) from water is reported. The observed adsorption capacities of CP, ES, and ML are as high as ~1200, 1100, and 800 mg g(-1) , respectively. Adsorption is found to be insensitive to pH or background ions. The adsorbent is reusable and can be applied in the field with suitable modifications. A first-principles pseudopotential-based density functional analysis of graphene-water-pesticide interactions showed that the adsorption is mediated through water, while direct interactions between graphene and the pesticides is rather weak or unlikely.

Ultrafast photoinduced enhancement of nonlinear optical response in 15-atom gold clusters on indium tin oxide conducting film.

We show that the third order optical nonlinearity of 15-atom gold clusters is significantly enhanced when in contact with indium tin oxide (ITO) conducting film. Open and close aperture z-scan experiments together with non-degenerate pump-probe differential transmission experiments were done using 80 fs laser pulses centered at 395 nm and 790 nm on gold clusters encased inside cyclodextrin cavities. We show that two photon absorption coefficient is enhanced by an order of magnitude as compared to that when the clusters are on pristine glass plate. The enhancement for the nonlinear optical refraction coefficient is ~3 times. The photo-induced excited state absorption using pump-probe experiments at pump wavelength of 395 nm and probe at 790 nm also show an enhancement by an order of magnitude. These results attributed to the excited state energy transfer in the coupled gold cluster-ITO system are different from the enhancement seen so far in charge donor-acceptor complexes and nanoparticle-conjugate polymer composites.

Facile and rapid synthesis of a dithiol-protected Ag7 quantum cluster for selective adsorption of cationic dyes.

We report a facile and rapid (less than 15 min) synthesis of atomically precise, dithiol-protected, silver quantum cluster, Ag7(DMSA)4 (DMSA: meso-2,3-dimercaptosuccinic acid), through a modified solid state route. The as-synthesized cluster exhibits molecular optical absorption features with a prominent λmax at ~500 nm. Composition of the cluster was confirmed using various spectroscopic and microscopic techniques such as electrospray ionization mass spectrometry (ESI MS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive analysis of X-rays (EDAX). Clusters supported on neutral alumina have been shown as better adsorbents for selective adsorption of cationic dyes (over anionic dyes) from water. This selectivity for cationic dyes was evaluated by zeta potential (ζ) measurements. The efficiency of clusters for removal of dyes is very high when compared to nanoparticles (NPs) protected with ligands (citrate and mercaptosuccinic acid (MSA)) possessing similar chemical structures as that of DMSA. The higher efficiency of clusters for the removal of dyes is attributed to their smaller size and large surface area compared to the NPs in addition to favorable electrostatic interactions between the clusters and cationic dyes. Adsorption of dyes (cationic and anionic) was enhanced when dye molecules contain hydrogen bond forming functional groups. Supported clusters have been reused up to five cycles without the loss of activity once the adsorbed dye is extracted using suitable solvents.

Embelin accelerates cutaneous wound healing in diabetic rats.

This study reports the effect of embelin (1) on cutaneous wound in streptozotocin (STZ)-induced diabetic rats. The effect was studied using excision, incision, and dead space models. In diabetic rats, topical application of embelin 5% (w/w) ointment showed a significant increase in wound contraction and better epithelialization, thereby facilitating the healing. Embelin was also active by the oral route (25 and 50 mg/kg) in the incision and dead space wound models. In incision wound model, wound granulation tissues were removed on 8th post-wounding day, and the hydroxyproline, hexosamine, total protein, and DNA contents were determined. In STZ diabetic rats, topical and oral applications of embelin showed an increase in hydroxyproline, hexosamine, total protein, and DNA contents. It also showed a significant increase in wound breaking strength. Embelin significantly increased granuloma tissue weight and breaking strength in dead space model. These results indicated that embelin accelerated wound healing in diabetic rat.

The superstable 25 kDa monolayer protected silver nanoparticle: measurements and interpretation as an icosahedral Ag152(SCH2CH2Ph)60 cluster.

A cluster obtained in high yield from the reduction of a silver-thiolate precursor, Ag-SCH(2)CH(2)Ph, exhibited a single sharp peak near 25 kDa in the matrix-assisted laser desorption mass spectrum (MALDI MS) and a well-defined metal core of ~2 nm measured with transmission electron microscopy (TEM). The cluster yields a single fraction in high-performance liquid chromatography (HPLC). Increased laser fluence fragments the cluster until a new peak near 19 kDa predominates, suggesting that the parent cluster-Ag(152)(SCH(2)CH(2)Ph)(60)-evolves into a stable inorganic core-Ag(152)S(60). Exploiting combined insights from investigations of clusters and surface science, a core-shell structure model was developed, with a 92-atom silver core having icosahedral-dodecahedral symmetry and an encapsulating protective shell containing 60 Ag atoms and 60 thiolates arranged in a network of six-membered rings resembling the geometry found in self-assembled monolayers on Ag(111). The structure is in agreement with small-angle X-ray scattering (SAXS) data. The protective layer encapsulating this silver cluster may be the smallest known three-dimensional self-assembled monolayer. First-principles electronic structure calculations show, for the geometry-optimized structure, the development of a ~0.4 eV energy gap between the highest-occupied and lowest-unoccupied states, originating from a superatom 90-electron shell-closure and conferring stability to the cluster. The optical absorption spectrum of the cluster resembles that of plasmonic silver nanoparticles with a broad single feature peaking at 460 nm, but the luminescence spectrum shows two maxima with one attributed to the ligated shell and the other to the core.

Understanding the degradation pathway of the pesticide, chlorpyrifos by noble metal nanoparticles.

Application of nanoparticles (NPs) in environmental remediation such as water purification requires a detailed understanding of the mechanistic aspects of the interaction between the species involved. Here, an attempt was made to understand the chemistry of noble metal nanoparticle-pesticide interaction, as these nanosystems are being used extensively for water purification. Our model pesticide, chlorpyrifos (CP), belonging to the organophosphorothioate group, is shown to decompose to 3,5,6-trichloro-2-pyridinol (TCP) and diethyl thiophosphate at room temperature over Ag and Au NPs, in supported and unsupported forms. The degradation products were characterized by absorption spectroscopy and electrospray ionization mass spectrometry (ESI MS). These were further confirmed by ESI tandem mass spectrometry. The interaction of CP with NP surfaces was investigated using transmission electron microscopy, energy dispersive analysis of X-rays, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). XPS reveals no change in the oxidation state of silver after the degradation of CP. It is proposed that the degradation of CP proceeds through the formation of AgNP-S surface complex, which is confirmed by Raman spectroscopy. In this complex, the P-O bond cleaves to yield a stable aromatic species, TCP. The rate of degradation of CP increases with increase of temperature and pH. Complete degradation of 10 mL of 2 ppm CP solution is achieved in 3 h using 100 mg of supported Ag@citrate NPs on neutral alumina at room temperature at a loading of ∼0.5 wt %. The effect of alumina and monolayer protection of NPs on the degradation of CP is also investigated. The rate of degradation of CP by Ag NPs is greater than that of Au NPs. The results have implications to the application of noble metal NPs for drinking water purification, as pesticide contamination is prevalent in many parts of the world. Study shows that supported Ag and Au NPs may be employed in sustainable environmental remediation, as they can be used at room temperature in aqueous solutions without the use of additional stimulus such as UV light.

Rapid identification of molecular changes in tulsi (Ocimum sanctum Linn) upon ageing using leaf spray ionization mass spectrometry.

Tulsi or Holy Basil (Ocimum sanctum Linn) is a medicinally important plant. Ursolic acid (UA) and oleanolic acid (OA) are among its major constituents which account for many medicinal activities of the plant. In the present work, we deployed a new ambient ionization method, leaf spray ionization, for rapid detection of UA, OA and their oxidation products from tulsi leaves. Tandem electrospray ionization mass spectrometry (ESI-MS) has been performed on tulsi leaf extracts in methanol to establish the identity of the compounds. We probed changes occurring in the relative amounts of the parent compounds (UA and OA) with their oxidized products and the latter show an increasing trend upon ageing. The findings are verified by ESI-MS analysis of tulsi leaf extracts, which shows the same trend proving the reliability of the leaf spray method.

Vaccine hesitancy towards COVID vaccine among unvaccinated frontline health care workers working in a designated COVID care center: A cross-sectional study.

Background: Frontline health care workers (FLHCW) like doctors and nurses are bound to treat COVID patients being themselves not immune to disease are at a greater risk of COVID infection than the general population. The study was started with objectives to find out the vaccine hesitancy towards the COVID vaccine and to find out the factors associated with vaccine hesitancy among FLHCW working in a designated COVID care center. Materials and Methods: The present study was a cross-sectional study carried out for a period of 6 months from Jan 2021 to June 2021 at a designated COVID care center. FLHCWs who were part of treating COVID patients were our study participants. Among them, FLHCWs who had not received even one dose of COVID vaccine (Covishield) were included in the study. FLHCWs who had been part of the COVID vaccine trial were excluded from the study. The sample size calculated based on a previous study found to be 240. The data collected were entered into a Microsoft office excel sheet, analyzed using SPSS v 22(IBM Corp). Descriptive statistics were applied, and parametric tests were used to compare among the groups with statistically significant P value lesser than 0.05. Results: A total of 121 (52.6%) of FLHCWs were aged more than 30 years, 118 (51.5%) were male participants, 100 (43.5%) were paramedics by occupation, 51 (22.1%) had contracted COVID infection, 202 (87.8%) had received information, education, and communication (IEC) regarding COVID vaccine. FLHCWs more than 30 years, male participants, currently not working in COVIDward, FLHCWs who had not received IEC about COVIDvaccination and paramedics had higher scores of Vaccine hesitancy, and the difference was statistically significant indicating vaccine hesitancy. Conclusion: Vaccine hesitancy remains a persistent global threat. Awareness campaigns can be tailored to specific locales to address identified concerns regarding vaccines.

Impact of ultraviolet-absorbing 2-hydroxy-4-quaternaryammoniumalkoxy benzophenone motif on photodegradation of disulfoton: a case study.

Pesticide deposits post-treatment and before diffusing inside the plants are exposed to sunlight. Many of them degrade into a variety of photoproducts that may be harmful to living beings through accidental ingestion. The addition of ultraviolet light absorbers to the pesticide formulations is an attractive strategy to prevent photodegradation of the pesticides. Water-soluble quaternary ammonium ultraviolet light absorbers (QAUVAs) were synthesized from 2,4-dihydroxy benzophenones (BP-1) and their structures were confirmed by 1H NMR, 13C NMR, UV, and FTIR. A cost-saving approach for the photoprotection of disulfoton insecticide using these QAUVAs is presented. All the four QAUVAs exhibit excellent UV screening effect. The insecticide disulfoton was recovered in much higher amounts (22.27 ~ 25.64% higher than control) when it was irradiated in the presence of QAUVAs in comparison with the amount of recovery of pesticide exposed in absence of them.

Reversible assembly and disassembly of gold nanorods induced by EDTA and its application in SERS tuning.

A facile and reversible method for assembling and disassembling gold nanorods (GNRs) using a common chelating agent, ethylenediaminetetraacetic acid (EDTA), is reported. Assembly was induced by the electrostatic interaction between the cetyltrimethylammonium bromide (CTAB) bilayer present on GNRs and EDTA. At lower concentrations of EDTA, end-to-end assembled chains were formed. At higher concentrations of EDTA, these chains come together to form sheet-like structures. The complex of CTAB and EDTA, being labile, disassembles in the presence of stronger chelating agents. Upon addition of metal ions having higher formation constants, EDTA detaches from the GNRs and forms stronger complexes with metal ions, resulting in disassembly. Characteristic changes were observed in the UV/vis spectra. Addition of EDTA resulted in a red shift of longitudinal surface plasmon (LSP) resonance at lower concentrations, indicating an end-to-end assembly. At higher concentrations, the characteristic of side-by-side assembly was seen in the UV/vis spectra. TEM analysis proved the existence of end-to-end chains at lower concentrations of EDTA and side-by-side assembled sheet-like structures at higher concentrations. The addition of metal ions induced disassembly. Even 2 ppb of metal ion was detected using the spectral changes. Disassembly was studied in detail, taking Pb(II) as the model system. Upon addition of Pb(II), TSP showed a blue shift and decreased in intensity while the LSP showed a red shift and increased in intensity. A new peak at a higher wavelength region emerged, pointing to the existence of both side-by-side and end-to-end assembly in the system. TEM analysis showed that the disassembly involves the formation of bundled chains which may be the reason for the observed spectral changes. Surface-enhanced Raman scattering (SERS) activity of the system could be tuned by controlling the concentration of EDTA and the metal ion, Pb(II).

Investigation into the reactivity of unsupported and supported Ag7 and Ag8 clusters with toxic metal ions.

We report the chemical interactions of unsupported and alumina-supported Ag(7) and Ag(8) clusters protected with MSA (mercaptosuccinic acid) with heavy metal ions Hg(II), Cd(II), and Pb(II) in water at different concentrations. The investigation was carried out to determine the feasibility of this interesting new class of materials called quantum clusters for water purification. These systems were studied using various spectroscopic and microscopic techniques such as ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, dynamic light scattering, zeta potential measurements, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and photoluminescence spectroscopy and in detail by X-ray photoelectron spectroscopy. We observed that the metal ions interact with both the silver atoms of the clusters and the functional groups of the capping agent (MSA). The mercuric ions were reduced to metallic mercury by both supported and unsupported clusters, due to the feasibility of the redox reaction, whereas no reduction was observed for Cd(II) and Pb(II). As a result of the interaction, the luminescence of the cluster is lost which can be used to sense Hg(II). At lower concentrations, the metal ions were chemically bonded to the carboxylate groups of MSA. Absence of reduction of Hg(II) at lower concentration is due to the chemical affinity of the ligands and the lower silver content per cluster compared to the number of carboxylate groups.

Direct analysis of camptothecin from Nothapodytes nimmoniana by desorption electrospray ionization mass spectrometry (DESI-MS).

Desorption electrospray ionization was employed for fast and direct ambient detection of the anti-tumor drug, camptothecin, and its derivative, 9-methoxycamptothecin in Nothapodytes nimmoniana. Different parts of the plant such as leaves, stems and bark were examined. The ion intensities suggest that the concentration in bark is higher than that in the leaves and stems. The method does not require any sample preparation or preseparation. The identity of the alkaloids was further confirmed by tandem mass spectrometry.